1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
13 input --> split ---------------------> overlay --> output
16 +-----> crop --> vflip -------+
19 This filtergraph splits the input stream in two streams, then sends one
20 stream through the crop filter and the vflip filter, before merging it
21 back with the other stream by overlaying it on top. You can use the
22 following command to achieve this:
25 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
28 The result will be that the top half of the video is mirrored
29 onto the bottom half of the output video.
31 Filters in the same linear chain are separated by commas, and distinct
32 linear chains of filters are separated by semicolons. In our example,
33 @var{crop,vflip} are in one linear chain, @var{split} and
34 @var{overlay} are separately in another. The points where the linear
35 chains join are labelled by names enclosed in square brackets. In the
36 example, the split filter generates two outputs that are associated to
37 the labels @var{[main]} and @var{[tmp]}.
39 The stream sent to the second output of @var{split}, labelled as
40 @var{[tmp]}, is processed through the @var{crop} filter, which crops
41 away the lower half part of the video, and then vertically flipped. The
42 @var{overlay} filter takes in input the first unchanged output of the
43 split filter (which was labelled as @var{[main]}), and overlay on its
44 lower half the output generated by the @var{crop,vflip} filterchain.
46 Some filters take in input a list of parameters: they are specified
47 after the filter name and an equal sign, and are separated from each other
50 There exist so-called @var{source filters} that do not have an
51 audio/video input, and @var{sink filters} that will not have audio/video
54 @c man end FILTERING INTRODUCTION
57 @c man begin GRAPH2DOT
59 The @file{graph2dot} program included in the FFmpeg @file{tools}
60 directory can be used to parse a filtergraph description and issue a
61 corresponding textual representation in the dot language.
68 to see how to use @file{graph2dot}.
70 You can then pass the dot description to the @file{dot} program (from
71 the graphviz suite of programs) and obtain a graphical representation
74 For example the sequence of commands:
76 echo @var{GRAPH_DESCRIPTION} | \
77 tools/graph2dot -o graph.tmp && \
78 dot -Tpng graph.tmp -o graph.png && \
82 can be used to create and display an image representing the graph
83 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
84 a complete self-contained graph, with its inputs and outputs explicitly defined.
85 For example if your command line is of the form:
87 ffmpeg -i infile -vf scale=640:360 outfile
89 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
91 nullsrc,scale=640:360,nullsink
93 you may also need to set the @var{nullsrc} parameters and add a @var{format}
94 filter in order to simulate a specific input file.
98 @chapter Filtergraph description
99 @c man begin FILTERGRAPH DESCRIPTION
101 A filtergraph is a directed graph of connected filters. It can contain
102 cycles, and there can be multiple links between a pair of
103 filters. Each link has one input pad on one side connecting it to one
104 filter from which it takes its input, and one output pad on the other
105 side connecting it to one filter accepting its output.
107 Each filter in a filtergraph is an instance of a filter class
108 registered in the application, which defines the features and the
109 number of input and output pads of the filter.
111 A filter with no input pads is called a "source", and a filter with no
112 output pads is called a "sink".
114 @anchor{Filtergraph syntax}
115 @section Filtergraph syntax
117 A filtergraph has a textual representation, which is recognized by the
118 @option{-filter}/@option{-vf}/@option{-af} and
119 @option{-filter_complex} options in @command{ffmpeg} and
120 @option{-vf}/@option{-af} in @command{ffplay}, and by the
121 @code{avfilter_graph_parse_ptr()} function defined in
122 @file{libavfilter/avfilter.h}.
124 A filterchain consists of a sequence of connected filters, each one
125 connected to the previous one in the sequence. A filterchain is
126 represented by a list of ","-separated filter descriptions.
128 A filtergraph consists of a sequence of filterchains. A sequence of
129 filterchains is represented by a list of ";"-separated filterchain
132 A filter is represented by a string of the form:
133 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
135 @var{filter_name} is the name of the filter class of which the
136 described filter is an instance of, and has to be the name of one of
137 the filter classes registered in the program.
138 The name of the filter class is optionally followed by a string
141 @var{arguments} is a string which contains the parameters used to
142 initialize the filter instance. It may have one of two forms:
146 A ':'-separated list of @var{key=value} pairs.
149 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
150 the option names in the order they are declared. E.g. the @code{fade} filter
151 declares three options in this order -- @option{type}, @option{start_frame} and
152 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
153 @var{in} is assigned to the option @option{type}, @var{0} to
154 @option{start_frame} and @var{30} to @option{nb_frames}.
157 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
158 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
159 follow the same constraints order of the previous point. The following
160 @var{key=value} pairs can be set in any preferred order.
164 If the option value itself is a list of items (e.g. the @code{format} filter
165 takes a list of pixel formats), the items in the list are usually separated by
168 The list of arguments can be quoted using the character @samp{'} as initial
169 and ending mark, and the character @samp{\} for escaping the characters
170 within the quoted text; otherwise the argument string is considered
171 terminated when the next special character (belonging to the set
172 @samp{[]=;,}) is encountered.
174 The name and arguments of the filter are optionally preceded and
175 followed by a list of link labels.
176 A link label allows one to name a link and associate it to a filter output
177 or input pad. The preceding labels @var{in_link_1}
178 ... @var{in_link_N}, are associated to the filter input pads,
179 the following labels @var{out_link_1} ... @var{out_link_M}, are
180 associated to the output pads.
182 When two link labels with the same name are found in the
183 filtergraph, a link between the corresponding input and output pad is
186 If an output pad is not labelled, it is linked by default to the first
187 unlabelled input pad of the next filter in the filterchain.
188 For example in the filterchain
190 nullsrc, split[L1], [L2]overlay, nullsink
192 the split filter instance has two output pads, and the overlay filter
193 instance two input pads. The first output pad of split is labelled
194 "L1", the first input pad of overlay is labelled "L2", and the second
195 output pad of split is linked to the second input pad of overlay,
196 which are both unlabelled.
198 In a filter description, if the input label of the first filter is not
199 specified, "in" is assumed; if the output label of the last filter is not
200 specified, "out" is assumed.
202 In a complete filterchain all the unlabelled filter input and output
203 pads must be connected. A filtergraph is considered valid if all the
204 filter input and output pads of all the filterchains are connected.
206 Libavfilter will automatically insert @ref{scale} filters where format
207 conversion is required. It is possible to specify swscale flags
208 for those automatically inserted scalers by prepending
209 @code{sws_flags=@var{flags};}
210 to the filtergraph description.
212 Here is a BNF description of the filtergraph syntax:
214 @var{NAME} ::= sequence of alphanumeric characters and '_'
215 @var{LINKLABEL} ::= "[" @var{NAME} "]"
216 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
217 @var{FILTER_ARGUMENTS} ::= sequence of chars (possibly quoted)
218 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
219 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
220 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
223 @section Notes on filtergraph escaping
225 Filtergraph description composition entails several levels of
226 escaping. See @ref{quoting_and_escaping,,the "Quoting and escaping"
227 section in the ffmpeg-utils(1) manual,ffmpeg-utils} for more
228 information about the employed escaping procedure.
230 A first level escaping affects the content of each filter option
231 value, which may contain the special character @code{:} used to
232 separate values, or one of the escaping characters @code{\'}.
234 A second level escaping affects the whole filter description, which
235 may contain the escaping characters @code{\'} or the special
236 characters @code{[],;} used by the filtergraph description.
238 Finally, when you specify a filtergraph on a shell commandline, you
239 need to perform a third level escaping for the shell special
240 characters contained within it.
242 For example, consider the following string to be embedded in
243 the @ref{drawtext} filter description @option{text} value:
245 this is a 'string': may contain one, or more, special characters
248 This string contains the @code{'} special escaping character, and the
249 @code{:} special character, so it needs to be escaped in this way:
251 text=this is a \'string\'\: may contain one, or more, special characters
254 A second level of escaping is required when embedding the filter
255 description in a filtergraph description, in order to escape all the
256 filtergraph special characters. Thus the example above becomes:
258 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
260 (note that in addition to the @code{\'} escaping special characters,
261 also @code{,} needs to be escaped).
263 Finally an additional level of escaping is needed when writing the
264 filtergraph description in a shell command, which depends on the
265 escaping rules of the adopted shell. For example, assuming that
266 @code{\} is special and needs to be escaped with another @code{\}, the
267 previous string will finally result in:
269 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
272 @chapter Timeline editing
274 Some filters support a generic @option{enable} option. For the filters
275 supporting timeline editing, this option can be set to an expression which is
276 evaluated before sending a frame to the filter. If the evaluation is non-zero,
277 the filter will be enabled, otherwise the frame will be sent unchanged to the
278 next filter in the filtergraph.
280 The expression accepts the following values:
283 timestamp expressed in seconds, NAN if the input timestamp is unknown
286 sequential number of the input frame, starting from 0
289 the position in the file of the input frame, NAN if unknown
293 width and height of the input frame if video
296 Additionally, these filters support an @option{enable} command that can be used
297 to re-define the expression.
299 Like any other filtering option, the @option{enable} option follows the same
302 For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3
303 minutes, and a @ref{curves} filter starting at 3 seconds:
305 smartblur = enable='between(t,10,3*60)',
306 curves = enable='gte(t,3)' : preset=cross_process
309 @c man end FILTERGRAPH DESCRIPTION
311 @chapter Audio Filters
312 @c man begin AUDIO FILTERS
314 When you configure your FFmpeg build, you can disable any of the
315 existing filters using @code{--disable-filters}.
316 The configure output will show the audio filters included in your
319 Below is a description of the currently available audio filters.
323 A compressor is mainly used to reduce the dynamic range of a signal.
324 Especially modern music is mostly compressed at a high ratio to
325 improve the overall loudness. It's done to get the highest attention
326 of a listener, "fatten" the sound and bring more "power" to the track.
327 If a signal is compressed too much it may sound dull or "dead"
328 afterwards or it may start to "pump" (which could be a powerful effect
329 but can also destroy a track completely).
330 The right compression is the key to reach a professional sound and is
331 the high art of mixing and mastering. Because of its complex settings
332 it may take a long time to get the right feeling for this kind of effect.
334 Compression is done by detecting the volume above a chosen level
335 @code{threshold} and dividing it by the factor set with @code{ratio}.
336 So if you set the threshold to -12dB and your signal reaches -6dB a ratio
337 of 2:1 will result in a signal at -9dB. Because an exact manipulation of
338 the signal would cause distortion of the waveform the reduction can be
339 levelled over the time. This is done by setting "Attack" and "Release".
340 @code{attack} determines how long the signal has to rise above the threshold
341 before any reduction will occur and @code{release} sets the time the signal
342 has to fall below the threshold to reduce the reduction again. Shorter signals
343 than the chosen attack time will be left untouched.
344 The overall reduction of the signal can be made up afterwards with the
345 @code{makeup} setting. So compressing the peaks of a signal about 6dB and
346 raising the makeup to this level results in a signal twice as loud than the
347 source. To gain a softer entry in the compression the @code{knee} flattens the
348 hard edge at the threshold in the range of the chosen decibels.
350 The filter accepts the following options:
354 Set input gain. Default is 1. Range is between 0.015625 and 64.
357 If a signal of second stream rises above this level it will affect the gain
358 reduction of the first stream.
359 By default it is 0.125. Range is between 0.00097563 and 1.
362 Set a ratio by which the signal is reduced. 1:2 means that if the level
363 rose 4dB above the threshold, it will be only 2dB above after the reduction.
364 Default is 2. Range is between 1 and 20.
367 Amount of milliseconds the signal has to rise above the threshold before gain
368 reduction starts. Default is 20. Range is between 0.01 and 2000.
371 Amount of milliseconds the signal has to fall below the threshold before
372 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
375 Set the amount by how much signal will be amplified after processing.
376 Default is 2. Range is from 1 and 64.
379 Curve the sharp knee around the threshold to enter gain reduction more softly.
380 Default is 2.82843. Range is between 1 and 8.
383 Choose if the @code{average} level between all channels of input stream
384 or the louder(@code{maximum}) channel of input stream affects the
385 reduction. Default is @code{average}.
388 Should the exact signal be taken in case of @code{peak} or an RMS one in case
389 of @code{rms}. Default is @code{rms} which is mostly smoother.
392 How much to use compressed signal in output. Default is 1.
393 Range is between 0 and 1.
398 Apply cross fade from one input audio stream to another input audio stream.
399 The cross fade is applied for specified duration near the end of first stream.
401 The filter accepts the following options:
405 Specify the number of samples for which the cross fade effect has to last.
406 At the end of the cross fade effect the first input audio will be completely
407 silent. Default is 44100.
410 Specify the duration of the cross fade effect. See
411 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
412 for the accepted syntax.
413 By default the duration is determined by @var{nb_samples}.
414 If set this option is used instead of @var{nb_samples}.
417 Should first stream end overlap with second stream start. Default is enabled.
420 Set curve for cross fade transition for first stream.
423 Set curve for cross fade transition for second stream.
425 For description of available curve types see @ref{afade} filter description.
432 Cross fade from one input to another:
434 ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac
438 Cross fade from one input to another but without overlapping:
440 ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac
446 Delay one or more audio channels.
448 Samples in delayed channel are filled with silence.
450 The filter accepts the following option:
454 Set list of delays in milliseconds for each channel separated by '|'.
455 At least one delay greater than 0 should be provided.
456 Unused delays will be silently ignored. If number of given delays is
457 smaller than number of channels all remaining channels will not be delayed.
464 Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
465 the second channel (and any other channels that may be present) unchanged.
473 Apply echoing to the input audio.
475 Echoes are reflected sound and can occur naturally amongst mountains
476 (and sometimes large buildings) when talking or shouting; digital echo
477 effects emulate this behaviour and are often used to help fill out the
478 sound of a single instrument or vocal. The time difference between the
479 original signal and the reflection is the @code{delay}, and the
480 loudness of the reflected signal is the @code{decay}.
481 Multiple echoes can have different delays and decays.
483 A description of the accepted parameters follows.
487 Set input gain of reflected signal. Default is @code{0.6}.
490 Set output gain of reflected signal. Default is @code{0.3}.
493 Set list of time intervals in milliseconds between original signal and reflections
494 separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}.
495 Default is @code{1000}.
498 Set list of loudnesses of reflected signals separated by '|'.
499 Allowed range for each @code{decay} is @code{(0 - 1.0]}.
500 Default is @code{0.5}.
507 Make it sound as if there are twice as many instruments as are actually playing:
509 aecho=0.8:0.88:60:0.4
513 If delay is very short, then it sound like a (metallic) robot playing music:
519 A longer delay will sound like an open air concert in the mountains:
521 aecho=0.8:0.9:1000:0.3
525 Same as above but with one more mountain:
527 aecho=0.8:0.9:1000|1800:0.3|0.25
532 Audio emphasis filter creates or restores material directly taken from LPs or
533 emphased CDs with different filter curves. E.g. to store music on vinyl the
534 signal has to be altered by a filter first to even out the disadvantages of
535 this recording medium.
536 Once the material is played back the inverse filter has to be applied to
537 restore the distortion of the frequency response.
539 The filter accepts the following options:
549 Set filter mode. For restoring material use @code{reproduction} mode, otherwise
550 use @code{production} mode. Default is @code{reproduction} mode.
553 Set filter type. Selects medium. Can be one of the following:
565 select Compact Disc (CD).
571 select 50µs (FM-KF).
573 select 75µs (FM-KF).
579 Modify an audio signal according to the specified expressions.
581 This filter accepts one or more expressions (one for each channel),
582 which are evaluated and used to modify a corresponding audio signal.
584 It accepts the following parameters:
588 Set the '|'-separated expressions list for each separate channel. If
589 the number of input channels is greater than the number of
590 expressions, the last specified expression is used for the remaining
593 @item channel_layout, c
594 Set output channel layout. If not specified, the channel layout is
595 specified by the number of expressions. If set to @samp{same}, it will
596 use by default the same input channel layout.
599 Each expression in @var{exprs} can contain the following constants and functions:
603 channel number of the current expression
606 number of the evaluated sample, starting from 0
612 time of the evaluated sample expressed in seconds
615 @item nb_out_channels
616 input and output number of channels
619 the value of input channel with number @var{CH}
622 Note: this filter is slow. For faster processing you should use a
631 aeval=val(ch)/2:c=same
635 Invert phase of the second channel:
644 Apply fade-in/out effect to input audio.
646 A description of the accepted parameters follows.
650 Specify the effect type, can be either @code{in} for fade-in, or
651 @code{out} for a fade-out effect. Default is @code{in}.
653 @item start_sample, ss
654 Specify the number of the start sample for starting to apply the fade
655 effect. Default is 0.
658 Specify the number of samples for which the fade effect has to last. At
659 the end of the fade-in effect the output audio will have the same
660 volume as the input audio, at the end of the fade-out transition
661 the output audio will be silence. Default is 44100.
664 Specify the start time of the fade effect. Default is 0.
665 The value must be specified as a time duration; see
666 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
667 for the accepted syntax.
668 If set this option is used instead of @var{start_sample}.
671 Specify the duration of the fade effect. See
672 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
673 for the accepted syntax.
674 At the end of the fade-in effect the output audio will have the same
675 volume as the input audio, at the end of the fade-out transition
676 the output audio will be silence.
677 By default the duration is determined by @var{nb_samples}.
678 If set this option is used instead of @var{nb_samples}.
681 Set curve for fade transition.
683 It accepts the following values:
686 select triangular, linear slope (default)
688 select quarter of sine wave
690 select half of sine wave
692 select exponential sine wave
696 select inverted parabola
710 select inverted quarter of sine wave
712 select inverted half of sine wave
714 select double-exponential seat
716 select double-exponential sigmoid
724 Fade in first 15 seconds of audio:
730 Fade out last 25 seconds of a 900 seconds audio:
732 afade=t=out:st=875:d=25
737 Apply arbitrary expressions to samples in frequency domain.
741 Set frequency domain real expression for each separate channel separated
742 by '|'. Default is "1".
743 If the number of input channels is greater than the number of
744 expressions, the last specified expression is used for the remaining
748 Set frequency domain imaginary expression for each separate channel
749 separated by '|'. If not set, @var{real} option is used.
751 Each expression in @var{real} and @var{imag} can contain the following
759 current frequency bin number
762 number of available bins
765 channel number of the current expression
777 It accepts the following values:
793 Default is @code{w4096}
796 Set window function. Default is @code{hann}.
799 Set window overlap. If set to 1, the recommended overlap for selected
800 window function will be picked. Default is @code{0.75}.
807 Leave almost only low frequencies in audio:
809 afftfilt="1-clip((b/nb)*b,0,1)"
816 Set output format constraints for the input audio. The framework will
817 negotiate the most appropriate format to minimize conversions.
819 It accepts the following parameters:
823 A '|'-separated list of requested sample formats.
826 A '|'-separated list of requested sample rates.
828 @item channel_layouts
829 A '|'-separated list of requested channel layouts.
831 See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils}
832 for the required syntax.
835 If a parameter is omitted, all values are allowed.
837 Force the output to either unsigned 8-bit or signed 16-bit stereo
839 aformat=sample_fmts=u8|s16:channel_layouts=stereo
844 A gate is mainly used to reduce lower parts of a signal. This kind of signal
845 processing reduces disturbing noise between useful signals.
847 Gating is done by detecting the volume below a chosen level @var{threshold}
848 and divide it by the factor set with @var{ratio}. The bottom of the noise
849 floor is set via @var{range}. Because an exact manipulation of the signal
850 would cause distortion of the waveform the reduction can be levelled over
851 time. This is done by setting @var{attack} and @var{release}.
853 @var{attack} determines how long the signal has to fall below the threshold
854 before any reduction will occur and @var{release} sets the time the signal
855 has to raise above the threshold to reduce the reduction again.
856 Shorter signals than the chosen attack time will be left untouched.
860 Set input level before filtering.
861 Default is 1. Allowed range is from 0.015625 to 64.
864 Set the level of gain reduction when the signal is below the threshold.
865 Default is 0.06125. Allowed range is from 0 to 1.
868 If a signal rises above this level the gain reduction is released.
869 Default is 0.125. Allowed range is from 0 to 1.
872 Set a ratio about which the signal is reduced.
873 Default is 2. Allowed range is from 1 to 9000.
876 Amount of milliseconds the signal has to rise above the threshold before gain
878 Default is 20 milliseconds. Allowed range is from 0.01 to 9000.
881 Amount of milliseconds the signal has to fall below the threshold before the
882 reduction is increased again. Default is 250 milliseconds.
883 Allowed range is from 0.01 to 9000.
886 Set amount of amplification of signal after processing.
887 Default is 1. Allowed range is from 1 to 64.
890 Curve the sharp knee around the threshold to enter gain reduction more softly.
891 Default is 2.828427125. Allowed range is from 1 to 8.
894 Choose if exact signal should be taken for detection or an RMS like one.
895 Default is rms. Can be peak or rms.
898 Choose if the average level between all channels or the louder channel affects
900 Default is average. Can be average or maximum.
905 The limiter prevents input signal from raising over a desired threshold.
906 This limiter uses lookahead technology to prevent your signal from distorting.
907 It means that there is a small delay after signal is processed. Keep in mind
908 that the delay it produces is the attack time you set.
910 The filter accepts the following options:
914 Set input gain. Default is 1.
917 Set output gain. Default is 1.
920 Don't let signals above this level pass the limiter. Default is 1.
923 The limiter will reach its attenuation level in this amount of time in
924 milliseconds. Default is 5 milliseconds.
927 Come back from limiting to attenuation 1.0 in this amount of milliseconds.
928 Default is 50 milliseconds.
931 When gain reduction is always needed ASC takes care of releasing to an
932 average reduction level rather than reaching a reduction of 0 in the release
936 Select how much the release time is affected by ASC, 0 means nearly no changes
937 in release time while 1 produces higher release times.
940 Auto level output signal. Default is enabled.
941 This normalizes audio back to 0dB if enabled.
944 Depending on picked setting it is recommended to upsample input 2x or 4x times
945 with @ref{aresample} before applying this filter.
949 Apply a two-pole all-pass filter with central frequency (in Hz)
950 @var{frequency}, and filter-width @var{width}.
951 An all-pass filter changes the audio's frequency to phase relationship
952 without changing its frequency to amplitude relationship.
954 The filter accepts the following options:
961 Set method to specify band-width of filter.
974 Specify the band-width of a filter in width_type units.
980 Merge two or more audio streams into a single multi-channel stream.
982 The filter accepts the following options:
987 Set the number of inputs. Default is 2.
991 If the channel layouts of the inputs are disjoint, and therefore compatible,
992 the channel layout of the output will be set accordingly and the channels
993 will be reordered as necessary. If the channel layouts of the inputs are not
994 disjoint, the output will have all the channels of the first input then all
995 the channels of the second input, in that order, and the channel layout of
996 the output will be the default value corresponding to the total number of
999 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
1000 is FC+BL+BR, then the output will be in 5.1, with the channels in the
1001 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
1002 first input, b1 is the first channel of the second input).
1004 On the other hand, if both input are in stereo, the output channels will be
1005 in the default order: a1, a2, b1, b2, and the channel layout will be
1006 arbitrarily set to 4.0, which may or may not be the expected value.
1008 All inputs must have the same sample rate, and format.
1010 If inputs do not have the same duration, the output will stop with the
1013 @subsection Examples
1017 Merge two mono files into a stereo stream:
1019 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
1023 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
1025 ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
1031 Mixes multiple audio inputs into a single output.
1033 Note that this filter only supports float samples (the @var{amerge}
1034 and @var{pan} audio filters support many formats). If the @var{amix}
1035 input has integer samples then @ref{aresample} will be automatically
1036 inserted to perform the conversion to float samples.
1040 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
1042 will mix 3 input audio streams to a single output with the same duration as the
1043 first input and a dropout transition time of 3 seconds.
1045 It accepts the following parameters:
1049 The number of inputs. If unspecified, it defaults to 2.
1052 How to determine the end-of-stream.
1056 The duration of the longest input. (default)
1059 The duration of the shortest input.
1062 The duration of the first input.
1066 @item dropout_transition
1067 The transition time, in seconds, for volume renormalization when an input
1068 stream ends. The default value is 2 seconds.
1072 @section anequalizer
1074 High-order parametric multiband equalizer for each channel.
1076 It accepts the following parameters:
1080 This option string is in format:
1081 "c@var{chn} f=@var{cf} w=@var{w} g=@var{g} t=@var{f} | ..."
1082 Each equalizer band is separated by '|'.
1086 Set channel number to which equalization will be applied.
1087 If input doesn't have that channel the entry is ignored.
1090 Set central frequency for band.
1091 If input doesn't have that frequency the entry is ignored.
1094 Set band width in hertz.
1097 Set band gain in dB.
1100 Set filter type for band, optional, can be:
1104 Butterworth, this is default.
1115 With this option activated frequency response of anequalizer is displayed
1119 Set video stream size. Only useful if curves option is activated.
1122 Set max gain that will be displayed. Only useful if curves option is activated.
1123 Setting this to reasonable value allows to display gain which is derived from
1124 neighbour bands which are too close to each other and thus produce higher gain
1125 when both are activated.
1128 Set frequency scale used to draw frequency response in video output.
1129 Can be linear or logarithmic. Default is logarithmic.
1132 Set color for each channel curve which is going to be displayed in video stream.
1133 This is list of color names separated by space or by '|'.
1134 Unrecognised or missing colors will be replaced by white color.
1137 @subsection Examples
1141 Lower gain by 10 of central frequency 200Hz and width 100 Hz
1142 for first 2 channels using Chebyshev type 1 filter:
1144 anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1
1148 @subsection Commands
1150 This filter supports the following commands:
1153 Alter existing filter parameters.
1154 Syntax for the commands is : "@var{fN}|f=@var{freq}|w=@var{width}|g=@var{gain}"
1156 @var{fN} is existing filter number, starting from 0, if no such filter is available
1158 @var{freq} set new frequency parameter.
1159 @var{width} set new width parameter in herz.
1160 @var{gain} set new gain parameter in dB.
1162 Full filter invocation with asendcmd may look like this:
1163 asendcmd=c='4.0 anequalizer change 0|f=200|w=50|g=1',anequalizer=...
1168 Pass the audio source unchanged to the output.
1172 Pad the end of an audio stream with silence.
1174 This can be used together with @command{ffmpeg} @option{-shortest} to
1175 extend audio streams to the same length as the video stream.
1177 A description of the accepted options follows.
1181 Set silence packet size. Default value is 4096.
1184 Set the number of samples of silence to add to the end. After the
1185 value is reached, the stream is terminated. This option is mutually
1186 exclusive with @option{whole_len}.
1189 Set the minimum total number of samples in the output audio stream. If
1190 the value is longer than the input audio length, silence is added to
1191 the end, until the value is reached. This option is mutually exclusive
1192 with @option{pad_len}.
1195 If neither the @option{pad_len} nor the @option{whole_len} option is
1196 set, the filter will add silence to the end of the input stream
1199 @subsection Examples
1203 Add 1024 samples of silence to the end of the input:
1209 Make sure the audio output will contain at least 10000 samples, pad
1210 the input with silence if required:
1212 apad=whole_len=10000
1216 Use @command{ffmpeg} to pad the audio input with silence, so that the
1217 video stream will always result the shortest and will be converted
1218 until the end in the output file when using the @option{shortest}
1221 ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT
1226 Add a phasing effect to the input audio.
1228 A phaser filter creates series of peaks and troughs in the frequency spectrum.
1229 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
1231 A description of the accepted parameters follows.
1235 Set input gain. Default is 0.4.
1238 Set output gain. Default is 0.74
1241 Set delay in milliseconds. Default is 3.0.
1244 Set decay. Default is 0.4.
1247 Set modulation speed in Hz. Default is 0.5.
1250 Set modulation type. Default is triangular.
1252 It accepts the following values:
1261 Audio pulsator is something between an autopanner and a tremolo.
1262 But it can produce funny stereo effects as well. Pulsator changes the volume
1263 of the left and right channel based on a LFO (low frequency oscillator) with
1264 different waveforms and shifted phases.
1265 This filter have the ability to define an offset between left and right
1266 channel. An offset of 0 means that both LFO shapes match each other.
1267 The left and right channel are altered equally - a conventional tremolo.
1268 An offset of 50% means that the shape of the right channel is exactly shifted
1269 in phase (or moved backwards about half of the frequency) - pulsator acts as
1270 an autopanner. At 1 both curves match again. Every setting in between moves the
1271 phase shift gapless between all stages and produces some "bypassing" sounds with
1272 sine and triangle waveforms. The more you set the offset near 1 (starting from
1273 the 0.5) the faster the signal passes from the left to the right speaker.
1275 The filter accepts the following options:
1279 Set input gain. By default it is 1. Range is [0.015625 - 64].
1282 Set output gain. By default it is 1. Range is [0.015625 - 64].
1285 Set waveform shape the LFO will use. Can be one of: sine, triangle, square,
1286 sawup or sawdown. Default is sine.
1289 Set modulation. Define how much of original signal is affected by the LFO.
1292 Set left channel offset. Default is 0. Allowed range is [0 - 1].
1295 Set right channel offset. Default is 0.5. Allowed range is [0 - 1].
1298 Set pulse width. Default is 1. Allowed range is [0 - 2].
1301 Set possible timing mode. Can be one of: bpm, ms or hz. Default is hz.
1304 Set bpm. Default is 120. Allowed range is [30 - 300]. Only used if timing
1308 Set ms. Default is 500. Allowed range is [10 - 2000]. Only used if timing
1312 Set frequency in Hz. Default is 2. Allowed range is [0.01 - 100]. Only used
1313 if timing is set to hz.
1319 Resample the input audio to the specified parameters, using the
1320 libswresample library. If none are specified then the filter will
1321 automatically convert between its input and output.
1323 This filter is also able to stretch/squeeze the audio data to make it match
1324 the timestamps or to inject silence / cut out audio to make it match the
1325 timestamps, do a combination of both or do neither.
1327 The filter accepts the syntax
1328 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
1329 expresses a sample rate and @var{resampler_options} is a list of
1330 @var{key}=@var{value} pairs, separated by ":". See the
1331 ffmpeg-resampler manual for the complete list of supported options.
1333 @subsection Examples
1337 Resample the input audio to 44100Hz:
1343 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
1344 samples per second compensation:
1346 aresample=async=1000
1350 @section asetnsamples
1352 Set the number of samples per each output audio frame.
1354 The last output packet may contain a different number of samples, as
1355 the filter will flush all the remaining samples when the input audio
1358 The filter accepts the following options:
1362 @item nb_out_samples, n
1363 Set the number of frames per each output audio frame. The number is
1364 intended as the number of samples @emph{per each channel}.
1365 Default value is 1024.
1368 If set to 1, the filter will pad the last audio frame with zeroes, so
1369 that the last frame will contain the same number of samples as the
1370 previous ones. Default value is 1.
1373 For example, to set the number of per-frame samples to 1234 and
1374 disable padding for the last frame, use:
1376 asetnsamples=n=1234:p=0
1381 Set the sample rate without altering the PCM data.
1382 This will result in a change of speed and pitch.
1384 The filter accepts the following options:
1387 @item sample_rate, r
1388 Set the output sample rate. Default is 44100 Hz.
1393 Show a line containing various information for each input audio frame.
1394 The input audio is not modified.
1396 The shown line contains a sequence of key/value pairs of the form
1397 @var{key}:@var{value}.
1399 The following values are shown in the output:
1403 The (sequential) number of the input frame, starting from 0.
1406 The presentation timestamp of the input frame, in time base units; the time base
1407 depends on the filter input pad, and is usually 1/@var{sample_rate}.
1410 The presentation timestamp of the input frame in seconds.
1413 position of the frame in the input stream, -1 if this information in
1414 unavailable and/or meaningless (for example in case of synthetic audio)
1423 The sample rate for the audio frame.
1426 The number of samples (per channel) in the frame.
1429 The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
1430 audio, the data is treated as if all the planes were concatenated.
1432 @item plane_checksums
1433 A list of Adler-32 checksums for each data plane.
1439 Display time domain statistical information about the audio channels.
1440 Statistics are calculated and displayed for each audio channel and,
1441 where applicable, an overall figure is also given.
1443 It accepts the following option:
1446 Short window length in seconds, used for peak and trough RMS measurement.
1447 Default is @code{0.05} (50 milliseconds). Allowed range is @code{[0.1 - 10]}.
1451 Set metadata injection. All the metadata keys are prefixed with @code{lavfi.astats.X},
1452 where @code{X} is channel number starting from 1 or string @code{Overall}. Default is
1455 Available keys for each channel are:
1486 For example full key look like this @code{lavfi.astats.1.DC_offset} or
1487 this @code{lavfi.astats.Overall.Peak_count}.
1489 For description what each key means read below.
1492 Set number of frame after which stats are going to be recalculated.
1493 Default is disabled.
1496 A description of each shown parameter follows:
1500 Mean amplitude displacement from zero.
1503 Minimal sample level.
1506 Maximal sample level.
1508 @item Min difference
1509 Minimal difference between two consecutive samples.
1511 @item Max difference
1512 Maximal difference between two consecutive samples.
1514 @item Mean difference
1515 Mean difference between two consecutive samples.
1516 The average of each difference between two consecutive samples.
1520 Standard peak and RMS level measured in dBFS.
1524 Peak and trough values for RMS level measured over a short window.
1527 Standard ratio of peak to RMS level (note: not in dB).
1530 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
1531 (i.e. either @var{Min level} or @var{Max level}).
1534 Number of occasions (not the number of samples) that the signal attained either
1535 @var{Min level} or @var{Max level}.
1538 Overall bit depth of audio. Number of bits used for each sample.
1543 Synchronize audio data with timestamps by squeezing/stretching it and/or
1544 dropping samples/adding silence when needed.
1546 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1548 It accepts the following parameters:
1552 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1553 by default. When disabled, time gaps are covered with silence.
1556 The minimum difference between timestamps and audio data (in seconds) to trigger
1557 adding/dropping samples. The default value is 0.1. If you get an imperfect
1558 sync with this filter, try setting this parameter to 0.
1561 The maximum compensation in samples per second. Only relevant with compensate=1.
1562 The default value is 500.
1565 Assume that the first PTS should be this value. The time base is 1 / sample
1566 rate. This allows for padding/trimming at the start of the stream. By default,
1567 no assumption is made about the first frame's expected PTS, so no padding or
1568 trimming is done. For example, this could be set to 0 to pad the beginning with
1569 silence if an audio stream starts after the video stream or to trim any samples
1570 with a negative PTS due to encoder delay.
1578 The filter accepts exactly one parameter, the audio tempo. If not
1579 specified then the filter will assume nominal 1.0 tempo. Tempo must
1580 be in the [0.5, 2.0] range.
1582 @subsection Examples
1586 Slow down audio to 80% tempo:
1592 To speed up audio to 125% tempo:
1600 Trim the input so that the output contains one continuous subpart of the input.
1602 It accepts the following parameters:
1605 Timestamp (in seconds) of the start of the section to keep. I.e. the audio
1606 sample with the timestamp @var{start} will be the first sample in the output.
1609 Specify time of the first audio sample that will be dropped, i.e. the
1610 audio sample immediately preceding the one with the timestamp @var{end} will be
1611 the last sample in the output.
1614 Same as @var{start}, except this option sets the start timestamp in samples
1618 Same as @var{end}, except this option sets the end timestamp in samples instead
1622 The maximum duration of the output in seconds.
1625 The number of the first sample that should be output.
1628 The number of the first sample that should be dropped.
1631 @option{start}, @option{end}, and @option{duration} are expressed as time
1632 duration specifications; see
1633 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
1635 Note that the first two sets of the start/end options and the @option{duration}
1636 option look at the frame timestamp, while the _sample options simply count the
1637 samples that pass through the filter. So start/end_pts and start/end_sample will
1638 give different results when the timestamps are wrong, inexact or do not start at
1639 zero. Also note that this filter does not modify the timestamps. If you wish
1640 to have the output timestamps start at zero, insert the asetpts filter after the
1643 If multiple start or end options are set, this filter tries to be greedy and
1644 keep all samples that match at least one of the specified constraints. To keep
1645 only the part that matches all the constraints at once, chain multiple atrim
1648 The defaults are such that all the input is kept. So it is possible to set e.g.
1649 just the end values to keep everything before the specified time.
1654 Drop everything except the second minute of input:
1656 ffmpeg -i INPUT -af atrim=60:120
1660 Keep only the first 1000 samples:
1662 ffmpeg -i INPUT -af atrim=end_sample=1000
1669 Apply a two-pole Butterworth band-pass filter with central
1670 frequency @var{frequency}, and (3dB-point) band-width width.
1671 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1672 instead of the default: constant 0dB peak gain.
1673 The filter roll off at 6dB per octave (20dB per decade).
1675 The filter accepts the following options:
1679 Set the filter's central frequency. Default is @code{3000}.
1682 Constant skirt gain if set to 1. Defaults to 0.
1685 Set method to specify band-width of filter.
1698 Specify the band-width of a filter in width_type units.
1703 Apply a two-pole Butterworth band-reject filter with central
1704 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1705 The filter roll off at 6dB per octave (20dB per decade).
1707 The filter accepts the following options:
1711 Set the filter's central frequency. Default is @code{3000}.
1714 Set method to specify band-width of filter.
1727 Specify the band-width of a filter in width_type units.
1732 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1733 shelving filter with a response similar to that of a standard
1734 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1736 The filter accepts the following options:
1740 Give the gain at 0 Hz. Its useful range is about -20
1741 (for a large cut) to +20 (for a large boost).
1742 Beware of clipping when using a positive gain.
1745 Set the filter's central frequency and so can be used
1746 to extend or reduce the frequency range to be boosted or cut.
1747 The default value is @code{100} Hz.
1750 Set method to specify band-width of filter.
1763 Determine how steep is the filter's shelf transition.
1768 Apply a biquad IIR filter with the given coefficients.
1769 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1770 are the numerator and denominator coefficients respectively.
1773 Bauer stereo to binaural transformation, which improves headphone listening of
1774 stereo audio records.
1776 It accepts the following parameters:
1780 Pre-defined crossfeed level.
1784 Default level (fcut=700, feed=50).
1787 Chu Moy circuit (fcut=700, feed=60).
1790 Jan Meier circuit (fcut=650, feed=95).
1795 Cut frequency (in Hz).
1804 Remap input channels to new locations.
1806 It accepts the following parameters:
1808 @item channel_layout
1809 The channel layout of the output stream.
1812 Map channels from input to output. The argument is a '|'-separated list of
1813 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1814 @var{in_channel} form. @var{in_channel} can be either the name of the input
1815 channel (e.g. FL for front left) or its index in the input channel layout.
1816 @var{out_channel} is the name of the output channel or its index in the output
1817 channel layout. If @var{out_channel} is not given then it is implicitly an
1818 index, starting with zero and increasing by one for each mapping.
1821 If no mapping is present, the filter will implicitly map input channels to
1822 output channels, preserving indices.
1824 For example, assuming a 5.1+downmix input MOV file,
1826 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1828 will create an output WAV file tagged as stereo from the downmix channels of
1831 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1833 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
1836 @section channelsplit
1838 Split each channel from an input audio stream into a separate output stream.
1840 It accepts the following parameters:
1842 @item channel_layout
1843 The channel layout of the input stream. The default is "stereo".
1846 For example, assuming a stereo input MP3 file,
1848 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1850 will create an output Matroska file with two audio streams, one containing only
1851 the left channel and the other the right channel.
1853 Split a 5.1 WAV file into per-channel files:
1855 ffmpeg -i in.wav -filter_complex
1856 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1857 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1858 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1863 Add a chorus effect to the audio.
1865 Can make a single vocal sound like a chorus, but can also be applied to instrumentation.
1867 Chorus resembles an echo effect with a short delay, but whereas with echo the delay is
1868 constant, with chorus, it is varied using using sinusoidal or triangular modulation.
1869 The modulation depth defines the range the modulated delay is played before or after
1870 the delay. Hence the delayed sound will sound slower or faster, that is the delayed
1871 sound tuned around the original one, like in a chorus where some vocals are slightly
1874 It accepts the following parameters:
1877 Set input gain. Default is 0.4.
1880 Set output gain. Default is 0.4.
1883 Set delays. A typical delay is around 40ms to 60ms.
1895 @subsection Examples
1901 chorus=0.7:0.9:55:0.4:0.25:2
1907 chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3
1911 Fuller sounding chorus with three delays:
1913 chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3
1918 Compress or expand the audio's dynamic range.
1920 It accepts the following parameters:
1926 A list of times in seconds for each channel over which the instantaneous level
1927 of the input signal is averaged to determine its volume. @var{attacks} refers to
1928 increase of volume and @var{decays} refers to decrease of volume. For most
1929 situations, the attack time (response to the audio getting louder) should be
1930 shorter than the decay time, because the human ear is more sensitive to sudden
1931 loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
1932 a typical value for decay is 0.8 seconds.
1933 If specified number of attacks & decays is lower than number of channels, the last
1934 set attack/decay will be used for all remaining channels.
1937 A list of points for the transfer function, specified in dB relative to the
1938 maximum possible signal amplitude. Each key points list must be defined using
1939 the following syntax: @code{x0/y0|x1/y1|x2/y2|....} or
1940 @code{x0/y0 x1/y1 x2/y2 ....}
1942 The input values must be in strictly increasing order but the transfer function
1943 does not have to be monotonically rising. The point @code{0/0} is assumed but
1944 may be overridden (by @code{0/out-dBn}). Typical values for the transfer
1945 function are @code{-70/-70|-60/-20}.
1948 Set the curve radius in dB for all joints. It defaults to 0.01.
1951 Set the additional gain in dB to be applied at all points on the transfer
1952 function. This allows for easy adjustment of the overall gain.
1956 Set an initial volume, in dB, to be assumed for each channel when filtering
1957 starts. This permits the user to supply a nominal level initially, so that, for
1958 example, a very large gain is not applied to initial signal levels before the
1959 companding has begun to operate. A typical value for audio which is initially
1960 quiet is -90 dB. It defaults to 0.
1963 Set a delay, in seconds. The input audio is analyzed immediately, but audio is
1964 delayed before being fed to the volume adjuster. Specifying a delay
1965 approximately equal to the attack/decay times allows the filter to effectively
1966 operate in predictive rather than reactive mode. It defaults to 0.
1970 @subsection Examples
1974 Make music with both quiet and loud passages suitable for listening to in a
1977 compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
1980 Another example for audio with whisper and explosion parts:
1982 compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0
1986 A noise gate for when the noise is at a lower level than the signal:
1988 compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
1992 Here is another noise gate, this time for when the noise is at a higher level
1993 than the signal (making it, in some ways, similar to squelch):
1995 compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
1999 2:1 compression starting at -6dB:
2001 compand=points=-80/-80|-6/-6|0/-3.8|20/3.5
2005 2:1 compression starting at -9dB:
2007 compand=points=-80/-80|-9/-9|0/-5.3|20/2.9
2011 2:1 compression starting at -12dB:
2013 compand=points=-80/-80|-12/-12|0/-6.8|20/1.9
2017 2:1 compression starting at -18dB:
2019 compand=points=-80/-80|-18/-18|0/-9.8|20/0.7
2023 3:1 compression starting at -15dB:
2025 compand=points=-80/-80|-15/-15|0/-10.8|20/-5.2
2031 compand=points=-80/-105|-62/-80|-15.4/-15.4|0/-12|20/-7.6
2037 compand=attacks=0:points=-80/-169|-54/-80|-49.5/-64.6|-41.1/-41.1|-25.8/-15|-10.8/-4.5|0/0|20/8.3
2041 Hard limiter at -6dB:
2043 compand=attacks=0:points=-80/-80|-6/-6|20/-6
2047 Hard limiter at -12dB:
2049 compand=attacks=0:points=-80/-80|-12/-12|20/-12
2053 Hard noise gate at -35 dB:
2055 compand=attacks=0:points=-80/-115|-35.1/-80|-35/-35|20/20
2061 compand=attacks=0:points=-80/-80|-12.4/-12.4|-6/-8|0/-6.8|20/-2.8
2065 @section compensationdelay
2067 Compensation Delay Line is a metric based delay to compensate differing
2068 positions of microphones or speakers.
2070 For example, you have recorded guitar with two microphones placed in
2071 different location. Because the front of sound wave has fixed speed in
2072 normal conditions, the phasing of microphones can vary and depends on
2073 their location and interposition. The best sound mix can be achieved when
2074 these microphones are in phase (synchronized). Note that distance of
2075 ~30 cm between microphones makes one microphone to capture signal in
2076 antiphase to another microphone. That makes the final mix sounding moody.
2077 This filter helps to solve phasing problems by adding different delays
2078 to each microphone track and make them synchronized.
2080 The best result can be reached when you take one track as base and
2081 synchronize other tracks one by one with it.
2082 Remember that synchronization/delay tolerance depends on sample rate, too.
2083 Higher sample rates will give more tolerance.
2085 It accepts the following parameters:
2089 Set millimeters distance. This is compensation distance for fine tuning.
2093 Set cm distance. This is compensation distance for tightening distance setup.
2097 Set meters distance. This is compensation distance for hard distance setup.
2101 Set dry amount. Amount of unprocessed (dry) signal.
2105 Set wet amount. Amount of processed (wet) signal.
2109 Set temperature degree in Celsius. This is the temperature of the environment.
2114 Apply a DC shift to the audio.
2116 This can be useful to remove a DC offset (caused perhaps by a hardware problem
2117 in the recording chain) from the audio. The effect of a DC offset is reduced
2118 headroom and hence volume. The @ref{astats} filter can be used to determine if
2119 a signal has a DC offset.
2123 Set the DC shift, allowed range is [-1, 1]. It indicates the amount to shift
2127 Optional. It should have a value much less than 1 (e.g. 0.05 or 0.02) and is
2128 used to prevent clipping.
2132 Dynamic Audio Normalizer.
2134 This filter applies a certain amount of gain to the input audio in order
2135 to bring its peak magnitude to a target level (e.g. 0 dBFS). However, in
2136 contrast to more "simple" normalization algorithms, the Dynamic Audio
2137 Normalizer *dynamically* re-adjusts the gain factor to the input audio.
2138 This allows for applying extra gain to the "quiet" sections of the audio
2139 while avoiding distortions or clipping the "loud" sections. In other words:
2140 The Dynamic Audio Normalizer will "even out" the volume of quiet and loud
2141 sections, in the sense that the volume of each section is brought to the
2142 same target level. Note, however, that the Dynamic Audio Normalizer achieves
2143 this goal *without* applying "dynamic range compressing". It will retain 100%
2144 of the dynamic range *within* each section of the audio file.
2148 Set the frame length in milliseconds. In range from 10 to 8000 milliseconds.
2149 Default is 500 milliseconds.
2150 The Dynamic Audio Normalizer processes the input audio in small chunks,
2151 referred to as frames. This is required, because a peak magnitude has no
2152 meaning for just a single sample value. Instead, we need to determine the
2153 peak magnitude for a contiguous sequence of sample values. While a "standard"
2154 normalizer would simply use the peak magnitude of the complete file, the
2155 Dynamic Audio Normalizer determines the peak magnitude individually for each
2156 frame. The length of a frame is specified in milliseconds. By default, the
2157 Dynamic Audio Normalizer uses a frame length of 500 milliseconds, which has
2158 been found to give good results with most files.
2159 Note that the exact frame length, in number of samples, will be determined
2160 automatically, based on the sampling rate of the individual input audio file.
2163 Set the Gaussian filter window size. In range from 3 to 301, must be odd
2164 number. Default is 31.
2165 Probably the most important parameter of the Dynamic Audio Normalizer is the
2166 @code{window size} of the Gaussian smoothing filter. The filter's window size
2167 is specified in frames, centered around the current frame. For the sake of
2168 simplicity, this must be an odd number. Consequently, the default value of 31
2169 takes into account the current frame, as well as the 15 preceding frames and
2170 the 15 subsequent frames. Using a larger window results in a stronger
2171 smoothing effect and thus in less gain variation, i.e. slower gain
2172 adaptation. Conversely, using a smaller window results in a weaker smoothing
2173 effect and thus in more gain variation, i.e. faster gain adaptation.
2174 In other words, the more you increase this value, the more the Dynamic Audio
2175 Normalizer will behave like a "traditional" normalization filter. On the
2176 contrary, the more you decrease this value, the more the Dynamic Audio
2177 Normalizer will behave like a dynamic range compressor.
2180 Set the target peak value. This specifies the highest permissible magnitude
2181 level for the normalized audio input. This filter will try to approach the
2182 target peak magnitude as closely as possible, but at the same time it also
2183 makes sure that the normalized signal will never exceed the peak magnitude.
2184 A frame's maximum local gain factor is imposed directly by the target peak
2185 magnitude. The default value is 0.95 and thus leaves a headroom of 5%*.
2186 It is not recommended to go above this value.
2189 Set the maximum gain factor. In range from 1.0 to 100.0. Default is 10.0.
2190 The Dynamic Audio Normalizer determines the maximum possible (local) gain
2191 factor for each input frame, i.e. the maximum gain factor that does not
2192 result in clipping or distortion. The maximum gain factor is determined by
2193 the frame's highest magnitude sample. However, the Dynamic Audio Normalizer
2194 additionally bounds the frame's maximum gain factor by a predetermined
2195 (global) maximum gain factor. This is done in order to avoid excessive gain
2196 factors in "silent" or almost silent frames. By default, the maximum gain
2197 factor is 10.0, For most inputs the default value should be sufficient and
2198 it usually is not recommended to increase this value. Though, for input
2199 with an extremely low overall volume level, it may be necessary to allow even
2200 higher gain factors. Note, however, that the Dynamic Audio Normalizer does
2201 not simply apply a "hard" threshold (i.e. cut off values above the threshold).
2202 Instead, a "sigmoid" threshold function will be applied. This way, the
2203 gain factors will smoothly approach the threshold value, but never exceed that
2207 Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 - disabled.
2208 By default, the Dynamic Audio Normalizer performs "peak" normalization.
2209 This means that the maximum local gain factor for each frame is defined
2210 (only) by the frame's highest magnitude sample. This way, the samples can
2211 be amplified as much as possible without exceeding the maximum signal
2212 level, i.e. without clipping. Optionally, however, the Dynamic Audio
2213 Normalizer can also take into account the frame's root mean square,
2214 abbreviated RMS. In electrical engineering, the RMS is commonly used to
2215 determine the power of a time-varying signal. It is therefore considered
2216 that the RMS is a better approximation of the "perceived loudness" than
2217 just looking at the signal's peak magnitude. Consequently, by adjusting all
2218 frames to a constant RMS value, a uniform "perceived loudness" can be
2219 established. If a target RMS value has been specified, a frame's local gain
2220 factor is defined as the factor that would result in exactly that RMS value.
2221 Note, however, that the maximum local gain factor is still restricted by the
2222 frame's highest magnitude sample, in order to prevent clipping.
2225 Enable channels coupling. By default is enabled.
2226 By default, the Dynamic Audio Normalizer will amplify all channels by the same
2227 amount. This means the same gain factor will be applied to all channels, i.e.
2228 the maximum possible gain factor is determined by the "loudest" channel.
2229 However, in some recordings, it may happen that the volume of the different
2230 channels is uneven, e.g. one channel may be "quieter" than the other one(s).
2231 In this case, this option can be used to disable the channel coupling. This way,
2232 the gain factor will be determined independently for each channel, depending
2233 only on the individual channel's highest magnitude sample. This allows for
2234 harmonizing the volume of the different channels.
2237 Enable DC bias correction. By default is disabled.
2238 An audio signal (in the time domain) is a sequence of sample values.
2239 In the Dynamic Audio Normalizer these sample values are represented in the
2240 -1.0 to 1.0 range, regardless of the original input format. Normally, the
2241 audio signal, or "waveform", should be centered around the zero point.
2242 That means if we calculate the mean value of all samples in a file, or in a
2243 single frame, then the result should be 0.0 or at least very close to that
2244 value. If, however, there is a significant deviation of the mean value from
2245 0.0, in either positive or negative direction, this is referred to as a
2246 DC bias or DC offset. Since a DC bias is clearly undesirable, the Dynamic
2247 Audio Normalizer provides optional DC bias correction.
2248 With DC bias correction enabled, the Dynamic Audio Normalizer will determine
2249 the mean value, or "DC correction" offset, of each input frame and subtract
2250 that value from all of the frame's sample values which ensures those samples
2251 are centered around 0.0 again. Also, in order to avoid "gaps" at the frame
2252 boundaries, the DC correction offset values will be interpolated smoothly
2253 between neighbouring frames.
2256 Enable alternative boundary mode. By default is disabled.
2257 The Dynamic Audio Normalizer takes into account a certain neighbourhood
2258 around each frame. This includes the preceding frames as well as the
2259 subsequent frames. However, for the "boundary" frames, located at the very
2260 beginning and at the very end of the audio file, not all neighbouring
2261 frames are available. In particular, for the first few frames in the audio
2262 file, the preceding frames are not known. And, similarly, for the last few
2263 frames in the audio file, the subsequent frames are not known. Thus, the
2264 question arises which gain factors should be assumed for the missing frames
2265 in the "boundary" region. The Dynamic Audio Normalizer implements two modes
2266 to deal with this situation. The default boundary mode assumes a gain factor
2267 of exactly 1.0 for the missing frames, resulting in a smooth "fade in" and
2268 "fade out" at the beginning and at the end of the input, respectively.
2271 Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
2272 By default, the Dynamic Audio Normalizer does not apply "traditional"
2273 compression. This means that signal peaks will not be pruned and thus the
2274 full dynamic range will be retained within each local neighbourhood. However,
2275 in some cases it may be desirable to combine the Dynamic Audio Normalizer's
2276 normalization algorithm with a more "traditional" compression.
2277 For this purpose, the Dynamic Audio Normalizer provides an optional compression
2278 (thresholding) function. If (and only if) the compression feature is enabled,
2279 all input frames will be processed by a soft knee thresholding function prior
2280 to the actual normalization process. Put simply, the thresholding function is
2281 going to prune all samples whose magnitude exceeds a certain threshold value.
2282 However, the Dynamic Audio Normalizer does not simply apply a fixed threshold
2283 value. Instead, the threshold value will be adjusted for each individual
2285 In general, smaller parameters result in stronger compression, and vice versa.
2286 Values below 3.0 are not recommended, because audible distortion may appear.
2291 Make audio easier to listen to on headphones.
2293 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
2294 so that when listened to on headphones the stereo image is moved from
2295 inside your head (standard for headphones) to outside and in front of
2296 the listener (standard for speakers).
2302 Apply a two-pole peaking equalisation (EQ) filter. With this
2303 filter, the signal-level at and around a selected frequency can
2304 be increased or decreased, whilst (unlike bandpass and bandreject
2305 filters) that at all other frequencies is unchanged.
2307 In order to produce complex equalisation curves, this filter can
2308 be given several times, each with a different central frequency.
2310 The filter accepts the following options:
2314 Set the filter's central frequency in Hz.
2317 Set method to specify band-width of filter.
2330 Specify the band-width of a filter in width_type units.
2333 Set the required gain or attenuation in dB.
2334 Beware of clipping when using a positive gain.
2337 @subsection Examples
2340 Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
2342 equalizer=f=1000:width_type=h:width=200:g=-10
2346 Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
2348 equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
2352 @section extrastereo
2354 Linearly increases the difference between left and right channels which
2355 adds some sort of "live" effect to playback.
2357 The filter accepts the following option:
2361 Sets the difference coefficient (default: 2.5). 0.0 means mono sound
2362 (average of both channels), with 1.0 sound will be unchanged, with
2363 -1.0 left and right channels will be swapped.
2366 Enable clipping. By default is enabled.
2369 @section firequalizer
2370 Apply FIR Equalization using arbitrary frequency response.
2372 The filter accepts the following option:
2376 Set gain curve equation (in dB). The expression can contain variables:
2379 the evaluated frequency
2383 channel number, set to 0 when multichannels evaluation is disabled
2385 channel id, see libavutil/channel_layout.h, set to the first channel id when
2386 multichannels evaluation is disabled
2390 channel_layout, see libavutil/channel_layout.h
2395 @item gain_interpolate(f)
2396 interpolate gain on frequency f based on gain_entry
2398 This option is also available as command. Default is @code{gain_interpolate(f)}.
2401 Set gain entry for gain_interpolate function. The expression can
2405 store gain entry at frequency f with value g
2407 This option is also available as command.
2410 Set filter delay in seconds. Higher value means more accurate.
2411 Default is @code{0.01}.
2414 Set filter accuracy in Hz. Lower value means more accurate.
2415 Default is @code{5}.
2418 Set window function. Acceptable values are:
2421 rectangular window, useful when gain curve is already smooth
2423 hann window (default)
2429 3-terms continuous 1st derivative nuttall window
2431 minimum 3-terms discontinuous nuttall window
2433 4-terms continuous 1st derivative nuttall window
2435 minimum 4-terms discontinuous nuttall (blackman-nuttall) window
2437 blackman-harris window
2441 If enabled, use fixed number of audio samples. This improves speed when
2442 filtering with large delay. Default is disabled.
2445 Enable multichannels evaluation on gain. Default is disabled.
2448 @subsection Examples
2453 firequalizer=gain='if(lt(f,1000), 0, -INF)'
2456 lowpass at 1000 Hz with gain_entry:
2458 firequalizer=gain_entry='entry(1000,0); entry(1001, -INF)'
2461 custom equalization:
2463 firequalizer=gain_entry='entry(100,0); entry(400, -4); entry(1000, -6); entry(2000, 0)'
2468 firequalizer=delay=0.1:fixed=on
2471 lowpass on left channel, highpass on right channel:
2473 firequalizer=gain='if(eq(chid,1), gain_interpolate(f), if(eq(chid,2), gain_interpolate(1e6+f), 0))'
2474 :gain_entry='entry(1000, 0); entry(1001,-INF); entry(1e6+1000,0)':multi=on
2479 Apply a flanging effect to the audio.
2481 The filter accepts the following options:
2485 Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
2488 Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2.
2491 Set percentage regeneration (delayed signal feedback). Range from -95 to 95.
2495 Set percentage of delayed signal mixed with original. Range from 0 to 100.
2496 Default value is 71.
2499 Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
2502 Set swept wave shape, can be @var{triangular} or @var{sinusoidal}.
2503 Default value is @var{sinusoidal}.
2506 Set swept wave percentage-shift for multi channel. Range from 0 to 100.
2507 Default value is 25.
2510 Set delay-line interpolation, @var{linear} or @var{quadratic}.
2511 Default is @var{linear}.
2516 Apply a high-pass filter with 3dB point frequency.
2517 The filter can be either single-pole, or double-pole (the default).
2518 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2520 The filter accepts the following options:
2524 Set frequency in Hz. Default is 3000.
2527 Set number of poles. Default is 2.
2530 Set method to specify band-width of filter.
2543 Specify the band-width of a filter in width_type units.
2544 Applies only to double-pole filter.
2545 The default is 0.707q and gives a Butterworth response.
2550 Join multiple input streams into one multi-channel stream.
2552 It accepts the following parameters:
2556 The number of input streams. It defaults to 2.
2558 @item channel_layout
2559 The desired output channel layout. It defaults to stereo.
2562 Map channels from inputs to output. The argument is a '|'-separated list of
2563 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
2564 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
2565 can be either the name of the input channel (e.g. FL for front left) or its
2566 index in the specified input stream. @var{out_channel} is the name of the output
2570 The filter will attempt to guess the mappings when they are not specified
2571 explicitly. It does so by first trying to find an unused matching input channel
2572 and if that fails it picks the first unused input channel.
2574 Join 3 inputs (with properly set channel layouts):
2576 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
2579 Build a 5.1 output from 6 single-channel streams:
2581 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
2582 'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
2588 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
2590 To enable compilation of this filter you need to configure FFmpeg with
2591 @code{--enable-ladspa}.
2595 Specifies the name of LADSPA plugin library to load. If the environment
2596 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
2597 each one of the directories specified by the colon separated list in
2598 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
2599 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
2600 @file{/usr/lib/ladspa/}.
2603 Specifies the plugin within the library. Some libraries contain only
2604 one plugin, but others contain many of them. If this is not set filter
2605 will list all available plugins within the specified library.
2608 Set the '|' separated list of controls which are zero or more floating point
2609 values that determine the behavior of the loaded plugin (for example delay,
2611 Controls need to be defined using the following syntax:
2612 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
2613 @var{valuei} is the value set on the @var{i}-th control.
2614 Alternatively they can be also defined using the following syntax:
2615 @var{value0}|@var{value1}|@var{value2}|..., where
2616 @var{valuei} is the value set on the @var{i}-th control.
2617 If @option{controls} is set to @code{help}, all available controls and
2618 their valid ranges are printed.
2620 @item sample_rate, s
2621 Specify the sample rate, default to 44100. Only used if plugin have
2625 Set the number of samples per channel per each output frame, default
2626 is 1024. Only used if plugin have zero inputs.
2629 Set the minimum duration of the sourced audio. See
2630 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2631 for the accepted syntax.
2632 Note that the resulting duration may be greater than the specified duration,
2633 as the generated audio is always cut at the end of a complete frame.
2634 If not specified, or the expressed duration is negative, the audio is
2635 supposed to be generated forever.
2636 Only used if plugin have zero inputs.
2640 @subsection Examples
2644 List all available plugins within amp (LADSPA example plugin) library:
2650 List all available controls and their valid ranges for @code{vcf_notch}
2651 plugin from @code{VCF} library:
2653 ladspa=f=vcf:p=vcf_notch:c=help
2657 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
2660 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
2664 Add reverberation to the audio using TAP-plugins
2665 (Tom's Audio Processing plugins):
2667 ladspa=file=tap_reverb:tap_reverb
2671 Generate white noise, with 0.2 amplitude:
2673 ladspa=file=cmt:noise_source_white:c=c0=.2
2677 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
2678 @code{C* Audio Plugin Suite} (CAPS) library:
2680 ladspa=file=caps:Click:c=c1=20'
2684 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
2686 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
2690 Increase volume by 20dB using fast lookahead limiter from Steve Harris
2691 @code{SWH Plugins} collection:
2693 ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2
2697 Attenuate low frequencies using Multiband EQ from Steve Harris
2698 @code{SWH Plugins} collection:
2700 ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0
2704 @subsection Commands
2706 This filter supports the following commands:
2709 Modify the @var{N}-th control value.
2711 If the specified value is not valid, it is ignored and prior one is kept.
2716 Apply a low-pass filter with 3dB point frequency.
2717 The filter can be either single-pole or double-pole (the default).
2718 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2720 The filter accepts the following options:
2724 Set frequency in Hz. Default is 500.
2727 Set number of poles. Default is 2.
2730 Set method to specify band-width of filter.
2743 Specify the band-width of a filter in width_type units.
2744 Applies only to double-pole filter.
2745 The default is 0.707q and gives a Butterworth response.
2751 Mix channels with specific gain levels. The filter accepts the output
2752 channel layout followed by a set of channels definitions.
2754 This filter is also designed to efficiently remap the channels of an audio
2757 The filter accepts parameters of the form:
2758 "@var{l}|@var{outdef}|@var{outdef}|..."
2762 output channel layout or number of channels
2765 output channel specification, of the form:
2766 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
2769 output channel to define, either a channel name (FL, FR, etc.) or a channel
2770 number (c0, c1, etc.)
2773 multiplicative coefficient for the channel, 1 leaving the volume unchanged
2776 input channel to use, see out_name for details; it is not possible to mix
2777 named and numbered input channels
2780 If the `=' in a channel specification is replaced by `<', then the gains for
2781 that specification will be renormalized so that the total is 1, thus
2782 avoiding clipping noise.
2784 @subsection Mixing examples
2786 For example, if you want to down-mix from stereo to mono, but with a bigger
2787 factor for the left channel:
2789 pan=1c|c0=0.9*c0+0.1*c1
2792 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
2793 7-channels surround:
2795 pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
2798 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
2799 that should be preferred (see "-ac" option) unless you have very specific
2802 @subsection Remapping examples
2804 The channel remapping will be effective if, and only if:
2807 @item gain coefficients are zeroes or ones,
2808 @item only one input per channel output,
2811 If all these conditions are satisfied, the filter will notify the user ("Pure
2812 channel mapping detected"), and use an optimized and lossless method to do the
2815 For example, if you have a 5.1 source and want a stereo audio stream by
2816 dropping the extra channels:
2818 pan="stereo| c0=FL | c1=FR"
2821 Given the same source, you can also switch front left and front right channels
2822 and keep the input channel layout:
2824 pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
2827 If the input is a stereo audio stream, you can mute the front left channel (and
2828 still keep the stereo channel layout) with:
2833 Still with a stereo audio stream input, you can copy the right channel in both
2834 front left and right:
2836 pan="stereo| c0=FR | c1=FR"
2841 ReplayGain scanner filter. This filter takes an audio stream as an input and
2842 outputs it unchanged.
2843 At end of filtering it displays @code{track_gain} and @code{track_peak}.
2847 Convert the audio sample format, sample rate and channel layout. It is
2848 not meant to be used directly.
2851 Apply time-stretching and pitch-shifting with librubberband.
2853 The filter accepts the following options:
2857 Set tempo scale factor.
2860 Set pitch scale factor.
2863 Set transients detector.
2864 Possible values are:
2873 Possible values are:
2882 Possible values are:
2889 Set processing window size.
2890 Possible values are:
2899 Possible values are:
2906 Enable formant preservation when shift pitching.
2907 Possible values are:
2915 Possible values are:
2924 Possible values are:
2931 @section sidechaincompress
2933 This filter acts like normal compressor but has the ability to compress
2934 detected signal using second input signal.
2935 It needs two input streams and returns one output stream.
2936 First input stream will be processed depending on second stream signal.
2937 The filtered signal then can be filtered with other filters in later stages of
2938 processing. See @ref{pan} and @ref{amerge} filter.
2940 The filter accepts the following options:
2944 Set input gain. Default is 1. Range is between 0.015625 and 64.
2947 If a signal of second stream raises above this level it will affect the gain
2948 reduction of first stream.
2949 By default is 0.125. Range is between 0.00097563 and 1.
2952 Set a ratio about which the signal is reduced. 1:2 means that if the level
2953 raised 4dB above the threshold, it will be only 2dB above after the reduction.
2954 Default is 2. Range is between 1 and 20.
2957 Amount of milliseconds the signal has to rise above the threshold before gain
2958 reduction starts. Default is 20. Range is between 0.01 and 2000.
2961 Amount of milliseconds the signal has to fall below the threshold before
2962 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
2965 Set the amount by how much signal will be amplified after processing.
2966 Default is 2. Range is from 1 and 64.
2969 Curve the sharp knee around the threshold to enter gain reduction more softly.
2970 Default is 2.82843. Range is between 1 and 8.
2973 Choose if the @code{average} level between all channels of side-chain stream
2974 or the louder(@code{maximum}) channel of side-chain stream affects the
2975 reduction. Default is @code{average}.
2978 Should the exact signal be taken in case of @code{peak} or an RMS one in case
2979 of @code{rms}. Default is @code{rms} which is mainly smoother.
2982 Set sidechain gain. Default is 1. Range is between 0.015625 and 64.
2985 How much to use compressed signal in output. Default is 1.
2986 Range is between 0 and 1.
2989 @subsection Examples
2993 Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
2994 depending on the signal of 2nd input and later compressed signal to be
2995 merged with 2nd input:
2997 ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
3001 @section sidechaingate
3003 A sidechain gate acts like a normal (wideband) gate but has the ability to
3004 filter the detected signal before sending it to the gain reduction stage.
3005 Normally a gate uses the full range signal to detect a level above the
3007 For example: If you cut all lower frequencies from your sidechain signal
3008 the gate will decrease the volume of your track only if not enough highs
3009 appear. With this technique you are able to reduce the resonation of a
3010 natural drum or remove "rumbling" of muted strokes from a heavily distorted
3012 It needs two input streams and returns one output stream.
3013 First input stream will be processed depending on second stream signal.
3015 The filter accepts the following options:
3019 Set input level before filtering.
3020 Default is 1. Allowed range is from 0.015625 to 64.
3023 Set the level of gain reduction when the signal is below the threshold.
3024 Default is 0.06125. Allowed range is from 0 to 1.
3027 If a signal rises above this level the gain reduction is released.
3028 Default is 0.125. Allowed range is from 0 to 1.
3031 Set a ratio about which the signal is reduced.
3032 Default is 2. Allowed range is from 1 to 9000.
3035 Amount of milliseconds the signal has to rise above the threshold before gain
3037 Default is 20 milliseconds. Allowed range is from 0.01 to 9000.
3040 Amount of milliseconds the signal has to fall below the threshold before the
3041 reduction is increased again. Default is 250 milliseconds.
3042 Allowed range is from 0.01 to 9000.
3045 Set amount of amplification of signal after processing.
3046 Default is 1. Allowed range is from 1 to 64.
3049 Curve the sharp knee around the threshold to enter gain reduction more softly.
3050 Default is 2.828427125. Allowed range is from 1 to 8.
3053 Choose if exact signal should be taken for detection or an RMS like one.
3054 Default is rms. Can be peak or rms.
3057 Choose if the average level between all channels or the louder channel affects
3059 Default is average. Can be average or maximum.
3062 Set sidechain gain. Default is 1. Range is from 0.015625 to 64.
3065 @section silencedetect
3067 Detect silence in an audio stream.
3069 This filter logs a message when it detects that the input audio volume is less
3070 or equal to a noise tolerance value for a duration greater or equal to the
3071 minimum detected noise duration.
3073 The printed times and duration are expressed in seconds.
3075 The filter accepts the following options:
3079 Set silence duration until notification (default is 2 seconds).
3082 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
3083 specified value) or amplitude ratio. Default is -60dB, or 0.001.
3086 @subsection Examples
3090 Detect 5 seconds of silence with -50dB noise tolerance:
3092 silencedetect=n=-50dB:d=5
3096 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
3097 tolerance in @file{silence.mp3}:
3099 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
3103 @section silenceremove
3105 Remove silence from the beginning, middle or end of the audio.
3107 The filter accepts the following options:
3111 This value is used to indicate if audio should be trimmed at beginning of
3112 the audio. A value of zero indicates no silence should be trimmed from the
3113 beginning. When specifying a non-zero value, it trims audio up until it
3114 finds non-silence. Normally, when trimming silence from beginning of audio
3115 the @var{start_periods} will be @code{1} but it can be increased to higher
3116 values to trim all audio up to specific count of non-silence periods.
3117 Default value is @code{0}.
3119 @item start_duration
3120 Specify the amount of time that non-silence must be detected before it stops
3121 trimming audio. By increasing the duration, bursts of noises can be treated
3122 as silence and trimmed off. Default value is @code{0}.
3124 @item start_threshold
3125 This indicates what sample value should be treated as silence. For digital
3126 audio, a value of @code{0} may be fine but for audio recorded from analog,
3127 you may wish to increase the value to account for background noise.
3128 Can be specified in dB (in case "dB" is appended to the specified value)
3129 or amplitude ratio. Default value is @code{0}.
3132 Set the count for trimming silence from the end of audio.
3133 To remove silence from the middle of a file, specify a @var{stop_periods}
3134 that is negative. This value is then treated as a positive value and is
3135 used to indicate the effect should restart processing as specified by
3136 @var{start_periods}, making it suitable for removing periods of silence
3137 in the middle of the audio.
3138 Default value is @code{0}.
3141 Specify a duration of silence that must exist before audio is not copied any
3142 more. By specifying a higher duration, silence that is wanted can be left in
3144 Default value is @code{0}.
3146 @item stop_threshold
3147 This is the same as @option{start_threshold} but for trimming silence from
3149 Can be specified in dB (in case "dB" is appended to the specified value)
3150 or amplitude ratio. Default value is @code{0}.
3153 This indicate that @var{stop_duration} length of audio should be left intact
3154 at the beginning of each period of silence.
3155 For example, if you want to remove long pauses between words but do not want
3156 to remove the pauses completely. Default value is @code{0}.
3159 Set how is silence detected. Can be @code{rms} or @code{peak}. Second is faster
3160 and works better with digital silence which is exactly 0.
3161 Default value is @code{rms}.
3164 Set ratio used to calculate size of window for detecting silence.
3165 Default value is @code{0.02}. Allowed range is from @code{0} to @code{10}.
3168 @subsection Examples
3172 The following example shows how this filter can be used to start a recording
3173 that does not contain the delay at the start which usually occurs between
3174 pressing the record button and the start of the performance:
3176 silenceremove=1:5:0.02
3180 Trim all silence encountered from begining to end where there is more than 1
3181 second of silence in audio:
3183 silenceremove=0:0:0:-1:1:-90dB
3189 SOFAlizer uses head-related transfer functions (HRTFs) to create virtual
3190 loudspeakers around the user for binaural listening via headphones (audio
3191 formats up to 9 channels supported).
3192 The HRTFs are stored in SOFA files (see @url{http://www.sofacoustics.org/} for a database).
3193 SOFAlizer is developed at the Acoustics Research Institute (ARI) of the
3194 Austrian Academy of Sciences.
3196 To enable compilation of this filter you need to configure FFmpeg with
3197 @code{--enable-netcdf}.
3199 The filter accepts the following options:
3203 Set the SOFA file used for rendering.
3206 Set gain applied to audio. Value is in dB. Default is 0.
3209 Set rotation of virtual loudspeakers in deg. Default is 0.
3212 Set elevation of virtual speakers in deg. Default is 0.
3215 Set distance in meters between loudspeakers and the listener with near-field
3216 HRTFs. Default is 1.
3219 Set processing type. Can be @var{time} or @var{freq}. @var{time} is
3220 processing audio in time domain which is slow but gives high quality output.
3221 @var{freq} is processing audio in frequency domain which is fast but gives
3222 mediocre output. Default is @var{freq}.
3225 @section stereotools
3227 This filter has some handy utilities to manage stereo signals, for converting
3228 M/S stereo recordings to L/R signal while having control over the parameters
3229 or spreading the stereo image of master track.
3231 The filter accepts the following options:
3235 Set input level before filtering for both channels. Defaults is 1.
3236 Allowed range is from 0.015625 to 64.
3239 Set output level after filtering for both channels. Defaults is 1.
3240 Allowed range is from 0.015625 to 64.
3243 Set input balance between both channels. Default is 0.
3244 Allowed range is from -1 to 1.
3247 Set output balance between both channels. Default is 0.
3248 Allowed range is from -1 to 1.
3251 Enable softclipping. Results in analog distortion instead of harsh digital 0dB
3252 clipping. Disabled by default.
3255 Mute the left channel. Disabled by default.
3258 Mute the right channel. Disabled by default.
3261 Change the phase of the left channel. Disabled by default.
3264 Change the phase of the right channel. Disabled by default.
3267 Set stereo mode. Available values are:
3271 Left/Right to Left/Right, this is default.
3274 Left/Right to Mid/Side.
3277 Mid/Side to Left/Right.
3280 Left/Right to Left/Left.
3283 Left/Right to Right/Right.
3286 Left/Right to Left + Right.
3289 Left/Right to Right/Left.
3293 Set level of side signal. Default is 1.
3294 Allowed range is from 0.015625 to 64.
3297 Set balance of side signal. Default is 0.
3298 Allowed range is from -1 to 1.
3301 Set level of the middle signal. Default is 1.
3302 Allowed range is from 0.015625 to 64.
3305 Set middle signal pan. Default is 0. Allowed range is from -1 to 1.
3308 Set stereo base between mono and inversed channels. Default is 0.
3309 Allowed range is from -1 to 1.
3312 Set delay in milliseconds how much to delay left from right channel and
3313 vice versa. Default is 0. Allowed range is from -20 to 20.
3316 Set S/C level. Default is 1. Allowed range is from 1 to 100.
3319 Set the stereo phase in degrees. Default is 0. Allowed range is from 0 to 360.
3322 @section stereowiden
3324 This filter enhance the stereo effect by suppressing signal common to both
3325 channels and by delaying the signal of left into right and vice versa,
3326 thereby widening the stereo effect.
3328 The filter accepts the following options:
3332 Time in milliseconds of the delay of left signal into right and vice versa.
3333 Default is 20 milliseconds.
3336 Amount of gain in delayed signal into right and vice versa. Gives a delay
3337 effect of left signal in right output and vice versa which gives widening
3338 effect. Default is 0.3.
3341 Cross feed of left into right with inverted phase. This helps in suppressing
3342 the mono. If the value is 1 it will cancel all the signal common to both
3343 channels. Default is 0.3.
3346 Set level of input signal of original channel. Default is 0.8.
3351 Boost or cut treble (upper) frequencies of the audio using a two-pole
3352 shelving filter with a response similar to that of a standard
3353 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
3355 The filter accepts the following options:
3359 Give the gain at whichever is the lower of ~22 kHz and the
3360 Nyquist frequency. Its useful range is about -20 (for a large cut)
3361 to +20 (for a large boost). Beware of clipping when using a positive gain.
3364 Set the filter's central frequency and so can be used
3365 to extend or reduce the frequency range to be boosted or cut.
3366 The default value is @code{3000} Hz.
3369 Set method to specify band-width of filter.
3382 Determine how steep is the filter's shelf transition.
3387 Sinusoidal amplitude modulation.
3389 The filter accepts the following options:
3393 Modulation frequency in Hertz. Modulation frequencies in the subharmonic range
3394 (20 Hz or lower) will result in a tremolo effect.
3395 This filter may also be used as a ring modulator by specifying
3396 a modulation frequency higher than 20 Hz.
3397 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
3400 Depth of modulation as a percentage. Range is 0.0 - 1.0.
3401 Default value is 0.5.
3406 Sinusoidal phase modulation.
3408 The filter accepts the following options:
3412 Modulation frequency in Hertz.
3413 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
3416 Depth of modulation as a percentage. Range is 0.0 - 1.0.
3417 Default value is 0.5.
3422 Adjust the input audio volume.
3424 It accepts the following parameters:
3428 Set audio volume expression.
3430 Output values are clipped to the maximum value.
3432 The output audio volume is given by the relation:
3434 @var{output_volume} = @var{volume} * @var{input_volume}
3437 The default value for @var{volume} is "1.0".
3440 This parameter represents the mathematical precision.
3442 It determines which input sample formats will be allowed, which affects the
3443 precision of the volume scaling.
3447 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
3449 32-bit floating-point; this limits input sample format to FLT. (default)
3451 64-bit floating-point; this limits input sample format to DBL.
3455 Choose the behaviour on encountering ReplayGain side data in input frames.
3459 Remove ReplayGain side data, ignoring its contents (the default).
3462 Ignore ReplayGain side data, but leave it in the frame.
3465 Prefer the track gain, if present.
3468 Prefer the album gain, if present.
3471 @item replaygain_preamp
3472 Pre-amplification gain in dB to apply to the selected replaygain gain.
3474 Default value for @var{replaygain_preamp} is 0.0.
3477 Set when the volume expression is evaluated.
3479 It accepts the following values:
3482 only evaluate expression once during the filter initialization, or
3483 when the @samp{volume} command is sent
3486 evaluate expression for each incoming frame
3489 Default value is @samp{once}.
3492 The volume expression can contain the following parameters.
3496 frame number (starting at zero)
3499 @item nb_consumed_samples
3500 number of samples consumed by the filter
3502 number of samples in the current frame
3504 original frame position in the file
3510 PTS at start of stream
3512 time at start of stream
3518 last set volume value
3521 Note that when @option{eval} is set to @samp{once} only the
3522 @var{sample_rate} and @var{tb} variables are available, all other
3523 variables will evaluate to NAN.
3525 @subsection Commands
3527 This filter supports the following commands:
3530 Modify the volume expression.
3531 The command accepts the same syntax of the corresponding option.
3533 If the specified expression is not valid, it is kept at its current
3535 @item replaygain_noclip
3536 Prevent clipping by limiting the gain applied.
3538 Default value for @var{replaygain_noclip} is 1.
3542 @subsection Examples
3546 Halve the input audio volume:
3550 volume=volume=-6.0206dB
3553 In all the above example the named key for @option{volume} can be
3554 omitted, for example like in:
3560 Increase input audio power by 6 decibels using fixed-point precision:
3562 volume=volume=6dB:precision=fixed
3566 Fade volume after time 10 with an annihilation period of 5 seconds:
3568 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
3572 @section volumedetect
3574 Detect the volume of the input video.
3576 The filter has no parameters. The input is not modified. Statistics about
3577 the volume will be printed in the log when the input stream end is reached.
3579 In particular it will show the mean volume (root mean square), maximum
3580 volume (on a per-sample basis), and the beginning of a histogram of the
3581 registered volume values (from the maximum value to a cumulated 1/1000 of
3584 All volumes are in decibels relative to the maximum PCM value.
3586 @subsection Examples
3588 Here is an excerpt of the output:
3590 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
3591 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
3592 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
3593 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
3594 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
3595 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
3596 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
3597 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
3598 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
3604 The mean square energy is approximately -27 dB, or 10^-2.7.
3606 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
3608 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
3611 In other words, raising the volume by +4 dB does not cause any clipping,
3612 raising it by +5 dB causes clipping for 6 samples, etc.
3614 @c man end AUDIO FILTERS
3616 @chapter Audio Sources
3617 @c man begin AUDIO SOURCES
3619 Below is a description of the currently available audio sources.
3623 Buffer audio frames, and make them available to the filter chain.
3625 This source is mainly intended for a programmatic use, in particular
3626 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
3628 It accepts the following parameters:
3632 The timebase which will be used for timestamps of submitted frames. It must be
3633 either a floating-point number or in @var{numerator}/@var{denominator} form.
3636 The sample rate of the incoming audio buffers.
3639 The sample format of the incoming audio buffers.
3640 Either a sample format name or its corresponding integer representation from
3641 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
3643 @item channel_layout
3644 The channel layout of the incoming audio buffers.
3645 Either a channel layout name from channel_layout_map in
3646 @file{libavutil/channel_layout.c} or its corresponding integer representation
3647 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
3650 The number of channels of the incoming audio buffers.
3651 If both @var{channels} and @var{channel_layout} are specified, then they
3656 @subsection Examples
3659 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
3662 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
3663 Since the sample format with name "s16p" corresponds to the number
3664 6 and the "stereo" channel layout corresponds to the value 0x3, this is
3667 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
3672 Generate an audio signal specified by an expression.
3674 This source accepts in input one or more expressions (one for each
3675 channel), which are evaluated and used to generate a corresponding
3678 This source accepts the following options:
3682 Set the '|'-separated expressions list for each separate channel. In case the
3683 @option{channel_layout} option is not specified, the selected channel layout
3684 depends on the number of provided expressions. Otherwise the last
3685 specified expression is applied to the remaining output channels.
3687 @item channel_layout, c
3688 Set the channel layout. The number of channels in the specified layout
3689 must be equal to the number of specified expressions.
3692 Set the minimum duration of the sourced audio. See
3693 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
3694 for the accepted syntax.
3695 Note that the resulting duration may be greater than the specified
3696 duration, as the generated audio is always cut at the end of a
3699 If not specified, or the expressed duration is negative, the audio is
3700 supposed to be generated forever.
3703 Set the number of samples per channel per each output frame,
3706 @item sample_rate, s
3707 Specify the sample rate, default to 44100.
3710 Each expression in @var{exprs} can contain the following constants:
3714 number of the evaluated sample, starting from 0
3717 time of the evaluated sample expressed in seconds, starting from 0
3724 @subsection Examples
3734 Generate a sin signal with frequency of 440 Hz, set sample rate to
3737 aevalsrc="sin(440*2*PI*t):s=8000"
3741 Generate a two channels signal, specify the channel layout (Front
3742 Center + Back Center) explicitly:
3744 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
3748 Generate white noise:
3750 aevalsrc="-2+random(0)"
3754 Generate an amplitude modulated signal:
3756 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
3760 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
3762 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
3769 The null audio source, return unprocessed audio frames. It is mainly useful
3770 as a template and to be employed in analysis / debugging tools, or as
3771 the source for filters which ignore the input data (for example the sox
3774 This source accepts the following options:
3778 @item channel_layout, cl
3780 Specifies the channel layout, and can be either an integer or a string
3781 representing a channel layout. The default value of @var{channel_layout}
3784 Check the channel_layout_map definition in
3785 @file{libavutil/channel_layout.c} for the mapping between strings and
3786 channel layout values.
3788 @item sample_rate, r
3789 Specifies the sample rate, and defaults to 44100.
3792 Set the number of samples per requested frames.
3796 @subsection Examples
3800 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
3802 anullsrc=r=48000:cl=4
3806 Do the same operation with a more obvious syntax:
3808 anullsrc=r=48000:cl=mono
3812 All the parameters need to be explicitly defined.
3816 Synthesize a voice utterance using the libflite library.
3818 To enable compilation of this filter you need to configure FFmpeg with
3819 @code{--enable-libflite}.
3821 Note that the flite library is not thread-safe.
3823 The filter accepts the following options:
3828 If set to 1, list the names of the available voices and exit
3829 immediately. Default value is 0.
3832 Set the maximum number of samples per frame. Default value is 512.
3835 Set the filename containing the text to speak.
3838 Set the text to speak.
3841 Set the voice to use for the speech synthesis. Default value is
3842 @code{kal}. See also the @var{list_voices} option.
3845 @subsection Examples
3849 Read from file @file{speech.txt}, and synthesize the text using the
3850 standard flite voice:
3852 flite=textfile=speech.txt
3856 Read the specified text selecting the @code{slt} voice:
3858 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3862 Input text to ffmpeg:
3864 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3868 Make @file{ffplay} speak the specified text, using @code{flite} and
3869 the @code{lavfi} device:
3871 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
3875 For more information about libflite, check:
3876 @url{http://www.speech.cs.cmu.edu/flite/}
3880 Generate a noise audio signal.
3882 The filter accepts the following options:
3885 @item sample_rate, r
3886 Specify the sample rate. Default value is 48000 Hz.
3889 Specify the amplitude (0.0 - 1.0) of the generated audio stream. Default value
3893 Specify the duration of the generated audio stream. Not specifying this option
3894 results in noise with an infinite length.
3896 @item color, colour, c
3897 Specify the color of noise. Available noise colors are white, pink, and brown.
3898 Default color is white.
3901 Specify a value used to seed the PRNG.
3904 Set the number of samples per each output frame, default is 1024.
3907 @subsection Examples
3912 Generate 60 seconds of pink noise, with a 44.1 kHz sampling rate and an amplitude of 0.5:
3914 anoisesrc=d=60:c=pink:r=44100:a=0.5
3920 Generate an audio signal made of a sine wave with amplitude 1/8.
3922 The audio signal is bit-exact.
3924 The filter accepts the following options:
3929 Set the carrier frequency. Default is 440 Hz.
3931 @item beep_factor, b
3932 Enable a periodic beep every second with frequency @var{beep_factor} times
3933 the carrier frequency. Default is 0, meaning the beep is disabled.
3935 @item sample_rate, r
3936 Specify the sample rate, default is 44100.
3939 Specify the duration of the generated audio stream.
3941 @item samples_per_frame
3942 Set the number of samples per output frame.
3944 The expression can contain the following constants:
3948 The (sequential) number of the output audio frame, starting from 0.
3951 The PTS (Presentation TimeStamp) of the output audio frame,
3952 expressed in @var{TB} units.
3955 The PTS of the output audio frame, expressed in seconds.
3958 The timebase of the output audio frames.
3961 Default is @code{1024}.
3964 @subsection Examples
3969 Generate a simple 440 Hz sine wave:
3975 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
3979 sine=frequency=220:beep_factor=4:duration=5
3983 Generate a 1 kHz sine wave following @code{1602,1601,1602,1601,1602} NTSC
3986 sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
3990 @c man end AUDIO SOURCES
3992 @chapter Audio Sinks
3993 @c man begin AUDIO SINKS
3995 Below is a description of the currently available audio sinks.
3997 @section abuffersink
3999 Buffer audio frames, and make them available to the end of filter chain.
4001 This sink is mainly intended for programmatic use, in particular
4002 through the interface defined in @file{libavfilter/buffersink.h}
4003 or the options system.
4005 It accepts a pointer to an AVABufferSinkContext structure, which
4006 defines the incoming buffers' formats, to be passed as the opaque
4007 parameter to @code{avfilter_init_filter} for initialization.
4010 Null audio sink; do absolutely nothing with the input audio. It is
4011 mainly useful as a template and for use in analysis / debugging
4014 @c man end AUDIO SINKS
4016 @chapter Video Filters
4017 @c man begin VIDEO FILTERS
4019 When you configure your FFmpeg build, you can disable any of the
4020 existing filters using @code{--disable-filters}.
4021 The configure output will show the video filters included in your
4024 Below is a description of the currently available video filters.
4026 @section alphaextract
4028 Extract the alpha component from the input as a grayscale video. This
4029 is especially useful with the @var{alphamerge} filter.
4033 Add or replace the alpha component of the primary input with the
4034 grayscale value of a second input. This is intended for use with
4035 @var{alphaextract} to allow the transmission or storage of frame
4036 sequences that have alpha in a format that doesn't support an alpha
4039 For example, to reconstruct full frames from a normal YUV-encoded video
4040 and a separate video created with @var{alphaextract}, you might use:
4042 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
4045 Since this filter is designed for reconstruction, it operates on frame
4046 sequences without considering timestamps, and terminates when either
4047 input reaches end of stream. This will cause problems if your encoding
4048 pipeline drops frames. If you're trying to apply an image as an
4049 overlay to a video stream, consider the @var{overlay} filter instead.
4053 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
4054 and libavformat to work. On the other hand, it is limited to ASS (Advanced
4055 Substation Alpha) subtitles files.
4057 This filter accepts the following option in addition to the common options from
4058 the @ref{subtitles} filter:
4062 Set the shaping engine
4064 Available values are:
4067 The default libass shaping engine, which is the best available.
4069 Fast, font-agnostic shaper that can do only substitutions
4071 Slower shaper using OpenType for substitutions and positioning
4074 The default is @code{auto}.
4078 Apply an Adaptive Temporal Averaging Denoiser to the video input.
4080 The filter accepts the following options:
4084 Set threshold A for 1st plane. Default is 0.02.
4085 Valid range is 0 to 0.3.
4088 Set threshold B for 1st plane. Default is 0.04.
4089 Valid range is 0 to 5.
4092 Set threshold A for 2nd plane. Default is 0.02.
4093 Valid range is 0 to 0.3.
4096 Set threshold B for 2nd plane. Default is 0.04.
4097 Valid range is 0 to 5.
4100 Set threshold A for 3rd plane. Default is 0.02.
4101 Valid range is 0 to 0.3.
4104 Set threshold B for 3rd plane. Default is 0.04.
4105 Valid range is 0 to 5.
4107 Threshold A is designed to react on abrupt changes in the input signal and
4108 threshold B is designed to react on continuous changes in the input signal.
4111 Set number of frames filter will use for averaging. Default is 33. Must be odd
4112 number in range [5, 129].
4117 Compute the bounding box for the non-black pixels in the input frame
4120 This filter computes the bounding box containing all the pixels with a
4121 luminance value greater than the minimum allowed value.
4122 The parameters describing the bounding box are printed on the filter
4125 The filter accepts the following option:
4129 Set the minimal luminance value. Default is @code{16}.
4132 @section blackdetect
4134 Detect video intervals that are (almost) completely black. Can be
4135 useful to detect chapter transitions, commercials, or invalid
4136 recordings. Output lines contains the time for the start, end and
4137 duration of the detected black interval expressed in seconds.
4139 In order to display the output lines, you need to set the loglevel at
4140 least to the AV_LOG_INFO value.
4142 The filter accepts the following options:
4145 @item black_min_duration, d
4146 Set the minimum detected black duration expressed in seconds. It must
4147 be a non-negative floating point number.
4149 Default value is 2.0.
4151 @item picture_black_ratio_th, pic_th
4152 Set the threshold for considering a picture "black".
4153 Express the minimum value for the ratio:
4155 @var{nb_black_pixels} / @var{nb_pixels}
4158 for which a picture is considered black.
4159 Default value is 0.98.
4161 @item pixel_black_th, pix_th
4162 Set the threshold for considering a pixel "black".
4164 The threshold expresses the maximum pixel luminance value for which a
4165 pixel is considered "black". The provided value is scaled according to
4166 the following equation:
4168 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
4171 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
4172 the input video format, the range is [0-255] for YUV full-range
4173 formats and [16-235] for YUV non full-range formats.
4175 Default value is 0.10.
4178 The following example sets the maximum pixel threshold to the minimum
4179 value, and detects only black intervals of 2 or more seconds:
4181 blackdetect=d=2:pix_th=0.00
4186 Detect frames that are (almost) completely black. Can be useful to
4187 detect chapter transitions or commercials. Output lines consist of
4188 the frame number of the detected frame, the percentage of blackness,
4189 the position in the file if known or -1 and the timestamp in seconds.
4191 In order to display the output lines, you need to set the loglevel at
4192 least to the AV_LOG_INFO value.
4194 It accepts the following parameters:
4199 The percentage of the pixels that have to be below the threshold; it defaults to
4202 @item threshold, thresh
4203 The threshold below which a pixel value is considered black; it defaults to
4208 @section blend, tblend
4210 Blend two video frames into each other.
4212 The @code{blend} filter takes two input streams and outputs one
4213 stream, the first input is the "top" layer and second input is
4214 "bottom" layer. Output terminates when shortest input terminates.
4216 The @code{tblend} (time blend) filter takes two consecutive frames
4217 from one single stream, and outputs the result obtained by blending
4218 the new frame on top of the old frame.
4220 A description of the accepted options follows.
4228 Set blend mode for specific pixel component or all pixel components in case
4229 of @var{all_mode}. Default value is @code{normal}.
4231 Available values for component modes are:
4270 Set blend opacity for specific pixel component or all pixel components in case
4271 of @var{all_opacity}. Only used in combination with pixel component blend modes.
4278 Set blend expression for specific pixel component or all pixel components in case
4279 of @var{all_expr}. Note that related mode options will be ignored if those are set.
4281 The expressions can use the following variables:
4285 The sequential number of the filtered frame, starting from @code{0}.
4289 the coordinates of the current sample
4293 the width and height of currently filtered plane
4297 Width and height scale depending on the currently filtered plane. It is the
4298 ratio between the corresponding luma plane number of pixels and the current
4299 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4300 @code{0.5,0.5} for chroma planes.
4303 Time of the current frame, expressed in seconds.
4306 Value of pixel component at current location for first video frame (top layer).
4309 Value of pixel component at current location for second video frame (bottom layer).
4313 Force termination when the shortest input terminates. Default is
4314 @code{0}. This option is only defined for the @code{blend} filter.
4317 Continue applying the last bottom frame after the end of the stream. A value of
4318 @code{0} disable the filter after the last frame of the bottom layer is reached.
4319 Default is @code{1}. This option is only defined for the @code{blend} filter.
4322 @subsection Examples
4326 Apply transition from bottom layer to top layer in first 10 seconds:
4328 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
4332 Apply 1x1 checkerboard effect:
4334 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
4338 Apply uncover left effect:
4340 blend=all_expr='if(gte(N*SW+X,W),A,B)'
4344 Apply uncover down effect:
4346 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
4350 Apply uncover up-left effect:
4352 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
4356 Split diagonally video and shows top and bottom layer on each side:
4358 blend=all_expr=if(gt(X,Y*(W/H)),A,B)
4362 Display differences between the current and the previous frame:
4364 tblend=all_mode=difference128
4370 Deinterlace the input video ("bwdif" stands for "Bob Weaver
4371 Deinterlacing Filter").
4373 Motion adaptive deinterlacing based on yadif with the use of w3fdif and cubic
4374 interpolation algorithms.
4375 It accepts the following parameters:
4379 The interlacing mode to adopt. It accepts one of the following values:
4383 Output one frame for each frame.
4385 Output one frame for each field.
4388 The default value is @code{send_field}.
4391 The picture field parity assumed for the input interlaced video. It accepts one
4392 of the following values:
4396 Assume the top field is first.
4398 Assume the bottom field is first.
4400 Enable automatic detection of field parity.
4403 The default value is @code{auto}.
4404 If the interlacing is unknown or the decoder does not export this information,
4405 top field first will be assumed.
4408 Specify which frames to deinterlace. Accept one of the following
4413 Deinterlace all frames.
4415 Only deinterlace frames marked as interlaced.
4418 The default value is @code{all}.
4423 Apply a boxblur algorithm to the input video.
4425 It accepts the following parameters:
4429 @item luma_radius, lr
4430 @item luma_power, lp
4431 @item chroma_radius, cr
4432 @item chroma_power, cp
4433 @item alpha_radius, ar
4434 @item alpha_power, ap
4438 A description of the accepted options follows.
4441 @item luma_radius, lr
4442 @item chroma_radius, cr
4443 @item alpha_radius, ar
4444 Set an expression for the box radius in pixels used for blurring the
4445 corresponding input plane.
4447 The radius value must be a non-negative number, and must not be
4448 greater than the value of the expression @code{min(w,h)/2} for the
4449 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
4452 Default value for @option{luma_radius} is "2". If not specified,
4453 @option{chroma_radius} and @option{alpha_radius} default to the
4454 corresponding value set for @option{luma_radius}.
4456 The expressions can contain the following constants:
4460 The input width and height in pixels.
4464 The input chroma image width and height in pixels.
4468 The horizontal and vertical chroma subsample values. For example, for the
4469 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
4472 @item luma_power, lp
4473 @item chroma_power, cp
4474 @item alpha_power, ap
4475 Specify how many times the boxblur filter is applied to the
4476 corresponding plane.
4478 Default value for @option{luma_power} is 2. If not specified,
4479 @option{chroma_power} and @option{alpha_power} default to the
4480 corresponding value set for @option{luma_power}.
4482 A value of 0 will disable the effect.
4485 @subsection Examples
4489 Apply a boxblur filter with the luma, chroma, and alpha radii
4492 boxblur=luma_radius=2:luma_power=1
4497 Set the luma radius to 2, and alpha and chroma radius to 0:
4499 boxblur=2:1:cr=0:ar=0
4503 Set the luma and chroma radii to a fraction of the video dimension:
4505 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
4510 YUV colorspace color/chroma keying.
4512 The filter accepts the following options:
4516 The color which will be replaced with transparency.
4519 Similarity percentage with the key color.
4521 0.01 matches only the exact key color, while 1.0 matches everything.
4526 0.0 makes pixels either fully transparent, or not transparent at all.
4528 Higher values result in semi-transparent pixels, with a higher transparency
4529 the more similar the pixels color is to the key color.
4532 Signals that the color passed is already in YUV instead of RGB.
4534 Litteral colors like "green" or "red" don't make sense with this enabled anymore.
4535 This can be used to pass exact YUV values as hexadecimal numbers.
4538 @subsection Examples
4542 Make every green pixel in the input image transparent:
4544 ffmpeg -i input.png -vf chromakey=green out.png
4548 Overlay a greenscreen-video on top of a static black background.
4550 ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.mkv
4556 Visualize information exported by some codecs.
4558 Some codecs can export information through frames using side-data or other
4559 means. For example, some MPEG based codecs export motion vectors through the
4560 @var{export_mvs} flag in the codec @option{flags2} option.
4562 The filter accepts the following option:
4566 Set motion vectors to visualize.
4568 Available flags for @var{mv} are:
4572 forward predicted MVs of P-frames
4574 forward predicted MVs of B-frames
4576 backward predicted MVs of B-frames
4580 Display quantization parameters using the chroma planes
4583 @subsection Examples
4587 Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}:
4589 ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
4593 @section colorbalance
4594 Modify intensity of primary colors (red, green and blue) of input frames.
4596 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
4597 regions for the red-cyan, green-magenta or blue-yellow balance.
4599 A positive adjustment value shifts the balance towards the primary color, a negative
4600 value towards the complementary color.
4602 The filter accepts the following options:
4608 Adjust red, green and blue shadows (darkest pixels).
4613 Adjust red, green and blue midtones (medium pixels).
4618 Adjust red, green and blue highlights (brightest pixels).
4620 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
4623 @subsection Examples
4627 Add red color cast to shadows:
4634 RGB colorspace color keying.
4636 The filter accepts the following options:
4640 The color which will be replaced with transparency.
4643 Similarity percentage with the key color.
4645 0.01 matches only the exact key color, while 1.0 matches everything.
4650 0.0 makes pixels either fully transparent, or not transparent at all.
4652 Higher values result in semi-transparent pixels, with a higher transparency
4653 the more similar the pixels color is to the key color.
4656 @subsection Examples
4660 Make every green pixel in the input image transparent:
4662 ffmpeg -i input.png -vf colorkey=green out.png
4666 Overlay a greenscreen-video on top of a static background image.
4668 ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv
4672 @section colorlevels
4674 Adjust video input frames using levels.
4676 The filter accepts the following options:
4683 Adjust red, green, blue and alpha input black point.
4684 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
4690 Adjust red, green, blue and alpha input white point.
4691 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{1}.
4693 Input levels are used to lighten highlights (bright tones), darken shadows
4694 (dark tones), change the balance of bright and dark tones.
4700 Adjust red, green, blue and alpha output black point.
4701 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{0}.
4707 Adjust red, green, blue and alpha output white point.
4708 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{1}.
4710 Output levels allows manual selection of a constrained output level range.
4713 @subsection Examples
4717 Make video output darker:
4719 colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
4725 colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
4729 Make video output lighter:
4731 colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
4735 Increase brightness:
4737 colorlevels=romin=0.5:gomin=0.5:bomin=0.5
4741 @section colorchannelmixer
4743 Adjust video input frames by re-mixing color channels.
4745 This filter modifies a color channel by adding the values associated to
4746 the other channels of the same pixels. For example if the value to
4747 modify is red, the output value will be:
4749 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
4752 The filter accepts the following options:
4759 Adjust contribution of input red, green, blue and alpha channels for output red channel.
4760 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
4766 Adjust contribution of input red, green, blue and alpha channels for output green channel.
4767 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
4773 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
4774 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
4780 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
4781 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
4783 Allowed ranges for options are @code{[-2.0, 2.0]}.
4786 @subsection Examples
4790 Convert source to grayscale:
4792 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
4795 Simulate sepia tones:
4797 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
4801 @section colormatrix
4803 Convert color matrix.
4805 The filter accepts the following options:
4810 Specify the source and destination color matrix. Both values must be
4813 The accepted values are:
4829 For example to convert from BT.601 to SMPTE-240M, use the command:
4831 colormatrix=bt601:smpte240m
4834 @section convolution
4836 Apply convolution 3x3 or 5x5 filter.
4838 The filter accepts the following options:
4845 Set matrix for each plane.
4846 Matrix is sequence of 9 or 25 signed integers.
4852 Set multiplier for calculated value for each plane.
4858 Set bias for each plane. This value is added to the result of the multiplication.
4859 Useful for making the overall image brighter or darker. Default is 0.0.
4862 @subsection Examples
4868 convolution="0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0"
4874 convolution="1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1/9:1/9:1/9:1/9"
4880 convolution="0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:5:1:1:1:0:128:128:128"
4886 convolution="0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:5:5:5:1:0:128:128:128"
4892 convolution="-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2"
4898 Copy the input source unchanged to the output. This is mainly useful for
4903 Crop the input video to given dimensions.
4905 It accepts the following parameters:
4909 The width of the output video. It defaults to @code{iw}.
4910 This expression is evaluated only once during the filter
4911 configuration, or when the @samp{w} or @samp{out_w} command is sent.
4914 The height of the output video. It defaults to @code{ih}.
4915 This expression is evaluated only once during the filter
4916 configuration, or when the @samp{h} or @samp{out_h} command is sent.
4919 The horizontal position, in the input video, of the left edge of the output
4920 video. It defaults to @code{(in_w-out_w)/2}.
4921 This expression is evaluated per-frame.
4924 The vertical position, in the input video, of the top edge of the output video.
4925 It defaults to @code{(in_h-out_h)/2}.
4926 This expression is evaluated per-frame.
4929 If set to 1 will force the output display aspect ratio
4930 to be the same of the input, by changing the output sample aspect
4931 ratio. It defaults to 0.
4934 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
4935 expressions containing the following constants:
4940 The computed values for @var{x} and @var{y}. They are evaluated for
4945 The input width and height.
4949 These are the same as @var{in_w} and @var{in_h}.
4953 The output (cropped) width and height.
4957 These are the same as @var{out_w} and @var{out_h}.
4960 same as @var{iw} / @var{ih}
4963 input sample aspect ratio
4966 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4970 horizontal and vertical chroma subsample values. For example for the
4971 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4974 The number of the input frame, starting from 0.
4977 the position in the file of the input frame, NAN if unknown
4980 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
4984 The expression for @var{out_w} may depend on the value of @var{out_h},
4985 and the expression for @var{out_h} may depend on @var{out_w}, but they
4986 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
4987 evaluated after @var{out_w} and @var{out_h}.
4989 The @var{x} and @var{y} parameters specify the expressions for the
4990 position of the top-left corner of the output (non-cropped) area. They
4991 are evaluated for each frame. If the evaluated value is not valid, it
4992 is approximated to the nearest valid value.
4994 The expression for @var{x} may depend on @var{y}, and the expression
4995 for @var{y} may depend on @var{x}.
4997 @subsection Examples
5001 Crop area with size 100x100 at position (12,34).
5006 Using named options, the example above becomes:
5008 crop=w=100:h=100:x=12:y=34
5012 Crop the central input area with size 100x100:
5018 Crop the central input area with size 2/3 of the input video:
5020 crop=2/3*in_w:2/3*in_h
5024 Crop the input video central square:
5031 Delimit the rectangle with the top-left corner placed at position
5032 100:100 and the right-bottom corner corresponding to the right-bottom
5033 corner of the input image.
5035 crop=in_w-100:in_h-100:100:100
5039 Crop 10 pixels from the left and right borders, and 20 pixels from
5040 the top and bottom borders
5042 crop=in_w-2*10:in_h-2*20
5046 Keep only the bottom right quarter of the input image:
5048 crop=in_w/2:in_h/2:in_w/2:in_h/2
5052 Crop height for getting Greek harmony:
5054 crop=in_w:1/PHI*in_w
5058 Apply trembling effect:
5060 crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)
5064 Apply erratic camera effect depending on timestamp:
5066 crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
5070 Set x depending on the value of y:
5072 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
5076 @subsection Commands
5078 This filter supports the following commands:
5084 Set width/height of the output video and the horizontal/vertical position
5086 The command accepts the same syntax of the corresponding option.
5088 If the specified expression is not valid, it is kept at its current
5094 Auto-detect the crop size.
5096 It calculates the necessary cropping parameters and prints the
5097 recommended parameters via the logging system. The detected dimensions
5098 correspond to the non-black area of the input video.
5100 It accepts the following parameters:
5105 Set higher black value threshold, which can be optionally specified
5106 from nothing (0) to everything (255 for 8bit based formats). An intensity
5107 value greater to the set value is considered non-black. It defaults to 24.
5108 You can also specify a value between 0.0 and 1.0 which will be scaled depending
5109 on the bitdepth of the pixel format.
5112 The value which the width/height should be divisible by. It defaults to
5113 16. The offset is automatically adjusted to center the video. Use 2 to
5114 get only even dimensions (needed for 4:2:2 video). 16 is best when
5115 encoding to most video codecs.
5117 @item reset_count, reset
5118 Set the counter that determines after how many frames cropdetect will
5119 reset the previously detected largest video area and start over to
5120 detect the current optimal crop area. Default value is 0.
5122 This can be useful when channel logos distort the video area. 0
5123 indicates 'never reset', and returns the largest area encountered during
5130 Apply color adjustments using curves.
5132 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
5133 component (red, green and blue) has its values defined by @var{N} key points
5134 tied from each other using a smooth curve. The x-axis represents the pixel
5135 values from the input frame, and the y-axis the new pixel values to be set for
5138 By default, a component curve is defined by the two points @var{(0;0)} and
5139 @var{(1;1)}. This creates a straight line where each original pixel value is
5140 "adjusted" to its own value, which means no change to the image.
5142 The filter allows you to redefine these two points and add some more. A new
5143 curve (using a natural cubic spline interpolation) will be define to pass
5144 smoothly through all these new coordinates. The new defined points needs to be
5145 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
5146 be in the @var{[0;1]} interval. If the computed curves happened to go outside
5147 the vector spaces, the values will be clipped accordingly.
5149 If there is no key point defined in @code{x=0}, the filter will automatically
5150 insert a @var{(0;0)} point. In the same way, if there is no key point defined
5151 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
5153 The filter accepts the following options:
5157 Select one of the available color presets. This option can be used in addition
5158 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
5159 options takes priority on the preset values.
5160 Available presets are:
5163 @item color_negative
5166 @item increase_contrast
5168 @item linear_contrast
5169 @item medium_contrast
5171 @item strong_contrast
5174 Default is @code{none}.
5176 Set the master key points. These points will define a second pass mapping. It
5177 is sometimes called a "luminance" or "value" mapping. It can be used with
5178 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
5179 post-processing LUT.
5181 Set the key points for the red component.
5183 Set the key points for the green component.
5185 Set the key points for the blue component.
5187 Set the key points for all components (not including master).
5188 Can be used in addition to the other key points component
5189 options. In this case, the unset component(s) will fallback on this
5190 @option{all} setting.
5192 Specify a Photoshop curves file (@code{.acv}) to import the settings from.
5195 To avoid some filtergraph syntax conflicts, each key points list need to be
5196 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
5198 @subsection Examples
5202 Increase slightly the middle level of blue:
5204 curves=blue='0.5/0.58'
5210 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
5212 Here we obtain the following coordinates for each components:
5215 @code{(0;0.11) (0.42;0.51) (1;0.95)}
5217 @code{(0;0) (0.50;0.48) (1;1)}
5219 @code{(0;0.22) (0.49;0.44) (1;0.80)}
5223 The previous example can also be achieved with the associated built-in preset:
5225 curves=preset=vintage
5235 Use a Photoshop preset and redefine the points of the green component:
5237 curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'
5243 Denoise frames using 2D DCT (frequency domain filtering).
5245 This filter is not designed for real time.
5247 The filter accepts the following options:
5251 Set the noise sigma constant.
5253 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
5254 coefficient (absolute value) below this threshold with be dropped.
5256 If you need a more advanced filtering, see @option{expr}.
5258 Default is @code{0}.
5261 Set number overlapping pixels for each block. Since the filter can be slow, you
5262 may want to reduce this value, at the cost of a less effective filter and the
5263 risk of various artefacts.
5265 If the overlapping value doesn't permit processing the whole input width or
5266 height, a warning will be displayed and according borders won't be denoised.
5268 Default value is @var{blocksize}-1, which is the best possible setting.
5271 Set the coefficient factor expression.
5273 For each coefficient of a DCT block, this expression will be evaluated as a
5274 multiplier value for the coefficient.
5276 If this is option is set, the @option{sigma} option will be ignored.
5278 The absolute value of the coefficient can be accessed through the @var{c}
5282 Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the
5283 @var{blocksize}, which is the width and height of the processed blocks.
5285 The default value is @var{3} (8x8) and can be raised to @var{4} for a
5286 @var{blocksize} of 16x16. Note that changing this setting has huge consequences
5287 on the speed processing. Also, a larger block size does not necessarily means a
5291 @subsection Examples
5293 Apply a denoise with a @option{sigma} of @code{4.5}:
5298 The same operation can be achieved using the expression system:
5300 dctdnoiz=e='gte(c, 4.5*3)'
5303 Violent denoise using a block size of @code{16x16}:
5310 Remove banding artifacts from input video.
5311 It works by replacing banded pixels with average value of referenced pixels.
5313 The filter accepts the following options:
5320 Set banding detection threshold for each plane. Default is 0.02.
5321 Valid range is 0.00003 to 0.5.
5322 If difference between current pixel and reference pixel is less than threshold,
5323 it will be considered as banded.
5326 Banding detection range in pixels. Default is 16. If positive, random number
5327 in range 0 to set value will be used. If negative, exact absolute value
5329 The range defines square of four pixels around current pixel.
5332 Set direction in radians from which four pixel will be compared. If positive,
5333 random direction from 0 to set direction will be picked. If negative, exact of
5334 absolute value will be picked. For example direction 0, -PI or -2*PI radians
5335 will pick only pixels on same row and -PI/2 will pick only pixels on same
5339 If enabled, current pixel is compared with average value of all four
5340 surrounding pixels. The default is enabled. If disabled current pixel is
5341 compared with all four surrounding pixels. The pixel is considered banded
5342 if only all four differences with surrounding pixels are less than threshold.
5348 Drop duplicated frames at regular intervals.
5350 The filter accepts the following options:
5354 Set the number of frames from which one will be dropped. Setting this to
5355 @var{N} means one frame in every batch of @var{N} frames will be dropped.
5356 Default is @code{5}.
5359 Set the threshold for duplicate detection. If the difference metric for a frame
5360 is less than or equal to this value, then it is declared as duplicate. Default
5364 Set scene change threshold. Default is @code{15}.
5368 Set the size of the x and y-axis blocks used during metric calculations.
5369 Larger blocks give better noise suppression, but also give worse detection of
5370 small movements. Must be a power of two. Default is @code{32}.
5373 Mark main input as a pre-processed input and activate clean source input
5374 stream. This allows the input to be pre-processed with various filters to help
5375 the metrics calculation while keeping the frame selection lossless. When set to
5376 @code{1}, the first stream is for the pre-processed input, and the second
5377 stream is the clean source from where the kept frames are chosen. Default is
5381 Set whether or not chroma is considered in the metric calculations. Default is
5387 Apply deflate effect to the video.
5389 This filter replaces the pixel by the local(3x3) average by taking into account
5390 only values lower than the pixel.
5392 It accepts the following options:
5399 Limit the maximum change for each plane, default is 65535.
5400 If 0, plane will remain unchanged.
5405 Remove judder produced by partially interlaced telecined content.
5407 Judder can be introduced, for instance, by @ref{pullup} filter. If the original
5408 source was partially telecined content then the output of @code{pullup,dejudder}
5409 will have a variable frame rate. May change the recorded frame rate of the
5410 container. Aside from that change, this filter will not affect constant frame
5413 The option available in this filter is:
5417 Specify the length of the window over which the judder repeats.
5419 Accepts any integer greater than 1. Useful values are:
5423 If the original was telecined from 24 to 30 fps (Film to NTSC).
5426 If the original was telecined from 25 to 30 fps (PAL to NTSC).
5429 If a mixture of the two.
5432 The default is @samp{4}.
5437 Suppress a TV station logo by a simple interpolation of the surrounding
5438 pixels. Just set a rectangle covering the logo and watch it disappear
5439 (and sometimes something even uglier appear - your mileage may vary).
5441 It accepts the following parameters:
5446 Specify the top left corner coordinates of the logo. They must be
5451 Specify the width and height of the logo to clear. They must be
5455 Specify the thickness of the fuzzy edge of the rectangle (added to
5456 @var{w} and @var{h}). The default value is 1. This option is
5457 deprecated, setting higher values should no longer be necessary and
5461 When set to 1, a green rectangle is drawn on the screen to simplify
5462 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
5463 The default value is 0.
5465 The rectangle is drawn on the outermost pixels which will be (partly)
5466 replaced with interpolated values. The values of the next pixels
5467 immediately outside this rectangle in each direction will be used to
5468 compute the interpolated pixel values inside the rectangle.
5472 @subsection Examples
5476 Set a rectangle covering the area with top left corner coordinates 0,0
5477 and size 100x77, and a band of size 10:
5479 delogo=x=0:y=0:w=100:h=77:band=10
5486 Attempt to fix small changes in horizontal and/or vertical shift. This
5487 filter helps remove camera shake from hand-holding a camera, bumping a
5488 tripod, moving on a vehicle, etc.
5490 The filter accepts the following options:
5498 Specify a rectangular area where to limit the search for motion
5500 If desired the search for motion vectors can be limited to a
5501 rectangular area of the frame defined by its top left corner, width
5502 and height. These parameters have the same meaning as the drawbox
5503 filter which can be used to visualise the position of the bounding
5506 This is useful when simultaneous movement of subjects within the frame
5507 might be confused for camera motion by the motion vector search.
5509 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
5510 then the full frame is used. This allows later options to be set
5511 without specifying the bounding box for the motion vector search.
5513 Default - search the whole frame.
5517 Specify the maximum extent of movement in x and y directions in the
5518 range 0-64 pixels. Default 16.
5521 Specify how to generate pixels to fill blanks at the edge of the
5522 frame. Available values are:
5525 Fill zeroes at blank locations
5527 Original image at blank locations
5529 Extruded edge value at blank locations
5531 Mirrored edge at blank locations
5533 Default value is @samp{mirror}.
5536 Specify the blocksize to use for motion search. Range 4-128 pixels,
5540 Specify the contrast threshold for blocks. Only blocks with more than
5541 the specified contrast (difference between darkest and lightest
5542 pixels) will be considered. Range 1-255, default 125.
5545 Specify the search strategy. Available values are:
5548 Set exhaustive search
5550 Set less exhaustive search.
5552 Default value is @samp{exhaustive}.
5555 If set then a detailed log of the motion search is written to the
5559 If set to 1, specify using OpenCL capabilities, only available if
5560 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
5566 Apply an exact inverse of the telecine operation. It requires a predefined
5567 pattern specified using the pattern option which must be the same as that passed
5568 to the telecine filter.
5570 This filter accepts the following options:
5579 The default value is @code{top}.
5583 A string of numbers representing the pulldown pattern you wish to apply.
5584 The default value is @code{23}.
5587 A number representing position of the first frame with respect to the telecine
5588 pattern. This is to be used if the stream is cut. The default value is @code{0}.
5593 Apply dilation effect to the video.
5595 This filter replaces the pixel by the local(3x3) maximum.
5597 It accepts the following options:
5604 Limit the maximum change for each plane, default is 65535.
5605 If 0, plane will remain unchanged.
5608 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
5611 Flags to local 3x3 coordinates maps like this:
5620 Displace pixels as indicated by second and third input stream.
5622 It takes three input streams and outputs one stream, the first input is the
5623 source, and second and third input are displacement maps.
5625 The second input specifies how much to displace pixels along the
5626 x-axis, while the third input specifies how much to displace pixels
5628 If one of displacement map streams terminates, last frame from that
5629 displacement map will be used.
5631 Note that once generated, displacements maps can be reused over and over again.
5633 A description of the accepted options follows.
5637 Set displace behavior for pixels that are out of range.
5639 Available values are:
5642 Missing pixels are replaced by black pixels.
5645 Adjacent pixels will spread out to replace missing pixels.
5648 Out of range pixels are wrapped so they point to pixels of other side.
5650 Default is @samp{smear}.
5654 @subsection Examples
5658 Add ripple effect to rgb input of video size hd720:
5660 ffmpeg -i INPUT -f lavfi -i nullsrc=s=hd720,lutrgb=128:128:128 -f lavfi -i nullsrc=s=hd720,geq='r=128+30*sin(2*PI*X/400+T):g=128+30*sin(2*PI*X/400+T):b=128+30*sin(2*PI*X/400+T)' -lavfi '[0][1][2]displace' OUTPUT
5664 Add wave effect to rgb input of video size hd720:
5666 ffmpeg -i INPUT -f lavfi -i nullsrc=hd720,geq='r=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):g=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):b=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T))' -lavfi '[1]split[x][y],[0][x][y]displace' OUTPUT
5672 Draw a colored box on the input image.
5674 It accepts the following parameters:
5679 The expressions which specify the top left corner coordinates of the box. It defaults to 0.
5683 The expressions which specify the width and height of the box; if 0 they are interpreted as
5684 the input width and height. It defaults to 0.
5687 Specify the color of the box to write. For the general syntax of this option,
5688 check the "Color" section in the ffmpeg-utils manual. If the special
5689 value @code{invert} is used, the box edge color is the same as the
5690 video with inverted luma.
5693 The expression which sets the thickness of the box edge. Default value is @code{3}.
5695 See below for the list of accepted constants.
5698 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
5699 following constants:
5703 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
5707 horizontal and vertical chroma subsample values. For example for the
5708 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5712 The input width and height.
5715 The input sample aspect ratio.
5719 The x and y offset coordinates where the box is drawn.
5723 The width and height of the drawn box.
5726 The thickness of the drawn box.
5728 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
5729 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
5733 @subsection Examples
5737 Draw a black box around the edge of the input image:
5743 Draw a box with color red and an opacity of 50%:
5745 drawbox=10:20:200:60:red@@0.5
5748 The previous example can be specified as:
5750 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
5754 Fill the box with pink color:
5756 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
5760 Draw a 2-pixel red 2.40:1 mask:
5762 drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red
5766 @section drawgraph, adrawgraph
5768 Draw a graph using input video or audio metadata.
5770 It accepts the following parameters:
5774 Set 1st frame metadata key from which metadata values will be used to draw a graph.
5777 Set 1st foreground color expression.
5780 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
5783 Set 2nd foreground color expression.
5786 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
5789 Set 3rd foreground color expression.
5792 Set 4th frame metadata key from which metadata values will be used to draw a graph.
5795 Set 4th foreground color expression.
5798 Set minimal value of metadata value.
5801 Set maximal value of metadata value.
5804 Set graph background color. Default is white.
5809 Available values for mode is:
5816 Default is @code{line}.
5821 Available values for slide is:
5824 Draw new frame when right border is reached.
5827 Replace old columns with new ones.
5830 Scroll from right to left.
5833 Scroll from left to right.
5836 Default is @code{frame}.
5839 Set size of graph video. For the syntax of this option, check the
5840 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
5841 The default value is @code{900x256}.
5843 The foreground color expressions can use the following variables:
5846 Minimal value of metadata value.
5849 Maximal value of metadata value.
5852 Current metadata key value.
5855 The color is defined as 0xAABBGGRR.
5858 Example using metadata from @ref{signalstats} filter:
5860 signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
5863 Example using metadata from @ref{ebur128} filter:
5865 ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
5870 Draw a grid on the input image.
5872 It accepts the following parameters:
5877 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
5881 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
5882 input width and height, respectively, minus @code{thickness}, so image gets
5883 framed. Default to 0.
5886 Specify the color of the grid. For the general syntax of this option,
5887 check the "Color" section in the ffmpeg-utils manual. If the special
5888 value @code{invert} is used, the grid color is the same as the
5889 video with inverted luma.
5892 The expression which sets the thickness of the grid line. Default value is @code{1}.
5894 See below for the list of accepted constants.
5897 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
5898 following constants:
5902 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
5906 horizontal and vertical chroma subsample values. For example for the
5907 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5911 The input grid cell width and height.
5914 The input sample aspect ratio.
5918 The x and y coordinates of some point of grid intersection (meant to configure offset).
5922 The width and height of the drawn cell.
5925 The thickness of the drawn cell.
5927 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
5928 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
5932 @subsection Examples
5936 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
5938 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
5942 Draw a white 3x3 grid with an opacity of 50%:
5944 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
5951 Draw a text string or text from a specified file on top of a video, using the
5952 libfreetype library.
5954 To enable compilation of this filter, you need to configure FFmpeg with
5955 @code{--enable-libfreetype}.
5956 To enable default font fallback and the @var{font} option you need to
5957 configure FFmpeg with @code{--enable-libfontconfig}.
5958 To enable the @var{text_shaping} option, you need to configure FFmpeg with
5959 @code{--enable-libfribidi}.
5963 It accepts the following parameters:
5968 Used to draw a box around text using the background color.
5969 The value must be either 1 (enable) or 0 (disable).
5970 The default value of @var{box} is 0.
5973 Set the width of the border to be drawn around the box using @var{boxcolor}.
5974 The default value of @var{boxborderw} is 0.
5977 The color to be used for drawing box around text. For the syntax of this
5978 option, check the "Color" section in the ffmpeg-utils manual.
5980 The default value of @var{boxcolor} is "white".
5983 Set the width of the border to be drawn around the text using @var{bordercolor}.
5984 The default value of @var{borderw} is 0.
5987 Set the color to be used for drawing border around text. For the syntax of this
5988 option, check the "Color" section in the ffmpeg-utils manual.
5990 The default value of @var{bordercolor} is "black".
5993 Select how the @var{text} is expanded. Can be either @code{none},
5994 @code{strftime} (deprecated) or
5995 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
5999 If true, check and fix text coords to avoid clipping.
6002 The color to be used for drawing fonts. For the syntax of this option, check
6003 the "Color" section in the ffmpeg-utils manual.
6005 The default value of @var{fontcolor} is "black".
6007 @item fontcolor_expr
6008 String which is expanded the same way as @var{text} to obtain dynamic
6009 @var{fontcolor} value. By default this option has empty value and is not
6010 processed. When this option is set, it overrides @var{fontcolor} option.
6013 The font family to be used for drawing text. By default Sans.
6016 The font file to be used for drawing text. The path must be included.
6017 This parameter is mandatory if the fontconfig support is disabled.
6020 This option does not exist, please see the timeline system
6023 Draw the text applying alpha blending. The value can
6024 be either a number between 0.0 and 1.0
6025 The expression accepts the same variables @var{x, y} do.
6026 The default value is 1.
6027 Please see fontcolor_expr
6030 The font size to be used for drawing text.
6031 The default value of @var{fontsize} is 16.
6034 If set to 1, attempt to shape the text (for example, reverse the order of
6035 right-to-left text and join Arabic characters) before drawing it.
6036 Otherwise, just draw the text exactly as given.
6037 By default 1 (if supported).
6040 The flags to be used for loading the fonts.
6042 The flags map the corresponding flags supported by libfreetype, and are
6043 a combination of the following values:
6050 @item vertical_layout
6051 @item force_autohint
6054 @item ignore_global_advance_width
6056 @item ignore_transform
6062 Default value is "default".
6064 For more information consult the documentation for the FT_LOAD_*
6068 The color to be used for drawing a shadow behind the drawn text. For the
6069 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
6071 The default value of @var{shadowcolor} is "black".
6075 The x and y offsets for the text shadow position with respect to the
6076 position of the text. They can be either positive or negative
6077 values. The default value for both is "0".
6080 The starting frame number for the n/frame_num variable. The default value
6084 The size in number of spaces to use for rendering the tab.
6088 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
6089 format. It can be used with or without text parameter. @var{timecode_rate}
6090 option must be specified.
6092 @item timecode_rate, rate, r
6093 Set the timecode frame rate (timecode only).
6096 The text string to be drawn. The text must be a sequence of UTF-8
6098 This parameter is mandatory if no file is specified with the parameter
6102 A text file containing text to be drawn. The text must be a sequence
6103 of UTF-8 encoded characters.
6105 This parameter is mandatory if no text string is specified with the
6106 parameter @var{text}.
6108 If both @var{text} and @var{textfile} are specified, an error is thrown.
6111 If set to 1, the @var{textfile} will be reloaded before each frame.
6112 Be sure to update it atomically, or it may be read partially, or even fail.
6116 The expressions which specify the offsets where text will be drawn
6117 within the video frame. They are relative to the top/left border of the
6120 The default value of @var{x} and @var{y} is "0".
6122 See below for the list of accepted constants and functions.
6125 The parameters for @var{x} and @var{y} are expressions containing the
6126 following constants and functions:
6130 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
6134 horizontal and vertical chroma subsample values. For example for the
6135 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6138 the height of each text line
6146 @item max_glyph_a, ascent
6147 the maximum distance from the baseline to the highest/upper grid
6148 coordinate used to place a glyph outline point, for all the rendered
6150 It is a positive value, due to the grid's orientation with the Y axis
6153 @item max_glyph_d, descent
6154 the maximum distance from the baseline to the lowest grid coordinate
6155 used to place a glyph outline point, for all the rendered glyphs.
6156 This is a negative value, due to the grid's orientation, with the Y axis
6160 maximum glyph height, that is the maximum height for all the glyphs
6161 contained in the rendered text, it is equivalent to @var{ascent} -
6165 maximum glyph width, that is the maximum width for all the glyphs
6166 contained in the rendered text
6169 the number of input frame, starting from 0
6171 @item rand(min, max)
6172 return a random number included between @var{min} and @var{max}
6175 The input sample aspect ratio.
6178 timestamp expressed in seconds, NAN if the input timestamp is unknown
6181 the height of the rendered text
6184 the width of the rendered text
6188 the x and y offset coordinates where the text is drawn.
6190 These parameters allow the @var{x} and @var{y} expressions to refer
6191 each other, so you can for example specify @code{y=x/dar}.
6194 @anchor{drawtext_expansion}
6195 @subsection Text expansion
6197 If @option{expansion} is set to @code{strftime},
6198 the filter recognizes strftime() sequences in the provided text and
6199 expands them accordingly. Check the documentation of strftime(). This
6200 feature is deprecated.
6202 If @option{expansion} is set to @code{none}, the text is printed verbatim.
6204 If @option{expansion} is set to @code{normal} (which is the default),
6205 the following expansion mechanism is used.
6207 The backslash character @samp{\}, followed by any character, always expands to
6208 the second character.
6210 Sequence of the form @code{%@{...@}} are expanded. The text between the
6211 braces is a function name, possibly followed by arguments separated by ':'.
6212 If the arguments contain special characters or delimiters (':' or '@}'),
6213 they should be escaped.
6215 Note that they probably must also be escaped as the value for the
6216 @option{text} option in the filter argument string and as the filter
6217 argument in the filtergraph description, and possibly also for the shell,
6218 that makes up to four levels of escaping; using a text file avoids these
6221 The following functions are available:
6226 The expression evaluation result.
6228 It must take one argument specifying the expression to be evaluated,
6229 which accepts the same constants and functions as the @var{x} and
6230 @var{y} values. Note that not all constants should be used, for
6231 example the text size is not known when evaluating the expression, so
6232 the constants @var{text_w} and @var{text_h} will have an undefined
6235 @item expr_int_format, eif
6236 Evaluate the expression's value and output as formatted integer.
6238 The first argument is the expression to be evaluated, just as for the @var{expr} function.
6239 The second argument specifies the output format. Allowed values are @samp{x},
6240 @samp{X}, @samp{d} and @samp{u}. They are treated exactly as in the
6241 @code{printf} function.
6242 The third parameter is optional and sets the number of positions taken by the output.
6243 It can be used to add padding with zeros from the left.
6246 The time at which the filter is running, expressed in UTC.
6247 It can accept an argument: a strftime() format string.
6250 The time at which the filter is running, expressed in the local time zone.
6251 It can accept an argument: a strftime() format string.
6254 Frame metadata. It must take one argument specifying metadata key.
6257 The frame number, starting from 0.
6260 A 1 character description of the current picture type.
6263 The timestamp of the current frame.
6264 It can take up to three arguments.
6266 The first argument is the format of the timestamp; it defaults to @code{flt}
6267 for seconds as a decimal number with microsecond accuracy; @code{hms} stands
6268 for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy.
6269 @code{gmtime} stands for the timestamp of the frame formatted as UTC time;
6270 @code{localtime} stands for the timestamp of the frame formatted as
6271 local time zone time.
6273 The second argument is an offset added to the timestamp.
6275 If the format is set to @code{localtime} or @code{gmtime},
6276 a third argument may be supplied: a strftime() format string.
6277 By default, @var{YYYY-MM-DD HH:MM:SS} format will be used.
6280 @subsection Examples
6284 Draw "Test Text" with font FreeSerif, using the default values for the
6285 optional parameters.
6288 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
6292 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
6293 and y=50 (counting from the top-left corner of the screen), text is
6294 yellow with a red box around it. Both the text and the box have an
6298 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
6299 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
6302 Note that the double quotes are not necessary if spaces are not used
6303 within the parameter list.
6306 Show the text at the center of the video frame:
6308 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2"
6312 Show a text line sliding from right to left in the last row of the video
6313 frame. The file @file{LONG_LINE} is assumed to contain a single line
6316 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
6320 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
6322 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
6326 Draw a single green letter "g", at the center of the input video.
6327 The glyph baseline is placed at half screen height.
6329 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
6333 Show text for 1 second every 3 seconds:
6335 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
6339 Use fontconfig to set the font. Note that the colons need to be escaped.
6341 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
6345 Print the date of a real-time encoding (see strftime(3)):
6347 drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}'
6351 Show text fading in and out (appearing/disappearing):
6354 DS=1.0 # display start
6355 DE=10.0 # display end
6356 FID=1.5 # fade in duration
6357 FOD=5 # fade out duration
6358 ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%@{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 @}"
6363 For more information about libfreetype, check:
6364 @url{http://www.freetype.org/}.
6366 For more information about fontconfig, check:
6367 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
6369 For more information about libfribidi, check:
6370 @url{http://fribidi.org/}.
6374 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
6376 The filter accepts the following options:
6381 Set low and high threshold values used by the Canny thresholding
6384 The high threshold selects the "strong" edge pixels, which are then
6385 connected through 8-connectivity with the "weak" edge pixels selected
6386 by the low threshold.
6388 @var{low} and @var{high} threshold values must be chosen in the range
6389 [0,1], and @var{low} should be lesser or equal to @var{high}.
6391 Default value for @var{low} is @code{20/255}, and default value for @var{high}
6395 Define the drawing mode.
6399 Draw white/gray wires on black background.
6402 Mix the colors to create a paint/cartoon effect.
6405 Default value is @var{wires}.
6408 @subsection Examples
6412 Standard edge detection with custom values for the hysteresis thresholding:
6414 edgedetect=low=0.1:high=0.4
6418 Painting effect without thresholding:
6420 edgedetect=mode=colormix:high=0
6425 Set brightness, contrast, saturation and approximate gamma adjustment.
6427 The filter accepts the following options:
6431 Set the contrast expression. The value must be a float value in range
6432 @code{-2.0} to @code{2.0}. The default value is "1".
6435 Set the brightness expression. The value must be a float value in
6436 range @code{-1.0} to @code{1.0}. The default value is "0".
6439 Set the saturation expression. The value must be a float in
6440 range @code{0.0} to @code{3.0}. The default value is "1".
6443 Set the gamma expression. The value must be a float in range
6444 @code{0.1} to @code{10.0}. The default value is "1".
6447 Set the gamma expression for red. The value must be a float in
6448 range @code{0.1} to @code{10.0}. The default value is "1".
6451 Set the gamma expression for green. The value must be a float in range
6452 @code{0.1} to @code{10.0}. The default value is "1".
6455 Set the gamma expression for blue. The value must be a float in range
6456 @code{0.1} to @code{10.0}. The default value is "1".
6459 Set the gamma weight expression. It can be used to reduce the effect
6460 of a high gamma value on bright image areas, e.g. keep them from
6461 getting overamplified and just plain white. The value must be a float
6462 in range @code{0.0} to @code{1.0}. A value of @code{0.0} turns the
6463 gamma correction all the way down while @code{1.0} leaves it at its
6464 full strength. Default is "1".
6467 Set when the expressions for brightness, contrast, saturation and
6468 gamma expressions are evaluated.
6470 It accepts the following values:
6473 only evaluate expressions once during the filter initialization or
6474 when a command is processed
6477 evaluate expressions for each incoming frame
6480 Default value is @samp{init}.
6483 The expressions accept the following parameters:
6486 frame count of the input frame starting from 0
6489 byte position of the corresponding packet in the input file, NAN if
6493 frame rate of the input video, NAN if the input frame rate is unknown
6496 timestamp expressed in seconds, NAN if the input timestamp is unknown
6499 @subsection Commands
6500 The filter supports the following commands:
6504 Set the contrast expression.
6507 Set the brightness expression.
6510 Set the saturation expression.
6513 Set the gamma expression.
6516 Set the gamma_r expression.
6519 Set gamma_g expression.
6522 Set gamma_b expression.
6525 Set gamma_weight expression.
6527 The command accepts the same syntax of the corresponding option.
6529 If the specified expression is not valid, it is kept at its current
6536 Apply erosion effect to the video.
6538 This filter replaces the pixel by the local(3x3) minimum.
6540 It accepts the following options:
6547 Limit the maximum change for each plane, default is 65535.
6548 If 0, plane will remain unchanged.
6551 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
6554 Flags to local 3x3 coordinates maps like this:
6561 @section extractplanes
6563 Extract color channel components from input video stream into
6564 separate grayscale video streams.
6566 The filter accepts the following option:
6570 Set plane(s) to extract.
6572 Available values for planes are:
6583 Choosing planes not available in the input will result in an error.
6584 That means you cannot select @code{r}, @code{g}, @code{b} planes
6585 with @code{y}, @code{u}, @code{v} planes at same time.
6588 @subsection Examples
6592 Extract luma, u and v color channel component from input video frame
6593 into 3 grayscale outputs:
6595 ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi
6601 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
6603 For each input image, the filter will compute the optimal mapping from
6604 the input to the output given the codebook length, that is the number
6605 of distinct output colors.
6607 This filter accepts the following options.
6610 @item codebook_length, l
6611 Set codebook length. The value must be a positive integer, and
6612 represents the number of distinct output colors. Default value is 256.
6615 Set the maximum number of iterations to apply for computing the optimal
6616 mapping. The higher the value the better the result and the higher the
6617 computation time. Default value is 1.
6620 Set a random seed, must be an integer included between 0 and
6621 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
6622 will try to use a good random seed on a best effort basis.
6625 Set pal8 output pixel format. This option does not work with codebook
6626 length greater than 256.
6631 Apply a fade-in/out effect to the input video.
6633 It accepts the following parameters:
6637 The effect type can be either "in" for a fade-in, or "out" for a fade-out
6639 Default is @code{in}.
6641 @item start_frame, s
6642 Specify the number of the frame to start applying the fade
6643 effect at. Default is 0.
6646 The number of frames that the fade effect lasts. At the end of the
6647 fade-in effect, the output video will have the same intensity as the input video.
6648 At the end of the fade-out transition, the output video will be filled with the
6649 selected @option{color}.
6653 If set to 1, fade only alpha channel, if one exists on the input.
6656 @item start_time, st
6657 Specify the timestamp (in seconds) of the frame to start to apply the fade
6658 effect. If both start_frame and start_time are specified, the fade will start at
6659 whichever comes last. Default is 0.
6662 The number of seconds for which the fade effect has to last. At the end of the
6663 fade-in effect the output video will have the same intensity as the input video,
6664 at the end of the fade-out transition the output video will be filled with the
6665 selected @option{color}.
6666 If both duration and nb_frames are specified, duration is used. Default is 0
6667 (nb_frames is used by default).
6670 Specify the color of the fade. Default is "black".
6673 @subsection Examples
6677 Fade in the first 30 frames of video:
6682 The command above is equivalent to:
6688 Fade out the last 45 frames of a 200-frame video:
6691 fade=type=out:start_frame=155:nb_frames=45
6695 Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
6697 fade=in:0:25, fade=out:975:25
6701 Make the first 5 frames yellow, then fade in from frame 5-24:
6703 fade=in:5:20:color=yellow
6707 Fade in alpha over first 25 frames of video:
6709 fade=in:0:25:alpha=1
6713 Make the first 5.5 seconds black, then fade in for 0.5 seconds:
6715 fade=t=in:st=5.5:d=0.5
6721 Apply arbitrary expressions to samples in frequency domain
6725 Adjust the dc value (gain) of the luma plane of the image. The filter
6726 accepts an integer value in range @code{0} to @code{1000}. The default
6727 value is set to @code{0}.
6730 Adjust the dc value (gain) of the 1st chroma plane of the image. The
6731 filter accepts an integer value in range @code{0} to @code{1000}. The
6732 default value is set to @code{0}.
6735 Adjust the dc value (gain) of the 2nd chroma plane of the image. The
6736 filter accepts an integer value in range @code{0} to @code{1000}. The
6737 default value is set to @code{0}.
6740 Set the frequency domain weight expression for the luma plane.
6743 Set the frequency domain weight expression for the 1st chroma plane.
6746 Set the frequency domain weight expression for the 2nd chroma plane.
6748 The filter accepts the following variables:
6751 The coordinates of the current sample.
6755 The width and height of the image.
6758 @subsection Examples
6764 fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
6770 fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
6776 fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
6782 fftfilt=dc_Y=0:weight_Y='exp(-4 * ((Y+X)/(W+H)))'
6789 Extract a single field from an interlaced image using stride
6790 arithmetic to avoid wasting CPU time. The output frames are marked as
6793 The filter accepts the following options:
6797 Specify whether to extract the top (if the value is @code{0} or
6798 @code{top}) or the bottom field (if the value is @code{1} or
6804 Create new frames by copying the top and bottom fields from surrounding frames
6805 supplied as numbers by the hint file.
6809 Set file containing hints: absolute/relative frame numbers.
6811 There must be one line for each frame in a clip. Each line must contain two
6812 numbers separated by the comma, optionally followed by @code{-} or @code{+}.
6813 Numbers supplied on each line of file can not be out of [N-1,N+1] where N
6814 is current frame number for @code{absolute} mode or out of [-1, 1] range
6815 for @code{relative} mode. First number tells from which frame to pick up top
6816 field and second number tells from which frame to pick up bottom field.
6818 If optionally followed by @code{+} output frame will be marked as interlaced,
6819 else if followed by @code{-} output frame will be marked as progressive, else
6820 it will be marked same as input frame.
6821 If line starts with @code{#} or @code{;} that line is skipped.
6824 Can be item @code{absolute} or @code{relative}. Default is @code{absolute}.
6827 Example of first several lines of @code{hint} file for @code{relative} mode:
6830 1,0 - # second frame, use third's frame top field and second's frame bottom field
6831 1,0 - # third frame, use fourth's frame top field and third's frame bottom field
6848 Field matching filter for inverse telecine. It is meant to reconstruct the
6849 progressive frames from a telecined stream. The filter does not drop duplicated
6850 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
6851 followed by a decimation filter such as @ref{decimate} in the filtergraph.
6853 The separation of the field matching and the decimation is notably motivated by
6854 the possibility of inserting a de-interlacing filter fallback between the two.
6855 If the source has mixed telecined and real interlaced content,
6856 @code{fieldmatch} will not be able to match fields for the interlaced parts.
6857 But these remaining combed frames will be marked as interlaced, and thus can be
6858 de-interlaced by a later filter such as @ref{yadif} before decimation.
6860 In addition to the various configuration options, @code{fieldmatch} can take an
6861 optional second stream, activated through the @option{ppsrc} option. If
6862 enabled, the frames reconstruction will be based on the fields and frames from
6863 this second stream. This allows the first input to be pre-processed in order to
6864 help the various algorithms of the filter, while keeping the output lossless
6865 (assuming the fields are matched properly). Typically, a field-aware denoiser,
6866 or brightness/contrast adjustments can help.
6868 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
6869 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
6870 which @code{fieldmatch} is based on. While the semantic and usage are very
6871 close, some behaviour and options names can differ.
6873 The @ref{decimate} filter currently only works for constant frame rate input.
6874 If your input has mixed telecined (30fps) and progressive content with a lower
6875 framerate like 24fps use the following filterchain to produce the necessary cfr
6876 stream: @code{dejudder,fps=30000/1001,fieldmatch,decimate}.
6878 The filter accepts the following options:
6882 Specify the assumed field order of the input stream. Available values are:
6886 Auto detect parity (use FFmpeg's internal parity value).
6888 Assume bottom field first.
6890 Assume top field first.
6893 Note that it is sometimes recommended not to trust the parity announced by the
6896 Default value is @var{auto}.
6899 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
6900 sense that it won't risk creating jerkiness due to duplicate frames when
6901 possible, but if there are bad edits or blended fields it will end up
6902 outputting combed frames when a good match might actually exist. On the other
6903 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
6904 but will almost always find a good frame if there is one. The other values are
6905 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
6906 jerkiness and creating duplicate frames versus finding good matches in sections
6907 with bad edits, orphaned fields, blended fields, etc.
6909 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
6911 Available values are:
6915 2-way matching (p/c)
6917 2-way matching, and trying 3rd match if still combed (p/c + n)
6919 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
6921 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
6922 still combed (p/c + n + u/b)
6924 3-way matching (p/c/n)
6926 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
6927 detected as combed (p/c/n + u/b)
6930 The parenthesis at the end indicate the matches that would be used for that
6931 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
6934 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
6937 Default value is @var{pc_n}.
6940 Mark the main input stream as a pre-processed input, and enable the secondary
6941 input stream as the clean source to pick the fields from. See the filter
6942 introduction for more details. It is similar to the @option{clip2} feature from
6945 Default value is @code{0} (disabled).
6948 Set the field to match from. It is recommended to set this to the same value as
6949 @option{order} unless you experience matching failures with that setting. In
6950 certain circumstances changing the field that is used to match from can have a
6951 large impact on matching performance. Available values are:
6955 Automatic (same value as @option{order}).
6957 Match from the bottom field.
6959 Match from the top field.
6962 Default value is @var{auto}.
6965 Set whether or not chroma is included during the match comparisons. In most
6966 cases it is recommended to leave this enabled. You should set this to @code{0}
6967 only if your clip has bad chroma problems such as heavy rainbowing or other
6968 artifacts. Setting this to @code{0} could also be used to speed things up at
6969 the cost of some accuracy.
6971 Default value is @code{1}.
6975 These define an exclusion band which excludes the lines between @option{y0} and
6976 @option{y1} from being included in the field matching decision. An exclusion
6977 band can be used to ignore subtitles, a logo, or other things that may
6978 interfere with the matching. @option{y0} sets the starting scan line and
6979 @option{y1} sets the ending line; all lines in between @option{y0} and
6980 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
6981 @option{y0} and @option{y1} to the same value will disable the feature.
6982 @option{y0} and @option{y1} defaults to @code{0}.
6985 Set the scene change detection threshold as a percentage of maximum change on
6986 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
6987 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
6988 @option{scthresh} is @code{[0.0, 100.0]}.
6990 Default value is @code{12.0}.
6993 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
6994 account the combed scores of matches when deciding what match to use as the
6995 final match. Available values are:
6999 No final matching based on combed scores.
7001 Combed scores are only used when a scene change is detected.
7003 Use combed scores all the time.
7006 Default is @var{sc}.
7009 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
7010 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
7011 Available values are:
7015 No forced calculation.
7017 Force p/c/n calculations.
7019 Force p/c/n/u/b calculations.
7022 Default value is @var{none}.
7025 This is the area combing threshold used for combed frame detection. This
7026 essentially controls how "strong" or "visible" combing must be to be detected.
7027 Larger values mean combing must be more visible and smaller values mean combing
7028 can be less visible or strong and still be detected. Valid settings are from
7029 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
7030 be detected as combed). This is basically a pixel difference value. A good
7031 range is @code{[8, 12]}.
7033 Default value is @code{9}.
7036 Sets whether or not chroma is considered in the combed frame decision. Only
7037 disable this if your source has chroma problems (rainbowing, etc.) that are
7038 causing problems for the combed frame detection with chroma enabled. Actually,
7039 using @option{chroma}=@var{0} is usually more reliable, except for the case
7040 where there is chroma only combing in the source.
7042 Default value is @code{0}.
7046 Respectively set the x-axis and y-axis size of the window used during combed
7047 frame detection. This has to do with the size of the area in which
7048 @option{combpel} pixels are required to be detected as combed for a frame to be
7049 declared combed. See the @option{combpel} parameter description for more info.
7050 Possible values are any number that is a power of 2 starting at 4 and going up
7053 Default value is @code{16}.
7056 The number of combed pixels inside any of the @option{blocky} by
7057 @option{blockx} size blocks on the frame for the frame to be detected as
7058 combed. While @option{cthresh} controls how "visible" the combing must be, this
7059 setting controls "how much" combing there must be in any localized area (a
7060 window defined by the @option{blockx} and @option{blocky} settings) on the
7061 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
7062 which point no frames will ever be detected as combed). This setting is known
7063 as @option{MI} in TFM/VFM vocabulary.
7065 Default value is @code{80}.
7068 @anchor{p/c/n/u/b meaning}
7069 @subsection p/c/n/u/b meaning
7071 @subsubsection p/c/n
7073 We assume the following telecined stream:
7076 Top fields: 1 2 2 3 4
7077 Bottom fields: 1 2 3 4 4
7080 The numbers correspond to the progressive frame the fields relate to. Here, the
7081 first two frames are progressive, the 3rd and 4th are combed, and so on.
7083 When @code{fieldmatch} is configured to run a matching from bottom
7084 (@option{field}=@var{bottom}) this is how this input stream get transformed:
7089 B 1 2 3 4 4 <-- matching reference
7098 As a result of the field matching, we can see that some frames get duplicated.
7099 To perform a complete inverse telecine, you need to rely on a decimation filter
7100 after this operation. See for instance the @ref{decimate} filter.
7102 The same operation now matching from top fields (@option{field}=@var{top})
7107 T 1 2 2 3 4 <-- matching reference
7117 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
7118 basically, they refer to the frame and field of the opposite parity:
7121 @item @var{p} matches the field of the opposite parity in the previous frame
7122 @item @var{c} matches the field of the opposite parity in the current frame
7123 @item @var{n} matches the field of the opposite parity in the next frame
7128 The @var{u} and @var{b} matching are a bit special in the sense that they match
7129 from the opposite parity flag. In the following examples, we assume that we are
7130 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
7131 'x' is placed above and below each matched fields.
7133 With bottom matching (@option{field}=@var{bottom}):
7138 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
7139 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
7147 With top matching (@option{field}=@var{top}):
7152 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
7153 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
7161 @subsection Examples
7163 Simple IVTC of a top field first telecined stream:
7165 fieldmatch=order=tff:combmatch=none, decimate
7168 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
7170 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
7175 Transform the field order of the input video.
7177 It accepts the following parameters:
7182 The output field order. Valid values are @var{tff} for top field first or @var{bff}
7183 for bottom field first.
7186 The default value is @samp{tff}.
7188 The transformation is done by shifting the picture content up or down
7189 by one line, and filling the remaining line with appropriate picture content.
7190 This method is consistent with most broadcast field order converters.
7192 If the input video is not flagged as being interlaced, or it is already
7193 flagged as being of the required output field order, then this filter does
7194 not alter the incoming video.
7196 It is very useful when converting to or from PAL DV material,
7197 which is bottom field first.
7201 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
7204 @section fifo, afifo
7206 Buffer input images and send them when they are requested.
7208 It is mainly useful when auto-inserted by the libavfilter
7211 It does not take parameters.
7215 Find a rectangular object
7217 It accepts the following options:
7221 Filepath of the object image, needs to be in gray8.
7224 Detection threshold, default is 0.5.
7227 Number of mipmaps, default is 3.
7229 @item xmin, ymin, xmax, ymax
7230 Specifies the rectangle in which to search.
7233 @subsection Examples
7237 Generate a representative palette of a given video using @command{ffmpeg}:
7239 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
7245 Cover a rectangular object
7247 It accepts the following options:
7251 Filepath of the optional cover image, needs to be in yuv420.
7256 It accepts the following values:
7259 cover it by the supplied image
7261 cover it by interpolating the surrounding pixels
7264 Default value is @var{blur}.
7267 @subsection Examples
7271 Generate a representative palette of a given video using @command{ffmpeg}:
7273 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
7280 Convert the input video to one of the specified pixel formats.
7281 Libavfilter will try to pick one that is suitable as input to
7284 It accepts the following parameters:
7288 A '|'-separated list of pixel format names, such as
7289 "pix_fmts=yuv420p|monow|rgb24".
7293 @subsection Examples
7297 Convert the input video to the @var{yuv420p} format
7299 format=pix_fmts=yuv420p
7302 Convert the input video to any of the formats in the list
7304 format=pix_fmts=yuv420p|yuv444p|yuv410p
7311 Convert the video to specified constant frame rate by duplicating or dropping
7312 frames as necessary.
7314 It accepts the following parameters:
7318 The desired output frame rate. The default is @code{25}.
7323 Possible values are:
7326 zero round towards 0
7330 round towards -infinity
7332 round towards +infinity
7336 The default is @code{near}.
7339 Assume the first PTS should be the given value, in seconds. This allows for
7340 padding/trimming at the start of stream. By default, no assumption is made
7341 about the first frame's expected PTS, so no padding or trimming is done.
7342 For example, this could be set to 0 to pad the beginning with duplicates of
7343 the first frame if a video stream starts after the audio stream or to trim any
7344 frames with a negative PTS.
7348 Alternatively, the options can be specified as a flat string:
7349 @var{fps}[:@var{round}].
7351 See also the @ref{setpts} filter.
7353 @subsection Examples
7357 A typical usage in order to set the fps to 25:
7363 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
7365 fps=fps=film:round=near
7371 Pack two different video streams into a stereoscopic video, setting proper
7372 metadata on supported codecs. The two views should have the same size and
7373 framerate and processing will stop when the shorter video ends. Please note
7374 that you may conveniently adjust view properties with the @ref{scale} and
7377 It accepts the following parameters:
7381 The desired packing format. Supported values are:
7386 The views are next to each other (default).
7389 The views are on top of each other.
7392 The views are packed by line.
7395 The views are packed by column.
7398 The views are temporally interleaved.
7407 # Convert left and right views into a frame-sequential video
7408 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
7410 # Convert views into a side-by-side video with the same output resolution as the input
7411 ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
7416 Change the frame rate by interpolating new video output frames from the source
7419 This filter is not designed to function correctly with interlaced media. If
7420 you wish to change the frame rate of interlaced media then you are required
7421 to deinterlace before this filter and re-interlace after this filter.
7423 A description of the accepted options follows.
7427 Specify the output frames per second. This option can also be specified
7428 as a value alone. The default is @code{50}.
7431 Specify the start of a range where the output frame will be created as a
7432 linear interpolation of two frames. The range is [@code{0}-@code{255}],
7433 the default is @code{15}.
7436 Specify the end of a range where the output frame will be created as a
7437 linear interpolation of two frames. The range is [@code{0}-@code{255}],
7438 the default is @code{240}.
7441 Specify the level at which a scene change is detected as a value between
7442 0 and 100 to indicate a new scene; a low value reflects a low
7443 probability for the current frame to introduce a new scene, while a higher
7444 value means the current frame is more likely to be one.
7445 The default is @code{7}.
7448 Specify flags influencing the filter process.
7450 Available value for @var{flags} is:
7453 @item scene_change_detect, scd
7454 Enable scene change detection using the value of the option @var{scene}.
7455 This flag is enabled by default.
7461 Select one frame every N-th frame.
7463 This filter accepts the following option:
7466 Select frame after every @code{step} frames.
7467 Allowed values are positive integers higher than 0. Default value is @code{1}.
7473 Apply a frei0r effect to the input video.
7475 To enable the compilation of this filter, you need to install the frei0r
7476 header and configure FFmpeg with @code{--enable-frei0r}.
7478 It accepts the following parameters:
7483 The name of the frei0r effect to load. If the environment variable
7484 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
7485 directories specified by the colon-separated list in @env{FREIOR_PATH}.
7486 Otherwise, the standard frei0r paths are searched, in this order:
7487 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
7488 @file{/usr/lib/frei0r-1/}.
7491 A '|'-separated list of parameters to pass to the frei0r effect.
7495 A frei0r effect parameter can be a boolean (its value is either
7496 "y" or "n"), a double, a color (specified as
7497 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
7498 numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
7499 section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where
7500 @var{X} and @var{Y} are floating point numbers) and/or a string.
7502 The number and types of parameters depend on the loaded effect. If an
7503 effect parameter is not specified, the default value is set.
7505 @subsection Examples
7509 Apply the distort0r effect, setting the first two double parameters:
7511 frei0r=filter_name=distort0r:filter_params=0.5|0.01
7515 Apply the colordistance effect, taking a color as the first parameter:
7517 frei0r=colordistance:0.2/0.3/0.4
7518 frei0r=colordistance:violet
7519 frei0r=colordistance:0x112233
7523 Apply the perspective effect, specifying the top left and top right image
7526 frei0r=perspective:0.2/0.2|0.8/0.2
7530 For more information, see
7531 @url{http://frei0r.dyne.org}
7535 Apply fast and simple postprocessing. It is a faster version of @ref{spp}.
7537 It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
7538 processing filter, one of them is performed once per block, not per pixel.
7539 This allows for much higher speed.
7541 The filter accepts the following options:
7545 Set quality. This option defines the number of levels for averaging. It accepts
7546 an integer in the range 4-5. Default value is @code{4}.
7549 Force a constant quantization parameter. It accepts an integer in range 0-63.
7550 If not set, the filter will use the QP from the video stream (if available).
7553 Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
7554 more details but also more artifacts, while higher values make the image smoother
7555 but also blurrier. Default value is @code{0} − PSNR optimal.
7558 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
7559 option may cause flicker since the B-Frames have often larger QP. Default is
7560 @code{0} (not enabled).
7566 The filter accepts the following options:
7570 Set the luminance expression.
7572 Set the chrominance blue expression.
7574 Set the chrominance red expression.
7576 Set the alpha expression.
7578 Set the red expression.
7580 Set the green expression.
7582 Set the blue expression.
7585 The colorspace is selected according to the specified options. If one
7586 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
7587 options is specified, the filter will automatically select a YCbCr
7588 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
7589 @option{blue_expr} options is specified, it will select an RGB
7592 If one of the chrominance expression is not defined, it falls back on the other
7593 one. If no alpha expression is specified it will evaluate to opaque value.
7594 If none of chrominance expressions are specified, they will evaluate
7595 to the luminance expression.
7597 The expressions can use the following variables and functions:
7601 The sequential number of the filtered frame, starting from @code{0}.
7605 The coordinates of the current sample.
7609 The width and height of the image.
7613 Width and height scale depending on the currently filtered plane. It is the
7614 ratio between the corresponding luma plane number of pixels and the current
7615 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
7616 @code{0.5,0.5} for chroma planes.
7619 Time of the current frame, expressed in seconds.
7622 Return the value of the pixel at location (@var{x},@var{y}) of the current
7626 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
7630 Return the value of the pixel at location (@var{x},@var{y}) of the
7631 blue-difference chroma plane. Return 0 if there is no such plane.
7634 Return the value of the pixel at location (@var{x},@var{y}) of the
7635 red-difference chroma plane. Return 0 if there is no such plane.
7640 Return the value of the pixel at location (@var{x},@var{y}) of the
7641 red/green/blue component. Return 0 if there is no such component.
7644 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
7645 plane. Return 0 if there is no such plane.
7648 For functions, if @var{x} and @var{y} are outside the area, the value will be
7649 automatically clipped to the closer edge.
7651 @subsection Examples
7655 Flip the image horizontally:
7661 Generate a bidimensional sine wave, with angle @code{PI/3} and a
7662 wavelength of 100 pixels:
7664 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
7668 Generate a fancy enigmatic moving light:
7670 nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
7674 Generate a quick emboss effect:
7676 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
7680 Modify RGB components depending on pixel position:
7682 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
7686 Create a radial gradient that is the same size as the input (also see
7687 the @ref{vignette} filter):
7689 geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
7695 Fix the banding artifacts that are sometimes introduced into nearly flat
7696 regions by truncation to 8bit color depth.
7697 Interpolate the gradients that should go where the bands are, and
7700 It is designed for playback only. Do not use it prior to
7701 lossy compression, because compression tends to lose the dither and
7702 bring back the bands.
7704 It accepts the following parameters:
7709 The maximum amount by which the filter will change any one pixel. This is also
7710 the threshold for detecting nearly flat regions. Acceptable values range from
7711 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
7715 The neighborhood to fit the gradient to. A larger radius makes for smoother
7716 gradients, but also prevents the filter from modifying the pixels near detailed
7717 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
7718 values will be clipped to the valid range.
7722 Alternatively, the options can be specified as a flat string:
7723 @var{strength}[:@var{radius}]
7725 @subsection Examples
7729 Apply the filter with a @code{3.5} strength and radius of @code{8}:
7735 Specify radius, omitting the strength (which will fall-back to the default
7746 Apply a Hald CLUT to a video stream.
7748 First input is the video stream to process, and second one is the Hald CLUT.
7749 The Hald CLUT input can be a simple picture or a complete video stream.
7751 The filter accepts the following options:
7755 Force termination when the shortest input terminates. Default is @code{0}.
7757 Continue applying the last CLUT after the end of the stream. A value of
7758 @code{0} disable the filter after the last frame of the CLUT is reached.
7759 Default is @code{1}.
7762 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
7763 filters share the same internals).
7765 More information about the Hald CLUT can be found on Eskil Steenberg's website
7766 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
7768 @subsection Workflow examples
7770 @subsubsection Hald CLUT video stream
7772 Generate an identity Hald CLUT stream altered with various effects:
7774 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut
7777 Note: make sure you use a lossless codec.
7779 Then use it with @code{haldclut} to apply it on some random stream:
7781 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
7784 The Hald CLUT will be applied to the 10 first seconds (duration of
7785 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
7786 to the remaining frames of the @code{mandelbrot} stream.
7788 @subsubsection Hald CLUT with preview
7790 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
7791 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
7792 biggest possible square starting at the top left of the picture. The remaining
7793 padding pixels (bottom or right) will be ignored. This area can be used to add
7794 a preview of the Hald CLUT.
7796 Typically, the following generated Hald CLUT will be supported by the
7797 @code{haldclut} filter:
7800 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
7801 pad=iw+320 [padded_clut];
7802 smptebars=s=320x256, split [a][b];
7803 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
7804 [main][b] overlay=W-320" -frames:v 1 clut.png
7807 It contains the original and a preview of the effect of the CLUT: SMPTE color
7808 bars are displayed on the right-top, and below the same color bars processed by
7811 Then, the effect of this Hald CLUT can be visualized with:
7813 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
7818 Flip the input video horizontally.
7820 For example, to horizontally flip the input video with @command{ffmpeg}:
7822 ffmpeg -i in.avi -vf "hflip" out.avi
7826 This filter applies a global color histogram equalization on a
7829 It can be used to correct video that has a compressed range of pixel
7830 intensities. The filter redistributes the pixel intensities to
7831 equalize their distribution across the intensity range. It may be
7832 viewed as an "automatically adjusting contrast filter". This filter is
7833 useful only for correcting degraded or poorly captured source
7836 The filter accepts the following options:
7840 Determine the amount of equalization to be applied. As the strength
7841 is reduced, the distribution of pixel intensities more-and-more
7842 approaches that of the input frame. The value must be a float number
7843 in the range [0,1] and defaults to 0.200.
7846 Set the maximum intensity that can generated and scale the output
7847 values appropriately. The strength should be set as desired and then
7848 the intensity can be limited if needed to avoid washing-out. The value
7849 must be a float number in the range [0,1] and defaults to 0.210.
7852 Set the antibanding level. If enabled the filter will randomly vary
7853 the luminance of output pixels by a small amount to avoid banding of
7854 the histogram. Possible values are @code{none}, @code{weak} or
7855 @code{strong}. It defaults to @code{none}.
7860 Compute and draw a color distribution histogram for the input video.
7862 The computed histogram is a representation of the color component
7863 distribution in an image.
7865 Standard histogram displays the color components distribution in an image.
7866 Displays color graph for each color component. Shows distribution of
7867 the Y, U, V, A or R, G, B components, depending on input format, in the
7868 current frame. Below each graph a color component scale meter is shown.
7870 The filter accepts the following options:
7874 Set height of level. Default value is @code{200}.
7875 Allowed range is [50, 2048].
7878 Set height of color scale. Default value is @code{12}.
7879 Allowed range is [0, 40].
7883 It accepts the following values:
7886 Per color component graphs are placed below each other.
7889 Presents information identical to that in the @code{parade}, except
7890 that the graphs representing color components are superimposed directly
7893 Default is @code{parade}.
7896 Set mode. Can be either @code{linear}, or @code{logarithmic}.
7897 Default is @code{linear}.
7900 Set what color components to display.
7901 Default is @code{7}.
7904 @subsection Examples
7909 Calculate and draw histogram:
7911 ffplay -i input -vf histogram
7919 This is a high precision/quality 3d denoise filter. It aims to reduce
7920 image noise, producing smooth images and making still images really
7921 still. It should enhance compressibility.
7923 It accepts the following optional parameters:
7927 A non-negative floating point number which specifies spatial luma strength.
7930 @item chroma_spatial
7931 A non-negative floating point number which specifies spatial chroma strength.
7932 It defaults to 3.0*@var{luma_spatial}/4.0.
7935 A floating point number which specifies luma temporal strength. It defaults to
7936 6.0*@var{luma_spatial}/4.0.
7939 A floating point number which specifies chroma temporal strength. It defaults to
7940 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
7945 Apply a high-quality magnification filter designed for pixel art. This filter
7946 was originally created by Maxim Stepin.
7948 It accepts the following option:
7952 Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
7953 @code{hq3x} and @code{4} for @code{hq4x}.
7954 Default is @code{3}.
7958 Stack input videos horizontally.
7960 All streams must be of same pixel format and of same height.
7962 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
7963 to create same output.
7965 The filter accept the following option:
7969 Set number of input streams. Default is 2.
7972 If set to 1, force the output to terminate when the shortest input
7973 terminates. Default value is 0.
7978 Modify the hue and/or the saturation of the input.
7980 It accepts the following parameters:
7984 Specify the hue angle as a number of degrees. It accepts an expression,
7985 and defaults to "0".
7988 Specify the saturation in the [-10,10] range. It accepts an expression and
7992 Specify the hue angle as a number of radians. It accepts an
7993 expression, and defaults to "0".
7996 Specify the brightness in the [-10,10] range. It accepts an expression and
8000 @option{h} and @option{H} are mutually exclusive, and can't be
8001 specified at the same time.
8003 The @option{b}, @option{h}, @option{H} and @option{s} option values are
8004 expressions containing the following constants:
8008 frame count of the input frame starting from 0
8011 presentation timestamp of the input frame expressed in time base units
8014 frame rate of the input video, NAN if the input frame rate is unknown
8017 timestamp expressed in seconds, NAN if the input timestamp is unknown
8020 time base of the input video
8023 @subsection Examples
8027 Set the hue to 90 degrees and the saturation to 1.0:
8033 Same command but expressing the hue in radians:
8039 Rotate hue and make the saturation swing between 0
8040 and 2 over a period of 1 second:
8042 hue="H=2*PI*t: s=sin(2*PI*t)+1"
8046 Apply a 3 seconds saturation fade-in effect starting at 0:
8051 The general fade-in expression can be written as:
8053 hue="s=min(0\, max((t-START)/DURATION\, 1))"
8057 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
8059 hue="s=max(0\, min(1\, (8-t)/3))"
8062 The general fade-out expression can be written as:
8064 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
8069 @subsection Commands
8071 This filter supports the following commands:
8077 Modify the hue and/or the saturation and/or brightness of the input video.
8078 The command accepts the same syntax of the corresponding option.
8080 If the specified expression is not valid, it is kept at its current
8086 Detect video interlacing type.
8088 This filter tries to detect if the input frames as interlaced, progressive,
8089 top or bottom field first. It will also try and detect fields that are
8090 repeated between adjacent frames (a sign of telecine).
8092 Single frame detection considers only immediately adjacent frames when classifying each frame.
8093 Multiple frame detection incorporates the classification history of previous frames.
8095 The filter will log these metadata values:
8098 @item single.current_frame
8099 Detected type of current frame using single-frame detection. One of:
8100 ``tff'' (top field first), ``bff'' (bottom field first),
8101 ``progressive'', or ``undetermined''
8104 Cumulative number of frames detected as top field first using single-frame detection.
8107 Cumulative number of frames detected as top field first using multiple-frame detection.
8110 Cumulative number of frames detected as bottom field first using single-frame detection.
8112 @item multiple.current_frame
8113 Detected type of current frame using multiple-frame detection. One of:
8114 ``tff'' (top field first), ``bff'' (bottom field first),
8115 ``progressive'', or ``undetermined''
8118 Cumulative number of frames detected as bottom field first using multiple-frame detection.
8120 @item single.progressive
8121 Cumulative number of frames detected as progressive using single-frame detection.
8123 @item multiple.progressive
8124 Cumulative number of frames detected as progressive using multiple-frame detection.
8126 @item single.undetermined
8127 Cumulative number of frames that could not be classified using single-frame detection.
8129 @item multiple.undetermined
8130 Cumulative number of frames that could not be classified using multiple-frame detection.
8132 @item repeated.current_frame
8133 Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''.
8135 @item repeated.neither
8136 Cumulative number of frames with no repeated field.
8139 Cumulative number of frames with the top field repeated from the previous frame's top field.
8141 @item repeated.bottom
8142 Cumulative number of frames with the bottom field repeated from the previous frame's bottom field.
8145 The filter accepts the following options:
8149 Set interlacing threshold.
8151 Set progressive threshold.
8153 Threshold for repeated field detection.
8155 Number of frames after which a given frame's contribution to the
8156 statistics is halved (i.e., it contributes only 0.5 to it's
8157 classification). The default of 0 means that all frames seen are given
8158 full weight of 1.0 forever.
8159 @item analyze_interlaced_flag
8160 When this is not 0 then idet will use the specified number of frames to determine
8161 if the interlaced flag is accurate, it will not count undetermined frames.
8162 If the flag is found to be accurate it will be used without any further
8163 computations, if it is found to be inaccurate it will be cleared without any
8164 further computations. This allows inserting the idet filter as a low computational
8165 method to clean up the interlaced flag
8170 Deinterleave or interleave fields.
8172 This filter allows one to process interlaced images fields without
8173 deinterlacing them. Deinterleaving splits the input frame into 2
8174 fields (so called half pictures). Odd lines are moved to the top
8175 half of the output image, even lines to the bottom half.
8176 You can process (filter) them independently and then re-interleave them.
8178 The filter accepts the following options:
8182 @item chroma_mode, c
8184 Available values for @var{luma_mode}, @var{chroma_mode} and
8185 @var{alpha_mode} are:
8191 @item deinterleave, d
8192 Deinterleave fields, placing one above the other.
8195 Interleave fields. Reverse the effect of deinterleaving.
8197 Default value is @code{none}.
8200 @item chroma_swap, cs
8201 @item alpha_swap, as
8202 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
8207 Apply inflate effect to the video.
8209 This filter replaces the pixel by the local(3x3) average by taking into account
8210 only values higher than the pixel.
8212 It accepts the following options:
8219 Limit the maximum change for each plane, default is 65535.
8220 If 0, plane will remain unchanged.
8225 Simple interlacing filter from progressive contents. This interleaves upper (or
8226 lower) lines from odd frames with lower (or upper) lines from even frames,
8227 halving the frame rate and preserving image height.
8230 Original Original New Frame
8231 Frame 'j' Frame 'j+1' (tff)
8232 ========== =========== ==================
8233 Line 0 --------------------> Frame 'j' Line 0
8234 Line 1 Line 1 ----> Frame 'j+1' Line 1
8235 Line 2 ---------------------> Frame 'j' Line 2
8236 Line 3 Line 3 ----> Frame 'j+1' Line 3
8238 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
8241 It accepts the following optional parameters:
8245 This determines whether the interlaced frame is taken from the even
8246 (tff - default) or odd (bff) lines of the progressive frame.
8249 Enable (default) or disable the vertical lowpass filter to avoid twitter
8250 interlacing and reduce moire patterns.
8255 Deinterlace input video by applying Donald Graft's adaptive kernel
8256 deinterling. Work on interlaced parts of a video to produce
8259 The description of the accepted parameters follows.
8263 Set the threshold which affects the filter's tolerance when
8264 determining if a pixel line must be processed. It must be an integer
8265 in the range [0,255] and defaults to 10. A value of 0 will result in
8266 applying the process on every pixels.
8269 Paint pixels exceeding the threshold value to white if set to 1.
8273 Set the fields order. Swap fields if set to 1, leave fields alone if
8277 Enable additional sharpening if set to 1. Default is 0.
8280 Enable twoway sharpening if set to 1. Default is 0.
8283 @subsection Examples
8287 Apply default values:
8289 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
8293 Enable additional sharpening:
8299 Paint processed pixels in white:
8305 @section lenscorrection
8307 Correct radial lens distortion
8309 This filter can be used to correct for radial distortion as can result from the use
8310 of wide angle lenses, and thereby re-rectify the image. To find the right parameters
8311 one can use tools available for example as part of opencv or simply trial-and-error.
8312 To use opencv use the calibration sample (under samples/cpp) from the opencv sources
8313 and extract the k1 and k2 coefficients from the resulting matrix.
8315 Note that effectively the same filter is available in the open-source tools Krita and
8316 Digikam from the KDE project.
8318 In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
8319 this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
8320 brightness distribution, so you may want to use both filters together in certain
8321 cases, though you will have to take care of ordering, i.e. whether vignetting should
8322 be applied before or after lens correction.
8326 The filter accepts the following options:
8330 Relative x-coordinate of the focal point of the image, and thereby the center of the
8331 distortion. This value has a range [0,1] and is expressed as fractions of the image
8334 Relative y-coordinate of the focal point of the image, and thereby the center of the
8335 distortion. This value has a range [0,1] and is expressed as fractions of the image
8338 Coefficient of the quadratic correction term. 0.5 means no correction.
8340 Coefficient of the double quadratic correction term. 0.5 means no correction.
8343 The formula that generates the correction is:
8345 @var{r_src} = @var{r_tgt} * (1 + @var{k1} * (@var{r_tgt} / @var{r_0})^2 + @var{k2} * (@var{r_tgt} / @var{r_0})^4)
8347 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
8348 distances from the focal point in the source and target images, respectively.
8350 @section loop, aloop
8352 Loop video frames or audio samples.
8354 Those filters accepts the following options:
8358 Set the number of loops.
8361 Set maximal size in number of frames for @code{loop} filter or maximal number
8362 of samples in case of @code{aloop} filter.
8365 Set first frame of loop for @code{loop} filter or first sample of loop in case
8366 of @code{aloop} filter.
8372 Apply a 3D LUT to an input video.
8374 The filter accepts the following options:
8378 Set the 3D LUT file name.
8380 Currently supported formats:
8392 Select interpolation mode.
8394 Available values are:
8398 Use values from the nearest defined point.
8400 Interpolate values using the 8 points defining a cube.
8402 Interpolate values using a tetrahedron.
8406 @section lut, lutrgb, lutyuv
8408 Compute a look-up table for binding each pixel component input value
8409 to an output value, and apply it to the input video.
8411 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
8412 to an RGB input video.
8414 These filters accept the following parameters:
8417 set first pixel component expression
8419 set second pixel component expression
8421 set third pixel component expression
8423 set fourth pixel component expression, corresponds to the alpha component
8426 set red component expression
8428 set green component expression
8430 set blue component expression
8432 alpha component expression
8435 set Y/luminance component expression
8437 set U/Cb component expression
8439 set V/Cr component expression
8442 Each of them specifies the expression to use for computing the lookup table for
8443 the corresponding pixel component values.
8445 The exact component associated to each of the @var{c*} options depends on the
8448 The @var{lut} filter requires either YUV or RGB pixel formats in input,
8449 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
8451 The expressions can contain the following constants and functions:
8456 The input width and height.
8459 The input value for the pixel component.
8462 The input value, clipped to the @var{minval}-@var{maxval} range.
8465 The maximum value for the pixel component.
8468 The minimum value for the pixel component.
8471 The negated value for the pixel component value, clipped to the
8472 @var{minval}-@var{maxval} range; it corresponds to the expression
8473 "maxval-clipval+minval".
8476 The computed value in @var{val}, clipped to the
8477 @var{minval}-@var{maxval} range.
8479 @item gammaval(gamma)
8480 The computed gamma correction value of the pixel component value,
8481 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
8483 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
8487 All expressions default to "val".
8489 @subsection Examples
8495 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
8496 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
8499 The above is the same as:
8501 lutrgb="r=negval:g=negval:b=negval"
8502 lutyuv="y=negval:u=negval:v=negval"
8512 Remove chroma components, turning the video into a graytone image:
8514 lutyuv="u=128:v=128"
8518 Apply a luma burning effect:
8524 Remove green and blue components:
8530 Set a constant alpha channel value on input:
8532 format=rgba,lutrgb=a="maxval-minval/2"
8536 Correct luminance gamma by a factor of 0.5:
8538 lutyuv=y=gammaval(0.5)
8542 Discard least significant bits of luma:
8544 lutyuv=y='bitand(val, 128+64+32)'
8548 @section maskedmerge
8550 Merge the first input stream with the second input stream using per pixel
8551 weights in the third input stream.
8553 A value of 0 in the third stream pixel component means that pixel component
8554 from first stream is returned unchanged, while maximum value (eg. 255 for
8555 8-bit videos) means that pixel component from second stream is returned
8556 unchanged. Intermediate values define the amount of merging between both
8557 input stream's pixel components.
8559 This filter accepts the following options:
8562 Set which planes will be processed as bitmap, unprocessed planes will be
8563 copied from first stream.
8564 By default value 0xf, all planes will be processed.
8569 Apply motion-compensation deinterlacing.
8571 It needs one field per frame as input and must thus be used together
8572 with yadif=1/3 or equivalent.
8574 This filter accepts the following options:
8577 Set the deinterlacing mode.
8579 It accepts one of the following values:
8584 use iterative motion estimation
8586 like @samp{slow}, but use multiple reference frames.
8588 Default value is @samp{fast}.
8591 Set the picture field parity assumed for the input video. It must be
8592 one of the following values:
8596 assume top field first
8598 assume bottom field first
8601 Default value is @samp{bff}.
8604 Set per-block quantization parameter (QP) used by the internal
8607 Higher values should result in a smoother motion vector field but less
8608 optimal individual vectors. Default value is 1.
8611 @section mergeplanes
8613 Merge color channel components from several video streams.
8615 The filter accepts up to 4 input streams, and merge selected input
8616 planes to the output video.
8618 This filter accepts the following options:
8621 Set input to output plane mapping. Default is @code{0}.
8623 The mappings is specified as a bitmap. It should be specified as a
8624 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
8625 mapping for the first plane of the output stream. 'A' sets the number of
8626 the input stream to use (from 0 to 3), and 'a' the plane number of the
8627 corresponding input to use (from 0 to 3). The rest of the mappings is
8628 similar, 'Bb' describes the mapping for the output stream second
8629 plane, 'Cc' describes the mapping for the output stream third plane and
8630 'Dd' describes the mapping for the output stream fourth plane.
8633 Set output pixel format. Default is @code{yuva444p}.
8636 @subsection Examples
8640 Merge three gray video streams of same width and height into single video stream:
8642 [a0][a1][a2]mergeplanes=0x001020:yuv444p
8646 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
8648 [a0][a1]mergeplanes=0x00010210:yuva444p
8652 Swap Y and A plane in yuva444p stream:
8654 format=yuva444p,mergeplanes=0x03010200:yuva444p
8658 Swap U and V plane in yuv420p stream:
8660 format=yuv420p,mergeplanes=0x000201:yuv420p
8664 Cast a rgb24 clip to yuv444p:
8666 format=rgb24,mergeplanes=0x000102:yuv444p
8670 @section metadata, ametadata
8672 Manipulate frame metadata.
8674 This filter accepts the following options:
8678 Set mode of operation of the filter.
8680 Can be one of the following:
8684 If both @code{value} and @code{key} is set, select frames
8685 which have such metadata. If only @code{key} is set, select
8686 every frame that has such key in metadata.
8689 Add new metadata @code{key} and @code{value}. If key is already available
8693 Modify value of already present key.
8696 If @code{value} is set, delete only keys that have such value.
8697 Otherwise, delete key.
8700 Print key and its value if metadata was found. If @code{key} is not set print all
8701 metadata values available in frame.
8705 Set key used with all modes. Must be set for all modes except @code{print}.
8708 Set metadata value which will be used. This option is mandatory for
8709 @code{modify} and @code{add} mode.
8712 Which function to use when comparing metadata value and @code{value}.
8714 Can be one of following:
8718 Values are interpreted as strings, returns true if metadata value is same as @code{value}.
8721 Values are interpreted as strings, returns true if metadata value starts with
8722 the @code{value} option string.
8725 Values are interpreted as floats, returns true if metadata value is less than @code{value}.
8728 Values are interpreted as floats, returns true if @code{value} is equal with metadata value.
8731 Values are interpreted as floats, returns true if metadata value is greater than @code{value}.
8734 Values are interpreted as floats, returns true if expression from option @code{expr}
8739 Set expression which is used when @code{function} is set to @code{expr}.
8740 The expression is evaluated through the eval API and can contain the following
8745 Float representation of @code{value} from metadata key.
8748 Float representation of @code{value} as supplied by user in @code{value} option.
8752 If specified in @code{print} mode, output is written to the named file. When
8753 filename equals "-" data is written to standard output.
8754 If @code{file} option is not set, output is written to the log with AV_LOG_INFO
8758 @subsection Examples
8762 Print all metadata values for frames with key @code{lavfi.singnalstats.YDIF} with values
8766 signalstats,metadata=print:key=lavfi.signalstats.YDIF:value=0:function=expr:expr='between(VALUE1,0,1)'
8771 Drop frames that do not differ greatly from the previous frame in
8772 order to reduce frame rate.
8774 The main use of this filter is for very-low-bitrate encoding
8775 (e.g. streaming over dialup modem), but it could in theory be used for
8776 fixing movies that were inverse-telecined incorrectly.
8778 A description of the accepted options follows.
8782 Set the maximum number of consecutive frames which can be dropped (if
8783 positive), or the minimum interval between dropped frames (if
8784 negative). If the value is 0, the frame is dropped unregarding the
8785 number of previous sequentially dropped frames.
8792 Set the dropping threshold values.
8794 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
8795 represent actual pixel value differences, so a threshold of 64
8796 corresponds to 1 unit of difference for each pixel, or the same spread
8797 out differently over the block.
8799 A frame is a candidate for dropping if no 8x8 blocks differ by more
8800 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
8801 meaning the whole image) differ by more than a threshold of @option{lo}.
8803 Default value for @option{hi} is 64*12, default value for @option{lo} is
8804 64*5, and default value for @option{frac} is 0.33.
8812 It accepts an integer in input; if non-zero it negates the
8813 alpha component (if available). The default value in input is 0.
8817 Deinterlace video using neural network edge directed interpolation.
8819 This filter accepts the following options:
8823 Mandatory option, without binary file filter can not work.
8824 Currently file can be found here:
8825 https://github.com/dubhater/vapoursynth-nnedi3/blob/master/src/nnedi3_weights.bin
8828 Set which frames to deinterlace, by default it is @code{all}.
8829 Can be @code{all} or @code{interlaced}.
8832 Set mode of operation.
8834 Can be one of the following:
8838 Use frame flags, both fields.
8840 Use frame flags, single field.
8844 Use bottom field only.
8846 Use both fields, top first.
8848 Use both fields, bottom first.
8852 Set which planes to process, by default filter process all frames.
8855 Set size of local neighborhood around each pixel, used by the predictor neural
8858 Can be one of the following:
8871 Set the number of neurons in predicctor neural network.
8872 Can be one of the following:
8883 Controls the number of different neural network predictions that are blended
8884 together to compute the final output value. Can be @code{fast}, default or
8888 Set which set of weights to use in the predictor.
8889 Can be one of the following:
8893 weights trained to minimize absolute error
8895 weights trained to minimize squared error
8899 Controls whether or not the prescreener neural network is used to decide
8900 which pixels should be processed by the predictor neural network and which
8901 can be handled by simple cubic interpolation.
8902 The prescreener is trained to know whether cubic interpolation will be
8903 sufficient for a pixel or whether it should be predicted by the predictor nn.
8904 The computational complexity of the prescreener nn is much less than that of
8905 the predictor nn. Since most pixels can be handled by cubic interpolation,
8906 using the prescreener generally results in much faster processing.
8907 The prescreener is pretty accurate, so the difference between using it and not
8908 using it is almost always unnoticeable.
8910 Can be one of the following:
8918 Default is @code{new}.
8921 Set various debugging flags.
8926 Force libavfilter not to use any of the specified pixel formats for the
8927 input to the next filter.
8929 It accepts the following parameters:
8933 A '|'-separated list of pixel format names, such as
8934 apix_fmts=yuv420p|monow|rgb24".
8938 @subsection Examples
8942 Force libavfilter to use a format different from @var{yuv420p} for the
8943 input to the vflip filter:
8945 noformat=pix_fmts=yuv420p,vflip
8949 Convert the input video to any of the formats not contained in the list:
8951 noformat=yuv420p|yuv444p|yuv410p
8957 Add noise on video input frame.
8959 The filter accepts the following options:
8967 Set noise seed for specific pixel component or all pixel components in case
8968 of @var{all_seed}. Default value is @code{123457}.
8970 @item all_strength, alls
8971 @item c0_strength, c0s
8972 @item c1_strength, c1s
8973 @item c2_strength, c2s
8974 @item c3_strength, c3s
8975 Set noise strength for specific pixel component or all pixel components in case
8976 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
8978 @item all_flags, allf
8983 Set pixel component flags or set flags for all components if @var{all_flags}.
8984 Available values for component flags are:
8987 averaged temporal noise (smoother)
8989 mix random noise with a (semi)regular pattern
8991 temporal noise (noise pattern changes between frames)
8993 uniform noise (gaussian otherwise)
8997 @subsection Examples
8999 Add temporal and uniform noise to input video:
9001 noise=alls=20:allf=t+u
9006 Pass the video source unchanged to the output.
9009 Optical Character Recognition
9011 This filter uses Tesseract for optical character recognition.
9013 It accepts the following options:
9017 Set datapath to tesseract data. Default is to use whatever was
9018 set at installation.
9021 Set language, default is "eng".
9024 Set character whitelist.
9027 Set character blacklist.
9030 The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
9034 Apply a video transform using libopencv.
9036 To enable this filter, install the libopencv library and headers and
9037 configure FFmpeg with @code{--enable-libopencv}.
9039 It accepts the following parameters:
9044 The name of the libopencv filter to apply.
9047 The parameters to pass to the libopencv filter. If not specified, the default
9052 Refer to the official libopencv documentation for more precise
9054 @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html}
9056 Several libopencv filters are supported; see the following subsections.
9061 Dilate an image by using a specific structuring element.
9062 It corresponds to the libopencv function @code{cvDilate}.
9064 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
9066 @var{struct_el} represents a structuring element, and has the syntax:
9067 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
9069 @var{cols} and @var{rows} represent the number of columns and rows of
9070 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
9071 point, and @var{shape} the shape for the structuring element. @var{shape}
9072 must be "rect", "cross", "ellipse", or "custom".
9074 If the value for @var{shape} is "custom", it must be followed by a
9075 string of the form "=@var{filename}". The file with name
9076 @var{filename} is assumed to represent a binary image, with each
9077 printable character corresponding to a bright pixel. When a custom
9078 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
9079 or columns and rows of the read file are assumed instead.
9081 The default value for @var{struct_el} is "3x3+0x0/rect".
9083 @var{nb_iterations} specifies the number of times the transform is
9084 applied to the image, and defaults to 1.
9088 # Use the default values
9091 # Dilate using a structuring element with a 5x5 cross, iterating two times
9092 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
9094 # Read the shape from the file diamond.shape, iterating two times.
9095 # The file diamond.shape may contain a pattern of characters like this
9101 # The specified columns and rows are ignored
9102 # but the anchor point coordinates are not
9103 ocv=dilate:0x0+2x2/custom=diamond.shape|2
9108 Erode an image by using a specific structuring element.
9109 It corresponds to the libopencv function @code{cvErode}.
9111 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
9112 with the same syntax and semantics as the @ref{dilate} filter.
9116 Smooth the input video.
9118 The filter takes the following parameters:
9119 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
9121 @var{type} is the type of smooth filter to apply, and must be one of
9122 the following values: "blur", "blur_no_scale", "median", "gaussian",
9123 or "bilateral". The default value is "gaussian".
9125 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
9126 depend on the smooth type. @var{param1} and
9127 @var{param2} accept integer positive values or 0. @var{param3} and
9128 @var{param4} accept floating point values.
9130 The default value for @var{param1} is 3. The default value for the
9131 other parameters is 0.
9133 These parameters correspond to the parameters assigned to the
9134 libopencv function @code{cvSmooth}.
9139 Overlay one video on top of another.
9141 It takes two inputs and has one output. The first input is the "main"
9142 video on which the second input is overlaid.
9144 It accepts the following parameters:
9146 A description of the accepted options follows.
9151 Set the expression for the x and y coordinates of the overlaid video
9152 on the main video. Default value is "0" for both expressions. In case
9153 the expression is invalid, it is set to a huge value (meaning that the
9154 overlay will not be displayed within the output visible area).
9157 The action to take when EOF is encountered on the secondary input; it accepts
9158 one of the following values:
9162 Repeat the last frame (the default).
9166 Pass the main input through.
9170 Set when the expressions for @option{x}, and @option{y} are evaluated.
9172 It accepts the following values:
9175 only evaluate expressions once during the filter initialization or
9176 when a command is processed
9179 evaluate expressions for each incoming frame
9182 Default value is @samp{frame}.
9185 If set to 1, force the output to terminate when the shortest input
9186 terminates. Default value is 0.
9189 Set the format for the output video.
9191 It accepts the following values:
9206 Default value is @samp{yuv420}.
9208 @item rgb @emph{(deprecated)}
9209 If set to 1, force the filter to accept inputs in the RGB
9210 color space. Default value is 0. This option is deprecated, use
9211 @option{format} instead.
9214 If set to 1, force the filter to draw the last overlay frame over the
9215 main input until the end of the stream. A value of 0 disables this
9216 behavior. Default value is 1.
9219 The @option{x}, and @option{y} expressions can contain the following
9225 The main input width and height.
9229 The overlay input width and height.
9233 The computed values for @var{x} and @var{y}. They are evaluated for
9238 horizontal and vertical chroma subsample values of the output
9239 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
9243 the number of input frame, starting from 0
9246 the position in the file of the input frame, NAN if unknown
9249 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
9253 Note that the @var{n}, @var{pos}, @var{t} variables are available only
9254 when evaluation is done @emph{per frame}, and will evaluate to NAN
9255 when @option{eval} is set to @samp{init}.
9257 Be aware that frames are taken from each input video in timestamp
9258 order, hence, if their initial timestamps differ, it is a good idea
9259 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
9260 have them begin in the same zero timestamp, as the example for
9261 the @var{movie} filter does.
9263 You can chain together more overlays but you should test the
9264 efficiency of such approach.
9266 @subsection Commands
9268 This filter supports the following commands:
9272 Modify the x and y of the overlay input.
9273 The command accepts the same syntax of the corresponding option.
9275 If the specified expression is not valid, it is kept at its current
9279 @subsection Examples
9283 Draw the overlay at 10 pixels from the bottom right corner of the main
9286 overlay=main_w-overlay_w-10:main_h-overlay_h-10
9289 Using named options the example above becomes:
9291 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
9295 Insert a transparent PNG logo in the bottom left corner of the input,
9296 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
9298 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
9302 Insert 2 different transparent PNG logos (second logo on bottom
9303 right corner) using the @command{ffmpeg} tool:
9305 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
9309 Add a transparent color layer on top of the main video; @code{WxH}
9310 must specify the size of the main input to the overlay filter:
9312 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
9316 Play an original video and a filtered version (here with the deshake
9317 filter) side by side using the @command{ffplay} tool:
9319 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
9322 The above command is the same as:
9324 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
9328 Make a sliding overlay appearing from the left to the right top part of the
9329 screen starting since time 2:
9331 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
9335 Compose output by putting two input videos side to side:
9337 ffmpeg -i left.avi -i right.avi -filter_complex "
9338 nullsrc=size=200x100 [background];
9339 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
9340 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
9341 [background][left] overlay=shortest=1 [background+left];
9342 [background+left][right] overlay=shortest=1:x=100 [left+right]
9347 Mask 10-20 seconds of a video by applying the delogo filter to a section
9349 ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
9350 -vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
9355 Chain several overlays in cascade:
9357 nullsrc=s=200x200 [bg];
9358 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
9359 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
9360 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
9361 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
9362 [in3] null, [mid2] overlay=100:100 [out0]
9369 Apply Overcomplete Wavelet denoiser.
9371 The filter accepts the following options:
9377 Larger depth values will denoise lower frequency components more, but
9378 slow down filtering.
9380 Must be an int in the range 8-16, default is @code{8}.
9382 @item luma_strength, ls
9385 Must be a double value in the range 0-1000, default is @code{1.0}.
9387 @item chroma_strength, cs
9388 Set chroma strength.
9390 Must be a double value in the range 0-1000, default is @code{1.0}.
9396 Add paddings to the input image, and place the original input at the
9397 provided @var{x}, @var{y} coordinates.
9399 It accepts the following parameters:
9404 Specify an expression for the size of the output image with the
9405 paddings added. If the value for @var{width} or @var{height} is 0, the
9406 corresponding input size is used for the output.
9408 The @var{width} expression can reference the value set by the
9409 @var{height} expression, and vice versa.
9411 The default value of @var{width} and @var{height} is 0.
9415 Specify the offsets to place the input image at within the padded area,
9416 with respect to the top/left border of the output image.
9418 The @var{x} expression can reference the value set by the @var{y}
9419 expression, and vice versa.
9421 The default value of @var{x} and @var{y} is 0.
9424 Specify the color of the padded area. For the syntax of this option,
9425 check the "Color" section in the ffmpeg-utils manual.
9427 The default value of @var{color} is "black".
9430 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
9431 options are expressions containing the following constants:
9436 The input video width and height.
9440 These are the same as @var{in_w} and @var{in_h}.
9444 The output width and height (the size of the padded area), as
9445 specified by the @var{width} and @var{height} expressions.
9449 These are the same as @var{out_w} and @var{out_h}.
9453 The x and y offsets as specified by the @var{x} and @var{y}
9454 expressions, or NAN if not yet specified.
9457 same as @var{iw} / @var{ih}
9460 input sample aspect ratio
9463 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
9467 The horizontal and vertical chroma subsample values. For example for the
9468 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9471 @subsection Examples
9475 Add paddings with the color "violet" to the input video. The output video
9476 size is 640x480, and the top-left corner of the input video is placed at
9479 pad=640:480:0:40:violet
9482 The example above is equivalent to the following command:
9484 pad=width=640:height=480:x=0:y=40:color=violet
9488 Pad the input to get an output with dimensions increased by 3/2,
9489 and put the input video at the center of the padded area:
9491 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
9495 Pad the input to get a squared output with size equal to the maximum
9496 value between the input width and height, and put the input video at
9497 the center of the padded area:
9499 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
9503 Pad the input to get a final w/h ratio of 16:9:
9505 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
9509 In case of anamorphic video, in order to set the output display aspect
9510 correctly, it is necessary to use @var{sar} in the expression,
9511 according to the relation:
9513 (ih * X / ih) * sar = output_dar
9514 X = output_dar / sar
9517 Thus the previous example needs to be modified to:
9519 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
9523 Double the output size and put the input video in the bottom-right
9524 corner of the output padded area:
9526 pad="2*iw:2*ih:ow-iw:oh-ih"
9533 Generate one palette for a whole video stream.
9535 It accepts the following options:
9539 Set the maximum number of colors to quantize in the palette.
9540 Note: the palette will still contain 256 colors; the unused palette entries
9543 @item reserve_transparent
9544 Create a palette of 255 colors maximum and reserve the last one for
9545 transparency. Reserving the transparency color is useful for GIF optimization.
9546 If not set, the maximum of colors in the palette will be 256. You probably want
9547 to disable this option for a standalone image.
9551 Set statistics mode.
9553 It accepts the following values:
9556 Compute full frame histograms.
9558 Compute histograms only for the part that differs from previous frame. This
9559 might be relevant to give more importance to the moving part of your input if
9560 the background is static.
9563 Default value is @var{full}.
9566 The filter also exports the frame metadata @code{lavfi.color_quant_ratio}
9567 (@code{nb_color_in / nb_color_out}) which you can use to evaluate the degree of
9568 color quantization of the palette. This information is also visible at
9569 @var{info} logging level.
9571 @subsection Examples
9575 Generate a representative palette of a given video using @command{ffmpeg}:
9577 ffmpeg -i input.mkv -vf palettegen palette.png
9583 Use a palette to downsample an input video stream.
9585 The filter takes two inputs: one video stream and a palette. The palette must
9586 be a 256 pixels image.
9588 It accepts the following options:
9592 Select dithering mode. Available algorithms are:
9595 Ordered 8x8 bayer dithering (deterministic)
9597 Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
9598 Note: this dithering is sometimes considered "wrong" and is included as a
9600 @item floyd_steinberg
9601 Floyd and Steingberg dithering (error diffusion)
9603 Frankie Sierra dithering v2 (error diffusion)
9605 Frankie Sierra dithering v2 "Lite" (error diffusion)
9608 Default is @var{sierra2_4a}.
9611 When @var{bayer} dithering is selected, this option defines the scale of the
9612 pattern (how much the crosshatch pattern is visible). A low value means more
9613 visible pattern for less banding, and higher value means less visible pattern
9614 at the cost of more banding.
9616 The option must be an integer value in the range [0,5]. Default is @var{2}.
9619 If set, define the zone to process
9623 Only the changing rectangle will be reprocessed. This is similar to GIF
9624 cropping/offsetting compression mechanism. This option can be useful for speed
9625 if only a part of the image is changing, and has use cases such as limiting the
9626 scope of the error diffusal @option{dither} to the rectangle that bounds the
9627 moving scene (it leads to more deterministic output if the scene doesn't change
9628 much, and as a result less moving noise and better GIF compression).
9631 Default is @var{none}.
9634 @subsection Examples
9638 Use a palette (generated for example with @ref{palettegen}) to encode a GIF
9639 using @command{ffmpeg}:
9641 ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
9645 @section perspective
9647 Correct perspective of video not recorded perpendicular to the screen.
9649 A description of the accepted parameters follows.
9660 Set coordinates expression for top left, top right, bottom left and bottom right corners.
9661 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
9662 If the @code{sense} option is set to @code{source}, then the specified points will be sent
9663 to the corners of the destination. If the @code{sense} option is set to @code{destination},
9664 then the corners of the source will be sent to the specified coordinates.
9666 The expressions can use the following variables:
9671 the width and height of video frame.
9675 Set interpolation for perspective correction.
9677 It accepts the following values:
9683 Default value is @samp{linear}.
9686 Set interpretation of coordinate options.
9688 It accepts the following values:
9692 Send point in the source specified by the given coordinates to
9693 the corners of the destination.
9695 @item 1, destination
9697 Send the corners of the source to the point in the destination specified
9698 by the given coordinates.
9700 Default value is @samp{source}.
9706 Delay interlaced video by one field time so that the field order changes.
9708 The intended use is to fix PAL movies that have been captured with the
9709 opposite field order to the film-to-video transfer.
9711 A description of the accepted parameters follows.
9717 It accepts the following values:
9720 Capture field order top-first, transfer bottom-first.
9721 Filter will delay the bottom field.
9724 Capture field order bottom-first, transfer top-first.
9725 Filter will delay the top field.
9728 Capture and transfer with the same field order. This mode only exists
9729 for the documentation of the other options to refer to, but if you
9730 actually select it, the filter will faithfully do nothing.
9733 Capture field order determined automatically by field flags, transfer
9735 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
9736 basis using field flags. If no field information is available,
9737 then this works just like @samp{u}.
9740 Capture unknown or varying, transfer opposite.
9741 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
9742 analyzing the images and selecting the alternative that produces best
9743 match between the fields.
9746 Capture top-first, transfer unknown or varying.
9747 Filter selects among @samp{t} and @samp{p} using image analysis.
9750 Capture bottom-first, transfer unknown or varying.
9751 Filter selects among @samp{b} and @samp{p} using image analysis.
9754 Capture determined by field flags, transfer unknown or varying.
9755 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
9756 image analysis. If no field information is available, then this works just
9757 like @samp{U}. This is the default mode.
9760 Both capture and transfer unknown or varying.
9761 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
9765 @section pixdesctest
9767 Pixel format descriptor test filter, mainly useful for internal
9768 testing. The output video should be equal to the input video.
9772 format=monow, pixdesctest
9775 can be used to test the monowhite pixel format descriptor definition.
9779 Enable the specified chain of postprocessing subfilters using libpostproc. This
9780 library should be automatically selected with a GPL build (@code{--enable-gpl}).
9781 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
9782 Each subfilter and some options have a short and a long name that can be used
9783 interchangeably, i.e. dr/dering are the same.
9785 The filters accept the following options:
9789 Set postprocessing subfilters string.
9792 All subfilters share common options to determine their scope:
9796 Honor the quality commands for this subfilter.
9799 Do chrominance filtering, too (default).
9802 Do luminance filtering only (no chrominance).
9805 Do chrominance filtering only (no luminance).
9808 These options can be appended after the subfilter name, separated by a '|'.
9810 Available subfilters are:
9813 @item hb/hdeblock[|difference[|flatness]]
9814 Horizontal deblocking filter
9817 Difference factor where higher values mean more deblocking (default: @code{32}).
9819 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9822 @item vb/vdeblock[|difference[|flatness]]
9823 Vertical deblocking filter
9826 Difference factor where higher values mean more deblocking (default: @code{32}).
9828 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9831 @item ha/hadeblock[|difference[|flatness]]
9832 Accurate horizontal deblocking filter
9835 Difference factor where higher values mean more deblocking (default: @code{32}).
9837 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9840 @item va/vadeblock[|difference[|flatness]]
9841 Accurate vertical deblocking filter
9844 Difference factor where higher values mean more deblocking (default: @code{32}).
9846 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9850 The horizontal and vertical deblocking filters share the difference and
9851 flatness values so you cannot set different horizontal and vertical
9856 Experimental horizontal deblocking filter
9859 Experimental vertical deblocking filter
9864 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
9867 larger -> stronger filtering
9869 larger -> stronger filtering
9871 larger -> stronger filtering
9874 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
9877 Stretch luminance to @code{0-255}.
9880 @item lb/linblenddeint
9881 Linear blend deinterlacing filter that deinterlaces the given block by
9882 filtering all lines with a @code{(1 2 1)} filter.
9884 @item li/linipoldeint
9885 Linear interpolating deinterlacing filter that deinterlaces the given block by
9886 linearly interpolating every second line.
9888 @item ci/cubicipoldeint
9889 Cubic interpolating deinterlacing filter deinterlaces the given block by
9890 cubically interpolating every second line.
9892 @item md/mediandeint
9893 Median deinterlacing filter that deinterlaces the given block by applying a
9894 median filter to every second line.
9896 @item fd/ffmpegdeint
9897 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
9898 second line with a @code{(-1 4 2 4 -1)} filter.
9901 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
9902 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
9904 @item fq/forceQuant[|quantizer]
9905 Overrides the quantizer table from the input with the constant quantizer you
9913 Default pp filter combination (@code{hb|a,vb|a,dr|a})
9916 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
9919 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
9922 @subsection Examples
9926 Apply horizontal and vertical deblocking, deringing and automatic
9927 brightness/contrast:
9933 Apply default filters without brightness/contrast correction:
9939 Apply default filters and temporal denoiser:
9941 pp=default/tmpnoise|1|2|3
9945 Apply deblocking on luminance only, and switch vertical deblocking on or off
9946 automatically depending on available CPU time:
9953 Apply Postprocessing filter 7. It is variant of the @ref{spp} filter,
9954 similar to spp = 6 with 7 point DCT, where only the center sample is
9957 The filter accepts the following options:
9961 Force a constant quantization parameter. It accepts an integer in range
9962 0 to 63. If not set, the filter will use the QP from the video stream
9966 Set thresholding mode. Available modes are:
9970 Set hard thresholding.
9972 Set soft thresholding (better de-ringing effect, but likely blurrier).
9974 Set medium thresholding (good results, default).
9980 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
9981 Ratio) between two input videos.
9983 This filter takes in input two input videos, the first input is
9984 considered the "main" source and is passed unchanged to the
9985 output. The second input is used as a "reference" video for computing
9988 Both video inputs must have the same resolution and pixel format for
9989 this filter to work correctly. Also it assumes that both inputs
9990 have the same number of frames, which are compared one by one.
9992 The obtained average PSNR is printed through the logging system.
9994 The filter stores the accumulated MSE (mean squared error) of each
9995 frame, and at the end of the processing it is averaged across all frames
9996 equally, and the following formula is applied to obtain the PSNR:
9999 PSNR = 10*log10(MAX^2/MSE)
10002 Where MAX is the average of the maximum values of each component of the
10005 The description of the accepted parameters follows.
10008 @item stats_file, f
10009 If specified the filter will use the named file to save the PSNR of
10010 each individual frame. When filename equals "-" the data is sent to
10014 The file printed if @var{stats_file} is selected, contains a sequence of
10015 key/value pairs of the form @var{key}:@var{value} for each compared
10018 A description of each shown parameter follows:
10022 sequential number of the input frame, starting from 1
10025 Mean Square Error pixel-by-pixel average difference of the compared
10026 frames, averaged over all the image components.
10028 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
10029 Mean Square Error pixel-by-pixel average difference of the compared
10030 frames for the component specified by the suffix.
10032 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
10033 Peak Signal to Noise ratio of the compared frames for the component
10034 specified by the suffix.
10039 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
10040 [main][ref] psnr="stats_file=stats.log" [out]
10043 On this example the input file being processed is compared with the
10044 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
10045 is stored in @file{stats.log}.
10050 Pulldown reversal (inverse telecine) filter, capable of handling mixed
10051 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
10054 The pullup filter is designed to take advantage of future context in making
10055 its decisions. This filter is stateless in the sense that it does not lock
10056 onto a pattern to follow, but it instead looks forward to the following
10057 fields in order to identify matches and rebuild progressive frames.
10059 To produce content with an even framerate, insert the fps filter after
10060 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
10061 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
10063 The filter accepts the following options:
10070 These options set the amount of "junk" to ignore at the left, right, top, and
10071 bottom of the image, respectively. Left and right are in units of 8 pixels,
10072 while top and bottom are in units of 2 lines.
10073 The default is 8 pixels on each side.
10076 Set the strict breaks. Setting this option to 1 will reduce the chances of
10077 filter generating an occasional mismatched frame, but it may also cause an
10078 excessive number of frames to be dropped during high motion sequences.
10079 Conversely, setting it to -1 will make filter match fields more easily.
10080 This may help processing of video where there is slight blurring between
10081 the fields, but may also cause there to be interlaced frames in the output.
10082 Default value is @code{0}.
10085 Set the metric plane to use. It accepts the following values:
10091 Use chroma blue plane.
10094 Use chroma red plane.
10097 This option may be set to use chroma plane instead of the default luma plane
10098 for doing filter's computations. This may improve accuracy on very clean
10099 source material, but more likely will decrease accuracy, especially if there
10100 is chroma noise (rainbow effect) or any grayscale video.
10101 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
10102 load and make pullup usable in realtime on slow machines.
10105 For best results (without duplicated frames in the output file) it is
10106 necessary to change the output frame rate. For example, to inverse
10107 telecine NTSC input:
10109 ffmpeg -i input -vf pullup -r 24000/1001 ...
10114 Change video quantization parameters (QP).
10116 The filter accepts the following option:
10120 Set expression for quantization parameter.
10123 The expression is evaluated through the eval API and can contain, among others,
10124 the following constants:
10128 1 if index is not 129, 0 otherwise.
10131 Sequentional index starting from -129 to 128.
10134 @subsection Examples
10138 Some equation like:
10146 Flush video frames from internal cache of frames into a random order.
10147 No frame is discarded.
10148 Inspired by @ref{frei0r} nervous filter.
10152 Set size in number of frames of internal cache, in range from @code{2} to
10153 @code{512}. Default is @code{30}.
10156 Set seed for random number generator, must be an integer included between
10157 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
10158 less than @code{0}, the filter will try to use a good random seed on a
10162 @section removegrain
10164 The removegrain filter is a spatial denoiser for progressive video.
10168 Set mode for the first plane.
10171 Set mode for the second plane.
10174 Set mode for the third plane.
10177 Set mode for the fourth plane.
10180 Range of mode is from 0 to 24. Description of each mode follows:
10184 Leave input plane unchanged. Default.
10187 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
10190 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
10193 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
10196 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
10197 This is equivalent to a median filter.
10200 Line-sensitive clipping giving the minimal change.
10203 Line-sensitive clipping, intermediate.
10206 Line-sensitive clipping, intermediate.
10209 Line-sensitive clipping, intermediate.
10212 Line-sensitive clipping on a line where the neighbours pixels are the closest.
10215 Replaces the target pixel with the closest neighbour.
10218 [1 2 1] horizontal and vertical kernel blur.
10224 Bob mode, interpolates top field from the line where the neighbours
10225 pixels are the closest.
10228 Bob mode, interpolates bottom field from the line where the neighbours
10229 pixels are the closest.
10232 Bob mode, interpolates top field. Same as 13 but with a more complicated
10233 interpolation formula.
10236 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
10237 interpolation formula.
10240 Clips the pixel with the minimum and maximum of respectively the maximum and
10241 minimum of each pair of opposite neighbour pixels.
10244 Line-sensitive clipping using opposite neighbours whose greatest distance from
10245 the current pixel is minimal.
10248 Replaces the pixel with the average of its 8 neighbours.
10251 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
10254 Clips pixels using the averages of opposite neighbour.
10257 Same as mode 21 but simpler and faster.
10260 Small edge and halo removal, but reputed useless.
10266 @section removelogo
10268 Suppress a TV station logo, using an image file to determine which
10269 pixels comprise the logo. It works by filling in the pixels that
10270 comprise the logo with neighboring pixels.
10272 The filter accepts the following options:
10276 Set the filter bitmap file, which can be any image format supported by
10277 libavformat. The width and height of the image file must match those of the
10278 video stream being processed.
10281 Pixels in the provided bitmap image with a value of zero are not
10282 considered part of the logo, non-zero pixels are considered part of
10283 the logo. If you use white (255) for the logo and black (0) for the
10284 rest, you will be safe. For making the filter bitmap, it is
10285 recommended to take a screen capture of a black frame with the logo
10286 visible, and then using a threshold filter followed by the erode
10287 filter once or twice.
10289 If needed, little splotches can be fixed manually. Remember that if
10290 logo pixels are not covered, the filter quality will be much
10291 reduced. Marking too many pixels as part of the logo does not hurt as
10292 much, but it will increase the amount of blurring needed to cover over
10293 the image and will destroy more information than necessary, and extra
10294 pixels will slow things down on a large logo.
10296 @section repeatfields
10298 This filter uses the repeat_field flag from the Video ES headers and hard repeats
10299 fields based on its value.
10301 @section reverse, areverse
10305 Warning: This filter requires memory to buffer the entire clip, so trimming
10308 @subsection Examples
10312 Take the first 5 seconds of a clip, and reverse it.
10320 Rotate video by an arbitrary angle expressed in radians.
10322 The filter accepts the following options:
10324 A description of the optional parameters follows.
10327 Set an expression for the angle by which to rotate the input video
10328 clockwise, expressed as a number of radians. A negative value will
10329 result in a counter-clockwise rotation. By default it is set to "0".
10331 This expression is evaluated for each frame.
10334 Set the output width expression, default value is "iw".
10335 This expression is evaluated just once during configuration.
10338 Set the output height expression, default value is "ih".
10339 This expression is evaluated just once during configuration.
10342 Enable bilinear interpolation if set to 1, a value of 0 disables
10343 it. Default value is 1.
10346 Set the color used to fill the output area not covered by the rotated
10347 image. For the general syntax of this option, check the "Color" section in the
10348 ffmpeg-utils manual. If the special value "none" is selected then no
10349 background is printed (useful for example if the background is never shown).
10351 Default value is "black".
10354 The expressions for the angle and the output size can contain the
10355 following constants and functions:
10359 sequential number of the input frame, starting from 0. It is always NAN
10360 before the first frame is filtered.
10363 time in seconds of the input frame, it is set to 0 when the filter is
10364 configured. It is always NAN before the first frame is filtered.
10368 horizontal and vertical chroma subsample values. For example for the
10369 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10373 the input video width and height
10377 the output width and height, that is the size of the padded area as
10378 specified by the @var{width} and @var{height} expressions
10382 the minimal width/height required for completely containing the input
10383 video rotated by @var{a} radians.
10385 These are only available when computing the @option{out_w} and
10386 @option{out_h} expressions.
10389 @subsection Examples
10393 Rotate the input by PI/6 radians clockwise:
10399 Rotate the input by PI/6 radians counter-clockwise:
10405 Rotate the input by 45 degrees clockwise:
10411 Apply a constant rotation with period T, starting from an angle of PI/3:
10413 rotate=PI/3+2*PI*t/T
10417 Make the input video rotation oscillating with a period of T
10418 seconds and an amplitude of A radians:
10420 rotate=A*sin(2*PI/T*t)
10424 Rotate the video, output size is chosen so that the whole rotating
10425 input video is always completely contained in the output:
10427 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
10431 Rotate the video, reduce the output size so that no background is ever
10434 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
10438 @subsection Commands
10440 The filter supports the following commands:
10444 Set the angle expression.
10445 The command accepts the same syntax of the corresponding option.
10447 If the specified expression is not valid, it is kept at its current
10453 Apply Shape Adaptive Blur.
10455 The filter accepts the following options:
10458 @item luma_radius, lr
10459 Set luma blur filter strength, must be a value in range 0.1-4.0, default
10460 value is 1.0. A greater value will result in a more blurred image, and
10461 in slower processing.
10463 @item luma_pre_filter_radius, lpfr
10464 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
10467 @item luma_strength, ls
10468 Set luma maximum difference between pixels to still be considered, must
10469 be a value in the 0.1-100.0 range, default value is 1.0.
10471 @item chroma_radius, cr
10472 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
10473 greater value will result in a more blurred image, and in slower
10476 @item chroma_pre_filter_radius, cpfr
10477 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
10479 @item chroma_strength, cs
10480 Set chroma maximum difference between pixels to still be considered,
10481 must be a value in the 0.1-100.0 range.
10484 Each chroma option value, if not explicitly specified, is set to the
10485 corresponding luma option value.
10490 Scale (resize) the input video, using the libswscale library.
10492 The scale filter forces the output display aspect ratio to be the same
10493 of the input, by changing the output sample aspect ratio.
10495 If the input image format is different from the format requested by
10496 the next filter, the scale filter will convert the input to the
10499 @subsection Options
10500 The filter accepts the following options, or any of the options
10501 supported by the libswscale scaler.
10503 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
10504 the complete list of scaler options.
10509 Set the output video dimension expression. Default value is the input
10512 If the value is 0, the input width is used for the output.
10514 If one of the values is -1, the scale filter will use a value that
10515 maintains the aspect ratio of the input image, calculated from the
10516 other specified dimension. If both of them are -1, the input size is
10519 If one of the values is -n with n > 1, the scale filter will also use a value
10520 that maintains the aspect ratio of the input image, calculated from the other
10521 specified dimension. After that it will, however, make sure that the calculated
10522 dimension is divisible by n and adjust the value if necessary.
10524 See below for the list of accepted constants for use in the dimension
10528 Specify when to evaluate @var{width} and @var{height} expression. It accepts the following values:
10532 Only evaluate expressions once during the filter initialization or when a command is processed.
10535 Evaluate expressions for each incoming frame.
10539 Default value is @samp{init}.
10543 Set the interlacing mode. It accepts the following values:
10547 Force interlaced aware scaling.
10550 Do not apply interlaced scaling.
10553 Select interlaced aware scaling depending on whether the source frames
10554 are flagged as interlaced or not.
10557 Default value is @samp{0}.
10560 Set libswscale scaling flags. See
10561 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
10562 complete list of values. If not explicitly specified the filter applies
10566 @item param0, param1
10567 Set libswscale input parameters for scaling algorithms that need them. See
10568 @ref{sws_params,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
10569 complete documentation. If not explicitly specified the filter applies
10575 Set the video size. For the syntax of this option, check the
10576 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10578 @item in_color_matrix
10579 @item out_color_matrix
10580 Set in/output YCbCr color space type.
10582 This allows the autodetected value to be overridden as well as allows forcing
10583 a specific value used for the output and encoder.
10585 If not specified, the color space type depends on the pixel format.
10591 Choose automatically.
10594 Format conforming to International Telecommunication Union (ITU)
10595 Recommendation BT.709.
10598 Set color space conforming to the United States Federal Communications
10599 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
10602 Set color space conforming to:
10606 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
10609 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
10612 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
10617 Set color space conforming to SMPTE ST 240:1999.
10622 Set in/output YCbCr sample range.
10624 This allows the autodetected value to be overridden as well as allows forcing
10625 a specific value used for the output and encoder. If not specified, the
10626 range depends on the pixel format. Possible values:
10630 Choose automatically.
10633 Set full range (0-255 in case of 8-bit luma).
10636 Set "MPEG" range (16-235 in case of 8-bit luma).
10639 @item force_original_aspect_ratio
10640 Enable decreasing or increasing output video width or height if necessary to
10641 keep the original aspect ratio. Possible values:
10645 Scale the video as specified and disable this feature.
10648 The output video dimensions will automatically be decreased if needed.
10651 The output video dimensions will automatically be increased if needed.
10655 One useful instance of this option is that when you know a specific device's
10656 maximum allowed resolution, you can use this to limit the output video to
10657 that, while retaining the aspect ratio. For example, device A allows
10658 1280x720 playback, and your video is 1920x800. Using this option (set it to
10659 decrease) and specifying 1280x720 to the command line makes the output
10662 Please note that this is a different thing than specifying -1 for @option{w}
10663 or @option{h}, you still need to specify the output resolution for this option
10668 The values of the @option{w} and @option{h} options are expressions
10669 containing the following constants:
10674 The input width and height
10678 These are the same as @var{in_w} and @var{in_h}.
10682 The output (scaled) width and height
10686 These are the same as @var{out_w} and @var{out_h}
10689 The same as @var{iw} / @var{ih}
10692 input sample aspect ratio
10695 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
10699 horizontal and vertical input chroma subsample values. For example for the
10700 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10704 horizontal and vertical output chroma subsample values. For example for the
10705 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10708 @subsection Examples
10712 Scale the input video to a size of 200x100
10717 This is equivalent to:
10728 Specify a size abbreviation for the output size:
10733 which can also be written as:
10739 Scale the input to 2x:
10741 scale=w=2*iw:h=2*ih
10745 The above is the same as:
10747 scale=2*in_w:2*in_h
10751 Scale the input to 2x with forced interlaced scaling:
10753 scale=2*iw:2*ih:interl=1
10757 Scale the input to half size:
10759 scale=w=iw/2:h=ih/2
10763 Increase the width, and set the height to the same size:
10769 Seek Greek harmony:
10776 Increase the height, and set the width to 3/2 of the height:
10778 scale=w=3/2*oh:h=3/5*ih
10782 Increase the size, making the size a multiple of the chroma
10785 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
10789 Increase the width to a maximum of 500 pixels,
10790 keeping the same aspect ratio as the input:
10792 scale=w='min(500\, iw*3/2):h=-1'
10796 @subsection Commands
10798 This filter supports the following commands:
10802 Set the output video dimension expression.
10803 The command accepts the same syntax of the corresponding option.
10805 If the specified expression is not valid, it is kept at its current
10811 Scale (resize) the input video, based on a reference video.
10813 See the scale filter for available options, scale2ref supports the same but
10814 uses the reference video instead of the main input as basis.
10816 @subsection Examples
10820 Scale a subtitle stream to match the main video in size before overlaying
10822 'scale2ref[b][a];[a][b]overlay'
10826 @section selectivecolor
10828 Adjust cyan, magenta, yellow and black (CMYK) to certain ranges of colors (such
10829 as "reds", "yellows", "greens", "cyans", ...). The adjustment range is defined
10830 by the "purity" of the color (that is, how saturated it already is).
10832 This filter is similar to the Adobe Photoshop Selective Color tool.
10834 The filter accepts the following options:
10837 @item correction_method
10838 Select color correction method.
10840 Available values are:
10843 Specified adjustments are applied "as-is" (added/subtracted to original pixel
10846 Specified adjustments are relative to the original component value.
10848 Default is @code{absolute}.
10850 Adjustments for red pixels (pixels where the red component is the maximum)
10852 Adjustments for yellow pixels (pixels where the blue component is the minimum)
10854 Adjustments for green pixels (pixels where the green component is the maximum)
10856 Adjustments for cyan pixels (pixels where the red component is the minimum)
10858 Adjustments for blue pixels (pixels where the blue component is the maximum)
10860 Adjustments for magenta pixels (pixels where the green component is the minimum)
10862 Adjustments for white pixels (pixels where all components are greater than 128)
10864 Adjustments for all pixels except pure black and pure white
10866 Adjustments for black pixels (pixels where all components are lesser than 128)
10868 Specify a Photoshop selective color file (@code{.asv}) to import the settings from.
10871 All the adjustment settings (@option{reds}, @option{yellows}, ...) accept up to
10872 4 space separated floating point adjustment values in the [-1,1] range,
10873 respectively to adjust the amount of cyan, magenta, yellow and black for the
10874 pixels of its range.
10876 @subsection Examples
10880 Increase cyan by 50% and reduce yellow by 33% in every green areas, and
10881 increase magenta by 27% in blue areas:
10883 selectivecolor=greens=.5 0 -.33 0:blues=0 .27
10887 Use a Photoshop selective color preset:
10889 selectivecolor=psfile=MySelectiveColorPresets/Misty.asv
10893 @section separatefields
10895 The @code{separatefields} takes a frame-based video input and splits
10896 each frame into its components fields, producing a new half height clip
10897 with twice the frame rate and twice the frame count.
10899 This filter use field-dominance information in frame to decide which
10900 of each pair of fields to place first in the output.
10901 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
10903 @section setdar, setsar
10905 The @code{setdar} filter sets the Display Aspect Ratio for the filter
10908 This is done by changing the specified Sample (aka Pixel) Aspect
10909 Ratio, according to the following equation:
10911 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
10914 Keep in mind that the @code{setdar} filter does not modify the pixel
10915 dimensions of the video frame. Also, the display aspect ratio set by
10916 this filter may be changed by later filters in the filterchain,
10917 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
10920 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
10921 the filter output video.
10923 Note that as a consequence of the application of this filter, the
10924 output display aspect ratio will change according to the equation
10927 Keep in mind that the sample aspect ratio set by the @code{setsar}
10928 filter may be changed by later filters in the filterchain, e.g. if
10929 another "setsar" or a "setdar" filter is applied.
10931 It accepts the following parameters:
10934 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
10935 Set the aspect ratio used by the filter.
10937 The parameter can be a floating point number string, an expression, or
10938 a string of the form @var{num}:@var{den}, where @var{num} and
10939 @var{den} are the numerator and denominator of the aspect ratio. If
10940 the parameter is not specified, it is assumed the value "0".
10941 In case the form "@var{num}:@var{den}" is used, the @code{:} character
10945 Set the maximum integer value to use for expressing numerator and
10946 denominator when reducing the expressed aspect ratio to a rational.
10947 Default value is @code{100}.
10951 The parameter @var{sar} is an expression containing
10952 the following constants:
10956 These are approximated values for the mathematical constants e
10957 (Euler's number), pi (Greek pi), and phi (the golden ratio).
10960 The input width and height.
10963 These are the same as @var{w} / @var{h}.
10966 The input sample aspect ratio.
10969 The input display aspect ratio. It is the same as
10970 (@var{w} / @var{h}) * @var{sar}.
10973 Horizontal and vertical chroma subsample values. For example, for the
10974 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10977 @subsection Examples
10982 To change the display aspect ratio to 16:9, specify one of the following:
10990 To change the sample aspect ratio to 10:11, specify:
10996 To set a display aspect ratio of 16:9, and specify a maximum integer value of
10997 1000 in the aspect ratio reduction, use the command:
10999 setdar=ratio=16/9:max=1000
11007 Force field for the output video frame.
11009 The @code{setfield} filter marks the interlace type field for the
11010 output frames. It does not change the input frame, but only sets the
11011 corresponding property, which affects how the frame is treated by
11012 following filters (e.g. @code{fieldorder} or @code{yadif}).
11014 The filter accepts the following options:
11019 Available values are:
11023 Keep the same field property.
11026 Mark the frame as bottom-field-first.
11029 Mark the frame as top-field-first.
11032 Mark the frame as progressive.
11038 Show a line containing various information for each input video frame.
11039 The input video is not modified.
11041 The shown line contains a sequence of key/value pairs of the form
11042 @var{key}:@var{value}.
11044 The following values are shown in the output:
11048 The (sequential) number of the input frame, starting from 0.
11051 The Presentation TimeStamp of the input frame, expressed as a number of
11052 time base units. The time base unit depends on the filter input pad.
11055 The Presentation TimeStamp of the input frame, expressed as a number of
11059 The position of the frame in the input stream, or -1 if this information is
11060 unavailable and/or meaningless (for example in case of synthetic video).
11063 The pixel format name.
11066 The sample aspect ratio of the input frame, expressed in the form
11067 @var{num}/@var{den}.
11070 The size of the input frame. For the syntax of this option, check the
11071 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11074 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
11075 for bottom field first).
11078 This is 1 if the frame is a key frame, 0 otherwise.
11081 The picture type of the input frame ("I" for an I-frame, "P" for a
11082 P-frame, "B" for a B-frame, or "?" for an unknown type).
11083 Also refer to the documentation of the @code{AVPictureType} enum and of
11084 the @code{av_get_picture_type_char} function defined in
11085 @file{libavutil/avutil.h}.
11088 The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
11090 @item plane_checksum
11091 The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
11092 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]".
11095 @section showpalette
11097 Displays the 256 colors palette of each frame. This filter is only relevant for
11098 @var{pal8} pixel format frames.
11100 It accepts the following option:
11104 Set the size of the box used to represent one palette color entry. Default is
11105 @code{30} (for a @code{30x30} pixel box).
11108 @section shuffleframes
11110 Reorder and/or duplicate video frames.
11112 It accepts the following parameters:
11116 Set the destination indexes of input frames.
11117 This is space or '|' separated list of indexes that maps input frames to output
11118 frames. Number of indexes also sets maximal value that each index may have.
11121 The first frame has the index 0. The default is to keep the input unchanged.
11123 Swap second and third frame of every three frames of the input:
11125 ffmpeg -i INPUT -vf "shuffleframes=0 2 1" OUTPUT
11128 @section shuffleplanes
11130 Reorder and/or duplicate video planes.
11132 It accepts the following parameters:
11137 The index of the input plane to be used as the first output plane.
11140 The index of the input plane to be used as the second output plane.
11143 The index of the input plane to be used as the third output plane.
11146 The index of the input plane to be used as the fourth output plane.
11150 The first plane has the index 0. The default is to keep the input unchanged.
11152 Swap the second and third planes of the input:
11154 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
11157 @anchor{signalstats}
11158 @section signalstats
11159 Evaluate various visual metrics that assist in determining issues associated
11160 with the digitization of analog video media.
11162 By default the filter will log these metadata values:
11166 Display the minimal Y value contained within the input frame. Expressed in
11170 Display the Y value at the 10% percentile within the input frame. Expressed in
11174 Display the average Y value within the input frame. Expressed in range of
11178 Display the Y value at the 90% percentile within the input frame. Expressed in
11182 Display the maximum Y value contained within the input frame. Expressed in
11186 Display the minimal U value contained within the input frame. Expressed in
11190 Display the U value at the 10% percentile within the input frame. Expressed in
11194 Display the average U value within the input frame. Expressed in range of
11198 Display the U value at the 90% percentile within the input frame. Expressed in
11202 Display the maximum U value contained within the input frame. Expressed in
11206 Display the minimal V value contained within the input frame. Expressed in
11210 Display the V value at the 10% percentile within the input frame. Expressed in
11214 Display the average V value within the input frame. Expressed in range of
11218 Display the V value at the 90% percentile within the input frame. Expressed in
11222 Display the maximum V value contained within the input frame. Expressed in
11226 Display the minimal saturation value contained within the input frame.
11227 Expressed in range of [0-~181.02].
11230 Display the saturation value at the 10% percentile within the input frame.
11231 Expressed in range of [0-~181.02].
11234 Display the average saturation value within the input frame. Expressed in range
11238 Display the saturation value at the 90% percentile within the input frame.
11239 Expressed in range of [0-~181.02].
11242 Display the maximum saturation value contained within the input frame.
11243 Expressed in range of [0-~181.02].
11246 Display the median value for hue within the input frame. Expressed in range of
11250 Display the average value for hue within the input frame. Expressed in range of
11254 Display the average of sample value difference between all values of the Y
11255 plane in the current frame and corresponding values of the previous input frame.
11256 Expressed in range of [0-255].
11259 Display the average of sample value difference between all values of the U
11260 plane in the current frame and corresponding values of the previous input frame.
11261 Expressed in range of [0-255].
11264 Display the average of sample value difference between all values of the V
11265 plane in the current frame and corresponding values of the previous input frame.
11266 Expressed in range of [0-255].
11269 The filter accepts the following options:
11275 @option{stat} specify an additional form of image analysis.
11276 @option{out} output video with the specified type of pixel highlighted.
11278 Both options accept the following values:
11282 Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel
11283 unlike the neighboring pixels of the same field. Examples of temporal outliers
11284 include the results of video dropouts, head clogs, or tape tracking issues.
11287 Identify @var{vertical line repetition}. Vertical line repetition includes
11288 similar rows of pixels within a frame. In born-digital video vertical line
11289 repetition is common, but this pattern is uncommon in video digitized from an
11290 analog source. When it occurs in video that results from the digitization of an
11291 analog source it can indicate concealment from a dropout compensator.
11294 Identify pixels that fall outside of legal broadcast range.
11298 Set the highlight color for the @option{out} option. The default color is
11302 @subsection Examples
11306 Output data of various video metrics:
11308 ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
11312 Output specific data about the minimum and maximum values of the Y plane per frame:
11314 ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
11318 Playback video while highlighting pixels that are outside of broadcast range in red.
11320 ffplay example.mov -vf signalstats="out=brng:color=red"
11324 Playback video with signalstats metadata drawn over the frame.
11326 ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
11329 The contents of signalstat_drawtext.txt used in the command are:
11332 Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@})
11333 U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@})
11334 V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@})
11335 saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@}
11343 Blur the input video without impacting the outlines.
11345 It accepts the following options:
11348 @item luma_radius, lr
11349 Set the luma radius. The option value must be a float number in
11350 the range [0.1,5.0] that specifies the variance of the gaussian filter
11351 used to blur the image (slower if larger). Default value is 1.0.
11353 @item luma_strength, ls
11354 Set the luma strength. The option value must be a float number
11355 in the range [-1.0,1.0] that configures the blurring. A value included
11356 in [0.0,1.0] will blur the image whereas a value included in
11357 [-1.0,0.0] will sharpen the image. Default value is 1.0.
11359 @item luma_threshold, lt
11360 Set the luma threshold used as a coefficient to determine
11361 whether a pixel should be blurred or not. The option value must be an
11362 integer in the range [-30,30]. A value of 0 will filter all the image,
11363 a value included in [0,30] will filter flat areas and a value included
11364 in [-30,0] will filter edges. Default value is 0.
11366 @item chroma_radius, cr
11367 Set the chroma radius. The option value must be a float number in
11368 the range [0.1,5.0] that specifies the variance of the gaussian filter
11369 used to blur the image (slower if larger). Default value is 1.0.
11371 @item chroma_strength, cs
11372 Set the chroma strength. The option value must be a float number
11373 in the range [-1.0,1.0] that configures the blurring. A value included
11374 in [0.0,1.0] will blur the image whereas a value included in
11375 [-1.0,0.0] will sharpen the image. Default value is 1.0.
11377 @item chroma_threshold, ct
11378 Set the chroma threshold used as a coefficient to determine
11379 whether a pixel should be blurred or not. The option value must be an
11380 integer in the range [-30,30]. A value of 0 will filter all the image,
11381 a value included in [0,30] will filter flat areas and a value included
11382 in [-30,0] will filter edges. Default value is 0.
11385 If a chroma option is not explicitly set, the corresponding luma value
11390 Obtain the SSIM (Structural SImilarity Metric) between two input videos.
11392 This filter takes in input two input videos, the first input is
11393 considered the "main" source and is passed unchanged to the
11394 output. The second input is used as a "reference" video for computing
11397 Both video inputs must have the same resolution and pixel format for
11398 this filter to work correctly. Also it assumes that both inputs
11399 have the same number of frames, which are compared one by one.
11401 The filter stores the calculated SSIM of each frame.
11403 The description of the accepted parameters follows.
11406 @item stats_file, f
11407 If specified the filter will use the named file to save the SSIM of
11408 each individual frame. When filename equals "-" the data is sent to
11412 The file printed if @var{stats_file} is selected, contains a sequence of
11413 key/value pairs of the form @var{key}:@var{value} for each compared
11416 A description of each shown parameter follows:
11420 sequential number of the input frame, starting from 1
11422 @item Y, U, V, R, G, B
11423 SSIM of the compared frames for the component specified by the suffix.
11426 SSIM of the compared frames for the whole frame.
11429 Same as above but in dB representation.
11434 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
11435 [main][ref] ssim="stats_file=stats.log" [out]
11438 On this example the input file being processed is compared with the
11439 reference file @file{ref_movie.mpg}. The SSIM of each individual frame
11440 is stored in @file{stats.log}.
11442 Another example with both psnr and ssim at same time:
11444 ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
11449 Convert between different stereoscopic image formats.
11451 The filters accept the following options:
11455 Set stereoscopic image format of input.
11457 Available values for input image formats are:
11460 side by side parallel (left eye left, right eye right)
11463 side by side crosseye (right eye left, left eye right)
11466 side by side parallel with half width resolution
11467 (left eye left, right eye right)
11470 side by side crosseye with half width resolution
11471 (right eye left, left eye right)
11474 above-below (left eye above, right eye below)
11477 above-below (right eye above, left eye below)
11480 above-below with half height resolution
11481 (left eye above, right eye below)
11484 above-below with half height resolution
11485 (right eye above, left eye below)
11488 alternating frames (left eye first, right eye second)
11491 alternating frames (right eye first, left eye second)
11494 interleaved rows (left eye has top row, right eye starts on next row)
11497 interleaved rows (right eye has top row, left eye starts on next row)
11500 interleaved columns, left eye first
11503 interleaved columns, right eye first
11505 Default value is @samp{sbsl}.
11509 Set stereoscopic image format of output.
11513 side by side parallel (left eye left, right eye right)
11516 side by side crosseye (right eye left, left eye right)
11519 side by side parallel with half width resolution
11520 (left eye left, right eye right)
11523 side by side crosseye with half width resolution
11524 (right eye left, left eye right)
11527 above-below (left eye above, right eye below)
11530 above-below (right eye above, left eye below)
11533 above-below with half height resolution
11534 (left eye above, right eye below)
11537 above-below with half height resolution
11538 (right eye above, left eye below)
11541 alternating frames (left eye first, right eye second)
11544 alternating frames (right eye first, left eye second)
11547 interleaved rows (left eye has top row, right eye starts on next row)
11550 interleaved rows (right eye has top row, left eye starts on next row)
11553 anaglyph red/blue gray
11554 (red filter on left eye, blue filter on right eye)
11557 anaglyph red/green gray
11558 (red filter on left eye, green filter on right eye)
11561 anaglyph red/cyan gray
11562 (red filter on left eye, cyan filter on right eye)
11565 anaglyph red/cyan half colored
11566 (red filter on left eye, cyan filter on right eye)
11569 anaglyph red/cyan color
11570 (red filter on left eye, cyan filter on right eye)
11573 anaglyph red/cyan color optimized with the least squares projection of dubois
11574 (red filter on left eye, cyan filter on right eye)
11577 anaglyph green/magenta gray
11578 (green filter on left eye, magenta filter on right eye)
11581 anaglyph green/magenta half colored
11582 (green filter on left eye, magenta filter on right eye)
11585 anaglyph green/magenta colored
11586 (green filter on left eye, magenta filter on right eye)
11589 anaglyph green/magenta color optimized with the least squares projection of dubois
11590 (green filter on left eye, magenta filter on right eye)
11593 anaglyph yellow/blue gray
11594 (yellow filter on left eye, blue filter on right eye)
11597 anaglyph yellow/blue half colored
11598 (yellow filter on left eye, blue filter on right eye)
11601 anaglyph yellow/blue colored
11602 (yellow filter on left eye, blue filter on right eye)
11605 anaglyph yellow/blue color optimized with the least squares projection of dubois
11606 (yellow filter on left eye, blue filter on right eye)
11609 mono output (left eye only)
11612 mono output (right eye only)
11615 checkerboard, left eye first
11618 checkerboard, right eye first
11621 interleaved columns, left eye first
11624 interleaved columns, right eye first
11627 Default value is @samp{arcd}.
11630 @subsection Examples
11634 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
11640 Convert input video from above below (left eye above, right eye below) to side by side crosseye.
11646 @section streamselect, astreamselect
11647 Select video or audio streams.
11649 The filter accepts the following options:
11653 Set number of inputs. Default is 2.
11656 Set input indexes to remap to outputs.
11659 @subsection Commands
11661 The @code{streamselect} and @code{astreamselect} filter supports the following
11666 Set input indexes to remap to outputs.
11669 @subsection Examples
11673 Select first 5 seconds 1st stream and rest of time 2nd stream:
11675 sendcmd='5.0 streamselect map 1',streamselect=inputs=2:map=0
11679 Same as above, but for audio:
11681 asendcmd='5.0 astreamselect map 1',astreamselect=inputs=2:map=0
11688 Apply a simple postprocessing filter that compresses and decompresses the image
11689 at several (or - in the case of @option{quality} level @code{6} - all) shifts
11690 and average the results.
11692 The filter accepts the following options:
11696 Set quality. This option defines the number of levels for averaging. It accepts
11697 an integer in the range 0-6. If set to @code{0}, the filter will have no
11698 effect. A value of @code{6} means the higher quality. For each increment of
11699 that value the speed drops by a factor of approximately 2. Default value is
11703 Force a constant quantization parameter. If not set, the filter will use the QP
11704 from the video stream (if available).
11707 Set thresholding mode. Available modes are:
11711 Set hard thresholding (default).
11713 Set soft thresholding (better de-ringing effect, but likely blurrier).
11716 @item use_bframe_qp
11717 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
11718 option may cause flicker since the B-Frames have often larger QP. Default is
11719 @code{0} (not enabled).
11725 Draw subtitles on top of input video using the libass library.
11727 To enable compilation of this filter you need to configure FFmpeg with
11728 @code{--enable-libass}. This filter also requires a build with libavcodec and
11729 libavformat to convert the passed subtitles file to ASS (Advanced Substation
11730 Alpha) subtitles format.
11732 The filter accepts the following options:
11736 Set the filename of the subtitle file to read. It must be specified.
11738 @item original_size
11739 Specify the size of the original video, the video for which the ASS file
11740 was composed. For the syntax of this option, check the
11741 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11742 Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
11743 correctly scale the fonts if the aspect ratio has been changed.
11746 Set a directory path containing fonts that can be used by the filter.
11747 These fonts will be used in addition to whatever the font provider uses.
11750 Set subtitles input character encoding. @code{subtitles} filter only. Only
11751 useful if not UTF-8.
11753 @item stream_index, si
11754 Set subtitles stream index. @code{subtitles} filter only.
11757 Override default style or script info parameters of the subtitles. It accepts a
11758 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
11761 If the first key is not specified, it is assumed that the first value
11762 specifies the @option{filename}.
11764 For example, to render the file @file{sub.srt} on top of the input
11765 video, use the command:
11770 which is equivalent to:
11772 subtitles=filename=sub.srt
11775 To render the default subtitles stream from file @file{video.mkv}, use:
11777 subtitles=video.mkv
11780 To render the second subtitles stream from that file, use:
11782 subtitles=video.mkv:si=1
11785 To make the subtitles stream from @file{sub.srt} appear in transparent green
11786 @code{DejaVu Serif}, use:
11788 subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
11791 @section super2xsai
11793 Scale the input by 2x and smooth using the Super2xSaI (Scale and
11794 Interpolate) pixel art scaling algorithm.
11796 Useful for enlarging pixel art images without reducing sharpness.
11800 Swap two rectangular objects in video.
11802 This filter accepts the following options:
11812 Set 1st rect x coordinate.
11815 Set 1st rect y coordinate.
11818 Set 2nd rect x coordinate.
11821 Set 2nd rect y coordinate.
11823 All expressions are evaluated once for each frame.
11826 The all options are expressions containing the following constants:
11831 The input width and height.
11834 same as @var{w} / @var{h}
11837 input sample aspect ratio
11840 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
11843 The number of the input frame, starting from 0.
11846 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
11849 the position in the file of the input frame, NAN if unknown
11857 Apply telecine process to the video.
11859 This filter accepts the following options:
11868 The default value is @code{top}.
11872 A string of numbers representing the pulldown pattern you wish to apply.
11873 The default value is @code{23}.
11877 Some typical patterns:
11882 24p: 2332 (preferred)
11889 24p: 222222222223 ("Euro pulldown")
11895 Select the most representative frame in a given sequence of consecutive frames.
11897 The filter accepts the following options:
11901 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
11902 will pick one of them, and then handle the next batch of @var{n} frames until
11903 the end. Default is @code{100}.
11906 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
11907 value will result in a higher memory usage, so a high value is not recommended.
11909 @subsection Examples
11913 Extract one picture each 50 frames:
11919 Complete example of a thumbnail creation with @command{ffmpeg}:
11921 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
11927 Tile several successive frames together.
11929 The filter accepts the following options:
11934 Set the grid size (i.e. the number of lines and columns). For the syntax of
11935 this option, check the
11936 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11939 Set the maximum number of frames to render in the given area. It must be less
11940 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
11941 the area will be used.
11944 Set the outer border margin in pixels.
11947 Set the inner border thickness (i.e. the number of pixels between frames). For
11948 more advanced padding options (such as having different values for the edges),
11949 refer to the pad video filter.
11952 Specify the color of the unused area. For the syntax of this option, check the
11953 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
11957 @subsection Examples
11961 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
11963 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
11965 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
11966 duplicating each output frame to accommodate the originally detected frame
11970 Display @code{5} pictures in an area of @code{3x2} frames,
11971 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
11972 mixed flat and named options:
11974 tile=3x2:nb_frames=5:padding=7:margin=2
11978 @section tinterlace
11980 Perform various types of temporal field interlacing.
11982 Frames are counted starting from 1, so the first input frame is
11985 The filter accepts the following options:
11990 Specify the mode of the interlacing. This option can also be specified
11991 as a value alone. See below for a list of values for this option.
11993 Available values are:
11997 Move odd frames into the upper field, even into the lower field,
11998 generating a double height frame at half frame rate.
12002 Frame 1 Frame 2 Frame 3 Frame 4
12004 11111 22222 33333 44444
12005 11111 22222 33333 44444
12006 11111 22222 33333 44444
12007 11111 22222 33333 44444
12021 Only output even frames, odd frames are dropped, generating a frame with
12022 unchanged height at half frame rate.
12027 Frame 1 Frame 2 Frame 3 Frame 4
12029 11111 22222 33333 44444
12030 11111 22222 33333 44444
12031 11111 22222 33333 44444
12032 11111 22222 33333 44444
12042 Only output odd frames, even frames are dropped, generating a frame with
12043 unchanged height at half frame rate.
12048 Frame 1 Frame 2 Frame 3 Frame 4
12050 11111 22222 33333 44444
12051 11111 22222 33333 44444
12052 11111 22222 33333 44444
12053 11111 22222 33333 44444
12063 Expand each frame to full height, but pad alternate lines with black,
12064 generating a frame with double height at the same input frame rate.
12069 Frame 1 Frame 2 Frame 3 Frame 4
12071 11111 22222 33333 44444
12072 11111 22222 33333 44444
12073 11111 22222 33333 44444
12074 11111 22222 33333 44444
12077 11111 ..... 33333 .....
12078 ..... 22222 ..... 44444
12079 11111 ..... 33333 .....
12080 ..... 22222 ..... 44444
12081 11111 ..... 33333 .....
12082 ..... 22222 ..... 44444
12083 11111 ..... 33333 .....
12084 ..... 22222 ..... 44444
12088 @item interleave_top, 4
12089 Interleave the upper field from odd frames with the lower field from
12090 even frames, generating a frame with unchanged height at half frame rate.
12095 Frame 1 Frame 2 Frame 3 Frame 4
12097 11111<- 22222 33333<- 44444
12098 11111 22222<- 33333 44444<-
12099 11111<- 22222 33333<- 44444
12100 11111 22222<- 33333 44444<-
12110 @item interleave_bottom, 5
12111 Interleave the lower field from odd frames with the upper field from
12112 even frames, generating a frame with unchanged height at half frame rate.
12117 Frame 1 Frame 2 Frame 3 Frame 4
12119 11111 22222<- 33333 44444<-
12120 11111<- 22222 33333<- 44444
12121 11111 22222<- 33333 44444<-
12122 11111<- 22222 33333<- 44444
12132 @item interlacex2, 6
12133 Double frame rate with unchanged height. Frames are inserted each
12134 containing the second temporal field from the previous input frame and
12135 the first temporal field from the next input frame. This mode relies on
12136 the top_field_first flag. Useful for interlaced video displays with no
12137 field synchronisation.
12142 Frame 1 Frame 2 Frame 3 Frame 4
12144 11111 22222 33333 44444
12145 11111 22222 33333 44444
12146 11111 22222 33333 44444
12147 11111 22222 33333 44444
12150 11111 22222 22222 33333 33333 44444 44444
12151 11111 11111 22222 22222 33333 33333 44444
12152 11111 22222 22222 33333 33333 44444 44444
12153 11111 11111 22222 22222 33333 33333 44444
12157 Move odd frames into the upper field, even into the lower field,
12158 generating a double height frame at same frame rate.
12162 Frame 1 Frame 2 Frame 3 Frame 4
12164 11111 22222 33333 44444
12165 11111 22222 33333 44444
12166 11111 22222 33333 44444
12167 11111 22222 33333 44444
12170 11111 33333 33333 55555
12171 22222 22222 44444 44444
12172 11111 33333 33333 55555
12173 22222 22222 44444 44444
12174 11111 33333 33333 55555
12175 22222 22222 44444 44444
12176 11111 33333 33333 55555
12177 22222 22222 44444 44444
12182 Numeric values are deprecated but are accepted for backward
12183 compatibility reasons.
12185 Default mode is @code{merge}.
12188 Specify flags influencing the filter process.
12190 Available value for @var{flags} is:
12193 @item low_pass_filter, vlfp
12194 Enable vertical low-pass filtering in the filter.
12195 Vertical low-pass filtering is required when creating an interlaced
12196 destination from a progressive source which contains high-frequency
12197 vertical detail. Filtering will reduce interlace 'twitter' and Moire
12200 Vertical low-pass filtering can only be enabled for @option{mode}
12201 @var{interleave_top} and @var{interleave_bottom}.
12208 Transpose rows with columns in the input video and optionally flip it.
12210 It accepts the following parameters:
12215 Specify the transposition direction.
12217 Can assume the following values:
12219 @item 0, 4, cclock_flip
12220 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
12228 Rotate by 90 degrees clockwise, that is:
12236 Rotate by 90 degrees counterclockwise, that is:
12243 @item 3, 7, clock_flip
12244 Rotate by 90 degrees clockwise and vertically flip, that is:
12252 For values between 4-7, the transposition is only done if the input
12253 video geometry is portrait and not landscape. These values are
12254 deprecated, the @code{passthrough} option should be used instead.
12256 Numerical values are deprecated, and should be dropped in favor of
12257 symbolic constants.
12260 Do not apply the transposition if the input geometry matches the one
12261 specified by the specified value. It accepts the following values:
12264 Always apply transposition.
12266 Preserve portrait geometry (when @var{height} >= @var{width}).
12268 Preserve landscape geometry (when @var{width} >= @var{height}).
12271 Default value is @code{none}.
12274 For example to rotate by 90 degrees clockwise and preserve portrait
12277 transpose=dir=1:passthrough=portrait
12280 The command above can also be specified as:
12282 transpose=1:portrait
12286 Trim the input so that the output contains one continuous subpart of the input.
12288 It accepts the following parameters:
12291 Specify the time of the start of the kept section, i.e. the frame with the
12292 timestamp @var{start} will be the first frame in the output.
12295 Specify the time of the first frame that will be dropped, i.e. the frame
12296 immediately preceding the one with the timestamp @var{end} will be the last
12297 frame in the output.
12300 This is the same as @var{start}, except this option sets the start timestamp
12301 in timebase units instead of seconds.
12304 This is the same as @var{end}, except this option sets the end timestamp
12305 in timebase units instead of seconds.
12308 The maximum duration of the output in seconds.
12311 The number of the first frame that should be passed to the output.
12314 The number of the first frame that should be dropped.
12317 @option{start}, @option{end}, and @option{duration} are expressed as time
12318 duration specifications; see
12319 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12320 for the accepted syntax.
12322 Note that the first two sets of the start/end options and the @option{duration}
12323 option look at the frame timestamp, while the _frame variants simply count the
12324 frames that pass through the filter. Also note that this filter does not modify
12325 the timestamps. If you wish for the output timestamps to start at zero, insert a
12326 setpts filter after the trim filter.
12328 If multiple start or end options are set, this filter tries to be greedy and
12329 keep all the frames that match at least one of the specified constraints. To keep
12330 only the part that matches all the constraints at once, chain multiple trim
12333 The defaults are such that all the input is kept. So it is possible to set e.g.
12334 just the end values to keep everything before the specified time.
12339 Drop everything except the second minute of input:
12341 ffmpeg -i INPUT -vf trim=60:120
12345 Keep only the first second:
12347 ffmpeg -i INPUT -vf trim=duration=1
12356 Sharpen or blur the input video.
12358 It accepts the following parameters:
12361 @item luma_msize_x, lx
12362 Set the luma matrix horizontal size. It must be an odd integer between
12363 3 and 63. The default value is 5.
12365 @item luma_msize_y, ly
12366 Set the luma matrix vertical size. It must be an odd integer between 3
12367 and 63. The default value is 5.
12369 @item luma_amount, la
12370 Set the luma effect strength. It must be a floating point number, reasonable
12371 values lay between -1.5 and 1.5.
12373 Negative values will blur the input video, while positive values will
12374 sharpen it, a value of zero will disable the effect.
12376 Default value is 1.0.
12378 @item chroma_msize_x, cx
12379 Set the chroma matrix horizontal size. It must be an odd integer
12380 between 3 and 63. The default value is 5.
12382 @item chroma_msize_y, cy
12383 Set the chroma matrix vertical size. It must be an odd integer
12384 between 3 and 63. The default value is 5.
12386 @item chroma_amount, ca
12387 Set the chroma effect strength. It must be a floating point number, reasonable
12388 values lay between -1.5 and 1.5.
12390 Negative values will blur the input video, while positive values will
12391 sharpen it, a value of zero will disable the effect.
12393 Default value is 0.0.
12396 If set to 1, specify using OpenCL capabilities, only available if
12397 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
12401 All parameters are optional and default to the equivalent of the
12402 string '5:5:1.0:5:5:0.0'.
12404 @subsection Examples
12408 Apply strong luma sharpen effect:
12410 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
12414 Apply a strong blur of both luma and chroma parameters:
12416 unsharp=7:7:-2:7:7:-2
12422 Apply ultra slow/simple postprocessing filter that compresses and decompresses
12423 the image at several (or - in the case of @option{quality} level @code{8} - all)
12424 shifts and average the results.
12426 The way this differs from the behavior of spp is that uspp actually encodes &
12427 decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
12428 DCT similar to MJPEG.
12430 The filter accepts the following options:
12434 Set quality. This option defines the number of levels for averaging. It accepts
12435 an integer in the range 0-8. If set to @code{0}, the filter will have no
12436 effect. A value of @code{8} means the higher quality. For each increment of
12437 that value the speed drops by a factor of approximately 2. Default value is
12441 Force a constant quantization parameter. If not set, the filter will use the QP
12442 from the video stream (if available).
12445 @section vectorscope
12447 Display 2 color component values in the two dimensional graph (which is called
12450 This filter accepts the following options:
12454 Set vectorscope mode.
12456 It accepts the following values:
12459 Gray values are displayed on graph, higher brightness means more pixels have
12460 same component color value on location in graph. This is the default mode.
12463 Gray values are displayed on graph. Surrounding pixels values which are not
12464 present in video frame are drawn in gradient of 2 color components which are
12465 set by option @code{x} and @code{y}.
12468 Actual color components values present in video frame are displayed on graph.
12471 Similar as color2 but higher frequency of same values @code{x} and @code{y}
12472 on graph increases value of another color component, which is luminance by
12473 default values of @code{x} and @code{y}.
12476 Actual colors present in video frame are displayed on graph. If two different
12477 colors map to same position on graph then color with higher value of component
12478 not present in graph is picked.
12482 Set which color component will be represented on X-axis. Default is @code{1}.
12485 Set which color component will be represented on Y-axis. Default is @code{2}.
12488 Set intensity, used by modes: gray, color and color3 for increasing brightness
12489 of color component which represents frequency of (X, Y) location in graph.
12494 No envelope, this is default.
12497 Instant envelope, even darkest single pixel will be clearly highlighted.
12500 Hold maximum and minimum values presented in graph over time. This way you
12501 can still spot out of range values without constantly looking at vectorscope.
12504 Peak and instant envelope combined together.
12508 @anchor{vidstabdetect}
12509 @section vidstabdetect
12511 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
12512 @ref{vidstabtransform} for pass 2.
12514 This filter generates a file with relative translation and rotation
12515 transform information about subsequent frames, which is then used by
12516 the @ref{vidstabtransform} filter.
12518 To enable compilation of this filter you need to configure FFmpeg with
12519 @code{--enable-libvidstab}.
12521 This filter accepts the following options:
12525 Set the path to the file used to write the transforms information.
12526 Default value is @file{transforms.trf}.
12529 Set how shaky the video is and how quick the camera is. It accepts an
12530 integer in the range 1-10, a value of 1 means little shakiness, a
12531 value of 10 means strong shakiness. Default value is 5.
12534 Set the accuracy of the detection process. It must be a value in the
12535 range 1-15. A value of 1 means low accuracy, a value of 15 means high
12536 accuracy. Default value is 15.
12539 Set stepsize of the search process. The region around minimum is
12540 scanned with 1 pixel resolution. Default value is 6.
12543 Set minimum contrast. Below this value a local measurement field is
12544 discarded. Must be a floating point value in the range 0-1. Default
12548 Set reference frame number for tripod mode.
12550 If enabled, the motion of the frames is compared to a reference frame
12551 in the filtered stream, identified by the specified number. The idea
12552 is to compensate all movements in a more-or-less static scene and keep
12553 the camera view absolutely still.
12555 If set to 0, it is disabled. The frames are counted starting from 1.
12558 Show fields and transforms in the resulting frames. It accepts an
12559 integer in the range 0-2. Default value is 0, which disables any
12563 @subsection Examples
12567 Use default values:
12573 Analyze strongly shaky movie and put the results in file
12574 @file{mytransforms.trf}:
12576 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
12580 Visualize the result of internal transformations in the resulting
12583 vidstabdetect=show=1
12587 Analyze a video with medium shakiness using @command{ffmpeg}:
12589 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
12593 @anchor{vidstabtransform}
12594 @section vidstabtransform
12596 Video stabilization/deshaking: pass 2 of 2,
12597 see @ref{vidstabdetect} for pass 1.
12599 Read a file with transform information for each frame and
12600 apply/compensate them. Together with the @ref{vidstabdetect}
12601 filter this can be used to deshake videos. See also
12602 @url{http://public.hronopik.de/vid.stab}. It is important to also use
12603 the @ref{unsharp} filter, see below.
12605 To enable compilation of this filter you need to configure FFmpeg with
12606 @code{--enable-libvidstab}.
12608 @subsection Options
12612 Set path to the file used to read the transforms. Default value is
12613 @file{transforms.trf}.
12616 Set the number of frames (value*2 + 1) used for lowpass filtering the
12617 camera movements. Default value is 10.
12619 For example a number of 10 means that 21 frames are used (10 in the
12620 past and 10 in the future) to smoothen the motion in the video. A
12621 larger value leads to a smoother video, but limits the acceleration of
12622 the camera (pan/tilt movements). 0 is a special case where a static
12623 camera is simulated.
12626 Set the camera path optimization algorithm.
12628 Accepted values are:
12631 gaussian kernel low-pass filter on camera motion (default)
12633 averaging on transformations
12637 Set maximal number of pixels to translate frames. Default value is -1,
12641 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
12642 value is -1, meaning no limit.
12645 Specify how to deal with borders that may be visible due to movement
12648 Available values are:
12651 keep image information from previous frame (default)
12653 fill the border black
12657 Invert transforms if set to 1. Default value is 0.
12660 Consider transforms as relative to previous frame if set to 1,
12661 absolute if set to 0. Default value is 0.
12664 Set percentage to zoom. A positive value will result in a zoom-in
12665 effect, a negative value in a zoom-out effect. Default value is 0 (no
12669 Set optimal zooming to avoid borders.
12671 Accepted values are:
12676 optimal static zoom value is determined (only very strong movements
12677 will lead to visible borders) (default)
12679 optimal adaptive zoom value is determined (no borders will be
12680 visible), see @option{zoomspeed}
12683 Note that the value given at zoom is added to the one calculated here.
12686 Set percent to zoom maximally each frame (enabled when
12687 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
12691 Specify type of interpolation.
12693 Available values are:
12698 linear only horizontal
12700 linear in both directions (default)
12702 cubic in both directions (slow)
12706 Enable virtual tripod mode if set to 1, which is equivalent to
12707 @code{relative=0:smoothing=0}. Default value is 0.
12709 Use also @code{tripod} option of @ref{vidstabdetect}.
12712 Increase log verbosity if set to 1. Also the detected global motions
12713 are written to the temporary file @file{global_motions.trf}. Default
12717 @subsection Examples
12721 Use @command{ffmpeg} for a typical stabilization with default values:
12723 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
12726 Note the use of the @ref{unsharp} filter which is always recommended.
12729 Zoom in a bit more and load transform data from a given file:
12731 vidstabtransform=zoom=5:input="mytransforms.trf"
12735 Smoothen the video even more:
12737 vidstabtransform=smoothing=30
12743 Flip the input video vertically.
12745 For example, to vertically flip a video with @command{ffmpeg}:
12747 ffmpeg -i in.avi -vf "vflip" out.avi
12753 Make or reverse a natural vignetting effect.
12755 The filter accepts the following options:
12759 Set lens angle expression as a number of radians.
12761 The value is clipped in the @code{[0,PI/2]} range.
12763 Default value: @code{"PI/5"}
12767 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
12771 Set forward/backward mode.
12773 Available modes are:
12776 The larger the distance from the central point, the darker the image becomes.
12779 The larger the distance from the central point, the brighter the image becomes.
12780 This can be used to reverse a vignette effect, though there is no automatic
12781 detection to extract the lens @option{angle} and other settings (yet). It can
12782 also be used to create a burning effect.
12785 Default value is @samp{forward}.
12788 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
12790 It accepts the following values:
12793 Evaluate expressions only once during the filter initialization.
12796 Evaluate expressions for each incoming frame. This is way slower than the
12797 @samp{init} mode since it requires all the scalers to be re-computed, but it
12798 allows advanced dynamic expressions.
12801 Default value is @samp{init}.
12804 Set dithering to reduce the circular banding effects. Default is @code{1}
12808 Set vignette aspect. This setting allows one to adjust the shape of the vignette.
12809 Setting this value to the SAR of the input will make a rectangular vignetting
12810 following the dimensions of the video.
12812 Default is @code{1/1}.
12815 @subsection Expressions
12817 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
12818 following parameters.
12823 input width and height
12826 the number of input frame, starting from 0
12829 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
12830 @var{TB} units, NAN if undefined
12833 frame rate of the input video, NAN if the input frame rate is unknown
12836 the PTS (Presentation TimeStamp) of the filtered video frame,
12837 expressed in seconds, NAN if undefined
12840 time base of the input video
12844 @subsection Examples
12848 Apply simple strong vignetting effect:
12854 Make a flickering vignetting:
12856 vignette='PI/4+random(1)*PI/50':eval=frame
12862 Stack input videos vertically.
12864 All streams must be of same pixel format and of same width.
12866 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
12867 to create same output.
12869 The filter accept the following option:
12873 Set number of input streams. Default is 2.
12876 If set to 1, force the output to terminate when the shortest input
12877 terminates. Default value is 0.
12882 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
12883 Deinterlacing Filter").
12885 Based on the process described by Martin Weston for BBC R&D, and
12886 implemented based on the de-interlace algorithm written by Jim
12887 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
12888 uses filter coefficients calculated by BBC R&D.
12890 There are two sets of filter coefficients, so called "simple":
12891 and "complex". Which set of filter coefficients is used can
12892 be set by passing an optional parameter:
12896 Set the interlacing filter coefficients. Accepts one of the following values:
12900 Simple filter coefficient set.
12902 More-complex filter coefficient set.
12904 Default value is @samp{complex}.
12907 Specify which frames to deinterlace. Accept one of the following values:
12911 Deinterlace all frames,
12913 Only deinterlace frames marked as interlaced.
12916 Default value is @samp{all}.
12920 Video waveform monitor.
12922 The waveform monitor plots color component intensity. By default luminance
12923 only. Each column of the waveform corresponds to a column of pixels in the
12926 It accepts the following options:
12930 Can be either @code{row}, or @code{column}. Default is @code{column}.
12931 In row mode, the graph on the left side represents color component value 0 and
12932 the right side represents value = 255. In column mode, the top side represents
12933 color component value = 0 and bottom side represents value = 255.
12936 Set intensity. Smaller values are useful to find out how many values of the same
12937 luminance are distributed across input rows/columns.
12938 Default value is @code{0.04}. Allowed range is [0, 1].
12941 Set mirroring mode. @code{0} means unmirrored, @code{1} means mirrored.
12942 In mirrored mode, higher values will be represented on the left
12943 side for @code{row} mode and at the top for @code{column} mode. Default is
12944 @code{1} (mirrored).
12948 It accepts the following values:
12951 Presents information identical to that in the @code{parade}, except
12952 that the graphs representing color components are superimposed directly
12955 This display mode makes it easier to spot relative differences or similarities
12956 in overlapping areas of the color components that are supposed to be identical,
12957 such as neutral whites, grays, or blacks.
12960 Display separate graph for the color components side by side in
12961 @code{row} mode or one below the other in @code{column} mode.
12963 Using this display mode makes it easy to spot color casts in the highlights
12964 and shadows of an image, by comparing the contours of the top and the bottom
12965 graphs of each waveform. Since whites, grays, and blacks are characterized
12966 by exactly equal amounts of red, green, and blue, neutral areas of the picture
12967 should display three waveforms of roughly equal width/height. If not, the
12968 correction is easy to perform by making level adjustments the three waveforms.
12970 Default is @code{parade}.
12972 @item components, c
12973 Set which color components to display. Default is 1, which means only luminance
12974 or red color component if input is in RGB colorspace. If is set for example to
12975 7 it will display all 3 (if) available color components.
12980 No envelope, this is default.
12983 Instant envelope, minimum and maximum values presented in graph will be easily
12984 visible even with small @code{step} value.
12987 Hold minimum and maximum values presented in graph across time. This way you
12988 can still spot out of range values without constantly looking at waveforms.
12991 Peak and instant envelope combined together.
12997 No filtering, this is default.
13000 Luma and chroma combined together.
13003 Similar as above, but shows difference between blue and red chroma.
13006 Displays only chroma.
13009 Similar as above, but shows difference between blue and red chroma.
13012 Displays actual color value on waveform.
13017 Apply the xBR high-quality magnification filter which is designed for pixel
13018 art. It follows a set of edge-detection rules, see
13019 @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}.
13021 It accepts the following option:
13025 Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
13026 @code{3xBR} and @code{4} for @code{4xBR}.
13027 Default is @code{3}.
13033 Deinterlace the input video ("yadif" means "yet another deinterlacing
13036 It accepts the following parameters:
13042 The interlacing mode to adopt. It accepts one of the following values:
13045 @item 0, send_frame
13046 Output one frame for each frame.
13047 @item 1, send_field
13048 Output one frame for each field.
13049 @item 2, send_frame_nospatial
13050 Like @code{send_frame}, but it skips the spatial interlacing check.
13051 @item 3, send_field_nospatial
13052 Like @code{send_field}, but it skips the spatial interlacing check.
13055 The default value is @code{send_frame}.
13058 The picture field parity assumed for the input interlaced video. It accepts one
13059 of the following values:
13063 Assume the top field is first.
13065 Assume the bottom field is first.
13067 Enable automatic detection of field parity.
13070 The default value is @code{auto}.
13071 If the interlacing is unknown or the decoder does not export this information,
13072 top field first will be assumed.
13075 Specify which frames to deinterlace. Accept one of the following
13080 Deinterlace all frames.
13081 @item 1, interlaced
13082 Only deinterlace frames marked as interlaced.
13085 The default value is @code{all}.
13090 Apply Zoom & Pan effect.
13092 This filter accepts the following options:
13096 Set the zoom expression. Default is 1.
13100 Set the x and y expression. Default is 0.
13103 Set the duration expression in number of frames.
13104 This sets for how many number of frames effect will last for
13105 single input image.
13108 Set the output image size, default is 'hd720'.
13111 Set the output frame rate, default is '25'.
13114 Each expression can contain the following constants:
13133 Output frame count.
13137 Last calculated 'x' and 'y' position from 'x' and 'y' expression
13138 for current input frame.
13142 'x' and 'y' of last output frame of previous input frame or 0 when there was
13143 not yet such frame (first input frame).
13146 Last calculated zoom from 'z' expression for current input frame.
13149 Last calculated zoom of last output frame of previous input frame.
13152 Number of output frames for current input frame. Calculated from 'd' expression
13153 for each input frame.
13156 number of output frames created for previous input frame
13159 Rational number: input width / input height
13162 sample aspect ratio
13165 display aspect ratio
13169 @subsection Examples
13173 Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
13175 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360
13179 Zoom-in up to 1.5 and pan always at center of picture:
13181 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
13186 Scale (resize) the input video, using the z.lib library:
13187 https://github.com/sekrit-twc/zimg.
13189 The zscale filter forces the output display aspect ratio to be the same
13190 as the input, by changing the output sample aspect ratio.
13192 If the input image format is different from the format requested by
13193 the next filter, the zscale filter will convert the input to the
13196 @subsection Options
13197 The filter accepts the following options.
13202 Set the output video dimension expression. Default value is the input
13205 If the @var{width} or @var{w} is 0, the input width is used for the output.
13206 If the @var{height} or @var{h} is 0, the input height is used for the output.
13208 If one of the values is -1, the zscale filter will use a value that
13209 maintains the aspect ratio of the input image, calculated from the
13210 other specified dimension. If both of them are -1, the input size is
13213 If one of the values is -n with n > 1, the zscale filter will also use a value
13214 that maintains the aspect ratio of the input image, calculated from the other
13215 specified dimension. After that it will, however, make sure that the calculated
13216 dimension is divisible by n and adjust the value if necessary.
13218 See below for the list of accepted constants for use in the dimension
13222 Set the video size. For the syntax of this option, check the
13223 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13226 Set the dither type.
13228 Possible values are:
13233 @item error_diffusion
13239 Set the resize filter type.
13241 Possible values are:
13251 Default is bilinear.
13254 Set the color range.
13256 Possible values are:
13263 Default is same as input.
13266 Set the color primaries.
13268 Possible values are:
13278 Default is same as input.
13281 Set the transfer characteristics.
13283 Possible values are:
13294 Default is same as input.
13297 Set the colorspace matrix.
13299 Possible value are:
13310 Default is same as input.
13313 Set the input color range.
13315 Possible values are:
13322 Default is same as input.
13324 @item primariesin, pin
13325 Set the input color primaries.
13327 Possible values are:
13337 Default is same as input.
13339 @item transferin, tin
13340 Set the input transfer characteristics.
13342 Possible values are:
13353 Default is same as input.
13355 @item matrixin, min
13356 Set the input colorspace matrix.
13358 Possible value are:
13370 The values of the @option{w} and @option{h} options are expressions
13371 containing the following constants:
13376 The input width and height
13380 These are the same as @var{in_w} and @var{in_h}.
13384 The output (scaled) width and height
13388 These are the same as @var{out_w} and @var{out_h}
13391 The same as @var{iw} / @var{ih}
13394 input sample aspect ratio
13397 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
13401 horizontal and vertical input chroma subsample values. For example for the
13402 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
13406 horizontal and vertical output chroma subsample values. For example for the
13407 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
13413 @c man end VIDEO FILTERS
13415 @chapter Video Sources
13416 @c man begin VIDEO SOURCES
13418 Below is a description of the currently available video sources.
13422 Buffer video frames, and make them available to the filter chain.
13424 This source is mainly intended for a programmatic use, in particular
13425 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
13427 It accepts the following parameters:
13432 Specify the size (width and height) of the buffered video frames. For the
13433 syntax of this option, check the
13434 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13437 The input video width.
13440 The input video height.
13443 A string representing the pixel format of the buffered video frames.
13444 It may be a number corresponding to a pixel format, or a pixel format
13448 Specify the timebase assumed by the timestamps of the buffered frames.
13451 Specify the frame rate expected for the video stream.
13453 @item pixel_aspect, sar
13454 The sample (pixel) aspect ratio of the input video.
13457 Specify the optional parameters to be used for the scale filter which
13458 is automatically inserted when an input change is detected in the
13459 input size or format.
13461 @item hw_frames_ctx
13462 When using a hardware pixel format, this should be a reference to an
13463 AVHWFramesContext describing input frames.
13468 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
13471 will instruct the source to accept video frames with size 320x240 and
13472 with format "yuv410p", assuming 1/24 as the timestamps timebase and
13473 square pixels (1:1 sample aspect ratio).
13474 Since the pixel format with name "yuv410p" corresponds to the number 6
13475 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
13476 this example corresponds to:
13478 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
13481 Alternatively, the options can be specified as a flat string, but this
13482 syntax is deprecated:
13484 @var{width}:@var{height}:@var{pix_fmt}:@var{time_base.num}:@var{time_base.den}:@var{pixel_aspect.num}:@var{pixel_aspect.den}[:@var{sws_param}]
13488 Create a pattern generated by an elementary cellular automaton.
13490 The initial state of the cellular automaton can be defined through the
13491 @option{filename}, and @option{pattern} options. If such options are
13492 not specified an initial state is created randomly.
13494 At each new frame a new row in the video is filled with the result of
13495 the cellular automaton next generation. The behavior when the whole
13496 frame is filled is defined by the @option{scroll} option.
13498 This source accepts the following options:
13502 Read the initial cellular automaton state, i.e. the starting row, from
13503 the specified file.
13504 In the file, each non-whitespace character is considered an alive
13505 cell, a newline will terminate the row, and further characters in the
13506 file will be ignored.
13509 Read the initial cellular automaton state, i.e. the starting row, from
13510 the specified string.
13512 Each non-whitespace character in the string is considered an alive
13513 cell, a newline will terminate the row, and further characters in the
13514 string will be ignored.
13517 Set the video rate, that is the number of frames generated per second.
13520 @item random_fill_ratio, ratio
13521 Set the random fill ratio for the initial cellular automaton row. It
13522 is a floating point number value ranging from 0 to 1, defaults to
13525 This option is ignored when a file or a pattern is specified.
13527 @item random_seed, seed
13528 Set the seed for filling randomly the initial row, must be an integer
13529 included between 0 and UINT32_MAX. If not specified, or if explicitly
13530 set to -1, the filter will try to use a good random seed on a best
13534 Set the cellular automaton rule, it is a number ranging from 0 to 255.
13535 Default value is 110.
13538 Set the size of the output video. For the syntax of this option, check the
13539 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13541 If @option{filename} or @option{pattern} is specified, the size is set
13542 by default to the width of the specified initial state row, and the
13543 height is set to @var{width} * PHI.
13545 If @option{size} is set, it must contain the width of the specified
13546 pattern string, and the specified pattern will be centered in the
13549 If a filename or a pattern string is not specified, the size value
13550 defaults to "320x518" (used for a randomly generated initial state).
13553 If set to 1, scroll the output upward when all the rows in the output
13554 have been already filled. If set to 0, the new generated row will be
13555 written over the top row just after the bottom row is filled.
13558 @item start_full, full
13559 If set to 1, completely fill the output with generated rows before
13560 outputting the first frame.
13561 This is the default behavior, for disabling set the value to 0.
13564 If set to 1, stitch the left and right row edges together.
13565 This is the default behavior, for disabling set the value to 0.
13568 @subsection Examples
13572 Read the initial state from @file{pattern}, and specify an output of
13575 cellauto=f=pattern:s=200x400
13579 Generate a random initial row with a width of 200 cells, with a fill
13582 cellauto=ratio=2/3:s=200x200
13586 Create a pattern generated by rule 18 starting by a single alive cell
13587 centered on an initial row with width 100:
13589 cellauto=p=@@:s=100x400:full=0:rule=18
13593 Specify a more elaborated initial pattern:
13595 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
13600 @section mandelbrot
13602 Generate a Mandelbrot set fractal, and progressively zoom towards the
13603 point specified with @var{start_x} and @var{start_y}.
13605 This source accepts the following options:
13610 Set the terminal pts value. Default value is 400.
13613 Set the terminal scale value.
13614 Must be a floating point value. Default value is 0.3.
13617 Set the inner coloring mode, that is the algorithm used to draw the
13618 Mandelbrot fractal internal region.
13620 It shall assume one of the following values:
13625 Show time until convergence.
13627 Set color based on point closest to the origin of the iterations.
13632 Default value is @var{mincol}.
13635 Set the bailout value. Default value is 10.0.
13638 Set the maximum of iterations performed by the rendering
13639 algorithm. Default value is 7189.
13642 Set outer coloring mode.
13643 It shall assume one of following values:
13645 @item iteration_count
13646 Set iteration cound mode.
13647 @item normalized_iteration_count
13648 set normalized iteration count mode.
13650 Default value is @var{normalized_iteration_count}.
13653 Set frame rate, expressed as number of frames per second. Default
13657 Set frame size. For the syntax of this option, check the "Video
13658 size" section in the ffmpeg-utils manual. Default value is "640x480".
13661 Set the initial scale value. Default value is 3.0.
13664 Set the initial x position. Must be a floating point value between
13665 -100 and 100. Default value is -0.743643887037158704752191506114774.
13668 Set the initial y position. Must be a floating point value between
13669 -100 and 100. Default value is -0.131825904205311970493132056385139.
13674 Generate various test patterns, as generated by the MPlayer test filter.
13676 The size of the generated video is fixed, and is 256x256.
13677 This source is useful in particular for testing encoding features.
13679 This source accepts the following options:
13684 Specify the frame rate of the sourced video, as the number of frames
13685 generated per second. It has to be a string in the format
13686 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
13687 number or a valid video frame rate abbreviation. The default value is
13691 Set the duration of the sourced video. See
13692 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
13693 for the accepted syntax.
13695 If not specified, or the expressed duration is negative, the video is
13696 supposed to be generated forever.
13700 Set the number or the name of the test to perform. Supported tests are:
13716 Default value is "all", which will cycle through the list of all tests.
13721 mptestsrc=t=dc_luma
13724 will generate a "dc_luma" test pattern.
13726 @section frei0r_src
13728 Provide a frei0r source.
13730 To enable compilation of this filter you need to install the frei0r
13731 header and configure FFmpeg with @code{--enable-frei0r}.
13733 This source accepts the following parameters:
13738 The size of the video to generate. For the syntax of this option, check the
13739 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13742 The framerate of the generated video. It may be a string of the form
13743 @var{num}/@var{den} or a frame rate abbreviation.
13746 The name to the frei0r source to load. For more information regarding frei0r and
13747 how to set the parameters, read the @ref{frei0r} section in the video filters
13750 @item filter_params
13751 A '|'-separated list of parameters to pass to the frei0r source.
13755 For example, to generate a frei0r partik0l source with size 200x200
13756 and frame rate 10 which is overlaid on the overlay filter main input:
13758 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
13763 Generate a life pattern.
13765 This source is based on a generalization of John Conway's life game.
13767 The sourced input represents a life grid, each pixel represents a cell
13768 which can be in one of two possible states, alive or dead. Every cell
13769 interacts with its eight neighbours, which are the cells that are
13770 horizontally, vertically, or diagonally adjacent.
13772 At each interaction the grid evolves according to the adopted rule,
13773 which specifies the number of neighbor alive cells which will make a
13774 cell stay alive or born. The @option{rule} option allows one to specify
13777 This source accepts the following options:
13781 Set the file from which to read the initial grid state. In the file,
13782 each non-whitespace character is considered an alive cell, and newline
13783 is used to delimit the end of each row.
13785 If this option is not specified, the initial grid is generated
13789 Set the video rate, that is the number of frames generated per second.
13792 @item random_fill_ratio, ratio
13793 Set the random fill ratio for the initial random grid. It is a
13794 floating point number value ranging from 0 to 1, defaults to 1/PHI.
13795 It is ignored when a file is specified.
13797 @item random_seed, seed
13798 Set the seed for filling the initial random grid, must be an integer
13799 included between 0 and UINT32_MAX. If not specified, or if explicitly
13800 set to -1, the filter will try to use a good random seed on a best
13806 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
13807 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
13808 @var{NS} specifies the number of alive neighbor cells which make a
13809 live cell stay alive, and @var{NB} the number of alive neighbor cells
13810 which make a dead cell to become alive (i.e. to "born").
13811 "s" and "b" can be used in place of "S" and "B", respectively.
13813 Alternatively a rule can be specified by an 18-bits integer. The 9
13814 high order bits are used to encode the next cell state if it is alive
13815 for each number of neighbor alive cells, the low order bits specify
13816 the rule for "borning" new cells. Higher order bits encode for an
13817 higher number of neighbor cells.
13818 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
13819 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
13821 Default value is "S23/B3", which is the original Conway's game of life
13822 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
13823 cells, and will born a new cell if there are three alive cells around
13827 Set the size of the output video. For the syntax of this option, check the
13828 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13830 If @option{filename} is specified, the size is set by default to the
13831 same size of the input file. If @option{size} is set, it must contain
13832 the size specified in the input file, and the initial grid defined in
13833 that file is centered in the larger resulting area.
13835 If a filename is not specified, the size value defaults to "320x240"
13836 (used for a randomly generated initial grid).
13839 If set to 1, stitch the left and right grid edges together, and the
13840 top and bottom edges also. Defaults to 1.
13843 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
13844 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
13845 value from 0 to 255.
13848 Set the color of living (or new born) cells.
13851 Set the color of dead cells. If @option{mold} is set, this is the first color
13852 used to represent a dead cell.
13855 Set mold color, for definitely dead and moldy cells.
13857 For the syntax of these 3 color options, check the "Color" section in the
13858 ffmpeg-utils manual.
13861 @subsection Examples
13865 Read a grid from @file{pattern}, and center it on a grid of size
13868 life=f=pattern:s=300x300
13872 Generate a random grid of size 200x200, with a fill ratio of 2/3:
13874 life=ratio=2/3:s=200x200
13878 Specify a custom rule for evolving a randomly generated grid:
13884 Full example with slow death effect (mold) using @command{ffplay}:
13886 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
13893 @anchor{haldclutsrc}
13895 @anchor{rgbtestsrc}
13897 @anchor{smptehdbars}
13899 @section allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
13901 The @code{allrgb} source returns frames of size 4096x4096 of all rgb colors.
13903 The @code{allyuv} source returns frames of size 4096x4096 of all yuv colors.
13905 The @code{color} source provides an uniformly colored input.
13907 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
13908 @ref{haldclut} filter.
13910 The @code{nullsrc} source returns unprocessed video frames. It is
13911 mainly useful to be employed in analysis / debugging tools, or as the
13912 source for filters which ignore the input data.
13914 The @code{rgbtestsrc} source generates an RGB test pattern useful for
13915 detecting RGB vs BGR issues. You should see a red, green and blue
13916 stripe from top to bottom.
13918 The @code{smptebars} source generates a color bars pattern, based on
13919 the SMPTE Engineering Guideline EG 1-1990.
13921 The @code{smptehdbars} source generates a color bars pattern, based on
13922 the SMPTE RP 219-2002.
13924 The @code{testsrc} source generates a test video pattern, showing a
13925 color pattern, a scrolling gradient and a timestamp. This is mainly
13926 intended for testing purposes.
13928 The sources accept the following parameters:
13933 Specify the color of the source, only available in the @code{color}
13934 source. For the syntax of this option, check the "Color" section in the
13935 ffmpeg-utils manual.
13938 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
13939 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
13940 pixels to be used as identity matrix for 3D lookup tables. Each component is
13941 coded on a @code{1/(N*N)} scale.
13944 Specify the size of the sourced video. For the syntax of this option, check the
13945 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13946 The default value is @code{320x240}.
13948 This option is not available with the @code{haldclutsrc} filter.
13951 Specify the frame rate of the sourced video, as the number of frames
13952 generated per second. It has to be a string in the format
13953 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
13954 number or a valid video frame rate abbreviation. The default value is
13958 Set the sample aspect ratio of the sourced video.
13961 Set the duration of the sourced video. See
13962 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
13963 for the accepted syntax.
13965 If not specified, or the expressed duration is negative, the video is
13966 supposed to be generated forever.
13969 Set the number of decimals to show in the timestamp, only available in the
13970 @code{testsrc} source.
13972 The displayed timestamp value will correspond to the original
13973 timestamp value multiplied by the power of 10 of the specified
13974 value. Default value is 0.
13977 For example the following:
13979 testsrc=duration=5.3:size=qcif:rate=10
13982 will generate a video with a duration of 5.3 seconds, with size
13983 176x144 and a frame rate of 10 frames per second.
13985 The following graph description will generate a red source
13986 with an opacity of 0.2, with size "qcif" and a frame rate of 10
13989 color=c=red@@0.2:s=qcif:r=10
13992 If the input content is to be ignored, @code{nullsrc} can be used. The
13993 following command generates noise in the luminance plane by employing
13994 the @code{geq} filter:
13996 nullsrc=s=256x256, geq=random(1)*255:128:128
13999 @subsection Commands
14001 The @code{color} source supports the following commands:
14005 Set the color of the created image. Accepts the same syntax of the
14006 corresponding @option{color} option.
14009 @c man end VIDEO SOURCES
14011 @chapter Video Sinks
14012 @c man begin VIDEO SINKS
14014 Below is a description of the currently available video sinks.
14016 @section buffersink
14018 Buffer video frames, and make them available to the end of the filter
14021 This sink is mainly intended for programmatic use, in particular
14022 through the interface defined in @file{libavfilter/buffersink.h}
14023 or the options system.
14025 It accepts a pointer to an AVBufferSinkContext structure, which
14026 defines the incoming buffers' formats, to be passed as the opaque
14027 parameter to @code{avfilter_init_filter} for initialization.
14031 Null video sink: do absolutely nothing with the input video. It is
14032 mainly useful as a template and for use in analysis / debugging
14035 @c man end VIDEO SINKS
14037 @chapter Multimedia Filters
14038 @c man begin MULTIMEDIA FILTERS
14040 Below is a description of the currently available multimedia filters.
14042 @section ahistogram
14044 Convert input audio to a video output, displaying the volume histogram.
14046 The filter accepts the following options:
14050 Specify how histogram is calculated.
14052 It accepts the following values:
14055 Use single histogram for all channels.
14057 Use separate histogram for each channel.
14059 Default is @code{single}.
14062 Set frame rate, expressed as number of frames per second. Default
14066 Specify the video size for the output. For the syntax of this option, check the
14067 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14068 Default value is @code{hd720}.
14073 It accepts the following values:
14084 reverse logarithmic
14086 Default is @code{log}.
14089 Set amplitude scale.
14091 It accepts the following values:
14098 Default is @code{log}.
14101 Set how much frames to accumulate in histogram.
14102 Defauls is 1. Setting this to -1 accumulates all frames.
14105 Set histogram ratio of window height.
14108 Set sonogram sliding.
14110 It accepts the following values:
14113 replace old rows with new ones.
14115 scroll from top to bottom.
14117 Default is @code{replace}.
14120 @section aphasemeter
14122 Convert input audio to a video output, displaying the audio phase.
14124 The filter accepts the following options:
14128 Set the output frame rate. Default value is @code{25}.
14131 Set the video size for the output. For the syntax of this option, check the
14132 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14133 Default value is @code{800x400}.
14138 Specify the red, green, blue contrast. Default values are @code{2},
14139 @code{7} and @code{1}.
14140 Allowed range is @code{[0, 255]}.
14143 Set color which will be used for drawing median phase. If color is
14144 @code{none} which is default, no median phase value will be drawn.
14147 The filter also exports the frame metadata @code{lavfi.aphasemeter.phase} which
14148 represents mean phase of current audio frame. Value is in range @code{[-1, 1]}.
14149 The @code{-1} means left and right channels are completely out of phase and
14150 @code{1} means channels are in phase.
14152 @section avectorscope
14154 Convert input audio to a video output, representing the audio vector
14157 The filter is used to measure the difference between channels of stereo
14158 audio stream. A monoaural signal, consisting of identical left and right
14159 signal, results in straight vertical line. Any stereo separation is visible
14160 as a deviation from this line, creating a Lissajous figure.
14161 If the straight (or deviation from it) but horizontal line appears this
14162 indicates that the left and right channels are out of phase.
14164 The filter accepts the following options:
14168 Set the vectorscope mode.
14170 Available values are:
14173 Lissajous rotated by 45 degrees.
14176 Same as above but not rotated.
14179 Shape resembling half of circle.
14182 Default value is @samp{lissajous}.
14185 Set the video size for the output. For the syntax of this option, check the
14186 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14187 Default value is @code{400x400}.
14190 Set the output frame rate. Default value is @code{25}.
14196 Specify the red, green, blue and alpha contrast. Default values are @code{40},
14197 @code{160}, @code{80} and @code{255}.
14198 Allowed range is @code{[0, 255]}.
14204 Specify the red, green, blue and alpha fade. Default values are @code{15},
14205 @code{10}, @code{5} and @code{5}.
14206 Allowed range is @code{[0, 255]}.
14209 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
14212 Set the vectorscope drawing mode.
14214 Available values are:
14217 Draw dot for each sample.
14220 Draw line between previous and current sample.
14223 Default value is @samp{dot}.
14226 @subsection Examples
14230 Complete example using @command{ffplay}:
14232 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
14233 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
14239 Concatenate audio and video streams, joining them together one after the
14242 The filter works on segments of synchronized video and audio streams. All
14243 segments must have the same number of streams of each type, and that will
14244 also be the number of streams at output.
14246 The filter accepts the following options:
14251 Set the number of segments. Default is 2.
14254 Set the number of output video streams, that is also the number of video
14255 streams in each segment. Default is 1.
14258 Set the number of output audio streams, that is also the number of audio
14259 streams in each segment. Default is 0.
14262 Activate unsafe mode: do not fail if segments have a different format.
14266 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
14267 @var{a} audio outputs.
14269 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
14270 segment, in the same order as the outputs, then the inputs for the second
14273 Related streams do not always have exactly the same duration, for various
14274 reasons including codec frame size or sloppy authoring. For that reason,
14275 related synchronized streams (e.g. a video and its audio track) should be
14276 concatenated at once. The concat filter will use the duration of the longest
14277 stream in each segment (except the last one), and if necessary pad shorter
14278 audio streams with silence.
14280 For this filter to work correctly, all segments must start at timestamp 0.
14282 All corresponding streams must have the same parameters in all segments; the
14283 filtering system will automatically select a common pixel format for video
14284 streams, and a common sample format, sample rate and channel layout for
14285 audio streams, but other settings, such as resolution, must be converted
14286 explicitly by the user.
14288 Different frame rates are acceptable but will result in variable frame rate
14289 at output; be sure to configure the output file to handle it.
14291 @subsection Examples
14295 Concatenate an opening, an episode and an ending, all in bilingual version
14296 (video in stream 0, audio in streams 1 and 2):
14298 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
14299 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
14300 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
14301 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
14305 Concatenate two parts, handling audio and video separately, using the
14306 (a)movie sources, and adjusting the resolution:
14308 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
14309 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
14310 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
14312 Note that a desync will happen at the stitch if the audio and video streams
14313 do not have exactly the same duration in the first file.
14320 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
14321 it unchanged. By default, it logs a message at a frequency of 10Hz with the
14322 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
14323 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
14325 The filter also has a video output (see the @var{video} option) with a real
14326 time graph to observe the loudness evolution. The graphic contains the logged
14327 message mentioned above, so it is not printed anymore when this option is set,
14328 unless the verbose logging is set. The main graphing area contains the
14329 short-term loudness (3 seconds of analysis), and the gauge on the right is for
14330 the momentary loudness (400 milliseconds).
14332 More information about the Loudness Recommendation EBU R128 on
14333 @url{http://tech.ebu.ch/loudness}.
14335 The filter accepts the following options:
14340 Activate the video output. The audio stream is passed unchanged whether this
14341 option is set or no. The video stream will be the first output stream if
14342 activated. Default is @code{0}.
14345 Set the video size. This option is for video only. For the syntax of this
14347 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14348 Default and minimum resolution is @code{640x480}.
14351 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
14352 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
14353 other integer value between this range is allowed.
14356 Set metadata injection. If set to @code{1}, the audio input will be segmented
14357 into 100ms output frames, each of them containing various loudness information
14358 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
14360 Default is @code{0}.
14363 Force the frame logging level.
14365 Available values are:
14368 information logging level
14370 verbose logging level
14373 By default, the logging level is set to @var{info}. If the @option{video} or
14374 the @option{metadata} options are set, it switches to @var{verbose}.
14379 Available modes can be cumulated (the option is a @code{flag} type). Possible
14383 Disable any peak mode (default).
14385 Enable sample-peak mode.
14387 Simple peak mode looking for the higher sample value. It logs a message
14388 for sample-peak (identified by @code{SPK}).
14390 Enable true-peak mode.
14392 If enabled, the peak lookup is done on an over-sampled version of the input
14393 stream for better peak accuracy. It logs a message for true-peak.
14394 (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}).
14395 This mode requires a build with @code{libswresample}.
14399 Treat mono input files as "dual mono". If a mono file is intended for playback
14400 on a stereo system, its EBU R128 measurement will be perceptually incorrect.
14401 If set to @code{true}, this option will compensate for this effect.
14402 Multi-channel input files are not affected by this option.
14405 Set a specific pan law to be used for the measurement of dual mono files.
14406 This parameter is optional, and has a default value of -3.01dB.
14409 @subsection Examples
14413 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
14415 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
14419 Run an analysis with @command{ffmpeg}:
14421 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
14425 @section interleave, ainterleave
14427 Temporally interleave frames from several inputs.
14429 @code{interleave} works with video inputs, @code{ainterleave} with audio.
14431 These filters read frames from several inputs and send the oldest
14432 queued frame to the output.
14434 Input streams must have a well defined, monotonically increasing frame
14437 In order to submit one frame to output, these filters need to enqueue
14438 at least one frame for each input, so they cannot work in case one
14439 input is not yet terminated and will not receive incoming frames.
14441 For example consider the case when one input is a @code{select} filter
14442 which always drop input frames. The @code{interleave} filter will keep
14443 reading from that input, but it will never be able to send new frames
14444 to output until the input will send an end-of-stream signal.
14446 Also, depending on inputs synchronization, the filters will drop
14447 frames in case one input receives more frames than the other ones, and
14448 the queue is already filled.
14450 These filters accept the following options:
14454 Set the number of different inputs, it is 2 by default.
14457 @subsection Examples
14461 Interleave frames belonging to different streams using @command{ffmpeg}:
14463 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
14467 Add flickering blur effect:
14469 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
14473 @section perms, aperms
14475 Set read/write permissions for the output frames.
14477 These filters are mainly aimed at developers to test direct path in the
14478 following filter in the filtergraph.
14480 The filters accept the following options:
14484 Select the permissions mode.
14486 It accepts the following values:
14489 Do nothing. This is the default.
14491 Set all the output frames read-only.
14493 Set all the output frames directly writable.
14495 Make the frame read-only if writable, and writable if read-only.
14497 Set each output frame read-only or writable randomly.
14501 Set the seed for the @var{random} mode, must be an integer included between
14502 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
14503 @code{-1}, the filter will try to use a good random seed on a best effort
14507 Note: in case of auto-inserted filter between the permission filter and the
14508 following one, the permission might not be received as expected in that
14509 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
14510 perms/aperms filter can avoid this problem.
14512 @section realtime, arealtime
14514 Slow down filtering to match real time approximatively.
14516 These filters will pause the filtering for a variable amount of time to
14517 match the output rate with the input timestamps.
14518 They are similar to the @option{re} option to @code{ffmpeg}.
14520 They accept the following options:
14524 Time limit for the pauses. Any pause longer than that will be considered
14525 a timestamp discontinuity and reset the timer. Default is 2 seconds.
14528 @section select, aselect
14530 Select frames to pass in output.
14532 This filter accepts the following options:
14537 Set expression, which is evaluated for each input frame.
14539 If the expression is evaluated to zero, the frame is discarded.
14541 If the evaluation result is negative or NaN, the frame is sent to the
14542 first output; otherwise it is sent to the output with index
14543 @code{ceil(val)-1}, assuming that the input index starts from 0.
14545 For example a value of @code{1.2} corresponds to the output with index
14546 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
14549 Set the number of outputs. The output to which to send the selected
14550 frame is based on the result of the evaluation. Default value is 1.
14553 The expression can contain the following constants:
14557 The (sequential) number of the filtered frame, starting from 0.
14560 The (sequential) number of the selected frame, starting from 0.
14562 @item prev_selected_n
14563 The sequential number of the last selected frame. It's NAN if undefined.
14566 The timebase of the input timestamps.
14569 The PTS (Presentation TimeStamp) of the filtered video frame,
14570 expressed in @var{TB} units. It's NAN if undefined.
14573 The PTS of the filtered video frame,
14574 expressed in seconds. It's NAN if undefined.
14577 The PTS of the previously filtered video frame. It's NAN if undefined.
14579 @item prev_selected_pts
14580 The PTS of the last previously filtered video frame. It's NAN if undefined.
14582 @item prev_selected_t
14583 The PTS of the last previously selected video frame. It's NAN if undefined.
14586 The PTS of the first video frame in the video. It's NAN if undefined.
14589 The time of the first video frame in the video. It's NAN if undefined.
14591 @item pict_type @emph{(video only)}
14592 The type of the filtered frame. It can assume one of the following
14604 @item interlace_type @emph{(video only)}
14605 The frame interlace type. It can assume one of the following values:
14608 The frame is progressive (not interlaced).
14610 The frame is top-field-first.
14612 The frame is bottom-field-first.
14615 @item consumed_sample_n @emph{(audio only)}
14616 the number of selected samples before the current frame
14618 @item samples_n @emph{(audio only)}
14619 the number of samples in the current frame
14621 @item sample_rate @emph{(audio only)}
14622 the input sample rate
14625 This is 1 if the filtered frame is a key-frame, 0 otherwise.
14628 the position in the file of the filtered frame, -1 if the information
14629 is not available (e.g. for synthetic video)
14631 @item scene @emph{(video only)}
14632 value between 0 and 1 to indicate a new scene; a low value reflects a low
14633 probability for the current frame to introduce a new scene, while a higher
14634 value means the current frame is more likely to be one (see the example below)
14636 @item concatdec_select
14637 The concat demuxer can select only part of a concat input file by setting an
14638 inpoint and an outpoint, but the output packets may not be entirely contained
14639 in the selected interval. By using this variable, it is possible to skip frames
14640 generated by the concat demuxer which are not exactly contained in the selected
14643 This works by comparing the frame pts against the @var{lavf.concat.start_time}
14644 and the @var{lavf.concat.duration} packet metadata values which are also
14645 present in the decoded frames.
14647 The @var{concatdec_select} variable is -1 if the frame pts is at least
14648 start_time and either the duration metadata is missing or the frame pts is less
14649 than start_time + duration, 0 otherwise, and NaN if the start_time metadata is
14652 That basically means that an input frame is selected if its pts is within the
14653 interval set by the concat demuxer.
14657 The default value of the select expression is "1".
14659 @subsection Examples
14663 Select all frames in input:
14668 The example above is the same as:
14680 Select only I-frames:
14682 select='eq(pict_type\,I)'
14686 Select one frame every 100:
14688 select='not(mod(n\,100))'
14692 Select only frames contained in the 10-20 time interval:
14694 select=between(t\,10\,20)
14698 Select only I frames contained in the 10-20 time interval:
14700 select=between(t\,10\,20)*eq(pict_type\,I)
14704 Select frames with a minimum distance of 10 seconds:
14706 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
14710 Use aselect to select only audio frames with samples number > 100:
14712 aselect='gt(samples_n\,100)'
14716 Create a mosaic of the first scenes:
14718 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
14721 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
14725 Send even and odd frames to separate outputs, and compose them:
14727 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
14731 Select useful frames from an ffconcat file which is using inpoints and
14732 outpoints but where the source files are not intra frame only.
14734 ffmpeg -copyts -vsync 0 -segment_time_metadata 1 -i input.ffconcat -vf select=concatdec_select -af aselect=concatdec_select output.avi
14738 @section sendcmd, asendcmd
14740 Send commands to filters in the filtergraph.
14742 These filters read commands to be sent to other filters in the
14745 @code{sendcmd} must be inserted between two video filters,
14746 @code{asendcmd} must be inserted between two audio filters, but apart
14747 from that they act the same way.
14749 The specification of commands can be provided in the filter arguments
14750 with the @var{commands} option, or in a file specified by the
14751 @var{filename} option.
14753 These filters accept the following options:
14756 Set the commands to be read and sent to the other filters.
14758 Set the filename of the commands to be read and sent to the other
14762 @subsection Commands syntax
14764 A commands description consists of a sequence of interval
14765 specifications, comprising a list of commands to be executed when a
14766 particular event related to that interval occurs. The occurring event
14767 is typically the current frame time entering or leaving a given time
14770 An interval is specified by the following syntax:
14772 @var{START}[-@var{END}] @var{COMMANDS};
14775 The time interval is specified by the @var{START} and @var{END} times.
14776 @var{END} is optional and defaults to the maximum time.
14778 The current frame time is considered within the specified interval if
14779 it is included in the interval [@var{START}, @var{END}), that is when
14780 the time is greater or equal to @var{START} and is lesser than
14783 @var{COMMANDS} consists of a sequence of one or more command
14784 specifications, separated by ",", relating to that interval. The
14785 syntax of a command specification is given by:
14787 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
14790 @var{FLAGS} is optional and specifies the type of events relating to
14791 the time interval which enable sending the specified command, and must
14792 be a non-null sequence of identifier flags separated by "+" or "|" and
14793 enclosed between "[" and "]".
14795 The following flags are recognized:
14798 The command is sent when the current frame timestamp enters the
14799 specified interval. In other words, the command is sent when the
14800 previous frame timestamp was not in the given interval, and the
14804 The command is sent when the current frame timestamp leaves the
14805 specified interval. In other words, the command is sent when the
14806 previous frame timestamp was in the given interval, and the
14810 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
14813 @var{TARGET} specifies the target of the command, usually the name of
14814 the filter class or a specific filter instance name.
14816 @var{COMMAND} specifies the name of the command for the target filter.
14818 @var{ARG} is optional and specifies the optional list of argument for
14819 the given @var{COMMAND}.
14821 Between one interval specification and another, whitespaces, or
14822 sequences of characters starting with @code{#} until the end of line,
14823 are ignored and can be used to annotate comments.
14825 A simplified BNF description of the commands specification syntax
14828 @var{COMMAND_FLAG} ::= "enter" | "leave"
14829 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
14830 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
14831 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
14832 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
14833 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
14836 @subsection Examples
14840 Specify audio tempo change at second 4:
14842 asendcmd=c='4.0 atempo tempo 1.5',atempo
14846 Specify a list of drawtext and hue commands in a file.
14848 # show text in the interval 5-10
14849 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
14850 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
14852 # desaturate the image in the interval 15-20
14853 15.0-20.0 [enter] hue s 0,
14854 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
14856 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
14858 # apply an exponential saturation fade-out effect, starting from time 25
14859 25 [enter] hue s exp(25-t)
14862 A filtergraph allowing to read and process the above command list
14863 stored in a file @file{test.cmd}, can be specified with:
14865 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
14870 @section setpts, asetpts
14872 Change the PTS (presentation timestamp) of the input frames.
14874 @code{setpts} works on video frames, @code{asetpts} on audio frames.
14876 This filter accepts the following options:
14881 The expression which is evaluated for each frame to construct its timestamp.
14885 The expression is evaluated through the eval API and can contain the following
14890 frame rate, only defined for constant frame-rate video
14893 The presentation timestamp in input
14896 The count of the input frame for video or the number of consumed samples,
14897 not including the current frame for audio, starting from 0.
14899 @item NB_CONSUMED_SAMPLES
14900 The number of consumed samples, not including the current frame (only
14903 @item NB_SAMPLES, S
14904 The number of samples in the current frame (only audio)
14906 @item SAMPLE_RATE, SR
14907 The audio sample rate.
14910 The PTS of the first frame.
14913 the time in seconds of the first frame
14916 State whether the current frame is interlaced.
14919 the time in seconds of the current frame
14922 original position in the file of the frame, or undefined if undefined
14923 for the current frame
14926 The previous input PTS.
14929 previous input time in seconds
14932 The previous output PTS.
14935 previous output time in seconds
14938 The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
14942 The wallclock (RTC) time at the start of the movie in microseconds.
14945 The timebase of the input timestamps.
14949 @subsection Examples
14953 Start counting PTS from zero
14955 setpts=PTS-STARTPTS
14959 Apply fast motion effect:
14965 Apply slow motion effect:
14971 Set fixed rate of 25 frames per second:
14977 Set fixed rate 25 fps with some jitter:
14979 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
14983 Apply an offset of 10 seconds to the input PTS:
14989 Generate timestamps from a "live source" and rebase onto the current timebase:
14991 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
14995 Generate timestamps by counting samples:
15002 @section settb, asettb
15004 Set the timebase to use for the output frames timestamps.
15005 It is mainly useful for testing timebase configuration.
15007 It accepts the following parameters:
15012 The expression which is evaluated into the output timebase.
15016 The value for @option{tb} is an arithmetic expression representing a
15017 rational. The expression can contain the constants "AVTB" (the default
15018 timebase), "intb" (the input timebase) and "sr" (the sample rate,
15019 audio only). Default value is "intb".
15021 @subsection Examples
15025 Set the timebase to 1/25:
15031 Set the timebase to 1/10:
15037 Set the timebase to 1001/1000:
15043 Set the timebase to 2*intb:
15049 Set the default timebase value:
15056 Convert input audio to a video output representing frequency spectrum
15057 logarithmically using Brown-Puckette constant Q transform algorithm with
15058 direct frequency domain coefficient calculation (but the transform itself
15059 is not really constant Q, instead the Q factor is actually variable/clamped),
15060 with musical tone scale, from E0 to D#10.
15062 The filter accepts the following options:
15066 Specify the video size for the output. It must be even. For the syntax of this option,
15067 check the @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15068 Default value is @code{1920x1080}.
15071 Set the output frame rate. Default value is @code{25}.
15074 Set the bargraph height. It must be even. Default value is @code{-1} which
15075 computes the bargraph height automatically.
15078 Set the axis height. It must be even. Default value is @code{-1} which computes
15079 the axis height automatically.
15082 Set the sonogram height. It must be even. Default value is @code{-1} which
15083 computes the sonogram height automatically.
15086 Set the fullhd resolution. This option is deprecated, use @var{size}, @var{s}
15087 instead. Default value is @code{1}.
15089 @item sono_v, volume
15090 Specify the sonogram volume expression. It can contain variables:
15093 the @var{bar_v} evaluated expression
15094 @item frequency, freq, f
15095 the frequency where it is evaluated
15096 @item timeclamp, tc
15097 the value of @var{timeclamp} option
15101 @item a_weighting(f)
15102 A-weighting of equal loudness
15103 @item b_weighting(f)
15104 B-weighting of equal loudness
15105 @item c_weighting(f)
15106 C-weighting of equal loudness.
15108 Default value is @code{16}.
15110 @item bar_v, volume2
15111 Specify the bargraph volume expression. It can contain variables:
15114 the @var{sono_v} evaluated expression
15115 @item frequency, freq, f
15116 the frequency where it is evaluated
15117 @item timeclamp, tc
15118 the value of @var{timeclamp} option
15122 @item a_weighting(f)
15123 A-weighting of equal loudness
15124 @item b_weighting(f)
15125 B-weighting of equal loudness
15126 @item c_weighting(f)
15127 C-weighting of equal loudness.
15129 Default value is @code{sono_v}.
15131 @item sono_g, gamma
15132 Specify the sonogram gamma. Lower gamma makes the spectrum more contrast,
15133 higher gamma makes the spectrum having more range. Default value is @code{3}.
15134 Acceptable range is @code{[1, 7]}.
15136 @item bar_g, gamma2
15137 Specify the bargraph gamma. Default value is @code{1}. Acceptable range is
15140 @item timeclamp, tc
15141 Specify the transform timeclamp. At low frequency, there is trade-off between
15142 accuracy in time domain and frequency domain. If timeclamp is lower,
15143 event in time domain is represented more accurately (such as fast bass drum),
15144 otherwise event in frequency domain is represented more accurately
15145 (such as bass guitar). Acceptable range is @code{[0.1, 1]}. Default value is @code{0.17}.
15148 Specify the transform base frequency. Default value is @code{20.01523126408007475},
15149 which is frequency 50 cents below E0. Acceptable range is @code{[10, 100000]}.
15152 Specify the transform end frequency. Default value is @code{20495.59681441799654},
15153 which is frequency 50 cents above D#10. Acceptable range is @code{[10, 100000]}.
15156 This option is deprecated and ignored.
15159 Specify the transform length in time domain. Use this option to control accuracy
15160 trade-off between time domain and frequency domain at every frequency sample.
15161 It can contain variables:
15163 @item frequency, freq, f
15164 the frequency where it is evaluated
15165 @item timeclamp, tc
15166 the value of @var{timeclamp} option.
15168 Default value is @code{384*tc/(384+tc*f)}.
15171 Specify the transform count for every video frame. Default value is @code{6}.
15172 Acceptable range is @code{[1, 30]}.
15175 Specify the transform count for every single pixel. Default value is @code{0},
15176 which makes it computed automatically. Acceptable range is @code{[0, 10]}.
15179 Specify font file for use with freetype to draw the axis. If not specified,
15180 use embedded font. Note that drawing with font file or embedded font is not
15181 implemented with custom @var{basefreq} and @var{endfreq}, use @var{axisfile}
15185 Specify font color expression. This is arithmetic expression that should return
15186 integer value 0xRRGGBB. It can contain variables:
15188 @item frequency, freq, f
15189 the frequency where it is evaluated
15190 @item timeclamp, tc
15191 the value of @var{timeclamp} option
15196 midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
15197 @item r(x), g(x), b(x)
15198 red, green, and blue value of intensity x.
15200 Default value is @code{st(0, (midi(f)-59.5)/12);
15201 st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
15202 r(1-ld(1)) + b(ld(1))}.
15205 Specify image file to draw the axis. This option override @var{fontfile} and
15206 @var{fontcolor} option.
15209 Enable/disable drawing text to the axis. If it is set to @code{0}, drawing to
15210 the axis is disabled, ignoring @var{fontfile} and @var{axisfile} option.
15211 Default value is @code{1}.
15215 @subsection Examples
15219 Playing audio while showing the spectrum:
15221 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
15225 Same as above, but with frame rate 30 fps:
15227 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
15231 Playing at 1280x720:
15233 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=s=1280x720:count=4 [out0]'
15237 Disable sonogram display:
15243 A1 and its harmonics: A1, A2, (near)E3, A3:
15245 ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
15246 asplit[a][out1]; [a] showcqt [out0]'
15250 Same as above, but with more accuracy in frequency domain:
15252 ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
15253 asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
15259 bar_v=10:sono_v=bar_v*a_weighting(f)
15263 Custom gamma, now spectrum is linear to the amplitude.
15269 Custom tlength equation:
15271 tc=0.33:tlength='st(0,0.17); 384*tc / (384 / ld(0) + tc*f /(1-ld(0))) + 384*tc / (tc*f / ld(0) + 384 /(1-ld(0)))'
15275 Custom fontcolor and fontfile, C-note is colored green, others are colored blue:
15277 fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))':fontfile=myfont.ttf
15281 Custom frequency range with custom axis using image file:
15283 axisfile=myaxis.png:basefreq=40:endfreq=10000
15289 Convert input audio to video output representing the audio power spectrum.
15290 Audio amplitude is on Y-axis while frequency is on X-axis.
15292 The filter accepts the following options:
15296 Specify size of video. For the syntax of this option, check the
15297 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15298 Default is @code{1024x512}.
15302 This set how each frequency bin will be represented.
15304 It accepts the following values:
15310 Default is @code{bar}.
15313 Set amplitude scale.
15315 It accepts the following values:
15329 Default is @code{log}.
15332 Set frequency scale.
15334 It accepts the following values:
15343 Reverse logarithmic scale.
15345 Default is @code{lin}.
15350 It accepts the following values:
15366 Default is @code{w2048}
15369 Set windowing function.
15371 It accepts the following values:
15389 Default is @code{hanning}.
15392 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
15393 which means optimal overlap for selected window function will be picked.
15396 Set time averaging. Setting this to 0 will display current maximal peaks.
15397 Default is @code{1}, which means time averaging is disabled.
15400 Specify list of colors separated by space or by '|' which will be used to
15401 draw channel frequencies. Unrecognized or missing colors will be replaced
15405 Set channel display mode.
15407 It accepts the following values:
15412 Default is @code{combined}.
15416 @anchor{showspectrum}
15417 @section showspectrum
15419 Convert input audio to a video output, representing the audio frequency
15422 The filter accepts the following options:
15426 Specify the video size for the output. For the syntax of this option, check the
15427 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15428 Default value is @code{640x512}.
15431 Specify how the spectrum should slide along the window.
15433 It accepts the following values:
15436 the samples start again on the left when they reach the right
15438 the samples scroll from right to left
15440 the samples scroll from left to right
15442 frames are only produced when the samples reach the right
15445 Default value is @code{replace}.
15448 Specify display mode.
15450 It accepts the following values:
15453 all channels are displayed in the same row
15455 all channels are displayed in separate rows
15458 Default value is @samp{combined}.
15461 Specify display color mode.
15463 It accepts the following values:
15466 each channel is displayed in a separate color
15468 each channel is displayed using the same color scheme
15470 each channel is displayed using the rainbow color scheme
15472 each channel is displayed using the moreland color scheme
15474 each channel is displayed using the nebulae color scheme
15476 each channel is displayed using the fire color scheme
15478 each channel is displayed using the fiery color scheme
15480 each channel is displayed using the fruit color scheme
15482 each channel is displayed using the cool color scheme
15485 Default value is @samp{channel}.
15488 Specify scale used for calculating intensity color values.
15490 It accepts the following values:
15495 square root, default
15506 Default value is @samp{sqrt}.
15509 Set saturation modifier for displayed colors. Negative values provide
15510 alternative color scheme. @code{0} is no saturation at all.
15511 Saturation must be in [-10.0, 10.0] range.
15512 Default value is @code{1}.
15515 Set window function.
15517 It accepts the following values:
15537 Default value is @code{hann}.
15540 Set orientation of time vs frequency axis. Can be @code{vertical} or
15541 @code{horizontal}. Default is @code{vertical}.
15544 Set ratio of overlap window. Default value is @code{0}.
15545 When value is @code{1} overlap is set to recommended size for specific
15546 window function currently used.
15549 Set scale gain for calculating intensity color values.
15550 Default value is @code{1}.
15553 Set which data to display. Can be @code{magnitude}, default or @code{phase}.
15556 The usage is very similar to the showwaves filter; see the examples in that
15559 @subsection Examples
15563 Large window with logarithmic color scaling:
15565 showspectrum=s=1280x480:scale=log
15569 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
15571 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
15572 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
15576 @section showspectrumpic
15578 Convert input audio to a single video frame, representing the audio frequency
15581 The filter accepts the following options:
15585 Specify the video size for the output. For the syntax of this option, check the
15586 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15587 Default value is @code{4096x2048}.
15590 Specify display mode.
15592 It accepts the following values:
15595 all channels are displayed in the same row
15597 all channels are displayed in separate rows
15599 Default value is @samp{combined}.
15602 Specify display color mode.
15604 It accepts the following values:
15607 each channel is displayed in a separate color
15609 each channel is displayed using the same color scheme
15611 each channel is displayed using the rainbow color scheme
15613 each channel is displayed using the moreland color scheme
15615 each channel is displayed using the nebulae color scheme
15617 each channel is displayed using the fire color scheme
15619 each channel is displayed using the fiery color scheme
15621 each channel is displayed using the fruit color scheme
15623 each channel is displayed using the cool color scheme
15625 Default value is @samp{intensity}.
15628 Specify scale used for calculating intensity color values.
15630 It accepts the following values:
15635 square root, default
15645 Default value is @samp{log}.
15648 Set saturation modifier for displayed colors. Negative values provide
15649 alternative color scheme. @code{0} is no saturation at all.
15650 Saturation must be in [-10.0, 10.0] range.
15651 Default value is @code{1}.
15654 Set window function.
15656 It accepts the following values:
15675 Default value is @code{hann}.
15678 Set orientation of time vs frequency axis. Can be @code{vertical} or
15679 @code{horizontal}. Default is @code{vertical}.
15682 Set scale gain for calculating intensity color values.
15683 Default value is @code{1}.
15686 Draw time and frequency axes and legends. Default is enabled.
15689 @subsection Examples
15693 Extract an audio spectrogram of a whole audio track
15694 in a 1024x1024 picture using @command{ffmpeg}:
15696 ffmpeg -i audio.flac -lavfi showspectrumpic=s=1024x1024 spectrogram.png
15700 @section showvolume
15702 Convert input audio volume to a video output.
15704 The filter accepts the following options:
15711 Set border width, allowed range is [0, 5]. Default is 1.
15714 Set channel width, allowed range is [80, 1080]. Default is 400.
15717 Set channel height, allowed range is [1, 100]. Default is 20.
15720 Set fade, allowed range is [0.001, 1]. Default is 0.95.
15723 Set volume color expression.
15725 The expression can use the following variables:
15729 Current max volume of channel in dB.
15732 Current channel number, starting from 0.
15736 If set, displays channel names. Default is enabled.
15739 If set, displays volume values. Default is enabled.
15744 Convert input audio to a video output, representing the samples waves.
15746 The filter accepts the following options:
15750 Specify the video size for the output. For the syntax of this option, check the
15751 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15752 Default value is @code{600x240}.
15757 Available values are:
15760 Draw a point for each sample.
15763 Draw a vertical line for each sample.
15766 Draw a point for each sample and a line between them.
15769 Draw a centered vertical line for each sample.
15772 Default value is @code{point}.
15775 Set the number of samples which are printed on the same column. A
15776 larger value will decrease the frame rate. Must be a positive
15777 integer. This option can be set only if the value for @var{rate}
15778 is not explicitly specified.
15781 Set the (approximate) output frame rate. This is done by setting the
15782 option @var{n}. Default value is "25".
15784 @item split_channels
15785 Set if channels should be drawn separately or overlap. Default value is 0.
15788 Set colors separated by '|' which are going to be used for drawing of each channel.
15791 Set amplitude scale. Can be linear @code{lin} or logarithmic @code{log}.
15796 @subsection Examples
15800 Output the input file audio and the corresponding video representation
15803 amovie=a.mp3,asplit[out0],showwaves[out1]
15807 Create a synthetic signal and show it with showwaves, forcing a
15808 frame rate of 30 frames per second:
15810 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
15814 @section showwavespic
15816 Convert input audio to a single video frame, representing the samples waves.
15818 The filter accepts the following options:
15822 Specify the video size for the output. For the syntax of this option, check the
15823 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15824 Default value is @code{600x240}.
15826 @item split_channels
15827 Set if channels should be drawn separately or overlap. Default value is 0.
15830 Set colors separated by '|' which are going to be used for drawing of each channel.
15833 Set amplitude scale. Can be linear @code{lin} or logarithmic @code{log}.
15837 @subsection Examples
15841 Extract a channel split representation of the wave form of a whole audio track
15842 in a 1024x800 picture using @command{ffmpeg}:
15844 ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
15848 Colorize the waveform with colorchannelmixer. This example will make
15849 the waveform a green color approximately RGB(66,217,150). Additional
15850 channels will be shades of this color.
15852 ffmpeg -i audio.mp3 -filter_complex "showwavespic,colorchannelmixer=rr=66/255:gg=217/255:bb=150/255" waveform.png
15856 @section spectrumsynth
15858 Sythesize audio from 2 input video spectrums, first input stream represents
15859 magnitude across time and second represents phase across time.
15860 The filter will transform from frequency domain as displayed in videos back
15861 to time domain as presented in audio output.
15863 This filter is primarly created for reversing processed @ref{showspectrum}
15864 filter outputs, but can synthesize sound from other spectrograms too.
15865 But in such case results are going to be poor if the phase data is not
15866 available, because in such cases phase data need to be recreated, usually
15867 its just recreated from random noise.
15868 For best results use gray only output (@code{channel} color mode in
15869 @ref{showspectrum} filter) and @code{log} scale for magnitude video and
15870 @code{lin} scale for phase video. To produce phase, for 2nd video, use
15871 @code{data} option. Inputs videos should generally use @code{fullframe}
15872 slide mode as that saves resources needed for decoding video.
15874 The filter accepts the following options:
15878 Specify sample rate of output audio, the sample rate of audio from which
15879 spectrum was generated may differ.
15882 Set number of channels represented in input video spectrums.
15885 Set scale which was used when generating magnitude input spectrum.
15886 Can be @code{lin} or @code{log}. Default is @code{log}.
15889 Set slide which was used when generating inputs spectrums.
15890 Can be @code{replace}, @code{scroll}, @code{fullframe} or @code{rscroll}.
15891 Default is @code{fullframe}.
15894 Set window function used for resynthesis.
15897 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
15898 which means optimal overlap for selected window function will be picked.
15901 Set orientation of input videos. Can be @code{vertical} or @code{horizontal}.
15902 Default is @code{vertical}.
15905 @subsection Examples
15909 First create magnitude and phase videos from audio, assuming audio is stereo with 44100 sample rate,
15910 then resynthesize videos back to audio with spectrumsynth:
15912 ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=log:overlap=0.875:color=channel:slide=fullframe:data=magnitude -an -c:v rawvideo magnitude.nut
15913 ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=lin:overlap=0.875:color=channel:slide=fullframe:data=phase -an -c:v rawvideo phase.nut
15914 ffmpeg -i magnitude.nut -i phase.nut -lavfi spectrumsynth=channels=2:sample_rate=44100:win_func=hann:overlap=0.875:slide=fullframe output.flac
15918 @section split, asplit
15920 Split input into several identical outputs.
15922 @code{asplit} works with audio input, @code{split} with video.
15924 The filter accepts a single parameter which specifies the number of outputs. If
15925 unspecified, it defaults to 2.
15927 @subsection Examples
15931 Create two separate outputs from the same input:
15933 [in] split [out0][out1]
15937 To create 3 or more outputs, you need to specify the number of
15940 [in] asplit=3 [out0][out1][out2]
15944 Create two separate outputs from the same input, one cropped and
15947 [in] split [splitout1][splitout2];
15948 [splitout1] crop=100:100:0:0 [cropout];
15949 [splitout2] pad=200:200:100:100 [padout];
15953 Create 5 copies of the input audio with @command{ffmpeg}:
15955 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
15961 Receive commands sent through a libzmq client, and forward them to
15962 filters in the filtergraph.
15964 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
15965 must be inserted between two video filters, @code{azmq} between two
15968 To enable these filters you need to install the libzmq library and
15969 headers and configure FFmpeg with @code{--enable-libzmq}.
15971 For more information about libzmq see:
15972 @url{http://www.zeromq.org/}
15974 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
15975 receives messages sent through a network interface defined by the
15976 @option{bind_address} option.
15978 The received message must be in the form:
15980 @var{TARGET} @var{COMMAND} [@var{ARG}]
15983 @var{TARGET} specifies the target of the command, usually the name of
15984 the filter class or a specific filter instance name.
15986 @var{COMMAND} specifies the name of the command for the target filter.
15988 @var{ARG} is optional and specifies the optional argument list for the
15989 given @var{COMMAND}.
15991 Upon reception, the message is processed and the corresponding command
15992 is injected into the filtergraph. Depending on the result, the filter
15993 will send a reply to the client, adopting the format:
15995 @var{ERROR_CODE} @var{ERROR_REASON}
15999 @var{MESSAGE} is optional.
16001 @subsection Examples
16003 Look at @file{tools/zmqsend} for an example of a zmq client which can
16004 be used to send commands processed by these filters.
16006 Consider the following filtergraph generated by @command{ffplay}
16008 ffplay -dumpgraph 1 -f lavfi "
16009 color=s=100x100:c=red [l];
16010 color=s=100x100:c=blue [r];
16011 nullsrc=s=200x100, zmq [bg];
16012 [bg][l] overlay [bg+l];
16013 [bg+l][r] overlay=x=100 "
16016 To change the color of the left side of the video, the following
16017 command can be used:
16019 echo Parsed_color_0 c yellow | tools/zmqsend
16022 To change the right side:
16024 echo Parsed_color_1 c pink | tools/zmqsend
16027 @c man end MULTIMEDIA FILTERS
16029 @chapter Multimedia Sources
16030 @c man begin MULTIMEDIA SOURCES
16032 Below is a description of the currently available multimedia sources.
16036 This is the same as @ref{movie} source, except it selects an audio
16042 Read audio and/or video stream(s) from a movie container.
16044 It accepts the following parameters:
16048 The name of the resource to read (not necessarily a file; it can also be a
16049 device or a stream accessed through some protocol).
16051 @item format_name, f
16052 Specifies the format assumed for the movie to read, and can be either
16053 the name of a container or an input device. If not specified, the
16054 format is guessed from @var{movie_name} or by probing.
16056 @item seek_point, sp
16057 Specifies the seek point in seconds. The frames will be output
16058 starting from this seek point. The parameter is evaluated with
16059 @code{av_strtod}, so the numerical value may be suffixed by an IS
16060 postfix. The default value is "0".
16063 Specifies the streams to read. Several streams can be specified,
16064 separated by "+". The source will then have as many outputs, in the
16065 same order. The syntax is explained in the ``Stream specifiers''
16066 section in the ffmpeg manual. Two special names, "dv" and "da" specify
16067 respectively the default (best suited) video and audio stream. Default
16068 is "dv", or "da" if the filter is called as "amovie".
16070 @item stream_index, si
16071 Specifies the index of the video stream to read. If the value is -1,
16072 the most suitable video stream will be automatically selected. The default
16073 value is "-1". Deprecated. If the filter is called "amovie", it will select
16074 audio instead of video.
16077 Specifies how many times to read the stream in sequence.
16078 If the value is less than 1, the stream will be read again and again.
16079 Default value is "1".
16081 Note that when the movie is looped the source timestamps are not
16082 changed, so it will generate non monotonically increasing timestamps.
16085 It allows overlaying a second video on top of the main input of
16086 a filtergraph, as shown in this graph:
16088 input -----------> deltapts0 --> overlay --> output
16091 movie --> scale--> deltapts1 -------+
16093 @subsection Examples
16097 Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
16098 on top of the input labelled "in":
16100 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
16101 [in] setpts=PTS-STARTPTS [main];
16102 [main][over] overlay=16:16 [out]
16106 Read from a video4linux2 device, and overlay it on top of the input
16109 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
16110 [in] setpts=PTS-STARTPTS [main];
16111 [main][over] overlay=16:16 [out]
16115 Read the first video stream and the audio stream with id 0x81 from
16116 dvd.vob; the video is connected to the pad named "video" and the audio is
16117 connected to the pad named "audio":
16119 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
16123 @c man end MULTIMEDIA SOURCES