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.
2370 Apply a flanging effect to the audio.
2372 The filter accepts the following options:
2376 Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
2379 Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2.
2382 Set percentage regeneration (delayed signal feedback). Range from -95 to 95.
2386 Set percentage of delayed signal mixed with original. Range from 0 to 100.
2387 Default value is 71.
2390 Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
2393 Set swept wave shape, can be @var{triangular} or @var{sinusoidal}.
2394 Default value is @var{sinusoidal}.
2397 Set swept wave percentage-shift for multi channel. Range from 0 to 100.
2398 Default value is 25.
2401 Set delay-line interpolation, @var{linear} or @var{quadratic}.
2402 Default is @var{linear}.
2407 Apply a high-pass filter with 3dB point frequency.
2408 The filter can be either single-pole, or double-pole (the default).
2409 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2411 The filter accepts the following options:
2415 Set frequency in Hz. Default is 3000.
2418 Set number of poles. Default is 2.
2421 Set method to specify band-width of filter.
2434 Specify the band-width of a filter in width_type units.
2435 Applies only to double-pole filter.
2436 The default is 0.707q and gives a Butterworth response.
2441 Join multiple input streams into one multi-channel stream.
2443 It accepts the following parameters:
2447 The number of input streams. It defaults to 2.
2449 @item channel_layout
2450 The desired output channel layout. It defaults to stereo.
2453 Map channels from inputs to output. The argument is a '|'-separated list of
2454 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
2455 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
2456 can be either the name of the input channel (e.g. FL for front left) or its
2457 index in the specified input stream. @var{out_channel} is the name of the output
2461 The filter will attempt to guess the mappings when they are not specified
2462 explicitly. It does so by first trying to find an unused matching input channel
2463 and if that fails it picks the first unused input channel.
2465 Join 3 inputs (with properly set channel layouts):
2467 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
2470 Build a 5.1 output from 6 single-channel streams:
2472 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
2473 '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'
2479 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
2481 To enable compilation of this filter you need to configure FFmpeg with
2482 @code{--enable-ladspa}.
2486 Specifies the name of LADSPA plugin library to load. If the environment
2487 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
2488 each one of the directories specified by the colon separated list in
2489 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
2490 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
2491 @file{/usr/lib/ladspa/}.
2494 Specifies the plugin within the library. Some libraries contain only
2495 one plugin, but others contain many of them. If this is not set filter
2496 will list all available plugins within the specified library.
2499 Set the '|' separated list of controls which are zero or more floating point
2500 values that determine the behavior of the loaded plugin (for example delay,
2502 Controls need to be defined using the following syntax:
2503 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
2504 @var{valuei} is the value set on the @var{i}-th control.
2505 Alternatively they can be also defined using the following syntax:
2506 @var{value0}|@var{value1}|@var{value2}|..., where
2507 @var{valuei} is the value set on the @var{i}-th control.
2508 If @option{controls} is set to @code{help}, all available controls and
2509 their valid ranges are printed.
2511 @item sample_rate, s
2512 Specify the sample rate, default to 44100. Only used if plugin have
2516 Set the number of samples per channel per each output frame, default
2517 is 1024. Only used if plugin have zero inputs.
2520 Set the minimum duration of the sourced audio. See
2521 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2522 for the accepted syntax.
2523 Note that the resulting duration may be greater than the specified duration,
2524 as the generated audio is always cut at the end of a complete frame.
2525 If not specified, or the expressed duration is negative, the audio is
2526 supposed to be generated forever.
2527 Only used if plugin have zero inputs.
2531 @subsection Examples
2535 List all available plugins within amp (LADSPA example plugin) library:
2541 List all available controls and their valid ranges for @code{vcf_notch}
2542 plugin from @code{VCF} library:
2544 ladspa=f=vcf:p=vcf_notch:c=help
2548 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
2551 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
2555 Add reverberation to the audio using TAP-plugins
2556 (Tom's Audio Processing plugins):
2558 ladspa=file=tap_reverb:tap_reverb
2562 Generate white noise, with 0.2 amplitude:
2564 ladspa=file=cmt:noise_source_white:c=c0=.2
2568 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
2569 @code{C* Audio Plugin Suite} (CAPS) library:
2571 ladspa=file=caps:Click:c=c1=20'
2575 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
2577 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
2581 Increase volume by 20dB using fast lookahead limiter from Steve Harris
2582 @code{SWH Plugins} collection:
2584 ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2
2588 Attenuate low frequencies using Multiband EQ from Steve Harris
2589 @code{SWH Plugins} collection:
2591 ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0
2595 @subsection Commands
2597 This filter supports the following commands:
2600 Modify the @var{N}-th control value.
2602 If the specified value is not valid, it is ignored and prior one is kept.
2607 Apply a low-pass filter with 3dB point frequency.
2608 The filter can be either single-pole or double-pole (the default).
2609 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2611 The filter accepts the following options:
2615 Set frequency in Hz. Default is 500.
2618 Set number of poles. Default is 2.
2621 Set method to specify band-width of filter.
2634 Specify the band-width of a filter in width_type units.
2635 Applies only to double-pole filter.
2636 The default is 0.707q and gives a Butterworth response.
2642 Mix channels with specific gain levels. The filter accepts the output
2643 channel layout followed by a set of channels definitions.
2645 This filter is also designed to efficiently remap the channels of an audio
2648 The filter accepts parameters of the form:
2649 "@var{l}|@var{outdef}|@var{outdef}|..."
2653 output channel layout or number of channels
2656 output channel specification, of the form:
2657 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
2660 output channel to define, either a channel name (FL, FR, etc.) or a channel
2661 number (c0, c1, etc.)
2664 multiplicative coefficient for the channel, 1 leaving the volume unchanged
2667 input channel to use, see out_name for details; it is not possible to mix
2668 named and numbered input channels
2671 If the `=' in a channel specification is replaced by `<', then the gains for
2672 that specification will be renormalized so that the total is 1, thus
2673 avoiding clipping noise.
2675 @subsection Mixing examples
2677 For example, if you want to down-mix from stereo to mono, but with a bigger
2678 factor for the left channel:
2680 pan=1c|c0=0.9*c0+0.1*c1
2683 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
2684 7-channels surround:
2686 pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
2689 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
2690 that should be preferred (see "-ac" option) unless you have very specific
2693 @subsection Remapping examples
2695 The channel remapping will be effective if, and only if:
2698 @item gain coefficients are zeroes or ones,
2699 @item only one input per channel output,
2702 If all these conditions are satisfied, the filter will notify the user ("Pure
2703 channel mapping detected"), and use an optimized and lossless method to do the
2706 For example, if you have a 5.1 source and want a stereo audio stream by
2707 dropping the extra channels:
2709 pan="stereo| c0=FL | c1=FR"
2712 Given the same source, you can also switch front left and front right channels
2713 and keep the input channel layout:
2715 pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
2718 If the input is a stereo audio stream, you can mute the front left channel (and
2719 still keep the stereo channel layout) with:
2724 Still with a stereo audio stream input, you can copy the right channel in both
2725 front left and right:
2727 pan="stereo| c0=FR | c1=FR"
2732 ReplayGain scanner filter. This filter takes an audio stream as an input and
2733 outputs it unchanged.
2734 At end of filtering it displays @code{track_gain} and @code{track_peak}.
2738 Convert the audio sample format, sample rate and channel layout. It is
2739 not meant to be used directly.
2742 Apply time-stretching and pitch-shifting with librubberband.
2744 The filter accepts the following options:
2748 Set tempo scale factor.
2751 Set pitch scale factor.
2754 Set transients detector.
2755 Possible values are:
2764 Possible values are:
2773 Possible values are:
2780 Set processing window size.
2781 Possible values are:
2790 Possible values are:
2797 Enable formant preservation when shift pitching.
2798 Possible values are:
2806 Possible values are:
2815 Possible values are:
2822 @section sidechaincompress
2824 This filter acts like normal compressor but has the ability to compress
2825 detected signal using second input signal.
2826 It needs two input streams and returns one output stream.
2827 First input stream will be processed depending on second stream signal.
2828 The filtered signal then can be filtered with other filters in later stages of
2829 processing. See @ref{pan} and @ref{amerge} filter.
2831 The filter accepts the following options:
2835 Set input gain. Default is 1. Range is between 0.015625 and 64.
2838 If a signal of second stream raises above this level it will affect the gain
2839 reduction of first stream.
2840 By default is 0.125. Range is between 0.00097563 and 1.
2843 Set a ratio about which the signal is reduced. 1:2 means that if the level
2844 raised 4dB above the threshold, it will be only 2dB above after the reduction.
2845 Default is 2. Range is between 1 and 20.
2848 Amount of milliseconds the signal has to rise above the threshold before gain
2849 reduction starts. Default is 20. Range is between 0.01 and 2000.
2852 Amount of milliseconds the signal has to fall below the threshold before
2853 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
2856 Set the amount by how much signal will be amplified after processing.
2857 Default is 2. Range is from 1 and 64.
2860 Curve the sharp knee around the threshold to enter gain reduction more softly.
2861 Default is 2.82843. Range is between 1 and 8.
2864 Choose if the @code{average} level between all channels of side-chain stream
2865 or the louder(@code{maximum}) channel of side-chain stream affects the
2866 reduction. Default is @code{average}.
2869 Should the exact signal be taken in case of @code{peak} or an RMS one in case
2870 of @code{rms}. Default is @code{rms} which is mainly smoother.
2873 Set sidechain gain. Default is 1. Range is between 0.015625 and 64.
2876 How much to use compressed signal in output. Default is 1.
2877 Range is between 0 and 1.
2880 @subsection Examples
2884 Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
2885 depending on the signal of 2nd input and later compressed signal to be
2886 merged with 2nd input:
2888 ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
2892 @section sidechaingate
2894 A sidechain gate acts like a normal (wideband) gate but has the ability to
2895 filter the detected signal before sending it to the gain reduction stage.
2896 Normally a gate uses the full range signal to detect a level above the
2898 For example: If you cut all lower frequencies from your sidechain signal
2899 the gate will decrease the volume of your track only if not enough highs
2900 appear. With this technique you are able to reduce the resonation of a
2901 natural drum or remove "rumbling" of muted strokes from a heavily distorted
2903 It needs two input streams and returns one output stream.
2904 First input stream will be processed depending on second stream signal.
2906 The filter accepts the following options:
2910 Set input level before filtering.
2911 Default is 1. Allowed range is from 0.015625 to 64.
2914 Set the level of gain reduction when the signal is below the threshold.
2915 Default is 0.06125. Allowed range is from 0 to 1.
2918 If a signal rises above this level the gain reduction is released.
2919 Default is 0.125. Allowed range is from 0 to 1.
2922 Set a ratio about which the signal is reduced.
2923 Default is 2. Allowed range is from 1 to 9000.
2926 Amount of milliseconds the signal has to rise above the threshold before gain
2928 Default is 20 milliseconds. Allowed range is from 0.01 to 9000.
2931 Amount of milliseconds the signal has to fall below the threshold before the
2932 reduction is increased again. Default is 250 milliseconds.
2933 Allowed range is from 0.01 to 9000.
2936 Set amount of amplification of signal after processing.
2937 Default is 1. Allowed range is from 1 to 64.
2940 Curve the sharp knee around the threshold to enter gain reduction more softly.
2941 Default is 2.828427125. Allowed range is from 1 to 8.
2944 Choose if exact signal should be taken for detection or an RMS like one.
2945 Default is rms. Can be peak or rms.
2948 Choose if the average level between all channels or the louder channel affects
2950 Default is average. Can be average or maximum.
2953 Set sidechain gain. Default is 1. Range is from 0.015625 to 64.
2956 @section silencedetect
2958 Detect silence in an audio stream.
2960 This filter logs a message when it detects that the input audio volume is less
2961 or equal to a noise tolerance value for a duration greater or equal to the
2962 minimum detected noise duration.
2964 The printed times and duration are expressed in seconds.
2966 The filter accepts the following options:
2970 Set silence duration until notification (default is 2 seconds).
2973 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
2974 specified value) or amplitude ratio. Default is -60dB, or 0.001.
2977 @subsection Examples
2981 Detect 5 seconds of silence with -50dB noise tolerance:
2983 silencedetect=n=-50dB:d=5
2987 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
2988 tolerance in @file{silence.mp3}:
2990 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
2994 @section silenceremove
2996 Remove silence from the beginning, middle or end of the audio.
2998 The filter accepts the following options:
3002 This value is used to indicate if audio should be trimmed at beginning of
3003 the audio. A value of zero indicates no silence should be trimmed from the
3004 beginning. When specifying a non-zero value, it trims audio up until it
3005 finds non-silence. Normally, when trimming silence from beginning of audio
3006 the @var{start_periods} will be @code{1} but it can be increased to higher
3007 values to trim all audio up to specific count of non-silence periods.
3008 Default value is @code{0}.
3010 @item start_duration
3011 Specify the amount of time that non-silence must be detected before it stops
3012 trimming audio. By increasing the duration, bursts of noises can be treated
3013 as silence and trimmed off. Default value is @code{0}.
3015 @item start_threshold
3016 This indicates what sample value should be treated as silence. For digital
3017 audio, a value of @code{0} may be fine but for audio recorded from analog,
3018 you may wish to increase the value to account for background noise.
3019 Can be specified in dB (in case "dB" is appended to the specified value)
3020 or amplitude ratio. Default value is @code{0}.
3023 Set the count for trimming silence from the end of audio.
3024 To remove silence from the middle of a file, specify a @var{stop_periods}
3025 that is negative. This value is then treated as a positive value and is
3026 used to indicate the effect should restart processing as specified by
3027 @var{start_periods}, making it suitable for removing periods of silence
3028 in the middle of the audio.
3029 Default value is @code{0}.
3032 Specify a duration of silence that must exist before audio is not copied any
3033 more. By specifying a higher duration, silence that is wanted can be left in
3035 Default value is @code{0}.
3037 @item stop_threshold
3038 This is the same as @option{start_threshold} but for trimming silence from
3040 Can be specified in dB (in case "dB" is appended to the specified value)
3041 or amplitude ratio. Default value is @code{0}.
3044 This indicate that @var{stop_duration} length of audio should be left intact
3045 at the beginning of each period of silence.
3046 For example, if you want to remove long pauses between words but do not want
3047 to remove the pauses completely. Default value is @code{0}.
3050 Set how is silence detected. Can be @code{rms} or @code{peak}. Second is faster
3051 and works better with digital silence which is exactly 0.
3052 Default value is @code{rms}.
3055 Set ratio used to calculate size of window for detecting silence.
3056 Default value is @code{0.02}. Allowed range is from @code{0} to @code{10}.
3059 @subsection Examples
3063 The following example shows how this filter can be used to start a recording
3064 that does not contain the delay at the start which usually occurs between
3065 pressing the record button and the start of the performance:
3067 silenceremove=1:5:0.02
3071 Trim all silence encountered from begining to end where there is more than 1
3072 second of silence in audio:
3074 silenceremove=0:0:0:-1:1:-90dB
3080 SOFAlizer uses head-related transfer functions (HRTFs) to create virtual
3081 loudspeakers around the user for binaural listening via headphones (audio
3082 formats up to 9 channels supported).
3083 The HRTFs are stored in SOFA files (see @url{http://www.sofacoustics.org/} for a database).
3084 SOFAlizer is developed at the Acoustics Research Institute (ARI) of the
3085 Austrian Academy of Sciences.
3087 To enable compilation of this filter you need to configure FFmpeg with
3088 @code{--enable-netcdf}.
3090 The filter accepts the following options:
3094 Set the SOFA file used for rendering.
3097 Set gain applied to audio. Value is in dB. Default is 0.
3100 Set rotation of virtual loudspeakers in deg. Default is 0.
3103 Set elevation of virtual speakers in deg. Default is 0.
3106 Set distance in meters between loudspeakers and the listener with near-field
3107 HRTFs. Default is 1.
3110 Set processing type. Can be @var{time} or @var{freq}. @var{time} is
3111 processing audio in time domain which is slow but gives high quality output.
3112 @var{freq} is processing audio in frequency domain which is fast but gives
3113 mediocre output. Default is @var{freq}.
3116 @section stereotools
3118 This filter has some handy utilities to manage stereo signals, for converting
3119 M/S stereo recordings to L/R signal while having control over the parameters
3120 or spreading the stereo image of master track.
3122 The filter accepts the following options:
3126 Set input level before filtering for both channels. Defaults is 1.
3127 Allowed range is from 0.015625 to 64.
3130 Set output level after filtering for both channels. Defaults is 1.
3131 Allowed range is from 0.015625 to 64.
3134 Set input balance between both channels. Default is 0.
3135 Allowed range is from -1 to 1.
3138 Set output balance between both channels. Default is 0.
3139 Allowed range is from -1 to 1.
3142 Enable softclipping. Results in analog distortion instead of harsh digital 0dB
3143 clipping. Disabled by default.
3146 Mute the left channel. Disabled by default.
3149 Mute the right channel. Disabled by default.
3152 Change the phase of the left channel. Disabled by default.
3155 Change the phase of the right channel. Disabled by default.
3158 Set stereo mode. Available values are:
3162 Left/Right to Left/Right, this is default.
3165 Left/Right to Mid/Side.
3168 Mid/Side to Left/Right.
3171 Left/Right to Left/Left.
3174 Left/Right to Right/Right.
3177 Left/Right to Left + Right.
3180 Left/Right to Right/Left.
3184 Set level of side signal. Default is 1.
3185 Allowed range is from 0.015625 to 64.
3188 Set balance of side signal. Default is 0.
3189 Allowed range is from -1 to 1.
3192 Set level of the middle signal. Default is 1.
3193 Allowed range is from 0.015625 to 64.
3196 Set middle signal pan. Default is 0. Allowed range is from -1 to 1.
3199 Set stereo base between mono and inversed channels. Default is 0.
3200 Allowed range is from -1 to 1.
3203 Set delay in milliseconds how much to delay left from right channel and
3204 vice versa. Default is 0. Allowed range is from -20 to 20.
3207 Set S/C level. Default is 1. Allowed range is from 1 to 100.
3210 Set the stereo phase in degrees. Default is 0. Allowed range is from 0 to 360.
3213 @section stereowiden
3215 This filter enhance the stereo effect by suppressing signal common to both
3216 channels and by delaying the signal of left into right and vice versa,
3217 thereby widening the stereo effect.
3219 The filter accepts the following options:
3223 Time in milliseconds of the delay of left signal into right and vice versa.
3224 Default is 20 milliseconds.
3227 Amount of gain in delayed signal into right and vice versa. Gives a delay
3228 effect of left signal in right output and vice versa which gives widening
3229 effect. Default is 0.3.
3232 Cross feed of left into right with inverted phase. This helps in suppressing
3233 the mono. If the value is 1 it will cancel all the signal common to both
3234 channels. Default is 0.3.
3237 Set level of input signal of original channel. Default is 0.8.
3242 Boost or cut treble (upper) frequencies of the audio using a two-pole
3243 shelving filter with a response similar to that of a standard
3244 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
3246 The filter accepts the following options:
3250 Give the gain at whichever is the lower of ~22 kHz and the
3251 Nyquist frequency. Its useful range is about -20 (for a large cut)
3252 to +20 (for a large boost). Beware of clipping when using a positive gain.
3255 Set the filter's central frequency and so can be used
3256 to extend or reduce the frequency range to be boosted or cut.
3257 The default value is @code{3000} Hz.
3260 Set method to specify band-width of filter.
3273 Determine how steep is the filter's shelf transition.
3278 Sinusoidal amplitude modulation.
3280 The filter accepts the following options:
3284 Modulation frequency in Hertz. Modulation frequencies in the subharmonic range
3285 (20 Hz or lower) will result in a tremolo effect.
3286 This filter may also be used as a ring modulator by specifying
3287 a modulation frequency higher than 20 Hz.
3288 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
3291 Depth of modulation as a percentage. Range is 0.0 - 1.0.
3292 Default value is 0.5.
3297 Sinusoidal phase modulation.
3299 The filter accepts the following options:
3303 Modulation frequency in Hertz.
3304 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
3307 Depth of modulation as a percentage. Range is 0.0 - 1.0.
3308 Default value is 0.5.
3313 Adjust the input audio volume.
3315 It accepts the following parameters:
3319 Set audio volume expression.
3321 Output values are clipped to the maximum value.
3323 The output audio volume is given by the relation:
3325 @var{output_volume} = @var{volume} * @var{input_volume}
3328 The default value for @var{volume} is "1.0".
3331 This parameter represents the mathematical precision.
3333 It determines which input sample formats will be allowed, which affects the
3334 precision of the volume scaling.
3338 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
3340 32-bit floating-point; this limits input sample format to FLT. (default)
3342 64-bit floating-point; this limits input sample format to DBL.
3346 Choose the behaviour on encountering ReplayGain side data in input frames.
3350 Remove ReplayGain side data, ignoring its contents (the default).
3353 Ignore ReplayGain side data, but leave it in the frame.
3356 Prefer the track gain, if present.
3359 Prefer the album gain, if present.
3362 @item replaygain_preamp
3363 Pre-amplification gain in dB to apply to the selected replaygain gain.
3365 Default value for @var{replaygain_preamp} is 0.0.
3368 Set when the volume expression is evaluated.
3370 It accepts the following values:
3373 only evaluate expression once during the filter initialization, or
3374 when the @samp{volume} command is sent
3377 evaluate expression for each incoming frame
3380 Default value is @samp{once}.
3383 The volume expression can contain the following parameters.
3387 frame number (starting at zero)
3390 @item nb_consumed_samples
3391 number of samples consumed by the filter
3393 number of samples in the current frame
3395 original frame position in the file
3401 PTS at start of stream
3403 time at start of stream
3409 last set volume value
3412 Note that when @option{eval} is set to @samp{once} only the
3413 @var{sample_rate} and @var{tb} variables are available, all other
3414 variables will evaluate to NAN.
3416 @subsection Commands
3418 This filter supports the following commands:
3421 Modify the volume expression.
3422 The command accepts the same syntax of the corresponding option.
3424 If the specified expression is not valid, it is kept at its current
3426 @item replaygain_noclip
3427 Prevent clipping by limiting the gain applied.
3429 Default value for @var{replaygain_noclip} is 1.
3433 @subsection Examples
3437 Halve the input audio volume:
3441 volume=volume=-6.0206dB
3444 In all the above example the named key for @option{volume} can be
3445 omitted, for example like in:
3451 Increase input audio power by 6 decibels using fixed-point precision:
3453 volume=volume=6dB:precision=fixed
3457 Fade volume after time 10 with an annihilation period of 5 seconds:
3459 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
3463 @section volumedetect
3465 Detect the volume of the input video.
3467 The filter has no parameters. The input is not modified. Statistics about
3468 the volume will be printed in the log when the input stream end is reached.
3470 In particular it will show the mean volume (root mean square), maximum
3471 volume (on a per-sample basis), and the beginning of a histogram of the
3472 registered volume values (from the maximum value to a cumulated 1/1000 of
3475 All volumes are in decibels relative to the maximum PCM value.
3477 @subsection Examples
3479 Here is an excerpt of the output:
3481 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
3482 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
3483 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
3484 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
3485 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
3486 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
3487 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
3488 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
3489 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
3495 The mean square energy is approximately -27 dB, or 10^-2.7.
3497 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
3499 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
3502 In other words, raising the volume by +4 dB does not cause any clipping,
3503 raising it by +5 dB causes clipping for 6 samples, etc.
3505 @c man end AUDIO FILTERS
3507 @chapter Audio Sources
3508 @c man begin AUDIO SOURCES
3510 Below is a description of the currently available audio sources.
3514 Buffer audio frames, and make them available to the filter chain.
3516 This source is mainly intended for a programmatic use, in particular
3517 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
3519 It accepts the following parameters:
3523 The timebase which will be used for timestamps of submitted frames. It must be
3524 either a floating-point number or in @var{numerator}/@var{denominator} form.
3527 The sample rate of the incoming audio buffers.
3530 The sample format of the incoming audio buffers.
3531 Either a sample format name or its corresponding integer representation from
3532 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
3534 @item channel_layout
3535 The channel layout of the incoming audio buffers.
3536 Either a channel layout name from channel_layout_map in
3537 @file{libavutil/channel_layout.c} or its corresponding integer representation
3538 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
3541 The number of channels of the incoming audio buffers.
3542 If both @var{channels} and @var{channel_layout} are specified, then they
3547 @subsection Examples
3550 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
3553 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
3554 Since the sample format with name "s16p" corresponds to the number
3555 6 and the "stereo" channel layout corresponds to the value 0x3, this is
3558 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
3563 Generate an audio signal specified by an expression.
3565 This source accepts in input one or more expressions (one for each
3566 channel), which are evaluated and used to generate a corresponding
3569 This source accepts the following options:
3573 Set the '|'-separated expressions list for each separate channel. In case the
3574 @option{channel_layout} option is not specified, the selected channel layout
3575 depends on the number of provided expressions. Otherwise the last
3576 specified expression is applied to the remaining output channels.
3578 @item channel_layout, c
3579 Set the channel layout. The number of channels in the specified layout
3580 must be equal to the number of specified expressions.
3583 Set the minimum duration of the sourced audio. See
3584 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
3585 for the accepted syntax.
3586 Note that the resulting duration may be greater than the specified
3587 duration, as the generated audio is always cut at the end of a
3590 If not specified, or the expressed duration is negative, the audio is
3591 supposed to be generated forever.
3594 Set the number of samples per channel per each output frame,
3597 @item sample_rate, s
3598 Specify the sample rate, default to 44100.
3601 Each expression in @var{exprs} can contain the following constants:
3605 number of the evaluated sample, starting from 0
3608 time of the evaluated sample expressed in seconds, starting from 0
3615 @subsection Examples
3625 Generate a sin signal with frequency of 440 Hz, set sample rate to
3628 aevalsrc="sin(440*2*PI*t):s=8000"
3632 Generate a two channels signal, specify the channel layout (Front
3633 Center + Back Center) explicitly:
3635 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
3639 Generate white noise:
3641 aevalsrc="-2+random(0)"
3645 Generate an amplitude modulated signal:
3647 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
3651 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
3653 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
3660 The null audio source, return unprocessed audio frames. It is mainly useful
3661 as a template and to be employed in analysis / debugging tools, or as
3662 the source for filters which ignore the input data (for example the sox
3665 This source accepts the following options:
3669 @item channel_layout, cl
3671 Specifies the channel layout, and can be either an integer or a string
3672 representing a channel layout. The default value of @var{channel_layout}
3675 Check the channel_layout_map definition in
3676 @file{libavutil/channel_layout.c} for the mapping between strings and
3677 channel layout values.
3679 @item sample_rate, r
3680 Specifies the sample rate, and defaults to 44100.
3683 Set the number of samples per requested frames.
3687 @subsection Examples
3691 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
3693 anullsrc=r=48000:cl=4
3697 Do the same operation with a more obvious syntax:
3699 anullsrc=r=48000:cl=mono
3703 All the parameters need to be explicitly defined.
3707 Synthesize a voice utterance using the libflite library.
3709 To enable compilation of this filter you need to configure FFmpeg with
3710 @code{--enable-libflite}.
3712 Note that the flite library is not thread-safe.
3714 The filter accepts the following options:
3719 If set to 1, list the names of the available voices and exit
3720 immediately. Default value is 0.
3723 Set the maximum number of samples per frame. Default value is 512.
3726 Set the filename containing the text to speak.
3729 Set the text to speak.
3732 Set the voice to use for the speech synthesis. Default value is
3733 @code{kal}. See also the @var{list_voices} option.
3736 @subsection Examples
3740 Read from file @file{speech.txt}, and synthesize the text using the
3741 standard flite voice:
3743 flite=textfile=speech.txt
3747 Read the specified text selecting the @code{slt} voice:
3749 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3753 Input text to ffmpeg:
3755 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3759 Make @file{ffplay} speak the specified text, using @code{flite} and
3760 the @code{lavfi} device:
3762 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
3766 For more information about libflite, check:
3767 @url{http://www.speech.cs.cmu.edu/flite/}
3771 Generate a noise audio signal.
3773 The filter accepts the following options:
3776 @item sample_rate, r
3777 Specify the sample rate. Default value is 48000 Hz.
3780 Specify the amplitude (0.0 - 1.0) of the generated audio stream. Default value
3784 Specify the duration of the generated audio stream. Not specifying this option
3785 results in noise with an infinite length.
3787 @item color, colour, c
3788 Specify the color of noise. Available noise colors are white, pink, and brown.
3789 Default color is white.
3792 Specify a value used to seed the PRNG.
3795 Set the number of samples per each output frame, default is 1024.
3798 @subsection Examples
3803 Generate 60 seconds of pink noise, with a 44.1 kHz sampling rate and an amplitude of 0.5:
3805 anoisesrc=d=60:c=pink:r=44100:a=0.5
3811 Generate an audio signal made of a sine wave with amplitude 1/8.
3813 The audio signal is bit-exact.
3815 The filter accepts the following options:
3820 Set the carrier frequency. Default is 440 Hz.
3822 @item beep_factor, b
3823 Enable a periodic beep every second with frequency @var{beep_factor} times
3824 the carrier frequency. Default is 0, meaning the beep is disabled.
3826 @item sample_rate, r
3827 Specify the sample rate, default is 44100.
3830 Specify the duration of the generated audio stream.
3832 @item samples_per_frame
3833 Set the number of samples per output frame.
3835 The expression can contain the following constants:
3839 The (sequential) number of the output audio frame, starting from 0.
3842 The PTS (Presentation TimeStamp) of the output audio frame,
3843 expressed in @var{TB} units.
3846 The PTS of the output audio frame, expressed in seconds.
3849 The timebase of the output audio frames.
3852 Default is @code{1024}.
3855 @subsection Examples
3860 Generate a simple 440 Hz sine wave:
3866 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
3870 sine=frequency=220:beep_factor=4:duration=5
3874 Generate a 1 kHz sine wave following @code{1602,1601,1602,1601,1602} NTSC
3877 sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
3881 @c man end AUDIO SOURCES
3883 @chapter Audio Sinks
3884 @c man begin AUDIO SINKS
3886 Below is a description of the currently available audio sinks.
3888 @section abuffersink
3890 Buffer audio frames, and make them available to the end of filter chain.
3892 This sink is mainly intended for programmatic use, in particular
3893 through the interface defined in @file{libavfilter/buffersink.h}
3894 or the options system.
3896 It accepts a pointer to an AVABufferSinkContext structure, which
3897 defines the incoming buffers' formats, to be passed as the opaque
3898 parameter to @code{avfilter_init_filter} for initialization.
3901 Null audio sink; do absolutely nothing with the input audio. It is
3902 mainly useful as a template and for use in analysis / debugging
3905 @c man end AUDIO SINKS
3907 @chapter Video Filters
3908 @c man begin VIDEO FILTERS
3910 When you configure your FFmpeg build, you can disable any of the
3911 existing filters using @code{--disable-filters}.
3912 The configure output will show the video filters included in your
3915 Below is a description of the currently available video filters.
3917 @section alphaextract
3919 Extract the alpha component from the input as a grayscale video. This
3920 is especially useful with the @var{alphamerge} filter.
3924 Add or replace the alpha component of the primary input with the
3925 grayscale value of a second input. This is intended for use with
3926 @var{alphaextract} to allow the transmission or storage of frame
3927 sequences that have alpha in a format that doesn't support an alpha
3930 For example, to reconstruct full frames from a normal YUV-encoded video
3931 and a separate video created with @var{alphaextract}, you might use:
3933 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
3936 Since this filter is designed for reconstruction, it operates on frame
3937 sequences without considering timestamps, and terminates when either
3938 input reaches end of stream. This will cause problems if your encoding
3939 pipeline drops frames. If you're trying to apply an image as an
3940 overlay to a video stream, consider the @var{overlay} filter instead.
3944 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
3945 and libavformat to work. On the other hand, it is limited to ASS (Advanced
3946 Substation Alpha) subtitles files.
3948 This filter accepts the following option in addition to the common options from
3949 the @ref{subtitles} filter:
3953 Set the shaping engine
3955 Available values are:
3958 The default libass shaping engine, which is the best available.
3960 Fast, font-agnostic shaper that can do only substitutions
3962 Slower shaper using OpenType for substitutions and positioning
3965 The default is @code{auto}.
3969 Apply an Adaptive Temporal Averaging Denoiser to the video input.
3971 The filter accepts the following options:
3975 Set threshold A for 1st plane. Default is 0.02.
3976 Valid range is 0 to 0.3.
3979 Set threshold B for 1st plane. Default is 0.04.
3980 Valid range is 0 to 5.
3983 Set threshold A for 2nd plane. Default is 0.02.
3984 Valid range is 0 to 0.3.
3987 Set threshold B for 2nd plane. Default is 0.04.
3988 Valid range is 0 to 5.
3991 Set threshold A for 3rd plane. Default is 0.02.
3992 Valid range is 0 to 0.3.
3995 Set threshold B for 3rd plane. Default is 0.04.
3996 Valid range is 0 to 5.
3998 Threshold A is designed to react on abrupt changes in the input signal and
3999 threshold B is designed to react on continuous changes in the input signal.
4002 Set number of frames filter will use for averaging. Default is 33. Must be odd
4003 number in range [5, 129].
4008 Compute the bounding box for the non-black pixels in the input frame
4011 This filter computes the bounding box containing all the pixels with a
4012 luminance value greater than the minimum allowed value.
4013 The parameters describing the bounding box are printed on the filter
4016 The filter accepts the following option:
4020 Set the minimal luminance value. Default is @code{16}.
4023 @section blackdetect
4025 Detect video intervals that are (almost) completely black. Can be
4026 useful to detect chapter transitions, commercials, or invalid
4027 recordings. Output lines contains the time for the start, end and
4028 duration of the detected black interval expressed in seconds.
4030 In order to display the output lines, you need to set the loglevel at
4031 least to the AV_LOG_INFO value.
4033 The filter accepts the following options:
4036 @item black_min_duration, d
4037 Set the minimum detected black duration expressed in seconds. It must
4038 be a non-negative floating point number.
4040 Default value is 2.0.
4042 @item picture_black_ratio_th, pic_th
4043 Set the threshold for considering a picture "black".
4044 Express the minimum value for the ratio:
4046 @var{nb_black_pixels} / @var{nb_pixels}
4049 for which a picture is considered black.
4050 Default value is 0.98.
4052 @item pixel_black_th, pix_th
4053 Set the threshold for considering a pixel "black".
4055 The threshold expresses the maximum pixel luminance value for which a
4056 pixel is considered "black". The provided value is scaled according to
4057 the following equation:
4059 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
4062 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
4063 the input video format, the range is [0-255] for YUV full-range
4064 formats and [16-235] for YUV non full-range formats.
4066 Default value is 0.10.
4069 The following example sets the maximum pixel threshold to the minimum
4070 value, and detects only black intervals of 2 or more seconds:
4072 blackdetect=d=2:pix_th=0.00
4077 Detect frames that are (almost) completely black. Can be useful to
4078 detect chapter transitions or commercials. Output lines consist of
4079 the frame number of the detected frame, the percentage of blackness,
4080 the position in the file if known or -1 and the timestamp in seconds.
4082 In order to display the output lines, you need to set the loglevel at
4083 least to the AV_LOG_INFO value.
4085 It accepts the following parameters:
4090 The percentage of the pixels that have to be below the threshold; it defaults to
4093 @item threshold, thresh
4094 The threshold below which a pixel value is considered black; it defaults to
4099 @section blend, tblend
4101 Blend two video frames into each other.
4103 The @code{blend} filter takes two input streams and outputs one
4104 stream, the first input is the "top" layer and second input is
4105 "bottom" layer. Output terminates when shortest input terminates.
4107 The @code{tblend} (time blend) filter takes two consecutive frames
4108 from one single stream, and outputs the result obtained by blending
4109 the new frame on top of the old frame.
4111 A description of the accepted options follows.
4119 Set blend mode for specific pixel component or all pixel components in case
4120 of @var{all_mode}. Default value is @code{normal}.
4122 Available values for component modes are:
4160 Set blend opacity for specific pixel component or all pixel components in case
4161 of @var{all_opacity}. Only used in combination with pixel component blend modes.
4168 Set blend expression for specific pixel component or all pixel components in case
4169 of @var{all_expr}. Note that related mode options will be ignored if those are set.
4171 The expressions can use the following variables:
4175 The sequential number of the filtered frame, starting from @code{0}.
4179 the coordinates of the current sample
4183 the width and height of currently filtered plane
4187 Width and height scale depending on the currently filtered plane. It is the
4188 ratio between the corresponding luma plane number of pixels and the current
4189 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4190 @code{0.5,0.5} for chroma planes.
4193 Time of the current frame, expressed in seconds.
4196 Value of pixel component at current location for first video frame (top layer).
4199 Value of pixel component at current location for second video frame (bottom layer).
4203 Force termination when the shortest input terminates. Default is
4204 @code{0}. This option is only defined for the @code{blend} filter.
4207 Continue applying the last bottom frame after the end of the stream. A value of
4208 @code{0} disable the filter after the last frame of the bottom layer is reached.
4209 Default is @code{1}. This option is only defined for the @code{blend} filter.
4212 @subsection Examples
4216 Apply transition from bottom layer to top layer in first 10 seconds:
4218 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
4222 Apply 1x1 checkerboard effect:
4224 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
4228 Apply uncover left effect:
4230 blend=all_expr='if(gte(N*SW+X,W),A,B)'
4234 Apply uncover down effect:
4236 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
4240 Apply uncover up-left effect:
4242 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
4246 Display differences between the current and the previous frame:
4248 tblend=all_mode=difference128
4254 Apply a boxblur algorithm to the input video.
4256 It accepts the following parameters:
4260 @item luma_radius, lr
4261 @item luma_power, lp
4262 @item chroma_radius, cr
4263 @item chroma_power, cp
4264 @item alpha_radius, ar
4265 @item alpha_power, ap
4269 A description of the accepted options follows.
4272 @item luma_radius, lr
4273 @item chroma_radius, cr
4274 @item alpha_radius, ar
4275 Set an expression for the box radius in pixels used for blurring the
4276 corresponding input plane.
4278 The radius value must be a non-negative number, and must not be
4279 greater than the value of the expression @code{min(w,h)/2} for the
4280 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
4283 Default value for @option{luma_radius} is "2". If not specified,
4284 @option{chroma_radius} and @option{alpha_radius} default to the
4285 corresponding value set for @option{luma_radius}.
4287 The expressions can contain the following constants:
4291 The input width and height in pixels.
4295 The input chroma image width and height in pixels.
4299 The horizontal and vertical chroma subsample values. For example, for the
4300 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
4303 @item luma_power, lp
4304 @item chroma_power, cp
4305 @item alpha_power, ap
4306 Specify how many times the boxblur filter is applied to the
4307 corresponding plane.
4309 Default value for @option{luma_power} is 2. If not specified,
4310 @option{chroma_power} and @option{alpha_power} default to the
4311 corresponding value set for @option{luma_power}.
4313 A value of 0 will disable the effect.
4316 @subsection Examples
4320 Apply a boxblur filter with the luma, chroma, and alpha radii
4323 boxblur=luma_radius=2:luma_power=1
4328 Set the luma radius to 2, and alpha and chroma radius to 0:
4330 boxblur=2:1:cr=0:ar=0
4334 Set the luma and chroma radii to a fraction of the video dimension:
4336 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
4341 YUV colorspace color/chroma keying.
4343 The filter accepts the following options:
4347 The color which will be replaced with transparency.
4350 Similarity percentage with the key color.
4352 0.01 matches only the exact key color, while 1.0 matches everything.
4357 0.0 makes pixels either fully transparent, or not transparent at all.
4359 Higher values result in semi-transparent pixels, with a higher transparency
4360 the more similar the pixels color is to the key color.
4363 Signals that the color passed is already in YUV instead of RGB.
4365 Litteral colors like "green" or "red" don't make sense with this enabled anymore.
4366 This can be used to pass exact YUV values as hexadecimal numbers.
4369 @subsection Examples
4373 Make every green pixel in the input image transparent:
4375 ffmpeg -i input.png -vf chromakey=green out.png
4379 Overlay a greenscreen-video on top of a static black background.
4381 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
4387 Visualize information exported by some codecs.
4389 Some codecs can export information through frames using side-data or other
4390 means. For example, some MPEG based codecs export motion vectors through the
4391 @var{export_mvs} flag in the codec @option{flags2} option.
4393 The filter accepts the following option:
4397 Set motion vectors to visualize.
4399 Available flags for @var{mv} are:
4403 forward predicted MVs of P-frames
4405 forward predicted MVs of B-frames
4407 backward predicted MVs of B-frames
4411 Display quantization parameters using the chroma planes
4414 @subsection Examples
4418 Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}:
4420 ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
4424 @section colorbalance
4425 Modify intensity of primary colors (red, green and blue) of input frames.
4427 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
4428 regions for the red-cyan, green-magenta or blue-yellow balance.
4430 A positive adjustment value shifts the balance towards the primary color, a negative
4431 value towards the complementary color.
4433 The filter accepts the following options:
4439 Adjust red, green and blue shadows (darkest pixels).
4444 Adjust red, green and blue midtones (medium pixels).
4449 Adjust red, green and blue highlights (brightest pixels).
4451 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
4454 @subsection Examples
4458 Add red color cast to shadows:
4465 RGB colorspace color keying.
4467 The filter accepts the following options:
4471 The color which will be replaced with transparency.
4474 Similarity percentage with the key color.
4476 0.01 matches only the exact key color, while 1.0 matches everything.
4481 0.0 makes pixels either fully transparent, or not transparent at all.
4483 Higher values result in semi-transparent pixels, with a higher transparency
4484 the more similar the pixels color is to the key color.
4487 @subsection Examples
4491 Make every green pixel in the input image transparent:
4493 ffmpeg -i input.png -vf colorkey=green out.png
4497 Overlay a greenscreen-video on top of a static background image.
4499 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
4503 @section colorlevels
4505 Adjust video input frames using levels.
4507 The filter accepts the following options:
4514 Adjust red, green, blue and alpha input black point.
4515 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
4521 Adjust red, green, blue and alpha input white point.
4522 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{1}.
4524 Input levels are used to lighten highlights (bright tones), darken shadows
4525 (dark tones), change the balance of bright and dark tones.
4531 Adjust red, green, blue and alpha output black point.
4532 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{0}.
4538 Adjust red, green, blue and alpha output white point.
4539 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{1}.
4541 Output levels allows manual selection of a constrained output level range.
4544 @subsection Examples
4548 Make video output darker:
4550 colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
4556 colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
4560 Make video output lighter:
4562 colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
4566 Increase brightness:
4568 colorlevels=romin=0.5:gomin=0.5:bomin=0.5
4572 @section colorchannelmixer
4574 Adjust video input frames by re-mixing color channels.
4576 This filter modifies a color channel by adding the values associated to
4577 the other channels of the same pixels. For example if the value to
4578 modify is red, the output value will be:
4580 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
4583 The filter accepts the following options:
4590 Adjust contribution of input red, green, blue and alpha channels for output red channel.
4591 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
4597 Adjust contribution of input red, green, blue and alpha channels for output green channel.
4598 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
4604 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
4605 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
4611 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
4612 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
4614 Allowed ranges for options are @code{[-2.0, 2.0]}.
4617 @subsection Examples
4621 Convert source to grayscale:
4623 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
4626 Simulate sepia tones:
4628 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
4632 @section colormatrix
4634 Convert color matrix.
4636 The filter accepts the following options:
4641 Specify the source and destination color matrix. Both values must be
4644 The accepted values are:
4660 For example to convert from BT.601 to SMPTE-240M, use the command:
4662 colormatrix=bt601:smpte240m
4665 @section convolution
4667 Apply convolution 3x3 or 5x5 filter.
4669 The filter accepts the following options:
4676 Set matrix for each plane.
4677 Matrix is sequence of 9 or 25 signed integers.
4683 Set multiplier for calculated value for each plane.
4689 Set bias for each plane. This value is added to the result of the multiplication.
4690 Useful for making the overall image brighter or darker. Default is 0.0.
4693 @subsection Examples
4699 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"
4705 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"
4711 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"
4717 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"
4723 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"
4729 Copy the input source unchanged to the output. This is mainly useful for
4734 Crop the input video to given dimensions.
4736 It accepts the following parameters:
4740 The width of the output video. It defaults to @code{iw}.
4741 This expression is evaluated only once during the filter
4742 configuration, or when the @samp{w} or @samp{out_w} command is sent.
4745 The height of the output video. It defaults to @code{ih}.
4746 This expression is evaluated only once during the filter
4747 configuration, or when the @samp{h} or @samp{out_h} command is sent.
4750 The horizontal position, in the input video, of the left edge of the output
4751 video. It defaults to @code{(in_w-out_w)/2}.
4752 This expression is evaluated per-frame.
4755 The vertical position, in the input video, of the top edge of the output video.
4756 It defaults to @code{(in_h-out_h)/2}.
4757 This expression is evaluated per-frame.
4760 If set to 1 will force the output display aspect ratio
4761 to be the same of the input, by changing the output sample aspect
4762 ratio. It defaults to 0.
4765 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
4766 expressions containing the following constants:
4771 The computed values for @var{x} and @var{y}. They are evaluated for
4776 The input width and height.
4780 These are the same as @var{in_w} and @var{in_h}.
4784 The output (cropped) width and height.
4788 These are the same as @var{out_w} and @var{out_h}.
4791 same as @var{iw} / @var{ih}
4794 input sample aspect ratio
4797 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4801 horizontal and vertical chroma subsample values. For example for the
4802 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4805 The number of the input frame, starting from 0.
4808 the position in the file of the input frame, NAN if unknown
4811 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
4815 The expression for @var{out_w} may depend on the value of @var{out_h},
4816 and the expression for @var{out_h} may depend on @var{out_w}, but they
4817 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
4818 evaluated after @var{out_w} and @var{out_h}.
4820 The @var{x} and @var{y} parameters specify the expressions for the
4821 position of the top-left corner of the output (non-cropped) area. They
4822 are evaluated for each frame. If the evaluated value is not valid, it
4823 is approximated to the nearest valid value.
4825 The expression for @var{x} may depend on @var{y}, and the expression
4826 for @var{y} may depend on @var{x}.
4828 @subsection Examples
4832 Crop area with size 100x100 at position (12,34).
4837 Using named options, the example above becomes:
4839 crop=w=100:h=100:x=12:y=34
4843 Crop the central input area with size 100x100:
4849 Crop the central input area with size 2/3 of the input video:
4851 crop=2/3*in_w:2/3*in_h
4855 Crop the input video central square:
4862 Delimit the rectangle with the top-left corner placed at position
4863 100:100 and the right-bottom corner corresponding to the right-bottom
4864 corner of the input image.
4866 crop=in_w-100:in_h-100:100:100
4870 Crop 10 pixels from the left and right borders, and 20 pixels from
4871 the top and bottom borders
4873 crop=in_w-2*10:in_h-2*20
4877 Keep only the bottom right quarter of the input image:
4879 crop=in_w/2:in_h/2:in_w/2:in_h/2
4883 Crop height for getting Greek harmony:
4885 crop=in_w:1/PHI*in_w
4889 Apply trembling effect:
4891 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)
4895 Apply erratic camera effect depending on timestamp:
4897 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)"
4901 Set x depending on the value of y:
4903 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
4907 @subsection Commands
4909 This filter supports the following commands:
4915 Set width/height of the output video and the horizontal/vertical position
4917 The command accepts the same syntax of the corresponding option.
4919 If the specified expression is not valid, it is kept at its current
4925 Auto-detect the crop size.
4927 It calculates the necessary cropping parameters and prints the
4928 recommended parameters via the logging system. The detected dimensions
4929 correspond to the non-black area of the input video.
4931 It accepts the following parameters:
4936 Set higher black value threshold, which can be optionally specified
4937 from nothing (0) to everything (255 for 8bit based formats). An intensity
4938 value greater to the set value is considered non-black. It defaults to 24.
4939 You can also specify a value between 0.0 and 1.0 which will be scaled depending
4940 on the bitdepth of the pixel format.
4943 The value which the width/height should be divisible by. It defaults to
4944 16. The offset is automatically adjusted to center the video. Use 2 to
4945 get only even dimensions (needed for 4:2:2 video). 16 is best when
4946 encoding to most video codecs.
4948 @item reset_count, reset
4949 Set the counter that determines after how many frames cropdetect will
4950 reset the previously detected largest video area and start over to
4951 detect the current optimal crop area. Default value is 0.
4953 This can be useful when channel logos distort the video area. 0
4954 indicates 'never reset', and returns the largest area encountered during
4961 Apply color adjustments using curves.
4963 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
4964 component (red, green and blue) has its values defined by @var{N} key points
4965 tied from each other using a smooth curve. The x-axis represents the pixel
4966 values from the input frame, and the y-axis the new pixel values to be set for
4969 By default, a component curve is defined by the two points @var{(0;0)} and
4970 @var{(1;1)}. This creates a straight line where each original pixel value is
4971 "adjusted" to its own value, which means no change to the image.
4973 The filter allows you to redefine these two points and add some more. A new
4974 curve (using a natural cubic spline interpolation) will be define to pass
4975 smoothly through all these new coordinates. The new defined points needs to be
4976 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
4977 be in the @var{[0;1]} interval. If the computed curves happened to go outside
4978 the vector spaces, the values will be clipped accordingly.
4980 If there is no key point defined in @code{x=0}, the filter will automatically
4981 insert a @var{(0;0)} point. In the same way, if there is no key point defined
4982 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
4984 The filter accepts the following options:
4988 Select one of the available color presets. This option can be used in addition
4989 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
4990 options takes priority on the preset values.
4991 Available presets are:
4994 @item color_negative
4997 @item increase_contrast
4999 @item linear_contrast
5000 @item medium_contrast
5002 @item strong_contrast
5005 Default is @code{none}.
5007 Set the master key points. These points will define a second pass mapping. It
5008 is sometimes called a "luminance" or "value" mapping. It can be used with
5009 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
5010 post-processing LUT.
5012 Set the key points for the red component.
5014 Set the key points for the green component.
5016 Set the key points for the blue component.
5018 Set the key points for all components (not including master).
5019 Can be used in addition to the other key points component
5020 options. In this case, the unset component(s) will fallback on this
5021 @option{all} setting.
5023 Specify a Photoshop curves file (@code{.acv}) to import the settings from.
5026 To avoid some filtergraph syntax conflicts, each key points list need to be
5027 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
5029 @subsection Examples
5033 Increase slightly the middle level of blue:
5035 curves=blue='0.5/0.58'
5041 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
5043 Here we obtain the following coordinates for each components:
5046 @code{(0;0.11) (0.42;0.51) (1;0.95)}
5048 @code{(0;0) (0.50;0.48) (1;1)}
5050 @code{(0;0.22) (0.49;0.44) (1;0.80)}
5054 The previous example can also be achieved with the associated built-in preset:
5056 curves=preset=vintage
5066 Use a Photoshop preset and redefine the points of the green component:
5068 curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'
5074 Denoise frames using 2D DCT (frequency domain filtering).
5076 This filter is not designed for real time.
5078 The filter accepts the following options:
5082 Set the noise sigma constant.
5084 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
5085 coefficient (absolute value) below this threshold with be dropped.
5087 If you need a more advanced filtering, see @option{expr}.
5089 Default is @code{0}.
5092 Set number overlapping pixels for each block. Since the filter can be slow, you
5093 may want to reduce this value, at the cost of a less effective filter and the
5094 risk of various artefacts.
5096 If the overlapping value doesn't permit processing the whole input width or
5097 height, a warning will be displayed and according borders won't be denoised.
5099 Default value is @var{blocksize}-1, which is the best possible setting.
5102 Set the coefficient factor expression.
5104 For each coefficient of a DCT block, this expression will be evaluated as a
5105 multiplier value for the coefficient.
5107 If this is option is set, the @option{sigma} option will be ignored.
5109 The absolute value of the coefficient can be accessed through the @var{c}
5113 Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the
5114 @var{blocksize}, which is the width and height of the processed blocks.
5116 The default value is @var{3} (8x8) and can be raised to @var{4} for a
5117 @var{blocksize} of 16x16. Note that changing this setting has huge consequences
5118 on the speed processing. Also, a larger block size does not necessarily means a
5122 @subsection Examples
5124 Apply a denoise with a @option{sigma} of @code{4.5}:
5129 The same operation can be achieved using the expression system:
5131 dctdnoiz=e='gte(c, 4.5*3)'
5134 Violent denoise using a block size of @code{16x16}:
5141 Remove banding artifacts from input video.
5142 It works by replacing banded pixels with average value of referenced pixels.
5144 The filter accepts the following options:
5151 Set banding detection threshold for each plane. Default is 0.02.
5152 Valid range is 0.00003 to 0.5.
5153 If difference between current pixel and reference pixel is less than threshold,
5154 it will be considered as banded.
5157 Banding detection range in pixels. Default is 16. If positive, random number
5158 in range 0 to set value will be used. If negative, exact absolute value
5160 The range defines square of four pixels around current pixel.
5163 Set direction in radians from which four pixel will be compared. If positive,
5164 random direction from 0 to set direction will be picked. If negative, exact of
5165 absolute value will be picked. For example direction 0, -PI or -2*PI radians
5166 will pick only pixels on same row and -PI/2 will pick only pixels on same
5170 If enabled, current pixel is compared with average value of all four
5171 surrounding pixels. The default is enabled. If disabled current pixel is
5172 compared with all four surrounding pixels. The pixel is considered banded
5173 if only all four differences with surrounding pixels are less than threshold.
5179 Drop duplicated frames at regular intervals.
5181 The filter accepts the following options:
5185 Set the number of frames from which one will be dropped. Setting this to
5186 @var{N} means one frame in every batch of @var{N} frames will be dropped.
5187 Default is @code{5}.
5190 Set the threshold for duplicate detection. If the difference metric for a frame
5191 is less than or equal to this value, then it is declared as duplicate. Default
5195 Set scene change threshold. Default is @code{15}.
5199 Set the size of the x and y-axis blocks used during metric calculations.
5200 Larger blocks give better noise suppression, but also give worse detection of
5201 small movements. Must be a power of two. Default is @code{32}.
5204 Mark main input as a pre-processed input and activate clean source input
5205 stream. This allows the input to be pre-processed with various filters to help
5206 the metrics calculation while keeping the frame selection lossless. When set to
5207 @code{1}, the first stream is for the pre-processed input, and the second
5208 stream is the clean source from where the kept frames are chosen. Default is
5212 Set whether or not chroma is considered in the metric calculations. Default is
5218 Apply deflate effect to the video.
5220 This filter replaces the pixel by the local(3x3) average by taking into account
5221 only values lower than the pixel.
5223 It accepts the following options:
5230 Limit the maximum change for each plane, default is 65535.
5231 If 0, plane will remain unchanged.
5236 Remove judder produced by partially interlaced telecined content.
5238 Judder can be introduced, for instance, by @ref{pullup} filter. If the original
5239 source was partially telecined content then the output of @code{pullup,dejudder}
5240 will have a variable frame rate. May change the recorded frame rate of the
5241 container. Aside from that change, this filter will not affect constant frame
5244 The option available in this filter is:
5248 Specify the length of the window over which the judder repeats.
5250 Accepts any integer greater than 1. Useful values are:
5254 If the original was telecined from 24 to 30 fps (Film to NTSC).
5257 If the original was telecined from 25 to 30 fps (PAL to NTSC).
5260 If a mixture of the two.
5263 The default is @samp{4}.
5268 Suppress a TV station logo by a simple interpolation of the surrounding
5269 pixels. Just set a rectangle covering the logo and watch it disappear
5270 (and sometimes something even uglier appear - your mileage may vary).
5272 It accepts the following parameters:
5277 Specify the top left corner coordinates of the logo. They must be
5282 Specify the width and height of the logo to clear. They must be
5286 Specify the thickness of the fuzzy edge of the rectangle (added to
5287 @var{w} and @var{h}). The default value is 1. This option is
5288 deprecated, setting higher values should no longer be necessary and
5292 When set to 1, a green rectangle is drawn on the screen to simplify
5293 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
5294 The default value is 0.
5296 The rectangle is drawn on the outermost pixels which will be (partly)
5297 replaced with interpolated values. The values of the next pixels
5298 immediately outside this rectangle in each direction will be used to
5299 compute the interpolated pixel values inside the rectangle.
5303 @subsection Examples
5307 Set a rectangle covering the area with top left corner coordinates 0,0
5308 and size 100x77, and a band of size 10:
5310 delogo=x=0:y=0:w=100:h=77:band=10
5317 Attempt to fix small changes in horizontal and/or vertical shift. This
5318 filter helps remove camera shake from hand-holding a camera, bumping a
5319 tripod, moving on a vehicle, etc.
5321 The filter accepts the following options:
5329 Specify a rectangular area where to limit the search for motion
5331 If desired the search for motion vectors can be limited to a
5332 rectangular area of the frame defined by its top left corner, width
5333 and height. These parameters have the same meaning as the drawbox
5334 filter which can be used to visualise the position of the bounding
5337 This is useful when simultaneous movement of subjects within the frame
5338 might be confused for camera motion by the motion vector search.
5340 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
5341 then the full frame is used. This allows later options to be set
5342 without specifying the bounding box for the motion vector search.
5344 Default - search the whole frame.
5348 Specify the maximum extent of movement in x and y directions in the
5349 range 0-64 pixels. Default 16.
5352 Specify how to generate pixels to fill blanks at the edge of the
5353 frame. Available values are:
5356 Fill zeroes at blank locations
5358 Original image at blank locations
5360 Extruded edge value at blank locations
5362 Mirrored edge at blank locations
5364 Default value is @samp{mirror}.
5367 Specify the blocksize to use for motion search. Range 4-128 pixels,
5371 Specify the contrast threshold for blocks. Only blocks with more than
5372 the specified contrast (difference between darkest and lightest
5373 pixels) will be considered. Range 1-255, default 125.
5376 Specify the search strategy. Available values are:
5379 Set exhaustive search
5381 Set less exhaustive search.
5383 Default value is @samp{exhaustive}.
5386 If set then a detailed log of the motion search is written to the
5390 If set to 1, specify using OpenCL capabilities, only available if
5391 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
5397 Apply an exact inverse of the telecine operation. It requires a predefined
5398 pattern specified using the pattern option which must be the same as that passed
5399 to the telecine filter.
5401 This filter accepts the following options:
5410 The default value is @code{top}.
5414 A string of numbers representing the pulldown pattern you wish to apply.
5415 The default value is @code{23}.
5418 A number representing position of the first frame with respect to the telecine
5419 pattern. This is to be used if the stream is cut. The default value is @code{0}.
5424 Apply dilation effect to the video.
5426 This filter replaces the pixel by the local(3x3) maximum.
5428 It accepts the following options:
5435 Limit the maximum change for each plane, default is 65535.
5436 If 0, plane will remain unchanged.
5439 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
5442 Flags to local 3x3 coordinates maps like this:
5451 Displace pixels as indicated by second and third input stream.
5453 It takes three input streams and outputs one stream, the first input is the
5454 source, and second and third input are displacement maps.
5456 The second input specifies how much to displace pixels along the
5457 x-axis, while the third input specifies how much to displace pixels
5459 If one of displacement map streams terminates, last frame from that
5460 displacement map will be used.
5462 Note that once generated, displacements maps can be reused over and over again.
5464 A description of the accepted options follows.
5468 Set displace behavior for pixels that are out of range.
5470 Available values are:
5473 Missing pixels are replaced by black pixels.
5476 Adjacent pixels will spread out to replace missing pixels.
5479 Out of range pixels are wrapped so they point to pixels of other side.
5481 Default is @samp{smear}.
5485 @subsection Examples
5489 Add ripple effect to rgb input of video size hd720:
5491 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
5495 Add wave effect to rgb input of video size hd720:
5497 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
5503 Draw a colored box on the input image.
5505 It accepts the following parameters:
5510 The expressions which specify the top left corner coordinates of the box. It defaults to 0.
5514 The expressions which specify the width and height of the box; if 0 they are interpreted as
5515 the input width and height. It defaults to 0.
5518 Specify the color of the box to write. For the general syntax of this option,
5519 check the "Color" section in the ffmpeg-utils manual. If the special
5520 value @code{invert} is used, the box edge color is the same as the
5521 video with inverted luma.
5524 The expression which sets the thickness of the box edge. Default value is @code{3}.
5526 See below for the list of accepted constants.
5529 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
5530 following constants:
5534 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
5538 horizontal and vertical chroma subsample values. For example for the
5539 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5543 The input width and height.
5546 The input sample aspect ratio.
5550 The x and y offset coordinates where the box is drawn.
5554 The width and height of the drawn box.
5557 The thickness of the drawn box.
5559 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
5560 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
5564 @subsection Examples
5568 Draw a black box around the edge of the input image:
5574 Draw a box with color red and an opacity of 50%:
5576 drawbox=10:20:200:60:red@@0.5
5579 The previous example can be specified as:
5581 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
5585 Fill the box with pink color:
5587 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
5591 Draw a 2-pixel red 2.40:1 mask:
5593 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
5597 @section drawgraph, adrawgraph
5599 Draw a graph using input video or audio metadata.
5601 It accepts the following parameters:
5605 Set 1st frame metadata key from which metadata values will be used to draw a graph.
5608 Set 1st foreground color expression.
5611 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
5614 Set 2nd foreground color expression.
5617 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
5620 Set 3rd foreground color expression.
5623 Set 4th frame metadata key from which metadata values will be used to draw a graph.
5626 Set 4th foreground color expression.
5629 Set minimal value of metadata value.
5632 Set maximal value of metadata value.
5635 Set graph background color. Default is white.
5640 Available values for mode is:
5647 Default is @code{line}.
5652 Available values for slide is:
5655 Draw new frame when right border is reached.
5658 Replace old columns with new ones.
5661 Scroll from right to left.
5664 Scroll from left to right.
5667 Default is @code{frame}.
5670 Set size of graph video. For the syntax of this option, check the
5671 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
5672 The default value is @code{900x256}.
5674 The foreground color expressions can use the following variables:
5677 Minimal value of metadata value.
5680 Maximal value of metadata value.
5683 Current metadata key value.
5686 The color is defined as 0xAABBGGRR.
5689 Example using metadata from @ref{signalstats} filter:
5691 signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
5694 Example using metadata from @ref{ebur128} filter:
5696 ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
5701 Draw a grid on the input image.
5703 It accepts the following parameters:
5708 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
5712 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
5713 input width and height, respectively, minus @code{thickness}, so image gets
5714 framed. Default to 0.
5717 Specify the color of the grid. For the general syntax of this option,
5718 check the "Color" section in the ffmpeg-utils manual. If the special
5719 value @code{invert} is used, the grid color is the same as the
5720 video with inverted luma.
5723 The expression which sets the thickness of the grid line. Default value is @code{1}.
5725 See below for the list of accepted constants.
5728 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
5729 following constants:
5733 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
5737 horizontal and vertical chroma subsample values. For example for the
5738 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5742 The input grid cell width and height.
5745 The input sample aspect ratio.
5749 The x and y coordinates of some point of grid intersection (meant to configure offset).
5753 The width and height of the drawn cell.
5756 The thickness of the drawn cell.
5758 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
5759 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
5763 @subsection Examples
5767 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
5769 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
5773 Draw a white 3x3 grid with an opacity of 50%:
5775 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
5782 Draw a text string or text from a specified file on top of a video, using the
5783 libfreetype library.
5785 To enable compilation of this filter, you need to configure FFmpeg with
5786 @code{--enable-libfreetype}.
5787 To enable default font fallback and the @var{font} option you need to
5788 configure FFmpeg with @code{--enable-libfontconfig}.
5789 To enable the @var{text_shaping} option, you need to configure FFmpeg with
5790 @code{--enable-libfribidi}.
5794 It accepts the following parameters:
5799 Used to draw a box around text using the background color.
5800 The value must be either 1 (enable) or 0 (disable).
5801 The default value of @var{box} is 0.
5804 Set the width of the border to be drawn around the box using @var{boxcolor}.
5805 The default value of @var{boxborderw} is 0.
5808 The color to be used for drawing box around text. For the syntax of this
5809 option, check the "Color" section in the ffmpeg-utils manual.
5811 The default value of @var{boxcolor} is "white".
5814 Set the width of the border to be drawn around the text using @var{bordercolor}.
5815 The default value of @var{borderw} is 0.
5818 Set the color to be used for drawing border around text. For the syntax of this
5819 option, check the "Color" section in the ffmpeg-utils manual.
5821 The default value of @var{bordercolor} is "black".
5824 Select how the @var{text} is expanded. Can be either @code{none},
5825 @code{strftime} (deprecated) or
5826 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
5830 If true, check and fix text coords to avoid clipping.
5833 The color to be used for drawing fonts. For the syntax of this option, check
5834 the "Color" section in the ffmpeg-utils manual.
5836 The default value of @var{fontcolor} is "black".
5838 @item fontcolor_expr
5839 String which is expanded the same way as @var{text} to obtain dynamic
5840 @var{fontcolor} value. By default this option has empty value and is not
5841 processed. When this option is set, it overrides @var{fontcolor} option.
5844 The font family to be used for drawing text. By default Sans.
5847 The font file to be used for drawing text. The path must be included.
5848 This parameter is mandatory if the fontconfig support is disabled.
5851 This option does not exist, please see the timeline system
5854 Draw the text applying alpha blending. The value can
5855 be either a number between 0.0 and 1.0
5856 The expression accepts the same variables @var{x, y} do.
5857 The default value is 1.
5858 Please see fontcolor_expr
5861 The font size to be used for drawing text.
5862 The default value of @var{fontsize} is 16.
5865 If set to 1, attempt to shape the text (for example, reverse the order of
5866 right-to-left text and join Arabic characters) before drawing it.
5867 Otherwise, just draw the text exactly as given.
5868 By default 1 (if supported).
5871 The flags to be used for loading the fonts.
5873 The flags map the corresponding flags supported by libfreetype, and are
5874 a combination of the following values:
5881 @item vertical_layout
5882 @item force_autohint
5885 @item ignore_global_advance_width
5887 @item ignore_transform
5893 Default value is "default".
5895 For more information consult the documentation for the FT_LOAD_*
5899 The color to be used for drawing a shadow behind the drawn text. For the
5900 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
5902 The default value of @var{shadowcolor} is "black".
5906 The x and y offsets for the text shadow position with respect to the
5907 position of the text. They can be either positive or negative
5908 values. The default value for both is "0".
5911 The starting frame number for the n/frame_num variable. The default value
5915 The size in number of spaces to use for rendering the tab.
5919 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
5920 format. It can be used with or without text parameter. @var{timecode_rate}
5921 option must be specified.
5923 @item timecode_rate, rate, r
5924 Set the timecode frame rate (timecode only).
5927 The text string to be drawn. The text must be a sequence of UTF-8
5929 This parameter is mandatory if no file is specified with the parameter
5933 A text file containing text to be drawn. The text must be a sequence
5934 of UTF-8 encoded characters.
5936 This parameter is mandatory if no text string is specified with the
5937 parameter @var{text}.
5939 If both @var{text} and @var{textfile} are specified, an error is thrown.
5942 If set to 1, the @var{textfile} will be reloaded before each frame.
5943 Be sure to update it atomically, or it may be read partially, or even fail.
5947 The expressions which specify the offsets where text will be drawn
5948 within the video frame. They are relative to the top/left border of the
5951 The default value of @var{x} and @var{y} is "0".
5953 See below for the list of accepted constants and functions.
5956 The parameters for @var{x} and @var{y} are expressions containing the
5957 following constants and functions:
5961 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
5965 horizontal and vertical chroma subsample values. For example for the
5966 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5969 the height of each text line
5977 @item max_glyph_a, ascent
5978 the maximum distance from the baseline to the highest/upper grid
5979 coordinate used to place a glyph outline point, for all the rendered
5981 It is a positive value, due to the grid's orientation with the Y axis
5984 @item max_glyph_d, descent
5985 the maximum distance from the baseline to the lowest grid coordinate
5986 used to place a glyph outline point, for all the rendered glyphs.
5987 This is a negative value, due to the grid's orientation, with the Y axis
5991 maximum glyph height, that is the maximum height for all the glyphs
5992 contained in the rendered text, it is equivalent to @var{ascent} -
5996 maximum glyph width, that is the maximum width for all the glyphs
5997 contained in the rendered text
6000 the number of input frame, starting from 0
6002 @item rand(min, max)
6003 return a random number included between @var{min} and @var{max}
6006 The input sample aspect ratio.
6009 timestamp expressed in seconds, NAN if the input timestamp is unknown
6012 the height of the rendered text
6015 the width of the rendered text
6019 the x and y offset coordinates where the text is drawn.
6021 These parameters allow the @var{x} and @var{y} expressions to refer
6022 each other, so you can for example specify @code{y=x/dar}.
6025 @anchor{drawtext_expansion}
6026 @subsection Text expansion
6028 If @option{expansion} is set to @code{strftime},
6029 the filter recognizes strftime() sequences in the provided text and
6030 expands them accordingly. Check the documentation of strftime(). This
6031 feature is deprecated.
6033 If @option{expansion} is set to @code{none}, the text is printed verbatim.
6035 If @option{expansion} is set to @code{normal} (which is the default),
6036 the following expansion mechanism is used.
6038 The backslash character @samp{\}, followed by any character, always expands to
6039 the second character.
6041 Sequence of the form @code{%@{...@}} are expanded. The text between the
6042 braces is a function name, possibly followed by arguments separated by ':'.
6043 If the arguments contain special characters or delimiters (':' or '@}'),
6044 they should be escaped.
6046 Note that they probably must also be escaped as the value for the
6047 @option{text} option in the filter argument string and as the filter
6048 argument in the filtergraph description, and possibly also for the shell,
6049 that makes up to four levels of escaping; using a text file avoids these
6052 The following functions are available:
6057 The expression evaluation result.
6059 It must take one argument specifying the expression to be evaluated,
6060 which accepts the same constants and functions as the @var{x} and
6061 @var{y} values. Note that not all constants should be used, for
6062 example the text size is not known when evaluating the expression, so
6063 the constants @var{text_w} and @var{text_h} will have an undefined
6066 @item expr_int_format, eif
6067 Evaluate the expression's value and output as formatted integer.
6069 The first argument is the expression to be evaluated, just as for the @var{expr} function.
6070 The second argument specifies the output format. Allowed values are @samp{x},
6071 @samp{X}, @samp{d} and @samp{u}. They are treated exactly as in the
6072 @code{printf} function.
6073 The third parameter is optional and sets the number of positions taken by the output.
6074 It can be used to add padding with zeros from the left.
6077 The time at which the filter is running, expressed in UTC.
6078 It can accept an argument: a strftime() format string.
6081 The time at which the filter is running, expressed in the local time zone.
6082 It can accept an argument: a strftime() format string.
6085 Frame metadata. It must take one argument specifying metadata key.
6088 The frame number, starting from 0.
6091 A 1 character description of the current picture type.
6094 The timestamp of the current frame.
6095 It can take up to three arguments.
6097 The first argument is the format of the timestamp; it defaults to @code{flt}
6098 for seconds as a decimal number with microsecond accuracy; @code{hms} stands
6099 for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy.
6100 @code{gmtime} stands for the timestamp of the frame formatted as UTC time;
6101 @code{localtime} stands for the timestamp of the frame formatted as
6102 local time zone time.
6104 The second argument is an offset added to the timestamp.
6106 If the format is set to @code{localtime} or @code{gmtime},
6107 a third argument may be supplied: a strftime() format string.
6108 By default, @var{YYYY-MM-DD HH:MM:SS} format will be used.
6111 @subsection Examples
6115 Draw "Test Text" with font FreeSerif, using the default values for the
6116 optional parameters.
6119 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
6123 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
6124 and y=50 (counting from the top-left corner of the screen), text is
6125 yellow with a red box around it. Both the text and the box have an
6129 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
6130 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
6133 Note that the double quotes are not necessary if spaces are not used
6134 within the parameter list.
6137 Show the text at the center of the video frame:
6139 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2"
6143 Show a text line sliding from right to left in the last row of the video
6144 frame. The file @file{LONG_LINE} is assumed to contain a single line
6147 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
6151 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
6153 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
6157 Draw a single green letter "g", at the center of the input video.
6158 The glyph baseline is placed at half screen height.
6160 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
6164 Show text for 1 second every 3 seconds:
6166 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
6170 Use fontconfig to set the font. Note that the colons need to be escaped.
6172 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
6176 Print the date of a real-time encoding (see strftime(3)):
6178 drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}'
6182 Show text fading in and out (appearing/disappearing):
6185 DS=1.0 # display start
6186 DE=10.0 # display end
6187 FID=1.5 # fade in duration
6188 FOD=5 # fade out duration
6189 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 @}"
6194 For more information about libfreetype, check:
6195 @url{http://www.freetype.org/}.
6197 For more information about fontconfig, check:
6198 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
6200 For more information about libfribidi, check:
6201 @url{http://fribidi.org/}.
6205 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
6207 The filter accepts the following options:
6212 Set low and high threshold values used by the Canny thresholding
6215 The high threshold selects the "strong" edge pixels, which are then
6216 connected through 8-connectivity with the "weak" edge pixels selected
6217 by the low threshold.
6219 @var{low} and @var{high} threshold values must be chosen in the range
6220 [0,1], and @var{low} should be lesser or equal to @var{high}.
6222 Default value for @var{low} is @code{20/255}, and default value for @var{high}
6226 Define the drawing mode.
6230 Draw white/gray wires on black background.
6233 Mix the colors to create a paint/cartoon effect.
6236 Default value is @var{wires}.
6239 @subsection Examples
6243 Standard edge detection with custom values for the hysteresis thresholding:
6245 edgedetect=low=0.1:high=0.4
6249 Painting effect without thresholding:
6251 edgedetect=mode=colormix:high=0
6256 Set brightness, contrast, saturation and approximate gamma adjustment.
6258 The filter accepts the following options:
6262 Set the contrast expression. The value must be a float value in range
6263 @code{-2.0} to @code{2.0}. The default value is "1".
6266 Set the brightness expression. The value must be a float value in
6267 range @code{-1.0} to @code{1.0}. The default value is "0".
6270 Set the saturation expression. The value must be a float in
6271 range @code{0.0} to @code{3.0}. The default value is "1".
6274 Set the gamma expression. The value must be a float in range
6275 @code{0.1} to @code{10.0}. The default value is "1".
6278 Set the gamma expression for red. The value must be a float in
6279 range @code{0.1} to @code{10.0}. The default value is "1".
6282 Set the gamma expression for green. The value must be a float in range
6283 @code{0.1} to @code{10.0}. The default value is "1".
6286 Set the gamma expression for blue. The value must be a float in range
6287 @code{0.1} to @code{10.0}. The default value is "1".
6290 Set the gamma weight expression. It can be used to reduce the effect
6291 of a high gamma value on bright image areas, e.g. keep them from
6292 getting overamplified and just plain white. The value must be a float
6293 in range @code{0.0} to @code{1.0}. A value of @code{0.0} turns the
6294 gamma correction all the way down while @code{1.0} leaves it at its
6295 full strength. Default is "1".
6298 Set when the expressions for brightness, contrast, saturation and
6299 gamma expressions are evaluated.
6301 It accepts the following values:
6304 only evaluate expressions once during the filter initialization or
6305 when a command is processed
6308 evaluate expressions for each incoming frame
6311 Default value is @samp{init}.
6314 The expressions accept the following parameters:
6317 frame count of the input frame starting from 0
6320 byte position of the corresponding packet in the input file, NAN if
6324 frame rate of the input video, NAN if the input frame rate is unknown
6327 timestamp expressed in seconds, NAN if the input timestamp is unknown
6330 @subsection Commands
6331 The filter supports the following commands:
6335 Set the contrast expression.
6338 Set the brightness expression.
6341 Set the saturation expression.
6344 Set the gamma expression.
6347 Set the gamma_r expression.
6350 Set gamma_g expression.
6353 Set gamma_b expression.
6356 Set gamma_weight expression.
6358 The command accepts the same syntax of the corresponding option.
6360 If the specified expression is not valid, it is kept at its current
6367 Apply erosion effect to the video.
6369 This filter replaces the pixel by the local(3x3) minimum.
6371 It accepts the following options:
6378 Limit the maximum change for each plane, default is 65535.
6379 If 0, plane will remain unchanged.
6382 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
6385 Flags to local 3x3 coordinates maps like this:
6392 @section extractplanes
6394 Extract color channel components from input video stream into
6395 separate grayscale video streams.
6397 The filter accepts the following option:
6401 Set plane(s) to extract.
6403 Available values for planes are:
6414 Choosing planes not available in the input will result in an error.
6415 That means you cannot select @code{r}, @code{g}, @code{b} planes
6416 with @code{y}, @code{u}, @code{v} planes at same time.
6419 @subsection Examples
6423 Extract luma, u and v color channel component from input video frame
6424 into 3 grayscale outputs:
6426 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
6432 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
6434 For each input image, the filter will compute the optimal mapping from
6435 the input to the output given the codebook length, that is the number
6436 of distinct output colors.
6438 This filter accepts the following options.
6441 @item codebook_length, l
6442 Set codebook length. The value must be a positive integer, and
6443 represents the number of distinct output colors. Default value is 256.
6446 Set the maximum number of iterations to apply for computing the optimal
6447 mapping. The higher the value the better the result and the higher the
6448 computation time. Default value is 1.
6451 Set a random seed, must be an integer included between 0 and
6452 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
6453 will try to use a good random seed on a best effort basis.
6456 Set pal8 output pixel format. This option does not work with codebook
6457 length greater than 256.
6462 Apply a fade-in/out effect to the input video.
6464 It accepts the following parameters:
6468 The effect type can be either "in" for a fade-in, or "out" for a fade-out
6470 Default is @code{in}.
6472 @item start_frame, s
6473 Specify the number of the frame to start applying the fade
6474 effect at. Default is 0.
6477 The number of frames that the fade effect lasts. At the end of the
6478 fade-in effect, the output video will have the same intensity as the input video.
6479 At the end of the fade-out transition, the output video will be filled with the
6480 selected @option{color}.
6484 If set to 1, fade only alpha channel, if one exists on the input.
6487 @item start_time, st
6488 Specify the timestamp (in seconds) of the frame to start to apply the fade
6489 effect. If both start_frame and start_time are specified, the fade will start at
6490 whichever comes last. Default is 0.
6493 The number of seconds for which the fade effect has to last. At the end of the
6494 fade-in effect the output video will have the same intensity as the input video,
6495 at the end of the fade-out transition the output video will be filled with the
6496 selected @option{color}.
6497 If both duration and nb_frames are specified, duration is used. Default is 0
6498 (nb_frames is used by default).
6501 Specify the color of the fade. Default is "black".
6504 @subsection Examples
6508 Fade in the first 30 frames of video:
6513 The command above is equivalent to:
6519 Fade out the last 45 frames of a 200-frame video:
6522 fade=type=out:start_frame=155:nb_frames=45
6526 Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
6528 fade=in:0:25, fade=out:975:25
6532 Make the first 5 frames yellow, then fade in from frame 5-24:
6534 fade=in:5:20:color=yellow
6538 Fade in alpha over first 25 frames of video:
6540 fade=in:0:25:alpha=1
6544 Make the first 5.5 seconds black, then fade in for 0.5 seconds:
6546 fade=t=in:st=5.5:d=0.5
6552 Apply arbitrary expressions to samples in frequency domain
6556 Adjust the dc value (gain) of the luma plane of the image. The filter
6557 accepts an integer value in range @code{0} to @code{1000}. The default
6558 value is set to @code{0}.
6561 Adjust the dc value (gain) of the 1st chroma plane of the image. The
6562 filter accepts an integer value in range @code{0} to @code{1000}. The
6563 default value is set to @code{0}.
6566 Adjust the dc value (gain) of the 2nd chroma plane of the image. The
6567 filter accepts an integer value in range @code{0} to @code{1000}. The
6568 default value is set to @code{0}.
6571 Set the frequency domain weight expression for the luma plane.
6574 Set the frequency domain weight expression for the 1st chroma plane.
6577 Set the frequency domain weight expression for the 2nd chroma plane.
6579 The filter accepts the following variables:
6582 The coordinates of the current sample.
6586 The width and height of the image.
6589 @subsection Examples
6595 fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
6601 fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
6607 fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
6613 fftfilt=dc_Y=0:weight_Y='exp(-4 * ((Y+X)/(W+H)))'
6620 Extract a single field from an interlaced image using stride
6621 arithmetic to avoid wasting CPU time. The output frames are marked as
6624 The filter accepts the following options:
6628 Specify whether to extract the top (if the value is @code{0} or
6629 @code{top}) or the bottom field (if the value is @code{1} or
6635 Field matching filter for inverse telecine. It is meant to reconstruct the
6636 progressive frames from a telecined stream. The filter does not drop duplicated
6637 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
6638 followed by a decimation filter such as @ref{decimate} in the filtergraph.
6640 The separation of the field matching and the decimation is notably motivated by
6641 the possibility of inserting a de-interlacing filter fallback between the two.
6642 If the source has mixed telecined and real interlaced content,
6643 @code{fieldmatch} will not be able to match fields for the interlaced parts.
6644 But these remaining combed frames will be marked as interlaced, and thus can be
6645 de-interlaced by a later filter such as @ref{yadif} before decimation.
6647 In addition to the various configuration options, @code{fieldmatch} can take an
6648 optional second stream, activated through the @option{ppsrc} option. If
6649 enabled, the frames reconstruction will be based on the fields and frames from
6650 this second stream. This allows the first input to be pre-processed in order to
6651 help the various algorithms of the filter, while keeping the output lossless
6652 (assuming the fields are matched properly). Typically, a field-aware denoiser,
6653 or brightness/contrast adjustments can help.
6655 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
6656 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
6657 which @code{fieldmatch} is based on. While the semantic and usage are very
6658 close, some behaviour and options names can differ.
6660 The @ref{decimate} filter currently only works for constant frame rate input.
6661 If your input has mixed telecined (30fps) and progressive content with a lower
6662 framerate like 24fps use the following filterchain to produce the necessary cfr
6663 stream: @code{dejudder,fps=30000/1001,fieldmatch,decimate}.
6665 The filter accepts the following options:
6669 Specify the assumed field order of the input stream. Available values are:
6673 Auto detect parity (use FFmpeg's internal parity value).
6675 Assume bottom field first.
6677 Assume top field first.
6680 Note that it is sometimes recommended not to trust the parity announced by the
6683 Default value is @var{auto}.
6686 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
6687 sense that it won't risk creating jerkiness due to duplicate frames when
6688 possible, but if there are bad edits or blended fields it will end up
6689 outputting combed frames when a good match might actually exist. On the other
6690 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
6691 but will almost always find a good frame if there is one. The other values are
6692 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
6693 jerkiness and creating duplicate frames versus finding good matches in sections
6694 with bad edits, orphaned fields, blended fields, etc.
6696 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
6698 Available values are:
6702 2-way matching (p/c)
6704 2-way matching, and trying 3rd match if still combed (p/c + n)
6706 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
6708 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
6709 still combed (p/c + n + u/b)
6711 3-way matching (p/c/n)
6713 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
6714 detected as combed (p/c/n + u/b)
6717 The parenthesis at the end indicate the matches that would be used for that
6718 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
6721 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
6724 Default value is @var{pc_n}.
6727 Mark the main input stream as a pre-processed input, and enable the secondary
6728 input stream as the clean source to pick the fields from. See the filter
6729 introduction for more details. It is similar to the @option{clip2} feature from
6732 Default value is @code{0} (disabled).
6735 Set the field to match from. It is recommended to set this to the same value as
6736 @option{order} unless you experience matching failures with that setting. In
6737 certain circumstances changing the field that is used to match from can have a
6738 large impact on matching performance. Available values are:
6742 Automatic (same value as @option{order}).
6744 Match from the bottom field.
6746 Match from the top field.
6749 Default value is @var{auto}.
6752 Set whether or not chroma is included during the match comparisons. In most
6753 cases it is recommended to leave this enabled. You should set this to @code{0}
6754 only if your clip has bad chroma problems such as heavy rainbowing or other
6755 artifacts. Setting this to @code{0} could also be used to speed things up at
6756 the cost of some accuracy.
6758 Default value is @code{1}.
6762 These define an exclusion band which excludes the lines between @option{y0} and
6763 @option{y1} from being included in the field matching decision. An exclusion
6764 band can be used to ignore subtitles, a logo, or other things that may
6765 interfere with the matching. @option{y0} sets the starting scan line and
6766 @option{y1} sets the ending line; all lines in between @option{y0} and
6767 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
6768 @option{y0} and @option{y1} to the same value will disable the feature.
6769 @option{y0} and @option{y1} defaults to @code{0}.
6772 Set the scene change detection threshold as a percentage of maximum change on
6773 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
6774 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
6775 @option{scthresh} is @code{[0.0, 100.0]}.
6777 Default value is @code{12.0}.
6780 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
6781 account the combed scores of matches when deciding what match to use as the
6782 final match. Available values are:
6786 No final matching based on combed scores.
6788 Combed scores are only used when a scene change is detected.
6790 Use combed scores all the time.
6793 Default is @var{sc}.
6796 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
6797 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
6798 Available values are:
6802 No forced calculation.
6804 Force p/c/n calculations.
6806 Force p/c/n/u/b calculations.
6809 Default value is @var{none}.
6812 This is the area combing threshold used for combed frame detection. This
6813 essentially controls how "strong" or "visible" combing must be to be detected.
6814 Larger values mean combing must be more visible and smaller values mean combing
6815 can be less visible or strong and still be detected. Valid settings are from
6816 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
6817 be detected as combed). This is basically a pixel difference value. A good
6818 range is @code{[8, 12]}.
6820 Default value is @code{9}.
6823 Sets whether or not chroma is considered in the combed frame decision. Only
6824 disable this if your source has chroma problems (rainbowing, etc.) that are
6825 causing problems for the combed frame detection with chroma enabled. Actually,
6826 using @option{chroma}=@var{0} is usually more reliable, except for the case
6827 where there is chroma only combing in the source.
6829 Default value is @code{0}.
6833 Respectively set the x-axis and y-axis size of the window used during combed
6834 frame detection. This has to do with the size of the area in which
6835 @option{combpel} pixels are required to be detected as combed for a frame to be
6836 declared combed. See the @option{combpel} parameter description for more info.
6837 Possible values are any number that is a power of 2 starting at 4 and going up
6840 Default value is @code{16}.
6843 The number of combed pixels inside any of the @option{blocky} by
6844 @option{blockx} size blocks on the frame for the frame to be detected as
6845 combed. While @option{cthresh} controls how "visible" the combing must be, this
6846 setting controls "how much" combing there must be in any localized area (a
6847 window defined by the @option{blockx} and @option{blocky} settings) on the
6848 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
6849 which point no frames will ever be detected as combed). This setting is known
6850 as @option{MI} in TFM/VFM vocabulary.
6852 Default value is @code{80}.
6855 @anchor{p/c/n/u/b meaning}
6856 @subsection p/c/n/u/b meaning
6858 @subsubsection p/c/n
6860 We assume the following telecined stream:
6863 Top fields: 1 2 2 3 4
6864 Bottom fields: 1 2 3 4 4
6867 The numbers correspond to the progressive frame the fields relate to. Here, the
6868 first two frames are progressive, the 3rd and 4th are combed, and so on.
6870 When @code{fieldmatch} is configured to run a matching from bottom
6871 (@option{field}=@var{bottom}) this is how this input stream get transformed:
6876 B 1 2 3 4 4 <-- matching reference
6885 As a result of the field matching, we can see that some frames get duplicated.
6886 To perform a complete inverse telecine, you need to rely on a decimation filter
6887 after this operation. See for instance the @ref{decimate} filter.
6889 The same operation now matching from top fields (@option{field}=@var{top})
6894 T 1 2 2 3 4 <-- matching reference
6904 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
6905 basically, they refer to the frame and field of the opposite parity:
6908 @item @var{p} matches the field of the opposite parity in the previous frame
6909 @item @var{c} matches the field of the opposite parity in the current frame
6910 @item @var{n} matches the field of the opposite parity in the next frame
6915 The @var{u} and @var{b} matching are a bit special in the sense that they match
6916 from the opposite parity flag. In the following examples, we assume that we are
6917 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
6918 'x' is placed above and below each matched fields.
6920 With bottom matching (@option{field}=@var{bottom}):
6925 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6926 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6934 With top matching (@option{field}=@var{top}):
6939 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6940 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6948 @subsection Examples
6950 Simple IVTC of a top field first telecined stream:
6952 fieldmatch=order=tff:combmatch=none, decimate
6955 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
6957 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
6962 Transform the field order of the input video.
6964 It accepts the following parameters:
6969 The output field order. Valid values are @var{tff} for top field first or @var{bff}
6970 for bottom field first.
6973 The default value is @samp{tff}.
6975 The transformation is done by shifting the picture content up or down
6976 by one line, and filling the remaining line with appropriate picture content.
6977 This method is consistent with most broadcast field order converters.
6979 If the input video is not flagged as being interlaced, or it is already
6980 flagged as being of the required output field order, then this filter does
6981 not alter the incoming video.
6983 It is very useful when converting to or from PAL DV material,
6984 which is bottom field first.
6988 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
6991 @section fifo, afifo
6993 Buffer input images and send them when they are requested.
6995 It is mainly useful when auto-inserted by the libavfilter
6998 It does not take parameters.
7002 Find a rectangular object
7004 It accepts the following options:
7008 Filepath of the object image, needs to be in gray8.
7011 Detection threshold, default is 0.5.
7014 Number of mipmaps, default is 3.
7016 @item xmin, ymin, xmax, ymax
7017 Specifies the rectangle in which to search.
7020 @subsection Examples
7024 Generate a representative palette of a given video using @command{ffmpeg}:
7026 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
7032 Cover a rectangular object
7034 It accepts the following options:
7038 Filepath of the optional cover image, needs to be in yuv420.
7043 It accepts the following values:
7046 cover it by the supplied image
7048 cover it by interpolating the surrounding pixels
7051 Default value is @var{blur}.
7054 @subsection Examples
7058 Generate a representative palette of a given video using @command{ffmpeg}:
7060 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
7067 Convert the input video to one of the specified pixel formats.
7068 Libavfilter will try to pick one that is suitable as input to
7071 It accepts the following parameters:
7075 A '|'-separated list of pixel format names, such as
7076 "pix_fmts=yuv420p|monow|rgb24".
7080 @subsection Examples
7084 Convert the input video to the @var{yuv420p} format
7086 format=pix_fmts=yuv420p
7089 Convert the input video to any of the formats in the list
7091 format=pix_fmts=yuv420p|yuv444p|yuv410p
7098 Convert the video to specified constant frame rate by duplicating or dropping
7099 frames as necessary.
7101 It accepts the following parameters:
7105 The desired output frame rate. The default is @code{25}.
7110 Possible values are:
7113 zero round towards 0
7117 round towards -infinity
7119 round towards +infinity
7123 The default is @code{near}.
7126 Assume the first PTS should be the given value, in seconds. This allows for
7127 padding/trimming at the start of stream. By default, no assumption is made
7128 about the first frame's expected PTS, so no padding or trimming is done.
7129 For example, this could be set to 0 to pad the beginning with duplicates of
7130 the first frame if a video stream starts after the audio stream or to trim any
7131 frames with a negative PTS.
7135 Alternatively, the options can be specified as a flat string:
7136 @var{fps}[:@var{round}].
7138 See also the @ref{setpts} filter.
7140 @subsection Examples
7144 A typical usage in order to set the fps to 25:
7150 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
7152 fps=fps=film:round=near
7158 Pack two different video streams into a stereoscopic video, setting proper
7159 metadata on supported codecs. The two views should have the same size and
7160 framerate and processing will stop when the shorter video ends. Please note
7161 that you may conveniently adjust view properties with the @ref{scale} and
7164 It accepts the following parameters:
7168 The desired packing format. Supported values are:
7173 The views are next to each other (default).
7176 The views are on top of each other.
7179 The views are packed by line.
7182 The views are packed by column.
7185 The views are temporally interleaved.
7194 # Convert left and right views into a frame-sequential video
7195 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
7197 # Convert views into a side-by-side video with the same output resolution as the input
7198 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
7203 Change the frame rate by interpolating new video output frames from the source
7206 This filter is not designed to function correctly with interlaced media. If
7207 you wish to change the frame rate of interlaced media then you are required
7208 to deinterlace before this filter and re-interlace after this filter.
7210 A description of the accepted options follows.
7214 Specify the output frames per second. This option can also be specified
7215 as a value alone. The default is @code{50}.
7218 Specify the start of a range where the output frame will be created as a
7219 linear interpolation of two frames. The range is [@code{0}-@code{255}],
7220 the default is @code{15}.
7223 Specify the end of a range where the output frame will be created as a
7224 linear interpolation of two frames. The range is [@code{0}-@code{255}],
7225 the default is @code{240}.
7228 Specify the level at which a scene change is detected as a value between
7229 0 and 100 to indicate a new scene; a low value reflects a low
7230 probability for the current frame to introduce a new scene, while a higher
7231 value means the current frame is more likely to be one.
7232 The default is @code{7}.
7235 Specify flags influencing the filter process.
7237 Available value for @var{flags} is:
7240 @item scene_change_detect, scd
7241 Enable scene change detection using the value of the option @var{scene}.
7242 This flag is enabled by default.
7248 Select one frame every N-th frame.
7250 This filter accepts the following option:
7253 Select frame after every @code{step} frames.
7254 Allowed values are positive integers higher than 0. Default value is @code{1}.
7260 Apply a frei0r effect to the input video.
7262 To enable the compilation of this filter, you need to install the frei0r
7263 header and configure FFmpeg with @code{--enable-frei0r}.
7265 It accepts the following parameters:
7270 The name of the frei0r effect to load. If the environment variable
7271 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
7272 directories specified by the colon-separated list in @env{FREIOR_PATH}.
7273 Otherwise, the standard frei0r paths are searched, in this order:
7274 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
7275 @file{/usr/lib/frei0r-1/}.
7278 A '|'-separated list of parameters to pass to the frei0r effect.
7282 A frei0r effect parameter can be a boolean (its value is either
7283 "y" or "n"), a double, a color (specified as
7284 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
7285 numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
7286 section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where
7287 @var{X} and @var{Y} are floating point numbers) and/or a string.
7289 The number and types of parameters depend on the loaded effect. If an
7290 effect parameter is not specified, the default value is set.
7292 @subsection Examples
7296 Apply the distort0r effect, setting the first two double parameters:
7298 frei0r=filter_name=distort0r:filter_params=0.5|0.01
7302 Apply the colordistance effect, taking a color as the first parameter:
7304 frei0r=colordistance:0.2/0.3/0.4
7305 frei0r=colordistance:violet
7306 frei0r=colordistance:0x112233
7310 Apply the perspective effect, specifying the top left and top right image
7313 frei0r=perspective:0.2/0.2|0.8/0.2
7317 For more information, see
7318 @url{http://frei0r.dyne.org}
7322 Apply fast and simple postprocessing. It is a faster version of @ref{spp}.
7324 It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
7325 processing filter, one of them is performed once per block, not per pixel.
7326 This allows for much higher speed.
7328 The filter accepts the following options:
7332 Set quality. This option defines the number of levels for averaging. It accepts
7333 an integer in the range 4-5. Default value is @code{4}.
7336 Force a constant quantization parameter. It accepts an integer in range 0-63.
7337 If not set, the filter will use the QP from the video stream (if available).
7340 Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
7341 more details but also more artifacts, while higher values make the image smoother
7342 but also blurrier. Default value is @code{0} − PSNR optimal.
7345 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
7346 option may cause flicker since the B-Frames have often larger QP. Default is
7347 @code{0} (not enabled).
7353 The filter accepts the following options:
7357 Set the luminance expression.
7359 Set the chrominance blue expression.
7361 Set the chrominance red expression.
7363 Set the alpha expression.
7365 Set the red expression.
7367 Set the green expression.
7369 Set the blue expression.
7372 The colorspace is selected according to the specified options. If one
7373 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
7374 options is specified, the filter will automatically select a YCbCr
7375 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
7376 @option{blue_expr} options is specified, it will select an RGB
7379 If one of the chrominance expression is not defined, it falls back on the other
7380 one. If no alpha expression is specified it will evaluate to opaque value.
7381 If none of chrominance expressions are specified, they will evaluate
7382 to the luminance expression.
7384 The expressions can use the following variables and functions:
7388 The sequential number of the filtered frame, starting from @code{0}.
7392 The coordinates of the current sample.
7396 The width and height of the image.
7400 Width and height scale depending on the currently filtered plane. It is the
7401 ratio between the corresponding luma plane number of pixels and the current
7402 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
7403 @code{0.5,0.5} for chroma planes.
7406 Time of the current frame, expressed in seconds.
7409 Return the value of the pixel at location (@var{x},@var{y}) of the current
7413 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
7417 Return the value of the pixel at location (@var{x},@var{y}) of the
7418 blue-difference chroma plane. Return 0 if there is no such plane.
7421 Return the value of the pixel at location (@var{x},@var{y}) of the
7422 red-difference chroma plane. Return 0 if there is no such plane.
7427 Return the value of the pixel at location (@var{x},@var{y}) of the
7428 red/green/blue component. Return 0 if there is no such component.
7431 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
7432 plane. Return 0 if there is no such plane.
7435 For functions, if @var{x} and @var{y} are outside the area, the value will be
7436 automatically clipped to the closer edge.
7438 @subsection Examples
7442 Flip the image horizontally:
7448 Generate a bidimensional sine wave, with angle @code{PI/3} and a
7449 wavelength of 100 pixels:
7451 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
7455 Generate a fancy enigmatic moving light:
7457 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
7461 Generate a quick emboss effect:
7463 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
7467 Modify RGB components depending on pixel position:
7469 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
7473 Create a radial gradient that is the same size as the input (also see
7474 the @ref{vignette} filter):
7476 geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
7480 Create a linear gradient to use as a mask for another filter, then
7481 compose with @ref{overlay}. In this example the video will gradually
7482 become more blurry from the top to the bottom of the y-axis as defined
7483 by the linear gradient:
7485 ffmpeg -i input.mp4 -filter_complex "geq=lum=255*(Y/H),format=gray[grad];[0:v]boxblur=4[blur];[blur][grad]alphamerge[alpha];[0:v][alpha]overlay" output.mp4
7491 Fix the banding artifacts that are sometimes introduced into nearly flat
7492 regions by truncation to 8bit color depth.
7493 Interpolate the gradients that should go where the bands are, and
7496 It is designed for playback only. Do not use it prior to
7497 lossy compression, because compression tends to lose the dither and
7498 bring back the bands.
7500 It accepts the following parameters:
7505 The maximum amount by which the filter will change any one pixel. This is also
7506 the threshold for detecting nearly flat regions. Acceptable values range from
7507 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
7511 The neighborhood to fit the gradient to. A larger radius makes for smoother
7512 gradients, but also prevents the filter from modifying the pixels near detailed
7513 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
7514 values will be clipped to the valid range.
7518 Alternatively, the options can be specified as a flat string:
7519 @var{strength}[:@var{radius}]
7521 @subsection Examples
7525 Apply the filter with a @code{3.5} strength and radius of @code{8}:
7531 Specify radius, omitting the strength (which will fall-back to the default
7542 Apply a Hald CLUT to a video stream.
7544 First input is the video stream to process, and second one is the Hald CLUT.
7545 The Hald CLUT input can be a simple picture or a complete video stream.
7547 The filter accepts the following options:
7551 Force termination when the shortest input terminates. Default is @code{0}.
7553 Continue applying the last CLUT after the end of the stream. A value of
7554 @code{0} disable the filter after the last frame of the CLUT is reached.
7555 Default is @code{1}.
7558 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
7559 filters share the same internals).
7561 More information about the Hald CLUT can be found on Eskil Steenberg's website
7562 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
7564 @subsection Workflow examples
7566 @subsubsection Hald CLUT video stream
7568 Generate an identity Hald CLUT stream altered with various effects:
7570 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
7573 Note: make sure you use a lossless codec.
7575 Then use it with @code{haldclut} to apply it on some random stream:
7577 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
7580 The Hald CLUT will be applied to the 10 first seconds (duration of
7581 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
7582 to the remaining frames of the @code{mandelbrot} stream.
7584 @subsubsection Hald CLUT with preview
7586 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
7587 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
7588 biggest possible square starting at the top left of the picture. The remaining
7589 padding pixels (bottom or right) will be ignored. This area can be used to add
7590 a preview of the Hald CLUT.
7592 Typically, the following generated Hald CLUT will be supported by the
7593 @code{haldclut} filter:
7596 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
7597 pad=iw+320 [padded_clut];
7598 smptebars=s=320x256, split [a][b];
7599 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
7600 [main][b] overlay=W-320" -frames:v 1 clut.png
7603 It contains the original and a preview of the effect of the CLUT: SMPTE color
7604 bars are displayed on the right-top, and below the same color bars processed by
7607 Then, the effect of this Hald CLUT can be visualized with:
7609 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
7614 Flip the input video horizontally.
7616 For example, to horizontally flip the input video with @command{ffmpeg}:
7618 ffmpeg -i in.avi -vf "hflip" out.avi
7622 This filter applies a global color histogram equalization on a
7625 It can be used to correct video that has a compressed range of pixel
7626 intensities. The filter redistributes the pixel intensities to
7627 equalize their distribution across the intensity range. It may be
7628 viewed as an "automatically adjusting contrast filter". This filter is
7629 useful only for correcting degraded or poorly captured source
7632 The filter accepts the following options:
7636 Determine the amount of equalization to be applied. As the strength
7637 is reduced, the distribution of pixel intensities more-and-more
7638 approaches that of the input frame. The value must be a float number
7639 in the range [0,1] and defaults to 0.200.
7642 Set the maximum intensity that can generated and scale the output
7643 values appropriately. The strength should be set as desired and then
7644 the intensity can be limited if needed to avoid washing-out. The value
7645 must be a float number in the range [0,1] and defaults to 0.210.
7648 Set the antibanding level. If enabled the filter will randomly vary
7649 the luminance of output pixels by a small amount to avoid banding of
7650 the histogram. Possible values are @code{none}, @code{weak} or
7651 @code{strong}. It defaults to @code{none}.
7656 Compute and draw a color distribution histogram for the input video.
7658 The computed histogram is a representation of the color component
7659 distribution in an image.
7661 Standard histogram displays the color components distribution in an image.
7662 Displays color graph for each color component. Shows distribution of
7663 the Y, U, V, A or R, G, B components, depending on input format, in the
7664 current frame. Below each graph a color component scale meter is shown.
7666 The filter accepts the following options:
7670 Set height of level. Default value is @code{200}.
7671 Allowed range is [50, 2048].
7674 Set height of color scale. Default value is @code{12}.
7675 Allowed range is [0, 40].
7679 It accepts the following values:
7682 Per color component graphs are placed below each other.
7685 Presents information identical to that in the @code{parade}, except
7686 that the graphs representing color components are superimposed directly
7689 Default is @code{parade}.
7692 Set mode. Can be either @code{linear}, or @code{logarithmic}.
7693 Default is @code{linear}.
7696 Set what color components to display.
7697 Default is @code{7}.
7700 @subsection Examples
7705 Calculate and draw histogram:
7707 ffplay -i input -vf histogram
7715 This is a high precision/quality 3d denoise filter. It aims to reduce
7716 image noise, producing smooth images and making still images really
7717 still. It should enhance compressibility.
7719 It accepts the following optional parameters:
7723 A non-negative floating point number which specifies spatial luma strength.
7726 @item chroma_spatial
7727 A non-negative floating point number which specifies spatial chroma strength.
7728 It defaults to 3.0*@var{luma_spatial}/4.0.
7731 A floating point number which specifies luma temporal strength. It defaults to
7732 6.0*@var{luma_spatial}/4.0.
7735 A floating point number which specifies chroma temporal strength. It defaults to
7736 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
7741 Apply a high-quality magnification filter designed for pixel art. This filter
7742 was originally created by Maxim Stepin.
7744 It accepts the following option:
7748 Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
7749 @code{hq3x} and @code{4} for @code{hq4x}.
7750 Default is @code{3}.
7754 Stack input videos horizontally.
7756 All streams must be of same pixel format and of same height.
7758 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
7759 to create same output.
7761 The filter accept the following option:
7765 Set number of input streams. Default is 2.
7768 If set to 1, force the output to terminate when the shortest input
7769 terminates. Default value is 0.
7774 Modify the hue and/or the saturation of the input.
7776 It accepts the following parameters:
7780 Specify the hue angle as a number of degrees. It accepts an expression,
7781 and defaults to "0".
7784 Specify the saturation in the [-10,10] range. It accepts an expression and
7788 Specify the hue angle as a number of radians. It accepts an
7789 expression, and defaults to "0".
7792 Specify the brightness in the [-10,10] range. It accepts an expression and
7796 @option{h} and @option{H} are mutually exclusive, and can't be
7797 specified at the same time.
7799 The @option{b}, @option{h}, @option{H} and @option{s} option values are
7800 expressions containing the following constants:
7804 frame count of the input frame starting from 0
7807 presentation timestamp of the input frame expressed in time base units
7810 frame rate of the input video, NAN if the input frame rate is unknown
7813 timestamp expressed in seconds, NAN if the input timestamp is unknown
7816 time base of the input video
7819 @subsection Examples
7823 Set the hue to 90 degrees and the saturation to 1.0:
7829 Same command but expressing the hue in radians:
7835 Rotate hue and make the saturation swing between 0
7836 and 2 over a period of 1 second:
7838 hue="H=2*PI*t: s=sin(2*PI*t)+1"
7842 Apply a 3 seconds saturation fade-in effect starting at 0:
7847 The general fade-in expression can be written as:
7849 hue="s=min(0\, max((t-START)/DURATION\, 1))"
7853 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
7855 hue="s=max(0\, min(1\, (8-t)/3))"
7858 The general fade-out expression can be written as:
7860 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
7865 @subsection Commands
7867 This filter supports the following commands:
7873 Modify the hue and/or the saturation and/or brightness of the input video.
7874 The command accepts the same syntax of the corresponding option.
7876 If the specified expression is not valid, it is kept at its current
7882 Detect video interlacing type.
7884 This filter tries to detect if the input frames as interlaced, progressive,
7885 top or bottom field first. It will also try and detect fields that are
7886 repeated between adjacent frames (a sign of telecine).
7888 Single frame detection considers only immediately adjacent frames when classifying each frame.
7889 Multiple frame detection incorporates the classification history of previous frames.
7891 The filter will log these metadata values:
7894 @item single.current_frame
7895 Detected type of current frame using single-frame detection. One of:
7896 ``tff'' (top field first), ``bff'' (bottom field first),
7897 ``progressive'', or ``undetermined''
7900 Cumulative number of frames detected as top field first using single-frame detection.
7903 Cumulative number of frames detected as top field first using multiple-frame detection.
7906 Cumulative number of frames detected as bottom field first using single-frame detection.
7908 @item multiple.current_frame
7909 Detected type of current frame using multiple-frame detection. One of:
7910 ``tff'' (top field first), ``bff'' (bottom field first),
7911 ``progressive'', or ``undetermined''
7914 Cumulative number of frames detected as bottom field first using multiple-frame detection.
7916 @item single.progressive
7917 Cumulative number of frames detected as progressive using single-frame detection.
7919 @item multiple.progressive
7920 Cumulative number of frames detected as progressive using multiple-frame detection.
7922 @item single.undetermined
7923 Cumulative number of frames that could not be classified using single-frame detection.
7925 @item multiple.undetermined
7926 Cumulative number of frames that could not be classified using multiple-frame detection.
7928 @item repeated.current_frame
7929 Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''.
7931 @item repeated.neither
7932 Cumulative number of frames with no repeated field.
7935 Cumulative number of frames with the top field repeated from the previous frame's top field.
7937 @item repeated.bottom
7938 Cumulative number of frames with the bottom field repeated from the previous frame's bottom field.
7941 The filter accepts the following options:
7945 Set interlacing threshold.
7947 Set progressive threshold.
7949 Threshold for repeated field detection.
7951 Number of frames after which a given frame's contribution to the
7952 statistics is halved (i.e., it contributes only 0.5 to it's
7953 classification). The default of 0 means that all frames seen are given
7954 full weight of 1.0 forever.
7955 @item analyze_interlaced_flag
7956 When this is not 0 then idet will use the specified number of frames to determine
7957 if the interlaced flag is accurate, it will not count undetermined frames.
7958 If the flag is found to be accurate it will be used without any further
7959 computations, if it is found to be inaccurate it will be cleared without any
7960 further computations. This allows inserting the idet filter as a low computational
7961 method to clean up the interlaced flag
7966 Deinterleave or interleave fields.
7968 This filter allows one to process interlaced images fields without
7969 deinterlacing them. Deinterleaving splits the input frame into 2
7970 fields (so called half pictures). Odd lines are moved to the top
7971 half of the output image, even lines to the bottom half.
7972 You can process (filter) them independently and then re-interleave them.
7974 The filter accepts the following options:
7978 @item chroma_mode, c
7980 Available values for @var{luma_mode}, @var{chroma_mode} and
7981 @var{alpha_mode} are:
7987 @item deinterleave, d
7988 Deinterleave fields, placing one above the other.
7991 Interleave fields. Reverse the effect of deinterleaving.
7993 Default value is @code{none}.
7996 @item chroma_swap, cs
7997 @item alpha_swap, as
7998 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
8003 Apply inflate effect to the video.
8005 This filter replaces the pixel by the local(3x3) average by taking into account
8006 only values higher than the pixel.
8008 It accepts the following options:
8015 Limit the maximum change for each plane, default is 65535.
8016 If 0, plane will remain unchanged.
8021 Simple interlacing filter from progressive contents. This interleaves upper (or
8022 lower) lines from odd frames with lower (or upper) lines from even frames,
8023 halving the frame rate and preserving image height.
8026 Original Original New Frame
8027 Frame 'j' Frame 'j+1' (tff)
8028 ========== =========== ==================
8029 Line 0 --------------------> Frame 'j' Line 0
8030 Line 1 Line 1 ----> Frame 'j+1' Line 1
8031 Line 2 ---------------------> Frame 'j' Line 2
8032 Line 3 Line 3 ----> Frame 'j+1' Line 3
8034 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
8037 It accepts the following optional parameters:
8041 This determines whether the interlaced frame is taken from the even
8042 (tff - default) or odd (bff) lines of the progressive frame.
8045 Enable (default) or disable the vertical lowpass filter to avoid twitter
8046 interlacing and reduce moire patterns.
8051 Deinterlace input video by applying Donald Graft's adaptive kernel
8052 deinterling. Work on interlaced parts of a video to produce
8055 The description of the accepted parameters follows.
8059 Set the threshold which affects the filter's tolerance when
8060 determining if a pixel line must be processed. It must be an integer
8061 in the range [0,255] and defaults to 10. A value of 0 will result in
8062 applying the process on every pixels.
8065 Paint pixels exceeding the threshold value to white if set to 1.
8069 Set the fields order. Swap fields if set to 1, leave fields alone if
8073 Enable additional sharpening if set to 1. Default is 0.
8076 Enable twoway sharpening if set to 1. Default is 0.
8079 @subsection Examples
8083 Apply default values:
8085 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
8089 Enable additional sharpening:
8095 Paint processed pixels in white:
8101 @section lenscorrection
8103 Correct radial lens distortion
8105 This filter can be used to correct for radial distortion as can result from the use
8106 of wide angle lenses, and thereby re-rectify the image. To find the right parameters
8107 one can use tools available for example as part of opencv or simply trial-and-error.
8108 To use opencv use the calibration sample (under samples/cpp) from the opencv sources
8109 and extract the k1 and k2 coefficients from the resulting matrix.
8111 Note that effectively the same filter is available in the open-source tools Krita and
8112 Digikam from the KDE project.
8114 In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
8115 this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
8116 brightness distribution, so you may want to use both filters together in certain
8117 cases, though you will have to take care of ordering, i.e. whether vignetting should
8118 be applied before or after lens correction.
8122 The filter accepts the following options:
8126 Relative x-coordinate of the focal point of the image, and thereby the center of the
8127 distortion. This value has a range [0,1] and is expressed as fractions of the image
8130 Relative y-coordinate of the focal point of the image, and thereby the center of the
8131 distortion. This value has a range [0,1] and is expressed as fractions of the image
8134 Coefficient of the quadratic correction term. 0.5 means no correction.
8136 Coefficient of the double quadratic correction term. 0.5 means no correction.
8139 The formula that generates the correction is:
8141 @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)
8143 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
8144 distances from the focal point in the source and target images, respectively.
8149 Apply a 3D LUT to an input video.
8151 The filter accepts the following options:
8155 Set the 3D LUT file name.
8157 Currently supported formats:
8169 Select interpolation mode.
8171 Available values are:
8175 Use values from the nearest defined point.
8177 Interpolate values using the 8 points defining a cube.
8179 Interpolate values using a tetrahedron.
8183 @section lut, lutrgb, lutyuv
8185 Compute a look-up table for binding each pixel component input value
8186 to an output value, and apply it to the input video.
8188 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
8189 to an RGB input video.
8191 These filters accept the following parameters:
8194 set first pixel component expression
8196 set second pixel component expression
8198 set third pixel component expression
8200 set fourth pixel component expression, corresponds to the alpha component
8203 set red component expression
8205 set green component expression
8207 set blue component expression
8209 alpha component expression
8212 set Y/luminance component expression
8214 set U/Cb component expression
8216 set V/Cr component expression
8219 Each of them specifies the expression to use for computing the lookup table for
8220 the corresponding pixel component values.
8222 The exact component associated to each of the @var{c*} options depends on the
8225 The @var{lut} filter requires either YUV or RGB pixel formats in input,
8226 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
8228 The expressions can contain the following constants and functions:
8233 The input width and height.
8236 The input value for the pixel component.
8239 The input value, clipped to the @var{minval}-@var{maxval} range.
8242 The maximum value for the pixel component.
8245 The minimum value for the pixel component.
8248 The negated value for the pixel component value, clipped to the
8249 @var{minval}-@var{maxval} range; it corresponds to the expression
8250 "maxval-clipval+minval".
8253 The computed value in @var{val}, clipped to the
8254 @var{minval}-@var{maxval} range.
8256 @item gammaval(gamma)
8257 The computed gamma correction value of the pixel component value,
8258 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
8260 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
8264 All expressions default to "val".
8266 @subsection Examples
8272 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
8273 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
8276 The above is the same as:
8278 lutrgb="r=negval:g=negval:b=negval"
8279 lutyuv="y=negval:u=negval:v=negval"
8289 Remove chroma components, turning the video into a graytone image:
8291 lutyuv="u=128:v=128"
8295 Apply a luma burning effect:
8301 Remove green and blue components:
8307 Set a constant alpha channel value on input:
8309 format=rgba,lutrgb=a="maxval-minval/2"
8313 Correct luminance gamma by a factor of 0.5:
8315 lutyuv=y=gammaval(0.5)
8319 Discard least significant bits of luma:
8321 lutyuv=y='bitand(val, 128+64+32)'
8325 @section maskedmerge
8327 Merge the first input stream with the second input stream using per pixel
8328 weights in the third input stream.
8330 A value of 0 in the third stream pixel component means that pixel component
8331 from first stream is returned unchanged, while maximum value (eg. 255 for
8332 8-bit videos) means that pixel component from second stream is returned
8333 unchanged. Intermediate values define the amount of merging between both
8334 input stream's pixel components.
8336 This filter accepts the following options:
8339 Set which planes will be processed as bitmap, unprocessed planes will be
8340 copied from first stream.
8341 By default value 0xf, all planes will be processed.
8346 Apply motion-compensation deinterlacing.
8348 It needs one field per frame as input and must thus be used together
8349 with yadif=1/3 or equivalent.
8351 This filter accepts the following options:
8354 Set the deinterlacing mode.
8356 It accepts one of the following values:
8361 use iterative motion estimation
8363 like @samp{slow}, but use multiple reference frames.
8365 Default value is @samp{fast}.
8368 Set the picture field parity assumed for the input video. It must be
8369 one of the following values:
8373 assume top field first
8375 assume bottom field first
8378 Default value is @samp{bff}.
8381 Set per-block quantization parameter (QP) used by the internal
8384 Higher values should result in a smoother motion vector field but less
8385 optimal individual vectors. Default value is 1.
8388 @section mergeplanes
8390 Merge color channel components from several video streams.
8392 The filter accepts up to 4 input streams, and merge selected input
8393 planes to the output video.
8395 This filter accepts the following options:
8398 Set input to output plane mapping. Default is @code{0}.
8400 The mappings is specified as a bitmap. It should be specified as a
8401 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
8402 mapping for the first plane of the output stream. 'A' sets the number of
8403 the input stream to use (from 0 to 3), and 'a' the plane number of the
8404 corresponding input to use (from 0 to 3). The rest of the mappings is
8405 similar, 'Bb' describes the mapping for the output stream second
8406 plane, 'Cc' describes the mapping for the output stream third plane and
8407 'Dd' describes the mapping for the output stream fourth plane.
8410 Set output pixel format. Default is @code{yuva444p}.
8413 @subsection Examples
8417 Merge three gray video streams of same width and height into single video stream:
8419 [a0][a1][a2]mergeplanes=0x001020:yuv444p
8423 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
8425 [a0][a1]mergeplanes=0x00010210:yuva444p
8429 Swap Y and A plane in yuva444p stream:
8431 format=yuva444p,mergeplanes=0x03010200:yuva444p
8435 Swap U and V plane in yuv420p stream:
8437 format=yuv420p,mergeplanes=0x000201:yuv420p
8441 Cast a rgb24 clip to yuv444p:
8443 format=rgb24,mergeplanes=0x000102:yuv444p
8449 Drop frames that do not differ greatly from the previous frame in
8450 order to reduce frame rate.
8452 The main use of this filter is for very-low-bitrate encoding
8453 (e.g. streaming over dialup modem), but it could in theory be used for
8454 fixing movies that were inverse-telecined incorrectly.
8456 A description of the accepted options follows.
8460 Set the maximum number of consecutive frames which can be dropped (if
8461 positive), or the minimum interval between dropped frames (if
8462 negative). If the value is 0, the frame is dropped unregarding the
8463 number of previous sequentially dropped frames.
8470 Set the dropping threshold values.
8472 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
8473 represent actual pixel value differences, so a threshold of 64
8474 corresponds to 1 unit of difference for each pixel, or the same spread
8475 out differently over the block.
8477 A frame is a candidate for dropping if no 8x8 blocks differ by more
8478 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
8479 meaning the whole image) differ by more than a threshold of @option{lo}.
8481 Default value for @option{hi} is 64*12, default value for @option{lo} is
8482 64*5, and default value for @option{frac} is 0.33.
8490 It accepts an integer in input; if non-zero it negates the
8491 alpha component (if available). The default value in input is 0.
8495 Force libavfilter not to use any of the specified pixel formats for the
8496 input to the next filter.
8498 It accepts the following parameters:
8502 A '|'-separated list of pixel format names, such as
8503 apix_fmts=yuv420p|monow|rgb24".
8507 @subsection Examples
8511 Force libavfilter to use a format different from @var{yuv420p} for the
8512 input to the vflip filter:
8514 noformat=pix_fmts=yuv420p,vflip
8518 Convert the input video to any of the formats not contained in the list:
8520 noformat=yuv420p|yuv444p|yuv410p
8526 Add noise on video input frame.
8528 The filter accepts the following options:
8536 Set noise seed for specific pixel component or all pixel components in case
8537 of @var{all_seed}. Default value is @code{123457}.
8539 @item all_strength, alls
8540 @item c0_strength, c0s
8541 @item c1_strength, c1s
8542 @item c2_strength, c2s
8543 @item c3_strength, c3s
8544 Set noise strength for specific pixel component or all pixel components in case
8545 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
8547 @item all_flags, allf
8552 Set pixel component flags or set flags for all components if @var{all_flags}.
8553 Available values for component flags are:
8556 averaged temporal noise (smoother)
8558 mix random noise with a (semi)regular pattern
8560 temporal noise (noise pattern changes between frames)
8562 uniform noise (gaussian otherwise)
8566 @subsection Examples
8568 Add temporal and uniform noise to input video:
8570 noise=alls=20:allf=t+u
8575 Pass the video source unchanged to the output.
8578 Optical Character Recognition
8580 This filter uses Tesseract for optical character recognition.
8582 It accepts the following options:
8586 Set datapath to tesseract data. Default is to use whatever was
8587 set at installation.
8590 Set language, default is "eng".
8593 Set character whitelist.
8596 Set character blacklist.
8599 The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
8603 Apply a video transform using libopencv.
8605 To enable this filter, install the libopencv library and headers and
8606 configure FFmpeg with @code{--enable-libopencv}.
8608 It accepts the following parameters:
8613 The name of the libopencv filter to apply.
8616 The parameters to pass to the libopencv filter. If not specified, the default
8621 Refer to the official libopencv documentation for more precise
8623 @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html}
8625 Several libopencv filters are supported; see the following subsections.
8630 Dilate an image by using a specific structuring element.
8631 It corresponds to the libopencv function @code{cvDilate}.
8633 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
8635 @var{struct_el} represents a structuring element, and has the syntax:
8636 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
8638 @var{cols} and @var{rows} represent the number of columns and rows of
8639 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
8640 point, and @var{shape} the shape for the structuring element. @var{shape}
8641 must be "rect", "cross", "ellipse", or "custom".
8643 If the value for @var{shape} is "custom", it must be followed by a
8644 string of the form "=@var{filename}". The file with name
8645 @var{filename} is assumed to represent a binary image, with each
8646 printable character corresponding to a bright pixel. When a custom
8647 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
8648 or columns and rows of the read file are assumed instead.
8650 The default value for @var{struct_el} is "3x3+0x0/rect".
8652 @var{nb_iterations} specifies the number of times the transform is
8653 applied to the image, and defaults to 1.
8657 # Use the default values
8660 # Dilate using a structuring element with a 5x5 cross, iterating two times
8661 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
8663 # Read the shape from the file diamond.shape, iterating two times.
8664 # The file diamond.shape may contain a pattern of characters like this
8670 # The specified columns and rows are ignored
8671 # but the anchor point coordinates are not
8672 ocv=dilate:0x0+2x2/custom=diamond.shape|2
8677 Erode an image by using a specific structuring element.
8678 It corresponds to the libopencv function @code{cvErode}.
8680 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
8681 with the same syntax and semantics as the @ref{dilate} filter.
8685 Smooth the input video.
8687 The filter takes the following parameters:
8688 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
8690 @var{type} is the type of smooth filter to apply, and must be one of
8691 the following values: "blur", "blur_no_scale", "median", "gaussian",
8692 or "bilateral". The default value is "gaussian".
8694 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
8695 depend on the smooth type. @var{param1} and
8696 @var{param2} accept integer positive values or 0. @var{param3} and
8697 @var{param4} accept floating point values.
8699 The default value for @var{param1} is 3. The default value for the
8700 other parameters is 0.
8702 These parameters correspond to the parameters assigned to the
8703 libopencv function @code{cvSmooth}.
8708 Overlay one video on top of another.
8710 It takes two inputs and has one output. The first input is the "main"
8711 video on which the second input is overlaid.
8713 It accepts the following parameters:
8715 A description of the accepted options follows.
8720 Set the expression for the x and y coordinates of the overlaid video
8721 on the main video. Default value is "0" for both expressions. In case
8722 the expression is invalid, it is set to a huge value (meaning that the
8723 overlay will not be displayed within the output visible area).
8726 The action to take when EOF is encountered on the secondary input; it accepts
8727 one of the following values:
8731 Repeat the last frame (the default).
8735 Pass the main input through.
8739 Set when the expressions for @option{x}, and @option{y} are evaluated.
8741 It accepts the following values:
8744 only evaluate expressions once during the filter initialization or
8745 when a command is processed
8748 evaluate expressions for each incoming frame
8751 Default value is @samp{frame}.
8754 If set to 1, force the output to terminate when the shortest input
8755 terminates. Default value is 0.
8758 Set the format for the output video.
8760 It accepts the following values:
8775 Default value is @samp{yuv420}.
8777 @item rgb @emph{(deprecated)}
8778 If set to 1, force the filter to accept inputs in the RGB
8779 color space. Default value is 0. This option is deprecated, use
8780 @option{format} instead.
8783 If set to 1, force the filter to draw the last overlay frame over the
8784 main input until the end of the stream. A value of 0 disables this
8785 behavior. Default value is 1.
8788 The @option{x}, and @option{y} expressions can contain the following
8794 The main input width and height.
8798 The overlay input width and height.
8802 The computed values for @var{x} and @var{y}. They are evaluated for
8807 horizontal and vertical chroma subsample values of the output
8808 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
8812 the number of input frame, starting from 0
8815 the position in the file of the input frame, NAN if unknown
8818 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
8822 Note that the @var{n}, @var{pos}, @var{t} variables are available only
8823 when evaluation is done @emph{per frame}, and will evaluate to NAN
8824 when @option{eval} is set to @samp{init}.
8826 Be aware that frames are taken from each input video in timestamp
8827 order, hence, if their initial timestamps differ, it is a good idea
8828 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
8829 have them begin in the same zero timestamp, as the example for
8830 the @var{movie} filter does.
8832 You can chain together more overlays but you should test the
8833 efficiency of such approach.
8835 @subsection Commands
8837 This filter supports the following commands:
8841 Modify the x and y of the overlay input.
8842 The command accepts the same syntax of the corresponding option.
8844 If the specified expression is not valid, it is kept at its current
8848 @subsection Examples
8852 Draw the overlay at 10 pixels from the bottom right corner of the main
8855 overlay=main_w-overlay_w-10:main_h-overlay_h-10
8858 Using named options the example above becomes:
8860 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
8864 Insert a transparent PNG logo in the bottom left corner of the input,
8865 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
8867 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
8871 Insert 2 different transparent PNG logos (second logo on bottom
8872 right corner) using the @command{ffmpeg} tool:
8874 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
8878 Add a transparent color layer on top of the main video; @code{WxH}
8879 must specify the size of the main input to the overlay filter:
8881 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
8885 Play an original video and a filtered version (here with the deshake
8886 filter) side by side using the @command{ffplay} tool:
8888 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
8891 The above command is the same as:
8893 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
8897 Make a sliding overlay appearing from the left to the right top part of the
8898 screen starting since time 2:
8900 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
8904 Compose output by putting two input videos side to side:
8906 ffmpeg -i left.avi -i right.avi -filter_complex "
8907 nullsrc=size=200x100 [background];
8908 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
8909 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
8910 [background][left] overlay=shortest=1 [background+left];
8911 [background+left][right] overlay=shortest=1:x=100 [left+right]
8916 Mask 10-20 seconds of a video by applying the delogo filter to a section
8918 ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
8919 -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]'
8924 Chain several overlays in cascade:
8926 nullsrc=s=200x200 [bg];
8927 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
8928 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
8929 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
8930 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
8931 [in3] null, [mid2] overlay=100:100 [out0]
8938 Apply Overcomplete Wavelet denoiser.
8940 The filter accepts the following options:
8946 Larger depth values will denoise lower frequency components more, but
8947 slow down filtering.
8949 Must be an int in the range 8-16, default is @code{8}.
8951 @item luma_strength, ls
8954 Must be a double value in the range 0-1000, default is @code{1.0}.
8956 @item chroma_strength, cs
8957 Set chroma strength.
8959 Must be a double value in the range 0-1000, default is @code{1.0}.
8965 Add paddings to the input image, and place the original input at the
8966 provided @var{x}, @var{y} coordinates.
8968 It accepts the following parameters:
8973 Specify an expression for the size of the output image with the
8974 paddings added. If the value for @var{width} or @var{height} is 0, the
8975 corresponding input size is used for the output.
8977 The @var{width} expression can reference the value set by the
8978 @var{height} expression, and vice versa.
8980 The default value of @var{width} and @var{height} is 0.
8984 Specify the offsets to place the input image at within the padded area,
8985 with respect to the top/left border of the output image.
8987 The @var{x} expression can reference the value set by the @var{y}
8988 expression, and vice versa.
8990 The default value of @var{x} and @var{y} is 0.
8993 Specify the color of the padded area. For the syntax of this option,
8994 check the "Color" section in the ffmpeg-utils manual.
8996 The default value of @var{color} is "black".
8999 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
9000 options are expressions containing the following constants:
9005 The input video width and height.
9009 These are the same as @var{in_w} and @var{in_h}.
9013 The output width and height (the size of the padded area), as
9014 specified by the @var{width} and @var{height} expressions.
9018 These are the same as @var{out_w} and @var{out_h}.
9022 The x and y offsets as specified by the @var{x} and @var{y}
9023 expressions, or NAN if not yet specified.
9026 same as @var{iw} / @var{ih}
9029 input sample aspect ratio
9032 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
9036 The horizontal and vertical chroma subsample values. For example for the
9037 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9040 @subsection Examples
9044 Add paddings with the color "violet" to the input video. The output video
9045 size is 640x480, and the top-left corner of the input video is placed at
9048 pad=640:480:0:40:violet
9051 The example above is equivalent to the following command:
9053 pad=width=640:height=480:x=0:y=40:color=violet
9057 Pad the input to get an output with dimensions increased by 3/2,
9058 and put the input video at the center of the padded area:
9060 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
9064 Pad the input to get a squared output with size equal to the maximum
9065 value between the input width and height, and put the input video at
9066 the center of the padded area:
9068 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
9072 Pad the input to get a final w/h ratio of 16:9:
9074 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
9078 In case of anamorphic video, in order to set the output display aspect
9079 correctly, it is necessary to use @var{sar} in the expression,
9080 according to the relation:
9082 (ih * X / ih) * sar = output_dar
9083 X = output_dar / sar
9086 Thus the previous example needs to be modified to:
9088 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
9092 Double the output size and put the input video in the bottom-right
9093 corner of the output padded area:
9095 pad="2*iw:2*ih:ow-iw:oh-ih"
9102 Generate one palette for a whole video stream.
9104 It accepts the following options:
9108 Set the maximum number of colors to quantize in the palette.
9109 Note: the palette will still contain 256 colors; the unused palette entries
9112 @item reserve_transparent
9113 Create a palette of 255 colors maximum and reserve the last one for
9114 transparency. Reserving the transparency color is useful for GIF optimization.
9115 If not set, the maximum of colors in the palette will be 256. You probably want
9116 to disable this option for a standalone image.
9120 Set statistics mode.
9122 It accepts the following values:
9125 Compute full frame histograms.
9127 Compute histograms only for the part that differs from previous frame. This
9128 might be relevant to give more importance to the moving part of your input if
9129 the background is static.
9132 Default value is @var{full}.
9135 The filter also exports the frame metadata @code{lavfi.color_quant_ratio}
9136 (@code{nb_color_in / nb_color_out}) which you can use to evaluate the degree of
9137 color quantization of the palette. This information is also visible at
9138 @var{info} logging level.
9140 @subsection Examples
9144 Generate a representative palette of a given video using @command{ffmpeg}:
9146 ffmpeg -i input.mkv -vf palettegen palette.png
9152 Use a palette to downsample an input video stream.
9154 The filter takes two inputs: one video stream and a palette. The palette must
9155 be a 256 pixels image.
9157 It accepts the following options:
9161 Select dithering mode. Available algorithms are:
9164 Ordered 8x8 bayer dithering (deterministic)
9166 Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
9167 Note: this dithering is sometimes considered "wrong" and is included as a
9169 @item floyd_steinberg
9170 Floyd and Steingberg dithering (error diffusion)
9172 Frankie Sierra dithering v2 (error diffusion)
9174 Frankie Sierra dithering v2 "Lite" (error diffusion)
9177 Default is @var{sierra2_4a}.
9180 When @var{bayer} dithering is selected, this option defines the scale of the
9181 pattern (how much the crosshatch pattern is visible). A low value means more
9182 visible pattern for less banding, and higher value means less visible pattern
9183 at the cost of more banding.
9185 The option must be an integer value in the range [0,5]. Default is @var{2}.
9188 If set, define the zone to process
9192 Only the changing rectangle will be reprocessed. This is similar to GIF
9193 cropping/offsetting compression mechanism. This option can be useful for speed
9194 if only a part of the image is changing, and has use cases such as limiting the
9195 scope of the error diffusal @option{dither} to the rectangle that bounds the
9196 moving scene (it leads to more deterministic output if the scene doesn't change
9197 much, and as a result less moving noise and better GIF compression).
9200 Default is @var{none}.
9203 @subsection Examples
9207 Use a palette (generated for example with @ref{palettegen}) to encode a GIF
9208 using @command{ffmpeg}:
9210 ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
9214 @section perspective
9216 Correct perspective of video not recorded perpendicular to the screen.
9218 A description of the accepted parameters follows.
9229 Set coordinates expression for top left, top right, bottom left and bottom right corners.
9230 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
9231 If the @code{sense} option is set to @code{source}, then the specified points will be sent
9232 to the corners of the destination. If the @code{sense} option is set to @code{destination},
9233 then the corners of the source will be sent to the specified coordinates.
9235 The expressions can use the following variables:
9240 the width and height of video frame.
9244 Set interpolation for perspective correction.
9246 It accepts the following values:
9252 Default value is @samp{linear}.
9255 Set interpretation of coordinate options.
9257 It accepts the following values:
9261 Send point in the source specified by the given coordinates to
9262 the corners of the destination.
9264 @item 1, destination
9266 Send the corners of the source to the point in the destination specified
9267 by the given coordinates.
9269 Default value is @samp{source}.
9275 Delay interlaced video by one field time so that the field order changes.
9277 The intended use is to fix PAL movies that have been captured with the
9278 opposite field order to the film-to-video transfer.
9280 A description of the accepted parameters follows.
9286 It accepts the following values:
9289 Capture field order top-first, transfer bottom-first.
9290 Filter will delay the bottom field.
9293 Capture field order bottom-first, transfer top-first.
9294 Filter will delay the top field.
9297 Capture and transfer with the same field order. This mode only exists
9298 for the documentation of the other options to refer to, but if you
9299 actually select it, the filter will faithfully do nothing.
9302 Capture field order determined automatically by field flags, transfer
9304 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
9305 basis using field flags. If no field information is available,
9306 then this works just like @samp{u}.
9309 Capture unknown or varying, transfer opposite.
9310 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
9311 analyzing the images and selecting the alternative that produces best
9312 match between the fields.
9315 Capture top-first, transfer unknown or varying.
9316 Filter selects among @samp{t} and @samp{p} using image analysis.
9319 Capture bottom-first, transfer unknown or varying.
9320 Filter selects among @samp{b} and @samp{p} using image analysis.
9323 Capture determined by field flags, transfer unknown or varying.
9324 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
9325 image analysis. If no field information is available, then this works just
9326 like @samp{U}. This is the default mode.
9329 Both capture and transfer unknown or varying.
9330 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
9334 @section pixdesctest
9336 Pixel format descriptor test filter, mainly useful for internal
9337 testing. The output video should be equal to the input video.
9341 format=monow, pixdesctest
9344 can be used to test the monowhite pixel format descriptor definition.
9348 Enable the specified chain of postprocessing subfilters using libpostproc. This
9349 library should be automatically selected with a GPL build (@code{--enable-gpl}).
9350 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
9351 Each subfilter and some options have a short and a long name that can be used
9352 interchangeably, i.e. dr/dering are the same.
9354 The filters accept the following options:
9358 Set postprocessing subfilters string.
9361 All subfilters share common options to determine their scope:
9365 Honor the quality commands for this subfilter.
9368 Do chrominance filtering, too (default).
9371 Do luminance filtering only (no chrominance).
9374 Do chrominance filtering only (no luminance).
9377 These options can be appended after the subfilter name, separated by a '|'.
9379 Available subfilters are:
9382 @item hb/hdeblock[|difference[|flatness]]
9383 Horizontal deblocking filter
9386 Difference factor where higher values mean more deblocking (default: @code{32}).
9388 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9391 @item vb/vdeblock[|difference[|flatness]]
9392 Vertical deblocking filter
9395 Difference factor where higher values mean more deblocking (default: @code{32}).
9397 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9400 @item ha/hadeblock[|difference[|flatness]]
9401 Accurate horizontal deblocking filter
9404 Difference factor where higher values mean more deblocking (default: @code{32}).
9406 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9409 @item va/vadeblock[|difference[|flatness]]
9410 Accurate vertical deblocking filter
9413 Difference factor where higher values mean more deblocking (default: @code{32}).
9415 Flatness threshold where lower values mean more deblocking (default: @code{39}).
9419 The horizontal and vertical deblocking filters share the difference and
9420 flatness values so you cannot set different horizontal and vertical
9425 Experimental horizontal deblocking filter
9428 Experimental vertical deblocking filter
9433 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
9436 larger -> stronger filtering
9438 larger -> stronger filtering
9440 larger -> stronger filtering
9443 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
9446 Stretch luminance to @code{0-255}.
9449 @item lb/linblenddeint
9450 Linear blend deinterlacing filter that deinterlaces the given block by
9451 filtering all lines with a @code{(1 2 1)} filter.
9453 @item li/linipoldeint
9454 Linear interpolating deinterlacing filter that deinterlaces the given block by
9455 linearly interpolating every second line.
9457 @item ci/cubicipoldeint
9458 Cubic interpolating deinterlacing filter deinterlaces the given block by
9459 cubically interpolating every second line.
9461 @item md/mediandeint
9462 Median deinterlacing filter that deinterlaces the given block by applying a
9463 median filter to every second line.
9465 @item fd/ffmpegdeint
9466 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
9467 second line with a @code{(-1 4 2 4 -1)} filter.
9470 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
9471 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
9473 @item fq/forceQuant[|quantizer]
9474 Overrides the quantizer table from the input with the constant quantizer you
9482 Default pp filter combination (@code{hb|a,vb|a,dr|a})
9485 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
9488 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
9491 @subsection Examples
9495 Apply horizontal and vertical deblocking, deringing and automatic
9496 brightness/contrast:
9502 Apply default filters without brightness/contrast correction:
9508 Apply default filters and temporal denoiser:
9510 pp=default/tmpnoise|1|2|3
9514 Apply deblocking on luminance only, and switch vertical deblocking on or off
9515 automatically depending on available CPU time:
9522 Apply Postprocessing filter 7. It is variant of the @ref{spp} filter,
9523 similar to spp = 6 with 7 point DCT, where only the center sample is
9526 The filter accepts the following options:
9530 Force a constant quantization parameter. It accepts an integer in range
9531 0 to 63. If not set, the filter will use the QP from the video stream
9535 Set thresholding mode. Available modes are:
9539 Set hard thresholding.
9541 Set soft thresholding (better de-ringing effect, but likely blurrier).
9543 Set medium thresholding (good results, default).
9549 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
9550 Ratio) between two input videos.
9552 This filter takes in input two input videos, the first input is
9553 considered the "main" source and is passed unchanged to the
9554 output. The second input is used as a "reference" video for computing
9557 Both video inputs must have the same resolution and pixel format for
9558 this filter to work correctly. Also it assumes that both inputs
9559 have the same number of frames, which are compared one by one.
9561 The obtained average PSNR is printed through the logging system.
9563 The filter stores the accumulated MSE (mean squared error) of each
9564 frame, and at the end of the processing it is averaged across all frames
9565 equally, and the following formula is applied to obtain the PSNR:
9568 PSNR = 10*log10(MAX^2/MSE)
9571 Where MAX is the average of the maximum values of each component of the
9574 The description of the accepted parameters follows.
9578 If specified the filter will use the named file to save the PSNR of
9579 each individual frame. When filename equals "-" the data is sent to
9583 The file printed if @var{stats_file} is selected, contains a sequence of
9584 key/value pairs of the form @var{key}:@var{value} for each compared
9587 A description of each shown parameter follows:
9591 sequential number of the input frame, starting from 1
9594 Mean Square Error pixel-by-pixel average difference of the compared
9595 frames, averaged over all the image components.
9597 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
9598 Mean Square Error pixel-by-pixel average difference of the compared
9599 frames for the component specified by the suffix.
9601 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
9602 Peak Signal to Noise ratio of the compared frames for the component
9603 specified by the suffix.
9608 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
9609 [main][ref] psnr="stats_file=stats.log" [out]
9612 On this example the input file being processed is compared with the
9613 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
9614 is stored in @file{stats.log}.
9619 Pulldown reversal (inverse telecine) filter, capable of handling mixed
9620 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
9623 The pullup filter is designed to take advantage of future context in making
9624 its decisions. This filter is stateless in the sense that it does not lock
9625 onto a pattern to follow, but it instead looks forward to the following
9626 fields in order to identify matches and rebuild progressive frames.
9628 To produce content with an even framerate, insert the fps filter after
9629 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
9630 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
9632 The filter accepts the following options:
9639 These options set the amount of "junk" to ignore at the left, right, top, and
9640 bottom of the image, respectively. Left and right are in units of 8 pixels,
9641 while top and bottom are in units of 2 lines.
9642 The default is 8 pixels on each side.
9645 Set the strict breaks. Setting this option to 1 will reduce the chances of
9646 filter generating an occasional mismatched frame, but it may also cause an
9647 excessive number of frames to be dropped during high motion sequences.
9648 Conversely, setting it to -1 will make filter match fields more easily.
9649 This may help processing of video where there is slight blurring between
9650 the fields, but may also cause there to be interlaced frames in the output.
9651 Default value is @code{0}.
9654 Set the metric plane to use. It accepts the following values:
9660 Use chroma blue plane.
9663 Use chroma red plane.
9666 This option may be set to use chroma plane instead of the default luma plane
9667 for doing filter's computations. This may improve accuracy on very clean
9668 source material, but more likely will decrease accuracy, especially if there
9669 is chroma noise (rainbow effect) or any grayscale video.
9670 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
9671 load and make pullup usable in realtime on slow machines.
9674 For best results (without duplicated frames in the output file) it is
9675 necessary to change the output frame rate. For example, to inverse
9676 telecine NTSC input:
9678 ffmpeg -i input -vf pullup -r 24000/1001 ...
9683 Change video quantization parameters (QP).
9685 The filter accepts the following option:
9689 Set expression for quantization parameter.
9692 The expression is evaluated through the eval API and can contain, among others,
9693 the following constants:
9697 1 if index is not 129, 0 otherwise.
9700 Sequentional index starting from -129 to 128.
9703 @subsection Examples
9715 Flush video frames from internal cache of frames into a random order.
9716 No frame is discarded.
9717 Inspired by @ref{frei0r} nervous filter.
9721 Set size in number of frames of internal cache, in range from @code{2} to
9722 @code{512}. Default is @code{30}.
9725 Set seed for random number generator, must be an integer included between
9726 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9727 less than @code{0}, the filter will try to use a good random seed on a
9731 @section removegrain
9733 The removegrain filter is a spatial denoiser for progressive video.
9737 Set mode for the first plane.
9740 Set mode for the second plane.
9743 Set mode for the third plane.
9746 Set mode for the fourth plane.
9749 Range of mode is from 0 to 24. Description of each mode follows:
9753 Leave input plane unchanged. Default.
9756 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
9759 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
9762 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
9765 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
9766 This is equivalent to a median filter.
9769 Line-sensitive clipping giving the minimal change.
9772 Line-sensitive clipping, intermediate.
9775 Line-sensitive clipping, intermediate.
9778 Line-sensitive clipping, intermediate.
9781 Line-sensitive clipping on a line where the neighbours pixels are the closest.
9784 Replaces the target pixel with the closest neighbour.
9787 [1 2 1] horizontal and vertical kernel blur.
9793 Bob mode, interpolates top field from the line where the neighbours
9794 pixels are the closest.
9797 Bob mode, interpolates bottom field from the line where the neighbours
9798 pixels are the closest.
9801 Bob mode, interpolates top field. Same as 13 but with a more complicated
9802 interpolation formula.
9805 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
9806 interpolation formula.
9809 Clips the pixel with the minimum and maximum of respectively the maximum and
9810 minimum of each pair of opposite neighbour pixels.
9813 Line-sensitive clipping using opposite neighbours whose greatest distance from
9814 the current pixel is minimal.
9817 Replaces the pixel with the average of its 8 neighbours.
9820 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
9823 Clips pixels using the averages of opposite neighbour.
9826 Same as mode 21 but simpler and faster.
9829 Small edge and halo removal, but reputed useless.
9837 Suppress a TV station logo, using an image file to determine which
9838 pixels comprise the logo. It works by filling in the pixels that
9839 comprise the logo with neighboring pixels.
9841 The filter accepts the following options:
9845 Set the filter bitmap file, which can be any image format supported by
9846 libavformat. The width and height of the image file must match those of the
9847 video stream being processed.
9850 Pixels in the provided bitmap image with a value of zero are not
9851 considered part of the logo, non-zero pixels are considered part of
9852 the logo. If you use white (255) for the logo and black (0) for the
9853 rest, you will be safe. For making the filter bitmap, it is
9854 recommended to take a screen capture of a black frame with the logo
9855 visible, and then using a threshold filter followed by the erode
9856 filter once or twice.
9858 If needed, little splotches can be fixed manually. Remember that if
9859 logo pixels are not covered, the filter quality will be much
9860 reduced. Marking too many pixels as part of the logo does not hurt as
9861 much, but it will increase the amount of blurring needed to cover over
9862 the image and will destroy more information than necessary, and extra
9863 pixels will slow things down on a large logo.
9865 @section repeatfields
9867 This filter uses the repeat_field flag from the Video ES headers and hard repeats
9868 fields based on its value.
9870 @section reverse, areverse
9874 Warning: This filter requires memory to buffer the entire clip, so trimming
9877 @subsection Examples
9881 Take the first 5 seconds of a clip, and reverse it.
9889 Rotate video by an arbitrary angle expressed in radians.
9891 The filter accepts the following options:
9893 A description of the optional parameters follows.
9896 Set an expression for the angle by which to rotate the input video
9897 clockwise, expressed as a number of radians. A negative value will
9898 result in a counter-clockwise rotation. By default it is set to "0".
9900 This expression is evaluated for each frame.
9903 Set the output width expression, default value is "iw".
9904 This expression is evaluated just once during configuration.
9907 Set the output height expression, default value is "ih".
9908 This expression is evaluated just once during configuration.
9911 Enable bilinear interpolation if set to 1, a value of 0 disables
9912 it. Default value is 1.
9915 Set the color used to fill the output area not covered by the rotated
9916 image. For the general syntax of this option, check the "Color" section in the
9917 ffmpeg-utils manual. If the special value "none" is selected then no
9918 background is printed (useful for example if the background is never shown).
9920 Default value is "black".
9923 The expressions for the angle and the output size can contain the
9924 following constants and functions:
9928 sequential number of the input frame, starting from 0. It is always NAN
9929 before the first frame is filtered.
9932 time in seconds of the input frame, it is set to 0 when the filter is
9933 configured. It is always NAN before the first frame is filtered.
9937 horizontal and vertical chroma subsample values. For example for the
9938 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9942 the input video width and height
9946 the output width and height, that is the size of the padded area as
9947 specified by the @var{width} and @var{height} expressions
9951 the minimal width/height required for completely containing the input
9952 video rotated by @var{a} radians.
9954 These are only available when computing the @option{out_w} and
9955 @option{out_h} expressions.
9958 @subsection Examples
9962 Rotate the input by PI/6 radians clockwise:
9968 Rotate the input by PI/6 radians counter-clockwise:
9974 Rotate the input by 45 degrees clockwise:
9980 Apply a constant rotation with period T, starting from an angle of PI/3:
9982 rotate=PI/3+2*PI*t/T
9986 Make the input video rotation oscillating with a period of T
9987 seconds and an amplitude of A radians:
9989 rotate=A*sin(2*PI/T*t)
9993 Rotate the video, output size is chosen so that the whole rotating
9994 input video is always completely contained in the output:
9996 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
10000 Rotate the video, reduce the output size so that no background is ever
10003 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
10007 @subsection Commands
10009 The filter supports the following commands:
10013 Set the angle expression.
10014 The command accepts the same syntax of the corresponding option.
10016 If the specified expression is not valid, it is kept at its current
10022 Apply Shape Adaptive Blur.
10024 The filter accepts the following options:
10027 @item luma_radius, lr
10028 Set luma blur filter strength, must be a value in range 0.1-4.0, default
10029 value is 1.0. A greater value will result in a more blurred image, and
10030 in slower processing.
10032 @item luma_pre_filter_radius, lpfr
10033 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
10036 @item luma_strength, ls
10037 Set luma maximum difference between pixels to still be considered, must
10038 be a value in the 0.1-100.0 range, default value is 1.0.
10040 @item chroma_radius, cr
10041 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
10042 greater value will result in a more blurred image, and in slower
10045 @item chroma_pre_filter_radius, cpfr
10046 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
10048 @item chroma_strength, cs
10049 Set chroma maximum difference between pixels to still be considered,
10050 must be a value in the 0.1-100.0 range.
10053 Each chroma option value, if not explicitly specified, is set to the
10054 corresponding luma option value.
10059 Scale (resize) the input video, using the libswscale library.
10061 The scale filter forces the output display aspect ratio to be the same
10062 of the input, by changing the output sample aspect ratio.
10064 If the input image format is different from the format requested by
10065 the next filter, the scale filter will convert the input to the
10068 @subsection Options
10069 The filter accepts the following options, or any of the options
10070 supported by the libswscale scaler.
10072 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
10073 the complete list of scaler options.
10078 Set the output video dimension expression. Default value is the input
10081 If the value is 0, the input width is used for the output.
10083 If one of the values is -1, the scale filter will use a value that
10084 maintains the aspect ratio of the input image, calculated from the
10085 other specified dimension. If both of them are -1, the input size is
10088 If one of the values is -n with n > 1, the scale filter will also use a value
10089 that maintains the aspect ratio of the input image, calculated from the other
10090 specified dimension. After that it will, however, make sure that the calculated
10091 dimension is divisible by n and adjust the value if necessary.
10093 See below for the list of accepted constants for use in the dimension
10097 Specify when to evaluate @var{width} and @var{height} expression. It accepts the following values:
10101 Only evaluate expressions once during the filter initialization or when a command is processed.
10104 Evaluate expressions for each incoming frame.
10108 Default value is @samp{init}.
10112 Set the interlacing mode. It accepts the following values:
10116 Force interlaced aware scaling.
10119 Do not apply interlaced scaling.
10122 Select interlaced aware scaling depending on whether the source frames
10123 are flagged as interlaced or not.
10126 Default value is @samp{0}.
10129 Set libswscale scaling flags. See
10130 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
10131 complete list of values. If not explicitly specified the filter applies
10135 @item param0, param1
10136 Set libswscale input parameters for scaling algorithms that need them. See
10137 @ref{sws_params,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
10138 complete documentation. If not explicitly specified the filter applies
10144 Set the video size. For the syntax of this option, check the
10145 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10147 @item in_color_matrix
10148 @item out_color_matrix
10149 Set in/output YCbCr color space type.
10151 This allows the autodetected value to be overridden as well as allows forcing
10152 a specific value used for the output and encoder.
10154 If not specified, the color space type depends on the pixel format.
10160 Choose automatically.
10163 Format conforming to International Telecommunication Union (ITU)
10164 Recommendation BT.709.
10167 Set color space conforming to the United States Federal Communications
10168 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
10171 Set color space conforming to:
10175 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
10178 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
10181 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
10186 Set color space conforming to SMPTE ST 240:1999.
10191 Set in/output YCbCr sample range.
10193 This allows the autodetected value to be overridden as well as allows forcing
10194 a specific value used for the output and encoder. If not specified, the
10195 range depends on the pixel format. Possible values:
10199 Choose automatically.
10202 Set full range (0-255 in case of 8-bit luma).
10205 Set "MPEG" range (16-235 in case of 8-bit luma).
10208 @item force_original_aspect_ratio
10209 Enable decreasing or increasing output video width or height if necessary to
10210 keep the original aspect ratio. Possible values:
10214 Scale the video as specified and disable this feature.
10217 The output video dimensions will automatically be decreased if needed.
10220 The output video dimensions will automatically be increased if needed.
10224 One useful instance of this option is that when you know a specific device's
10225 maximum allowed resolution, you can use this to limit the output video to
10226 that, while retaining the aspect ratio. For example, device A allows
10227 1280x720 playback, and your video is 1920x800. Using this option (set it to
10228 decrease) and specifying 1280x720 to the command line makes the output
10231 Please note that this is a different thing than specifying -1 for @option{w}
10232 or @option{h}, you still need to specify the output resolution for this option
10237 The values of the @option{w} and @option{h} options are expressions
10238 containing the following constants:
10243 The input width and height
10247 These are the same as @var{in_w} and @var{in_h}.
10251 The output (scaled) width and height
10255 These are the same as @var{out_w} and @var{out_h}
10258 The same as @var{iw} / @var{ih}
10261 input sample aspect ratio
10264 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
10268 horizontal and vertical input chroma subsample values. For example for the
10269 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10273 horizontal and vertical output chroma subsample values. For example for the
10274 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10277 @subsection Examples
10281 Scale the input video to a size of 200x100
10286 This is equivalent to:
10297 Specify a size abbreviation for the output size:
10302 which can also be written as:
10308 Scale the input to 2x:
10310 scale=w=2*iw:h=2*ih
10314 The above is the same as:
10316 scale=2*in_w:2*in_h
10320 Scale the input to 2x with forced interlaced scaling:
10322 scale=2*iw:2*ih:interl=1
10326 Scale the input to half size:
10328 scale=w=iw/2:h=ih/2
10332 Increase the width, and set the height to the same size:
10338 Seek Greek harmony:
10345 Increase the height, and set the width to 3/2 of the height:
10347 scale=w=3/2*oh:h=3/5*ih
10351 Increase the size, making the size a multiple of the chroma
10354 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
10358 Increase the width to a maximum of 500 pixels,
10359 keeping the same aspect ratio as the input:
10361 scale=w='min(500\, iw*3/2):h=-1'
10365 @subsection Commands
10367 This filter supports the following commands:
10371 Set the output video dimension expression.
10372 The command accepts the same syntax of the corresponding option.
10374 If the specified expression is not valid, it is kept at its current
10380 Scale (resize) the input video, based on a reference video.
10382 See the scale filter for available options, scale2ref supports the same but
10383 uses the reference video instead of the main input as basis.
10385 @subsection Examples
10389 Scale a subtitle stream to match the main video in size before overlaying
10391 'scale2ref[b][a];[a][b]overlay'
10395 @section selectivecolor
10397 Adjust cyan, magenta, yellow and black (CMYK) to certain ranges of colors (such
10398 as "reds", "yellows", "greens", "cyans", ...). The adjustment range is defined
10399 by the "purity" of the color (that is, how saturated it already is).
10401 This filter is similar to the Adobe Photoshop Selective Color tool.
10403 The filter accepts the following options:
10406 @item correction_method
10407 Select color correction method.
10409 Available values are:
10412 Specified adjustments are applied "as-is" (added/subtracted to original pixel
10415 Specified adjustments are relative to the original component value.
10417 Default is @code{absolute}.
10419 Adjustments for red pixels (pixels where the red component is the maximum)
10421 Adjustments for yellow pixels (pixels where the blue component is the minimum)
10423 Adjustments for green pixels (pixels where the green component is the maximum)
10425 Adjustments for cyan pixels (pixels where the red component is the minimum)
10427 Adjustments for blue pixels (pixels where the blue component is the maximum)
10429 Adjustments for magenta pixels (pixels where the green component is the minimum)
10431 Adjustments for white pixels (pixels where all components are greater than 128)
10433 Adjustments for all pixels except pure black and pure white
10435 Adjustments for black pixels (pixels where all components are lesser than 128)
10437 Specify a Photoshop selective color file (@code{.asv}) to import the settings from.
10440 All the adjustment settings (@option{reds}, @option{yellows}, ...) accept up to
10441 4 space separated floating point adjustment values in the [-1,1] range,
10442 respectively to adjust the amount of cyan, magenta, yellow and black for the
10443 pixels of its range.
10445 @subsection Examples
10449 Increase cyan by 50% and reduce yellow by 33% in every green areas, and
10450 increase magenta by 27% in blue areas:
10452 selectivecolor=greens=.5 0 -.33 0:blues=0 .27
10456 Use a Photoshop selective color preset:
10458 selectivecolor=psfile=MySelectiveColorPresets/Misty.asv
10462 @section separatefields
10464 The @code{separatefields} takes a frame-based video input and splits
10465 each frame into its components fields, producing a new half height clip
10466 with twice the frame rate and twice the frame count.
10468 This filter use field-dominance information in frame to decide which
10469 of each pair of fields to place first in the output.
10470 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
10472 @section setdar, setsar
10474 The @code{setdar} filter sets the Display Aspect Ratio for the filter
10477 This is done by changing the specified Sample (aka Pixel) Aspect
10478 Ratio, according to the following equation:
10480 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
10483 Keep in mind that the @code{setdar} filter does not modify the pixel
10484 dimensions of the video frame. Also, the display aspect ratio set by
10485 this filter may be changed by later filters in the filterchain,
10486 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
10489 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
10490 the filter output video.
10492 Note that as a consequence of the application of this filter, the
10493 output display aspect ratio will change according to the equation
10496 Keep in mind that the sample aspect ratio set by the @code{setsar}
10497 filter may be changed by later filters in the filterchain, e.g. if
10498 another "setsar" or a "setdar" filter is applied.
10500 It accepts the following parameters:
10503 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
10504 Set the aspect ratio used by the filter.
10506 The parameter can be a floating point number string, an expression, or
10507 a string of the form @var{num}:@var{den}, where @var{num} and
10508 @var{den} are the numerator and denominator of the aspect ratio. If
10509 the parameter is not specified, it is assumed the value "0".
10510 In case the form "@var{num}:@var{den}" is used, the @code{:} character
10514 Set the maximum integer value to use for expressing numerator and
10515 denominator when reducing the expressed aspect ratio to a rational.
10516 Default value is @code{100}.
10520 The parameter @var{sar} is an expression containing
10521 the following constants:
10525 These are approximated values for the mathematical constants e
10526 (Euler's number), pi (Greek pi), and phi (the golden ratio).
10529 The input width and height.
10532 These are the same as @var{w} / @var{h}.
10535 The input sample aspect ratio.
10538 The input display aspect ratio. It is the same as
10539 (@var{w} / @var{h}) * @var{sar}.
10542 Horizontal and vertical chroma subsample values. For example, for the
10543 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
10546 @subsection Examples
10551 To change the display aspect ratio to 16:9, specify one of the following:
10559 To change the sample aspect ratio to 10:11, specify:
10565 To set a display aspect ratio of 16:9, and specify a maximum integer value of
10566 1000 in the aspect ratio reduction, use the command:
10568 setdar=ratio=16/9:max=1000
10576 Force field for the output video frame.
10578 The @code{setfield} filter marks the interlace type field for the
10579 output frames. It does not change the input frame, but only sets the
10580 corresponding property, which affects how the frame is treated by
10581 following filters (e.g. @code{fieldorder} or @code{yadif}).
10583 The filter accepts the following options:
10588 Available values are:
10592 Keep the same field property.
10595 Mark the frame as bottom-field-first.
10598 Mark the frame as top-field-first.
10601 Mark the frame as progressive.
10607 Show a line containing various information for each input video frame.
10608 The input video is not modified.
10610 The shown line contains a sequence of key/value pairs of the form
10611 @var{key}:@var{value}.
10613 The following values are shown in the output:
10617 The (sequential) number of the input frame, starting from 0.
10620 The Presentation TimeStamp of the input frame, expressed as a number of
10621 time base units. The time base unit depends on the filter input pad.
10624 The Presentation TimeStamp of the input frame, expressed as a number of
10628 The position of the frame in the input stream, or -1 if this information is
10629 unavailable and/or meaningless (for example in case of synthetic video).
10632 The pixel format name.
10635 The sample aspect ratio of the input frame, expressed in the form
10636 @var{num}/@var{den}.
10639 The size of the input frame. For the syntax of this option, check the
10640 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10643 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
10644 for bottom field first).
10647 This is 1 if the frame is a key frame, 0 otherwise.
10650 The picture type of the input frame ("I" for an I-frame, "P" for a
10651 P-frame, "B" for a B-frame, or "?" for an unknown type).
10652 Also refer to the documentation of the @code{AVPictureType} enum and of
10653 the @code{av_get_picture_type_char} function defined in
10654 @file{libavutil/avutil.h}.
10657 The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
10659 @item plane_checksum
10660 The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
10661 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]".
10664 @section showpalette
10666 Displays the 256 colors palette of each frame. This filter is only relevant for
10667 @var{pal8} pixel format frames.
10669 It accepts the following option:
10673 Set the size of the box used to represent one palette color entry. Default is
10674 @code{30} (for a @code{30x30} pixel box).
10677 @section shuffleframes
10679 Reorder and/or duplicate video frames.
10681 It accepts the following parameters:
10685 Set the destination indexes of input frames.
10686 This is space or '|' separated list of indexes that maps input frames to output
10687 frames. Number of indexes also sets maximal value that each index may have.
10690 The first frame has the index 0. The default is to keep the input unchanged.
10692 Swap second and third frame of every three frames of the input:
10694 ffmpeg -i INPUT -vf "shuffleframes=0 2 1" OUTPUT
10697 @section shuffleplanes
10699 Reorder and/or duplicate video planes.
10701 It accepts the following parameters:
10706 The index of the input plane to be used as the first output plane.
10709 The index of the input plane to be used as the second output plane.
10712 The index of the input plane to be used as the third output plane.
10715 The index of the input plane to be used as the fourth output plane.
10719 The first plane has the index 0. The default is to keep the input unchanged.
10721 Swap the second and third planes of the input:
10723 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
10726 @anchor{signalstats}
10727 @section signalstats
10728 Evaluate various visual metrics that assist in determining issues associated
10729 with the digitization of analog video media.
10731 By default the filter will log these metadata values:
10735 Display the minimal Y value contained within the input frame. Expressed in
10739 Display the Y value at the 10% percentile within the input frame. Expressed in
10743 Display the average Y value within the input frame. Expressed in range of
10747 Display the Y value at the 90% percentile within the input frame. Expressed in
10751 Display the maximum Y value contained within the input frame. Expressed in
10755 Display the minimal U value contained within the input frame. Expressed in
10759 Display the U value at the 10% percentile within the input frame. Expressed in
10763 Display the average U value within the input frame. Expressed in range of
10767 Display the U value at the 90% percentile within the input frame. Expressed in
10771 Display the maximum U value contained within the input frame. Expressed in
10775 Display the minimal V value contained within the input frame. Expressed in
10779 Display the V value at the 10% percentile within the input frame. Expressed in
10783 Display the average V value within the input frame. Expressed in range of
10787 Display the V value at the 90% percentile within the input frame. Expressed in
10791 Display the maximum V value contained within the input frame. Expressed in
10795 Display the minimal saturation value contained within the input frame.
10796 Expressed in range of [0-~181.02].
10799 Display the saturation value at the 10% percentile within the input frame.
10800 Expressed in range of [0-~181.02].
10803 Display the average saturation value within the input frame. Expressed in range
10807 Display the saturation value at the 90% percentile within the input frame.
10808 Expressed in range of [0-~181.02].
10811 Display the maximum saturation value contained within the input frame.
10812 Expressed in range of [0-~181.02].
10815 Display the median value for hue within the input frame. Expressed in range of
10819 Display the average value for hue within the input frame. Expressed in range of
10823 Display the average of sample value difference between all values of the Y
10824 plane in the current frame and corresponding values of the previous input frame.
10825 Expressed in range of [0-255].
10828 Display the average of sample value difference between all values of the U
10829 plane in the current frame and corresponding values of the previous input frame.
10830 Expressed in range of [0-255].
10833 Display the average of sample value difference between all values of the V
10834 plane in the current frame and corresponding values of the previous input frame.
10835 Expressed in range of [0-255].
10838 The filter accepts the following options:
10844 @option{stat} specify an additional form of image analysis.
10845 @option{out} output video with the specified type of pixel highlighted.
10847 Both options accept the following values:
10851 Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel
10852 unlike the neighboring pixels of the same field. Examples of temporal outliers
10853 include the results of video dropouts, head clogs, or tape tracking issues.
10856 Identify @var{vertical line repetition}. Vertical line repetition includes
10857 similar rows of pixels within a frame. In born-digital video vertical line
10858 repetition is common, but this pattern is uncommon in video digitized from an
10859 analog source. When it occurs in video that results from the digitization of an
10860 analog source it can indicate concealment from a dropout compensator.
10863 Identify pixels that fall outside of legal broadcast range.
10867 Set the highlight color for the @option{out} option. The default color is
10871 @subsection Examples
10875 Output data of various video metrics:
10877 ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
10881 Output specific data about the minimum and maximum values of the Y plane per frame:
10883 ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
10887 Playback video while highlighting pixels that are outside of broadcast range in red.
10889 ffplay example.mov -vf signalstats="out=brng:color=red"
10893 Playback video with signalstats metadata drawn over the frame.
10895 ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
10898 The contents of signalstat_drawtext.txt used in the command are:
10901 Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@})
10902 U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@})
10903 V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@})
10904 saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@}
10912 Blur the input video without impacting the outlines.
10914 It accepts the following options:
10917 @item luma_radius, lr
10918 Set the luma radius. The option value must be a float number in
10919 the range [0.1,5.0] that specifies the variance of the gaussian filter
10920 used to blur the image (slower if larger). Default value is 1.0.
10922 @item luma_strength, ls
10923 Set the luma strength. The option value must be a float number
10924 in the range [-1.0,1.0] that configures the blurring. A value included
10925 in [0.0,1.0] will blur the image whereas a value included in
10926 [-1.0,0.0] will sharpen the image. Default value is 1.0.
10928 @item luma_threshold, lt
10929 Set the luma threshold used as a coefficient to determine
10930 whether a pixel should be blurred or not. The option value must be an
10931 integer in the range [-30,30]. A value of 0 will filter all the image,
10932 a value included in [0,30] will filter flat areas and a value included
10933 in [-30,0] will filter edges. Default value is 0.
10935 @item chroma_radius, cr
10936 Set the chroma radius. The option value must be a float number in
10937 the range [0.1,5.0] that specifies the variance of the gaussian filter
10938 used to blur the image (slower if larger). Default value is 1.0.
10940 @item chroma_strength, cs
10941 Set the chroma strength. The option value must be a float number
10942 in the range [-1.0,1.0] that configures the blurring. A value included
10943 in [0.0,1.0] will blur the image whereas a value included in
10944 [-1.0,0.0] will sharpen the image. Default value is 1.0.
10946 @item chroma_threshold, ct
10947 Set the chroma threshold used as a coefficient to determine
10948 whether a pixel should be blurred or not. The option value must be an
10949 integer in the range [-30,30]. A value of 0 will filter all the image,
10950 a value included in [0,30] will filter flat areas and a value included
10951 in [-30,0] will filter edges. Default value is 0.
10954 If a chroma option is not explicitly set, the corresponding luma value
10959 Obtain the SSIM (Structural SImilarity Metric) between two input videos.
10961 This filter takes in input two input videos, the first input is
10962 considered the "main" source and is passed unchanged to the
10963 output. The second input is used as a "reference" video for computing
10966 Both video inputs must have the same resolution and pixel format for
10967 this filter to work correctly. Also it assumes that both inputs
10968 have the same number of frames, which are compared one by one.
10970 The filter stores the calculated SSIM of each frame.
10972 The description of the accepted parameters follows.
10975 @item stats_file, f
10976 If specified the filter will use the named file to save the SSIM of
10977 each individual frame. When filename equals "-" the data is sent to
10981 The file printed if @var{stats_file} is selected, contains a sequence of
10982 key/value pairs of the form @var{key}:@var{value} for each compared
10985 A description of each shown parameter follows:
10989 sequential number of the input frame, starting from 1
10991 @item Y, U, V, R, G, B
10992 SSIM of the compared frames for the component specified by the suffix.
10995 SSIM of the compared frames for the whole frame.
10998 Same as above but in dB representation.
11003 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
11004 [main][ref] ssim="stats_file=stats.log" [out]
11007 On this example the input file being processed is compared with the
11008 reference file @file{ref_movie.mpg}. The SSIM of each individual frame
11009 is stored in @file{stats.log}.
11011 Another example with both psnr and ssim at same time:
11013 ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
11018 Convert between different stereoscopic image formats.
11020 The filters accept the following options:
11024 Set stereoscopic image format of input.
11026 Available values for input image formats are:
11029 side by side parallel (left eye left, right eye right)
11032 side by side crosseye (right eye left, left eye right)
11035 side by side parallel with half width resolution
11036 (left eye left, right eye right)
11039 side by side crosseye with half width resolution
11040 (right eye left, left eye right)
11043 above-below (left eye above, right eye below)
11046 above-below (right eye above, left eye below)
11049 above-below with half height resolution
11050 (left eye above, right eye below)
11053 above-below with half height resolution
11054 (right eye above, left eye below)
11057 alternating frames (left eye first, right eye second)
11060 alternating frames (right eye first, left eye second)
11063 interleaved rows (left eye has top row, right eye starts on next row)
11066 interleaved rows (right eye has top row, left eye starts on next row)
11069 interleaved columns, left eye first
11072 interleaved columns, right eye first
11074 Default value is @samp{sbsl}.
11078 Set stereoscopic image format of output.
11082 side by side parallel (left eye left, right eye right)
11085 side by side crosseye (right eye left, left eye right)
11088 side by side parallel with half width resolution
11089 (left eye left, right eye right)
11092 side by side crosseye with half width resolution
11093 (right eye left, left eye right)
11096 above-below (left eye above, right eye below)
11099 above-below (right eye above, left eye below)
11102 above-below with half height resolution
11103 (left eye above, right eye below)
11106 above-below with half height resolution
11107 (right eye above, left eye below)
11110 alternating frames (left eye first, right eye second)
11113 alternating frames (right eye first, left eye second)
11116 interleaved rows (left eye has top row, right eye starts on next row)
11119 interleaved rows (right eye has top row, left eye starts on next row)
11122 anaglyph red/blue gray
11123 (red filter on left eye, blue filter on right eye)
11126 anaglyph red/green gray
11127 (red filter on left eye, green filter on right eye)
11130 anaglyph red/cyan gray
11131 (red filter on left eye, cyan filter on right eye)
11134 anaglyph red/cyan half colored
11135 (red filter on left eye, cyan filter on right eye)
11138 anaglyph red/cyan color
11139 (red filter on left eye, cyan filter on right eye)
11142 anaglyph red/cyan color optimized with the least squares projection of dubois
11143 (red filter on left eye, cyan filter on right eye)
11146 anaglyph green/magenta gray
11147 (green filter on left eye, magenta filter on right eye)
11150 anaglyph green/magenta half colored
11151 (green filter on left eye, magenta filter on right eye)
11154 anaglyph green/magenta colored
11155 (green filter on left eye, magenta filter on right eye)
11158 anaglyph green/magenta color optimized with the least squares projection of dubois
11159 (green filter on left eye, magenta filter on right eye)
11162 anaglyph yellow/blue gray
11163 (yellow filter on left eye, blue filter on right eye)
11166 anaglyph yellow/blue half colored
11167 (yellow filter on left eye, blue filter on right eye)
11170 anaglyph yellow/blue colored
11171 (yellow filter on left eye, blue filter on right eye)
11174 anaglyph yellow/blue color optimized with the least squares projection of dubois
11175 (yellow filter on left eye, blue filter on right eye)
11178 mono output (left eye only)
11181 mono output (right eye only)
11184 checkerboard, left eye first
11187 checkerboard, right eye first
11190 interleaved columns, left eye first
11193 interleaved columns, right eye first
11196 Default value is @samp{arcd}.
11199 @subsection Examples
11203 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
11209 Convert input video from above below (left eye above, right eye below) to side by side crosseye.
11218 Apply a simple postprocessing filter that compresses and decompresses the image
11219 at several (or - in the case of @option{quality} level @code{6} - all) shifts
11220 and average the results.
11222 The filter accepts the following options:
11226 Set quality. This option defines the number of levels for averaging. It accepts
11227 an integer in the range 0-6. If set to @code{0}, the filter will have no
11228 effect. A value of @code{6} means the higher quality. For each increment of
11229 that value the speed drops by a factor of approximately 2. Default value is
11233 Force a constant quantization parameter. If not set, the filter will use the QP
11234 from the video stream (if available).
11237 Set thresholding mode. Available modes are:
11241 Set hard thresholding (default).
11243 Set soft thresholding (better de-ringing effect, but likely blurrier).
11246 @item use_bframe_qp
11247 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
11248 option may cause flicker since the B-Frames have often larger QP. Default is
11249 @code{0} (not enabled).
11255 Draw subtitles on top of input video using the libass library.
11257 To enable compilation of this filter you need to configure FFmpeg with
11258 @code{--enable-libass}. This filter also requires a build with libavcodec and
11259 libavformat to convert the passed subtitles file to ASS (Advanced Substation
11260 Alpha) subtitles format.
11262 The filter accepts the following options:
11266 Set the filename of the subtitle file to read. It must be specified.
11268 @item original_size
11269 Specify the size of the original video, the video for which the ASS file
11270 was composed. For the syntax of this option, check the
11271 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11272 Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
11273 correctly scale the fonts if the aspect ratio has been changed.
11276 Set a directory path containing fonts that can be used by the filter.
11277 These fonts will be used in addition to whatever the font provider uses.
11280 Set subtitles input character encoding. @code{subtitles} filter only. Only
11281 useful if not UTF-8.
11283 @item stream_index, si
11284 Set subtitles stream index. @code{subtitles} filter only.
11287 Override default style or script info parameters of the subtitles. It accepts a
11288 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
11291 If the first key is not specified, it is assumed that the first value
11292 specifies the @option{filename}.
11294 For example, to render the file @file{sub.srt} on top of the input
11295 video, use the command:
11300 which is equivalent to:
11302 subtitles=filename=sub.srt
11305 To render the default subtitles stream from file @file{video.mkv}, use:
11307 subtitles=video.mkv
11310 To render the second subtitles stream from that file, use:
11312 subtitles=video.mkv:si=1
11315 To make the subtitles stream from @file{sub.srt} appear in transparent green
11316 @code{DejaVu Serif}, use:
11318 subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
11321 @section super2xsai
11323 Scale the input by 2x and smooth using the Super2xSaI (Scale and
11324 Interpolate) pixel art scaling algorithm.
11326 Useful for enlarging pixel art images without reducing sharpness.
11333 Apply telecine process to the video.
11335 This filter accepts the following options:
11344 The default value is @code{top}.
11348 A string of numbers representing the pulldown pattern you wish to apply.
11349 The default value is @code{23}.
11353 Some typical patterns:
11358 24p: 2332 (preferred)
11365 24p: 222222222223 ("Euro pulldown")
11371 Select the most representative frame in a given sequence of consecutive frames.
11373 The filter accepts the following options:
11377 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
11378 will pick one of them, and then handle the next batch of @var{n} frames until
11379 the end. Default is @code{100}.
11382 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
11383 value will result in a higher memory usage, so a high value is not recommended.
11385 @subsection Examples
11389 Extract one picture each 50 frames:
11395 Complete example of a thumbnail creation with @command{ffmpeg}:
11397 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
11403 Tile several successive frames together.
11405 The filter accepts the following options:
11410 Set the grid size (i.e. the number of lines and columns). For the syntax of
11411 this option, check the
11412 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11415 Set the maximum number of frames to render in the given area. It must be less
11416 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
11417 the area will be used.
11420 Set the outer border margin in pixels.
11423 Set the inner border thickness (i.e. the number of pixels between frames). For
11424 more advanced padding options (such as having different values for the edges),
11425 refer to the pad video filter.
11428 Specify the color of the unused area. For the syntax of this option, check the
11429 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
11433 @subsection Examples
11437 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
11439 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
11441 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
11442 duplicating each output frame to accommodate the originally detected frame
11446 Display @code{5} pictures in an area of @code{3x2} frames,
11447 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
11448 mixed flat and named options:
11450 tile=3x2:nb_frames=5:padding=7:margin=2
11454 @section tinterlace
11456 Perform various types of temporal field interlacing.
11458 Frames are counted starting from 1, so the first input frame is
11461 The filter accepts the following options:
11466 Specify the mode of the interlacing. This option can also be specified
11467 as a value alone. See below for a list of values for this option.
11469 Available values are:
11473 Move odd frames into the upper field, even into the lower field,
11474 generating a double height frame at half frame rate.
11478 Frame 1 Frame 2 Frame 3 Frame 4
11480 11111 22222 33333 44444
11481 11111 22222 33333 44444
11482 11111 22222 33333 44444
11483 11111 22222 33333 44444
11497 Only output even frames, odd frames are dropped, generating a frame with
11498 unchanged height at half frame rate.
11503 Frame 1 Frame 2 Frame 3 Frame 4
11505 11111 22222 33333 44444
11506 11111 22222 33333 44444
11507 11111 22222 33333 44444
11508 11111 22222 33333 44444
11518 Only output odd frames, even frames are dropped, generating a frame with
11519 unchanged height at half frame rate.
11524 Frame 1 Frame 2 Frame 3 Frame 4
11526 11111 22222 33333 44444
11527 11111 22222 33333 44444
11528 11111 22222 33333 44444
11529 11111 22222 33333 44444
11539 Expand each frame to full height, but pad alternate lines with black,
11540 generating a frame with double height at the same input frame rate.
11545 Frame 1 Frame 2 Frame 3 Frame 4
11547 11111 22222 33333 44444
11548 11111 22222 33333 44444
11549 11111 22222 33333 44444
11550 11111 22222 33333 44444
11553 11111 ..... 33333 .....
11554 ..... 22222 ..... 44444
11555 11111 ..... 33333 .....
11556 ..... 22222 ..... 44444
11557 11111 ..... 33333 .....
11558 ..... 22222 ..... 44444
11559 11111 ..... 33333 .....
11560 ..... 22222 ..... 44444
11564 @item interleave_top, 4
11565 Interleave the upper field from odd frames with the lower field from
11566 even frames, generating a frame with unchanged height at half frame rate.
11571 Frame 1 Frame 2 Frame 3 Frame 4
11573 11111<- 22222 33333<- 44444
11574 11111 22222<- 33333 44444<-
11575 11111<- 22222 33333<- 44444
11576 11111 22222<- 33333 44444<-
11586 @item interleave_bottom, 5
11587 Interleave the lower field from odd frames with the upper field from
11588 even frames, generating a frame with unchanged height at half frame rate.
11593 Frame 1 Frame 2 Frame 3 Frame 4
11595 11111 22222<- 33333 44444<-
11596 11111<- 22222 33333<- 44444
11597 11111 22222<- 33333 44444<-
11598 11111<- 22222 33333<- 44444
11608 @item interlacex2, 6
11609 Double frame rate with unchanged height. Frames are inserted each
11610 containing the second temporal field from the previous input frame and
11611 the first temporal field from the next input frame. This mode relies on
11612 the top_field_first flag. Useful for interlaced video displays with no
11613 field synchronisation.
11618 Frame 1 Frame 2 Frame 3 Frame 4
11620 11111 22222 33333 44444
11621 11111 22222 33333 44444
11622 11111 22222 33333 44444
11623 11111 22222 33333 44444
11626 11111 22222 22222 33333 33333 44444 44444
11627 11111 11111 22222 22222 33333 33333 44444
11628 11111 22222 22222 33333 33333 44444 44444
11629 11111 11111 22222 22222 33333 33333 44444
11633 Move odd frames into the upper field, even into the lower field,
11634 generating a double height frame at same frame rate.
11638 Frame 1 Frame 2 Frame 3 Frame 4
11640 11111 22222 33333 44444
11641 11111 22222 33333 44444
11642 11111 22222 33333 44444
11643 11111 22222 33333 44444
11646 11111 33333 33333 55555
11647 22222 22222 44444 44444
11648 11111 33333 33333 55555
11649 22222 22222 44444 44444
11650 11111 33333 33333 55555
11651 22222 22222 44444 44444
11652 11111 33333 33333 55555
11653 22222 22222 44444 44444
11658 Numeric values are deprecated but are accepted for backward
11659 compatibility reasons.
11661 Default mode is @code{merge}.
11664 Specify flags influencing the filter process.
11666 Available value for @var{flags} is:
11669 @item low_pass_filter, vlfp
11670 Enable vertical low-pass filtering in the filter.
11671 Vertical low-pass filtering is required when creating an interlaced
11672 destination from a progressive source which contains high-frequency
11673 vertical detail. Filtering will reduce interlace 'twitter' and Moire
11676 Vertical low-pass filtering can only be enabled for @option{mode}
11677 @var{interleave_top} and @var{interleave_bottom}.
11684 Transpose rows with columns in the input video and optionally flip it.
11686 It accepts the following parameters:
11691 Specify the transposition direction.
11693 Can assume the following values:
11695 @item 0, 4, cclock_flip
11696 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
11704 Rotate by 90 degrees clockwise, that is:
11712 Rotate by 90 degrees counterclockwise, that is:
11719 @item 3, 7, clock_flip
11720 Rotate by 90 degrees clockwise and vertically flip, that is:
11728 For values between 4-7, the transposition is only done if the input
11729 video geometry is portrait and not landscape. These values are
11730 deprecated, the @code{passthrough} option should be used instead.
11732 Numerical values are deprecated, and should be dropped in favor of
11733 symbolic constants.
11736 Do not apply the transposition if the input geometry matches the one
11737 specified by the specified value. It accepts the following values:
11740 Always apply transposition.
11742 Preserve portrait geometry (when @var{height} >= @var{width}).
11744 Preserve landscape geometry (when @var{width} >= @var{height}).
11747 Default value is @code{none}.
11750 For example to rotate by 90 degrees clockwise and preserve portrait
11753 transpose=dir=1:passthrough=portrait
11756 The command above can also be specified as:
11758 transpose=1:portrait
11762 Trim the input so that the output contains one continuous subpart of the input.
11764 It accepts the following parameters:
11767 Specify the time of the start of the kept section, i.e. the frame with the
11768 timestamp @var{start} will be the first frame in the output.
11771 Specify the time of the first frame that will be dropped, i.e. the frame
11772 immediately preceding the one with the timestamp @var{end} will be the last
11773 frame in the output.
11776 This is the same as @var{start}, except this option sets the start timestamp
11777 in timebase units instead of seconds.
11780 This is the same as @var{end}, except this option sets the end timestamp
11781 in timebase units instead of seconds.
11784 The maximum duration of the output in seconds.
11787 The number of the first frame that should be passed to the output.
11790 The number of the first frame that should be dropped.
11793 @option{start}, @option{end}, and @option{duration} are expressed as time
11794 duration specifications; see
11795 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
11796 for the accepted syntax.
11798 Note that the first two sets of the start/end options and the @option{duration}
11799 option look at the frame timestamp, while the _frame variants simply count the
11800 frames that pass through the filter. Also note that this filter does not modify
11801 the timestamps. If you wish for the output timestamps to start at zero, insert a
11802 setpts filter after the trim filter.
11804 If multiple start or end options are set, this filter tries to be greedy and
11805 keep all the frames that match at least one of the specified constraints. To keep
11806 only the part that matches all the constraints at once, chain multiple trim
11809 The defaults are such that all the input is kept. So it is possible to set e.g.
11810 just the end values to keep everything before the specified time.
11815 Drop everything except the second minute of input:
11817 ffmpeg -i INPUT -vf trim=60:120
11821 Keep only the first second:
11823 ffmpeg -i INPUT -vf trim=duration=1
11832 Sharpen or blur the input video.
11834 It accepts the following parameters:
11837 @item luma_msize_x, lx
11838 Set the luma matrix horizontal size. It must be an odd integer between
11839 3 and 63. The default value is 5.
11841 @item luma_msize_y, ly
11842 Set the luma matrix vertical size. It must be an odd integer between 3
11843 and 63. The default value is 5.
11845 @item luma_amount, la
11846 Set the luma effect strength. It must be a floating point number, reasonable
11847 values lay between -1.5 and 1.5.
11849 Negative values will blur the input video, while positive values will
11850 sharpen it, a value of zero will disable the effect.
11852 Default value is 1.0.
11854 @item chroma_msize_x, cx
11855 Set the chroma matrix horizontal size. It must be an odd integer
11856 between 3 and 63. The default value is 5.
11858 @item chroma_msize_y, cy
11859 Set the chroma matrix vertical size. It must be an odd integer
11860 between 3 and 63. The default value is 5.
11862 @item chroma_amount, ca
11863 Set the chroma effect strength. It must be a floating point number, reasonable
11864 values lay between -1.5 and 1.5.
11866 Negative values will blur the input video, while positive values will
11867 sharpen it, a value of zero will disable the effect.
11869 Default value is 0.0.
11872 If set to 1, specify using OpenCL capabilities, only available if
11873 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
11877 All parameters are optional and default to the equivalent of the
11878 string '5:5:1.0:5:5:0.0'.
11880 @subsection Examples
11884 Apply strong luma sharpen effect:
11886 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
11890 Apply a strong blur of both luma and chroma parameters:
11892 unsharp=7:7:-2:7:7:-2
11898 Apply ultra slow/simple postprocessing filter that compresses and decompresses
11899 the image at several (or - in the case of @option{quality} level @code{8} - all)
11900 shifts and average the results.
11902 The way this differs from the behavior of spp is that uspp actually encodes &
11903 decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
11904 DCT similar to MJPEG.
11906 The filter accepts the following options:
11910 Set quality. This option defines the number of levels for averaging. It accepts
11911 an integer in the range 0-8. If set to @code{0}, the filter will have no
11912 effect. A value of @code{8} means the higher quality. For each increment of
11913 that value the speed drops by a factor of approximately 2. Default value is
11917 Force a constant quantization parameter. If not set, the filter will use the QP
11918 from the video stream (if available).
11921 @section vectorscope
11923 Display 2 color component values in the two dimensional graph (which is called
11926 This filter accepts the following options:
11930 Set vectorscope mode.
11932 It accepts the following values:
11935 Gray values are displayed on graph, higher brightness means more pixels have
11936 same component color value on location in graph. This is the default mode.
11939 Gray values are displayed on graph. Surrounding pixels values which are not
11940 present in video frame are drawn in gradient of 2 color components which are
11941 set by option @code{x} and @code{y}.
11944 Actual color components values present in video frame are displayed on graph.
11947 Similar as color2 but higher frequency of same values @code{x} and @code{y}
11948 on graph increases value of another color component, which is luminance by
11949 default values of @code{x} and @code{y}.
11952 Actual colors present in video frame are displayed on graph. If two different
11953 colors map to same position on graph then color with higher value of component
11954 not present in graph is picked.
11958 Set which color component will be represented on X-axis. Default is @code{1}.
11961 Set which color component will be represented on Y-axis. Default is @code{2}.
11964 Set intensity, used by modes: gray, color and color3 for increasing brightness
11965 of color component which represents frequency of (X, Y) location in graph.
11970 No envelope, this is default.
11973 Instant envelope, even darkest single pixel will be clearly highlighted.
11976 Hold maximum and minimum values presented in graph over time. This way you
11977 can still spot out of range values without constantly looking at vectorscope.
11980 Peak and instant envelope combined together.
11984 @anchor{vidstabdetect}
11985 @section vidstabdetect
11987 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
11988 @ref{vidstabtransform} for pass 2.
11990 This filter generates a file with relative translation and rotation
11991 transform information about subsequent frames, which is then used by
11992 the @ref{vidstabtransform} filter.
11994 To enable compilation of this filter you need to configure FFmpeg with
11995 @code{--enable-libvidstab}.
11997 This filter accepts the following options:
12001 Set the path to the file used to write the transforms information.
12002 Default value is @file{transforms.trf}.
12005 Set how shaky the video is and how quick the camera is. It accepts an
12006 integer in the range 1-10, a value of 1 means little shakiness, a
12007 value of 10 means strong shakiness. Default value is 5.
12010 Set the accuracy of the detection process. It must be a value in the
12011 range 1-15. A value of 1 means low accuracy, a value of 15 means high
12012 accuracy. Default value is 15.
12015 Set stepsize of the search process. The region around minimum is
12016 scanned with 1 pixel resolution. Default value is 6.
12019 Set minimum contrast. Below this value a local measurement field is
12020 discarded. Must be a floating point value in the range 0-1. Default
12024 Set reference frame number for tripod mode.
12026 If enabled, the motion of the frames is compared to a reference frame
12027 in the filtered stream, identified by the specified number. The idea
12028 is to compensate all movements in a more-or-less static scene and keep
12029 the camera view absolutely still.
12031 If set to 0, it is disabled. The frames are counted starting from 1.
12034 Show fields and transforms in the resulting frames. It accepts an
12035 integer in the range 0-2. Default value is 0, which disables any
12039 @subsection Examples
12043 Use default values:
12049 Analyze strongly shaky movie and put the results in file
12050 @file{mytransforms.trf}:
12052 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
12056 Visualize the result of internal transformations in the resulting
12059 vidstabdetect=show=1
12063 Analyze a video with medium shakiness using @command{ffmpeg}:
12065 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
12069 @anchor{vidstabtransform}
12070 @section vidstabtransform
12072 Video stabilization/deshaking: pass 2 of 2,
12073 see @ref{vidstabdetect} for pass 1.
12075 Read a file with transform information for each frame and
12076 apply/compensate them. Together with the @ref{vidstabdetect}
12077 filter this can be used to deshake videos. See also
12078 @url{http://public.hronopik.de/vid.stab}. It is important to also use
12079 the @ref{unsharp} filter, see below.
12081 To enable compilation of this filter you need to configure FFmpeg with
12082 @code{--enable-libvidstab}.
12084 @subsection Options
12088 Set path to the file used to read the transforms. Default value is
12089 @file{transforms.trf}.
12092 Set the number of frames (value*2 + 1) used for lowpass filtering the
12093 camera movements. Default value is 10.
12095 For example a number of 10 means that 21 frames are used (10 in the
12096 past and 10 in the future) to smoothen the motion in the video. A
12097 larger value leads to a smoother video, but limits the acceleration of
12098 the camera (pan/tilt movements). 0 is a special case where a static
12099 camera is simulated.
12102 Set the camera path optimization algorithm.
12104 Accepted values are:
12107 gaussian kernel low-pass filter on camera motion (default)
12109 averaging on transformations
12113 Set maximal number of pixels to translate frames. Default value is -1,
12117 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
12118 value is -1, meaning no limit.
12121 Specify how to deal with borders that may be visible due to movement
12124 Available values are:
12127 keep image information from previous frame (default)
12129 fill the border black
12133 Invert transforms if set to 1. Default value is 0.
12136 Consider transforms as relative to previous frame if set to 1,
12137 absolute if set to 0. Default value is 0.
12140 Set percentage to zoom. A positive value will result in a zoom-in
12141 effect, a negative value in a zoom-out effect. Default value is 0 (no
12145 Set optimal zooming to avoid borders.
12147 Accepted values are:
12152 optimal static zoom value is determined (only very strong movements
12153 will lead to visible borders) (default)
12155 optimal adaptive zoom value is determined (no borders will be
12156 visible), see @option{zoomspeed}
12159 Note that the value given at zoom is added to the one calculated here.
12162 Set percent to zoom maximally each frame (enabled when
12163 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
12167 Specify type of interpolation.
12169 Available values are:
12174 linear only horizontal
12176 linear in both directions (default)
12178 cubic in both directions (slow)
12182 Enable virtual tripod mode if set to 1, which is equivalent to
12183 @code{relative=0:smoothing=0}. Default value is 0.
12185 Use also @code{tripod} option of @ref{vidstabdetect}.
12188 Increase log verbosity if set to 1. Also the detected global motions
12189 are written to the temporary file @file{global_motions.trf}. Default
12193 @subsection Examples
12197 Use @command{ffmpeg} for a typical stabilization with default values:
12199 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
12202 Note the use of the @ref{unsharp} filter which is always recommended.
12205 Zoom in a bit more and load transform data from a given file:
12207 vidstabtransform=zoom=5:input="mytransforms.trf"
12211 Smoothen the video even more:
12213 vidstabtransform=smoothing=30
12219 Flip the input video vertically.
12221 For example, to vertically flip a video with @command{ffmpeg}:
12223 ffmpeg -i in.avi -vf "vflip" out.avi
12229 Make or reverse a natural vignetting effect.
12231 The filter accepts the following options:
12235 Set lens angle expression as a number of radians.
12237 The value is clipped in the @code{[0,PI/2]} range.
12239 Default value: @code{"PI/5"}
12243 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
12247 Set forward/backward mode.
12249 Available modes are:
12252 The larger the distance from the central point, the darker the image becomes.
12255 The larger the distance from the central point, the brighter the image becomes.
12256 This can be used to reverse a vignette effect, though there is no automatic
12257 detection to extract the lens @option{angle} and other settings (yet). It can
12258 also be used to create a burning effect.
12261 Default value is @samp{forward}.
12264 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
12266 It accepts the following values:
12269 Evaluate expressions only once during the filter initialization.
12272 Evaluate expressions for each incoming frame. This is way slower than the
12273 @samp{init} mode since it requires all the scalers to be re-computed, but it
12274 allows advanced dynamic expressions.
12277 Default value is @samp{init}.
12280 Set dithering to reduce the circular banding effects. Default is @code{1}
12284 Set vignette aspect. This setting allows one to adjust the shape of the vignette.
12285 Setting this value to the SAR of the input will make a rectangular vignetting
12286 following the dimensions of the video.
12288 Default is @code{1/1}.
12291 @subsection Expressions
12293 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
12294 following parameters.
12299 input width and height
12302 the number of input frame, starting from 0
12305 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
12306 @var{TB} units, NAN if undefined
12309 frame rate of the input video, NAN if the input frame rate is unknown
12312 the PTS (Presentation TimeStamp) of the filtered video frame,
12313 expressed in seconds, NAN if undefined
12316 time base of the input video
12320 @subsection Examples
12324 Apply simple strong vignetting effect:
12330 Make a flickering vignetting:
12332 vignette='PI/4+random(1)*PI/50':eval=frame
12338 Stack input videos vertically.
12340 All streams must be of same pixel format and of same width.
12342 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
12343 to create same output.
12345 The filter accept the following option:
12349 Set number of input streams. Default is 2.
12352 If set to 1, force the output to terminate when the shortest input
12353 terminates. Default value is 0.
12358 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
12359 Deinterlacing Filter").
12361 Based on the process described by Martin Weston for BBC R&D, and
12362 implemented based on the de-interlace algorithm written by Jim
12363 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
12364 uses filter coefficients calculated by BBC R&D.
12366 There are two sets of filter coefficients, so called "simple":
12367 and "complex". Which set of filter coefficients is used can
12368 be set by passing an optional parameter:
12372 Set the interlacing filter coefficients. Accepts one of the following values:
12376 Simple filter coefficient set.
12378 More-complex filter coefficient set.
12380 Default value is @samp{complex}.
12383 Specify which frames to deinterlace. Accept one of the following values:
12387 Deinterlace all frames,
12389 Only deinterlace frames marked as interlaced.
12392 Default value is @samp{all}.
12396 Video waveform monitor.
12398 The waveform monitor plots color component intensity. By default luminance
12399 only. Each column of the waveform corresponds to a column of pixels in the
12402 It accepts the following options:
12406 Can be either @code{row}, or @code{column}. Default is @code{column}.
12407 In row mode, the graph on the left side represents color component value 0 and
12408 the right side represents value = 255. In column mode, the top side represents
12409 color component value = 0 and bottom side represents value = 255.
12412 Set intensity. Smaller values are useful to find out how many values of the same
12413 luminance are distributed across input rows/columns.
12414 Default value is @code{0.04}. Allowed range is [0, 1].
12417 Set mirroring mode. @code{0} means unmirrored, @code{1} means mirrored.
12418 In mirrored mode, higher values will be represented on the left
12419 side for @code{row} mode and at the top for @code{column} mode. Default is
12420 @code{1} (mirrored).
12424 It accepts the following values:
12427 Presents information identical to that in the @code{parade}, except
12428 that the graphs representing color components are superimposed directly
12431 This display mode makes it easier to spot relative differences or similarities
12432 in overlapping areas of the color components that are supposed to be identical,
12433 such as neutral whites, grays, or blacks.
12436 Display separate graph for the color components side by side in
12437 @code{row} mode or one below the other in @code{column} mode.
12439 Using this display mode makes it easy to spot color casts in the highlights
12440 and shadows of an image, by comparing the contours of the top and the bottom
12441 graphs of each waveform. Since whites, grays, and blacks are characterized
12442 by exactly equal amounts of red, green, and blue, neutral areas of the picture
12443 should display three waveforms of roughly equal width/height. If not, the
12444 correction is easy to perform by making level adjustments the three waveforms.
12446 Default is @code{parade}.
12448 @item components, c
12449 Set which color components to display. Default is 1, which means only luminance
12450 or red color component if input is in RGB colorspace. If is set for example to
12451 7 it will display all 3 (if) available color components.
12456 No envelope, this is default.
12459 Instant envelope, minimum and maximum values presented in graph will be easily
12460 visible even with small @code{step} value.
12463 Hold minimum and maximum values presented in graph across time. This way you
12464 can still spot out of range values without constantly looking at waveforms.
12467 Peak and instant envelope combined together.
12473 No filtering, this is default.
12476 Luma and chroma combined together.
12479 Similar as above, but shows difference between blue and red chroma.
12482 Displays only chroma.
12485 Similar as above, but shows difference between blue and red chroma.
12488 Displays actual color value on waveform.
12493 Apply the xBR high-quality magnification filter which is designed for pixel
12494 art. It follows a set of edge-detection rules, see
12495 @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}.
12497 It accepts the following option:
12501 Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
12502 @code{3xBR} and @code{4} for @code{4xBR}.
12503 Default is @code{3}.
12509 Deinterlace the input video ("yadif" means "yet another deinterlacing
12512 It accepts the following parameters:
12518 The interlacing mode to adopt. It accepts one of the following values:
12521 @item 0, send_frame
12522 Output one frame for each frame.
12523 @item 1, send_field
12524 Output one frame for each field.
12525 @item 2, send_frame_nospatial
12526 Like @code{send_frame}, but it skips the spatial interlacing check.
12527 @item 3, send_field_nospatial
12528 Like @code{send_field}, but it skips the spatial interlacing check.
12531 The default value is @code{send_frame}.
12534 The picture field parity assumed for the input interlaced video. It accepts one
12535 of the following values:
12539 Assume the top field is first.
12541 Assume the bottom field is first.
12543 Enable automatic detection of field parity.
12546 The default value is @code{auto}.
12547 If the interlacing is unknown or the decoder does not export this information,
12548 top field first will be assumed.
12551 Specify which frames to deinterlace. Accept one of the following
12556 Deinterlace all frames.
12557 @item 1, interlaced
12558 Only deinterlace frames marked as interlaced.
12561 The default value is @code{all}.
12566 Apply Zoom & Pan effect.
12568 This filter accepts the following options:
12572 Set the zoom expression. Default is 1.
12576 Set the x and y expression. Default is 0.
12579 Set the duration expression in number of frames.
12580 This sets for how many number of frames effect will last for
12581 single input image.
12584 Set the output image size, default is 'hd720'.
12587 Set the output frame rate, default is '25'.
12590 Each expression can contain the following constants:
12609 Output frame count.
12613 Last calculated 'x' and 'y' position from 'x' and 'y' expression
12614 for current input frame.
12618 'x' and 'y' of last output frame of previous input frame or 0 when there was
12619 not yet such frame (first input frame).
12622 Last calculated zoom from 'z' expression for current input frame.
12625 Last calculated zoom of last output frame of previous input frame.
12628 Number of output frames for current input frame. Calculated from 'd' expression
12629 for each input frame.
12632 number of output frames created for previous input frame
12635 Rational number: input width / input height
12638 sample aspect ratio
12641 display aspect ratio
12645 @subsection Examples
12649 Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
12651 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
12655 Zoom-in up to 1.5 and pan always at center of picture:
12657 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
12662 Scale (resize) the input video, using the z.lib library:
12663 https://github.com/sekrit-twc/zimg.
12665 The zscale filter forces the output display aspect ratio to be the same
12666 as the input, by changing the output sample aspect ratio.
12668 If the input image format is different from the format requested by
12669 the next filter, the zscale filter will convert the input to the
12672 @subsection Options
12673 The filter accepts the following options.
12678 Set the output video dimension expression. Default value is the input
12681 If the @var{width} or @var{w} is 0, the input width is used for the output.
12682 If the @var{height} or @var{h} is 0, the input height is used for the output.
12684 If one of the values is -1, the zscale filter will use a value that
12685 maintains the aspect ratio of the input image, calculated from the
12686 other specified dimension. If both of them are -1, the input size is
12689 If one of the values is -n with n > 1, the zscale filter will also use a value
12690 that maintains the aspect ratio of the input image, calculated from the other
12691 specified dimension. After that it will, however, make sure that the calculated
12692 dimension is divisible by n and adjust the value if necessary.
12694 See below for the list of accepted constants for use in the dimension
12698 Set the video size. For the syntax of this option, check the
12699 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12702 Set the dither type.
12704 Possible values are:
12709 @item error_diffusion
12715 Set the resize filter type.
12717 Possible values are:
12727 Default is bilinear.
12730 Set the color range.
12732 Possible values are:
12739 Default is same as input.
12742 Set the color primaries.
12744 Possible values are:
12754 Default is same as input.
12757 Set the transfer characteristics.
12759 Possible values are:
12770 Default is same as input.
12773 Set the colorspace matrix.
12775 Possible value are:
12786 Default is same as input.
12789 Set the input color range.
12791 Possible values are:
12798 Default is same as input.
12800 @item primariesin, pin
12801 Set the input color primaries.
12803 Possible values are:
12813 Default is same as input.
12815 @item transferin, tin
12816 Set the input transfer characteristics.
12818 Possible values are:
12829 Default is same as input.
12831 @item matrixin, min
12832 Set the input colorspace matrix.
12834 Possible value are:
12846 The values of the @option{w} and @option{h} options are expressions
12847 containing the following constants:
12852 The input width and height
12856 These are the same as @var{in_w} and @var{in_h}.
12860 The output (scaled) width and height
12864 These are the same as @var{out_w} and @var{out_h}
12867 The same as @var{iw} / @var{ih}
12870 input sample aspect ratio
12873 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
12877 horizontal and vertical input chroma subsample values. For example for the
12878 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
12882 horizontal and vertical output chroma subsample values. For example for the
12883 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
12889 @c man end VIDEO FILTERS
12891 @chapter Video Sources
12892 @c man begin VIDEO SOURCES
12894 Below is a description of the currently available video sources.
12898 Buffer video frames, and make them available to the filter chain.
12900 This source is mainly intended for a programmatic use, in particular
12901 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
12903 It accepts the following parameters:
12908 Specify the size (width and height) of the buffered video frames. For the
12909 syntax of this option, check the
12910 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12913 The input video width.
12916 The input video height.
12919 A string representing the pixel format of the buffered video frames.
12920 It may be a number corresponding to a pixel format, or a pixel format
12924 Specify the timebase assumed by the timestamps of the buffered frames.
12927 Specify the frame rate expected for the video stream.
12929 @item pixel_aspect, sar
12930 The sample (pixel) aspect ratio of the input video.
12933 Specify the optional parameters to be used for the scale filter which
12934 is automatically inserted when an input change is detected in the
12935 input size or format.
12940 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
12943 will instruct the source to accept video frames with size 320x240 and
12944 with format "yuv410p", assuming 1/24 as the timestamps timebase and
12945 square pixels (1:1 sample aspect ratio).
12946 Since the pixel format with name "yuv410p" corresponds to the number 6
12947 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
12948 this example corresponds to:
12950 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
12953 Alternatively, the options can be specified as a flat string, but this
12954 syntax is deprecated:
12956 @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}]
12960 Create a pattern generated by an elementary cellular automaton.
12962 The initial state of the cellular automaton can be defined through the
12963 @option{filename}, and @option{pattern} options. If such options are
12964 not specified an initial state is created randomly.
12966 At each new frame a new row in the video is filled with the result of
12967 the cellular automaton next generation. The behavior when the whole
12968 frame is filled is defined by the @option{scroll} option.
12970 This source accepts the following options:
12974 Read the initial cellular automaton state, i.e. the starting row, from
12975 the specified file.
12976 In the file, each non-whitespace character is considered an alive
12977 cell, a newline will terminate the row, and further characters in the
12978 file will be ignored.
12981 Read the initial cellular automaton state, i.e. the starting row, from
12982 the specified string.
12984 Each non-whitespace character in the string is considered an alive
12985 cell, a newline will terminate the row, and further characters in the
12986 string will be ignored.
12989 Set the video rate, that is the number of frames generated per second.
12992 @item random_fill_ratio, ratio
12993 Set the random fill ratio for the initial cellular automaton row. It
12994 is a floating point number value ranging from 0 to 1, defaults to
12997 This option is ignored when a file or a pattern is specified.
12999 @item random_seed, seed
13000 Set the seed for filling randomly the initial row, must be an integer
13001 included between 0 and UINT32_MAX. If not specified, or if explicitly
13002 set to -1, the filter will try to use a good random seed on a best
13006 Set the cellular automaton rule, it is a number ranging from 0 to 255.
13007 Default value is 110.
13010 Set the size of the output video. For the syntax of this option, check the
13011 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13013 If @option{filename} or @option{pattern} is specified, the size is set
13014 by default to the width of the specified initial state row, and the
13015 height is set to @var{width} * PHI.
13017 If @option{size} is set, it must contain the width of the specified
13018 pattern string, and the specified pattern will be centered in the
13021 If a filename or a pattern string is not specified, the size value
13022 defaults to "320x518" (used for a randomly generated initial state).
13025 If set to 1, scroll the output upward when all the rows in the output
13026 have been already filled. If set to 0, the new generated row will be
13027 written over the top row just after the bottom row is filled.
13030 @item start_full, full
13031 If set to 1, completely fill the output with generated rows before
13032 outputting the first frame.
13033 This is the default behavior, for disabling set the value to 0.
13036 If set to 1, stitch the left and right row edges together.
13037 This is the default behavior, for disabling set the value to 0.
13040 @subsection Examples
13044 Read the initial state from @file{pattern}, and specify an output of
13047 cellauto=f=pattern:s=200x400
13051 Generate a random initial row with a width of 200 cells, with a fill
13054 cellauto=ratio=2/3:s=200x200
13058 Create a pattern generated by rule 18 starting by a single alive cell
13059 centered on an initial row with width 100:
13061 cellauto=p=@@:s=100x400:full=0:rule=18
13065 Specify a more elaborated initial pattern:
13067 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
13072 @section mandelbrot
13074 Generate a Mandelbrot set fractal, and progressively zoom towards the
13075 point specified with @var{start_x} and @var{start_y}.
13077 This source accepts the following options:
13082 Set the terminal pts value. Default value is 400.
13085 Set the terminal scale value.
13086 Must be a floating point value. Default value is 0.3.
13089 Set the inner coloring mode, that is the algorithm used to draw the
13090 Mandelbrot fractal internal region.
13092 It shall assume one of the following values:
13097 Show time until convergence.
13099 Set color based on point closest to the origin of the iterations.
13104 Default value is @var{mincol}.
13107 Set the bailout value. Default value is 10.0.
13110 Set the maximum of iterations performed by the rendering
13111 algorithm. Default value is 7189.
13114 Set outer coloring mode.
13115 It shall assume one of following values:
13117 @item iteration_count
13118 Set iteration cound mode.
13119 @item normalized_iteration_count
13120 set normalized iteration count mode.
13122 Default value is @var{normalized_iteration_count}.
13125 Set frame rate, expressed as number of frames per second. Default
13129 Set frame size. For the syntax of this option, check the "Video
13130 size" section in the ffmpeg-utils manual. Default value is "640x480".
13133 Set the initial scale value. Default value is 3.0.
13136 Set the initial x position. Must be a floating point value between
13137 -100 and 100. Default value is -0.743643887037158704752191506114774.
13140 Set the initial y position. Must be a floating point value between
13141 -100 and 100. Default value is -0.131825904205311970493132056385139.
13146 Generate various test patterns, as generated by the MPlayer test filter.
13148 The size of the generated video is fixed, and is 256x256.
13149 This source is useful in particular for testing encoding features.
13151 This source accepts the following options:
13156 Specify the frame rate of the sourced video, as the number of frames
13157 generated per second. It has to be a string in the format
13158 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
13159 number or a valid video frame rate abbreviation. The default value is
13163 Set the duration of the sourced video. See
13164 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
13165 for the accepted syntax.
13167 If not specified, or the expressed duration is negative, the video is
13168 supposed to be generated forever.
13172 Set the number or the name of the test to perform. Supported tests are:
13188 Default value is "all", which will cycle through the list of all tests.
13193 mptestsrc=t=dc_luma
13196 will generate a "dc_luma" test pattern.
13198 @section frei0r_src
13200 Provide a frei0r source.
13202 To enable compilation of this filter you need to install the frei0r
13203 header and configure FFmpeg with @code{--enable-frei0r}.
13205 This source accepts the following parameters:
13210 The size of the video to generate. For the syntax of this option, check the
13211 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13214 The framerate of the generated video. It may be a string of the form
13215 @var{num}/@var{den} or a frame rate abbreviation.
13218 The name to the frei0r source to load. For more information regarding frei0r and
13219 how to set the parameters, read the @ref{frei0r} section in the video filters
13222 @item filter_params
13223 A '|'-separated list of parameters to pass to the frei0r source.
13227 For example, to generate a frei0r partik0l source with size 200x200
13228 and frame rate 10 which is overlaid on the overlay filter main input:
13230 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
13235 Generate a life pattern.
13237 This source is based on a generalization of John Conway's life game.
13239 The sourced input represents a life grid, each pixel represents a cell
13240 which can be in one of two possible states, alive or dead. Every cell
13241 interacts with its eight neighbours, which are the cells that are
13242 horizontally, vertically, or diagonally adjacent.
13244 At each interaction the grid evolves according to the adopted rule,
13245 which specifies the number of neighbor alive cells which will make a
13246 cell stay alive or born. The @option{rule} option allows one to specify
13249 This source accepts the following options:
13253 Set the file from which to read the initial grid state. In the file,
13254 each non-whitespace character is considered an alive cell, and newline
13255 is used to delimit the end of each row.
13257 If this option is not specified, the initial grid is generated
13261 Set the video rate, that is the number of frames generated per second.
13264 @item random_fill_ratio, ratio
13265 Set the random fill ratio for the initial random grid. It is a
13266 floating point number value ranging from 0 to 1, defaults to 1/PHI.
13267 It is ignored when a file is specified.
13269 @item random_seed, seed
13270 Set the seed for filling the initial random grid, must be an integer
13271 included between 0 and UINT32_MAX. If not specified, or if explicitly
13272 set to -1, the filter will try to use a good random seed on a best
13278 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
13279 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
13280 @var{NS} specifies the number of alive neighbor cells which make a
13281 live cell stay alive, and @var{NB} the number of alive neighbor cells
13282 which make a dead cell to become alive (i.e. to "born").
13283 "s" and "b" can be used in place of "S" and "B", respectively.
13285 Alternatively a rule can be specified by an 18-bits integer. The 9
13286 high order bits are used to encode the next cell state if it is alive
13287 for each number of neighbor alive cells, the low order bits specify
13288 the rule for "borning" new cells. Higher order bits encode for an
13289 higher number of neighbor cells.
13290 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
13291 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
13293 Default value is "S23/B3", which is the original Conway's game of life
13294 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
13295 cells, and will born a new cell if there are three alive cells around
13299 Set the size of the output video. For the syntax of this option, check the
13300 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13302 If @option{filename} is specified, the size is set by default to the
13303 same size of the input file. If @option{size} is set, it must contain
13304 the size specified in the input file, and the initial grid defined in
13305 that file is centered in the larger resulting area.
13307 If a filename is not specified, the size value defaults to "320x240"
13308 (used for a randomly generated initial grid).
13311 If set to 1, stitch the left and right grid edges together, and the
13312 top and bottom edges also. Defaults to 1.
13315 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
13316 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
13317 value from 0 to 255.
13320 Set the color of living (or new born) cells.
13323 Set the color of dead cells. If @option{mold} is set, this is the first color
13324 used to represent a dead cell.
13327 Set mold color, for definitely dead and moldy cells.
13329 For the syntax of these 3 color options, check the "Color" section in the
13330 ffmpeg-utils manual.
13333 @subsection Examples
13337 Read a grid from @file{pattern}, and center it on a grid of size
13340 life=f=pattern:s=300x300
13344 Generate a random grid of size 200x200, with a fill ratio of 2/3:
13346 life=ratio=2/3:s=200x200
13350 Specify a custom rule for evolving a randomly generated grid:
13356 Full example with slow death effect (mold) using @command{ffplay}:
13358 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
13365 @anchor{haldclutsrc}
13367 @anchor{rgbtestsrc}
13369 @anchor{smptehdbars}
13371 @section allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
13373 The @code{allrgb} source returns frames of size 4096x4096 of all rgb colors.
13375 The @code{allyuv} source returns frames of size 4096x4096 of all yuv colors.
13377 The @code{color} source provides an uniformly colored input.
13379 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
13380 @ref{haldclut} filter.
13382 The @code{nullsrc} source returns unprocessed video frames. It is
13383 mainly useful to be employed in analysis / debugging tools, or as the
13384 source for filters which ignore the input data.
13386 The @code{rgbtestsrc} source generates an RGB test pattern useful for
13387 detecting RGB vs BGR issues. You should see a red, green and blue
13388 stripe from top to bottom.
13390 The @code{smptebars} source generates a color bars pattern, based on
13391 the SMPTE Engineering Guideline EG 1-1990.
13393 The @code{smptehdbars} source generates a color bars pattern, based on
13394 the SMPTE RP 219-2002.
13396 The @code{testsrc} source generates a test video pattern, showing a
13397 color pattern, a scrolling gradient and a timestamp. This is mainly
13398 intended for testing purposes.
13400 The sources accept the following parameters:
13405 Specify the color of the source, only available in the @code{color}
13406 source. For the syntax of this option, check the "Color" section in the
13407 ffmpeg-utils manual.
13410 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
13411 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
13412 pixels to be used as identity matrix for 3D lookup tables. Each component is
13413 coded on a @code{1/(N*N)} scale.
13416 Specify the size of the sourced video. For the syntax of this option, check the
13417 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13418 The default value is @code{320x240}.
13420 This option is not available with the @code{haldclutsrc} filter.
13423 Specify the frame rate of the sourced video, as the number of frames
13424 generated per second. It has to be a string in the format
13425 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
13426 number or a valid video frame rate abbreviation. The default value is
13430 Set the sample aspect ratio of the sourced video.
13433 Set the duration of the sourced video. See
13434 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
13435 for the accepted syntax.
13437 If not specified, or the expressed duration is negative, the video is
13438 supposed to be generated forever.
13441 Set the number of decimals to show in the timestamp, only available in the
13442 @code{testsrc} source.
13444 The displayed timestamp value will correspond to the original
13445 timestamp value multiplied by the power of 10 of the specified
13446 value. Default value is 0.
13449 For example the following:
13451 testsrc=duration=5.3:size=qcif:rate=10
13454 will generate a video with a duration of 5.3 seconds, with size
13455 176x144 and a frame rate of 10 frames per second.
13457 The following graph description will generate a red source
13458 with an opacity of 0.2, with size "qcif" and a frame rate of 10
13461 color=c=red@@0.2:s=qcif:r=10
13464 If the input content is to be ignored, @code{nullsrc} can be used. The
13465 following command generates noise in the luminance plane by employing
13466 the @code{geq} filter:
13468 nullsrc=s=256x256, geq=random(1)*255:128:128
13471 @subsection Commands
13473 The @code{color} source supports the following commands:
13477 Set the color of the created image. Accepts the same syntax of the
13478 corresponding @option{color} option.
13481 @c man end VIDEO SOURCES
13483 @chapter Video Sinks
13484 @c man begin VIDEO SINKS
13486 Below is a description of the currently available video sinks.
13488 @section buffersink
13490 Buffer video frames, and make them available to the end of the filter
13493 This sink is mainly intended for programmatic use, in particular
13494 through the interface defined in @file{libavfilter/buffersink.h}
13495 or the options system.
13497 It accepts a pointer to an AVBufferSinkContext structure, which
13498 defines the incoming buffers' formats, to be passed as the opaque
13499 parameter to @code{avfilter_init_filter} for initialization.
13503 Null video sink: do absolutely nothing with the input video. It is
13504 mainly useful as a template and for use in analysis / debugging
13507 @c man end VIDEO SINKS
13509 @chapter Multimedia Filters
13510 @c man begin MULTIMEDIA FILTERS
13512 Below is a description of the currently available multimedia filters.
13514 @section ahistogram
13516 Convert input audio to a video output, displaying the volume histogram.
13518 The filter accepts the following options:
13522 Specify how histogram is calculated.
13524 It accepts the following values:
13527 Use single histogram for all channels.
13529 Use separate histogram for each channel.
13531 Default is @code{single}.
13534 Set frame rate, expressed as number of frames per second. Default
13538 Specify the video size for the output. For the syntax of this option, check the
13539 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13540 Default value is @code{hd720}.
13545 It accepts the following values:
13556 reverse logarithmic
13558 Default is @code{log}.
13561 Set amplitude scale.
13563 It accepts the following values:
13570 Default is @code{log}.
13573 Set how much frames to accumulate in histogram.
13574 Defauls is 1. Setting this to -1 accumulates all frames.
13577 Set histogram ratio of window height.
13580 Set sonogram sliding.
13582 It accepts the following values:
13585 replace old rows with new ones.
13587 scroll from top to bottom.
13589 Default is @code{replace}.
13592 @section aphasemeter
13594 Convert input audio to a video output, displaying the audio phase.
13596 The filter accepts the following options:
13600 Set the output frame rate. Default value is @code{25}.
13603 Set the video size for the output. For the syntax of this option, check the
13604 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13605 Default value is @code{800x400}.
13610 Specify the red, green, blue contrast. Default values are @code{2},
13611 @code{7} and @code{1}.
13612 Allowed range is @code{[0, 255]}.
13615 Set color which will be used for drawing median phase. If color is
13616 @code{none} which is default, no median phase value will be drawn.
13619 The filter also exports the frame metadata @code{lavfi.aphasemeter.phase} which
13620 represents mean phase of current audio frame. Value is in range @code{[-1, 1]}.
13621 The @code{-1} means left and right channels are completely out of phase and
13622 @code{1} means channels are in phase.
13624 @section avectorscope
13626 Convert input audio to a video output, representing the audio vector
13629 The filter is used to measure the difference between channels of stereo
13630 audio stream. A monoaural signal, consisting of identical left and right
13631 signal, results in straight vertical line. Any stereo separation is visible
13632 as a deviation from this line, creating a Lissajous figure.
13633 If the straight (or deviation from it) but horizontal line appears this
13634 indicates that the left and right channels are out of phase.
13636 The filter accepts the following options:
13640 Set the vectorscope mode.
13642 Available values are:
13645 Lissajous rotated by 45 degrees.
13648 Same as above but not rotated.
13651 Shape resembling half of circle.
13654 Default value is @samp{lissajous}.
13657 Set the video size for the output. For the syntax of this option, check the
13658 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13659 Default value is @code{400x400}.
13662 Set the output frame rate. Default value is @code{25}.
13668 Specify the red, green, blue and alpha contrast. Default values are @code{40},
13669 @code{160}, @code{80} and @code{255}.
13670 Allowed range is @code{[0, 255]}.
13676 Specify the red, green, blue and alpha fade. Default values are @code{15},
13677 @code{10}, @code{5} and @code{5}.
13678 Allowed range is @code{[0, 255]}.
13681 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
13684 Set the vectorscope drawing mode.
13686 Available values are:
13689 Draw dot for each sample.
13692 Draw line between previous and current sample.
13695 Default value is @samp{dot}.
13698 @subsection Examples
13702 Complete example using @command{ffplay}:
13704 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
13705 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
13711 Concatenate audio and video streams, joining them together one after the
13714 The filter works on segments of synchronized video and audio streams. All
13715 segments must have the same number of streams of each type, and that will
13716 also be the number of streams at output.
13718 The filter accepts the following options:
13723 Set the number of segments. Default is 2.
13726 Set the number of output video streams, that is also the number of video
13727 streams in each segment. Default is 1.
13730 Set the number of output audio streams, that is also the number of audio
13731 streams in each segment. Default is 0.
13734 Activate unsafe mode: do not fail if segments have a different format.
13738 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
13739 @var{a} audio outputs.
13741 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
13742 segment, in the same order as the outputs, then the inputs for the second
13745 Related streams do not always have exactly the same duration, for various
13746 reasons including codec frame size or sloppy authoring. For that reason,
13747 related synchronized streams (e.g. a video and its audio track) should be
13748 concatenated at once. The concat filter will use the duration of the longest
13749 stream in each segment (except the last one), and if necessary pad shorter
13750 audio streams with silence.
13752 For this filter to work correctly, all segments must start at timestamp 0.
13754 All corresponding streams must have the same parameters in all segments; the
13755 filtering system will automatically select a common pixel format for video
13756 streams, and a common sample format, sample rate and channel layout for
13757 audio streams, but other settings, such as resolution, must be converted
13758 explicitly by the user.
13760 Different frame rates are acceptable but will result in variable frame rate
13761 at output; be sure to configure the output file to handle it.
13763 @subsection Examples
13767 Concatenate an opening, an episode and an ending, all in bilingual version
13768 (video in stream 0, audio in streams 1 and 2):
13770 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
13771 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
13772 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
13773 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
13777 Concatenate two parts, handling audio and video separately, using the
13778 (a)movie sources, and adjusting the resolution:
13780 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
13781 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
13782 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
13784 Note that a desync will happen at the stitch if the audio and video streams
13785 do not have exactly the same duration in the first file.
13792 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
13793 it unchanged. By default, it logs a message at a frequency of 10Hz with the
13794 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
13795 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
13797 The filter also has a video output (see the @var{video} option) with a real
13798 time graph to observe the loudness evolution. The graphic contains the logged
13799 message mentioned above, so it is not printed anymore when this option is set,
13800 unless the verbose logging is set. The main graphing area contains the
13801 short-term loudness (3 seconds of analysis), and the gauge on the right is for
13802 the momentary loudness (400 milliseconds).
13804 More information about the Loudness Recommendation EBU R128 on
13805 @url{http://tech.ebu.ch/loudness}.
13807 The filter accepts the following options:
13812 Activate the video output. The audio stream is passed unchanged whether this
13813 option is set or no. The video stream will be the first output stream if
13814 activated. Default is @code{0}.
13817 Set the video size. This option is for video only. For the syntax of this
13819 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13820 Default and minimum resolution is @code{640x480}.
13823 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
13824 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
13825 other integer value between this range is allowed.
13828 Set metadata injection. If set to @code{1}, the audio input will be segmented
13829 into 100ms output frames, each of them containing various loudness information
13830 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
13832 Default is @code{0}.
13835 Force the frame logging level.
13837 Available values are:
13840 information logging level
13842 verbose logging level
13845 By default, the logging level is set to @var{info}. If the @option{video} or
13846 the @option{metadata} options are set, it switches to @var{verbose}.
13851 Available modes can be cumulated (the option is a @code{flag} type). Possible
13855 Disable any peak mode (default).
13857 Enable sample-peak mode.
13859 Simple peak mode looking for the higher sample value. It logs a message
13860 for sample-peak (identified by @code{SPK}).
13862 Enable true-peak mode.
13864 If enabled, the peak lookup is done on an over-sampled version of the input
13865 stream for better peak accuracy. It logs a message for true-peak.
13866 (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}).
13867 This mode requires a build with @code{libswresample}.
13871 Treat mono input files as "dual mono". If a mono file is intended for playback
13872 on a stereo system, its EBU R128 measurement will be perceptually incorrect.
13873 If set to @code{true}, this option will compensate for this effect.
13874 Multi-channel input files are not affected by this option.
13877 Set a specific pan law to be used for the measurement of dual mono files.
13878 This parameter is optional, and has a default value of -3.01dB.
13881 @subsection Examples
13885 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
13887 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
13891 Run an analysis with @command{ffmpeg}:
13893 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
13897 @section interleave, ainterleave
13899 Temporally interleave frames from several inputs.
13901 @code{interleave} works with video inputs, @code{ainterleave} with audio.
13903 These filters read frames from several inputs and send the oldest
13904 queued frame to the output.
13906 Input streams must have a well defined, monotonically increasing frame
13909 In order to submit one frame to output, these filters need to enqueue
13910 at least one frame for each input, so they cannot work in case one
13911 input is not yet terminated and will not receive incoming frames.
13913 For example consider the case when one input is a @code{select} filter
13914 which always drop input frames. The @code{interleave} filter will keep
13915 reading from that input, but it will never be able to send new frames
13916 to output until the input will send an end-of-stream signal.
13918 Also, depending on inputs synchronization, the filters will drop
13919 frames in case one input receives more frames than the other ones, and
13920 the queue is already filled.
13922 These filters accept the following options:
13926 Set the number of different inputs, it is 2 by default.
13929 @subsection Examples
13933 Interleave frames belonging to different streams using @command{ffmpeg}:
13935 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
13939 Add flickering blur effect:
13941 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
13945 @section perms, aperms
13947 Set read/write permissions for the output frames.
13949 These filters are mainly aimed at developers to test direct path in the
13950 following filter in the filtergraph.
13952 The filters accept the following options:
13956 Select the permissions mode.
13958 It accepts the following values:
13961 Do nothing. This is the default.
13963 Set all the output frames read-only.
13965 Set all the output frames directly writable.
13967 Make the frame read-only if writable, and writable if read-only.
13969 Set each output frame read-only or writable randomly.
13973 Set the seed for the @var{random} mode, must be an integer included between
13974 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
13975 @code{-1}, the filter will try to use a good random seed on a best effort
13979 Note: in case of auto-inserted filter between the permission filter and the
13980 following one, the permission might not be received as expected in that
13981 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
13982 perms/aperms filter can avoid this problem.
13984 @section realtime, arealtime
13986 Slow down filtering to match real time approximatively.
13988 These filters will pause the filtering for a variable amount of time to
13989 match the output rate with the input timestamps.
13990 They are similar to the @option{re} option to @code{ffmpeg}.
13992 They accept the following options:
13996 Time limit for the pauses. Any pause longer than that will be considered
13997 a timestamp discontinuity and reset the timer. Default is 2 seconds.
14000 @section select, aselect
14002 Select frames to pass in output.
14004 This filter accepts the following options:
14009 Set expression, which is evaluated for each input frame.
14011 If the expression is evaluated to zero, the frame is discarded.
14013 If the evaluation result is negative or NaN, the frame is sent to the
14014 first output; otherwise it is sent to the output with index
14015 @code{ceil(val)-1}, assuming that the input index starts from 0.
14017 For example a value of @code{1.2} corresponds to the output with index
14018 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
14021 Set the number of outputs. The output to which to send the selected
14022 frame is based on the result of the evaluation. Default value is 1.
14025 The expression can contain the following constants:
14029 The (sequential) number of the filtered frame, starting from 0.
14032 The (sequential) number of the selected frame, starting from 0.
14034 @item prev_selected_n
14035 The sequential number of the last selected frame. It's NAN if undefined.
14038 The timebase of the input timestamps.
14041 The PTS (Presentation TimeStamp) of the filtered video frame,
14042 expressed in @var{TB} units. It's NAN if undefined.
14045 The PTS of the filtered video frame,
14046 expressed in seconds. It's NAN if undefined.
14049 The PTS of the previously filtered video frame. It's NAN if undefined.
14051 @item prev_selected_pts
14052 The PTS of the last previously filtered video frame. It's NAN if undefined.
14054 @item prev_selected_t
14055 The PTS of the last previously selected video frame. It's NAN if undefined.
14058 The PTS of the first video frame in the video. It's NAN if undefined.
14061 The time of the first video frame in the video. It's NAN if undefined.
14063 @item pict_type @emph{(video only)}
14064 The type of the filtered frame. It can assume one of the following
14076 @item interlace_type @emph{(video only)}
14077 The frame interlace type. It can assume one of the following values:
14080 The frame is progressive (not interlaced).
14082 The frame is top-field-first.
14084 The frame is bottom-field-first.
14087 @item consumed_sample_n @emph{(audio only)}
14088 the number of selected samples before the current frame
14090 @item samples_n @emph{(audio only)}
14091 the number of samples in the current frame
14093 @item sample_rate @emph{(audio only)}
14094 the input sample rate
14097 This is 1 if the filtered frame is a key-frame, 0 otherwise.
14100 the position in the file of the filtered frame, -1 if the information
14101 is not available (e.g. for synthetic video)
14103 @item scene @emph{(video only)}
14104 value between 0 and 1 to indicate a new scene; a low value reflects a low
14105 probability for the current frame to introduce a new scene, while a higher
14106 value means the current frame is more likely to be one (see the example below)
14108 @item concatdec_select
14109 The concat demuxer can select only part of a concat input file by setting an
14110 inpoint and an outpoint, but the output packets may not be entirely contained
14111 in the selected interval. By using this variable, it is possible to skip frames
14112 generated by the concat demuxer which are not exactly contained in the selected
14115 This works by comparing the frame pts against the @var{lavf.concat.start_time}
14116 and the @var{lavf.concat.duration} packet metadata values which are also
14117 present in the decoded frames.
14119 The @var{concatdec_select} variable is -1 if the frame pts is at least
14120 start_time and either the duration metadata is missing or the frame pts is less
14121 than start_time + duration, 0 otherwise, and NaN if the start_time metadata is
14124 That basically means that an input frame is selected if its pts is within the
14125 interval set by the concat demuxer.
14129 The default value of the select expression is "1".
14131 @subsection Examples
14135 Select all frames in input:
14140 The example above is the same as:
14152 Select only I-frames:
14154 select='eq(pict_type\,I)'
14158 Select one frame every 100:
14160 select='not(mod(n\,100))'
14164 Select only frames contained in the 10-20 time interval:
14166 select=between(t\,10\,20)
14170 Select only I frames contained in the 10-20 time interval:
14172 select=between(t\,10\,20)*eq(pict_type\,I)
14176 Select frames with a minimum distance of 10 seconds:
14178 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
14182 Use aselect to select only audio frames with samples number > 100:
14184 aselect='gt(samples_n\,100)'
14188 Create a mosaic of the first scenes:
14190 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
14193 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
14197 Send even and odd frames to separate outputs, and compose them:
14199 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
14203 Select useful frames from an ffconcat file which is using inpoints and
14204 outpoints but where the source files are not intra frame only.
14206 ffmpeg -copyts -vsync 0 -segment_time_metadata 1 -i input.ffconcat -vf select=concatdec_select -af aselect=concatdec_select output.avi
14210 @section sendcmd, asendcmd
14212 Send commands to filters in the filtergraph.
14214 These filters read commands to be sent to other filters in the
14217 @code{sendcmd} must be inserted between two video filters,
14218 @code{asendcmd} must be inserted between two audio filters, but apart
14219 from that they act the same way.
14221 The specification of commands can be provided in the filter arguments
14222 with the @var{commands} option, or in a file specified by the
14223 @var{filename} option.
14225 These filters accept the following options:
14228 Set the commands to be read and sent to the other filters.
14230 Set the filename of the commands to be read and sent to the other
14234 @subsection Commands syntax
14236 A commands description consists of a sequence of interval
14237 specifications, comprising a list of commands to be executed when a
14238 particular event related to that interval occurs. The occurring event
14239 is typically the current frame time entering or leaving a given time
14242 An interval is specified by the following syntax:
14244 @var{START}[-@var{END}] @var{COMMANDS};
14247 The time interval is specified by the @var{START} and @var{END} times.
14248 @var{END} is optional and defaults to the maximum time.
14250 The current frame time is considered within the specified interval if
14251 it is included in the interval [@var{START}, @var{END}), that is when
14252 the time is greater or equal to @var{START} and is lesser than
14255 @var{COMMANDS} consists of a sequence of one or more command
14256 specifications, separated by ",", relating to that interval. The
14257 syntax of a command specification is given by:
14259 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
14262 @var{FLAGS} is optional and specifies the type of events relating to
14263 the time interval which enable sending the specified command, and must
14264 be a non-null sequence of identifier flags separated by "+" or "|" and
14265 enclosed between "[" and "]".
14267 The following flags are recognized:
14270 The command is sent when the current frame timestamp enters the
14271 specified interval. In other words, the command is sent when the
14272 previous frame timestamp was not in the given interval, and the
14276 The command is sent when the current frame timestamp leaves the
14277 specified interval. In other words, the command is sent when the
14278 previous frame timestamp was in the given interval, and the
14282 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
14285 @var{TARGET} specifies the target of the command, usually the name of
14286 the filter class or a specific filter instance name.
14288 @var{COMMAND} specifies the name of the command for the target filter.
14290 @var{ARG} is optional and specifies the optional list of argument for
14291 the given @var{COMMAND}.
14293 Between one interval specification and another, whitespaces, or
14294 sequences of characters starting with @code{#} until the end of line,
14295 are ignored and can be used to annotate comments.
14297 A simplified BNF description of the commands specification syntax
14300 @var{COMMAND_FLAG} ::= "enter" | "leave"
14301 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
14302 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
14303 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
14304 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
14305 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
14308 @subsection Examples
14312 Specify audio tempo change at second 4:
14314 asendcmd=c='4.0 atempo tempo 1.5',atempo
14318 Specify a list of drawtext and hue commands in a file.
14320 # show text in the interval 5-10
14321 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
14322 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
14324 # desaturate the image in the interval 15-20
14325 15.0-20.0 [enter] hue s 0,
14326 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
14328 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
14330 # apply an exponential saturation fade-out effect, starting from time 25
14331 25 [enter] hue s exp(25-t)
14334 A filtergraph allowing to read and process the above command list
14335 stored in a file @file{test.cmd}, can be specified with:
14337 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
14342 @section setpts, asetpts
14344 Change the PTS (presentation timestamp) of the input frames.
14346 @code{setpts} works on video frames, @code{asetpts} on audio frames.
14348 This filter accepts the following options:
14353 The expression which is evaluated for each frame to construct its timestamp.
14357 The expression is evaluated through the eval API and can contain the following
14362 frame rate, only defined for constant frame-rate video
14365 The presentation timestamp in input
14368 The count of the input frame for video or the number of consumed samples,
14369 not including the current frame for audio, starting from 0.
14371 @item NB_CONSUMED_SAMPLES
14372 The number of consumed samples, not including the current frame (only
14375 @item NB_SAMPLES, S
14376 The number of samples in the current frame (only audio)
14378 @item SAMPLE_RATE, SR
14379 The audio sample rate.
14382 The PTS of the first frame.
14385 the time in seconds of the first frame
14388 State whether the current frame is interlaced.
14391 the time in seconds of the current frame
14394 original position in the file of the frame, or undefined if undefined
14395 for the current frame
14398 The previous input PTS.
14401 previous input time in seconds
14404 The previous output PTS.
14407 previous output time in seconds
14410 The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
14414 The wallclock (RTC) time at the start of the movie in microseconds.
14417 The timebase of the input timestamps.
14421 @subsection Examples
14425 Start counting PTS from zero
14427 setpts=PTS-STARTPTS
14431 Apply fast motion effect:
14437 Apply slow motion effect:
14443 Set fixed rate of 25 frames per second:
14449 Set fixed rate 25 fps with some jitter:
14451 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
14455 Apply an offset of 10 seconds to the input PTS:
14461 Generate timestamps from a "live source" and rebase onto the current timebase:
14463 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
14467 Generate timestamps by counting samples:
14474 @section settb, asettb
14476 Set the timebase to use for the output frames timestamps.
14477 It is mainly useful for testing timebase configuration.
14479 It accepts the following parameters:
14484 The expression which is evaluated into the output timebase.
14488 The value for @option{tb} is an arithmetic expression representing a
14489 rational. The expression can contain the constants "AVTB" (the default
14490 timebase), "intb" (the input timebase) and "sr" (the sample rate,
14491 audio only). Default value is "intb".
14493 @subsection Examples
14497 Set the timebase to 1/25:
14503 Set the timebase to 1/10:
14509 Set the timebase to 1001/1000:
14515 Set the timebase to 2*intb:
14521 Set the default timebase value:
14528 Convert input audio to a video output representing frequency spectrum
14529 logarithmically using Brown-Puckette constant Q transform algorithm with
14530 direct frequency domain coefficient calculation (but the transform itself
14531 is not really constant Q, instead the Q factor is actually variable/clamped),
14532 with musical tone scale, from E0 to D#10.
14534 The filter accepts the following options:
14538 Specify the video size for the output. It must be even. For the syntax of this option,
14539 check the @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14540 Default value is @code{1920x1080}.
14543 Set the output frame rate. Default value is @code{25}.
14546 Set the bargraph height. It must be even. Default value is @code{-1} which
14547 computes the bargraph height automatically.
14550 Set the axis height. It must be even. Default value is @code{-1} which computes
14551 the axis height automatically.
14554 Set the sonogram height. It must be even. Default value is @code{-1} which
14555 computes the sonogram height automatically.
14558 Set the fullhd resolution. This option is deprecated, use @var{size}, @var{s}
14559 instead. Default value is @code{1}.
14561 @item sono_v, volume
14562 Specify the sonogram volume expression. It can contain variables:
14565 the @var{bar_v} evaluated expression
14566 @item frequency, freq, f
14567 the frequency where it is evaluated
14568 @item timeclamp, tc
14569 the value of @var{timeclamp} option
14573 @item a_weighting(f)
14574 A-weighting of equal loudness
14575 @item b_weighting(f)
14576 B-weighting of equal loudness
14577 @item c_weighting(f)
14578 C-weighting of equal loudness.
14580 Default value is @code{16}.
14582 @item bar_v, volume2
14583 Specify the bargraph volume expression. It can contain variables:
14586 the @var{sono_v} evaluated expression
14587 @item frequency, freq, f
14588 the frequency where it is evaluated
14589 @item timeclamp, tc
14590 the value of @var{timeclamp} option
14594 @item a_weighting(f)
14595 A-weighting of equal loudness
14596 @item b_weighting(f)
14597 B-weighting of equal loudness
14598 @item c_weighting(f)
14599 C-weighting of equal loudness.
14601 Default value is @code{sono_v}.
14603 @item sono_g, gamma
14604 Specify the sonogram gamma. Lower gamma makes the spectrum more contrast,
14605 higher gamma makes the spectrum having more range. Default value is @code{3}.
14606 Acceptable range is @code{[1, 7]}.
14608 @item bar_g, gamma2
14609 Specify the bargraph gamma. Default value is @code{1}. Acceptable range is
14612 @item timeclamp, tc
14613 Specify the transform timeclamp. At low frequency, there is trade-off between
14614 accuracy in time domain and frequency domain. If timeclamp is lower,
14615 event in time domain is represented more accurately (such as fast bass drum),
14616 otherwise event in frequency domain is represented more accurately
14617 (such as bass guitar). Acceptable range is @code{[0.1, 1]}. Default value is @code{0.17}.
14620 Specify the transform base frequency. Default value is @code{20.01523126408007475},
14621 which is frequency 50 cents below E0. Acceptable range is @code{[10, 100000]}.
14624 Specify the transform end frequency. Default value is @code{20495.59681441799654},
14625 which is frequency 50 cents above D#10. Acceptable range is @code{[10, 100000]}.
14628 This option is deprecated and ignored.
14631 Specify the transform length in time domain. Use this option to control accuracy
14632 trade-off between time domain and frequency domain at every frequency sample.
14633 It can contain variables:
14635 @item frequency, freq, f
14636 the frequency where it is evaluated
14637 @item timeclamp, tc
14638 the value of @var{timeclamp} option.
14640 Default value is @code{384*tc/(384+tc*f)}.
14643 Specify the transform count for every video frame. Default value is @code{6}.
14644 Acceptable range is @code{[1, 30]}.
14647 Specify the transform count for every single pixel. Default value is @code{0},
14648 which makes it computed automatically. Acceptable range is @code{[0, 10]}.
14651 Specify font file for use with freetype to draw the axis. If not specified,
14652 use embedded font. Note that drawing with font file or embedded font is not
14653 implemented with custom @var{basefreq} and @var{endfreq}, use @var{axisfile}
14657 Specify font color expression. This is arithmetic expression that should return
14658 integer value 0xRRGGBB. It can contain variables:
14660 @item frequency, freq, f
14661 the frequency where it is evaluated
14662 @item timeclamp, tc
14663 the value of @var{timeclamp} option
14668 midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
14669 @item r(x), g(x), b(x)
14670 red, green, and blue value of intensity x.
14672 Default value is @code{st(0, (midi(f)-59.5)/12);
14673 st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
14674 r(1-ld(1)) + b(ld(1))}.
14677 Specify image file to draw the axis. This option override @var{fontfile} and
14678 @var{fontcolor} option.
14681 Enable/disable drawing text to the axis. If it is set to @code{0}, drawing to
14682 the axis is disabled, ignoring @var{fontfile} and @var{axisfile} option.
14683 Default value is @code{1}.
14687 @subsection Examples
14691 Playing audio while showing the spectrum:
14693 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
14697 Same as above, but with frame rate 30 fps:
14699 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
14703 Playing at 1280x720:
14705 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=s=1280x720:count=4 [out0]'
14709 Disable sonogram display:
14715 A1 and its harmonics: A1, A2, (near)E3, A3:
14717 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),
14718 asplit[a][out1]; [a] showcqt [out0]'
14722 Same as above, but with more accuracy in frequency domain:
14724 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),
14725 asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
14731 bar_v=10:sono_v=bar_v*a_weighting(f)
14735 Custom gamma, now spectrum is linear to the amplitude.
14741 Custom tlength equation:
14743 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)))'
14747 Custom fontcolor and fontfile, C-note is colored green, others are colored blue:
14749 fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))':fontfile=myfont.ttf
14753 Custom frequency range with custom axis using image file:
14755 axisfile=myaxis.png:basefreq=40:endfreq=10000
14761 Convert input audio to video output representing the audio power spectrum.
14762 Audio amplitude is on Y-axis while frequency is on X-axis.
14764 The filter accepts the following options:
14768 Specify size of video. For the syntax of this option, check the
14769 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14770 Default is @code{1024x512}.
14774 This set how each frequency bin will be represented.
14776 It accepts the following values:
14782 Default is @code{bar}.
14785 Set amplitude scale.
14787 It accepts the following values:
14801 Default is @code{log}.
14804 Set frequency scale.
14806 It accepts the following values:
14815 Reverse logarithmic scale.
14817 Default is @code{lin}.
14822 It accepts the following values:
14838 Default is @code{w2048}
14841 Set windowing function.
14843 It accepts the following values:
14861 Default is @code{hanning}.
14864 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
14865 which means optimal overlap for selected window function will be picked.
14868 Set time averaging. Setting this to 0 will display current maximal peaks.
14869 Default is @code{1}, which means time averaging is disabled.
14872 Specify list of colors separated by space or by '|' which will be used to
14873 draw channel frequencies. Unrecognized or missing colors will be replaced
14877 Set channel display mode.
14879 It accepts the following values:
14884 Default is @code{combined}.
14888 @anchor{showspectrum}
14889 @section showspectrum
14891 Convert input audio to a video output, representing the audio frequency
14894 The filter accepts the following options:
14898 Specify the video size for the output. For the syntax of this option, check the
14899 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
14900 Default value is @code{640x512}.
14903 Specify how the spectrum should slide along the window.
14905 It accepts the following values:
14908 the samples start again on the left when they reach the right
14910 the samples scroll from right to left
14912 the samples scroll from left to right
14914 frames are only produced when the samples reach the right
14917 Default value is @code{replace}.
14920 Specify display mode.
14922 It accepts the following values:
14925 all channels are displayed in the same row
14927 all channels are displayed in separate rows
14930 Default value is @samp{combined}.
14933 Specify display color mode.
14935 It accepts the following values:
14938 each channel is displayed in a separate color
14940 each channel is displayed using the same color scheme
14942 each channel is displayed using the rainbow color scheme
14944 each channel is displayed using the moreland color scheme
14946 each channel is displayed using the nebulae color scheme
14948 each channel is displayed using the fire color scheme
14950 each channel is displayed using the fiery color scheme
14952 each channel is displayed using the fruit color scheme
14954 each channel is displayed using the cool color scheme
14957 Default value is @samp{channel}.
14960 Specify scale used for calculating intensity color values.
14962 It accepts the following values:
14967 square root, default
14978 Default value is @samp{sqrt}.
14981 Set saturation modifier for displayed colors. Negative values provide
14982 alternative color scheme. @code{0} is no saturation at all.
14983 Saturation must be in [-10.0, 10.0] range.
14984 Default value is @code{1}.
14987 Set window function.
14989 It accepts the following values:
15009 Default value is @code{hann}.
15012 Set orientation of time vs frequency axis. Can be @code{vertical} or
15013 @code{horizontal}. Default is @code{vertical}.
15016 Set ratio of overlap window. Default value is @code{0}.
15017 When value is @code{1} overlap is set to recommended size for specific
15018 window function currently used.
15021 Set scale gain for calculating intensity color values.
15022 Default value is @code{1}.
15025 Set which data to display. Can be @code{magnitude}, default or @code{phase}.
15028 The usage is very similar to the showwaves filter; see the examples in that
15031 @subsection Examples
15035 Large window with logarithmic color scaling:
15037 showspectrum=s=1280x480:scale=log
15041 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
15043 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
15044 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
15048 @section showspectrumpic
15050 Convert input audio to a single video frame, representing the audio frequency
15053 The filter accepts the following options:
15057 Specify the video size for the output. For the syntax of this option, check the
15058 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15059 Default value is @code{4096x2048}.
15062 Specify display mode.
15064 It accepts the following values:
15067 all channels are displayed in the same row
15069 all channels are displayed in separate rows
15071 Default value is @samp{combined}.
15074 Specify display color mode.
15076 It accepts the following values:
15079 each channel is displayed in a separate color
15081 each channel is displayed using the same color scheme
15083 each channel is displayed using the rainbow color scheme
15085 each channel is displayed using the moreland color scheme
15087 each channel is displayed using the nebulae color scheme
15089 each channel is displayed using the fire color scheme
15091 each channel is displayed using the fiery color scheme
15093 each channel is displayed using the fruit color scheme
15095 each channel is displayed using the cool color scheme
15097 Default value is @samp{intensity}.
15100 Specify scale used for calculating intensity color values.
15102 It accepts the following values:
15107 square root, default
15117 Default value is @samp{log}.
15120 Set saturation modifier for displayed colors. Negative values provide
15121 alternative color scheme. @code{0} is no saturation at all.
15122 Saturation must be in [-10.0, 10.0] range.
15123 Default value is @code{1}.
15126 Set window function.
15128 It accepts the following values:
15147 Default value is @code{hann}.
15150 Set orientation of time vs frequency axis. Can be @code{vertical} or
15151 @code{horizontal}. Default is @code{vertical}.
15154 Set scale gain for calculating intensity color values.
15155 Default value is @code{1}.
15158 Draw time and frequency axes and legends. Default is enabled.
15161 @subsection Examples
15165 Extract an audio spectrogram of a whole audio track
15166 in a 1024x1024 picture using @command{ffmpeg}:
15168 ffmpeg -i audio.flac -lavfi showspectrumpic=s=1024x1024 spectrogram.png
15172 @section showvolume
15174 Convert input audio volume to a video output.
15176 The filter accepts the following options:
15183 Set border width, allowed range is [0, 5]. Default is 1.
15186 Set channel width, allowed range is [80, 1080]. Default is 400.
15189 Set channel height, allowed range is [1, 100]. Default is 20.
15192 Set fade, allowed range is [0.001, 1]. Default is 0.95.
15195 Set volume color expression.
15197 The expression can use the following variables:
15201 Current max volume of channel in dB.
15204 Current channel number, starting from 0.
15208 If set, displays channel names. Default is enabled.
15211 If set, displays volume values. Default is enabled.
15216 Convert input audio to a video output, representing the samples waves.
15218 The filter accepts the following options:
15222 Specify the video size for the output. For the syntax of this option, check the
15223 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15224 Default value is @code{600x240}.
15229 Available values are:
15232 Draw a point for each sample.
15235 Draw a vertical line for each sample.
15238 Draw a point for each sample and a line between them.
15241 Draw a centered vertical line for each sample.
15244 Default value is @code{point}.
15247 Set the number of samples which are printed on the same column. A
15248 larger value will decrease the frame rate. Must be a positive
15249 integer. This option can be set only if the value for @var{rate}
15250 is not explicitly specified.
15253 Set the (approximate) output frame rate. This is done by setting the
15254 option @var{n}. Default value is "25".
15256 @item split_channels
15257 Set if channels should be drawn separately or overlap. Default value is 0.
15260 Set colors separated by '|' which are going to be used for drawing of each channel.
15263 Set amplitude scale. Can be linear @code{lin} or logarithmic @code{log}.
15268 @subsection Examples
15272 Output the input file audio and the corresponding video representation
15275 amovie=a.mp3,asplit[out0],showwaves[out1]
15279 Create a synthetic signal and show it with showwaves, forcing a
15280 frame rate of 30 frames per second:
15282 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
15286 @section showwavespic
15288 Convert input audio to a single video frame, representing the samples waves.
15290 The filter accepts the following options:
15294 Specify the video size for the output. For the syntax of this option, check the
15295 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
15296 Default value is @code{600x240}.
15298 @item split_channels
15299 Set if channels should be drawn separately or overlap. Default value is 0.
15302 Set colors separated by '|' which are going to be used for drawing of each channel.
15305 Set amplitude scale. Can be linear @code{lin} or logarithmic @code{log}.
15309 @subsection Examples
15313 Extract a channel split representation of the wave form of a whole audio track
15314 in a 1024x800 picture using @command{ffmpeg}:
15316 ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
15320 Colorize the waveform with colorchannelmixer. This example will make
15321 the waveform a green color approximately RGB(66,217,150). Additional
15322 channels will be shades of this color.
15324 ffmpeg -i audio.mp3 -filter_complex "showwavespic,colorchannelmixer=rr=66/255:gg=217/255:bb=150/255" waveform.png
15328 @section spectrumsynth
15330 Sythesize audio from 2 input video spectrums, first input stream represents
15331 magnitude across time and second represents phase across time.
15332 The filter will transform from frequency domain as displayed in videos back
15333 to time domain as presented in audio output.
15335 This filter is primarly created for reversing processed @ref{showspectrum}
15336 filter outputs, but can synthesize sound from other spectrograms too.
15337 But in such case results are going to be poor if the phase data is not
15338 available, because in such cases phase data need to be recreated, usually
15339 its just recreated from random noise.
15340 For best results use gray only output (@code{channel} color mode in
15341 @ref{showspectrum} filter) and @code{log} scale for magnitude video and
15342 @code{lin} scale for phase video. To produce phase, for 2nd video, use
15343 @code{data} option. Inputs videos should generally use @code{fullframe}
15344 slide mode as that saves resources needed for decoding video.
15346 The filter accepts the following options:
15350 Specify sample rate of output audio, the sample rate of audio from which
15351 spectrum was generated may differ.
15354 Set number of channels represented in input video spectrums.
15357 Set scale which was used when generating magnitude input spectrum.
15358 Can be @code{lin} or @code{log}. Default is @code{log}.
15361 Set slide which was used when generating inputs spectrums.
15362 Can be @code{replace}, @code{scroll}, @code{fullframe} or @code{rscroll}.
15363 Default is @code{fullframe}.
15366 Set window function used for resynthesis.
15369 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
15370 which means optimal overlap for selected window function will be picked.
15373 Set orientation of input videos. Can be @code{vertical} or @code{horizontal}.
15374 Default is @code{vertical}.
15377 @subsection Examples
15381 First create magnitude and phase videos from audio, assuming audio is stereo with 44100 sample rate,
15382 then resynthesize videos back to audio with spectrumsynth:
15384 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
15385 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
15386 ffmpeg -i magnitude.nut -i phase.nut -lavfi spectrumsynth=channels=2:sample_rate=44100:win_fun=hann:overlap=0.875:slide=fullframe output.flac
15390 @section split, asplit
15392 Split input into several identical outputs.
15394 @code{asplit} works with audio input, @code{split} with video.
15396 The filter accepts a single parameter which specifies the number of outputs. If
15397 unspecified, it defaults to 2.
15399 @subsection Examples
15403 Create two separate outputs from the same input:
15405 [in] split [out0][out1]
15409 To create 3 or more outputs, you need to specify the number of
15412 [in] asplit=3 [out0][out1][out2]
15416 Create two separate outputs from the same input, one cropped and
15419 [in] split [splitout1][splitout2];
15420 [splitout1] crop=100:100:0:0 [cropout];
15421 [splitout2] pad=200:200:100:100 [padout];
15425 Create 5 copies of the input audio with @command{ffmpeg}:
15427 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
15433 Receive commands sent through a libzmq client, and forward them to
15434 filters in the filtergraph.
15436 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
15437 must be inserted between two video filters, @code{azmq} between two
15440 To enable these filters you need to install the libzmq library and
15441 headers and configure FFmpeg with @code{--enable-libzmq}.
15443 For more information about libzmq see:
15444 @url{http://www.zeromq.org/}
15446 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
15447 receives messages sent through a network interface defined by the
15448 @option{bind_address} option.
15450 The received message must be in the form:
15452 @var{TARGET} @var{COMMAND} [@var{ARG}]
15455 @var{TARGET} specifies the target of the command, usually the name of
15456 the filter class or a specific filter instance name.
15458 @var{COMMAND} specifies the name of the command for the target filter.
15460 @var{ARG} is optional and specifies the optional argument list for the
15461 given @var{COMMAND}.
15463 Upon reception, the message is processed and the corresponding command
15464 is injected into the filtergraph. Depending on the result, the filter
15465 will send a reply to the client, adopting the format:
15467 @var{ERROR_CODE} @var{ERROR_REASON}
15471 @var{MESSAGE} is optional.
15473 @subsection Examples
15475 Look at @file{tools/zmqsend} for an example of a zmq client which can
15476 be used to send commands processed by these filters.
15478 Consider the following filtergraph generated by @command{ffplay}
15480 ffplay -dumpgraph 1 -f lavfi "
15481 color=s=100x100:c=red [l];
15482 color=s=100x100:c=blue [r];
15483 nullsrc=s=200x100, zmq [bg];
15484 [bg][l] overlay [bg+l];
15485 [bg+l][r] overlay=x=100 "
15488 To change the color of the left side of the video, the following
15489 command can be used:
15491 echo Parsed_color_0 c yellow | tools/zmqsend
15494 To change the right side:
15496 echo Parsed_color_1 c pink | tools/zmqsend
15499 @c man end MULTIMEDIA FILTERS
15501 @chapter Multimedia Sources
15502 @c man begin MULTIMEDIA SOURCES
15504 Below is a description of the currently available multimedia sources.
15508 This is the same as @ref{movie} source, except it selects an audio
15514 Read audio and/or video stream(s) from a movie container.
15516 It accepts the following parameters:
15520 The name of the resource to read (not necessarily a file; it can also be a
15521 device or a stream accessed through some protocol).
15523 @item format_name, f
15524 Specifies the format assumed for the movie to read, and can be either
15525 the name of a container or an input device. If not specified, the
15526 format is guessed from @var{movie_name} or by probing.
15528 @item seek_point, sp
15529 Specifies the seek point in seconds. The frames will be output
15530 starting from this seek point. The parameter is evaluated with
15531 @code{av_strtod}, so the numerical value may be suffixed by an IS
15532 postfix. The default value is "0".
15535 Specifies the streams to read. Several streams can be specified,
15536 separated by "+". The source will then have as many outputs, in the
15537 same order. The syntax is explained in the ``Stream specifiers''
15538 section in the ffmpeg manual. Two special names, "dv" and "da" specify
15539 respectively the default (best suited) video and audio stream. Default
15540 is "dv", or "da" if the filter is called as "amovie".
15542 @item stream_index, si
15543 Specifies the index of the video stream to read. If the value is -1,
15544 the most suitable video stream will be automatically selected. The default
15545 value is "-1". Deprecated. If the filter is called "amovie", it will select
15546 audio instead of video.
15549 Specifies how many times to read the stream in sequence.
15550 If the value is less than 1, the stream will be read again and again.
15551 Default value is "1".
15553 Note that when the movie is looped the source timestamps are not
15554 changed, so it will generate non monotonically increasing timestamps.
15557 It allows overlaying a second video on top of the main input of
15558 a filtergraph, as shown in this graph:
15560 input -----------> deltapts0 --> overlay --> output
15563 movie --> scale--> deltapts1 -------+
15565 @subsection Examples
15569 Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
15570 on top of the input labelled "in":
15572 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
15573 [in] setpts=PTS-STARTPTS [main];
15574 [main][over] overlay=16:16 [out]
15578 Read from a video4linux2 device, and overlay it on top of the input
15581 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
15582 [in] setpts=PTS-STARTPTS [main];
15583 [main][over] overlay=16:16 [out]
15587 Read the first video stream and the audio stream with id 0x81 from
15588 dvd.vob; the video is connected to the pad named "video" and the audio is
15589 connected to the pad named "audio":
15591 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
15595 @c man end MULTIMEDIA SOURCES