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 Apply cross fade from one input audio stream to another input audio stream.
324 The cross fade is applied for specified duration near the end of first stream.
326 The filter accepts the following options:
330 Specify the number of samples for which the cross fade effect has to last.
331 At the end of the cross fade effect the first input audio will be completely
332 silent. Default is 44100.
335 Specify the duration of the cross fade effect. See
336 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
337 for the accepted syntax.
338 By default the duration is determined by @var{nb_samples}.
339 If set this option is used instead of @var{nb_samples}.
342 Should first stream end overlap with second stream start. Default is enabled.
345 Set curve for cross fade transition for first stream.
348 Set curve for cross fade transition for second stream.
350 For description of available curve types see @ref{afade} filter description.
357 Cross fade from one input to another:
359 ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac
363 Cross fade from one input to another but without overlapping:
365 ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac
371 Delay one or more audio channels.
373 Samples in delayed channel are filled with silence.
375 The filter accepts the following option:
379 Set list of delays in milliseconds for each channel separated by '|'.
380 At least one delay greater than 0 should be provided.
381 Unused delays will be silently ignored. If number of given delays is
382 smaller than number of channels all remaining channels will not be delayed.
389 Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
390 the second channel (and any other channels that may be present) unchanged.
398 Apply echoing to the input audio.
400 Echoes are reflected sound and can occur naturally amongst mountains
401 (and sometimes large buildings) when talking or shouting; digital echo
402 effects emulate this behaviour and are often used to help fill out the
403 sound of a single instrument or vocal. The time difference between the
404 original signal and the reflection is the @code{delay}, and the
405 loudness of the reflected signal is the @code{decay}.
406 Multiple echoes can have different delays and decays.
408 A description of the accepted parameters follows.
412 Set input gain of reflected signal. Default is @code{0.6}.
415 Set output gain of reflected signal. Default is @code{0.3}.
418 Set list of time intervals in milliseconds between original signal and reflections
419 separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}.
420 Default is @code{1000}.
423 Set list of loudnesses of reflected signals separated by '|'.
424 Allowed range for each @code{decay} is @code{(0 - 1.0]}.
425 Default is @code{0.5}.
432 Make it sound as if there are twice as many instruments as are actually playing:
434 aecho=0.8:0.88:60:0.4
438 If delay is very short, then it sound like a (metallic) robot playing music:
444 A longer delay will sound like an open air concert in the mountains:
446 aecho=0.8:0.9:1000:0.3
450 Same as above but with one more mountain:
452 aecho=0.8:0.9:1000|1800:0.3|0.25
458 Modify an audio signal according to the specified expressions.
460 This filter accepts one or more expressions (one for each channel),
461 which are evaluated and used to modify a corresponding audio signal.
463 It accepts the following parameters:
467 Set the '|'-separated expressions list for each separate channel. If
468 the number of input channels is greater than the number of
469 expressions, the last specified expression is used for the remaining
472 @item channel_layout, c
473 Set output channel layout. If not specified, the channel layout is
474 specified by the number of expressions. If set to @samp{same}, it will
475 use by default the same input channel layout.
478 Each expression in @var{exprs} can contain the following constants and functions:
482 channel number of the current expression
485 number of the evaluated sample, starting from 0
491 time of the evaluated sample expressed in seconds
494 @item nb_out_channels
495 input and output number of channels
498 the value of input channel with number @var{CH}
501 Note: this filter is slow. For faster processing you should use a
510 aeval=val(ch)/2:c=same
514 Invert phase of the second channel:
523 Apply fade-in/out effect to input audio.
525 A description of the accepted parameters follows.
529 Specify the effect type, can be either @code{in} for fade-in, or
530 @code{out} for a fade-out effect. Default is @code{in}.
532 @item start_sample, ss
533 Specify the number of the start sample for starting to apply the fade
534 effect. Default is 0.
537 Specify the number of samples for which the fade effect has to last. At
538 the end of the fade-in effect the output audio will have the same
539 volume as the input audio, at the end of the fade-out transition
540 the output audio will be silence. Default is 44100.
543 Specify the start time of the fade effect. Default is 0.
544 The value must be specified as a time duration; see
545 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
546 for the accepted syntax.
547 If set this option is used instead of @var{start_sample}.
550 Specify the duration of the fade effect. See
551 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
552 for the accepted syntax.
553 At the end of the fade-in effect the output audio will have the same
554 volume as the input audio, at the end of the fade-out transition
555 the output audio will be silence.
556 By default the duration is determined by @var{nb_samples}.
557 If set this option is used instead of @var{nb_samples}.
560 Set curve for fade transition.
562 It accepts the following values:
565 select triangular, linear slope (default)
567 select quarter of sine wave
569 select half of sine wave
571 select exponential sine wave
575 select inverted parabola
589 select inverted quarter of sine wave
591 select inverted half of sine wave
593 select double-exponential seat
595 select double-exponential sigmoid
603 Fade in first 15 seconds of audio:
609 Fade out last 25 seconds of a 900 seconds audio:
611 afade=t=out:st=875:d=25
618 Set output format constraints for the input audio. The framework will
619 negotiate the most appropriate format to minimize conversions.
621 It accepts the following parameters:
625 A '|'-separated list of requested sample formats.
628 A '|'-separated list of requested sample rates.
630 @item channel_layouts
631 A '|'-separated list of requested channel layouts.
633 See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils}
634 for the required syntax.
637 If a parameter is omitted, all values are allowed.
639 Force the output to either unsigned 8-bit or signed 16-bit stereo
641 aformat=sample_fmts=u8|s16:channel_layouts=stereo
646 A gate is mainly used to reduce lower parts of a signal. This kind of signal
647 processing reduces disturbing noise between useful signals.
649 Gating is done by detecting the volume below a chosen level @var{threshold}
650 and divide it by the factor set with @var{ratio}. The bottom of the noise
651 floor is set via @var{range}. Because an exact manipulation of the signal
652 would cause distortion of the waveform the reduction can be levelled over
653 time. This is done by setting @var{attack} and @var{release}.
655 @var{attack} determines how long the signal has to fall below the threshold
656 before any reduction will occur and @var{release} sets the time the signal
657 has to raise above the threshold to reduce the reduction again.
658 Shorter signals than the chosen attack time will be left untouched.
662 Set input level before filtering.
665 Set the level of gain reduction when the signal is below the threshold.
668 If a signal rises above this level the gain reduction is released.
671 Set a ratio about which the signal is reduced.
674 Amount of milliseconds the signal has to rise above the threshold before gain
678 Amount of milliseconds the signal has to fall below the threshold before the
679 reduction is increased again.
682 Set amount of amplification of signal after processing.
685 Curve the sharp knee around the threshold to enter gain reduction more softly.
688 Choose if exact signal should be taken for detection or an RMS like one.
691 Choose if the average level between all channels or the louder channel affects
697 The limiter prevents input signal from raising over a desired threshold.
698 This limiter uses lookahead technology to prevent your signal from distorting.
699 It means that there is a small delay after signal is processed. Keep in mind
700 that the delay it produces is the attack time you set.
702 The filter accepts the following options:
706 Don't let signals above this level pass the limiter. The removed amplitude is
707 added automatically. Default is 1.
710 The limiter will reach its attenuation level in this amount of time in
711 milliseconds. Default is 5 milliseconds.
714 Come back from limiting to attenuation 1.0 in this amount of milliseconds.
715 Default is 50 milliseconds.
718 When gain reduction is always needed ASC takes care of releasing to an
719 average reduction level rather than reaching a reduction of 0 in the release
723 Select how much the release time is affected by ASC, 0 means nearly no changes
724 in release time while 1 produces higher release times.
727 Depending on picked setting it is recommended to upsample input 2x or 4x times
728 with @ref{aresample} before applying this filter.
732 Apply a two-pole all-pass filter with central frequency (in Hz)
733 @var{frequency}, and filter-width @var{width}.
734 An all-pass filter changes the audio's frequency to phase relationship
735 without changing its frequency to amplitude relationship.
737 The filter accepts the following options:
744 Set method to specify band-width of filter.
757 Specify the band-width of a filter in width_type units.
763 Merge two or more audio streams into a single multi-channel stream.
765 The filter accepts the following options:
770 Set the number of inputs. Default is 2.
774 If the channel layouts of the inputs are disjoint, and therefore compatible,
775 the channel layout of the output will be set accordingly and the channels
776 will be reordered as necessary. If the channel layouts of the inputs are not
777 disjoint, the output will have all the channels of the first input then all
778 the channels of the second input, in that order, and the channel layout of
779 the output will be the default value corresponding to the total number of
782 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
783 is FC+BL+BR, then the output will be in 5.1, with the channels in the
784 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
785 first input, b1 is the first channel of the second input).
787 On the other hand, if both input are in stereo, the output channels will be
788 in the default order: a1, a2, b1, b2, and the channel layout will be
789 arbitrarily set to 4.0, which may or may not be the expected value.
791 All inputs must have the same sample rate, and format.
793 If inputs do not have the same duration, the output will stop with the
800 Merge two mono files into a stereo stream:
802 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
806 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
808 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
814 Mixes multiple audio inputs into a single output.
816 Note that this filter only supports float samples (the @var{amerge}
817 and @var{pan} audio filters support many formats). If the @var{amix}
818 input has integer samples then @ref{aresample} will be automatically
819 inserted to perform the conversion to float samples.
823 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
825 will mix 3 input audio streams to a single output with the same duration as the
826 first input and a dropout transition time of 3 seconds.
828 It accepts the following parameters:
832 The number of inputs. If unspecified, it defaults to 2.
835 How to determine the end-of-stream.
839 The duration of the longest input. (default)
842 The duration of the shortest input.
845 The duration of the first input.
849 @item dropout_transition
850 The transition time, in seconds, for volume renormalization when an input
851 stream ends. The default value is 2 seconds.
857 Pass the audio source unchanged to the output.
861 Pad the end of an audio stream with silence.
863 This can be used together with @command{ffmpeg} @option{-shortest} to
864 extend audio streams to the same length as the video stream.
866 A description of the accepted options follows.
870 Set silence packet size. Default value is 4096.
873 Set the number of samples of silence to add to the end. After the
874 value is reached, the stream is terminated. This option is mutually
875 exclusive with @option{whole_len}.
878 Set the minimum total number of samples in the output audio stream. If
879 the value is longer than the input audio length, silence is added to
880 the end, until the value is reached. This option is mutually exclusive
881 with @option{pad_len}.
884 If neither the @option{pad_len} nor the @option{whole_len} option is
885 set, the filter will add silence to the end of the input stream
892 Add 1024 samples of silence to the end of the input:
898 Make sure the audio output will contain at least 10000 samples, pad
899 the input with silence if required:
905 Use @command{ffmpeg} to pad the audio input with silence, so that the
906 video stream will always result the shortest and will be converted
907 until the end in the output file when using the @option{shortest}
910 ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT
915 Add a phasing effect to the input audio.
917 A phaser filter creates series of peaks and troughs in the frequency spectrum.
918 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
920 A description of the accepted parameters follows.
924 Set input gain. Default is 0.4.
927 Set output gain. Default is 0.74
930 Set delay in milliseconds. Default is 3.0.
933 Set decay. Default is 0.4.
936 Set modulation speed in Hz. Default is 0.5.
939 Set modulation type. Default is triangular.
941 It accepts the following values:
951 Resample the input audio to the specified parameters, using the
952 libswresample library. If none are specified then the filter will
953 automatically convert between its input and output.
955 This filter is also able to stretch/squeeze the audio data to make it match
956 the timestamps or to inject silence / cut out audio to make it match the
957 timestamps, do a combination of both or do neither.
959 The filter accepts the syntax
960 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
961 expresses a sample rate and @var{resampler_options} is a list of
962 @var{key}=@var{value} pairs, separated by ":". See the
963 ffmpeg-resampler manual for the complete list of supported options.
969 Resample the input audio to 44100Hz:
975 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
976 samples per second compensation:
982 @section asetnsamples
984 Set the number of samples per each output audio frame.
986 The last output packet may contain a different number of samples, as
987 the filter will flush all the remaining samples when the input audio
990 The filter accepts the following options:
994 @item nb_out_samples, n
995 Set the number of frames per each output audio frame. The number is
996 intended as the number of samples @emph{per each channel}.
997 Default value is 1024.
1000 If set to 1, the filter will pad the last audio frame with zeroes, so
1001 that the last frame will contain the same number of samples as the
1002 previous ones. Default value is 1.
1005 For example, to set the number of per-frame samples to 1234 and
1006 disable padding for the last frame, use:
1008 asetnsamples=n=1234:p=0
1013 Set the sample rate without altering the PCM data.
1014 This will result in a change of speed and pitch.
1016 The filter accepts the following options:
1019 @item sample_rate, r
1020 Set the output sample rate. Default is 44100 Hz.
1025 Show a line containing various information for each input audio frame.
1026 The input audio is not modified.
1028 The shown line contains a sequence of key/value pairs of the form
1029 @var{key}:@var{value}.
1031 The following values are shown in the output:
1035 The (sequential) number of the input frame, starting from 0.
1038 The presentation timestamp of the input frame, in time base units; the time base
1039 depends on the filter input pad, and is usually 1/@var{sample_rate}.
1042 The presentation timestamp of the input frame in seconds.
1045 position of the frame in the input stream, -1 if this information in
1046 unavailable and/or meaningless (for example in case of synthetic audio)
1055 The sample rate for the audio frame.
1058 The number of samples (per channel) in the frame.
1061 The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
1062 audio, the data is treated as if all the planes were concatenated.
1064 @item plane_checksums
1065 A list of Adler-32 checksums for each data plane.
1071 Display time domain statistical information about the audio channels.
1072 Statistics are calculated and displayed for each audio channel and,
1073 where applicable, an overall figure is also given.
1075 It accepts the following option:
1078 Short window length in seconds, used for peak and trough RMS measurement.
1079 Default is @code{0.05} (50 milliseconds). Allowed range is @code{[0.1 - 10]}.
1083 Set metadata injection. All the metadata keys are prefixed with @code{lavfi.astats.X},
1084 where @code{X} is channel number starting from 1 or string @code{Overall}. Default is
1087 Available keys for each channel are:
1118 For example full key look like this @code{lavfi.astats.1.DC_offset} or
1119 this @code{lavfi.astats.Overall.Peak_count}.
1121 For description what each key means read bellow.
1124 Set number of frame after which stats are going to be recalculated.
1125 Default is disabled.
1128 A description of each shown parameter follows:
1132 Mean amplitude displacement from zero.
1135 Minimal sample level.
1138 Maximal sample level.
1140 @item Min difference
1141 Minimal difference between two consecutive samples.
1143 @item Max difference
1144 Maximal difference between two consecutive samples.
1146 @item Mean difference
1147 Mean difference between two consecutive samples.
1148 The average of each difference between two consecutive samples.
1152 Standard peak and RMS level measured in dBFS.
1156 Peak and trough values for RMS level measured over a short window.
1159 Standard ratio of peak to RMS level (note: not in dB).
1162 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
1163 (i.e. either @var{Min level} or @var{Max level}).
1166 Number of occasions (not the number of samples) that the signal attained either
1167 @var{Min level} or @var{Max level}.
1170 Overall bit depth of audio. Number of bits used for each sample.
1173 @section astreamsync
1175 Forward two audio streams and control the order the buffers are forwarded.
1177 The filter accepts the following options:
1181 Set the expression deciding which stream should be
1182 forwarded next: if the result is negative, the first stream is forwarded; if
1183 the result is positive or zero, the second stream is forwarded. It can use
1184 the following variables:
1188 number of buffers forwarded so far on each stream
1190 number of samples forwarded so far on each stream
1192 current timestamp of each stream
1195 The default value is @code{t1-t2}, which means to always forward the stream
1196 that has a smaller timestamp.
1199 @subsection Examples
1201 Stress-test @code{amerge} by randomly sending buffers on the wrong
1202 input, while avoiding too much of a desynchronization:
1204 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1205 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1211 Synchronize audio data with timestamps by squeezing/stretching it and/or
1212 dropping samples/adding silence when needed.
1214 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1216 It accepts the following parameters:
1220 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1221 by default. When disabled, time gaps are covered with silence.
1224 The minimum difference between timestamps and audio data (in seconds) to trigger
1225 adding/dropping samples. The default value is 0.1. If you get an imperfect
1226 sync with this filter, try setting this parameter to 0.
1229 The maximum compensation in samples per second. Only relevant with compensate=1.
1230 The default value is 500.
1233 Assume that the first PTS should be this value. The time base is 1 / sample
1234 rate. This allows for padding/trimming at the start of the stream. By default,
1235 no assumption is made about the first frame's expected PTS, so no padding or
1236 trimming is done. For example, this could be set to 0 to pad the beginning with
1237 silence if an audio stream starts after the video stream or to trim any samples
1238 with a negative PTS due to encoder delay.
1246 The filter accepts exactly one parameter, the audio tempo. If not
1247 specified then the filter will assume nominal 1.0 tempo. Tempo must
1248 be in the [0.5, 2.0] range.
1250 @subsection Examples
1254 Slow down audio to 80% tempo:
1260 To speed up audio to 125% tempo:
1268 Trim the input so that the output contains one continuous subpart of the input.
1270 It accepts the following parameters:
1273 Timestamp (in seconds) of the start of the section to keep. I.e. the audio
1274 sample with the timestamp @var{start} will be the first sample in the output.
1277 Specify time of the first audio sample that will be dropped, i.e. the
1278 audio sample immediately preceding the one with the timestamp @var{end} will be
1279 the last sample in the output.
1282 Same as @var{start}, except this option sets the start timestamp in samples
1286 Same as @var{end}, except this option sets the end timestamp in samples instead
1290 The maximum duration of the output in seconds.
1293 The number of the first sample that should be output.
1296 The number of the first sample that should be dropped.
1299 @option{start}, @option{end}, and @option{duration} are expressed as time
1300 duration specifications; see
1301 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
1303 Note that the first two sets of the start/end options and the @option{duration}
1304 option look at the frame timestamp, while the _sample options simply count the
1305 samples that pass through the filter. So start/end_pts and start/end_sample will
1306 give different results when the timestamps are wrong, inexact or do not start at
1307 zero. Also note that this filter does not modify the timestamps. If you wish
1308 to have the output timestamps start at zero, insert the asetpts filter after the
1311 If multiple start or end options are set, this filter tries to be greedy and
1312 keep all samples that match at least one of the specified constraints. To keep
1313 only the part that matches all the constraints at once, chain multiple atrim
1316 The defaults are such that all the input is kept. So it is possible to set e.g.
1317 just the end values to keep everything before the specified time.
1322 Drop everything except the second minute of input:
1324 ffmpeg -i INPUT -af atrim=60:120
1328 Keep only the first 1000 samples:
1330 ffmpeg -i INPUT -af atrim=end_sample=1000
1337 Apply a two-pole Butterworth band-pass filter with central
1338 frequency @var{frequency}, and (3dB-point) band-width width.
1339 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1340 instead of the default: constant 0dB peak gain.
1341 The filter roll off at 6dB per octave (20dB per decade).
1343 The filter accepts the following options:
1347 Set the filter's central frequency. Default is @code{3000}.
1350 Constant skirt gain if set to 1. Defaults to 0.
1353 Set method to specify band-width of filter.
1366 Specify the band-width of a filter in width_type units.
1371 Apply a two-pole Butterworth band-reject filter with central
1372 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1373 The filter roll off at 6dB per octave (20dB per decade).
1375 The filter accepts the following options:
1379 Set the filter's central frequency. Default is @code{3000}.
1382 Set method to specify band-width of filter.
1395 Specify the band-width of a filter in width_type units.
1400 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1401 shelving filter with a response similar to that of a standard
1402 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1404 The filter accepts the following options:
1408 Give the gain at 0 Hz. Its useful range is about -20
1409 (for a large cut) to +20 (for a large boost).
1410 Beware of clipping when using a positive gain.
1413 Set the filter's central frequency and so can be used
1414 to extend or reduce the frequency range to be boosted or cut.
1415 The default value is @code{100} Hz.
1418 Set method to specify band-width of filter.
1431 Determine how steep is the filter's shelf transition.
1436 Apply a biquad IIR filter with the given coefficients.
1437 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1438 are the numerator and denominator coefficients respectively.
1441 Bauer stereo to binaural transformation, which improves headphone listening of
1442 stereo audio records.
1444 It accepts the following parameters:
1448 Pre-defined crossfeed level.
1452 Default level (fcut=700, feed=50).
1455 Chu Moy circuit (fcut=700, feed=60).
1458 Jan Meier circuit (fcut=650, feed=95).
1463 Cut frequency (in Hz).
1472 Remap input channels to new locations.
1474 It accepts the following parameters:
1476 @item channel_layout
1477 The channel layout of the output stream.
1480 Map channels from input to output. The argument is a '|'-separated list of
1481 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1482 @var{in_channel} form. @var{in_channel} can be either the name of the input
1483 channel (e.g. FL for front left) or its index in the input channel layout.
1484 @var{out_channel} is the name of the output channel or its index in the output
1485 channel layout. If @var{out_channel} is not given then it is implicitly an
1486 index, starting with zero and increasing by one for each mapping.
1489 If no mapping is present, the filter will implicitly map input channels to
1490 output channels, preserving indices.
1492 For example, assuming a 5.1+downmix input MOV file,
1494 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1496 will create an output WAV file tagged as stereo from the downmix channels of
1499 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1501 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
1504 @section channelsplit
1506 Split each channel from an input audio stream into a separate output stream.
1508 It accepts the following parameters:
1510 @item channel_layout
1511 The channel layout of the input stream. The default is "stereo".
1514 For example, assuming a stereo input MP3 file,
1516 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1518 will create an output Matroska file with two audio streams, one containing only
1519 the left channel and the other the right channel.
1521 Split a 5.1 WAV file into per-channel files:
1523 ffmpeg -i in.wav -filter_complex
1524 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1525 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1526 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1531 Add a chorus effect to the audio.
1533 Can make a single vocal sound like a chorus, but can also be applied to instrumentation.
1535 Chorus resembles an echo effect with a short delay, but whereas with echo the delay is
1536 constant, with chorus, it is varied using using sinusoidal or triangular modulation.
1537 The modulation depth defines the range the modulated delay is played before or after
1538 the delay. Hence the delayed sound will sound slower or faster, that is the delayed
1539 sound tuned around the original one, like in a chorus where some vocals are slightly
1542 It accepts the following parameters:
1545 Set input gain. Default is 0.4.
1548 Set output gain. Default is 0.4.
1551 Set delays. A typical delay is around 40ms to 60ms.
1563 @subsection Examples
1569 chorus=0.7:0.9:55:0.4:0.25:2
1575 chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3
1579 Fuller sounding chorus with three delays:
1581 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
1586 Compress or expand the audio's dynamic range.
1588 It accepts the following parameters:
1594 A list of times in seconds for each channel over which the instantaneous level
1595 of the input signal is averaged to determine its volume. @var{attacks} refers to
1596 increase of volume and @var{decays} refers to decrease of volume. For most
1597 situations, the attack time (response to the audio getting louder) should be
1598 shorter than the decay time, because the human ear is more sensitive to sudden
1599 loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
1600 a typical value for decay is 0.8 seconds.
1601 If specified number of attacks & decays is lower than number of channels, the last
1602 set attack/decay will be used for all remaining channels.
1605 A list of points for the transfer function, specified in dB relative to the
1606 maximum possible signal amplitude. Each key points list must be defined using
1607 the following syntax: @code{x0/y0|x1/y1|x2/y2|....} or
1608 @code{x0/y0 x1/y1 x2/y2 ....}
1610 The input values must be in strictly increasing order but the transfer function
1611 does not have to be monotonically rising. The point @code{0/0} is assumed but
1612 may be overridden (by @code{0/out-dBn}). Typical values for the transfer
1613 function are @code{-70/-70|-60/-20}.
1616 Set the curve radius in dB for all joints. It defaults to 0.01.
1619 Set the additional gain in dB to be applied at all points on the transfer
1620 function. This allows for easy adjustment of the overall gain.
1624 Set an initial volume, in dB, to be assumed for each channel when filtering
1625 starts. This permits the user to supply a nominal level initially, so that, for
1626 example, a very large gain is not applied to initial signal levels before the
1627 companding has begun to operate. A typical value for audio which is initially
1628 quiet is -90 dB. It defaults to 0.
1631 Set a delay, in seconds. The input audio is analyzed immediately, but audio is
1632 delayed before being fed to the volume adjuster. Specifying a delay
1633 approximately equal to the attack/decay times allows the filter to effectively
1634 operate in predictive rather than reactive mode. It defaults to 0.
1638 @subsection Examples
1642 Make music with both quiet and loud passages suitable for listening to in a
1645 compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
1648 Another example for audio with whisper and explosion parts:
1650 compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0
1654 A noise gate for when the noise is at a lower level than the signal:
1656 compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
1660 Here is another noise gate, this time for when the noise is at a higher level
1661 than the signal (making it, in some ways, similar to squelch):
1663 compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
1668 Apply a DC shift to the audio.
1670 This can be useful to remove a DC offset (caused perhaps by a hardware problem
1671 in the recording chain) from the audio. The effect of a DC offset is reduced
1672 headroom and hence volume. The @ref{astats} filter can be used to determine if
1673 a signal has a DC offset.
1677 Set the DC shift, allowed range is [-1, 1]. It indicates the amount to shift
1681 Optional. It should have a value much less than 1 (e.g. 0.05 or 0.02) and is
1682 used to prevent clipping.
1686 Dynamic Audio Normalizer.
1688 This filter applies a certain amount of gain to the input audio in order
1689 to bring its peak magnitude to a target level (e.g. 0 dBFS). However, in
1690 contrast to more "simple" normalization algorithms, the Dynamic Audio
1691 Normalizer *dynamically* re-adjusts the gain factor to the input audio.
1692 This allows for applying extra gain to the "quiet" sections of the audio
1693 while avoiding distortions or clipping the "loud" sections. In other words:
1694 The Dynamic Audio Normalizer will "even out" the volume of quiet and loud
1695 sections, in the sense that the volume of each section is brought to the
1696 same target level. Note, however, that the Dynamic Audio Normalizer achieves
1697 this goal *without* applying "dynamic range compressing". It will retain 100%
1698 of the dynamic range *within* each section of the audio file.
1702 Set the frame length in milliseconds. In range from 10 to 8000 milliseconds.
1703 Default is 500 milliseconds.
1704 The Dynamic Audio Normalizer processes the input audio in small chunks,
1705 referred to as frames. This is required, because a peak magnitude has no
1706 meaning for just a single sample value. Instead, we need to determine the
1707 peak magnitude for a contiguous sequence of sample values. While a "standard"
1708 normalizer would simply use the peak magnitude of the complete file, the
1709 Dynamic Audio Normalizer determines the peak magnitude individually for each
1710 frame. The length of a frame is specified in milliseconds. By default, the
1711 Dynamic Audio Normalizer uses a frame length of 500 milliseconds, which has
1712 been found to give good results with most files.
1713 Note that the exact frame length, in number of samples, will be determined
1714 automatically, based on the sampling rate of the individual input audio file.
1717 Set the Gaussian filter window size. In range from 3 to 301, must be odd
1718 number. Default is 31.
1719 Probably the most important parameter of the Dynamic Audio Normalizer is the
1720 @code{window size} of the Gaussian smoothing filter. The filter's window size
1721 is specified in frames, centered around the current frame. For the sake of
1722 simplicity, this must be an odd number. Consequently, the default value of 31
1723 takes into account the current frame, as well as the 15 preceding frames and
1724 the 15 subsequent frames. Using a larger window results in a stronger
1725 smoothing effect and thus in less gain variation, i.e. slower gain
1726 adaptation. Conversely, using a smaller window results in a weaker smoothing
1727 effect and thus in more gain variation, i.e. faster gain adaptation.
1728 In other words, the more you increase this value, the more the Dynamic Audio
1729 Normalizer will behave like a "traditional" normalization filter. On the
1730 contrary, the more you decrease this value, the more the Dynamic Audio
1731 Normalizer will behave like a dynamic range compressor.
1734 Set the target peak value. This specifies the highest permissible magnitude
1735 level for the normalized audio input. This filter will try to approach the
1736 target peak magnitude as closely as possible, but at the same time it also
1737 makes sure that the normalized signal will never exceed the peak magnitude.
1738 A frame's maximum local gain factor is imposed directly by the target peak
1739 magnitude. The default value is 0.95 and thus leaves a headroom of 5%*.
1740 It is not recommended to go above this value.
1743 Set the maximum gain factor. In range from 1.0 to 100.0. Default is 10.0.
1744 The Dynamic Audio Normalizer determines the maximum possible (local) gain
1745 factor for each input frame, i.e. the maximum gain factor that does not
1746 result in clipping or distortion. The maximum gain factor is determined by
1747 the frame's highest magnitude sample. However, the Dynamic Audio Normalizer
1748 additionally bounds the frame's maximum gain factor by a predetermined
1749 (global) maximum gain factor. This is done in order to avoid excessive gain
1750 factors in "silent" or almost silent frames. By default, the maximum gain
1751 factor is 10.0, For most inputs the default value should be sufficient and
1752 it usually is not recommended to increase this value. Though, for input
1753 with an extremely low overall volume level, it may be necessary to allow even
1754 higher gain factors. Note, however, that the Dynamic Audio Normalizer does
1755 not simply apply a "hard" threshold (i.e. cut off values above the threshold).
1756 Instead, a "sigmoid" threshold function will be applied. This way, the
1757 gain factors will smoothly approach the threshold value, but never exceed that
1761 Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 - disabled.
1762 By default, the Dynamic Audio Normalizer performs "peak" normalization.
1763 This means that the maximum local gain factor for each frame is defined
1764 (only) by the frame's highest magnitude sample. This way, the samples can
1765 be amplified as much as possible without exceeding the maximum signal
1766 level, i.e. without clipping. Optionally, however, the Dynamic Audio
1767 Normalizer can also take into account the frame's root mean square,
1768 abbreviated RMS. In electrical engineering, the RMS is commonly used to
1769 determine the power of a time-varying signal. It is therefore considered
1770 that the RMS is a better approximation of the "perceived loudness" than
1771 just looking at the signal's peak magnitude. Consequently, by adjusting all
1772 frames to a constant RMS value, a uniform "perceived loudness" can be
1773 established. If a target RMS value has been specified, a frame's local gain
1774 factor is defined as the factor that would result in exactly that RMS value.
1775 Note, however, that the maximum local gain factor is still restricted by the
1776 frame's highest magnitude sample, in order to prevent clipping.
1779 Enable channels coupling. By default is enabled.
1780 By default, the Dynamic Audio Normalizer will amplify all channels by the same
1781 amount. This means the same gain factor will be applied to all channels, i.e.
1782 the maximum possible gain factor is determined by the "loudest" channel.
1783 However, in some recordings, it may happen that the volume of the different
1784 channels is uneven, e.g. one channel may be "quieter" than the other one(s).
1785 In this case, this option can be used to disable the channel coupling. This way,
1786 the gain factor will be determined independently for each channel, depending
1787 only on the individual channel's highest magnitude sample. This allows for
1788 harmonizing the volume of the different channels.
1791 Enable DC bias correction. By default is disabled.
1792 An audio signal (in the time domain) is a sequence of sample values.
1793 In the Dynamic Audio Normalizer these sample values are represented in the
1794 -1.0 to 1.0 range, regardless of the original input format. Normally, the
1795 audio signal, or "waveform", should be centered around the zero point.
1796 That means if we calculate the mean value of all samples in a file, or in a
1797 single frame, then the result should be 0.0 or at least very close to that
1798 value. If, however, there is a significant deviation of the mean value from
1799 0.0, in either positive or negative direction, this is referred to as a
1800 DC bias or DC offset. Since a DC bias is clearly undesirable, the Dynamic
1801 Audio Normalizer provides optional DC bias correction.
1802 With DC bias correction enabled, the Dynamic Audio Normalizer will determine
1803 the mean value, or "DC correction" offset, of each input frame and subtract
1804 that value from all of the frame's sample values which ensures those samples
1805 are centered around 0.0 again. Also, in order to avoid "gaps" at the frame
1806 boundaries, the DC correction offset values will be interpolated smoothly
1807 between neighbouring frames.
1810 Enable alternative boundary mode. By default is disabled.
1811 The Dynamic Audio Normalizer takes into account a certain neighbourhood
1812 around each frame. This includes the preceding frames as well as the
1813 subsequent frames. However, for the "boundary" frames, located at the very
1814 beginning and at the very end of the audio file, not all neighbouring
1815 frames are available. In particular, for the first few frames in the audio
1816 file, the preceding frames are not known. And, similarly, for the last few
1817 frames in the audio file, the subsequent frames are not known. Thus, the
1818 question arises which gain factors should be assumed for the missing frames
1819 in the "boundary" region. The Dynamic Audio Normalizer implements two modes
1820 to deal with this situation. The default boundary mode assumes a gain factor
1821 of exactly 1.0 for the missing frames, resulting in a smooth "fade in" and
1822 "fade out" at the beginning and at the end of the input, respectively.
1825 Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
1826 By default, the Dynamic Audio Normalizer does not apply "traditional"
1827 compression. This means that signal peaks will not be pruned and thus the
1828 full dynamic range will be retained within each local neighbourhood. However,
1829 in some cases it may be desirable to combine the Dynamic Audio Normalizer's
1830 normalization algorithm with a more "traditional" compression.
1831 For this purpose, the Dynamic Audio Normalizer provides an optional compression
1832 (thresholding) function. If (and only if) the compression feature is enabled,
1833 all input frames will be processed by a soft knee thresholding function prior
1834 to the actual normalization process. Put simply, the thresholding function is
1835 going to prune all samples whose magnitude exceeds a certain threshold value.
1836 However, the Dynamic Audio Normalizer does not simply apply a fixed threshold
1837 value. Instead, the threshold value will be adjusted for each individual
1839 In general, smaller parameters result in stronger compression, and vice versa.
1840 Values below 3.0 are not recommended, because audible distortion may appear.
1845 Make audio easier to listen to on headphones.
1847 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1848 so that when listened to on headphones the stereo image is moved from
1849 inside your head (standard for headphones) to outside and in front of
1850 the listener (standard for speakers).
1856 Apply a two-pole peaking equalisation (EQ) filter. With this
1857 filter, the signal-level at and around a selected frequency can
1858 be increased or decreased, whilst (unlike bandpass and bandreject
1859 filters) that at all other frequencies is unchanged.
1861 In order to produce complex equalisation curves, this filter can
1862 be given several times, each with a different central frequency.
1864 The filter accepts the following options:
1868 Set the filter's central frequency in Hz.
1871 Set method to specify band-width of filter.
1884 Specify the band-width of a filter in width_type units.
1887 Set the required gain or attenuation in dB.
1888 Beware of clipping when using a positive gain.
1891 @subsection Examples
1894 Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
1896 equalizer=f=1000:width_type=h:width=200:g=-10
1900 Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
1902 equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
1906 @section extrastereo
1908 Linearly increases the difference between left and right channels which
1909 adds some sort of "live" effect to playback.
1911 The filter accepts the following option:
1915 Sets the difference coefficient (default: 2.5). 0.0 means mono sound
1916 (average of both channels), with 1.0 sound will be unchanged, with
1917 -1.0 left and right channels will be swapped.
1920 Enable clipping. By default is enabled.
1924 Apply a flanging effect to the audio.
1926 The filter accepts the following options:
1930 Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
1933 Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2.
1936 Set percentage regeneration (delayed signal feedback). Range from -95 to 95.
1940 Set percentage of delayed signal mixed with original. Range from 0 to 100.
1941 Default value is 71.
1944 Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
1947 Set swept wave shape, can be @var{triangular} or @var{sinusoidal}.
1948 Default value is @var{sinusoidal}.
1951 Set swept wave percentage-shift for multi channel. Range from 0 to 100.
1952 Default value is 25.
1955 Set delay-line interpolation, @var{linear} or @var{quadratic}.
1956 Default is @var{linear}.
1961 Apply a high-pass filter with 3dB point frequency.
1962 The filter can be either single-pole, or double-pole (the default).
1963 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1965 The filter accepts the following options:
1969 Set frequency in Hz. Default is 3000.
1972 Set number of poles. Default is 2.
1975 Set method to specify band-width of filter.
1988 Specify the band-width of a filter in width_type units.
1989 Applies only to double-pole filter.
1990 The default is 0.707q and gives a Butterworth response.
1995 Join multiple input streams into one multi-channel stream.
1997 It accepts the following parameters:
2001 The number of input streams. It defaults to 2.
2003 @item channel_layout
2004 The desired output channel layout. It defaults to stereo.
2007 Map channels from inputs to output. The argument is a '|'-separated list of
2008 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
2009 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
2010 can be either the name of the input channel (e.g. FL for front left) or its
2011 index in the specified input stream. @var{out_channel} is the name of the output
2015 The filter will attempt to guess the mappings when they are not specified
2016 explicitly. It does so by first trying to find an unused matching input channel
2017 and if that fails it picks the first unused input channel.
2019 Join 3 inputs (with properly set channel layouts):
2021 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
2024 Build a 5.1 output from 6 single-channel streams:
2026 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
2027 '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'
2033 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
2035 To enable compilation of this filter you need to configure FFmpeg with
2036 @code{--enable-ladspa}.
2040 Specifies the name of LADSPA plugin library to load. If the environment
2041 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
2042 each one of the directories specified by the colon separated list in
2043 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
2044 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
2045 @file{/usr/lib/ladspa/}.
2048 Specifies the plugin within the library. Some libraries contain only
2049 one plugin, but others contain many of them. If this is not set filter
2050 will list all available plugins within the specified library.
2053 Set the '|' separated list of controls which are zero or more floating point
2054 values that determine the behavior of the loaded plugin (for example delay,
2056 Controls need to be defined using the following syntax:
2057 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
2058 @var{valuei} is the value set on the @var{i}-th control.
2059 Alternatively they can be also defined using the following syntax:
2060 @var{value0}|@var{value1}|@var{value2}|..., where
2061 @var{valuei} is the value set on the @var{i}-th control.
2062 If @option{controls} is set to @code{help}, all available controls and
2063 their valid ranges are printed.
2065 @item sample_rate, s
2066 Specify the sample rate, default to 44100. Only used if plugin have
2070 Set the number of samples per channel per each output frame, default
2071 is 1024. Only used if plugin have zero inputs.
2074 Set the minimum duration of the sourced audio. See
2075 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2076 for the accepted syntax.
2077 Note that the resulting duration may be greater than the specified duration,
2078 as the generated audio is always cut at the end of a complete frame.
2079 If not specified, or the expressed duration is negative, the audio is
2080 supposed to be generated forever.
2081 Only used if plugin have zero inputs.
2085 @subsection Examples
2089 List all available plugins within amp (LADSPA example plugin) library:
2095 List all available controls and their valid ranges for @code{vcf_notch}
2096 plugin from @code{VCF} library:
2098 ladspa=f=vcf:p=vcf_notch:c=help
2102 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
2105 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
2109 Add reverberation to the audio using TAP-plugins
2110 (Tom's Audio Processing plugins):
2112 ladspa=file=tap_reverb:tap_reverb
2116 Generate white noise, with 0.2 amplitude:
2118 ladspa=file=cmt:noise_source_white:c=c0=.2
2122 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
2123 @code{C* Audio Plugin Suite} (CAPS) library:
2125 ladspa=file=caps:Click:c=c1=20'
2129 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
2131 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
2135 Increase volume by 20dB using fast lookahead limiter from Steve Harris
2136 @code{SWH Plugins} collection:
2138 ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2
2142 Attenuate low frequencies using Multiband EQ from Steve Harris
2143 @code{SWH Plugins} collection:
2145 ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0
2149 @subsection Commands
2151 This filter supports the following commands:
2154 Modify the @var{N}-th control value.
2156 If the specified value is not valid, it is ignored and prior one is kept.
2161 Apply a low-pass filter with 3dB point frequency.
2162 The filter can be either single-pole or double-pole (the default).
2163 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2165 The filter accepts the following options:
2169 Set frequency in Hz. Default is 500.
2172 Set number of poles. Default is 2.
2175 Set method to specify band-width of filter.
2188 Specify the band-width of a filter in width_type units.
2189 Applies only to double-pole filter.
2190 The default is 0.707q and gives a Butterworth response.
2196 Mix channels with specific gain levels. The filter accepts the output
2197 channel layout followed by a set of channels definitions.
2199 This filter is also designed to efficiently remap the channels of an audio
2202 The filter accepts parameters of the form:
2203 "@var{l}|@var{outdef}|@var{outdef}|..."
2207 output channel layout or number of channels
2210 output channel specification, of the form:
2211 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
2214 output channel to define, either a channel name (FL, FR, etc.) or a channel
2215 number (c0, c1, etc.)
2218 multiplicative coefficient for the channel, 1 leaving the volume unchanged
2221 input channel to use, see out_name for details; it is not possible to mix
2222 named and numbered input channels
2225 If the `=' in a channel specification is replaced by `<', then the gains for
2226 that specification will be renormalized so that the total is 1, thus
2227 avoiding clipping noise.
2229 @subsection Mixing examples
2231 For example, if you want to down-mix from stereo to mono, but with a bigger
2232 factor for the left channel:
2234 pan=1c|c0=0.9*c0+0.1*c1
2237 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
2238 7-channels surround:
2240 pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
2243 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
2244 that should be preferred (see "-ac" option) unless you have very specific
2247 @subsection Remapping examples
2249 The channel remapping will be effective if, and only if:
2252 @item gain coefficients are zeroes or ones,
2253 @item only one input per channel output,
2256 If all these conditions are satisfied, the filter will notify the user ("Pure
2257 channel mapping detected"), and use an optimized and lossless method to do the
2260 For example, if you have a 5.1 source and want a stereo audio stream by
2261 dropping the extra channels:
2263 pan="stereo| c0=FL | c1=FR"
2266 Given the same source, you can also switch front left and front right channels
2267 and keep the input channel layout:
2269 pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
2272 If the input is a stereo audio stream, you can mute the front left channel (and
2273 still keep the stereo channel layout) with:
2278 Still with a stereo audio stream input, you can copy the right channel in both
2279 front left and right:
2281 pan="stereo| c0=FR | c1=FR"
2286 ReplayGain scanner filter. This filter takes an audio stream as an input and
2287 outputs it unchanged.
2288 At end of filtering it displays @code{track_gain} and @code{track_peak}.
2292 Convert the audio sample format, sample rate and channel layout. It is
2293 not meant to be used directly.
2296 Apply time-stretching and pitch-shifting with librubberband.
2298 The filter accepts the following options:
2302 Set tempo scale factor.
2305 Set pitch scale factor.
2308 Set transients detector.
2309 Possible values are:
2318 Possible values are:
2327 Possible values are:
2334 Set processing window size.
2335 Possible values are:
2344 Possible values are:
2351 Enable formant preservation when shift pitching.
2352 Possible values are:
2360 Possible values are:
2369 Possible values are:
2376 @section sidechaincompress
2378 This filter acts like normal compressor but has the ability to compress
2379 detected signal using second input signal.
2380 It needs two input streams and returns one output stream.
2381 First input stream will be processed depending on second stream signal.
2382 The filtered signal then can be filtered with other filters in later stages of
2383 processing. See @ref{pan} and @ref{amerge} filter.
2385 The filter accepts the following options:
2389 If a signal of second stream raises above this level it will affect the gain
2390 reduction of first stream.
2391 By default is 0.125. Range is between 0.00097563 and 1.
2394 Set a ratio about which the signal is reduced. 1:2 means that if the level
2395 raised 4dB above the threshold, it will be only 2dB above after the reduction.
2396 Default is 2. Range is between 1 and 20.
2399 Amount of milliseconds the signal has to rise above the threshold before gain
2400 reduction starts. Default is 20. Range is between 0.01 and 2000.
2403 Amount of milliseconds the signal has to fall bellow the threshold before
2404 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
2407 Set the amount by how much signal will be amplified after processing.
2408 Default is 2. Range is from 1 and 64.
2411 Curve the sharp knee around the threshold to enter gain reduction more softly.
2412 Default is 2.82843. Range is between 1 and 8.
2415 Choose if the @code{average} level between all channels of side-chain stream
2416 or the louder(@code{maximum}) channel of side-chain stream affects the
2417 reduction. Default is @code{average}.
2420 Should the exact signal be taken in case of @code{peak} or an RMS one in case
2421 of @code{rms}. Default is @code{rms} which is mainly smoother.
2424 @subsection Examples
2428 Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
2429 depending on the signal of 2nd input and later compressed signal to be
2430 merged with 2nd input:
2432 ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
2436 @section silencedetect
2438 Detect silence in an audio stream.
2440 This filter logs a message when it detects that the input audio volume is less
2441 or equal to a noise tolerance value for a duration greater or equal to the
2442 minimum detected noise duration.
2444 The printed times and duration are expressed in seconds.
2446 The filter accepts the following options:
2450 Set silence duration until notification (default is 2 seconds).
2453 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
2454 specified value) or amplitude ratio. Default is -60dB, or 0.001.
2457 @subsection Examples
2461 Detect 5 seconds of silence with -50dB noise tolerance:
2463 silencedetect=n=-50dB:d=5
2467 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
2468 tolerance in @file{silence.mp3}:
2470 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
2474 @section silenceremove
2476 Remove silence from the beginning, middle or end of the audio.
2478 The filter accepts the following options:
2482 This value is used to indicate if audio should be trimmed at beginning of
2483 the audio. A value of zero indicates no silence should be trimmed from the
2484 beginning. When specifying a non-zero value, it trims audio up until it
2485 finds non-silence. Normally, when trimming silence from beginning of audio
2486 the @var{start_periods} will be @code{1} but it can be increased to higher
2487 values to trim all audio up to specific count of non-silence periods.
2488 Default value is @code{0}.
2490 @item start_duration
2491 Specify the amount of time that non-silence must be detected before it stops
2492 trimming audio. By increasing the duration, bursts of noises can be treated
2493 as silence and trimmed off. Default value is @code{0}.
2495 @item start_threshold
2496 This indicates what sample value should be treated as silence. For digital
2497 audio, a value of @code{0} may be fine but for audio recorded from analog,
2498 you may wish to increase the value to account for background noise.
2499 Can be specified in dB (in case "dB" is appended to the specified value)
2500 or amplitude ratio. Default value is @code{0}.
2503 Set the count for trimming silence from the end of audio.
2504 To remove silence from the middle of a file, specify a @var{stop_periods}
2505 that is negative. This value is then treated as a positive value and is
2506 used to indicate the effect should restart processing as specified by
2507 @var{start_periods}, making it suitable for removing periods of silence
2508 in the middle of the audio.
2509 Default value is @code{0}.
2512 Specify a duration of silence that must exist before audio is not copied any
2513 more. By specifying a higher duration, silence that is wanted can be left in
2515 Default value is @code{0}.
2517 @item stop_threshold
2518 This is the same as @option{start_threshold} but for trimming silence from
2520 Can be specified in dB (in case "dB" is appended to the specified value)
2521 or amplitude ratio. Default value is @code{0}.
2524 This indicate that @var{stop_duration} length of audio should be left intact
2525 at the beginning of each period of silence.
2526 For example, if you want to remove long pauses between words but do not want
2527 to remove the pauses completely. Default value is @code{0}.
2531 @subsection Examples
2535 The following example shows how this filter can be used to start a recording
2536 that does not contain the delay at the start which usually occurs between
2537 pressing the record button and the start of the performance:
2539 silenceremove=1:5:0.02
2543 @section stereotools
2545 This filter has some handy utilities to manage stereo signals, for converting
2546 M/S stereo recordings to L/R signal while having control over the parameters
2547 or spreading the stereo image of master track.
2549 The filter accepts the following options:
2553 Set input level before filtering for both channels. Defaults is 1.
2554 Allowed range is from 0.015625 to 64.
2557 Set output level after filtering for both channels. Defaults is 1.
2558 Allowed range is from 0.015625 to 64.
2561 Set input balance between both channels. Default is 0.
2562 Allowed range is from -1 to 1.
2565 Set output balance between both channels. Default is 0.
2566 Allowed range is from -1 to 1.
2569 Enable softclipping. Results in analog distortion instead of harsh digital 0dB
2570 clipping. Disabled by default.
2573 Mute the left channel. Disabled by default.
2576 Mute the right channel. Disabled by default.
2579 Change the phase of the left channel. Disabled by default.
2582 Change the phase of the right channel. Disabled by default.
2585 Set stereo mode. Available values are:
2589 Left/Right to Left/Right, this is default.
2592 Left/Right to Mid/Side.
2595 Mid/Side to Left/Right.
2598 Left/Right to Left/Left.
2601 Left/Right to Right/Right.
2604 Left/Right to Left + Right.
2607 Left/Right to Right/Left.
2611 Set level of side signal. Default is 1.
2612 Allowed range is from 0.015625 to 64.
2615 Set balance of side signal. Default is 0.
2616 Allowed range is from -1 to 1.
2619 Set level of the middle signal. Default is 1.
2620 Allowed range is from 0.015625 to 64.
2623 Set middle signal pan. Default is 0. Allowed range is from -1 to 1.
2626 Set stereo base between mono and inversed channels. Default is 0.
2627 Allowed range is from -1 to 1.
2630 Set delay in milliseconds how much to delay left from right channel and
2631 vice versa. Default is 0. Allowed range is from -20 to 20.
2634 Set S/C level. Default is 1. Allowed range is from 1 to 100.
2637 Set the stereo phase in degrees. Default is 0. Allowed range is from 0 to 360.
2640 @section stereowiden
2642 This filter enhance the stereo effect by suppressing signal common to both
2643 channels and by delaying the signal of left into right and vice versa,
2644 thereby widening the stereo effect.
2646 The filter accepts the following options:
2650 Time in milliseconds of the delay of left signal into right and vice versa.
2651 Default is 20 milliseconds.
2654 Amount of gain in delayed signal into right and vice versa. Gives a delay
2655 effect of left signal in right output and vice versa which gives widening
2656 effect. Default is 0.3.
2659 Cross feed of left into right with inverted phase. This helps in suppressing
2660 the mono. If the value is 1 it will cancel all the signal common to both
2661 channels. Default is 0.3.
2664 Set level of input signal of original channel. Default is 0.8.
2669 Boost or cut treble (upper) frequencies of the audio using a two-pole
2670 shelving filter with a response similar to that of a standard
2671 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
2673 The filter accepts the following options:
2677 Give the gain at whichever is the lower of ~22 kHz and the
2678 Nyquist frequency. Its useful range is about -20 (for a large cut)
2679 to +20 (for a large boost). Beware of clipping when using a positive gain.
2682 Set the filter's central frequency and so can be used
2683 to extend or reduce the frequency range to be boosted or cut.
2684 The default value is @code{3000} Hz.
2687 Set method to specify band-width of filter.
2700 Determine how steep is the filter's shelf transition.
2705 Sinusoidal amplitude modulation.
2707 The filter accepts the following options:
2711 Modulation frequency in Hertz. Modulation frequencies in the subharmonic range
2712 (20 Hz or lower) will result in a tremolo effect.
2713 This filter may also be used as a ring modulator by specifying
2714 a modulation frequency higher than 20 Hz.
2715 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
2718 Depth of modulation as a percentage. Range is 0.0 - 1.0.
2719 Default value is 0.5.
2724 Adjust the input audio volume.
2726 It accepts the following parameters:
2730 Set audio volume expression.
2732 Output values are clipped to the maximum value.
2734 The output audio volume is given by the relation:
2736 @var{output_volume} = @var{volume} * @var{input_volume}
2739 The default value for @var{volume} is "1.0".
2742 This parameter represents the mathematical precision.
2744 It determines which input sample formats will be allowed, which affects the
2745 precision of the volume scaling.
2749 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
2751 32-bit floating-point; this limits input sample format to FLT. (default)
2753 64-bit floating-point; this limits input sample format to DBL.
2757 Choose the behaviour on encountering ReplayGain side data in input frames.
2761 Remove ReplayGain side data, ignoring its contents (the default).
2764 Ignore ReplayGain side data, but leave it in the frame.
2767 Prefer the track gain, if present.
2770 Prefer the album gain, if present.
2773 @item replaygain_preamp
2774 Pre-amplification gain in dB to apply to the selected replaygain gain.
2776 Default value for @var{replaygain_preamp} is 0.0.
2779 Set when the volume expression is evaluated.
2781 It accepts the following values:
2784 only evaluate expression once during the filter initialization, or
2785 when the @samp{volume} command is sent
2788 evaluate expression for each incoming frame
2791 Default value is @samp{once}.
2794 The volume expression can contain the following parameters.
2798 frame number (starting at zero)
2801 @item nb_consumed_samples
2802 number of samples consumed by the filter
2804 number of samples in the current frame
2806 original frame position in the file
2812 PTS at start of stream
2814 time at start of stream
2820 last set volume value
2823 Note that when @option{eval} is set to @samp{once} only the
2824 @var{sample_rate} and @var{tb} variables are available, all other
2825 variables will evaluate to NAN.
2827 @subsection Commands
2829 This filter supports the following commands:
2832 Modify the volume expression.
2833 The command accepts the same syntax of the corresponding option.
2835 If the specified expression is not valid, it is kept at its current
2837 @item replaygain_noclip
2838 Prevent clipping by limiting the gain applied.
2840 Default value for @var{replaygain_noclip} is 1.
2844 @subsection Examples
2848 Halve the input audio volume:
2852 volume=volume=-6.0206dB
2855 In all the above example the named key for @option{volume} can be
2856 omitted, for example like in:
2862 Increase input audio power by 6 decibels using fixed-point precision:
2864 volume=volume=6dB:precision=fixed
2868 Fade volume after time 10 with an annihilation period of 5 seconds:
2870 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
2874 @section volumedetect
2876 Detect the volume of the input video.
2878 The filter has no parameters. The input is not modified. Statistics about
2879 the volume will be printed in the log when the input stream end is reached.
2881 In particular it will show the mean volume (root mean square), maximum
2882 volume (on a per-sample basis), and the beginning of a histogram of the
2883 registered volume values (from the maximum value to a cumulated 1/1000 of
2886 All volumes are in decibels relative to the maximum PCM value.
2888 @subsection Examples
2890 Here is an excerpt of the output:
2892 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
2893 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
2894 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
2895 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
2896 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
2897 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
2898 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
2899 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
2900 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
2906 The mean square energy is approximately -27 dB, or 10^-2.7.
2908 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
2910 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
2913 In other words, raising the volume by +4 dB does not cause any clipping,
2914 raising it by +5 dB causes clipping for 6 samples, etc.
2916 @c man end AUDIO FILTERS
2918 @chapter Audio Sources
2919 @c man begin AUDIO SOURCES
2921 Below is a description of the currently available audio sources.
2925 Buffer audio frames, and make them available to the filter chain.
2927 This source is mainly intended for a programmatic use, in particular
2928 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
2930 It accepts the following parameters:
2934 The timebase which will be used for timestamps of submitted frames. It must be
2935 either a floating-point number or in @var{numerator}/@var{denominator} form.
2938 The sample rate of the incoming audio buffers.
2941 The sample format of the incoming audio buffers.
2942 Either a sample format name or its corresponding integer representation from
2943 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
2945 @item channel_layout
2946 The channel layout of the incoming audio buffers.
2947 Either a channel layout name from channel_layout_map in
2948 @file{libavutil/channel_layout.c} or its corresponding integer representation
2949 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
2952 The number of channels of the incoming audio buffers.
2953 If both @var{channels} and @var{channel_layout} are specified, then they
2958 @subsection Examples
2961 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
2964 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
2965 Since the sample format with name "s16p" corresponds to the number
2966 6 and the "stereo" channel layout corresponds to the value 0x3, this is
2969 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
2974 Generate an audio signal specified by an expression.
2976 This source accepts in input one or more expressions (one for each
2977 channel), which are evaluated and used to generate a corresponding
2980 This source accepts the following options:
2984 Set the '|'-separated expressions list for each separate channel. In case the
2985 @option{channel_layout} option is not specified, the selected channel layout
2986 depends on the number of provided expressions. Otherwise the last
2987 specified expression is applied to the remaining output channels.
2989 @item channel_layout, c
2990 Set the channel layout. The number of channels in the specified layout
2991 must be equal to the number of specified expressions.
2994 Set the minimum duration of the sourced audio. See
2995 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2996 for the accepted syntax.
2997 Note that the resulting duration may be greater than the specified
2998 duration, as the generated audio is always cut at the end of a
3001 If not specified, or the expressed duration is negative, the audio is
3002 supposed to be generated forever.
3005 Set the number of samples per channel per each output frame,
3008 @item sample_rate, s
3009 Specify the sample rate, default to 44100.
3012 Each expression in @var{exprs} can contain the following constants:
3016 number of the evaluated sample, starting from 0
3019 time of the evaluated sample expressed in seconds, starting from 0
3026 @subsection Examples
3036 Generate a sin signal with frequency of 440 Hz, set sample rate to
3039 aevalsrc="sin(440*2*PI*t):s=8000"
3043 Generate a two channels signal, specify the channel layout (Front
3044 Center + Back Center) explicitly:
3046 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
3050 Generate white noise:
3052 aevalsrc="-2+random(0)"
3056 Generate an amplitude modulated signal:
3058 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
3062 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
3064 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
3071 The null audio source, return unprocessed audio frames. It is mainly useful
3072 as a template and to be employed in analysis / debugging tools, or as
3073 the source for filters which ignore the input data (for example the sox
3076 This source accepts the following options:
3080 @item channel_layout, cl
3082 Specifies the channel layout, and can be either an integer or a string
3083 representing a channel layout. The default value of @var{channel_layout}
3086 Check the channel_layout_map definition in
3087 @file{libavutil/channel_layout.c} for the mapping between strings and
3088 channel layout values.
3090 @item sample_rate, r
3091 Specifies the sample rate, and defaults to 44100.
3094 Set the number of samples per requested frames.
3098 @subsection Examples
3102 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
3104 anullsrc=r=48000:cl=4
3108 Do the same operation with a more obvious syntax:
3110 anullsrc=r=48000:cl=mono
3114 All the parameters need to be explicitly defined.
3118 Synthesize a voice utterance using the libflite library.
3120 To enable compilation of this filter you need to configure FFmpeg with
3121 @code{--enable-libflite}.
3123 Note that the flite library is not thread-safe.
3125 The filter accepts the following options:
3130 If set to 1, list the names of the available voices and exit
3131 immediately. Default value is 0.
3134 Set the maximum number of samples per frame. Default value is 512.
3137 Set the filename containing the text to speak.
3140 Set the text to speak.
3143 Set the voice to use for the speech synthesis. Default value is
3144 @code{kal}. See also the @var{list_voices} option.
3147 @subsection Examples
3151 Read from file @file{speech.txt}, and synthesize the text using the
3152 standard flite voice:
3154 flite=textfile=speech.txt
3158 Read the specified text selecting the @code{slt} voice:
3160 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3164 Input text to ffmpeg:
3166 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3170 Make @file{ffplay} speak the specified text, using @code{flite} and
3171 the @code{lavfi} device:
3173 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
3177 For more information about libflite, check:
3178 @url{http://www.speech.cs.cmu.edu/flite/}
3182 Generate an audio signal made of a sine wave with amplitude 1/8.
3184 The audio signal is bit-exact.
3186 The filter accepts the following options:
3191 Set the carrier frequency. Default is 440 Hz.
3193 @item beep_factor, b
3194 Enable a periodic beep every second with frequency @var{beep_factor} times
3195 the carrier frequency. Default is 0, meaning the beep is disabled.
3197 @item sample_rate, r
3198 Specify the sample rate, default is 44100.
3201 Specify the duration of the generated audio stream.
3203 @item samples_per_frame
3204 Set the number of samples per output frame.
3206 The expression can contain the following constants:
3210 The (sequential) number of the output audio frame, starting from 0.
3213 The PTS (Presentation TimeStamp) of the output audio frame,
3214 expressed in @var{TB} units.
3217 The PTS of the output audio frame, expressed in seconds.
3220 The timebase of the output audio frames.
3223 Default is @code{1024}.
3226 @subsection Examples
3231 Generate a simple 440 Hz sine wave:
3237 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
3241 sine=frequency=220:beep_factor=4:duration=5
3245 Generate a 1 kHz sine wave following @code{1602,1601,1602,1601,1602} NTSC
3248 sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
3252 @c man end AUDIO SOURCES
3254 @chapter Audio Sinks
3255 @c man begin AUDIO SINKS
3257 Below is a description of the currently available audio sinks.
3259 @section abuffersink
3261 Buffer audio frames, and make them available to the end of filter chain.
3263 This sink is mainly intended for programmatic use, in particular
3264 through the interface defined in @file{libavfilter/buffersink.h}
3265 or the options system.
3267 It accepts a pointer to an AVABufferSinkContext structure, which
3268 defines the incoming buffers' formats, to be passed as the opaque
3269 parameter to @code{avfilter_init_filter} for initialization.
3272 Null audio sink; do absolutely nothing with the input audio. It is
3273 mainly useful as a template and for use in analysis / debugging
3276 @c man end AUDIO SINKS
3278 @chapter Video Filters
3279 @c man begin VIDEO FILTERS
3281 When you configure your FFmpeg build, you can disable any of the
3282 existing filters using @code{--disable-filters}.
3283 The configure output will show the video filters included in your
3286 Below is a description of the currently available video filters.
3288 @section alphaextract
3290 Extract the alpha component from the input as a grayscale video. This
3291 is especially useful with the @var{alphamerge} filter.
3295 Add or replace the alpha component of the primary input with the
3296 grayscale value of a second input. This is intended for use with
3297 @var{alphaextract} to allow the transmission or storage of frame
3298 sequences that have alpha in a format that doesn't support an alpha
3301 For example, to reconstruct full frames from a normal YUV-encoded video
3302 and a separate video created with @var{alphaextract}, you might use:
3304 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
3307 Since this filter is designed for reconstruction, it operates on frame
3308 sequences without considering timestamps, and terminates when either
3309 input reaches end of stream. This will cause problems if your encoding
3310 pipeline drops frames. If you're trying to apply an image as an
3311 overlay to a video stream, consider the @var{overlay} filter instead.
3315 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
3316 and libavformat to work. On the other hand, it is limited to ASS (Advanced
3317 Substation Alpha) subtitles files.
3319 This filter accepts the following option in addition to the common options from
3320 the @ref{subtitles} filter:
3324 Set the shaping engine
3326 Available values are:
3329 The default libass shaping engine, which is the best available.
3331 Fast, font-agnostic shaper that can do only substitutions
3333 Slower shaper using OpenType for substitutions and positioning
3336 The default is @code{auto}.
3340 Apply an Adaptive Temporal Averaging Denoiser to the video input.
3342 The filter accepts the following options:
3346 Set threshold A for 1st plane. Default is 0.02.
3347 Valid range is 0 to 0.3.
3350 Set threshold B for 1st plane. Default is 0.04.
3351 Valid range is 0 to 5.
3354 Set threshold A for 2nd plane. Default is 0.02.
3355 Valid range is 0 to 0.3.
3358 Set threshold B for 2nd plane. Default is 0.04.
3359 Valid range is 0 to 5.
3362 Set threshold A for 3rd plane. Default is 0.02.
3363 Valid range is 0 to 0.3.
3366 Set threshold B for 3rd plane. Default is 0.04.
3367 Valid range is 0 to 5.
3369 Threshold A is designed to react on abrupt changes in the input signal and
3370 threshold B is designed to react on continuous changes in the input signal.
3373 Set number of frames filter will use for averaging. Default is 33. Must be odd
3374 number in range [5, 129].
3379 Compute the bounding box for the non-black pixels in the input frame
3382 This filter computes the bounding box containing all the pixels with a
3383 luminance value greater than the minimum allowed value.
3384 The parameters describing the bounding box are printed on the filter
3387 The filter accepts the following option:
3391 Set the minimal luminance value. Default is @code{16}.
3394 @section blackdetect
3396 Detect video intervals that are (almost) completely black. Can be
3397 useful to detect chapter transitions, commercials, or invalid
3398 recordings. Output lines contains the time for the start, end and
3399 duration of the detected black interval expressed in seconds.
3401 In order to display the output lines, you need to set the loglevel at
3402 least to the AV_LOG_INFO value.
3404 The filter accepts the following options:
3407 @item black_min_duration, d
3408 Set the minimum detected black duration expressed in seconds. It must
3409 be a non-negative floating point number.
3411 Default value is 2.0.
3413 @item picture_black_ratio_th, pic_th
3414 Set the threshold for considering a picture "black".
3415 Express the minimum value for the ratio:
3417 @var{nb_black_pixels} / @var{nb_pixels}
3420 for which a picture is considered black.
3421 Default value is 0.98.
3423 @item pixel_black_th, pix_th
3424 Set the threshold for considering a pixel "black".
3426 The threshold expresses the maximum pixel luminance value for which a
3427 pixel is considered "black". The provided value is scaled according to
3428 the following equation:
3430 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
3433 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
3434 the input video format, the range is [0-255] for YUV full-range
3435 formats and [16-235] for YUV non full-range formats.
3437 Default value is 0.10.
3440 The following example sets the maximum pixel threshold to the minimum
3441 value, and detects only black intervals of 2 or more seconds:
3443 blackdetect=d=2:pix_th=0.00
3448 Detect frames that are (almost) completely black. Can be useful to
3449 detect chapter transitions or commercials. Output lines consist of
3450 the frame number of the detected frame, the percentage of blackness,
3451 the position in the file if known or -1 and the timestamp in seconds.
3453 In order to display the output lines, you need to set the loglevel at
3454 least to the AV_LOG_INFO value.
3456 It accepts the following parameters:
3461 The percentage of the pixels that have to be below the threshold; it defaults to
3464 @item threshold, thresh
3465 The threshold below which a pixel value is considered black; it defaults to
3470 @section blend, tblend
3472 Blend two video frames into each other.
3474 The @code{blend} filter takes two input streams and outputs one
3475 stream, the first input is the "top" layer and second input is
3476 "bottom" layer. Output terminates when shortest input terminates.
3478 The @code{tblend} (time blend) filter takes two consecutive frames
3479 from one single stream, and outputs the result obtained by blending
3480 the new frame on top of the old frame.
3482 A description of the accepted options follows.
3490 Set blend mode for specific pixel component or all pixel components in case
3491 of @var{all_mode}. Default value is @code{normal}.
3493 Available values for component modes are:
3531 Set blend opacity for specific pixel component or all pixel components in case
3532 of @var{all_opacity}. Only used in combination with pixel component blend modes.
3539 Set blend expression for specific pixel component or all pixel components in case
3540 of @var{all_expr}. Note that related mode options will be ignored if those are set.
3542 The expressions can use the following variables:
3546 The sequential number of the filtered frame, starting from @code{0}.
3550 the coordinates of the current sample
3554 the width and height of currently filtered plane
3558 Width and height scale depending on the currently filtered plane. It is the
3559 ratio between the corresponding luma plane number of pixels and the current
3560 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3561 @code{0.5,0.5} for chroma planes.
3564 Time of the current frame, expressed in seconds.
3567 Value of pixel component at current location for first video frame (top layer).
3570 Value of pixel component at current location for second video frame (bottom layer).
3574 Force termination when the shortest input terminates. Default is
3575 @code{0}. This option is only defined for the @code{blend} filter.
3578 Continue applying the last bottom frame after the end of the stream. A value of
3579 @code{0} disable the filter after the last frame of the bottom layer is reached.
3580 Default is @code{1}. This option is only defined for the @code{blend} filter.
3583 @subsection Examples
3587 Apply transition from bottom layer to top layer in first 10 seconds:
3589 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
3593 Apply 1x1 checkerboard effect:
3595 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
3599 Apply uncover left effect:
3601 blend=all_expr='if(gte(N*SW+X,W),A,B)'
3605 Apply uncover down effect:
3607 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
3611 Apply uncover up-left effect:
3613 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
3617 Display differences between the current and the previous frame:
3619 tblend=all_mode=difference128
3625 Apply a boxblur algorithm to the input video.
3627 It accepts the following parameters:
3631 @item luma_radius, lr
3632 @item luma_power, lp
3633 @item chroma_radius, cr
3634 @item chroma_power, cp
3635 @item alpha_radius, ar
3636 @item alpha_power, ap
3640 A description of the accepted options follows.
3643 @item luma_radius, lr
3644 @item chroma_radius, cr
3645 @item alpha_radius, ar
3646 Set an expression for the box radius in pixels used for blurring the
3647 corresponding input plane.
3649 The radius value must be a non-negative number, and must not be
3650 greater than the value of the expression @code{min(w,h)/2} for the
3651 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
3654 Default value for @option{luma_radius} is "2". If not specified,
3655 @option{chroma_radius} and @option{alpha_radius} default to the
3656 corresponding value set for @option{luma_radius}.
3658 The expressions can contain the following constants:
3662 The input width and height in pixels.
3666 The input chroma image width and height in pixels.
3670 The horizontal and vertical chroma subsample values. For example, for the
3671 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
3674 @item luma_power, lp
3675 @item chroma_power, cp
3676 @item alpha_power, ap
3677 Specify how many times the boxblur filter is applied to the
3678 corresponding plane.
3680 Default value for @option{luma_power} is 2. If not specified,
3681 @option{chroma_power} and @option{alpha_power} default to the
3682 corresponding value set for @option{luma_power}.
3684 A value of 0 will disable the effect.
3687 @subsection Examples
3691 Apply a boxblur filter with the luma, chroma, and alpha radii
3694 boxblur=luma_radius=2:luma_power=1
3699 Set the luma radius to 2, and alpha and chroma radius to 0:
3701 boxblur=2:1:cr=0:ar=0
3705 Set the luma and chroma radii to a fraction of the video dimension:
3707 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
3712 YUV colorspace color/chroma keying.
3714 The filter accepts the following options:
3718 The color which will be replaced with transparency.
3721 Similarity percentage with the key color.
3723 0.01 matches only the exact key color, while 1.0 matches everything.
3728 0.0 makes pixels either fully transparent, or not transparent at all.
3730 Higher values result in semi-transparent pixels, with a higher transparency
3731 the more similar the pixels color is to the key color.
3734 Signals that the color passed is already in YUV instead of RGB.
3736 Litteral colors like "green" or "red" don't make sense with this enabled anymore.
3737 This can be used to pass exact YUV values as hexadecimal numbers.
3740 @subsection Examples
3744 Make every green pixel in the input image transparent:
3746 ffmpeg -i input.png -vf chromakey=green out.png
3750 Overlay a greenscreen-video on top of a static black background.
3752 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
3758 Visualize information exported by some codecs.
3760 Some codecs can export information through frames using side-data or other
3761 means. For example, some MPEG based codecs export motion vectors through the
3762 @var{export_mvs} flag in the codec @option{flags2} option.
3764 The filter accepts the following option:
3768 Set motion vectors to visualize.
3770 Available flags for @var{mv} are:
3774 forward predicted MVs of P-frames
3776 forward predicted MVs of B-frames
3778 backward predicted MVs of B-frames
3782 @subsection Examples
3786 Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}:
3788 ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
3792 @section colorbalance
3793 Modify intensity of primary colors (red, green and blue) of input frames.
3795 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
3796 regions for the red-cyan, green-magenta or blue-yellow balance.
3798 A positive adjustment value shifts the balance towards the primary color, a negative
3799 value towards the complementary color.
3801 The filter accepts the following options:
3807 Adjust red, green and blue shadows (darkest pixels).
3812 Adjust red, green and blue midtones (medium pixels).
3817 Adjust red, green and blue highlights (brightest pixels).
3819 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3822 @subsection Examples
3826 Add red color cast to shadows:
3833 RGB colorspace color keying.
3835 The filter accepts the following options:
3839 The color which will be replaced with transparency.
3842 Similarity percentage with the key color.
3844 0.01 matches only the exact key color, while 1.0 matches everything.
3849 0.0 makes pixels either fully transparent, or not transparent at all.
3851 Higher values result in semi-transparent pixels, with a higher transparency
3852 the more similar the pixels color is to the key color.
3855 @subsection Examples
3859 Make every green pixel in the input image transparent:
3861 ffmpeg -i input.png -vf colorkey=green out.png
3865 Overlay a greenscreen-video on top of a static background image.
3867 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
3871 @section colorlevels
3873 Adjust video input frames using levels.
3875 The filter accepts the following options:
3882 Adjust red, green, blue and alpha input black point.
3883 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3889 Adjust red, green, blue and alpha input white point.
3890 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{1}.
3892 Input levels are used to lighten highlights (bright tones), darken shadows
3893 (dark tones), change the balance of bright and dark tones.
3899 Adjust red, green, blue and alpha output black point.
3900 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{0}.
3906 Adjust red, green, blue and alpha output white point.
3907 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{1}.
3909 Output levels allows manual selection of a constrained output level range.
3912 @subsection Examples
3916 Make video output darker:
3918 colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
3924 colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
3928 Make video output lighter:
3930 colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
3934 Increase brightness:
3936 colorlevels=romin=0.5:gomin=0.5:bomin=0.5
3940 @section colorchannelmixer
3942 Adjust video input frames by re-mixing color channels.
3944 This filter modifies a color channel by adding the values associated to
3945 the other channels of the same pixels. For example if the value to
3946 modify is red, the output value will be:
3948 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
3951 The filter accepts the following options:
3958 Adjust contribution of input red, green, blue and alpha channels for output red channel.
3959 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
3965 Adjust contribution of input red, green, blue and alpha channels for output green channel.
3966 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
3972 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
3973 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
3979 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
3980 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
3982 Allowed ranges for options are @code{[-2.0, 2.0]}.
3985 @subsection Examples
3989 Convert source to grayscale:
3991 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
3994 Simulate sepia tones:
3996 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
4000 @section colormatrix
4002 Convert color matrix.
4004 The filter accepts the following options:
4009 Specify the source and destination color matrix. Both values must be
4012 The accepted values are:
4028 For example to convert from BT.601 to SMPTE-240M, use the command:
4030 colormatrix=bt601:smpte240m
4035 Copy the input source unchanged to the output. This is mainly useful for
4040 Crop the input video to given dimensions.
4042 It accepts the following parameters:
4046 The width of the output video. It defaults to @code{iw}.
4047 This expression is evaluated only once during the filter
4048 configuration, or when the @samp{w} or @samp{out_w} command is sent.
4051 The height of the output video. It defaults to @code{ih}.
4052 This expression is evaluated only once during the filter
4053 configuration, or when the @samp{h} or @samp{out_h} command is sent.
4056 The horizontal position, in the input video, of the left edge of the output
4057 video. It defaults to @code{(in_w-out_w)/2}.
4058 This expression is evaluated per-frame.
4061 The vertical position, in the input video, of the top edge of the output video.
4062 It defaults to @code{(in_h-out_h)/2}.
4063 This expression is evaluated per-frame.
4066 If set to 1 will force the output display aspect ratio
4067 to be the same of the input, by changing the output sample aspect
4068 ratio. It defaults to 0.
4071 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
4072 expressions containing the following constants:
4077 The computed values for @var{x} and @var{y}. They are evaluated for
4082 The input width and height.
4086 These are the same as @var{in_w} and @var{in_h}.
4090 The output (cropped) width and height.
4094 These are the same as @var{out_w} and @var{out_h}.
4097 same as @var{iw} / @var{ih}
4100 input sample aspect ratio
4103 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4107 horizontal and vertical chroma subsample values. For example for the
4108 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4111 The number of the input frame, starting from 0.
4114 the position in the file of the input frame, NAN if unknown
4117 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
4121 The expression for @var{out_w} may depend on the value of @var{out_h},
4122 and the expression for @var{out_h} may depend on @var{out_w}, but they
4123 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
4124 evaluated after @var{out_w} and @var{out_h}.
4126 The @var{x} and @var{y} parameters specify the expressions for the
4127 position of the top-left corner of the output (non-cropped) area. They
4128 are evaluated for each frame. If the evaluated value is not valid, it
4129 is approximated to the nearest valid value.
4131 The expression for @var{x} may depend on @var{y}, and the expression
4132 for @var{y} may depend on @var{x}.
4134 @subsection Examples
4138 Crop area with size 100x100 at position (12,34).
4143 Using named options, the example above becomes:
4145 crop=w=100:h=100:x=12:y=34
4149 Crop the central input area with size 100x100:
4155 Crop the central input area with size 2/3 of the input video:
4157 crop=2/3*in_w:2/3*in_h
4161 Crop the input video central square:
4168 Delimit the rectangle with the top-left corner placed at position
4169 100:100 and the right-bottom corner corresponding to the right-bottom
4170 corner of the input image.
4172 crop=in_w-100:in_h-100:100:100
4176 Crop 10 pixels from the left and right borders, and 20 pixels from
4177 the top and bottom borders
4179 crop=in_w-2*10:in_h-2*20
4183 Keep only the bottom right quarter of the input image:
4185 crop=in_w/2:in_h/2:in_w/2:in_h/2
4189 Crop height for getting Greek harmony:
4191 crop=in_w:1/PHI*in_w
4195 Apply trembling effect:
4197 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)
4201 Apply erratic camera effect depending on timestamp:
4203 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)"
4207 Set x depending on the value of y:
4209 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
4213 @subsection Commands
4215 This filter supports the following commands:
4221 Set width/height of the output video and the horizontal/vertical position
4223 The command accepts the same syntax of the corresponding option.
4225 If the specified expression is not valid, it is kept at its current
4231 Auto-detect the crop size.
4233 It calculates the necessary cropping parameters and prints the
4234 recommended parameters via the logging system. The detected dimensions
4235 correspond to the non-black area of the input video.
4237 It accepts the following parameters:
4242 Set higher black value threshold, which can be optionally specified
4243 from nothing (0) to everything (255 for 8bit based formats). An intensity
4244 value greater to the set value is considered non-black. It defaults to 24.
4245 You can also specify a value between 0.0 and 1.0 which will be scaled depending
4246 on the bitdepth of the pixel format.
4249 The value which the width/height should be divisible by. It defaults to
4250 16. The offset is automatically adjusted to center the video. Use 2 to
4251 get only even dimensions (needed for 4:2:2 video). 16 is best when
4252 encoding to most video codecs.
4254 @item reset_count, reset
4255 Set the counter that determines after how many frames cropdetect will
4256 reset the previously detected largest video area and start over to
4257 detect the current optimal crop area. Default value is 0.
4259 This can be useful when channel logos distort the video area. 0
4260 indicates 'never reset', and returns the largest area encountered during
4267 Apply color adjustments using curves.
4269 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
4270 component (red, green and blue) has its values defined by @var{N} key points
4271 tied from each other using a smooth curve. The x-axis represents the pixel
4272 values from the input frame, and the y-axis the new pixel values to be set for
4275 By default, a component curve is defined by the two points @var{(0;0)} and
4276 @var{(1;1)}. This creates a straight line where each original pixel value is
4277 "adjusted" to its own value, which means no change to the image.
4279 The filter allows you to redefine these two points and add some more. A new
4280 curve (using a natural cubic spline interpolation) will be define to pass
4281 smoothly through all these new coordinates. The new defined points needs to be
4282 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
4283 be in the @var{[0;1]} interval. If the computed curves happened to go outside
4284 the vector spaces, the values will be clipped accordingly.
4286 If there is no key point defined in @code{x=0}, the filter will automatically
4287 insert a @var{(0;0)} point. In the same way, if there is no key point defined
4288 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
4290 The filter accepts the following options:
4294 Select one of the available color presets. This option can be used in addition
4295 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
4296 options takes priority on the preset values.
4297 Available presets are:
4300 @item color_negative
4303 @item increase_contrast
4305 @item linear_contrast
4306 @item medium_contrast
4308 @item strong_contrast
4311 Default is @code{none}.
4313 Set the master key points. These points will define a second pass mapping. It
4314 is sometimes called a "luminance" or "value" mapping. It can be used with
4315 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
4316 post-processing LUT.
4318 Set the key points for the red component.
4320 Set the key points for the green component.
4322 Set the key points for the blue component.
4324 Set the key points for all components (not including master).
4325 Can be used in addition to the other key points component
4326 options. In this case, the unset component(s) will fallback on this
4327 @option{all} setting.
4329 Specify a Photoshop curves file (@code{.acv}) to import the settings from.
4332 To avoid some filtergraph syntax conflicts, each key points list need to be
4333 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
4335 @subsection Examples
4339 Increase slightly the middle level of blue:
4341 curves=blue='0.5/0.58'
4347 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
4349 Here we obtain the following coordinates for each components:
4352 @code{(0;0.11) (0.42;0.51) (1;0.95)}
4354 @code{(0;0) (0.50;0.48) (1;1)}
4356 @code{(0;0.22) (0.49;0.44) (1;0.80)}
4360 The previous example can also be achieved with the associated built-in preset:
4362 curves=preset=vintage
4372 Use a Photoshop preset and redefine the points of the green component:
4374 curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'
4380 Denoise frames using 2D DCT (frequency domain filtering).
4382 This filter is not designed for real time.
4384 The filter accepts the following options:
4388 Set the noise sigma constant.
4390 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
4391 coefficient (absolute value) below this threshold with be dropped.
4393 If you need a more advanced filtering, see @option{expr}.
4395 Default is @code{0}.
4398 Set number overlapping pixels for each block. Since the filter can be slow, you
4399 may want to reduce this value, at the cost of a less effective filter and the
4400 risk of various artefacts.
4402 If the overlapping value doesn't permit processing the whole input width or
4403 height, a warning will be displayed and according borders won't be denoised.
4405 Default value is @var{blocksize}-1, which is the best possible setting.
4408 Set the coefficient factor expression.
4410 For each coefficient of a DCT block, this expression will be evaluated as a
4411 multiplier value for the coefficient.
4413 If this is option is set, the @option{sigma} option will be ignored.
4415 The absolute value of the coefficient can be accessed through the @var{c}
4419 Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the
4420 @var{blocksize}, which is the width and height of the processed blocks.
4422 The default value is @var{3} (8x8) and can be raised to @var{4} for a
4423 @var{blocksize} of 16x16. Note that changing this setting has huge consequences
4424 on the speed processing. Also, a larger block size does not necessarily means a
4428 @subsection Examples
4430 Apply a denoise with a @option{sigma} of @code{4.5}:
4435 The same operation can be achieved using the expression system:
4437 dctdnoiz=e='gte(c, 4.5*3)'
4440 Violent denoise using a block size of @code{16x16}:
4447 Remove banding artifacts from input video.
4448 It works by replacing banded pixels with average value of referenced pixels.
4450 The filter accepts the following options:
4457 Set banding detection threshold for each plane. Default is 0.02.
4458 Valid range is 0.00003 to 0.5.
4459 If difference between current pixel and reference pixel is less than threshold,
4460 it will be considered as banded.
4463 Banding detection range in pixels. Default is 16. If positive, random number
4464 in range 0 to set value will be used. If negative, exact absolute value
4466 The range defines square of four pixels around current pixel.
4469 Set direction in radians from which four pixel will be compared. If positive,
4470 random direction from 0 to set direction will be picked. If negative, exact of
4471 absolute value will be picked. For example direction 0, -PI or -2*PI radians
4472 will pick only pixels on same row and -PI/2 will pick only pixels on same
4476 If enabled, current pixel is compared with average value of all four
4477 surrounding pixels. The default is enabled. If disabled current pixel is
4478 compared with all four surrounding pixels. The pixel is considered banded
4479 if only all four differences with surrounding pixels are less than threshold.
4485 Drop duplicated frames at regular intervals.
4487 The filter accepts the following options:
4491 Set the number of frames from which one will be dropped. Setting this to
4492 @var{N} means one frame in every batch of @var{N} frames will be dropped.
4493 Default is @code{5}.
4496 Set the threshold for duplicate detection. If the difference metric for a frame
4497 is less than or equal to this value, then it is declared as duplicate. Default
4501 Set scene change threshold. Default is @code{15}.
4505 Set the size of the x and y-axis blocks used during metric calculations.
4506 Larger blocks give better noise suppression, but also give worse detection of
4507 small movements. Must be a power of two. Default is @code{32}.
4510 Mark main input as a pre-processed input and activate clean source input
4511 stream. This allows the input to be pre-processed with various filters to help
4512 the metrics calculation while keeping the frame selection lossless. When set to
4513 @code{1}, the first stream is for the pre-processed input, and the second
4514 stream is the clean source from where the kept frames are chosen. Default is
4518 Set whether or not chroma is considered in the metric calculations. Default is
4524 Apply deflate effect to the video.
4526 This filter replaces the pixel by the local(3x3) average by taking into account
4527 only values lower than the pixel.
4529 It accepts the following options:
4536 Allows to limit the maximum change for each plane, default is 65535.
4537 If 0, plane will remain unchanged.
4542 Remove judder produced by partially interlaced telecined content.
4544 Judder can be introduced, for instance, by @ref{pullup} filter. If the original
4545 source was partially telecined content then the output of @code{pullup,dejudder}
4546 will have a variable frame rate. May change the recorded frame rate of the
4547 container. Aside from that change, this filter will not affect constant frame
4550 The option available in this filter is:
4554 Specify the length of the window over which the judder repeats.
4556 Accepts any integer greater than 1. Useful values are:
4560 If the original was telecined from 24 to 30 fps (Film to NTSC).
4563 If the original was telecined from 25 to 30 fps (PAL to NTSC).
4566 If a mixture of the two.
4569 The default is @samp{4}.
4574 Suppress a TV station logo by a simple interpolation of the surrounding
4575 pixels. Just set a rectangle covering the logo and watch it disappear
4576 (and sometimes something even uglier appear - your mileage may vary).
4578 It accepts the following parameters:
4583 Specify the top left corner coordinates of the logo. They must be
4588 Specify the width and height of the logo to clear. They must be
4592 Specify the thickness of the fuzzy edge of the rectangle (added to
4593 @var{w} and @var{h}). The default value is 4.
4596 When set to 1, a green rectangle is drawn on the screen to simplify
4597 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
4598 The default value is 0.
4600 The rectangle is drawn on the outermost pixels which will be (partly)
4601 replaced with interpolated values. The values of the next pixels
4602 immediately outside this rectangle in each direction will be used to
4603 compute the interpolated pixel values inside the rectangle.
4607 @subsection Examples
4611 Set a rectangle covering the area with top left corner coordinates 0,0
4612 and size 100x77, and a band of size 10:
4614 delogo=x=0:y=0:w=100:h=77:band=10
4621 Attempt to fix small changes in horizontal and/or vertical shift. This
4622 filter helps remove camera shake from hand-holding a camera, bumping a
4623 tripod, moving on a vehicle, etc.
4625 The filter accepts the following options:
4633 Specify a rectangular area where to limit the search for motion
4635 If desired the search for motion vectors can be limited to a
4636 rectangular area of the frame defined by its top left corner, width
4637 and height. These parameters have the same meaning as the drawbox
4638 filter which can be used to visualise the position of the bounding
4641 This is useful when simultaneous movement of subjects within the frame
4642 might be confused for camera motion by the motion vector search.
4644 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
4645 then the full frame is used. This allows later options to be set
4646 without specifying the bounding box for the motion vector search.
4648 Default - search the whole frame.
4652 Specify the maximum extent of movement in x and y directions in the
4653 range 0-64 pixels. Default 16.
4656 Specify how to generate pixels to fill blanks at the edge of the
4657 frame. Available values are:
4660 Fill zeroes at blank locations
4662 Original image at blank locations
4664 Extruded edge value at blank locations
4666 Mirrored edge at blank locations
4668 Default value is @samp{mirror}.
4671 Specify the blocksize to use for motion search. Range 4-128 pixels,
4675 Specify the contrast threshold for blocks. Only blocks with more than
4676 the specified contrast (difference between darkest and lightest
4677 pixels) will be considered. Range 1-255, default 125.
4680 Specify the search strategy. Available values are:
4683 Set exhaustive search
4685 Set less exhaustive search.
4687 Default value is @samp{exhaustive}.
4690 If set then a detailed log of the motion search is written to the
4694 If set to 1, specify using OpenCL capabilities, only available if
4695 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
4701 Apply an exact inverse of the telecine operation. It requires a predefined
4702 pattern specified using the pattern option which must be the same as that passed
4703 to the telecine filter.
4705 This filter accepts the following options:
4714 The default value is @code{top}.
4718 A string of numbers representing the pulldown pattern you wish to apply.
4719 The default value is @code{23}.
4722 A number representing position of the first frame with respect to the telecine
4723 pattern. This is to be used if the stream is cut. The default value is @code{0}.
4728 Apply dilation effect to the video.
4730 This filter replaces the pixel by the local(3x3) maximum.
4732 It accepts the following options:
4739 Allows to limit the maximum change for each plane, default is 65535.
4740 If 0, plane will remain unchanged.
4743 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
4746 Flags to local 3x3 coordinates maps like this:
4755 Draw a colored box on the input image.
4757 It accepts the following parameters:
4762 The expressions which specify the top left corner coordinates of the box. It defaults to 0.
4766 The expressions which specify the width and height of the box; if 0 they are interpreted as
4767 the input width and height. It defaults to 0.
4770 Specify the color of the box to write. For the general syntax of this option,
4771 check the "Color" section in the ffmpeg-utils manual. If the special
4772 value @code{invert} is used, the box edge color is the same as the
4773 video with inverted luma.
4776 The expression which sets the thickness of the box edge. Default value is @code{3}.
4778 See below for the list of accepted constants.
4781 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4782 following constants:
4786 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4790 horizontal and vertical chroma subsample values. For example for the
4791 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4795 The input width and height.
4798 The input sample aspect ratio.
4802 The x and y offset coordinates where the box is drawn.
4806 The width and height of the drawn box.
4809 The thickness of the drawn box.
4811 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
4812 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
4816 @subsection Examples
4820 Draw a black box around the edge of the input image:
4826 Draw a box with color red and an opacity of 50%:
4828 drawbox=10:20:200:60:red@@0.5
4831 The previous example can be specified as:
4833 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
4837 Fill the box with pink color:
4839 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
4843 Draw a 2-pixel red 2.40:1 mask:
4845 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
4849 @section drawgraph, adrawgraph
4851 Draw a graph using input video or audio metadata.
4853 It accepts the following parameters:
4857 Set 1st frame metadata key from which metadata values will be used to draw a graph.
4860 Set 1st foreground color expression.
4863 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
4866 Set 2nd foreground color expression.
4869 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
4872 Set 3rd foreground color expression.
4875 Set 4th frame metadata key from which metadata values will be used to draw a graph.
4878 Set 4th foreground color expression.
4881 Set minimal value of metadata value.
4884 Set maximal value of metadata value.
4887 Set graph background color. Default is white.
4892 Available values for mode is:
4899 Default is @code{line}.
4904 Available values for slide is:
4907 Draw new frame when right border is reached.
4910 Replace old columns with new ones.
4913 Scroll from right to left.
4916 Scroll from left to right.
4919 Default is @code{frame}.
4922 Set size of graph video. For the syntax of this option, check the
4923 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
4924 The default value is @code{900x256}.
4926 The foreground color expressions can use the following variables:
4929 Minimal value of metadata value.
4932 Maximal value of metadata value.
4935 Current metadata key value.
4938 The color is defined as 0xAABBGGRR.
4941 Example using metadata from @ref{signalstats} filter:
4943 signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
4946 Example using metadata from @ref{ebur128} filter:
4948 ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
4953 Draw a grid on the input image.
4955 It accepts the following parameters:
4960 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
4964 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
4965 input width and height, respectively, minus @code{thickness}, so image gets
4966 framed. Default to 0.
4969 Specify the color of the grid. For the general syntax of this option,
4970 check the "Color" section in the ffmpeg-utils manual. If the special
4971 value @code{invert} is used, the grid color is the same as the
4972 video with inverted luma.
4975 The expression which sets the thickness of the grid line. Default value is @code{1}.
4977 See below for the list of accepted constants.
4980 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4981 following constants:
4985 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4989 horizontal and vertical chroma subsample values. For example for the
4990 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4994 The input grid cell width and height.
4997 The input sample aspect ratio.
5001 The x and y coordinates of some point of grid intersection (meant to configure offset).
5005 The width and height of the drawn cell.
5008 The thickness of the drawn cell.
5010 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
5011 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
5015 @subsection Examples
5019 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
5021 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
5025 Draw a white 3x3 grid with an opacity of 50%:
5027 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
5034 Draw a text string or text from a specified file on top of a video, using the
5035 libfreetype library.
5037 To enable compilation of this filter, you need to configure FFmpeg with
5038 @code{--enable-libfreetype}.
5039 To enable default font fallback and the @var{font} option you need to
5040 configure FFmpeg with @code{--enable-libfontconfig}.
5041 To enable the @var{text_shaping} option, you need to configure FFmpeg with
5042 @code{--enable-libfribidi}.
5046 It accepts the following parameters:
5051 Used to draw a box around text using the background color.
5052 The value must be either 1 (enable) or 0 (disable).
5053 The default value of @var{box} is 0.
5056 Set the width of the border to be drawn around the box using @var{boxcolor}.
5057 The default value of @var{boxborderw} is 0.
5060 The color to be used for drawing box around text. For the syntax of this
5061 option, check the "Color" section in the ffmpeg-utils manual.
5063 The default value of @var{boxcolor} is "white".
5066 Set the width of the border to be drawn around the text using @var{bordercolor}.
5067 The default value of @var{borderw} is 0.
5070 Set the color to be used for drawing border around text. For the syntax of this
5071 option, check the "Color" section in the ffmpeg-utils manual.
5073 The default value of @var{bordercolor} is "black".
5076 Select how the @var{text} is expanded. Can be either @code{none},
5077 @code{strftime} (deprecated) or
5078 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
5082 If true, check and fix text coords to avoid clipping.
5085 The color to be used for drawing fonts. For the syntax of this option, check
5086 the "Color" section in the ffmpeg-utils manual.
5088 The default value of @var{fontcolor} is "black".
5090 @item fontcolor_expr
5091 String which is expanded the same way as @var{text} to obtain dynamic
5092 @var{fontcolor} value. By default this option has empty value and is not
5093 processed. When this option is set, it overrides @var{fontcolor} option.
5096 The font family to be used for drawing text. By default Sans.
5099 The font file to be used for drawing text. The path must be included.
5100 This parameter is mandatory if the fontconfig support is disabled.
5103 This option does not exist, please see the timeline system
5106 Draw the text applying alpha blending. The value can
5107 be either a number between 0.0 and 1.0
5108 The expression accepts the same variables @var{x, y} do.
5109 The default value is 1.
5110 Please see fontcolor_expr
5113 The font size to be used for drawing text.
5114 The default value of @var{fontsize} is 16.
5117 If set to 1, attempt to shape the text (for example, reverse the order of
5118 right-to-left text and join Arabic characters) before drawing it.
5119 Otherwise, just draw the text exactly as given.
5120 By default 1 (if supported).
5123 The flags to be used for loading the fonts.
5125 The flags map the corresponding flags supported by libfreetype, and are
5126 a combination of the following values:
5133 @item vertical_layout
5134 @item force_autohint
5137 @item ignore_global_advance_width
5139 @item ignore_transform
5145 Default value is "default".
5147 For more information consult the documentation for the FT_LOAD_*
5151 The color to be used for drawing a shadow behind the drawn text. For the
5152 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
5154 The default value of @var{shadowcolor} is "black".
5158 The x and y offsets for the text shadow position with respect to the
5159 position of the text. They can be either positive or negative
5160 values. The default value for both is "0".
5163 The starting frame number for the n/frame_num variable. The default value
5167 The size in number of spaces to use for rendering the tab.
5171 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
5172 format. It can be used with or without text parameter. @var{timecode_rate}
5173 option must be specified.
5175 @item timecode_rate, rate, r
5176 Set the timecode frame rate (timecode only).
5179 The text string to be drawn. The text must be a sequence of UTF-8
5181 This parameter is mandatory if no file is specified with the parameter
5185 A text file containing text to be drawn. The text must be a sequence
5186 of UTF-8 encoded characters.
5188 This parameter is mandatory if no text string is specified with the
5189 parameter @var{text}.
5191 If both @var{text} and @var{textfile} are specified, an error is thrown.
5194 If set to 1, the @var{textfile} will be reloaded before each frame.
5195 Be sure to update it atomically, or it may be read partially, or even fail.
5199 The expressions which specify the offsets where text will be drawn
5200 within the video frame. They are relative to the top/left border of the
5203 The default value of @var{x} and @var{y} is "0".
5205 See below for the list of accepted constants and functions.
5208 The parameters for @var{x} and @var{y} are expressions containing the
5209 following constants and functions:
5213 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
5217 horizontal and vertical chroma subsample values. For example for the
5218 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5221 the height of each text line
5229 @item max_glyph_a, ascent
5230 the maximum distance from the baseline to the highest/upper grid
5231 coordinate used to place a glyph outline point, for all the rendered
5233 It is a positive value, due to the grid's orientation with the Y axis
5236 @item max_glyph_d, descent
5237 the maximum distance from the baseline to the lowest grid coordinate
5238 used to place a glyph outline point, for all the rendered glyphs.
5239 This is a negative value, due to the grid's orientation, with the Y axis
5243 maximum glyph height, that is the maximum height for all the glyphs
5244 contained in the rendered text, it is equivalent to @var{ascent} -
5248 maximum glyph width, that is the maximum width for all the glyphs
5249 contained in the rendered text
5252 the number of input frame, starting from 0
5254 @item rand(min, max)
5255 return a random number included between @var{min} and @var{max}
5258 The input sample aspect ratio.
5261 timestamp expressed in seconds, NAN if the input timestamp is unknown
5264 the height of the rendered text
5267 the width of the rendered text
5271 the x and y offset coordinates where the text is drawn.
5273 These parameters allow the @var{x} and @var{y} expressions to refer
5274 each other, so you can for example specify @code{y=x/dar}.
5277 @anchor{drawtext_expansion}
5278 @subsection Text expansion
5280 If @option{expansion} is set to @code{strftime},
5281 the filter recognizes strftime() sequences in the provided text and
5282 expands them accordingly. Check the documentation of strftime(). This
5283 feature is deprecated.
5285 If @option{expansion} is set to @code{none}, the text is printed verbatim.
5287 If @option{expansion} is set to @code{normal} (which is the default),
5288 the following expansion mechanism is used.
5290 The backslash character @samp{\}, followed by any character, always expands to
5291 the second character.
5293 Sequence of the form @code{%@{...@}} are expanded. The text between the
5294 braces is a function name, possibly followed by arguments separated by ':'.
5295 If the arguments contain special characters or delimiters (':' or '@}'),
5296 they should be escaped.
5298 Note that they probably must also be escaped as the value for the
5299 @option{text} option in the filter argument string and as the filter
5300 argument in the filtergraph description, and possibly also for the shell,
5301 that makes up to four levels of escaping; using a text file avoids these
5304 The following functions are available:
5309 The expression evaluation result.
5311 It must take one argument specifying the expression to be evaluated,
5312 which accepts the same constants and functions as the @var{x} and
5313 @var{y} values. Note that not all constants should be used, for
5314 example the text size is not known when evaluating the expression, so
5315 the constants @var{text_w} and @var{text_h} will have an undefined
5318 @item expr_int_format, eif
5319 Evaluate the expression's value and output as formatted integer.
5321 The first argument is the expression to be evaluated, just as for the @var{expr} function.
5322 The second argument specifies the output format. Allowed values are @samp{x},
5323 @samp{X}, @samp{d} and @samp{u}. They are treated exactly as in the
5324 @code{printf} function.
5325 The third parameter is optional and sets the number of positions taken by the output.
5326 It can be used to add padding with zeros from the left.
5329 The time at which the filter is running, expressed in UTC.
5330 It can accept an argument: a strftime() format string.
5333 The time at which the filter is running, expressed in the local time zone.
5334 It can accept an argument: a strftime() format string.
5337 Frame metadata. It must take one argument specifying metadata key.
5340 The frame number, starting from 0.
5343 A 1 character description of the current picture type.
5346 The timestamp of the current frame.
5347 It can take up to two arguments.
5349 The first argument is the format of the timestamp; it defaults to @code{flt}
5350 for seconds as a decimal number with microsecond accuracy; @code{hms} stands
5351 for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy.
5353 The second argument is an offset added to the timestamp.
5357 @subsection Examples
5361 Draw "Test Text" with font FreeSerif, using the default values for the
5362 optional parameters.
5365 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
5369 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
5370 and y=50 (counting from the top-left corner of the screen), text is
5371 yellow with a red box around it. Both the text and the box have an
5375 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
5376 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
5379 Note that the double quotes are not necessary if spaces are not used
5380 within the parameter list.
5383 Show the text at the center of the video frame:
5385 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
5389 Show a text line sliding from right to left in the last row of the video
5390 frame. The file @file{LONG_LINE} is assumed to contain a single line
5393 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
5397 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
5399 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
5403 Draw a single green letter "g", at the center of the input video.
5404 The glyph baseline is placed at half screen height.
5406 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
5410 Show text for 1 second every 3 seconds:
5412 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
5416 Use fontconfig to set the font. Note that the colons need to be escaped.
5418 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
5422 Print the date of a real-time encoding (see strftime(3)):
5424 drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}'
5428 Show text fading in and out (appearing/disappearing):
5431 DS=1.0 # display start
5432 DE=10.0 # display end
5433 FID=1.5 # fade in duration
5434 FOD=5 # fade out duration
5435 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 @}"
5440 For more information about libfreetype, check:
5441 @url{http://www.freetype.org/}.
5443 For more information about fontconfig, check:
5444 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
5446 For more information about libfribidi, check:
5447 @url{http://fribidi.org/}.
5451 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
5453 The filter accepts the following options:
5458 Set low and high threshold values used by the Canny thresholding
5461 The high threshold selects the "strong" edge pixels, which are then
5462 connected through 8-connectivity with the "weak" edge pixels selected
5463 by the low threshold.
5465 @var{low} and @var{high} threshold values must be chosen in the range
5466 [0,1], and @var{low} should be lesser or equal to @var{high}.
5468 Default value for @var{low} is @code{20/255}, and default value for @var{high}
5472 Define the drawing mode.
5476 Draw white/gray wires on black background.
5479 Mix the colors to create a paint/cartoon effect.
5482 Default value is @var{wires}.
5485 @subsection Examples
5489 Standard edge detection with custom values for the hysteresis thresholding:
5491 edgedetect=low=0.1:high=0.4
5495 Painting effect without thresholding:
5497 edgedetect=mode=colormix:high=0
5502 Set brightness, contrast, saturation and approximate gamma adjustment.
5504 The filter accepts the following options:
5508 Set the contrast expression. The value must be a float value in range
5509 @code{-2.0} to @code{2.0}. The default value is "1".
5512 Set the brightness expression. The value must be a float value in
5513 range @code{-1.0} to @code{1.0}. The default value is "0".
5516 Set the saturation expression. The value must be a float in
5517 range @code{0.0} to @code{3.0}. The default value is "1".
5520 Set the gamma expression. The value must be a float in range
5521 @code{0.1} to @code{10.0}. The default value is "1".
5524 Set the gamma expression for red. The value must be a float in
5525 range @code{0.1} to @code{10.0}. The default value is "1".
5528 Set the gamma expression for green. The value must be a float in range
5529 @code{0.1} to @code{10.0}. The default value is "1".
5532 Set the gamma expression for blue. The value must be a float in range
5533 @code{0.1} to @code{10.0}. The default value is "1".
5536 Set the gamma weight expression. It can be used to reduce the effect
5537 of a high gamma value on bright image areas, e.g. keep them from
5538 getting overamplified and just plain white. The value must be a float
5539 in range @code{0.0} to @code{1.0}. A value of @code{0.0} turns the
5540 gamma correction all the way down while @code{1.0} leaves it at its
5541 full strength. Default is "1".
5544 Set when the expressions for brightness, contrast, saturation and
5545 gamma expressions are evaluated.
5547 It accepts the following values:
5550 only evaluate expressions once during the filter initialization or
5551 when a command is processed
5554 evaluate expressions for each incoming frame
5557 Default value is @samp{init}.
5560 The expressions accept the following parameters:
5563 frame count of the input frame starting from 0
5566 byte position of the corresponding packet in the input file, NAN if
5570 frame rate of the input video, NAN if the input frame rate is unknown
5573 timestamp expressed in seconds, NAN if the input timestamp is unknown
5576 @subsection Commands
5577 The filter supports the following commands:
5581 Set the contrast expression.
5584 Set the brightness expression.
5587 Set the saturation expression.
5590 Set the gamma expression.
5593 Set the gamma_r expression.
5596 Set gamma_g expression.
5599 Set gamma_b expression.
5602 Set gamma_weight expression.
5604 The command accepts the same syntax of the corresponding option.
5606 If the specified expression is not valid, it is kept at its current
5613 Apply erosion effect to the video.
5615 This filter replaces the pixel by the local(3x3) minimum.
5617 It accepts the following options:
5624 Allows to limit the maximum change for each plane, default is 65535.
5625 If 0, plane will remain unchanged.
5628 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
5631 Flags to local 3x3 coordinates maps like this:
5638 @section extractplanes
5640 Extract color channel components from input video stream into
5641 separate grayscale video streams.
5643 The filter accepts the following option:
5647 Set plane(s) to extract.
5649 Available values for planes are:
5660 Choosing planes not available in the input will result in an error.
5661 That means you cannot select @code{r}, @code{g}, @code{b} planes
5662 with @code{y}, @code{u}, @code{v} planes at same time.
5665 @subsection Examples
5669 Extract luma, u and v color channel component from input video frame
5670 into 3 grayscale outputs:
5672 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
5678 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
5680 For each input image, the filter will compute the optimal mapping from
5681 the input to the output given the codebook length, that is the number
5682 of distinct output colors.
5684 This filter accepts the following options.
5687 @item codebook_length, l
5688 Set codebook length. The value must be a positive integer, and
5689 represents the number of distinct output colors. Default value is 256.
5692 Set the maximum number of iterations to apply for computing the optimal
5693 mapping. The higher the value the better the result and the higher the
5694 computation time. Default value is 1.
5697 Set a random seed, must be an integer included between 0 and
5698 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
5699 will try to use a good random seed on a best effort basis.
5702 Set pal8 output pixel format. This option does not work with codebook
5703 length greater than 256.
5708 Apply a fade-in/out effect to the input video.
5710 It accepts the following parameters:
5714 The effect type can be either "in" for a fade-in, or "out" for a fade-out
5716 Default is @code{in}.
5718 @item start_frame, s
5719 Specify the number of the frame to start applying the fade
5720 effect at. Default is 0.
5723 The number of frames that the fade effect lasts. At the end of the
5724 fade-in effect, the output video will have the same intensity as the input video.
5725 At the end of the fade-out transition, the output video will be filled with the
5726 selected @option{color}.
5730 If set to 1, fade only alpha channel, if one exists on the input.
5733 @item start_time, st
5734 Specify the timestamp (in seconds) of the frame to start to apply the fade
5735 effect. If both start_frame and start_time are specified, the fade will start at
5736 whichever comes last. Default is 0.
5739 The number of seconds for which the fade effect has to last. At the end of the
5740 fade-in effect the output video will have the same intensity as the input video,
5741 at the end of the fade-out transition the output video will be filled with the
5742 selected @option{color}.
5743 If both duration and nb_frames are specified, duration is used. Default is 0
5744 (nb_frames is used by default).
5747 Specify the color of the fade. Default is "black".
5750 @subsection Examples
5754 Fade in the first 30 frames of video:
5759 The command above is equivalent to:
5765 Fade out the last 45 frames of a 200-frame video:
5768 fade=type=out:start_frame=155:nb_frames=45
5772 Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
5774 fade=in:0:25, fade=out:975:25
5778 Make the first 5 frames yellow, then fade in from frame 5-24:
5780 fade=in:5:20:color=yellow
5784 Fade in alpha over first 25 frames of video:
5786 fade=in:0:25:alpha=1
5790 Make the first 5.5 seconds black, then fade in for 0.5 seconds:
5792 fade=t=in:st=5.5:d=0.5
5798 Apply arbitrary expressions to samples in frequency domain
5802 Adjust the dc value (gain) of the luma plane of the image. The filter
5803 accepts an integer value in range @code{0} to @code{1000}. The default
5804 value is set to @code{0}.
5807 Adjust the dc value (gain) of the 1st chroma plane of the image. The
5808 filter accepts an integer value in range @code{0} to @code{1000}. The
5809 default value is set to @code{0}.
5812 Adjust the dc value (gain) of the 2nd chroma plane of the image. The
5813 filter accepts an integer value in range @code{0} to @code{1000}. The
5814 default value is set to @code{0}.
5817 Set the frequency domain weight expression for the luma plane.
5820 Set the frequency domain weight expression for the 1st chroma plane.
5823 Set the frequency domain weight expression for the 2nd chroma plane.
5825 The filter accepts the following variables:
5828 The coordinates of the current sample.
5832 The width and height of the image.
5835 @subsection Examples
5841 fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
5847 fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
5853 fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
5860 Extract a single field from an interlaced image using stride
5861 arithmetic to avoid wasting CPU time. The output frames are marked as
5864 The filter accepts the following options:
5868 Specify whether to extract the top (if the value is @code{0} or
5869 @code{top}) or the bottom field (if the value is @code{1} or
5875 Field matching filter for inverse telecine. It is meant to reconstruct the
5876 progressive frames from a telecined stream. The filter does not drop duplicated
5877 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
5878 followed by a decimation filter such as @ref{decimate} in the filtergraph.
5880 The separation of the field matching and the decimation is notably motivated by
5881 the possibility of inserting a de-interlacing filter fallback between the two.
5882 If the source has mixed telecined and real interlaced content,
5883 @code{fieldmatch} will not be able to match fields for the interlaced parts.
5884 But these remaining combed frames will be marked as interlaced, and thus can be
5885 de-interlaced by a later filter such as @ref{yadif} before decimation.
5887 In addition to the various configuration options, @code{fieldmatch} can take an
5888 optional second stream, activated through the @option{ppsrc} option. If
5889 enabled, the frames reconstruction will be based on the fields and frames from
5890 this second stream. This allows the first input to be pre-processed in order to
5891 help the various algorithms of the filter, while keeping the output lossless
5892 (assuming the fields are matched properly). Typically, a field-aware denoiser,
5893 or brightness/contrast adjustments can help.
5895 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
5896 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
5897 which @code{fieldmatch} is based on. While the semantic and usage are very
5898 close, some behaviour and options names can differ.
5900 The @ref{decimate} filter currently only works for constant frame rate input.
5901 If your input has mixed telecined (30fps) and progressive content with a lower
5902 framerate like 24fps use the following filterchain to produce the necessary cfr
5903 stream: @code{dejudder,fps=30000/1001,fieldmatch,decimate}.
5905 The filter accepts the following options:
5909 Specify the assumed field order of the input stream. Available values are:
5913 Auto detect parity (use FFmpeg's internal parity value).
5915 Assume bottom field first.
5917 Assume top field first.
5920 Note that it is sometimes recommended not to trust the parity announced by the
5923 Default value is @var{auto}.
5926 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
5927 sense that it won't risk creating jerkiness due to duplicate frames when
5928 possible, but if there are bad edits or blended fields it will end up
5929 outputting combed frames when a good match might actually exist. On the other
5930 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
5931 but will almost always find a good frame if there is one. The other values are
5932 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
5933 jerkiness and creating duplicate frames versus finding good matches in sections
5934 with bad edits, orphaned fields, blended fields, etc.
5936 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
5938 Available values are:
5942 2-way matching (p/c)
5944 2-way matching, and trying 3rd match if still combed (p/c + n)
5946 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
5948 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
5949 still combed (p/c + n + u/b)
5951 3-way matching (p/c/n)
5953 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
5954 detected as combed (p/c/n + u/b)
5957 The parenthesis at the end indicate the matches that would be used for that
5958 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
5961 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
5964 Default value is @var{pc_n}.
5967 Mark the main input stream as a pre-processed input, and enable the secondary
5968 input stream as the clean source to pick the fields from. See the filter
5969 introduction for more details. It is similar to the @option{clip2} feature from
5972 Default value is @code{0} (disabled).
5975 Set the field to match from. It is recommended to set this to the same value as
5976 @option{order} unless you experience matching failures with that setting. In
5977 certain circumstances changing the field that is used to match from can have a
5978 large impact on matching performance. Available values are:
5982 Automatic (same value as @option{order}).
5984 Match from the bottom field.
5986 Match from the top field.
5989 Default value is @var{auto}.
5992 Set whether or not chroma is included during the match comparisons. In most
5993 cases it is recommended to leave this enabled. You should set this to @code{0}
5994 only if your clip has bad chroma problems such as heavy rainbowing or other
5995 artifacts. Setting this to @code{0} could also be used to speed things up at
5996 the cost of some accuracy.
5998 Default value is @code{1}.
6002 These define an exclusion band which excludes the lines between @option{y0} and
6003 @option{y1} from being included in the field matching decision. An exclusion
6004 band can be used to ignore subtitles, a logo, or other things that may
6005 interfere with the matching. @option{y0} sets the starting scan line and
6006 @option{y1} sets the ending line; all lines in between @option{y0} and
6007 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
6008 @option{y0} and @option{y1} to the same value will disable the feature.
6009 @option{y0} and @option{y1} defaults to @code{0}.
6012 Set the scene change detection threshold as a percentage of maximum change on
6013 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
6014 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
6015 @option{scthresh} is @code{[0.0, 100.0]}.
6017 Default value is @code{12.0}.
6020 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
6021 account the combed scores of matches when deciding what match to use as the
6022 final match. Available values are:
6026 No final matching based on combed scores.
6028 Combed scores are only used when a scene change is detected.
6030 Use combed scores all the time.
6033 Default is @var{sc}.
6036 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
6037 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
6038 Available values are:
6042 No forced calculation.
6044 Force p/c/n calculations.
6046 Force p/c/n/u/b calculations.
6049 Default value is @var{none}.
6052 This is the area combing threshold used for combed frame detection. This
6053 essentially controls how "strong" or "visible" combing must be to be detected.
6054 Larger values mean combing must be more visible and smaller values mean combing
6055 can be less visible or strong and still be detected. Valid settings are from
6056 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
6057 be detected as combed). This is basically a pixel difference value. A good
6058 range is @code{[8, 12]}.
6060 Default value is @code{9}.
6063 Sets whether or not chroma is considered in the combed frame decision. Only
6064 disable this if your source has chroma problems (rainbowing, etc.) that are
6065 causing problems for the combed frame detection with chroma enabled. Actually,
6066 using @option{chroma}=@var{0} is usually more reliable, except for the case
6067 where there is chroma only combing in the source.
6069 Default value is @code{0}.
6073 Respectively set the x-axis and y-axis size of the window used during combed
6074 frame detection. This has to do with the size of the area in which
6075 @option{combpel} pixels are required to be detected as combed for a frame to be
6076 declared combed. See the @option{combpel} parameter description for more info.
6077 Possible values are any number that is a power of 2 starting at 4 and going up
6080 Default value is @code{16}.
6083 The number of combed pixels inside any of the @option{blocky} by
6084 @option{blockx} size blocks on the frame for the frame to be detected as
6085 combed. While @option{cthresh} controls how "visible" the combing must be, this
6086 setting controls "how much" combing there must be in any localized area (a
6087 window defined by the @option{blockx} and @option{blocky} settings) on the
6088 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
6089 which point no frames will ever be detected as combed). This setting is known
6090 as @option{MI} in TFM/VFM vocabulary.
6092 Default value is @code{80}.
6095 @anchor{p/c/n/u/b meaning}
6096 @subsection p/c/n/u/b meaning
6098 @subsubsection p/c/n
6100 We assume the following telecined stream:
6103 Top fields: 1 2 2 3 4
6104 Bottom fields: 1 2 3 4 4
6107 The numbers correspond to the progressive frame the fields relate to. Here, the
6108 first two frames are progressive, the 3rd and 4th are combed, and so on.
6110 When @code{fieldmatch} is configured to run a matching from bottom
6111 (@option{field}=@var{bottom}) this is how this input stream get transformed:
6116 B 1 2 3 4 4 <-- matching reference
6125 As a result of the field matching, we can see that some frames get duplicated.
6126 To perform a complete inverse telecine, you need to rely on a decimation filter
6127 after this operation. See for instance the @ref{decimate} filter.
6129 The same operation now matching from top fields (@option{field}=@var{top})
6134 T 1 2 2 3 4 <-- matching reference
6144 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
6145 basically, they refer to the frame and field of the opposite parity:
6148 @item @var{p} matches the field of the opposite parity in the previous frame
6149 @item @var{c} matches the field of the opposite parity in the current frame
6150 @item @var{n} matches the field of the opposite parity in the next frame
6155 The @var{u} and @var{b} matching are a bit special in the sense that they match
6156 from the opposite parity flag. In the following examples, we assume that we are
6157 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
6158 'x' is placed above and below each matched fields.
6160 With bottom matching (@option{field}=@var{bottom}):
6165 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6166 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6174 With top matching (@option{field}=@var{top}):
6179 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6180 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6188 @subsection Examples
6190 Simple IVTC of a top field first telecined stream:
6192 fieldmatch=order=tff:combmatch=none, decimate
6195 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
6197 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
6202 Transform the field order of the input video.
6204 It accepts the following parameters:
6209 The output field order. Valid values are @var{tff} for top field first or @var{bff}
6210 for bottom field first.
6213 The default value is @samp{tff}.
6215 The transformation is done by shifting the picture content up or down
6216 by one line, and filling the remaining line with appropriate picture content.
6217 This method is consistent with most broadcast field order converters.
6219 If the input video is not flagged as being interlaced, or it is already
6220 flagged as being of the required output field order, then this filter does
6221 not alter the incoming video.
6223 It is very useful when converting to or from PAL DV material,
6224 which is bottom field first.
6228 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
6233 Buffer input images and send them when they are requested.
6235 It is mainly useful when auto-inserted by the libavfilter
6238 It does not take parameters.
6242 Find a rectangular object
6244 It accepts the following options:
6248 Filepath of the object image, needs to be in gray8.
6251 Detection threshold, default is 0.5.
6254 Number of mipmaps, default is 3.
6256 @item xmin, ymin, xmax, ymax
6257 Specifies the rectangle in which to search.
6260 @subsection Examples
6264 Generate a representative palette of a given video using @command{ffmpeg}:
6266 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6272 Cover a rectangular object
6274 It accepts the following options:
6278 Filepath of the optional cover image, needs to be in yuv420.
6283 It accepts the following values:
6286 cover it by the supplied image
6288 cover it by interpolating the surrounding pixels
6291 Default value is @var{blur}.
6294 @subsection Examples
6298 Generate a representative palette of a given video using @command{ffmpeg}:
6300 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6307 Convert the input video to one of the specified pixel formats.
6308 Libavfilter will try to pick one that is suitable as input to
6311 It accepts the following parameters:
6315 A '|'-separated list of pixel format names, such as
6316 "pix_fmts=yuv420p|monow|rgb24".
6320 @subsection Examples
6324 Convert the input video to the @var{yuv420p} format
6326 format=pix_fmts=yuv420p
6329 Convert the input video to any of the formats in the list
6331 format=pix_fmts=yuv420p|yuv444p|yuv410p
6338 Convert the video to specified constant frame rate by duplicating or dropping
6339 frames as necessary.
6341 It accepts the following parameters:
6345 The desired output frame rate. The default is @code{25}.
6350 Possible values are:
6353 zero round towards 0
6357 round towards -infinity
6359 round towards +infinity
6363 The default is @code{near}.
6366 Assume the first PTS should be the given value, in seconds. This allows for
6367 padding/trimming at the start of stream. By default, no assumption is made
6368 about the first frame's expected PTS, so no padding or trimming is done.
6369 For example, this could be set to 0 to pad the beginning with duplicates of
6370 the first frame if a video stream starts after the audio stream or to trim any
6371 frames with a negative PTS.
6375 Alternatively, the options can be specified as a flat string:
6376 @var{fps}[:@var{round}].
6378 See also the @ref{setpts} filter.
6380 @subsection Examples
6384 A typical usage in order to set the fps to 25:
6390 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
6392 fps=fps=film:round=near
6398 Pack two different video streams into a stereoscopic video, setting proper
6399 metadata on supported codecs. The two views should have the same size and
6400 framerate and processing will stop when the shorter video ends. Please note
6401 that you may conveniently adjust view properties with the @ref{scale} and
6404 It accepts the following parameters:
6408 The desired packing format. Supported values are:
6413 The views are next to each other (default).
6416 The views are on top of each other.
6419 The views are packed by line.
6422 The views are packed by column.
6425 The views are temporally interleaved.
6434 # Convert left and right views into a frame-sequential video
6435 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
6437 # Convert views into a side-by-side video with the same output resolution as the input
6438 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
6443 Change the frame rate by interpolating new video output frames from the source
6446 This filter is not designed to function correctly with interlaced media. If
6447 you wish to change the frame rate of interlaced media then you are required
6448 to deinterlace before this filter and re-interlace after this filter.
6450 A description of the accepted options follows.
6454 Specify the output frames per second. This option can also be specified
6455 as a value alone. The default is @code{50}.
6458 Specify the start of a range where the output frame will be created as a
6459 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6460 the default is @code{15}.
6463 Specify the end of a range where the output frame will be created as a
6464 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6465 the default is @code{240}.
6468 Specify the level at which a scene change is detected as a value between
6469 0 and 100 to indicate a new scene; a low value reflects a low
6470 probability for the current frame to introduce a new scene, while a higher
6471 value means the current frame is more likely to be one.
6472 The default is @code{7}.
6475 Specify flags influencing the filter process.
6477 Available value for @var{flags} is:
6480 @item scene_change_detect, scd
6481 Enable scene change detection using the value of the option @var{scene}.
6482 This flag is enabled by default.
6488 Select one frame every N-th frame.
6490 This filter accepts the following option:
6493 Select frame after every @code{step} frames.
6494 Allowed values are positive integers higher than 0. Default value is @code{1}.
6500 Apply a frei0r effect to the input video.
6502 To enable the compilation of this filter, you need to install the frei0r
6503 header and configure FFmpeg with @code{--enable-frei0r}.
6505 It accepts the following parameters:
6510 The name of the frei0r effect to load. If the environment variable
6511 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
6512 directories specified by the colon-separated list in @env{FREIOR_PATH}.
6513 Otherwise, the standard frei0r paths are searched, in this order:
6514 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
6515 @file{/usr/lib/frei0r-1/}.
6518 A '|'-separated list of parameters to pass to the frei0r effect.
6522 A frei0r effect parameter can be a boolean (its value is either
6523 "y" or "n"), a double, a color (specified as
6524 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
6525 numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
6526 section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where
6527 @var{X} and @var{Y} are floating point numbers) and/or a string.
6529 The number and types of parameters depend on the loaded effect. If an
6530 effect parameter is not specified, the default value is set.
6532 @subsection Examples
6536 Apply the distort0r effect, setting the first two double parameters:
6538 frei0r=filter_name=distort0r:filter_params=0.5|0.01
6542 Apply the colordistance effect, taking a color as the first parameter:
6544 frei0r=colordistance:0.2/0.3/0.4
6545 frei0r=colordistance:violet
6546 frei0r=colordistance:0x112233
6550 Apply the perspective effect, specifying the top left and top right image
6553 frei0r=perspective:0.2/0.2|0.8/0.2
6557 For more information, see
6558 @url{http://frei0r.dyne.org}
6562 Apply fast and simple postprocessing. It is a faster version of @ref{spp}.
6564 It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
6565 processing filter, one of them is performed once per block, not per pixel.
6566 This allows for much higher speed.
6568 The filter accepts the following options:
6572 Set quality. This option defines the number of levels for averaging. It accepts
6573 an integer in the range 4-5. Default value is @code{4}.
6576 Force a constant quantization parameter. It accepts an integer in range 0-63.
6577 If not set, the filter will use the QP from the video stream (if available).
6580 Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
6581 more details but also more artifacts, while higher values make the image smoother
6582 but also blurrier. Default value is @code{0} − PSNR optimal.
6585 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
6586 option may cause flicker since the B-Frames have often larger QP. Default is
6587 @code{0} (not enabled).
6593 The filter accepts the following options:
6597 Set the luminance expression.
6599 Set the chrominance blue expression.
6601 Set the chrominance red expression.
6603 Set the alpha expression.
6605 Set the red expression.
6607 Set the green expression.
6609 Set the blue expression.
6612 The colorspace is selected according to the specified options. If one
6613 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
6614 options is specified, the filter will automatically select a YCbCr
6615 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
6616 @option{blue_expr} options is specified, it will select an RGB
6619 If one of the chrominance expression is not defined, it falls back on the other
6620 one. If no alpha expression is specified it will evaluate to opaque value.
6621 If none of chrominance expressions are specified, they will evaluate
6622 to the luminance expression.
6624 The expressions can use the following variables and functions:
6628 The sequential number of the filtered frame, starting from @code{0}.
6632 The coordinates of the current sample.
6636 The width and height of the image.
6640 Width and height scale depending on the currently filtered plane. It is the
6641 ratio between the corresponding luma plane number of pixels and the current
6642 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
6643 @code{0.5,0.5} for chroma planes.
6646 Time of the current frame, expressed in seconds.
6649 Return the value of the pixel at location (@var{x},@var{y}) of the current
6653 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
6657 Return the value of the pixel at location (@var{x},@var{y}) of the
6658 blue-difference chroma plane. Return 0 if there is no such plane.
6661 Return the value of the pixel at location (@var{x},@var{y}) of the
6662 red-difference chroma plane. Return 0 if there is no such plane.
6667 Return the value of the pixel at location (@var{x},@var{y}) of the
6668 red/green/blue component. Return 0 if there is no such component.
6671 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
6672 plane. Return 0 if there is no such plane.
6675 For functions, if @var{x} and @var{y} are outside the area, the value will be
6676 automatically clipped to the closer edge.
6678 @subsection Examples
6682 Flip the image horizontally:
6688 Generate a bidimensional sine wave, with angle @code{PI/3} and a
6689 wavelength of 100 pixels:
6691 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
6695 Generate a fancy enigmatic moving light:
6697 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
6701 Generate a quick emboss effect:
6703 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
6707 Modify RGB components depending on pixel position:
6709 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
6713 Create a radial gradient that is the same size as the input (also see
6714 the @ref{vignette} filter):
6716 geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
6720 Create a linear gradient to use as a mask for another filter, then
6721 compose with @ref{overlay}. In this example the video will gradually
6722 become more blurry from the top to the bottom of the y-axis as defined
6723 by the linear gradient:
6725 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
6731 Fix the banding artifacts that are sometimes introduced into nearly flat
6732 regions by truncation to 8bit color depth.
6733 Interpolate the gradients that should go where the bands are, and
6736 It is designed for playback only. Do not use it prior to
6737 lossy compression, because compression tends to lose the dither and
6738 bring back the bands.
6740 It accepts the following parameters:
6745 The maximum amount by which the filter will change any one pixel. This is also
6746 the threshold for detecting nearly flat regions. Acceptable values range from
6747 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
6751 The neighborhood to fit the gradient to. A larger radius makes for smoother
6752 gradients, but also prevents the filter from modifying the pixels near detailed
6753 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
6754 values will be clipped to the valid range.
6758 Alternatively, the options can be specified as a flat string:
6759 @var{strength}[:@var{radius}]
6761 @subsection Examples
6765 Apply the filter with a @code{3.5} strength and radius of @code{8}:
6771 Specify radius, omitting the strength (which will fall-back to the default
6782 Apply a Hald CLUT to a video stream.
6784 First input is the video stream to process, and second one is the Hald CLUT.
6785 The Hald CLUT input can be a simple picture or a complete video stream.
6787 The filter accepts the following options:
6791 Force termination when the shortest input terminates. Default is @code{0}.
6793 Continue applying the last CLUT after the end of the stream. A value of
6794 @code{0} disable the filter after the last frame of the CLUT is reached.
6795 Default is @code{1}.
6798 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
6799 filters share the same internals).
6801 More information about the Hald CLUT can be found on Eskil Steenberg's website
6802 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
6804 @subsection Workflow examples
6806 @subsubsection Hald CLUT video stream
6808 Generate an identity Hald CLUT stream altered with various effects:
6810 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
6813 Note: make sure you use a lossless codec.
6815 Then use it with @code{haldclut} to apply it on some random stream:
6817 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
6820 The Hald CLUT will be applied to the 10 first seconds (duration of
6821 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
6822 to the remaining frames of the @code{mandelbrot} stream.
6824 @subsubsection Hald CLUT with preview
6826 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
6827 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
6828 biggest possible square starting at the top left of the picture. The remaining
6829 padding pixels (bottom or right) will be ignored. This area can be used to add
6830 a preview of the Hald CLUT.
6832 Typically, the following generated Hald CLUT will be supported by the
6833 @code{haldclut} filter:
6836 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
6837 pad=iw+320 [padded_clut];
6838 smptebars=s=320x256, split [a][b];
6839 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
6840 [main][b] overlay=W-320" -frames:v 1 clut.png
6843 It contains the original and a preview of the effect of the CLUT: SMPTE color
6844 bars are displayed on the right-top, and below the same color bars processed by
6847 Then, the effect of this Hald CLUT can be visualized with:
6849 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
6854 Flip the input video horizontally.
6856 For example, to horizontally flip the input video with @command{ffmpeg}:
6858 ffmpeg -i in.avi -vf "hflip" out.avi
6862 This filter applies a global color histogram equalization on a
6865 It can be used to correct video that has a compressed range of pixel
6866 intensities. The filter redistributes the pixel intensities to
6867 equalize their distribution across the intensity range. It may be
6868 viewed as an "automatically adjusting contrast filter". This filter is
6869 useful only for correcting degraded or poorly captured source
6872 The filter accepts the following options:
6876 Determine the amount of equalization to be applied. As the strength
6877 is reduced, the distribution of pixel intensities more-and-more
6878 approaches that of the input frame. The value must be a float number
6879 in the range [0,1] and defaults to 0.200.
6882 Set the maximum intensity that can generated and scale the output
6883 values appropriately. The strength should be set as desired and then
6884 the intensity can be limited if needed to avoid washing-out. The value
6885 must be a float number in the range [0,1] and defaults to 0.210.
6888 Set the antibanding level. If enabled the filter will randomly vary
6889 the luminance of output pixels by a small amount to avoid banding of
6890 the histogram. Possible values are @code{none}, @code{weak} or
6891 @code{strong}. It defaults to @code{none}.
6896 Compute and draw a color distribution histogram for the input video.
6898 The computed histogram is a representation of the color component
6899 distribution in an image.
6901 The filter accepts the following options:
6907 It accepts the following values:
6910 Standard histogram that displays the color components distribution in an
6911 image. Displays color graph for each color component. Shows distribution of
6912 the Y, U, V, A or R, G, B components, depending on input format, in the
6913 current frame. Below each graph a color component scale meter is shown.
6916 Displays chroma values (U/V color placement) in a two dimensional
6917 graph (which is called a vectorscope). The brighter a pixel in the
6918 vectorscope, the more pixels of the input frame correspond to that pixel
6919 (i.e., more pixels have this chroma value). The V component is displayed on
6920 the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost
6921 side being V = 255. The U component is displayed on the vertical (Y) axis,
6922 with the top representing U = 0 and the bottom representing U = 255.
6924 The position of a white pixel in the graph corresponds to the chroma value of
6925 a pixel of the input clip. The graph can therefore be used to read the hue
6926 (color flavor) and the saturation (the dominance of the hue in the color). As
6927 the hue of a color changes, it moves around the square. At the center of the
6928 square the saturation is zero, which means that the corresponding pixel has no
6929 color. If the amount of a specific color is increased (while leaving the other
6930 colors unchanged) the saturation increases, and the indicator moves towards
6931 the edge of the square.
6934 Chroma values in vectorscope, similar as @code{color} but actual chroma values
6938 Per row/column color component graph. In row mode, the graph on the left side
6939 represents color component value 0 and the right side represents value = 255.
6940 In column mode, the top side represents color component value = 0 and bottom
6941 side represents value = 255.
6943 Default value is @code{levels}.
6946 Set height of level in @code{levels}. Default value is @code{200}.
6947 Allowed range is [50, 2048].
6950 Set height of color scale in @code{levels}. Default value is @code{12}.
6951 Allowed range is [0, 40].
6954 Set step for @code{waveform} mode. Smaller values are useful to find out how
6955 many values of the same luminance are distributed across input rows/columns.
6956 Default value is @code{10}. Allowed range is [1, 255].
6959 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
6960 Default is @code{row}.
6962 @item waveform_mirror
6963 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
6964 means mirrored. In mirrored mode, higher values will be represented on the left
6965 side for @code{row} mode and at the top for @code{column} mode. Default is
6966 @code{0} (unmirrored).
6969 Set display mode for @code{waveform} and @code{levels}.
6970 It accepts the following values:
6973 Display separate graph for the color components side by side in
6974 @code{row} waveform mode or one below the other in @code{column} waveform mode
6975 for @code{waveform} histogram mode. For @code{levels} histogram mode,
6976 per color component graphs are placed below each other.
6978 Using this display mode in @code{waveform} histogram mode makes it easy to
6979 spot color casts in the highlights and shadows of an image, by comparing the
6980 contours of the top and the bottom graphs of each waveform. Since whites,
6981 grays, and blacks are characterized by exactly equal amounts of red, green,
6982 and blue, neutral areas of the picture should display three waveforms of
6983 roughly equal width/height. If not, the correction is easy to perform by
6984 making level adjustments the three waveforms.
6987 Presents information identical to that in the @code{parade}, except
6988 that the graphs representing color components are superimposed directly
6991 This display mode in @code{waveform} histogram mode makes it easier to spot
6992 relative differences or similarities in overlapping areas of the color
6993 components that are supposed to be identical, such as neutral whites, grays,
6996 Default is @code{parade}.
6999 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
7000 Default is @code{linear}.
7003 Set what color components to display for mode @code{levels}.
7004 Default is @code{7}.
7007 @subsection Examples
7012 Calculate and draw histogram:
7014 ffplay -i input -vf histogram
7022 This is a high precision/quality 3d denoise filter. It aims to reduce
7023 image noise, producing smooth images and making still images really
7024 still. It should enhance compressibility.
7026 It accepts the following optional parameters:
7030 A non-negative floating point number which specifies spatial luma strength.
7033 @item chroma_spatial
7034 A non-negative floating point number which specifies spatial chroma strength.
7035 It defaults to 3.0*@var{luma_spatial}/4.0.
7038 A floating point number which specifies luma temporal strength. It defaults to
7039 6.0*@var{luma_spatial}/4.0.
7042 A floating point number which specifies chroma temporal strength. It defaults to
7043 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
7048 Apply a high-quality magnification filter designed for pixel art. This filter
7049 was originally created by Maxim Stepin.
7051 It accepts the following option:
7055 Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
7056 @code{hq3x} and @code{4} for @code{hq4x}.
7057 Default is @code{3}.
7061 Stack input videos horizontally.
7063 All streams must be of same pixel format and of same height.
7065 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
7066 to create same output.
7068 The filter accept the following option:
7072 Set number of input streams. Default is 2.
7077 Modify the hue and/or the saturation of the input.
7079 It accepts the following parameters:
7083 Specify the hue angle as a number of degrees. It accepts an expression,
7084 and defaults to "0".
7087 Specify the saturation in the [-10,10] range. It accepts an expression and
7091 Specify the hue angle as a number of radians. It accepts an
7092 expression, and defaults to "0".
7095 Specify the brightness in the [-10,10] range. It accepts an expression and
7099 @option{h} and @option{H} are mutually exclusive, and can't be
7100 specified at the same time.
7102 The @option{b}, @option{h}, @option{H} and @option{s} option values are
7103 expressions containing the following constants:
7107 frame count of the input frame starting from 0
7110 presentation timestamp of the input frame expressed in time base units
7113 frame rate of the input video, NAN if the input frame rate is unknown
7116 timestamp expressed in seconds, NAN if the input timestamp is unknown
7119 time base of the input video
7122 @subsection Examples
7126 Set the hue to 90 degrees and the saturation to 1.0:
7132 Same command but expressing the hue in radians:
7138 Rotate hue and make the saturation swing between 0
7139 and 2 over a period of 1 second:
7141 hue="H=2*PI*t: s=sin(2*PI*t)+1"
7145 Apply a 3 seconds saturation fade-in effect starting at 0:
7150 The general fade-in expression can be written as:
7152 hue="s=min(0\, max((t-START)/DURATION\, 1))"
7156 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
7158 hue="s=max(0\, min(1\, (8-t)/3))"
7161 The general fade-out expression can be written as:
7163 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
7168 @subsection Commands
7170 This filter supports the following commands:
7176 Modify the hue and/or the saturation and/or brightness of the input video.
7177 The command accepts the same syntax of the corresponding option.
7179 If the specified expression is not valid, it is kept at its current
7185 Detect video interlacing type.
7187 This filter tries to detect if the input frames as interlaced, progressive,
7188 top or bottom field first. It will also try and detect fields that are
7189 repeated between adjacent frames (a sign of telecine).
7191 Single frame detection considers only immediately adjacent frames when classifying each frame.
7192 Multiple frame detection incorporates the classification history of previous frames.
7194 The filter will log these metadata values:
7197 @item single.current_frame
7198 Detected type of current frame using single-frame detection. One of:
7199 ``tff'' (top field first), ``bff'' (bottom field first),
7200 ``progressive'', or ``undetermined''
7203 Cumulative number of frames detected as top field first using single-frame detection.
7206 Cumulative number of frames detected as top field first using multiple-frame detection.
7209 Cumulative number of frames detected as bottom field first using single-frame detection.
7211 @item multiple.current_frame
7212 Detected type of current frame using multiple-frame detection. One of:
7213 ``tff'' (top field first), ``bff'' (bottom field first),
7214 ``progressive'', or ``undetermined''
7217 Cumulative number of frames detected as bottom field first using multiple-frame detection.
7219 @item single.progressive
7220 Cumulative number of frames detected as progressive using single-frame detection.
7222 @item multiple.progressive
7223 Cumulative number of frames detected as progressive using multiple-frame detection.
7225 @item single.undetermined
7226 Cumulative number of frames that could not be classified using single-frame detection.
7228 @item multiple.undetermined
7229 Cumulative number of frames that could not be classified using multiple-frame detection.
7231 @item repeated.current_frame
7232 Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''.
7234 @item repeated.neither
7235 Cumulative number of frames with no repeated field.
7238 Cumulative number of frames with the top field repeated from the previous frame's top field.
7240 @item repeated.bottom
7241 Cumulative number of frames with the bottom field repeated from the previous frame's bottom field.
7244 The filter accepts the following options:
7248 Set interlacing threshold.
7250 Set progressive threshold.
7252 Threshold for repeated field detection.
7254 Number of frames after which a given frame's contribution to the
7255 statistics is halved (i.e., it contributes only 0.5 to it's
7256 classification). The default of 0 means that all frames seen are given
7257 full weight of 1.0 forever.
7258 @item analyze_interlaced_flag
7259 When this is not 0 then idet will use the specified number of frames to determine
7260 if the interlaced flag is accurate, it will not count undetermined frames.
7261 If the flag is found to be accurate it will be used without any further
7262 computations, if it is found to be inaccurate it will be cleared without any
7263 further computations. This allows inserting the idet filter as a low computational
7264 method to clean up the interlaced flag
7269 Deinterleave or interleave fields.
7271 This filter allows one to process interlaced images fields without
7272 deinterlacing them. Deinterleaving splits the input frame into 2
7273 fields (so called half pictures). Odd lines are moved to the top
7274 half of the output image, even lines to the bottom half.
7275 You can process (filter) them independently and then re-interleave them.
7277 The filter accepts the following options:
7281 @item chroma_mode, c
7283 Available values for @var{luma_mode}, @var{chroma_mode} and
7284 @var{alpha_mode} are:
7290 @item deinterleave, d
7291 Deinterleave fields, placing one above the other.
7294 Interleave fields. Reverse the effect of deinterleaving.
7296 Default value is @code{none}.
7299 @item chroma_swap, cs
7300 @item alpha_swap, as
7301 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
7306 Apply inflate effect to the video.
7308 This filter replaces the pixel by the local(3x3) average by taking into account
7309 only values higher than the pixel.
7311 It accepts the following options:
7318 Allows to limit the maximum change for each plane, default is 65535.
7319 If 0, plane will remain unchanged.
7324 Simple interlacing filter from progressive contents. This interleaves upper (or
7325 lower) lines from odd frames with lower (or upper) lines from even frames,
7326 halving the frame rate and preserving image height.
7329 Original Original New Frame
7330 Frame 'j' Frame 'j+1' (tff)
7331 ========== =========== ==================
7332 Line 0 --------------------> Frame 'j' Line 0
7333 Line 1 Line 1 ----> Frame 'j+1' Line 1
7334 Line 2 ---------------------> Frame 'j' Line 2
7335 Line 3 Line 3 ----> Frame 'j+1' Line 3
7337 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
7340 It accepts the following optional parameters:
7344 This determines whether the interlaced frame is taken from the even
7345 (tff - default) or odd (bff) lines of the progressive frame.
7348 Enable (default) or disable the vertical lowpass filter to avoid twitter
7349 interlacing and reduce moire patterns.
7354 Deinterlace input video by applying Donald Graft's adaptive kernel
7355 deinterling. Work on interlaced parts of a video to produce
7358 The description of the accepted parameters follows.
7362 Set the threshold which affects the filter's tolerance when
7363 determining if a pixel line must be processed. It must be an integer
7364 in the range [0,255] and defaults to 10. A value of 0 will result in
7365 applying the process on every pixels.
7368 Paint pixels exceeding the threshold value to white if set to 1.
7372 Set the fields order. Swap fields if set to 1, leave fields alone if
7376 Enable additional sharpening if set to 1. Default is 0.
7379 Enable twoway sharpening if set to 1. Default is 0.
7382 @subsection Examples
7386 Apply default values:
7388 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
7392 Enable additional sharpening:
7398 Paint processed pixels in white:
7404 @section lenscorrection
7406 Correct radial lens distortion
7408 This filter can be used to correct for radial distortion as can result from the use
7409 of wide angle lenses, and thereby re-rectify the image. To find the right parameters
7410 one can use tools available for example as part of opencv or simply trial-and-error.
7411 To use opencv use the calibration sample (under samples/cpp) from the opencv sources
7412 and extract the k1 and k2 coefficients from the resulting matrix.
7414 Note that effectively the same filter is available in the open-source tools Krita and
7415 Digikam from the KDE project.
7417 In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
7418 this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
7419 brightness distribution, so you may want to use both filters together in certain
7420 cases, though you will have to take care of ordering, i.e. whether vignetting should
7421 be applied before or after lens correction.
7425 The filter accepts the following options:
7429 Relative x-coordinate of the focal point of the image, and thereby the center of the
7430 distortion. This value has a range [0,1] and is expressed as fractions of the image
7433 Relative y-coordinate of the focal point of the image, and thereby the center of the
7434 distortion. This value has a range [0,1] and is expressed as fractions of the image
7437 Coefficient of the quadratic correction term. 0.5 means no correction.
7439 Coefficient of the double quadratic correction term. 0.5 means no correction.
7442 The formula that generates the correction is:
7444 @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)
7446 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
7447 distances from the focal point in the source and target images, respectively.
7452 Apply a 3D LUT to an input video.
7454 The filter accepts the following options:
7458 Set the 3D LUT file name.
7460 Currently supported formats:
7472 Select interpolation mode.
7474 Available values are:
7478 Use values from the nearest defined point.
7480 Interpolate values using the 8 points defining a cube.
7482 Interpolate values using a tetrahedron.
7486 @section lut, lutrgb, lutyuv
7488 Compute a look-up table for binding each pixel component input value
7489 to an output value, and apply it to the input video.
7491 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
7492 to an RGB input video.
7494 These filters accept the following parameters:
7497 set first pixel component expression
7499 set second pixel component expression
7501 set third pixel component expression
7503 set fourth pixel component expression, corresponds to the alpha component
7506 set red component expression
7508 set green component expression
7510 set blue component expression
7512 alpha component expression
7515 set Y/luminance component expression
7517 set U/Cb component expression
7519 set V/Cr component expression
7522 Each of them specifies the expression to use for computing the lookup table for
7523 the corresponding pixel component values.
7525 The exact component associated to each of the @var{c*} options depends on the
7528 The @var{lut} filter requires either YUV or RGB pixel formats in input,
7529 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
7531 The expressions can contain the following constants and functions:
7536 The input width and height.
7539 The input value for the pixel component.
7542 The input value, clipped to the @var{minval}-@var{maxval} range.
7545 The maximum value for the pixel component.
7548 The minimum value for the pixel component.
7551 The negated value for the pixel component value, clipped to the
7552 @var{minval}-@var{maxval} range; it corresponds to the expression
7553 "maxval-clipval+minval".
7556 The computed value in @var{val}, clipped to the
7557 @var{minval}-@var{maxval} range.
7559 @item gammaval(gamma)
7560 The computed gamma correction value of the pixel component value,
7561 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
7563 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
7567 All expressions default to "val".
7569 @subsection Examples
7575 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
7576 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
7579 The above is the same as:
7581 lutrgb="r=negval:g=negval:b=negval"
7582 lutyuv="y=negval:u=negval:v=negval"
7592 Remove chroma components, turning the video into a graytone image:
7594 lutyuv="u=128:v=128"
7598 Apply a luma burning effect:
7604 Remove green and blue components:
7610 Set a constant alpha channel value on input:
7612 format=rgba,lutrgb=a="maxval-minval/2"
7616 Correct luminance gamma by a factor of 0.5:
7618 lutyuv=y=gammaval(0.5)
7622 Discard least significant bits of luma:
7624 lutyuv=y='bitand(val, 128+64+32)'
7628 @section maskedmerge
7630 Merge the first input stream with the second input stream using per pixel
7631 weights in the third input stream.
7633 A value of 0 in the third stream pixel component means that pixel component
7634 from first stream is returned unchanged, while maximum value (eg. 255 for
7635 8-bit videos) means that pixel component from second stream is returned
7636 unchanged. Intermediate values define the amount of merging between both
7637 input stream's pixel components.
7639 This filter accepts the following options:
7642 Set which planes will be processed as bitmap, unprocessed planes will be
7643 copied from first stream.
7644 By default value 0xf, all planes will be processed.
7649 Apply motion-compensation deinterlacing.
7651 It needs one field per frame as input and must thus be used together
7652 with yadif=1/3 or equivalent.
7654 This filter accepts the following options:
7657 Set the deinterlacing mode.
7659 It accepts one of the following values:
7664 use iterative motion estimation
7666 like @samp{slow}, but use multiple reference frames.
7668 Default value is @samp{fast}.
7671 Set the picture field parity assumed for the input video. It must be
7672 one of the following values:
7676 assume top field first
7678 assume bottom field first
7681 Default value is @samp{bff}.
7684 Set per-block quantization parameter (QP) used by the internal
7687 Higher values should result in a smoother motion vector field but less
7688 optimal individual vectors. Default value is 1.
7691 @section mergeplanes
7693 Merge color channel components from several video streams.
7695 The filter accepts up to 4 input streams, and merge selected input
7696 planes to the output video.
7698 This filter accepts the following options:
7701 Set input to output plane mapping. Default is @code{0}.
7703 The mappings is specified as a bitmap. It should be specified as a
7704 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
7705 mapping for the first plane of the output stream. 'A' sets the number of
7706 the input stream to use (from 0 to 3), and 'a' the plane number of the
7707 corresponding input to use (from 0 to 3). The rest of the mappings is
7708 similar, 'Bb' describes the mapping for the output stream second
7709 plane, 'Cc' describes the mapping for the output stream third plane and
7710 'Dd' describes the mapping for the output stream fourth plane.
7713 Set output pixel format. Default is @code{yuva444p}.
7716 @subsection Examples
7720 Merge three gray video streams of same width and height into single video stream:
7722 [a0][a1][a2]mergeplanes=0x001020:yuv444p
7726 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
7728 [a0][a1]mergeplanes=0x00010210:yuva444p
7732 Swap Y and A plane in yuva444p stream:
7734 format=yuva444p,mergeplanes=0x03010200:yuva444p
7738 Swap U and V plane in yuv420p stream:
7740 format=yuv420p,mergeplanes=0x000201:yuv420p
7744 Cast a rgb24 clip to yuv444p:
7746 format=rgb24,mergeplanes=0x000102:yuv444p
7752 Drop frames that do not differ greatly from the previous frame in
7753 order to reduce frame rate.
7755 The main use of this filter is for very-low-bitrate encoding
7756 (e.g. streaming over dialup modem), but it could in theory be used for
7757 fixing movies that were inverse-telecined incorrectly.
7759 A description of the accepted options follows.
7763 Set the maximum number of consecutive frames which can be dropped (if
7764 positive), or the minimum interval between dropped frames (if
7765 negative). If the value is 0, the frame is dropped unregarding the
7766 number of previous sequentially dropped frames.
7773 Set the dropping threshold values.
7775 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
7776 represent actual pixel value differences, so a threshold of 64
7777 corresponds to 1 unit of difference for each pixel, or the same spread
7778 out differently over the block.
7780 A frame is a candidate for dropping if no 8x8 blocks differ by more
7781 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
7782 meaning the whole image) differ by more than a threshold of @option{lo}.
7784 Default value for @option{hi} is 64*12, default value for @option{lo} is
7785 64*5, and default value for @option{frac} is 0.33.
7793 It accepts an integer in input; if non-zero it negates the
7794 alpha component (if available). The default value in input is 0.
7798 Force libavfilter not to use any of the specified pixel formats for the
7799 input to the next filter.
7801 It accepts the following parameters:
7805 A '|'-separated list of pixel format names, such as
7806 apix_fmts=yuv420p|monow|rgb24".
7810 @subsection Examples
7814 Force libavfilter to use a format different from @var{yuv420p} for the
7815 input to the vflip filter:
7817 noformat=pix_fmts=yuv420p,vflip
7821 Convert the input video to any of the formats not contained in the list:
7823 noformat=yuv420p|yuv444p|yuv410p
7829 Add noise on video input frame.
7831 The filter accepts the following options:
7839 Set noise seed for specific pixel component or all pixel components in case
7840 of @var{all_seed}. Default value is @code{123457}.
7842 @item all_strength, alls
7843 @item c0_strength, c0s
7844 @item c1_strength, c1s
7845 @item c2_strength, c2s
7846 @item c3_strength, c3s
7847 Set noise strength for specific pixel component or all pixel components in case
7848 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
7850 @item all_flags, allf
7855 Set pixel component flags or set flags for all components if @var{all_flags}.
7856 Available values for component flags are:
7859 averaged temporal noise (smoother)
7861 mix random noise with a (semi)regular pattern
7863 temporal noise (noise pattern changes between frames)
7865 uniform noise (gaussian otherwise)
7869 @subsection Examples
7871 Add temporal and uniform noise to input video:
7873 noise=alls=20:allf=t+u
7878 Pass the video source unchanged to the output.
7881 Optical Character Recognition
7883 This filter uses Tesseract for optical character recognition.
7885 It accepts the following options:
7889 Set datapath to tesseract data. Default is to use whatever was
7890 set at installation.
7893 Set language, default is "eng".
7896 Set character whitelist.
7899 Set character blacklist.
7902 The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
7906 Apply a video transform using libopencv.
7908 To enable this filter, install the libopencv library and headers and
7909 configure FFmpeg with @code{--enable-libopencv}.
7911 It accepts the following parameters:
7916 The name of the libopencv filter to apply.
7919 The parameters to pass to the libopencv filter. If not specified, the default
7924 Refer to the official libopencv documentation for more precise
7926 @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html}
7928 Several libopencv filters are supported; see the following subsections.
7933 Dilate an image by using a specific structuring element.
7934 It corresponds to the libopencv function @code{cvDilate}.
7936 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
7938 @var{struct_el} represents a structuring element, and has the syntax:
7939 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
7941 @var{cols} and @var{rows} represent the number of columns and rows of
7942 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
7943 point, and @var{shape} the shape for the structuring element. @var{shape}
7944 must be "rect", "cross", "ellipse", or "custom".
7946 If the value for @var{shape} is "custom", it must be followed by a
7947 string of the form "=@var{filename}". The file with name
7948 @var{filename} is assumed to represent a binary image, with each
7949 printable character corresponding to a bright pixel. When a custom
7950 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
7951 or columns and rows of the read file are assumed instead.
7953 The default value for @var{struct_el} is "3x3+0x0/rect".
7955 @var{nb_iterations} specifies the number of times the transform is
7956 applied to the image, and defaults to 1.
7960 # Use the default values
7963 # Dilate using a structuring element with a 5x5 cross, iterating two times
7964 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
7966 # Read the shape from the file diamond.shape, iterating two times.
7967 # The file diamond.shape may contain a pattern of characters like this
7973 # The specified columns and rows are ignored
7974 # but the anchor point coordinates are not
7975 ocv=dilate:0x0+2x2/custom=diamond.shape|2
7980 Erode an image by using a specific structuring element.
7981 It corresponds to the libopencv function @code{cvErode}.
7983 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
7984 with the same syntax and semantics as the @ref{dilate} filter.
7988 Smooth the input video.
7990 The filter takes the following parameters:
7991 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
7993 @var{type} is the type of smooth filter to apply, and must be one of
7994 the following values: "blur", "blur_no_scale", "median", "gaussian",
7995 or "bilateral". The default value is "gaussian".
7997 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
7998 depend on the smooth type. @var{param1} and
7999 @var{param2} accept integer positive values or 0. @var{param3} and
8000 @var{param4} accept floating point values.
8002 The default value for @var{param1} is 3. The default value for the
8003 other parameters is 0.
8005 These parameters correspond to the parameters assigned to the
8006 libopencv function @code{cvSmooth}.
8011 Overlay one video on top of another.
8013 It takes two inputs and has one output. The first input is the "main"
8014 video on which the second input is overlaid.
8016 It accepts the following parameters:
8018 A description of the accepted options follows.
8023 Set the expression for the x and y coordinates of the overlaid video
8024 on the main video. Default value is "0" for both expressions. In case
8025 the expression is invalid, it is set to a huge value (meaning that the
8026 overlay will not be displayed within the output visible area).
8029 The action to take when EOF is encountered on the secondary input; it accepts
8030 one of the following values:
8034 Repeat the last frame (the default).
8038 Pass the main input through.
8042 Set when the expressions for @option{x}, and @option{y} are evaluated.
8044 It accepts the following values:
8047 only evaluate expressions once during the filter initialization or
8048 when a command is processed
8051 evaluate expressions for each incoming frame
8054 Default value is @samp{frame}.
8057 If set to 1, force the output to terminate when the shortest input
8058 terminates. Default value is 0.
8061 Set the format for the output video.
8063 It accepts the following values:
8078 Default value is @samp{yuv420}.
8080 @item rgb @emph{(deprecated)}
8081 If set to 1, force the filter to accept inputs in the RGB
8082 color space. Default value is 0. This option is deprecated, use
8083 @option{format} instead.
8086 If set to 1, force the filter to draw the last overlay frame over the
8087 main input until the end of the stream. A value of 0 disables this
8088 behavior. Default value is 1.
8091 The @option{x}, and @option{y} expressions can contain the following
8097 The main input width and height.
8101 The overlay input width and height.
8105 The computed values for @var{x} and @var{y}. They are evaluated for
8110 horizontal and vertical chroma subsample values of the output
8111 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
8115 the number of input frame, starting from 0
8118 the position in the file of the input frame, NAN if unknown
8121 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
8125 Note that the @var{n}, @var{pos}, @var{t} variables are available only
8126 when evaluation is done @emph{per frame}, and will evaluate to NAN
8127 when @option{eval} is set to @samp{init}.
8129 Be aware that frames are taken from each input video in timestamp
8130 order, hence, if their initial timestamps differ, it is a good idea
8131 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
8132 have them begin in the same zero timestamp, as the example for
8133 the @var{movie} filter does.
8135 You can chain together more overlays but you should test the
8136 efficiency of such approach.
8138 @subsection Commands
8140 This filter supports the following commands:
8144 Modify the x and y of the overlay input.
8145 The command accepts the same syntax of the corresponding option.
8147 If the specified expression is not valid, it is kept at its current
8151 @subsection Examples
8155 Draw the overlay at 10 pixels from the bottom right corner of the main
8158 overlay=main_w-overlay_w-10:main_h-overlay_h-10
8161 Using named options the example above becomes:
8163 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
8167 Insert a transparent PNG logo in the bottom left corner of the input,
8168 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
8170 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
8174 Insert 2 different transparent PNG logos (second logo on bottom
8175 right corner) using the @command{ffmpeg} tool:
8177 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
8181 Add a transparent color layer on top of the main video; @code{WxH}
8182 must specify the size of the main input to the overlay filter:
8184 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
8188 Play an original video and a filtered version (here with the deshake
8189 filter) side by side using the @command{ffplay} tool:
8191 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
8194 The above command is the same as:
8196 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
8200 Make a sliding overlay appearing from the left to the right top part of the
8201 screen starting since time 2:
8203 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
8207 Compose output by putting two input videos side to side:
8209 ffmpeg -i left.avi -i right.avi -filter_complex "
8210 nullsrc=size=200x100 [background];
8211 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
8212 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
8213 [background][left] overlay=shortest=1 [background+left];
8214 [background+left][right] overlay=shortest=1:x=100 [left+right]
8219 Mask 10-20 seconds of a video by applying the delogo filter to a section
8221 ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
8222 -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]'
8227 Chain several overlays in cascade:
8229 nullsrc=s=200x200 [bg];
8230 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
8231 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
8232 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
8233 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
8234 [in3] null, [mid2] overlay=100:100 [out0]
8241 Apply Overcomplete Wavelet denoiser.
8243 The filter accepts the following options:
8249 Larger depth values will denoise lower frequency components more, but
8250 slow down filtering.
8252 Must be an int in the range 8-16, default is @code{8}.
8254 @item luma_strength, ls
8257 Must be a double value in the range 0-1000, default is @code{1.0}.
8259 @item chroma_strength, cs
8260 Set chroma strength.
8262 Must be a double value in the range 0-1000, default is @code{1.0}.
8268 Add paddings to the input image, and place the original input at the
8269 provided @var{x}, @var{y} coordinates.
8271 It accepts the following parameters:
8276 Specify an expression for the size of the output image with the
8277 paddings added. If the value for @var{width} or @var{height} is 0, the
8278 corresponding input size is used for the output.
8280 The @var{width} expression can reference the value set by the
8281 @var{height} expression, and vice versa.
8283 The default value of @var{width} and @var{height} is 0.
8287 Specify the offsets to place the input image at within the padded area,
8288 with respect to the top/left border of the output image.
8290 The @var{x} expression can reference the value set by the @var{y}
8291 expression, and vice versa.
8293 The default value of @var{x} and @var{y} is 0.
8296 Specify the color of the padded area. For the syntax of this option,
8297 check the "Color" section in the ffmpeg-utils manual.
8299 The default value of @var{color} is "black".
8302 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
8303 options are expressions containing the following constants:
8308 The input video width and height.
8312 These are the same as @var{in_w} and @var{in_h}.
8316 The output width and height (the size of the padded area), as
8317 specified by the @var{width} and @var{height} expressions.
8321 These are the same as @var{out_w} and @var{out_h}.
8325 The x and y offsets as specified by the @var{x} and @var{y}
8326 expressions, or NAN if not yet specified.
8329 same as @var{iw} / @var{ih}
8332 input sample aspect ratio
8335 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
8339 The horizontal and vertical chroma subsample values. For example for the
8340 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
8343 @subsection Examples
8347 Add paddings with the color "violet" to the input video. The output video
8348 size is 640x480, and the top-left corner of the input video is placed at
8351 pad=640:480:0:40:violet
8354 The example above is equivalent to the following command:
8356 pad=width=640:height=480:x=0:y=40:color=violet
8360 Pad the input to get an output with dimensions increased by 3/2,
8361 and put the input video at the center of the padded area:
8363 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
8367 Pad the input to get a squared output with size equal to the maximum
8368 value between the input width and height, and put the input video at
8369 the center of the padded area:
8371 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
8375 Pad the input to get a final w/h ratio of 16:9:
8377 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
8381 In case of anamorphic video, in order to set the output display aspect
8382 correctly, it is necessary to use @var{sar} in the expression,
8383 according to the relation:
8385 (ih * X / ih) * sar = output_dar
8386 X = output_dar / sar
8389 Thus the previous example needs to be modified to:
8391 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
8395 Double the output size and put the input video in the bottom-right
8396 corner of the output padded area:
8398 pad="2*iw:2*ih:ow-iw:oh-ih"
8405 Generate one palette for a whole video stream.
8407 It accepts the following options:
8411 Set the maximum number of colors to quantize in the palette.
8412 Note: the palette will still contain 256 colors; the unused palette entries
8415 @item reserve_transparent
8416 Create a palette of 255 colors maximum and reserve the last one for
8417 transparency. Reserving the transparency color is useful for GIF optimization.
8418 If not set, the maximum of colors in the palette will be 256. You probably want
8419 to disable this option for a standalone image.
8423 Set statistics mode.
8425 It accepts the following values:
8428 Compute full frame histograms.
8430 Compute histograms only for the part that differs from previous frame. This
8431 might be relevant to give more importance to the moving part of your input if
8432 the background is static.
8435 Default value is @var{full}.
8438 The filter also exports the frame metadata @code{lavfi.color_quant_ratio}
8439 (@code{nb_color_in / nb_color_out}) which you can use to evaluate the degree of
8440 color quantization of the palette. This information is also visible at
8441 @var{info} logging level.
8443 @subsection Examples
8447 Generate a representative palette of a given video using @command{ffmpeg}:
8449 ffmpeg -i input.mkv -vf palettegen palette.png
8455 Use a palette to downsample an input video stream.
8457 The filter takes two inputs: one video stream and a palette. The palette must
8458 be a 256 pixels image.
8460 It accepts the following options:
8464 Select dithering mode. Available algorithms are:
8467 Ordered 8x8 bayer dithering (deterministic)
8469 Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
8470 Note: this dithering is sometimes considered "wrong" and is included as a
8472 @item floyd_steinberg
8473 Floyd and Steingberg dithering (error diffusion)
8475 Frankie Sierra dithering v2 (error diffusion)
8477 Frankie Sierra dithering v2 "Lite" (error diffusion)
8480 Default is @var{sierra2_4a}.
8483 When @var{bayer} dithering is selected, this option defines the scale of the
8484 pattern (how much the crosshatch pattern is visible). A low value means more
8485 visible pattern for less banding, and higher value means less visible pattern
8486 at the cost of more banding.
8488 The option must be an integer value in the range [0,5]. Default is @var{2}.
8491 If set, define the zone to process
8495 Only the changing rectangle will be reprocessed. This is similar to GIF
8496 cropping/offsetting compression mechanism. This option can be useful for speed
8497 if only a part of the image is changing, and has use cases such as limiting the
8498 scope of the error diffusal @option{dither} to the rectangle that bounds the
8499 moving scene (it leads to more deterministic output if the scene doesn't change
8500 much, and as a result less moving noise and better GIF compression).
8503 Default is @var{none}.
8506 @subsection Examples
8510 Use a palette (generated for example with @ref{palettegen}) to encode a GIF
8511 using @command{ffmpeg}:
8513 ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
8517 @section perspective
8519 Correct perspective of video not recorded perpendicular to the screen.
8521 A description of the accepted parameters follows.
8532 Set coordinates expression for top left, top right, bottom left and bottom right corners.
8533 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
8534 If the @code{sense} option is set to @code{source}, then the specified points will be sent
8535 to the corners of the destination. If the @code{sense} option is set to @code{destination},
8536 then the corners of the source will be sent to the specified coordinates.
8538 The expressions can use the following variables:
8543 the width and height of video frame.
8547 Set interpolation for perspective correction.
8549 It accepts the following values:
8555 Default value is @samp{linear}.
8558 Set interpretation of coordinate options.
8560 It accepts the following values:
8564 Send point in the source specified by the given coordinates to
8565 the corners of the destination.
8567 @item 1, destination
8569 Send the corners of the source to the point in the destination specified
8570 by the given coordinates.
8572 Default value is @samp{source}.
8578 Delay interlaced video by one field time so that the field order changes.
8580 The intended use is to fix PAL movies that have been captured with the
8581 opposite field order to the film-to-video transfer.
8583 A description of the accepted parameters follows.
8589 It accepts the following values:
8592 Capture field order top-first, transfer bottom-first.
8593 Filter will delay the bottom field.
8596 Capture field order bottom-first, transfer top-first.
8597 Filter will delay the top field.
8600 Capture and transfer with the same field order. This mode only exists
8601 for the documentation of the other options to refer to, but if you
8602 actually select it, the filter will faithfully do nothing.
8605 Capture field order determined automatically by field flags, transfer
8607 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
8608 basis using field flags. If no field information is available,
8609 then this works just like @samp{u}.
8612 Capture unknown or varying, transfer opposite.
8613 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
8614 analyzing the images and selecting the alternative that produces best
8615 match between the fields.
8618 Capture top-first, transfer unknown or varying.
8619 Filter selects among @samp{t} and @samp{p} using image analysis.
8622 Capture bottom-first, transfer unknown or varying.
8623 Filter selects among @samp{b} and @samp{p} using image analysis.
8626 Capture determined by field flags, transfer unknown or varying.
8627 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
8628 image analysis. If no field information is available, then this works just
8629 like @samp{U}. This is the default mode.
8632 Both capture and transfer unknown or varying.
8633 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
8637 @section pixdesctest
8639 Pixel format descriptor test filter, mainly useful for internal
8640 testing. The output video should be equal to the input video.
8644 format=monow, pixdesctest
8647 can be used to test the monowhite pixel format descriptor definition.
8651 Enable the specified chain of postprocessing subfilters using libpostproc. This
8652 library should be automatically selected with a GPL build (@code{--enable-gpl}).
8653 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
8654 Each subfilter and some options have a short and a long name that can be used
8655 interchangeably, i.e. dr/dering are the same.
8657 The filters accept the following options:
8661 Set postprocessing subfilters string.
8664 All subfilters share common options to determine their scope:
8668 Honor the quality commands for this subfilter.
8671 Do chrominance filtering, too (default).
8674 Do luminance filtering only (no chrominance).
8677 Do chrominance filtering only (no luminance).
8680 These options can be appended after the subfilter name, separated by a '|'.
8682 Available subfilters are:
8685 @item hb/hdeblock[|difference[|flatness]]
8686 Horizontal deblocking filter
8689 Difference factor where higher values mean more deblocking (default: @code{32}).
8691 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8694 @item vb/vdeblock[|difference[|flatness]]
8695 Vertical deblocking filter
8698 Difference factor where higher values mean more deblocking (default: @code{32}).
8700 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8703 @item ha/hadeblock[|difference[|flatness]]
8704 Accurate horizontal deblocking filter
8707 Difference factor where higher values mean more deblocking (default: @code{32}).
8709 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8712 @item va/vadeblock[|difference[|flatness]]
8713 Accurate vertical deblocking filter
8716 Difference factor where higher values mean more deblocking (default: @code{32}).
8718 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8722 The horizontal and vertical deblocking filters share the difference and
8723 flatness values so you cannot set different horizontal and vertical
8728 Experimental horizontal deblocking filter
8731 Experimental vertical deblocking filter
8736 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
8739 larger -> stronger filtering
8741 larger -> stronger filtering
8743 larger -> stronger filtering
8746 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
8749 Stretch luminance to @code{0-255}.
8752 @item lb/linblenddeint
8753 Linear blend deinterlacing filter that deinterlaces the given block by
8754 filtering all lines with a @code{(1 2 1)} filter.
8756 @item li/linipoldeint
8757 Linear interpolating deinterlacing filter that deinterlaces the given block by
8758 linearly interpolating every second line.
8760 @item ci/cubicipoldeint
8761 Cubic interpolating deinterlacing filter deinterlaces the given block by
8762 cubically interpolating every second line.
8764 @item md/mediandeint
8765 Median deinterlacing filter that deinterlaces the given block by applying a
8766 median filter to every second line.
8768 @item fd/ffmpegdeint
8769 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
8770 second line with a @code{(-1 4 2 4 -1)} filter.
8773 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
8774 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
8776 @item fq/forceQuant[|quantizer]
8777 Overrides the quantizer table from the input with the constant quantizer you
8785 Default pp filter combination (@code{hb|a,vb|a,dr|a})
8788 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
8791 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
8794 @subsection Examples
8798 Apply horizontal and vertical deblocking, deringing and automatic
8799 brightness/contrast:
8805 Apply default filters without brightness/contrast correction:
8811 Apply default filters and temporal denoiser:
8813 pp=default/tmpnoise|1|2|3
8817 Apply deblocking on luminance only, and switch vertical deblocking on or off
8818 automatically depending on available CPU time:
8825 Apply Postprocessing filter 7. It is variant of the @ref{spp} filter,
8826 similar to spp = 6 with 7 point DCT, where only the center sample is
8829 The filter accepts the following options:
8833 Force a constant quantization parameter. It accepts an integer in range
8834 0 to 63. If not set, the filter will use the QP from the video stream
8838 Set thresholding mode. Available modes are:
8842 Set hard thresholding.
8844 Set soft thresholding (better de-ringing effect, but likely blurrier).
8846 Set medium thresholding (good results, default).
8852 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
8853 Ratio) between two input videos.
8855 This filter takes in input two input videos, the first input is
8856 considered the "main" source and is passed unchanged to the
8857 output. The second input is used as a "reference" video for computing
8860 Both video inputs must have the same resolution and pixel format for
8861 this filter to work correctly. Also it assumes that both inputs
8862 have the same number of frames, which are compared one by one.
8864 The obtained average PSNR is printed through the logging system.
8866 The filter stores the accumulated MSE (mean squared error) of each
8867 frame, and at the end of the processing it is averaged across all frames
8868 equally, and the following formula is applied to obtain the PSNR:
8871 PSNR = 10*log10(MAX^2/MSE)
8874 Where MAX is the average of the maximum values of each component of the
8877 The description of the accepted parameters follows.
8881 If specified the filter will use the named file to save the PSNR of
8882 each individual frame.
8885 The file printed if @var{stats_file} is selected, contains a sequence of
8886 key/value pairs of the form @var{key}:@var{value} for each compared
8889 A description of each shown parameter follows:
8893 sequential number of the input frame, starting from 1
8896 Mean Square Error pixel-by-pixel average difference of the compared
8897 frames, averaged over all the image components.
8899 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
8900 Mean Square Error pixel-by-pixel average difference of the compared
8901 frames for the component specified by the suffix.
8903 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
8904 Peak Signal to Noise ratio of the compared frames for the component
8905 specified by the suffix.
8910 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
8911 [main][ref] psnr="stats_file=stats.log" [out]
8914 On this example the input file being processed is compared with the
8915 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
8916 is stored in @file{stats.log}.
8921 Pulldown reversal (inverse telecine) filter, capable of handling mixed
8922 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
8925 The pullup filter is designed to take advantage of future context in making
8926 its decisions. This filter is stateless in the sense that it does not lock
8927 onto a pattern to follow, but it instead looks forward to the following
8928 fields in order to identify matches and rebuild progressive frames.
8930 To produce content with an even framerate, insert the fps filter after
8931 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
8932 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
8934 The filter accepts the following options:
8941 These options set the amount of "junk" to ignore at the left, right, top, and
8942 bottom of the image, respectively. Left and right are in units of 8 pixels,
8943 while top and bottom are in units of 2 lines.
8944 The default is 8 pixels on each side.
8947 Set the strict breaks. Setting this option to 1 will reduce the chances of
8948 filter generating an occasional mismatched frame, but it may also cause an
8949 excessive number of frames to be dropped during high motion sequences.
8950 Conversely, setting it to -1 will make filter match fields more easily.
8951 This may help processing of video where there is slight blurring between
8952 the fields, but may also cause there to be interlaced frames in the output.
8953 Default value is @code{0}.
8956 Set the metric plane to use. It accepts the following values:
8962 Use chroma blue plane.
8965 Use chroma red plane.
8968 This option may be set to use chroma plane instead of the default luma plane
8969 for doing filter's computations. This may improve accuracy on very clean
8970 source material, but more likely will decrease accuracy, especially if there
8971 is chroma noise (rainbow effect) or any grayscale video.
8972 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
8973 load and make pullup usable in realtime on slow machines.
8976 For best results (without duplicated frames in the output file) it is
8977 necessary to change the output frame rate. For example, to inverse
8978 telecine NTSC input:
8980 ffmpeg -i input -vf pullup -r 24000/1001 ...
8985 Change video quantization parameters (QP).
8987 The filter accepts the following option:
8991 Set expression for quantization parameter.
8994 The expression is evaluated through the eval API and can contain, among others,
8995 the following constants:
8999 1 if index is not 129, 0 otherwise.
9002 Sequentional index starting from -129 to 128.
9005 @subsection Examples
9017 Flush video frames from internal cache of frames into a random order.
9018 No frame is discarded.
9019 Inspired by @ref{frei0r} nervous filter.
9023 Set size in number of frames of internal cache, in range from @code{2} to
9024 @code{512}. Default is @code{30}.
9027 Set seed for random number generator, must be an integer included between
9028 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9029 less than @code{0}, the filter will try to use a good random seed on a
9033 @section removegrain
9035 The removegrain filter is a spatial denoiser for progressive video.
9039 Set mode for the first plane.
9042 Set mode for the second plane.
9045 Set mode for the third plane.
9048 Set mode for the fourth plane.
9051 Range of mode is from 0 to 24. Description of each mode follows:
9055 Leave input plane unchanged. Default.
9058 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
9061 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
9064 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
9067 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
9068 This is equivalent to a median filter.
9071 Line-sensitive clipping giving the minimal change.
9074 Line-sensitive clipping, intermediate.
9077 Line-sensitive clipping, intermediate.
9080 Line-sensitive clipping, intermediate.
9083 Line-sensitive clipping on a line where the neighbours pixels are the closest.
9086 Replaces the target pixel with the closest neighbour.
9089 [1 2 1] horizontal and vertical kernel blur.
9095 Bob mode, interpolates top field from the line where the neighbours
9096 pixels are the closest.
9099 Bob mode, interpolates bottom field from the line where the neighbours
9100 pixels are the closest.
9103 Bob mode, interpolates top field. Same as 13 but with a more complicated
9104 interpolation formula.
9107 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
9108 interpolation formula.
9111 Clips the pixel with the minimum and maximum of respectively the maximum and
9112 minimum of each pair of opposite neighbour pixels.
9115 Line-sensitive clipping using opposite neighbours whose greatest distance from
9116 the current pixel is minimal.
9119 Replaces the pixel with the average of its 8 neighbours.
9122 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
9125 Clips pixels using the averages of opposite neighbour.
9128 Same as mode 21 but simpler and faster.
9131 Small edge and halo removal, but reputed useless.
9139 Suppress a TV station logo, using an image file to determine which
9140 pixels comprise the logo. It works by filling in the pixels that
9141 comprise the logo with neighboring pixels.
9143 The filter accepts the following options:
9147 Set the filter bitmap file, which can be any image format supported by
9148 libavformat. The width and height of the image file must match those of the
9149 video stream being processed.
9152 Pixels in the provided bitmap image with a value of zero are not
9153 considered part of the logo, non-zero pixels are considered part of
9154 the logo. If you use white (255) for the logo and black (0) for the
9155 rest, you will be safe. For making the filter bitmap, it is
9156 recommended to take a screen capture of a black frame with the logo
9157 visible, and then using a threshold filter followed by the erode
9158 filter once or twice.
9160 If needed, little splotches can be fixed manually. Remember that if
9161 logo pixels are not covered, the filter quality will be much
9162 reduced. Marking too many pixels as part of the logo does not hurt as
9163 much, but it will increase the amount of blurring needed to cover over
9164 the image and will destroy more information than necessary, and extra
9165 pixels will slow things down on a large logo.
9167 @section repeatfields
9169 This filter uses the repeat_field flag from the Video ES headers and hard repeats
9170 fields based on its value.
9172 @section reverse, areverse
9176 Warning: This filter requires memory to buffer the entire clip, so trimming
9179 @subsection Examples
9183 Take the first 5 seconds of a clip, and reverse it.
9191 Rotate video by an arbitrary angle expressed in radians.
9193 The filter accepts the following options:
9195 A description of the optional parameters follows.
9198 Set an expression for the angle by which to rotate the input video
9199 clockwise, expressed as a number of radians. A negative value will
9200 result in a counter-clockwise rotation. By default it is set to "0".
9202 This expression is evaluated for each frame.
9205 Set the output width expression, default value is "iw".
9206 This expression is evaluated just once during configuration.
9209 Set the output height expression, default value is "ih".
9210 This expression is evaluated just once during configuration.
9213 Enable bilinear interpolation if set to 1, a value of 0 disables
9214 it. Default value is 1.
9217 Set the color used to fill the output area not covered by the rotated
9218 image. For the general syntax of this option, check the "Color" section in the
9219 ffmpeg-utils manual. If the special value "none" is selected then no
9220 background is printed (useful for example if the background is never shown).
9222 Default value is "black".
9225 The expressions for the angle and the output size can contain the
9226 following constants and functions:
9230 sequential number of the input frame, starting from 0. It is always NAN
9231 before the first frame is filtered.
9234 time in seconds of the input frame, it is set to 0 when the filter is
9235 configured. It is always NAN before the first frame is filtered.
9239 horizontal and vertical chroma subsample values. For example for the
9240 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9244 the input video width and height
9248 the output width and height, that is the size of the padded area as
9249 specified by the @var{width} and @var{height} expressions
9253 the minimal width/height required for completely containing the input
9254 video rotated by @var{a} radians.
9256 These are only available when computing the @option{out_w} and
9257 @option{out_h} expressions.
9260 @subsection Examples
9264 Rotate the input by PI/6 radians clockwise:
9270 Rotate the input by PI/6 radians counter-clockwise:
9276 Rotate the input by 45 degrees clockwise:
9282 Apply a constant rotation with period T, starting from an angle of PI/3:
9284 rotate=PI/3+2*PI*t/T
9288 Make the input video rotation oscillating with a period of T
9289 seconds and an amplitude of A radians:
9291 rotate=A*sin(2*PI/T*t)
9295 Rotate the video, output size is chosen so that the whole rotating
9296 input video is always completely contained in the output:
9298 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
9302 Rotate the video, reduce the output size so that no background is ever
9305 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
9309 @subsection Commands
9311 The filter supports the following commands:
9315 Set the angle expression.
9316 The command accepts the same syntax of the corresponding option.
9318 If the specified expression is not valid, it is kept at its current
9324 Apply Shape Adaptive Blur.
9326 The filter accepts the following options:
9329 @item luma_radius, lr
9330 Set luma blur filter strength, must be a value in range 0.1-4.0, default
9331 value is 1.0. A greater value will result in a more blurred image, and
9332 in slower processing.
9334 @item luma_pre_filter_radius, lpfr
9335 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
9338 @item luma_strength, ls
9339 Set luma maximum difference between pixels to still be considered, must
9340 be a value in the 0.1-100.0 range, default value is 1.0.
9342 @item chroma_radius, cr
9343 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
9344 greater value will result in a more blurred image, and in slower
9347 @item chroma_pre_filter_radius, cpfr
9348 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
9350 @item chroma_strength, cs
9351 Set chroma maximum difference between pixels to still be considered,
9352 must be a value in the 0.1-100.0 range.
9355 Each chroma option value, if not explicitly specified, is set to the
9356 corresponding luma option value.
9361 Scale (resize) the input video, using the libswscale library.
9363 The scale filter forces the output display aspect ratio to be the same
9364 of the input, by changing the output sample aspect ratio.
9366 If the input image format is different from the format requested by
9367 the next filter, the scale filter will convert the input to the
9371 The filter accepts the following options, or any of the options
9372 supported by the libswscale scaler.
9374 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
9375 the complete list of scaler options.
9380 Set the output video dimension expression. Default value is the input
9383 If the value is 0, the input width is used for the output.
9385 If one of the values is -1, the scale filter will use a value that
9386 maintains the aspect ratio of the input image, calculated from the
9387 other specified dimension. If both of them are -1, the input size is
9390 If one of the values is -n with n > 1, the scale filter will also use a value
9391 that maintains the aspect ratio of the input image, calculated from the other
9392 specified dimension. After that it will, however, make sure that the calculated
9393 dimension is divisible by n and adjust the value if necessary.
9395 See below for the list of accepted constants for use in the dimension
9399 Set the interlacing mode. It accepts the following values:
9403 Force interlaced aware scaling.
9406 Do not apply interlaced scaling.
9409 Select interlaced aware scaling depending on whether the source frames
9410 are flagged as interlaced or not.
9413 Default value is @samp{0}.
9416 Set libswscale scaling flags. See
9417 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
9418 complete list of values. If not explicitly specified the filter applies
9422 Set the video size. For the syntax of this option, check the
9423 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9425 @item in_color_matrix
9426 @item out_color_matrix
9427 Set in/output YCbCr color space type.
9429 This allows the autodetected value to be overridden as well as allows forcing
9430 a specific value used for the output and encoder.
9432 If not specified, the color space type depends on the pixel format.
9438 Choose automatically.
9441 Format conforming to International Telecommunication Union (ITU)
9442 Recommendation BT.709.
9445 Set color space conforming to the United States Federal Communications
9446 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
9449 Set color space conforming to:
9453 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
9456 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
9459 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
9464 Set color space conforming to SMPTE ST 240:1999.
9469 Set in/output YCbCr sample range.
9471 This allows the autodetected value to be overridden as well as allows forcing
9472 a specific value used for the output and encoder. If not specified, the
9473 range depends on the pixel format. Possible values:
9477 Choose automatically.
9480 Set full range (0-255 in case of 8-bit luma).
9483 Set "MPEG" range (16-235 in case of 8-bit luma).
9486 @item force_original_aspect_ratio
9487 Enable decreasing or increasing output video width or height if necessary to
9488 keep the original aspect ratio. Possible values:
9492 Scale the video as specified and disable this feature.
9495 The output video dimensions will automatically be decreased if needed.
9498 The output video dimensions will automatically be increased if needed.
9502 One useful instance of this option is that when you know a specific device's
9503 maximum allowed resolution, you can use this to limit the output video to
9504 that, while retaining the aspect ratio. For example, device A allows
9505 1280x720 playback, and your video is 1920x800. Using this option (set it to
9506 decrease) and specifying 1280x720 to the command line makes the output
9509 Please note that this is a different thing than specifying -1 for @option{w}
9510 or @option{h}, you still need to specify the output resolution for this option
9515 The values of the @option{w} and @option{h} options are expressions
9516 containing the following constants:
9521 The input width and height
9525 These are the same as @var{in_w} and @var{in_h}.
9529 The output (scaled) width and height
9533 These are the same as @var{out_w} and @var{out_h}
9536 The same as @var{iw} / @var{ih}
9539 input sample aspect ratio
9542 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
9546 horizontal and vertical input chroma subsample values. For example for the
9547 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9551 horizontal and vertical output chroma subsample values. For example for the
9552 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9555 @subsection Examples
9559 Scale the input video to a size of 200x100
9564 This is equivalent to:
9575 Specify a size abbreviation for the output size:
9580 which can also be written as:
9586 Scale the input to 2x:
9592 The above is the same as:
9598 Scale the input to 2x with forced interlaced scaling:
9600 scale=2*iw:2*ih:interl=1
9604 Scale the input to half size:
9610 Increase the width, and set the height to the same size:
9623 Increase the height, and set the width to 3/2 of the height:
9625 scale=w=3/2*oh:h=3/5*ih
9629 Increase the size, making the size a multiple of the chroma
9632 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
9636 Increase the width to a maximum of 500 pixels,
9637 keeping the same aspect ratio as the input:
9639 scale=w='min(500\, iw*3/2):h=-1'
9643 @subsection Commands
9645 This filter supports the following commands:
9649 Set the output video dimension expression.
9650 The command accepts the same syntax of the corresponding option.
9652 If the specified expression is not valid, it is kept at its current
9658 Scale (resize) the input video, based on a reference video.
9660 See the scale filter for available options, scale2ref supports the same but
9661 uses the reference video instead of the main input as basis.
9663 @subsection Examples
9667 Scale a subtitle stream to match the main video in size before overlaying
9669 'scale2ref[b][a];[a][b]overlay'
9673 @section separatefields
9675 The @code{separatefields} takes a frame-based video input and splits
9676 each frame into its components fields, producing a new half height clip
9677 with twice the frame rate and twice the frame count.
9679 This filter use field-dominance information in frame to decide which
9680 of each pair of fields to place first in the output.
9681 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
9683 @section setdar, setsar
9685 The @code{setdar} filter sets the Display Aspect Ratio for the filter
9688 This is done by changing the specified Sample (aka Pixel) Aspect
9689 Ratio, according to the following equation:
9691 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
9694 Keep in mind that the @code{setdar} filter does not modify the pixel
9695 dimensions of the video frame. Also, the display aspect ratio set by
9696 this filter may be changed by later filters in the filterchain,
9697 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
9700 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
9701 the filter output video.
9703 Note that as a consequence of the application of this filter, the
9704 output display aspect ratio will change according to the equation
9707 Keep in mind that the sample aspect ratio set by the @code{setsar}
9708 filter may be changed by later filters in the filterchain, e.g. if
9709 another "setsar" or a "setdar" filter is applied.
9711 It accepts the following parameters:
9714 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
9715 Set the aspect ratio used by the filter.
9717 The parameter can be a floating point number string, an expression, or
9718 a string of the form @var{num}:@var{den}, where @var{num} and
9719 @var{den} are the numerator and denominator of the aspect ratio. If
9720 the parameter is not specified, it is assumed the value "0".
9721 In case the form "@var{num}:@var{den}" is used, the @code{:} character
9725 Set the maximum integer value to use for expressing numerator and
9726 denominator when reducing the expressed aspect ratio to a rational.
9727 Default value is @code{100}.
9731 The parameter @var{sar} is an expression containing
9732 the following constants:
9736 These are approximated values for the mathematical constants e
9737 (Euler's number), pi (Greek pi), and phi (the golden ratio).
9740 The input width and height.
9743 These are the same as @var{w} / @var{h}.
9746 The input sample aspect ratio.
9749 The input display aspect ratio. It is the same as
9750 (@var{w} / @var{h}) * @var{sar}.
9753 Horizontal and vertical chroma subsample values. For example, for the
9754 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9757 @subsection Examples
9762 To change the display aspect ratio to 16:9, specify one of the following:
9770 To change the sample aspect ratio to 10:11, specify:
9776 To set a display aspect ratio of 16:9, and specify a maximum integer value of
9777 1000 in the aspect ratio reduction, use the command:
9779 setdar=ratio=16/9:max=1000
9787 Force field for the output video frame.
9789 The @code{setfield} filter marks the interlace type field for the
9790 output frames. It does not change the input frame, but only sets the
9791 corresponding property, which affects how the frame is treated by
9792 following filters (e.g. @code{fieldorder} or @code{yadif}).
9794 The filter accepts the following options:
9799 Available values are:
9803 Keep the same field property.
9806 Mark the frame as bottom-field-first.
9809 Mark the frame as top-field-first.
9812 Mark the frame as progressive.
9818 Show a line containing various information for each input video frame.
9819 The input video is not modified.
9821 The shown line contains a sequence of key/value pairs of the form
9822 @var{key}:@var{value}.
9824 The following values are shown in the output:
9828 The (sequential) number of the input frame, starting from 0.
9831 The Presentation TimeStamp of the input frame, expressed as a number of
9832 time base units. The time base unit depends on the filter input pad.
9835 The Presentation TimeStamp of the input frame, expressed as a number of
9839 The position of the frame in the input stream, or -1 if this information is
9840 unavailable and/or meaningless (for example in case of synthetic video).
9843 The pixel format name.
9846 The sample aspect ratio of the input frame, expressed in the form
9847 @var{num}/@var{den}.
9850 The size of the input frame. For the syntax of this option, check the
9851 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9854 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
9855 for bottom field first).
9858 This is 1 if the frame is a key frame, 0 otherwise.
9861 The picture type of the input frame ("I" for an I-frame, "P" for a
9862 P-frame, "B" for a B-frame, or "?" for an unknown type).
9863 Also refer to the documentation of the @code{AVPictureType} enum and of
9864 the @code{av_get_picture_type_char} function defined in
9865 @file{libavutil/avutil.h}.
9868 The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
9870 @item plane_checksum
9871 The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
9872 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]".
9875 @section showpalette
9877 Displays the 256 colors palette of each frame. This filter is only relevant for
9878 @var{pal8} pixel format frames.
9880 It accepts the following option:
9884 Set the size of the box used to represent one palette color entry. Default is
9885 @code{30} (for a @code{30x30} pixel box).
9888 @section shuffleplanes
9890 Reorder and/or duplicate video planes.
9892 It accepts the following parameters:
9897 The index of the input plane to be used as the first output plane.
9900 The index of the input plane to be used as the second output plane.
9903 The index of the input plane to be used as the third output plane.
9906 The index of the input plane to be used as the fourth output plane.
9910 The first plane has the index 0. The default is to keep the input unchanged.
9912 Swap the second and third planes of the input:
9914 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
9917 @anchor{signalstats}
9918 @section signalstats
9919 Evaluate various visual metrics that assist in determining issues associated
9920 with the digitization of analog video media.
9922 By default the filter will log these metadata values:
9926 Display the minimal Y value contained within the input frame. Expressed in
9930 Display the Y value at the 10% percentile within the input frame. Expressed in
9934 Display the average Y value within the input frame. Expressed in range of
9938 Display the Y value at the 90% percentile within the input frame. Expressed in
9942 Display the maximum Y value contained within the input frame. Expressed in
9946 Display the minimal U value contained within the input frame. Expressed in
9950 Display the U value at the 10% percentile within the input frame. Expressed in
9954 Display the average U value within the input frame. Expressed in range of
9958 Display the U value at the 90% percentile within the input frame. Expressed in
9962 Display the maximum U value contained within the input frame. Expressed in
9966 Display the minimal V value contained within the input frame. Expressed in
9970 Display the V value at the 10% percentile within the input frame. Expressed in
9974 Display the average V value within the input frame. Expressed in range of
9978 Display the V value at the 90% percentile within the input frame. Expressed in
9982 Display the maximum V value contained within the input frame. Expressed in
9986 Display the minimal saturation value contained within the input frame.
9987 Expressed in range of [0-~181.02].
9990 Display the saturation value at the 10% percentile within the input frame.
9991 Expressed in range of [0-~181.02].
9994 Display the average saturation value within the input frame. Expressed in range
9998 Display the saturation value at the 90% percentile within the input frame.
9999 Expressed in range of [0-~181.02].
10002 Display the maximum saturation value contained within the input frame.
10003 Expressed in range of [0-~181.02].
10006 Display the median value for hue within the input frame. Expressed in range of
10010 Display the average value for hue within the input frame. Expressed in range of
10014 Display the average of sample value difference between all values of the Y
10015 plane in the current frame and corresponding values of the previous input frame.
10016 Expressed in range of [0-255].
10019 Display the average of sample value difference between all values of the U
10020 plane in the current frame and corresponding values of the previous input frame.
10021 Expressed in range of [0-255].
10024 Display the average of sample value difference between all values of the V
10025 plane in the current frame and corresponding values of the previous input frame.
10026 Expressed in range of [0-255].
10029 The filter accepts the following options:
10035 @option{stat} specify an additional form of image analysis.
10036 @option{out} output video with the specified type of pixel highlighted.
10038 Both options accept the following values:
10042 Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel
10043 unlike the neighboring pixels of the same field. Examples of temporal outliers
10044 include the results of video dropouts, head clogs, or tape tracking issues.
10047 Identify @var{vertical line repetition}. Vertical line repetition includes
10048 similar rows of pixels within a frame. In born-digital video vertical line
10049 repetition is common, but this pattern is uncommon in video digitized from an
10050 analog source. When it occurs in video that results from the digitization of an
10051 analog source it can indicate concealment from a dropout compensator.
10054 Identify pixels that fall outside of legal broadcast range.
10058 Set the highlight color for the @option{out} option. The default color is
10062 @subsection Examples
10066 Output data of various video metrics:
10068 ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
10072 Output specific data about the minimum and maximum values of the Y plane per frame:
10074 ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
10078 Playback video while highlighting pixels that are outside of broadcast range in red.
10080 ffplay example.mov -vf signalstats="out=brng:color=red"
10084 Playback video with signalstats metadata drawn over the frame.
10086 ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
10089 The contents of signalstat_drawtext.txt used in the command are:
10092 Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@})
10093 U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@})
10094 V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@})
10095 saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@}
10103 Blur the input video without impacting the outlines.
10105 It accepts the following options:
10108 @item luma_radius, lr
10109 Set the luma radius. The option value must be a float number in
10110 the range [0.1,5.0] that specifies the variance of the gaussian filter
10111 used to blur the image (slower if larger). Default value is 1.0.
10113 @item luma_strength, ls
10114 Set the luma strength. The option value must be a float number
10115 in the range [-1.0,1.0] that configures the blurring. A value included
10116 in [0.0,1.0] will blur the image whereas a value included in
10117 [-1.0,0.0] will sharpen the image. Default value is 1.0.
10119 @item luma_threshold, lt
10120 Set the luma threshold used as a coefficient to determine
10121 whether a pixel should be blurred or not. The option value must be an
10122 integer in the range [-30,30]. A value of 0 will filter all the image,
10123 a value included in [0,30] will filter flat areas and a value included
10124 in [-30,0] will filter edges. Default value is 0.
10126 @item chroma_radius, cr
10127 Set the chroma radius. The option value must be a float number in
10128 the range [0.1,5.0] that specifies the variance of the gaussian filter
10129 used to blur the image (slower if larger). Default value is 1.0.
10131 @item chroma_strength, cs
10132 Set the chroma strength. The option value must be a float number
10133 in the range [-1.0,1.0] that configures the blurring. A value included
10134 in [0.0,1.0] will blur the image whereas a value included in
10135 [-1.0,0.0] will sharpen the image. Default value is 1.0.
10137 @item chroma_threshold, ct
10138 Set the chroma threshold used as a coefficient to determine
10139 whether a pixel should be blurred or not. The option value must be an
10140 integer in the range [-30,30]. A value of 0 will filter all the image,
10141 a value included in [0,30] will filter flat areas and a value included
10142 in [-30,0] will filter edges. Default value is 0.
10145 If a chroma option is not explicitly set, the corresponding luma value
10150 Obtain the SSIM (Structural SImilarity Metric) between two input videos.
10152 This filter takes in input two input videos, the first input is
10153 considered the "main" source and is passed unchanged to the
10154 output. The second input is used as a "reference" video for computing
10157 Both video inputs must have the same resolution and pixel format for
10158 this filter to work correctly. Also it assumes that both inputs
10159 have the same number of frames, which are compared one by one.
10161 The filter stores the calculated SSIM of each frame.
10163 The description of the accepted parameters follows.
10166 @item stats_file, f
10167 If specified the filter will use the named file to save the SSIM of
10168 each individual frame.
10171 The file printed if @var{stats_file} is selected, contains a sequence of
10172 key/value pairs of the form @var{key}:@var{value} for each compared
10175 A description of each shown parameter follows:
10179 sequential number of the input frame, starting from 1
10181 @item Y, U, V, R, G, B
10182 SSIM of the compared frames for the component specified by the suffix.
10185 SSIM of the compared frames for the whole frame.
10188 Same as above but in dB representation.
10193 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
10194 [main][ref] ssim="stats_file=stats.log" [out]
10197 On this example the input file being processed is compared with the
10198 reference file @file{ref_movie.mpg}. The SSIM of each individual frame
10199 is stored in @file{stats.log}.
10201 Another example with both psnr and ssim at same time:
10203 ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
10208 Convert between different stereoscopic image formats.
10210 The filters accept the following options:
10214 Set stereoscopic image format of input.
10216 Available values for input image formats are:
10219 side by side parallel (left eye left, right eye right)
10222 side by side crosseye (right eye left, left eye right)
10225 side by side parallel with half width resolution
10226 (left eye left, right eye right)
10229 side by side crosseye with half width resolution
10230 (right eye left, left eye right)
10233 above-below (left eye above, right eye below)
10236 above-below (right eye above, left eye below)
10239 above-below with half height resolution
10240 (left eye above, right eye below)
10243 above-below with half height resolution
10244 (right eye above, left eye below)
10247 alternating frames (left eye first, right eye second)
10250 alternating frames (right eye first, left eye second)
10253 interleaved rows (left eye has top row, right eye starts on next row)
10256 interleaved rows (right eye has top row, left eye starts on next row)
10258 Default value is @samp{sbsl}.
10262 Set stereoscopic image format of output.
10264 Available values for output image formats are all the input formats as well as:
10267 anaglyph red/blue gray
10268 (red filter on left eye, blue filter on right eye)
10271 anaglyph red/green gray
10272 (red filter on left eye, green filter on right eye)
10275 anaglyph red/cyan gray
10276 (red filter on left eye, cyan filter on right eye)
10279 anaglyph red/cyan half colored
10280 (red filter on left eye, cyan filter on right eye)
10283 anaglyph red/cyan color
10284 (red filter on left eye, cyan filter on right eye)
10287 anaglyph red/cyan color optimized with the least squares projection of dubois
10288 (red filter on left eye, cyan filter on right eye)
10291 anaglyph green/magenta gray
10292 (green filter on left eye, magenta filter on right eye)
10295 anaglyph green/magenta half colored
10296 (green filter on left eye, magenta filter on right eye)
10299 anaglyph green/magenta colored
10300 (green filter on left eye, magenta filter on right eye)
10303 anaglyph green/magenta color optimized with the least squares projection of dubois
10304 (green filter on left eye, magenta filter on right eye)
10307 anaglyph yellow/blue gray
10308 (yellow filter on left eye, blue filter on right eye)
10311 anaglyph yellow/blue half colored
10312 (yellow filter on left eye, blue filter on right eye)
10315 anaglyph yellow/blue colored
10316 (yellow filter on left eye, blue filter on right eye)
10319 anaglyph yellow/blue color optimized with the least squares projection of dubois
10320 (yellow filter on left eye, blue filter on right eye)
10323 mono output (left eye only)
10326 mono output (right eye only)
10329 checkerboard, left eye first
10332 checkerboard, right eye first
10335 interleaved columns, left eye first
10338 interleaved columns, right eye first
10341 Default value is @samp{arcd}.
10344 @subsection Examples
10348 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
10354 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
10363 Apply a simple postprocessing filter that compresses and decompresses the image
10364 at several (or - in the case of @option{quality} level @code{6} - all) shifts
10365 and average the results.
10367 The filter accepts the following options:
10371 Set quality. This option defines the number of levels for averaging. It accepts
10372 an integer in the range 0-6. If set to @code{0}, the filter will have no
10373 effect. A value of @code{6} means the higher quality. For each increment of
10374 that value the speed drops by a factor of approximately 2. Default value is
10378 Force a constant quantization parameter. If not set, the filter will use the QP
10379 from the video stream (if available).
10382 Set thresholding mode. Available modes are:
10386 Set hard thresholding (default).
10388 Set soft thresholding (better de-ringing effect, but likely blurrier).
10391 @item use_bframe_qp
10392 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
10393 option may cause flicker since the B-Frames have often larger QP. Default is
10394 @code{0} (not enabled).
10400 Draw subtitles on top of input video using the libass library.
10402 To enable compilation of this filter you need to configure FFmpeg with
10403 @code{--enable-libass}. This filter also requires a build with libavcodec and
10404 libavformat to convert the passed subtitles file to ASS (Advanced Substation
10405 Alpha) subtitles format.
10407 The filter accepts the following options:
10411 Set the filename of the subtitle file to read. It must be specified.
10413 @item original_size
10414 Specify the size of the original video, the video for which the ASS file
10415 was composed. For the syntax of this option, check the
10416 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10417 Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
10418 correctly scale the fonts if the aspect ratio has been changed.
10421 Set a directory path containing fonts that can be used by the filter.
10422 These fonts will be used in addition to whatever the font provider uses.
10425 Set subtitles input character encoding. @code{subtitles} filter only. Only
10426 useful if not UTF-8.
10428 @item stream_index, si
10429 Set subtitles stream index. @code{subtitles} filter only.
10432 Override default style or script info parameters of the subtitles. It accepts a
10433 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
10436 If the first key is not specified, it is assumed that the first value
10437 specifies the @option{filename}.
10439 For example, to render the file @file{sub.srt} on top of the input
10440 video, use the command:
10445 which is equivalent to:
10447 subtitles=filename=sub.srt
10450 To render the default subtitles stream from file @file{video.mkv}, use:
10452 subtitles=video.mkv
10455 To render the second subtitles stream from that file, use:
10457 subtitles=video.mkv:si=1
10460 To make the subtitles stream from @file{sub.srt} appear in transparent green
10461 @code{DejaVu Serif}, use:
10463 subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
10466 @section super2xsai
10468 Scale the input by 2x and smooth using the Super2xSaI (Scale and
10469 Interpolate) pixel art scaling algorithm.
10471 Useful for enlarging pixel art images without reducing sharpness.
10478 Apply telecine process to the video.
10480 This filter accepts the following options:
10489 The default value is @code{top}.
10493 A string of numbers representing the pulldown pattern you wish to apply.
10494 The default value is @code{23}.
10498 Some typical patterns:
10503 24p: 2332 (preferred)
10510 24p: 222222222223 ("Euro pulldown")
10516 Select the most representative frame in a given sequence of consecutive frames.
10518 The filter accepts the following options:
10522 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
10523 will pick one of them, and then handle the next batch of @var{n} frames until
10524 the end. Default is @code{100}.
10527 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
10528 value will result in a higher memory usage, so a high value is not recommended.
10530 @subsection Examples
10534 Extract one picture each 50 frames:
10540 Complete example of a thumbnail creation with @command{ffmpeg}:
10542 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
10548 Tile several successive frames together.
10550 The filter accepts the following options:
10555 Set the grid size (i.e. the number of lines and columns). For the syntax of
10556 this option, check the
10557 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10560 Set the maximum number of frames to render in the given area. It must be less
10561 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
10562 the area will be used.
10565 Set the outer border margin in pixels.
10568 Set the inner border thickness (i.e. the number of pixels between frames). For
10569 more advanced padding options (such as having different values for the edges),
10570 refer to the pad video filter.
10573 Specify the color of the unused area. For the syntax of this option, check the
10574 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
10578 @subsection Examples
10582 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
10584 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
10586 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
10587 duplicating each output frame to accommodate the originally detected frame
10591 Display @code{5} pictures in an area of @code{3x2} frames,
10592 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
10593 mixed flat and named options:
10595 tile=3x2:nb_frames=5:padding=7:margin=2
10599 @section tinterlace
10601 Perform various types of temporal field interlacing.
10603 Frames are counted starting from 1, so the first input frame is
10606 The filter accepts the following options:
10611 Specify the mode of the interlacing. This option can also be specified
10612 as a value alone. See below for a list of values for this option.
10614 Available values are:
10618 Move odd frames into the upper field, even into the lower field,
10619 generating a double height frame at half frame rate.
10623 Frame 1 Frame 2 Frame 3 Frame 4
10625 11111 22222 33333 44444
10626 11111 22222 33333 44444
10627 11111 22222 33333 44444
10628 11111 22222 33333 44444
10642 Only output even frames, odd frames are dropped, generating a frame with
10643 unchanged height at half frame rate.
10648 Frame 1 Frame 2 Frame 3 Frame 4
10650 11111 22222 33333 44444
10651 11111 22222 33333 44444
10652 11111 22222 33333 44444
10653 11111 22222 33333 44444
10663 Only output odd frames, even frames are dropped, generating a frame with
10664 unchanged height at half frame rate.
10669 Frame 1 Frame 2 Frame 3 Frame 4
10671 11111 22222 33333 44444
10672 11111 22222 33333 44444
10673 11111 22222 33333 44444
10674 11111 22222 33333 44444
10684 Expand each frame to full height, but pad alternate lines with black,
10685 generating a frame with double height at the same input frame rate.
10690 Frame 1 Frame 2 Frame 3 Frame 4
10692 11111 22222 33333 44444
10693 11111 22222 33333 44444
10694 11111 22222 33333 44444
10695 11111 22222 33333 44444
10698 11111 ..... 33333 .....
10699 ..... 22222 ..... 44444
10700 11111 ..... 33333 .....
10701 ..... 22222 ..... 44444
10702 11111 ..... 33333 .....
10703 ..... 22222 ..... 44444
10704 11111 ..... 33333 .....
10705 ..... 22222 ..... 44444
10709 @item interleave_top, 4
10710 Interleave the upper field from odd frames with the lower field from
10711 even frames, generating a frame with unchanged height at half frame rate.
10716 Frame 1 Frame 2 Frame 3 Frame 4
10718 11111<- 22222 33333<- 44444
10719 11111 22222<- 33333 44444<-
10720 11111<- 22222 33333<- 44444
10721 11111 22222<- 33333 44444<-
10731 @item interleave_bottom, 5
10732 Interleave the lower field from odd frames with the upper field from
10733 even frames, generating a frame with unchanged height at half frame rate.
10738 Frame 1 Frame 2 Frame 3 Frame 4
10740 11111 22222<- 33333 44444<-
10741 11111<- 22222 33333<- 44444
10742 11111 22222<- 33333 44444<-
10743 11111<- 22222 33333<- 44444
10753 @item interlacex2, 6
10754 Double frame rate with unchanged height. Frames are inserted each
10755 containing the second temporal field from the previous input frame and
10756 the first temporal field from the next input frame. This mode relies on
10757 the top_field_first flag. Useful for interlaced video displays with no
10758 field synchronisation.
10763 Frame 1 Frame 2 Frame 3 Frame 4
10765 11111 22222 33333 44444
10766 11111 22222 33333 44444
10767 11111 22222 33333 44444
10768 11111 22222 33333 44444
10771 11111 22222 22222 33333 33333 44444 44444
10772 11111 11111 22222 22222 33333 33333 44444
10773 11111 22222 22222 33333 33333 44444 44444
10774 11111 11111 22222 22222 33333 33333 44444
10780 Numeric values are deprecated but are accepted for backward
10781 compatibility reasons.
10783 Default mode is @code{merge}.
10786 Specify flags influencing the filter process.
10788 Available value for @var{flags} is:
10791 @item low_pass_filter, vlfp
10792 Enable vertical low-pass filtering in the filter.
10793 Vertical low-pass filtering is required when creating an interlaced
10794 destination from a progressive source which contains high-frequency
10795 vertical detail. Filtering will reduce interlace 'twitter' and Moire
10798 Vertical low-pass filtering can only be enabled for @option{mode}
10799 @var{interleave_top} and @var{interleave_bottom}.
10806 Transpose rows with columns in the input video and optionally flip it.
10808 It accepts the following parameters:
10813 Specify the transposition direction.
10815 Can assume the following values:
10817 @item 0, 4, cclock_flip
10818 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
10826 Rotate by 90 degrees clockwise, that is:
10834 Rotate by 90 degrees counterclockwise, that is:
10841 @item 3, 7, clock_flip
10842 Rotate by 90 degrees clockwise and vertically flip, that is:
10850 For values between 4-7, the transposition is only done if the input
10851 video geometry is portrait and not landscape. These values are
10852 deprecated, the @code{passthrough} option should be used instead.
10854 Numerical values are deprecated, and should be dropped in favor of
10855 symbolic constants.
10858 Do not apply the transposition if the input geometry matches the one
10859 specified by the specified value. It accepts the following values:
10862 Always apply transposition.
10864 Preserve portrait geometry (when @var{height} >= @var{width}).
10866 Preserve landscape geometry (when @var{width} >= @var{height}).
10869 Default value is @code{none}.
10872 For example to rotate by 90 degrees clockwise and preserve portrait
10875 transpose=dir=1:passthrough=portrait
10878 The command above can also be specified as:
10880 transpose=1:portrait
10884 Trim the input so that the output contains one continuous subpart of the input.
10886 It accepts the following parameters:
10889 Specify the time of the start of the kept section, i.e. the frame with the
10890 timestamp @var{start} will be the first frame in the output.
10893 Specify the time of the first frame that will be dropped, i.e. the frame
10894 immediately preceding the one with the timestamp @var{end} will be the last
10895 frame in the output.
10898 This is the same as @var{start}, except this option sets the start timestamp
10899 in timebase units instead of seconds.
10902 This is the same as @var{end}, except this option sets the end timestamp
10903 in timebase units instead of seconds.
10906 The maximum duration of the output in seconds.
10909 The number of the first frame that should be passed to the output.
10912 The number of the first frame that should be dropped.
10915 @option{start}, @option{end}, and @option{duration} are expressed as time
10916 duration specifications; see
10917 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
10918 for the accepted syntax.
10920 Note that the first two sets of the start/end options and the @option{duration}
10921 option look at the frame timestamp, while the _frame variants simply count the
10922 frames that pass through the filter. Also note that this filter does not modify
10923 the timestamps. If you wish for the output timestamps to start at zero, insert a
10924 setpts filter after the trim filter.
10926 If multiple start or end options are set, this filter tries to be greedy and
10927 keep all the frames that match at least one of the specified constraints. To keep
10928 only the part that matches all the constraints at once, chain multiple trim
10931 The defaults are such that all the input is kept. So it is possible to set e.g.
10932 just the end values to keep everything before the specified time.
10937 Drop everything except the second minute of input:
10939 ffmpeg -i INPUT -vf trim=60:120
10943 Keep only the first second:
10945 ffmpeg -i INPUT -vf trim=duration=1
10954 Sharpen or blur the input video.
10956 It accepts the following parameters:
10959 @item luma_msize_x, lx
10960 Set the luma matrix horizontal size. It must be an odd integer between
10961 3 and 63. The default value is 5.
10963 @item luma_msize_y, ly
10964 Set the luma matrix vertical size. It must be an odd integer between 3
10965 and 63. The default value is 5.
10967 @item luma_amount, la
10968 Set the luma effect strength. It must be a floating point number, reasonable
10969 values lay between -1.5 and 1.5.
10971 Negative values will blur the input video, while positive values will
10972 sharpen it, a value of zero will disable the effect.
10974 Default value is 1.0.
10976 @item chroma_msize_x, cx
10977 Set the chroma matrix horizontal size. It must be an odd integer
10978 between 3 and 63. The default value is 5.
10980 @item chroma_msize_y, cy
10981 Set the chroma matrix vertical size. It must be an odd integer
10982 between 3 and 63. The default value is 5.
10984 @item chroma_amount, ca
10985 Set the chroma effect strength. It must be a floating point number, reasonable
10986 values lay between -1.5 and 1.5.
10988 Negative values will blur the input video, while positive values will
10989 sharpen it, a value of zero will disable the effect.
10991 Default value is 0.0.
10994 If set to 1, specify using OpenCL capabilities, only available if
10995 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
10999 All parameters are optional and default to the equivalent of the
11000 string '5:5:1.0:5:5:0.0'.
11002 @subsection Examples
11006 Apply strong luma sharpen effect:
11008 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
11012 Apply a strong blur of both luma and chroma parameters:
11014 unsharp=7:7:-2:7:7:-2
11020 Apply ultra slow/simple postprocessing filter that compresses and decompresses
11021 the image at several (or - in the case of @option{quality} level @code{8} - all)
11022 shifts and average the results.
11024 The way this differs from the behavior of spp is that uspp actually encodes &
11025 decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
11026 DCT similar to MJPEG.
11028 The filter accepts the following options:
11032 Set quality. This option defines the number of levels for averaging. It accepts
11033 an integer in the range 0-8. If set to @code{0}, the filter will have no
11034 effect. A value of @code{8} means the higher quality. For each increment of
11035 that value the speed drops by a factor of approximately 2. Default value is
11039 Force a constant quantization parameter. If not set, the filter will use the QP
11040 from the video stream (if available).
11043 @section vectorscope
11045 Display 2 color component values in the two dimensional graph (which is called
11048 This filter accepts the following options:
11052 Set vectorscope mode.
11054 It accepts the following values:
11057 Gray values are displayed on graph, higher brightness means more pixels have
11058 same component color value on location in graph. This is the default mode.
11061 Gray values are displayed on graph. Surrounding pixels values which are not
11062 present in video frame are drawn in gradient of 2 color components which are
11063 set by option @code{x} and @code{y}.
11066 Actual color components values present in video frame are displayed on graph.
11069 Similar as color2 but higher frequency of same values @code{x} and @code{y}
11070 on graph increases value of another color component, which is luminance by
11071 default values of @code{x} and @code{y}.
11074 Actual colors present in video frame are displayed on graph. If two different
11075 colors map to same position on graph then color with higher value of component
11076 not present in graph is picked.
11080 Set which color component will be represented on X-axis. Default is @code{1}.
11083 Set which color component will be represented on Y-axis. Default is @code{2}.
11086 Set intensity, used by modes: gray, color and color3 for increasing brightness
11087 of color component which represents frequency of (X, Y) location in graph.
11092 No envelope, this is default.
11095 Instant envelope, even darkest single pixel will be clearly highlighted.
11098 Hold maximum and minimum values presented in graph over time. This way you
11099 can still spot out of range values without constantly looking at vectorscope.
11102 Peak and instant envelope combined together.
11106 @anchor{vidstabdetect}
11107 @section vidstabdetect
11109 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
11110 @ref{vidstabtransform} for pass 2.
11112 This filter generates a file with relative translation and rotation
11113 transform information about subsequent frames, which is then used by
11114 the @ref{vidstabtransform} filter.
11116 To enable compilation of this filter you need to configure FFmpeg with
11117 @code{--enable-libvidstab}.
11119 This filter accepts the following options:
11123 Set the path to the file used to write the transforms information.
11124 Default value is @file{transforms.trf}.
11127 Set how shaky the video is and how quick the camera is. It accepts an
11128 integer in the range 1-10, a value of 1 means little shakiness, a
11129 value of 10 means strong shakiness. Default value is 5.
11132 Set the accuracy of the detection process. It must be a value in the
11133 range 1-15. A value of 1 means low accuracy, a value of 15 means high
11134 accuracy. Default value is 15.
11137 Set stepsize of the search process. The region around minimum is
11138 scanned with 1 pixel resolution. Default value is 6.
11141 Set minimum contrast. Below this value a local measurement field is
11142 discarded. Must be a floating point value in the range 0-1. Default
11146 Set reference frame number for tripod mode.
11148 If enabled, the motion of the frames is compared to a reference frame
11149 in the filtered stream, identified by the specified number. The idea
11150 is to compensate all movements in a more-or-less static scene and keep
11151 the camera view absolutely still.
11153 If set to 0, it is disabled. The frames are counted starting from 1.
11156 Show fields and transforms in the resulting frames. It accepts an
11157 integer in the range 0-2. Default value is 0, which disables any
11161 @subsection Examples
11165 Use default values:
11171 Analyze strongly shaky movie and put the results in file
11172 @file{mytransforms.trf}:
11174 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
11178 Visualize the result of internal transformations in the resulting
11181 vidstabdetect=show=1
11185 Analyze a video with medium shakiness using @command{ffmpeg}:
11187 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
11191 @anchor{vidstabtransform}
11192 @section vidstabtransform
11194 Video stabilization/deshaking: pass 2 of 2,
11195 see @ref{vidstabdetect} for pass 1.
11197 Read a file with transform information for each frame and
11198 apply/compensate them. Together with the @ref{vidstabdetect}
11199 filter this can be used to deshake videos. See also
11200 @url{http://public.hronopik.de/vid.stab}. It is important to also use
11201 the @ref{unsharp} filter, see below.
11203 To enable compilation of this filter you need to configure FFmpeg with
11204 @code{--enable-libvidstab}.
11206 @subsection Options
11210 Set path to the file used to read the transforms. Default value is
11211 @file{transforms.trf}.
11214 Set the number of frames (value*2 + 1) used for lowpass filtering the
11215 camera movements. Default value is 10.
11217 For example a number of 10 means that 21 frames are used (10 in the
11218 past and 10 in the future) to smoothen the motion in the video. A
11219 larger value leads to a smoother video, but limits the acceleration of
11220 the camera (pan/tilt movements). 0 is a special case where a static
11221 camera is simulated.
11224 Set the camera path optimization algorithm.
11226 Accepted values are:
11229 gaussian kernel low-pass filter on camera motion (default)
11231 averaging on transformations
11235 Set maximal number of pixels to translate frames. Default value is -1,
11239 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
11240 value is -1, meaning no limit.
11243 Specify how to deal with borders that may be visible due to movement
11246 Available values are:
11249 keep image information from previous frame (default)
11251 fill the border black
11255 Invert transforms if set to 1. Default value is 0.
11258 Consider transforms as relative to previous frame if set to 1,
11259 absolute if set to 0. Default value is 0.
11262 Set percentage to zoom. A positive value will result in a zoom-in
11263 effect, a negative value in a zoom-out effect. Default value is 0 (no
11267 Set optimal zooming to avoid borders.
11269 Accepted values are:
11274 optimal static zoom value is determined (only very strong movements
11275 will lead to visible borders) (default)
11277 optimal adaptive zoom value is determined (no borders will be
11278 visible), see @option{zoomspeed}
11281 Note that the value given at zoom is added to the one calculated here.
11284 Set percent to zoom maximally each frame (enabled when
11285 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
11289 Specify type of interpolation.
11291 Available values are:
11296 linear only horizontal
11298 linear in both directions (default)
11300 cubic in both directions (slow)
11304 Enable virtual tripod mode if set to 1, which is equivalent to
11305 @code{relative=0:smoothing=0}. Default value is 0.
11307 Use also @code{tripod} option of @ref{vidstabdetect}.
11310 Increase log verbosity if set to 1. Also the detected global motions
11311 are written to the temporary file @file{global_motions.trf}. Default
11315 @subsection Examples
11319 Use @command{ffmpeg} for a typical stabilization with default values:
11321 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
11324 Note the use of the @ref{unsharp} filter which is always recommended.
11327 Zoom in a bit more and load transform data from a given file:
11329 vidstabtransform=zoom=5:input="mytransforms.trf"
11333 Smoothen the video even more:
11335 vidstabtransform=smoothing=30
11341 Flip the input video vertically.
11343 For example, to vertically flip a video with @command{ffmpeg}:
11345 ffmpeg -i in.avi -vf "vflip" out.avi
11351 Make or reverse a natural vignetting effect.
11353 The filter accepts the following options:
11357 Set lens angle expression as a number of radians.
11359 The value is clipped in the @code{[0,PI/2]} range.
11361 Default value: @code{"PI/5"}
11365 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
11369 Set forward/backward mode.
11371 Available modes are:
11374 The larger the distance from the central point, the darker the image becomes.
11377 The larger the distance from the central point, the brighter the image becomes.
11378 This can be used to reverse a vignette effect, though there is no automatic
11379 detection to extract the lens @option{angle} and other settings (yet). It can
11380 also be used to create a burning effect.
11383 Default value is @samp{forward}.
11386 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
11388 It accepts the following values:
11391 Evaluate expressions only once during the filter initialization.
11394 Evaluate expressions for each incoming frame. This is way slower than the
11395 @samp{init} mode since it requires all the scalers to be re-computed, but it
11396 allows advanced dynamic expressions.
11399 Default value is @samp{init}.
11402 Set dithering to reduce the circular banding effects. Default is @code{1}
11406 Set vignette aspect. This setting allows one to adjust the shape of the vignette.
11407 Setting this value to the SAR of the input will make a rectangular vignetting
11408 following the dimensions of the video.
11410 Default is @code{1/1}.
11413 @subsection Expressions
11415 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
11416 following parameters.
11421 input width and height
11424 the number of input frame, starting from 0
11427 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
11428 @var{TB} units, NAN if undefined
11431 frame rate of the input video, NAN if the input frame rate is unknown
11434 the PTS (Presentation TimeStamp) of the filtered video frame,
11435 expressed in seconds, NAN if undefined
11438 time base of the input video
11442 @subsection Examples
11446 Apply simple strong vignetting effect:
11452 Make a flickering vignetting:
11454 vignette='PI/4+random(1)*PI/50':eval=frame
11460 Stack input videos vertically.
11462 All streams must be of same pixel format and of same width.
11464 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
11465 to create same output.
11467 The filter accept the following option:
11471 Set number of input streams. Default is 2.
11476 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
11477 Deinterlacing Filter").
11479 Based on the process described by Martin Weston for BBC R&D, and
11480 implemented based on the de-interlace algorithm written by Jim
11481 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
11482 uses filter coefficients calculated by BBC R&D.
11484 There are two sets of filter coefficients, so called "simple":
11485 and "complex". Which set of filter coefficients is used can
11486 be set by passing an optional parameter:
11490 Set the interlacing filter coefficients. Accepts one of the following values:
11494 Simple filter coefficient set.
11496 More-complex filter coefficient set.
11498 Default value is @samp{complex}.
11501 Specify which frames to deinterlace. Accept one of the following values:
11505 Deinterlace all frames,
11507 Only deinterlace frames marked as interlaced.
11510 Default value is @samp{all}.
11514 Video waveform monitor.
11516 The waveform monitor plots color component intensity. By default luminance
11517 only. Each column of the waveform corresponds to a column of pixels in the
11520 It accepts the following options:
11524 Can be either @code{row}, or @code{column}. Default is @code{column}.
11525 In row mode, the graph on the left side represents color component value 0 and
11526 the right side represents value = 255. In column mode, the top side represents
11527 color component value = 0 and bottom side represents value = 255.
11530 Set intensity. Smaller values are useful to find out how many values of the same
11531 luminance are distributed across input rows/columns.
11532 Default value is @code{0.04}. Allowed range is [0, 1].
11535 Set mirroring mode. @code{0} means unmirrored, @code{1} means mirrored.
11536 In mirrored mode, higher values will be represented on the left
11537 side for @code{row} mode and at the top for @code{column} mode. Default is
11538 @code{1} (mirrored).
11542 It accepts the following values:
11545 Presents information identical to that in the @code{parade}, except
11546 that the graphs representing color components are superimposed directly
11549 This display mode makes it easier to spot relative differences or similarities
11550 in overlapping areas of the color components that are supposed to be identical,
11551 such as neutral whites, grays, or blacks.
11554 Display separate graph for the color components side by side in
11555 @code{row} mode or one below the other in @code{column} mode.
11557 Using this display mode makes it easy to spot color casts in the highlights
11558 and shadows of an image, by comparing the contours of the top and the bottom
11559 graphs of each waveform. Since whites, grays, and blacks are characterized
11560 by exactly equal amounts of red, green, and blue, neutral areas of the picture
11561 should display three waveforms of roughly equal width/height. If not, the
11562 correction is easy to perform by making level adjustments the three waveforms.
11564 Default is @code{parade}.
11566 @item components, c
11567 Set which color components to display. Default is 1, which means only luminance
11568 or red color component if input is in RGB colorspace. If is set for example to
11569 7 it will display all 3 (if) available color components.
11574 No envelope, this is default.
11577 Instant envelope, minimum and maximum values presented in graph will be easily
11578 visible even with small @code{step} value.
11581 Hold minimum and maximum values presented in graph across time. This way you
11582 can still spot out of range values without constantly looking at waveforms.
11585 Peak and instant envelope combined together.
11591 No filtering, this is default.
11594 Luma and chroma combined together.
11597 Similar as above, but shows difference between blue and red chroma.
11600 Displays only chroma.
11603 Similar as above, but shows difference between blue and red chroma.
11606 Displays actual color value on waveform.
11611 Apply the xBR high-quality magnification filter which is designed for pixel
11612 art. It follows a set of edge-detection rules, see
11613 @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}.
11615 It accepts the following option:
11619 Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
11620 @code{3xBR} and @code{4} for @code{4xBR}.
11621 Default is @code{3}.
11627 Deinterlace the input video ("yadif" means "yet another deinterlacing
11630 It accepts the following parameters:
11636 The interlacing mode to adopt. It accepts one of the following values:
11639 @item 0, send_frame
11640 Output one frame for each frame.
11641 @item 1, send_field
11642 Output one frame for each field.
11643 @item 2, send_frame_nospatial
11644 Like @code{send_frame}, but it skips the spatial interlacing check.
11645 @item 3, send_field_nospatial
11646 Like @code{send_field}, but it skips the spatial interlacing check.
11649 The default value is @code{send_frame}.
11652 The picture field parity assumed for the input interlaced video. It accepts one
11653 of the following values:
11657 Assume the top field is first.
11659 Assume the bottom field is first.
11661 Enable automatic detection of field parity.
11664 The default value is @code{auto}.
11665 If the interlacing is unknown or the decoder does not export this information,
11666 top field first will be assumed.
11669 Specify which frames to deinterlace. Accept one of the following
11674 Deinterlace all frames.
11675 @item 1, interlaced
11676 Only deinterlace frames marked as interlaced.
11679 The default value is @code{all}.
11684 Apply Zoom & Pan effect.
11686 This filter accepts the following options:
11690 Set the zoom expression. Default is 1.
11694 Set the x and y expression. Default is 0.
11697 Set the duration expression in number of frames.
11698 This sets for how many number of frames effect will last for
11699 single input image.
11702 Set the output image size, default is 'hd720'.
11705 Each expression can contain the following constants:
11724 Output frame count.
11728 Last calculated 'x' and 'y' position from 'x' and 'y' expression
11729 for current input frame.
11733 'x' and 'y' of last output frame of previous input frame or 0 when there was
11734 not yet such frame (first input frame).
11737 Last calculated zoom from 'z' expression for current input frame.
11740 Last calculated zoom of last output frame of previous input frame.
11743 Number of output frames for current input frame. Calculated from 'd' expression
11744 for each input frame.
11747 number of output frames created for previous input frame
11750 Rational number: input width / input height
11753 sample aspect ratio
11756 display aspect ratio
11760 @subsection Examples
11764 Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
11766 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
11770 Zoom-in up to 1.5 and pan always at center of picture:
11772 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
11776 @c man end VIDEO FILTERS
11778 @chapter Video Sources
11779 @c man begin VIDEO SOURCES
11781 Below is a description of the currently available video sources.
11785 Buffer video frames, and make them available to the filter chain.
11787 This source is mainly intended for a programmatic use, in particular
11788 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
11790 It accepts the following parameters:
11795 Specify the size (width and height) of the buffered video frames. For the
11796 syntax of this option, check the
11797 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11800 The input video width.
11803 The input video height.
11806 A string representing the pixel format of the buffered video frames.
11807 It may be a number corresponding to a pixel format, or a pixel format
11811 Specify the timebase assumed by the timestamps of the buffered frames.
11814 Specify the frame rate expected for the video stream.
11816 @item pixel_aspect, sar
11817 The sample (pixel) aspect ratio of the input video.
11820 Specify the optional parameters to be used for the scale filter which
11821 is automatically inserted when an input change is detected in the
11822 input size or format.
11827 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
11830 will instruct the source to accept video frames with size 320x240 and
11831 with format "yuv410p", assuming 1/24 as the timestamps timebase and
11832 square pixels (1:1 sample aspect ratio).
11833 Since the pixel format with name "yuv410p" corresponds to the number 6
11834 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
11835 this example corresponds to:
11837 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
11840 Alternatively, the options can be specified as a flat string, but this
11841 syntax is deprecated:
11843 @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}]
11847 Create a pattern generated by an elementary cellular automaton.
11849 The initial state of the cellular automaton can be defined through the
11850 @option{filename}, and @option{pattern} options. If such options are
11851 not specified an initial state is created randomly.
11853 At each new frame a new row in the video is filled with the result of
11854 the cellular automaton next generation. The behavior when the whole
11855 frame is filled is defined by the @option{scroll} option.
11857 This source accepts the following options:
11861 Read the initial cellular automaton state, i.e. the starting row, from
11862 the specified file.
11863 In the file, each non-whitespace character is considered an alive
11864 cell, a newline will terminate the row, and further characters in the
11865 file will be ignored.
11868 Read the initial cellular automaton state, i.e. the starting row, from
11869 the specified string.
11871 Each non-whitespace character in the string is considered an alive
11872 cell, a newline will terminate the row, and further characters in the
11873 string will be ignored.
11876 Set the video rate, that is the number of frames generated per second.
11879 @item random_fill_ratio, ratio
11880 Set the random fill ratio for the initial cellular automaton row. It
11881 is a floating point number value ranging from 0 to 1, defaults to
11884 This option is ignored when a file or a pattern is specified.
11886 @item random_seed, seed
11887 Set the seed for filling randomly the initial row, must be an integer
11888 included between 0 and UINT32_MAX. If not specified, or if explicitly
11889 set to -1, the filter will try to use a good random seed on a best
11893 Set the cellular automaton rule, it is a number ranging from 0 to 255.
11894 Default value is 110.
11897 Set the size of the output video. For the syntax of this option, check the
11898 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11900 If @option{filename} or @option{pattern} is specified, the size is set
11901 by default to the width of the specified initial state row, and the
11902 height is set to @var{width} * PHI.
11904 If @option{size} is set, it must contain the width of the specified
11905 pattern string, and the specified pattern will be centered in the
11908 If a filename or a pattern string is not specified, the size value
11909 defaults to "320x518" (used for a randomly generated initial state).
11912 If set to 1, scroll the output upward when all the rows in the output
11913 have been already filled. If set to 0, the new generated row will be
11914 written over the top row just after the bottom row is filled.
11917 @item start_full, full
11918 If set to 1, completely fill the output with generated rows before
11919 outputting the first frame.
11920 This is the default behavior, for disabling set the value to 0.
11923 If set to 1, stitch the left and right row edges together.
11924 This is the default behavior, for disabling set the value to 0.
11927 @subsection Examples
11931 Read the initial state from @file{pattern}, and specify an output of
11934 cellauto=f=pattern:s=200x400
11938 Generate a random initial row with a width of 200 cells, with a fill
11941 cellauto=ratio=2/3:s=200x200
11945 Create a pattern generated by rule 18 starting by a single alive cell
11946 centered on an initial row with width 100:
11948 cellauto=p=@@:s=100x400:full=0:rule=18
11952 Specify a more elaborated initial pattern:
11954 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
11959 @section mandelbrot
11961 Generate a Mandelbrot set fractal, and progressively zoom towards the
11962 point specified with @var{start_x} and @var{start_y}.
11964 This source accepts the following options:
11969 Set the terminal pts value. Default value is 400.
11972 Set the terminal scale value.
11973 Must be a floating point value. Default value is 0.3.
11976 Set the inner coloring mode, that is the algorithm used to draw the
11977 Mandelbrot fractal internal region.
11979 It shall assume one of the following values:
11984 Show time until convergence.
11986 Set color based on point closest to the origin of the iterations.
11991 Default value is @var{mincol}.
11994 Set the bailout value. Default value is 10.0.
11997 Set the maximum of iterations performed by the rendering
11998 algorithm. Default value is 7189.
12001 Set outer coloring mode.
12002 It shall assume one of following values:
12004 @item iteration_count
12005 Set iteration cound mode.
12006 @item normalized_iteration_count
12007 set normalized iteration count mode.
12009 Default value is @var{normalized_iteration_count}.
12012 Set frame rate, expressed as number of frames per second. Default
12016 Set frame size. For the syntax of this option, check the "Video
12017 size" section in the ffmpeg-utils manual. Default value is "640x480".
12020 Set the initial scale value. Default value is 3.0.
12023 Set the initial x position. Must be a floating point value between
12024 -100 and 100. Default value is -0.743643887037158704752191506114774.
12027 Set the initial y position. Must be a floating point value between
12028 -100 and 100. Default value is -0.131825904205311970493132056385139.
12033 Generate various test patterns, as generated by the MPlayer test filter.
12035 The size of the generated video is fixed, and is 256x256.
12036 This source is useful in particular for testing encoding features.
12038 This source accepts the following options:
12043 Specify the frame rate of the sourced video, as the number of frames
12044 generated per second. It has to be a string in the format
12045 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
12046 number or a valid video frame rate abbreviation. The default value is
12050 Set the duration of the sourced video. See
12051 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12052 for the accepted syntax.
12054 If not specified, or the expressed duration is negative, the video is
12055 supposed to be generated forever.
12059 Set the number or the name of the test to perform. Supported tests are:
12075 Default value is "all", which will cycle through the list of all tests.
12080 mptestsrc=t=dc_luma
12083 will generate a "dc_luma" test pattern.
12085 @section frei0r_src
12087 Provide a frei0r source.
12089 To enable compilation of this filter you need to install the frei0r
12090 header and configure FFmpeg with @code{--enable-frei0r}.
12092 This source accepts the following parameters:
12097 The size of the video to generate. For the syntax of this option, check the
12098 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12101 The framerate of the generated video. It may be a string of the form
12102 @var{num}/@var{den} or a frame rate abbreviation.
12105 The name to the frei0r source to load. For more information regarding frei0r and
12106 how to set the parameters, read the @ref{frei0r} section in the video filters
12109 @item filter_params
12110 A '|'-separated list of parameters to pass to the frei0r source.
12114 For example, to generate a frei0r partik0l source with size 200x200
12115 and frame rate 10 which is overlaid on the overlay filter main input:
12117 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
12122 Generate a life pattern.
12124 This source is based on a generalization of John Conway's life game.
12126 The sourced input represents a life grid, each pixel represents a cell
12127 which can be in one of two possible states, alive or dead. Every cell
12128 interacts with its eight neighbours, which are the cells that are
12129 horizontally, vertically, or diagonally adjacent.
12131 At each interaction the grid evolves according to the adopted rule,
12132 which specifies the number of neighbor alive cells which will make a
12133 cell stay alive or born. The @option{rule} option allows one to specify
12136 This source accepts the following options:
12140 Set the file from which to read the initial grid state. In the file,
12141 each non-whitespace character is considered an alive cell, and newline
12142 is used to delimit the end of each row.
12144 If this option is not specified, the initial grid is generated
12148 Set the video rate, that is the number of frames generated per second.
12151 @item random_fill_ratio, ratio
12152 Set the random fill ratio for the initial random grid. It is a
12153 floating point number value ranging from 0 to 1, defaults to 1/PHI.
12154 It is ignored when a file is specified.
12156 @item random_seed, seed
12157 Set the seed for filling the initial random grid, must be an integer
12158 included between 0 and UINT32_MAX. If not specified, or if explicitly
12159 set to -1, the filter will try to use a good random seed on a best
12165 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
12166 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
12167 @var{NS} specifies the number of alive neighbor cells which make a
12168 live cell stay alive, and @var{NB} the number of alive neighbor cells
12169 which make a dead cell to become alive (i.e. to "born").
12170 "s" and "b" can be used in place of "S" and "B", respectively.
12172 Alternatively a rule can be specified by an 18-bits integer. The 9
12173 high order bits are used to encode the next cell state if it is alive
12174 for each number of neighbor alive cells, the low order bits specify
12175 the rule for "borning" new cells. Higher order bits encode for an
12176 higher number of neighbor cells.
12177 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
12178 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
12180 Default value is "S23/B3", which is the original Conway's game of life
12181 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
12182 cells, and will born a new cell if there are three alive cells around
12186 Set the size of the output video. For the syntax of this option, check the
12187 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12189 If @option{filename} is specified, the size is set by default to the
12190 same size of the input file. If @option{size} is set, it must contain
12191 the size specified in the input file, and the initial grid defined in
12192 that file is centered in the larger resulting area.
12194 If a filename is not specified, the size value defaults to "320x240"
12195 (used for a randomly generated initial grid).
12198 If set to 1, stitch the left and right grid edges together, and the
12199 top and bottom edges also. Defaults to 1.
12202 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
12203 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
12204 value from 0 to 255.
12207 Set the color of living (or new born) cells.
12210 Set the color of dead cells. If @option{mold} is set, this is the first color
12211 used to represent a dead cell.
12214 Set mold color, for definitely dead and moldy cells.
12216 For the syntax of these 3 color options, check the "Color" section in the
12217 ffmpeg-utils manual.
12220 @subsection Examples
12224 Read a grid from @file{pattern}, and center it on a grid of size
12227 life=f=pattern:s=300x300
12231 Generate a random grid of size 200x200, with a fill ratio of 2/3:
12233 life=ratio=2/3:s=200x200
12237 Specify a custom rule for evolving a randomly generated grid:
12243 Full example with slow death effect (mold) using @command{ffplay}:
12245 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
12252 @anchor{haldclutsrc}
12254 @anchor{rgbtestsrc}
12256 @anchor{smptehdbars}
12258 @section allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
12260 The @code{allrgb} source returns frames of size 4096x4096 of all rgb colors.
12262 The @code{allyuv} source returns frames of size 4096x4096 of all yuv colors.
12264 The @code{color} source provides an uniformly colored input.
12266 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
12267 @ref{haldclut} filter.
12269 The @code{nullsrc} source returns unprocessed video frames. It is
12270 mainly useful to be employed in analysis / debugging tools, or as the
12271 source for filters which ignore the input data.
12273 The @code{rgbtestsrc} source generates an RGB test pattern useful for
12274 detecting RGB vs BGR issues. You should see a red, green and blue
12275 stripe from top to bottom.
12277 The @code{smptebars} source generates a color bars pattern, based on
12278 the SMPTE Engineering Guideline EG 1-1990.
12280 The @code{smptehdbars} source generates a color bars pattern, based on
12281 the SMPTE RP 219-2002.
12283 The @code{testsrc} source generates a test video pattern, showing a
12284 color pattern, a scrolling gradient and a timestamp. This is mainly
12285 intended for testing purposes.
12287 The sources accept the following parameters:
12292 Specify the color of the source, only available in the @code{color}
12293 source. For the syntax of this option, check the "Color" section in the
12294 ffmpeg-utils manual.
12297 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
12298 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
12299 pixels to be used as identity matrix for 3D lookup tables. Each component is
12300 coded on a @code{1/(N*N)} scale.
12303 Specify the size of the sourced video. For the syntax of this option, check the
12304 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12305 The default value is @code{320x240}.
12307 This option is not available with the @code{haldclutsrc} filter.
12310 Specify the frame rate of the sourced video, as the number of frames
12311 generated per second. It has to be a string in the format
12312 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
12313 number or a valid video frame rate abbreviation. The default value is
12317 Set the sample aspect ratio of the sourced video.
12320 Set the duration of the sourced video. See
12321 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12322 for the accepted syntax.
12324 If not specified, or the expressed duration is negative, the video is
12325 supposed to be generated forever.
12328 Set the number of decimals to show in the timestamp, only available in the
12329 @code{testsrc} source.
12331 The displayed timestamp value will correspond to the original
12332 timestamp value multiplied by the power of 10 of the specified
12333 value. Default value is 0.
12336 For example the following:
12338 testsrc=duration=5.3:size=qcif:rate=10
12341 will generate a video with a duration of 5.3 seconds, with size
12342 176x144 and a frame rate of 10 frames per second.
12344 The following graph description will generate a red source
12345 with an opacity of 0.2, with size "qcif" and a frame rate of 10
12348 color=c=red@@0.2:s=qcif:r=10
12351 If the input content is to be ignored, @code{nullsrc} can be used. The
12352 following command generates noise in the luminance plane by employing
12353 the @code{geq} filter:
12355 nullsrc=s=256x256, geq=random(1)*255:128:128
12358 @subsection Commands
12360 The @code{color} source supports the following commands:
12364 Set the color of the created image. Accepts the same syntax of the
12365 corresponding @option{color} option.
12368 @c man end VIDEO SOURCES
12370 @chapter Video Sinks
12371 @c man begin VIDEO SINKS
12373 Below is a description of the currently available video sinks.
12375 @section buffersink
12377 Buffer video frames, and make them available to the end of the filter
12380 This sink is mainly intended for programmatic use, in particular
12381 through the interface defined in @file{libavfilter/buffersink.h}
12382 or the options system.
12384 It accepts a pointer to an AVBufferSinkContext structure, which
12385 defines the incoming buffers' formats, to be passed as the opaque
12386 parameter to @code{avfilter_init_filter} for initialization.
12390 Null video sink: do absolutely nothing with the input video. It is
12391 mainly useful as a template and for use in analysis / debugging
12394 @c man end VIDEO SINKS
12396 @chapter Multimedia Filters
12397 @c man begin MULTIMEDIA FILTERS
12399 Below is a description of the currently available multimedia filters.
12401 @section aphasemeter
12403 Convert input audio to a video output, displaying the audio phase.
12405 The filter accepts the following options:
12409 Set the output frame rate. Default value is @code{25}.
12412 Set the video size for the output. For the syntax of this option, check the
12413 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12414 Default value is @code{800x400}.
12419 Specify the red, green, blue contrast. Default values are @code{2},
12420 @code{7} and @code{1}.
12421 Allowed range is @code{[0, 255]}.
12424 Set color which will be used for drawing median phase. If color is
12425 @code{none} which is default, no median phase value will be drawn.
12428 The filter also exports the frame metadata @code{lavfi.aphasemeter.phase} which
12429 represents mean phase of current audio frame. Value is in range @code{[-1, 1]}.
12430 The @code{-1} means left and right channels are completely out of phase and
12431 @code{1} means channels are in phase.
12433 @section avectorscope
12435 Convert input audio to a video output, representing the audio vector
12438 The filter is used to measure the difference between channels of stereo
12439 audio stream. A monoaural signal, consisting of identical left and right
12440 signal, results in straight vertical line. Any stereo separation is visible
12441 as a deviation from this line, creating a Lissajous figure.
12442 If the straight (or deviation from it) but horizontal line appears this
12443 indicates that the left and right channels are out of phase.
12445 The filter accepts the following options:
12449 Set the vectorscope mode.
12451 Available values are:
12454 Lissajous rotated by 45 degrees.
12457 Same as above but not rotated.
12460 Shape resembling half of circle.
12463 Default value is @samp{lissajous}.
12466 Set the video size for the output. For the syntax of this option, check the
12467 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12468 Default value is @code{400x400}.
12471 Set the output frame rate. Default value is @code{25}.
12477 Specify the red, green, blue and alpha contrast. Default values are @code{40},
12478 @code{160}, @code{80} and @code{255}.
12479 Allowed range is @code{[0, 255]}.
12485 Specify the red, green, blue and alpha fade. Default values are @code{15},
12486 @code{10}, @code{5} and @code{5}.
12487 Allowed range is @code{[0, 255]}.
12490 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
12493 @subsection Examples
12497 Complete example using @command{ffplay}:
12499 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
12500 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
12506 Concatenate audio and video streams, joining them together one after the
12509 The filter works on segments of synchronized video and audio streams. All
12510 segments must have the same number of streams of each type, and that will
12511 also be the number of streams at output.
12513 The filter accepts the following options:
12518 Set the number of segments. Default is 2.
12521 Set the number of output video streams, that is also the number of video
12522 streams in each segment. Default is 1.
12525 Set the number of output audio streams, that is also the number of audio
12526 streams in each segment. Default is 0.
12529 Activate unsafe mode: do not fail if segments have a different format.
12533 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
12534 @var{a} audio outputs.
12536 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
12537 segment, in the same order as the outputs, then the inputs for the second
12540 Related streams do not always have exactly the same duration, for various
12541 reasons including codec frame size or sloppy authoring. For that reason,
12542 related synchronized streams (e.g. a video and its audio track) should be
12543 concatenated at once. The concat filter will use the duration of the longest
12544 stream in each segment (except the last one), and if necessary pad shorter
12545 audio streams with silence.
12547 For this filter to work correctly, all segments must start at timestamp 0.
12549 All corresponding streams must have the same parameters in all segments; the
12550 filtering system will automatically select a common pixel format for video
12551 streams, and a common sample format, sample rate and channel layout for
12552 audio streams, but other settings, such as resolution, must be converted
12553 explicitly by the user.
12555 Different frame rates are acceptable but will result in variable frame rate
12556 at output; be sure to configure the output file to handle it.
12558 @subsection Examples
12562 Concatenate an opening, an episode and an ending, all in bilingual version
12563 (video in stream 0, audio in streams 1 and 2):
12565 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
12566 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
12567 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
12568 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
12572 Concatenate two parts, handling audio and video separately, using the
12573 (a)movie sources, and adjusting the resolution:
12575 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
12576 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
12577 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
12579 Note that a desync will happen at the stitch if the audio and video streams
12580 do not have exactly the same duration in the first file.
12587 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
12588 it unchanged. By default, it logs a message at a frequency of 10Hz with the
12589 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
12590 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
12592 The filter also has a video output (see the @var{video} option) with a real
12593 time graph to observe the loudness evolution. The graphic contains the logged
12594 message mentioned above, so it is not printed anymore when this option is set,
12595 unless the verbose logging is set. The main graphing area contains the
12596 short-term loudness (3 seconds of analysis), and the gauge on the right is for
12597 the momentary loudness (400 milliseconds).
12599 More information about the Loudness Recommendation EBU R128 on
12600 @url{http://tech.ebu.ch/loudness}.
12602 The filter accepts the following options:
12607 Activate the video output. The audio stream is passed unchanged whether this
12608 option is set or no. The video stream will be the first output stream if
12609 activated. Default is @code{0}.
12612 Set the video size. This option is for video only. For the syntax of this
12614 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12615 Default and minimum resolution is @code{640x480}.
12618 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
12619 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
12620 other integer value between this range is allowed.
12623 Set metadata injection. If set to @code{1}, the audio input will be segmented
12624 into 100ms output frames, each of them containing various loudness information
12625 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
12627 Default is @code{0}.
12630 Force the frame logging level.
12632 Available values are:
12635 information logging level
12637 verbose logging level
12640 By default, the logging level is set to @var{info}. If the @option{video} or
12641 the @option{metadata} options are set, it switches to @var{verbose}.
12646 Available modes can be cumulated (the option is a @code{flag} type). Possible
12650 Disable any peak mode (default).
12652 Enable sample-peak mode.
12654 Simple peak mode looking for the higher sample value. It logs a message
12655 for sample-peak (identified by @code{SPK}).
12657 Enable true-peak mode.
12659 If enabled, the peak lookup is done on an over-sampled version of the input
12660 stream for better peak accuracy. It logs a message for true-peak.
12661 (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}).
12662 This mode requires a build with @code{libswresample}.
12667 @subsection Examples
12671 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
12673 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
12677 Run an analysis with @command{ffmpeg}:
12679 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
12683 @section interleave, ainterleave
12685 Temporally interleave frames from several inputs.
12687 @code{interleave} works with video inputs, @code{ainterleave} with audio.
12689 These filters read frames from several inputs and send the oldest
12690 queued frame to the output.
12692 Input streams must have a well defined, monotonically increasing frame
12695 In order to submit one frame to output, these filters need to enqueue
12696 at least one frame for each input, so they cannot work in case one
12697 input is not yet terminated and will not receive incoming frames.
12699 For example consider the case when one input is a @code{select} filter
12700 which always drop input frames. The @code{interleave} filter will keep
12701 reading from that input, but it will never be able to send new frames
12702 to output until the input will send an end-of-stream signal.
12704 Also, depending on inputs synchronization, the filters will drop
12705 frames in case one input receives more frames than the other ones, and
12706 the queue is already filled.
12708 These filters accept the following options:
12712 Set the number of different inputs, it is 2 by default.
12715 @subsection Examples
12719 Interleave frames belonging to different streams using @command{ffmpeg}:
12721 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
12725 Add flickering blur effect:
12727 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
12731 @section perms, aperms
12733 Set read/write permissions for the output frames.
12735 These filters are mainly aimed at developers to test direct path in the
12736 following filter in the filtergraph.
12738 The filters accept the following options:
12742 Select the permissions mode.
12744 It accepts the following values:
12747 Do nothing. This is the default.
12749 Set all the output frames read-only.
12751 Set all the output frames directly writable.
12753 Make the frame read-only if writable, and writable if read-only.
12755 Set each output frame read-only or writable randomly.
12759 Set the seed for the @var{random} mode, must be an integer included between
12760 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
12761 @code{-1}, the filter will try to use a good random seed on a best effort
12765 Note: in case of auto-inserted filter between the permission filter and the
12766 following one, the permission might not be received as expected in that
12767 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
12768 perms/aperms filter can avoid this problem.
12770 @section select, aselect
12772 Select frames to pass in output.
12774 This filter accepts the following options:
12779 Set expression, which is evaluated for each input frame.
12781 If the expression is evaluated to zero, the frame is discarded.
12783 If the evaluation result is negative or NaN, the frame is sent to the
12784 first output; otherwise it is sent to the output with index
12785 @code{ceil(val)-1}, assuming that the input index starts from 0.
12787 For example a value of @code{1.2} corresponds to the output with index
12788 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
12791 Set the number of outputs. The output to which to send the selected
12792 frame is based on the result of the evaluation. Default value is 1.
12795 The expression can contain the following constants:
12799 The (sequential) number of the filtered frame, starting from 0.
12802 The (sequential) number of the selected frame, starting from 0.
12804 @item prev_selected_n
12805 The sequential number of the last selected frame. It's NAN if undefined.
12808 The timebase of the input timestamps.
12811 The PTS (Presentation TimeStamp) of the filtered video frame,
12812 expressed in @var{TB} units. It's NAN if undefined.
12815 The PTS of the filtered video frame,
12816 expressed in seconds. It's NAN if undefined.
12819 The PTS of the previously filtered video frame. It's NAN if undefined.
12821 @item prev_selected_pts
12822 The PTS of the last previously filtered video frame. It's NAN if undefined.
12824 @item prev_selected_t
12825 The PTS of the last previously selected video frame. It's NAN if undefined.
12828 The PTS of the first video frame in the video. It's NAN if undefined.
12831 The time of the first video frame in the video. It's NAN if undefined.
12833 @item pict_type @emph{(video only)}
12834 The type of the filtered frame. It can assume one of the following
12846 @item interlace_type @emph{(video only)}
12847 The frame interlace type. It can assume one of the following values:
12850 The frame is progressive (not interlaced).
12852 The frame is top-field-first.
12854 The frame is bottom-field-first.
12857 @item consumed_sample_n @emph{(audio only)}
12858 the number of selected samples before the current frame
12860 @item samples_n @emph{(audio only)}
12861 the number of samples in the current frame
12863 @item sample_rate @emph{(audio only)}
12864 the input sample rate
12867 This is 1 if the filtered frame is a key-frame, 0 otherwise.
12870 the position in the file of the filtered frame, -1 if the information
12871 is not available (e.g. for synthetic video)
12873 @item scene @emph{(video only)}
12874 value between 0 and 1 to indicate a new scene; a low value reflects a low
12875 probability for the current frame to introduce a new scene, while a higher
12876 value means the current frame is more likely to be one (see the example below)
12880 The default value of the select expression is "1".
12882 @subsection Examples
12886 Select all frames in input:
12891 The example above is the same as:
12903 Select only I-frames:
12905 select='eq(pict_type\,I)'
12909 Select one frame every 100:
12911 select='not(mod(n\,100))'
12915 Select only frames contained in the 10-20 time interval:
12917 select=between(t\,10\,20)
12921 Select only I frames contained in the 10-20 time interval:
12923 select=between(t\,10\,20)*eq(pict_type\,I)
12927 Select frames with a minimum distance of 10 seconds:
12929 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
12933 Use aselect to select only audio frames with samples number > 100:
12935 aselect='gt(samples_n\,100)'
12939 Create a mosaic of the first scenes:
12941 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
12944 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
12948 Send even and odd frames to separate outputs, and compose them:
12950 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
12954 @section sendcmd, asendcmd
12956 Send commands to filters in the filtergraph.
12958 These filters read commands to be sent to other filters in the
12961 @code{sendcmd} must be inserted between two video filters,
12962 @code{asendcmd} must be inserted between two audio filters, but apart
12963 from that they act the same way.
12965 The specification of commands can be provided in the filter arguments
12966 with the @var{commands} option, or in a file specified by the
12967 @var{filename} option.
12969 These filters accept the following options:
12972 Set the commands to be read and sent to the other filters.
12974 Set the filename of the commands to be read and sent to the other
12978 @subsection Commands syntax
12980 A commands description consists of a sequence of interval
12981 specifications, comprising a list of commands to be executed when a
12982 particular event related to that interval occurs. The occurring event
12983 is typically the current frame time entering or leaving a given time
12986 An interval is specified by the following syntax:
12988 @var{START}[-@var{END}] @var{COMMANDS};
12991 The time interval is specified by the @var{START} and @var{END} times.
12992 @var{END} is optional and defaults to the maximum time.
12994 The current frame time is considered within the specified interval if
12995 it is included in the interval [@var{START}, @var{END}), that is when
12996 the time is greater or equal to @var{START} and is lesser than
12999 @var{COMMANDS} consists of a sequence of one or more command
13000 specifications, separated by ",", relating to that interval. The
13001 syntax of a command specification is given by:
13003 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
13006 @var{FLAGS} is optional and specifies the type of events relating to
13007 the time interval which enable sending the specified command, and must
13008 be a non-null sequence of identifier flags separated by "+" or "|" and
13009 enclosed between "[" and "]".
13011 The following flags are recognized:
13014 The command is sent when the current frame timestamp enters the
13015 specified interval. In other words, the command is sent when the
13016 previous frame timestamp was not in the given interval, and the
13020 The command is sent when the current frame timestamp leaves the
13021 specified interval. In other words, the command is sent when the
13022 previous frame timestamp was in the given interval, and the
13026 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
13029 @var{TARGET} specifies the target of the command, usually the name of
13030 the filter class or a specific filter instance name.
13032 @var{COMMAND} specifies the name of the command for the target filter.
13034 @var{ARG} is optional and specifies the optional list of argument for
13035 the given @var{COMMAND}.
13037 Between one interval specification and another, whitespaces, or
13038 sequences of characters starting with @code{#} until the end of line,
13039 are ignored and can be used to annotate comments.
13041 A simplified BNF description of the commands specification syntax
13044 @var{COMMAND_FLAG} ::= "enter" | "leave"
13045 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
13046 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
13047 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
13048 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
13049 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
13052 @subsection Examples
13056 Specify audio tempo change at second 4:
13058 asendcmd=c='4.0 atempo tempo 1.5',atempo
13062 Specify a list of drawtext and hue commands in a file.
13064 # show text in the interval 5-10
13065 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
13066 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
13068 # desaturate the image in the interval 15-20
13069 15.0-20.0 [enter] hue s 0,
13070 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
13072 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
13074 # apply an exponential saturation fade-out effect, starting from time 25
13075 25 [enter] hue s exp(25-t)
13078 A filtergraph allowing to read and process the above command list
13079 stored in a file @file{test.cmd}, can be specified with:
13081 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
13086 @section setpts, asetpts
13088 Change the PTS (presentation timestamp) of the input frames.
13090 @code{setpts} works on video frames, @code{asetpts} on audio frames.
13092 This filter accepts the following options:
13097 The expression which is evaluated for each frame to construct its timestamp.
13101 The expression is evaluated through the eval API and can contain the following
13106 frame rate, only defined for constant frame-rate video
13109 The presentation timestamp in input
13112 The count of the input frame for video or the number of consumed samples,
13113 not including the current frame for audio, starting from 0.
13115 @item NB_CONSUMED_SAMPLES
13116 The number of consumed samples, not including the current frame (only
13119 @item NB_SAMPLES, S
13120 The number of samples in the current frame (only audio)
13122 @item SAMPLE_RATE, SR
13123 The audio sample rate.
13126 The PTS of the first frame.
13129 the time in seconds of the first frame
13132 State whether the current frame is interlaced.
13135 the time in seconds of the current frame
13138 original position in the file of the frame, or undefined if undefined
13139 for the current frame
13142 The previous input PTS.
13145 previous input time in seconds
13148 The previous output PTS.
13151 previous output time in seconds
13154 The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
13158 The wallclock (RTC) time at the start of the movie in microseconds.
13161 The timebase of the input timestamps.
13165 @subsection Examples
13169 Start counting PTS from zero
13171 setpts=PTS-STARTPTS
13175 Apply fast motion effect:
13181 Apply slow motion effect:
13187 Set fixed rate of 25 frames per second:
13193 Set fixed rate 25 fps with some jitter:
13195 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
13199 Apply an offset of 10 seconds to the input PTS:
13205 Generate timestamps from a "live source" and rebase onto the current timebase:
13207 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
13211 Generate timestamps by counting samples:
13218 @section settb, asettb
13220 Set the timebase to use for the output frames timestamps.
13221 It is mainly useful for testing timebase configuration.
13223 It accepts the following parameters:
13228 The expression which is evaluated into the output timebase.
13232 The value for @option{tb} is an arithmetic expression representing a
13233 rational. The expression can contain the constants "AVTB" (the default
13234 timebase), "intb" (the input timebase) and "sr" (the sample rate,
13235 audio only). Default value is "intb".
13237 @subsection Examples
13241 Set the timebase to 1/25:
13247 Set the timebase to 1/10:
13253 Set the timebase to 1001/1000:
13259 Set the timebase to 2*intb:
13265 Set the default timebase value:
13272 Convert input audio to a video output representing
13273 frequency spectrum logarithmically (using constant Q transform with
13274 Brown-Puckette algorithm), with musical tone scale, from E0 to D#10 (10 octaves).
13276 The filter accepts the following options:
13280 Specify transform volume (multiplier) expression. The expression can contain
13283 @item frequency, freq, f
13284 the frequency where transform is evaluated
13285 @item timeclamp, tc
13286 value of timeclamp option
13290 @item a_weighting(f)
13291 A-weighting of equal loudness
13292 @item b_weighting(f)
13293 B-weighting of equal loudness
13294 @item c_weighting(f)
13295 C-weighting of equal loudness
13297 Default value is @code{16}.
13300 Specify transform length expression. The expression can contain variables:
13302 @item frequency, freq, f
13303 the frequency where transform is evaluated
13304 @item timeclamp, tc
13305 value of timeclamp option
13307 Default value is @code{384/f*tc/(384/f+tc)}.
13310 Specify the transform timeclamp. At low frequency, there is trade-off between
13311 accuracy in time domain and frequency domain. If timeclamp is lower,
13312 event in time domain is represented more accurately (such as fast bass drum),
13313 otherwise event in frequency domain is represented more accurately
13314 (such as bass guitar). Acceptable value is [0.1, 1.0]. Default value is @code{0.17}.
13317 Specify the transform coeffclamp. If coeffclamp is lower, transform is
13318 more accurate, otherwise transform is faster. Acceptable value is [0.1, 10.0].
13319 Default value is @code{1.0}.
13322 Specify gamma. Lower gamma makes the spectrum more contrast, higher gamma
13323 makes the spectrum having more range. Acceptable value is [1.0, 7.0].
13324 Default value is @code{3.0}.
13327 Specify gamma of bargraph. Acceptable value is [1.0, 7.0].
13328 Default value is @code{1.0}.
13331 Specify font file for use with freetype. If not specified, use embedded font.
13334 Specify font color expression. This is arithmetic expression that should return
13335 integer value 0xRRGGBB. The expression can contain variables:
13337 @item frequency, freq, f
13338 the frequency where transform is evaluated
13339 @item timeclamp, tc
13340 value of timeclamp option
13345 midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
13346 @item r(x), g(x), b(x)
13347 red, green, and blue value of intensity x
13349 Default value is @code{st(0, (midi(f)-59.5)/12);
13350 st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
13351 r(1-ld(1)) + b(ld(1))}
13354 If set to 1 (the default), the video size is 1920x1080 (full HD),
13355 if set to 0, the video size is 960x540. Use this option to make CPU usage lower.
13358 Specify video fps. Default value is @code{25}.
13361 Specify number of transform per frame, so there are fps*count transforms
13362 per second. Note that audio data rate must be divisible by fps*count.
13363 Default value is @code{6}.
13367 @subsection Examples
13371 Playing audio while showing the spectrum:
13373 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
13377 Same as above, but with frame rate 30 fps:
13379 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
13383 Playing at 960x540 and lower CPU usage:
13385 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fullhd=0:count=3 [out0]'
13389 A1 and its harmonics: A1, A2, (near)E3, A3:
13391 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),
13392 asplit[a][out1]; [a] showcqt [out0]'
13396 Same as above, but with more accuracy in frequency domain (and slower):
13398 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),
13399 asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
13403 B-weighting of equal loudness
13405 volume=16*b_weighting(f)
13411 tlength=100/f*tc/(100/f+tc)
13415 Custom fontcolor, C-note is colored green, others are colored blue
13417 fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))'
13421 Custom gamma, now spectrum is linear to the amplitude.
13430 Convert input audio to video output representing the audio power spectrum.
13431 Audio amplitude is on Y-axis while frequency is on X-axis.
13433 The filter accepts the following options:
13437 Specify size of video. For the syntax of this option, check the
13438 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13439 Default is @code{1024x512}.
13443 This set how each frequency bin will be represented.
13445 It accepts the following values:
13451 Default is @code{bar}.
13454 Set amplitude scale.
13456 It accepts the following values:
13470 Default is @code{log}.
13473 Set frequency scale.
13475 It accepts the following values:
13484 Reverse logarithmic scale.
13486 Default is @code{lin}.
13491 It accepts the following values:
13507 Default is @code{w2048}
13510 Set windowing function.
13512 It accepts the following values:
13529 Default is @code{hanning}.
13532 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
13533 which means optimal overlap for selected window function will be picked.
13536 Set time averaging. Setting this to 0 will display current maximal peaks.
13537 Default is @code{1}, which means time averaging is disabled.
13540 Specify list of colors separated by space or by '|' which will be used to
13541 draw channel frequencies. Unrecognized or missing colors will be replaced
13545 @section showspectrum
13547 Convert input audio to a video output, representing the audio frequency
13550 The filter accepts the following options:
13554 Specify the video size for the output. For the syntax of this option, check the
13555 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13556 Default value is @code{640x512}.
13559 Specify how the spectrum should slide along the window.
13561 It accepts the following values:
13564 the samples start again on the left when they reach the right
13566 the samples scroll from right to left
13568 frames are only produced when the samples reach the right
13571 Default value is @code{replace}.
13574 Specify display mode.
13576 It accepts the following values:
13579 all channels are displayed in the same row
13581 all channels are displayed in separate rows
13584 Default value is @samp{combined}.
13587 Specify display color mode.
13589 It accepts the following values:
13592 each channel is displayed in a separate color
13594 each channel is is displayed using the same color scheme
13597 Default value is @samp{channel}.
13600 Specify scale used for calculating intensity color values.
13602 It accepts the following values:
13607 square root, default
13614 Default value is @samp{sqrt}.
13617 Set saturation modifier for displayed colors. Negative values provide
13618 alternative color scheme. @code{0} is no saturation at all.
13619 Saturation must be in [-10.0, 10.0] range.
13620 Default value is @code{1}.
13623 Set window function.
13625 It accepts the following values:
13628 No samples pre-processing (do not expect this to be faster)
13637 Default value is @code{hann}.
13640 The usage is very similar to the showwaves filter; see the examples in that
13643 @subsection Examples
13647 Large window with logarithmic color scaling:
13649 showspectrum=s=1280x480:scale=log
13653 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
13655 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
13656 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
13660 @section showvolume
13662 Convert input audio volume to a video output.
13664 The filter accepts the following options:
13671 Set border width, allowed range is [0, 5]. Default is 1.
13674 Set channel width, allowed range is [40, 1080]. Default is 400.
13677 Set channel height, allowed range is [1, 100]. Default is 20.
13680 Set fade, allowed range is [1, 255]. Default is 20.
13683 Set volume color expression.
13685 The expression can use the following variables:
13689 Current max volume of channel in dB.
13692 Current channel number, starting from 0.
13696 If set, displays channel names. Default is enabled.
13701 Convert input audio to a video output, representing the samples waves.
13703 The filter accepts the following options:
13707 Specify the video size for the output. For the syntax of this option, check the
13708 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13709 Default value is @code{600x240}.
13714 Available values are:
13717 Draw a point for each sample.
13720 Draw a vertical line for each sample.
13723 Draw a point for each sample and a line between them.
13726 Draw a centered vertical line for each sample.
13729 Default value is @code{point}.
13732 Set the number of samples which are printed on the same column. A
13733 larger value will decrease the frame rate. Must be a positive
13734 integer. This option can be set only if the value for @var{rate}
13735 is not explicitly specified.
13738 Set the (approximate) output frame rate. This is done by setting the
13739 option @var{n}. Default value is "25".
13741 @item split_channels
13742 Set if channels should be drawn separately or overlap. Default value is 0.
13746 @subsection Examples
13750 Output the input file audio and the corresponding video representation
13753 amovie=a.mp3,asplit[out0],showwaves[out1]
13757 Create a synthetic signal and show it with showwaves, forcing a
13758 frame rate of 30 frames per second:
13760 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
13764 @section showwavespic
13766 Convert input audio to a single video frame, representing the samples waves.
13768 The filter accepts the following options:
13772 Specify the video size for the output. For the syntax of this option, check the
13773 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13774 Default value is @code{600x240}.
13776 @item split_channels
13777 Set if channels should be drawn separately or overlap. Default value is 0.
13780 @subsection Examples
13784 Extract a channel split representation of the wave form of a whole audio track
13785 in a 1024x800 picture using @command{ffmpeg}:
13787 ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
13791 @section split, asplit
13793 Split input into several identical outputs.
13795 @code{asplit} works with audio input, @code{split} with video.
13797 The filter accepts a single parameter which specifies the number of outputs. If
13798 unspecified, it defaults to 2.
13800 @subsection Examples
13804 Create two separate outputs from the same input:
13806 [in] split [out0][out1]
13810 To create 3 or more outputs, you need to specify the number of
13813 [in] asplit=3 [out0][out1][out2]
13817 Create two separate outputs from the same input, one cropped and
13820 [in] split [splitout1][splitout2];
13821 [splitout1] crop=100:100:0:0 [cropout];
13822 [splitout2] pad=200:200:100:100 [padout];
13826 Create 5 copies of the input audio with @command{ffmpeg}:
13828 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
13834 Receive commands sent through a libzmq client, and forward them to
13835 filters in the filtergraph.
13837 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
13838 must be inserted between two video filters, @code{azmq} between two
13841 To enable these filters you need to install the libzmq library and
13842 headers and configure FFmpeg with @code{--enable-libzmq}.
13844 For more information about libzmq see:
13845 @url{http://www.zeromq.org/}
13847 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
13848 receives messages sent through a network interface defined by the
13849 @option{bind_address} option.
13851 The received message must be in the form:
13853 @var{TARGET} @var{COMMAND} [@var{ARG}]
13856 @var{TARGET} specifies the target of the command, usually the name of
13857 the filter class or a specific filter instance name.
13859 @var{COMMAND} specifies the name of the command for the target filter.
13861 @var{ARG} is optional and specifies the optional argument list for the
13862 given @var{COMMAND}.
13864 Upon reception, the message is processed and the corresponding command
13865 is injected into the filtergraph. Depending on the result, the filter
13866 will send a reply to the client, adopting the format:
13868 @var{ERROR_CODE} @var{ERROR_REASON}
13872 @var{MESSAGE} is optional.
13874 @subsection Examples
13876 Look at @file{tools/zmqsend} for an example of a zmq client which can
13877 be used to send commands processed by these filters.
13879 Consider the following filtergraph generated by @command{ffplay}
13881 ffplay -dumpgraph 1 -f lavfi "
13882 color=s=100x100:c=red [l];
13883 color=s=100x100:c=blue [r];
13884 nullsrc=s=200x100, zmq [bg];
13885 [bg][l] overlay [bg+l];
13886 [bg+l][r] overlay=x=100 "
13889 To change the color of the left side of the video, the following
13890 command can be used:
13892 echo Parsed_color_0 c yellow | tools/zmqsend
13895 To change the right side:
13897 echo Parsed_color_1 c pink | tools/zmqsend
13900 @c man end MULTIMEDIA FILTERS
13902 @chapter Multimedia Sources
13903 @c man begin MULTIMEDIA SOURCES
13905 Below is a description of the currently available multimedia sources.
13909 This is the same as @ref{movie} source, except it selects an audio
13915 Read audio and/or video stream(s) from a movie container.
13917 It accepts the following parameters:
13921 The name of the resource to read (not necessarily a file; it can also be a
13922 device or a stream accessed through some protocol).
13924 @item format_name, f
13925 Specifies the format assumed for the movie to read, and can be either
13926 the name of a container or an input device. If not specified, the
13927 format is guessed from @var{movie_name} or by probing.
13929 @item seek_point, sp
13930 Specifies the seek point in seconds. The frames will be output
13931 starting from this seek point. The parameter is evaluated with
13932 @code{av_strtod}, so the numerical value may be suffixed by an IS
13933 postfix. The default value is "0".
13936 Specifies the streams to read. Several streams can be specified,
13937 separated by "+". The source will then have as many outputs, in the
13938 same order. The syntax is explained in the ``Stream specifiers''
13939 section in the ffmpeg manual. Two special names, "dv" and "da" specify
13940 respectively the default (best suited) video and audio stream. Default
13941 is "dv", or "da" if the filter is called as "amovie".
13943 @item stream_index, si
13944 Specifies the index of the video stream to read. If the value is -1,
13945 the most suitable video stream will be automatically selected. The default
13946 value is "-1". Deprecated. If the filter is called "amovie", it will select
13947 audio instead of video.
13950 Specifies how many times to read the stream in sequence.
13951 If the value is less than 1, the stream will be read again and again.
13952 Default value is "1".
13954 Note that when the movie is looped the source timestamps are not
13955 changed, so it will generate non monotonically increasing timestamps.
13958 It allows overlaying a second video on top of the main input of
13959 a filtergraph, as shown in this graph:
13961 input -----------> deltapts0 --> overlay --> output
13964 movie --> scale--> deltapts1 -------+
13966 @subsection Examples
13970 Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
13971 on top of the input labelled "in":
13973 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
13974 [in] setpts=PTS-STARTPTS [main];
13975 [main][over] overlay=16:16 [out]
13979 Read from a video4linux2 device, and overlay it on top of the input
13982 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
13983 [in] setpts=PTS-STARTPTS [main];
13984 [main][over] overlay=16:16 [out]
13988 Read the first video stream and the audio stream with id 0x81 from
13989 dvd.vob; the video is connected to the pad named "video" and the audio is
13990 connected to the pad named "audio":
13992 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
13996 @c man end MULTIMEDIA SOURCES