1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, it is possible for filters to have multiple inputs and
8 To illustrate the sorts of things that are possible, we can
9 use a complex filter graph. For example, the following one:
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 splits the stream in two streams, sends one stream through the crop filter
19 and the vflip filter before merging it back with the other stream by
20 overlaying it on top. You can use the following command to achieve this:
23 ffmpeg -i input -vf "[in] split [T1], [T2] overlay=0:H/2 [out]; [T1] crop=iw:ih/2:0:ih/2, vflip [T2]" output
26 The result will be that in output the top half of the video is mirrored
29 Filters are loaded using the @var{-vf} or @var{-af} option passed to
30 @command{ffmpeg} or to @command{ffplay}. Filters in the same linear
31 chain are separated by commas. In our example, @var{split,
32 overlay} are in one linear chain, and @var{crop, vflip} are in
33 another. The points where the linear chains join are labeled by names
34 enclosed in square brackets. In our example, that is @var{[T1]} and
35 @var{[T2]}. The special labels @var{[in]} and @var{[out]} are the points
36 where video is input and output.
38 Some filters take in input a list of parameters: they are specified
39 after the filter name and an equal sign, and are separated from each other
42 There exist so-called @var{source filters} that do not have an
43 audio/video input, and @var{sink filters} that will not have audio/video
46 @c man end FILTERING INTRODUCTION
49 @c man begin GRAPH2DOT
51 The @file{graph2dot} program included in the FFmpeg @file{tools}
52 directory can be used to parse a filter graph description and issue a
53 corresponding textual representation in the dot language.
60 to see how to use @file{graph2dot}.
62 You can then pass the dot description to the @file{dot} program (from
63 the graphviz suite of programs) and obtain a graphical representation
66 For example the sequence of commands:
68 echo @var{GRAPH_DESCRIPTION} | \
69 tools/graph2dot -o graph.tmp && \
70 dot -Tpng graph.tmp -o graph.png && \
74 can be used to create and display an image representing the graph
75 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
76 a complete self-contained graph, with its inputs and outputs explicitly defined.
77 For example if your command line is of the form:
79 ffmpeg -i infile -vf scale=640:360 outfile
81 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
83 nullsrc,scale=640:360,nullsink
85 you may also need to set the @var{nullsrc} parameters and add a @var{format}
86 filter in order to simulate a specific input file.
90 @chapter Filtergraph description
91 @c man begin FILTERGRAPH DESCRIPTION
93 A filtergraph is a directed graph of connected filters. It can contain
94 cycles, and there can be multiple links between a pair of
95 filters. Each link has one input pad on one side connecting it to one
96 filter from which it takes its input, and one output pad on the other
97 side connecting it to the one filter accepting its output.
99 Each filter in a filtergraph is an instance of a filter class
100 registered in the application, which defines the features and the
101 number of input and output pads of the filter.
103 A filter with no input pads is called a "source", a filter with no
104 output pads is called a "sink".
106 @anchor{Filtergraph syntax}
107 @section Filtergraph syntax
109 A filtergraph can be represented using a textual representation, which is
110 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
111 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
112 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
113 @file{libavfilter/avfiltergraph.h}.
115 A filterchain consists of a sequence of connected filters, each one
116 connected to the previous one in the sequence. A filterchain is
117 represented by a list of ","-separated filter descriptions.
119 A filtergraph consists of a sequence of filterchains. A sequence of
120 filterchains is represented by a list of ";"-separated filterchain
123 A filter is represented by a string of the form:
124 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
126 @var{filter_name} is the name of the filter class of which the
127 described filter is an instance of, and has to be the name of one of
128 the filter classes registered in the program.
129 The name of the filter class is optionally followed by a string
132 @var{arguments} is a string which contains the parameters used to
133 initialize the filter instance, and are described in the filter
136 The list of arguments can be quoted using the character "'" as initial
137 and ending mark, and the character '\' for escaping the characters
138 within the quoted text; otherwise the argument string is considered
139 terminated when the next special character (belonging to the set
140 "[]=;,") is encountered.
142 The name and arguments of the filter are optionally preceded and
143 followed by a list of link labels.
144 A link label allows to name a link and associate it to a filter output
145 or input pad. The preceding labels @var{in_link_1}
146 ... @var{in_link_N}, are associated to the filter input pads,
147 the following labels @var{out_link_1} ... @var{out_link_M}, are
148 associated to the output pads.
150 When two link labels with the same name are found in the
151 filtergraph, a link between the corresponding input and output pad is
154 If an output pad is not labelled, it is linked by default to the first
155 unlabelled input pad of the next filter in the filterchain.
156 For example in the filterchain:
158 nullsrc, split[L1], [L2]overlay, nullsink
160 the split filter instance has two output pads, and the overlay filter
161 instance two input pads. The first output pad of split is labelled
162 "L1", the first input pad of overlay is labelled "L2", and the second
163 output pad of split is linked to the second input pad of overlay,
164 which are both unlabelled.
166 In a complete filterchain all the unlabelled filter input and output
167 pads must be connected. A filtergraph is considered valid if all the
168 filter input and output pads of all the filterchains are connected.
170 Libavfilter will automatically insert scale filters where format
171 conversion is required. It is possible to specify swscale flags
172 for those automatically inserted scalers by prepending
173 @code{sws_flags=@var{flags};}
174 to the filtergraph description.
176 Follows a BNF description for the filtergraph syntax:
178 @var{NAME} ::= sequence of alphanumeric characters and '_'
179 @var{LINKLABEL} ::= "[" @var{NAME} "]"
180 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
181 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
182 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
183 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
184 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
187 @section Notes on filtergraph escaping
189 Some filter arguments require the use of special characters, typically
190 @code{:} to separate key=value pairs in a named options list. In this
191 case the user should perform a first level escaping when specifying
192 the filter arguments. For example, consider the following literal
193 string to be embedded in the @ref{drawtext} filter arguments:
195 this is a 'string': may contain one, or more, special characters
198 Since @code{:} is special for the filter arguments syntax, it needs to
199 be escaped, so you get:
201 text=this is a \'string\'\: may contain one, or more, special characters
204 A second level of escaping is required when embedding the filter
205 arguments in a filtergraph description, in order to escape all the
206 filtergraph special characters. Thus the example above becomes:
208 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
211 Finally an additional level of escaping may be needed when writing the
212 filtergraph description in a shell command, which depends on the
213 escaping rules of the adopted shell. For example, assuming that
214 @code{\} is special and needs to be escaped with another @code{\}, the
215 previous string will finally result in:
217 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
220 Sometimes, it might be more convenient to employ quoting in place of
221 escaping. For example the string:
223 Caesar: tu quoque, Brute, fili mi
226 Can be quoted in the filter arguments as:
228 text='Caesar: tu quoque, Brute, fili mi'
231 And finally inserted in a filtergraph like:
233 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
236 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
237 for more information about the escaping and quoting rules adopted by
240 @c man end FILTERGRAPH DESCRIPTION
242 @chapter Audio Filters
243 @c man begin AUDIO FILTERS
245 When you configure your FFmpeg build, you can disable any of the
246 existing filters using @code{--disable-filters}.
247 The configure output will show the audio filters included in your
250 Below is a description of the currently available audio filters.
254 Convert the input audio format to the specified formats.
256 The filter accepts a string of the form:
257 "@var{sample_format}:@var{channel_layout}".
259 @var{sample_format} specifies the sample format, and can be a string or the
260 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
261 suffix for a planar sample format.
263 @var{channel_layout} specifies the channel layout, and can be a string
264 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
266 The special parameter "auto", signifies that the filter will
267 automatically select the output format depending on the output filter.
269 Some examples follow.
273 Convert input to float, planar, stereo:
279 Convert input to unsigned 8-bit, automatically select out channel layout:
287 Apply a two-pole all-pass filter with central frequency (in Hz)
288 @var{frequency}, and filter-width @var{width}.
289 An all-pass filter changes the audio's frequency to phase relationship
290 without changing its frequency to amplitude relationship.
292 The filter accepts parameters as a list of @var{key}=@var{value}
293 pairs, separated by ":".
295 A description of the accepted parameters follows.
302 Set method to specify band-width of filter.
315 Specify the band-width of a filter in width_type units.
320 Apply a high-pass filter with 3dB point frequency.
321 The filter can be either single-pole, or double-pole (the default).
322 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
324 The filter accepts parameters as a list of @var{key}=@var{value}
325 pairs, separated by ":".
327 A description of the accepted parameters follows.
331 Set frequency in Hz. Default is 3000.
334 Set number of poles. Default is 2.
337 Set method to specify band-width of filter.
350 Specify the band-width of a filter in width_type units.
351 Applies only to double-pole filter.
352 The default is 0.707q and gives a Butterworth response.
357 Apply a low-pass filter with 3dB point frequency.
358 The filter can be either single-pole or double-pole (the default).
359 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
361 The filter accepts parameters as a list of @var{key}=@var{value}
362 pairs, separated by ":".
364 A description of the accepted parameters follows.
368 Set frequency in Hz. Default is 500.
371 Set number of poles. Default is 2.
374 Set method to specify band-width of filter.
387 Specify the band-width of a filter in width_type units.
388 Applies only to double-pole filter.
389 The default is 0.707q and gives a Butterworth response.
394 Boost or cut the bass (lower) frequencies of the audio using a two-pole
395 shelving filter with a response similar to that of a standard
396 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
398 The filter accepts parameters as a list of @var{key}=@var{value}
399 pairs, separated by ":".
401 A description of the accepted parameters follows.
405 Give the gain at 0 Hz. Its useful range is about -20
406 (for a large cut) to +20 (for a large boost).
407 Beware of clipping when using a positive gain.
410 Set the filter's central frequency and so can be used
411 to extend or reduce the frequency range to be boosted or cut.
412 The default value is @code{100} Hz.
415 Set method to specify band-width of filter.
428 Determine how steep is the filter's shelf transition.
433 Boost or cut treble (upper) frequencies of the audio using a two-pole
434 shelving filter with a response similar to that of a standard
435 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
437 The filter accepts parameters as a list of @var{key}=@var{value}
438 pairs, separated by ":".
440 A description of the accepted parameters follows.
444 Give the gain at whichever is the lower of ~22 kHz and the
445 Nyquist frequency. Its useful range is about -20 (for a large cut)
446 to +20 (for a large boost). Beware of clipping when using a positive gain.
449 Set the filter's central frequency and so can be used
450 to extend or reduce the frequency range to be boosted or cut.
451 The default value is @code{3000} Hz.
454 Set method to specify band-width of filter.
467 Determine how steep is the filter's shelf transition.
472 Apply a two-pole Butterworth band-pass filter with central
473 frequency @var{frequency}, and (3dB-point) band-width width.
474 The @var{csg} option selects a constant skirt gain (peak gain = Q)
475 instead of the default: constant 0dB peak gain.
476 The filter roll off at 6dB per octave (20dB per decade).
478 The filter accepts parameters as a list of @var{key}=@var{value}
479 pairs, separated by ":".
481 A description of the accepted parameters follows.
485 Set the filter's central frequency. Default is @code{3000}.
488 Constant skirt gain if set to 1. Defaults to 0.
491 Set method to specify band-width of filter.
504 Specify the band-width of a filter in width_type units.
509 Apply a two-pole Butterworth band-reject filter with central
510 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
511 The filter roll off at 6dB per octave (20dB per decade).
513 The filter accepts parameters as a list of @var{key}=@var{value}
514 pairs, separated by ":".
516 A description of the accepted parameters follows.
520 Set the filter's central frequency. Default is @code{3000}.
523 Set method to specify band-width of filter.
536 Specify the band-width of a filter in width_type units.
541 Apply a biquad IIR filter with the given coefficients.
542 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
543 are the numerator and denominator coefficients respectively.
547 Apply a two-pole peaking equalisation (EQ) filter. With this
548 filter, the signal-level at and around a selected frequency can
549 be increased or decreased, whilst (unlike bandpass and bandreject
550 filters) that at all other frequencies is unchanged.
552 In order to produce complex equalisation curves, this filter can
553 be given several times, each with a different central frequency.
555 The filter accepts parameters as a list of @var{key}=@var{value}
556 pairs, separated by ":".
558 A description of the accepted parameters follows.
562 Set the filter's central frequency in Hz.
565 Set method to specify band-width of filter.
578 Specify the band-width of a filter in width_type units.
581 Set the required gain or attenuation in dB.
582 Beware of clipping when using a positive gain.
587 Apply fade-in/out effect to input audio.
589 The filter accepts parameters as a list of @var{key}=@var{value}
590 pairs, separated by ":".
592 A description of the accepted parameters follows.
596 Specify the effect type, can be either @code{in} for fade-in, or
597 @code{out} for a fade-out effect. Default is @code{in}.
599 @item start_sample, ss
600 Specify the number of the start sample for starting to apply the fade
601 effect. Default is 0.
604 Specify the number of samples for which the fade effect has to last. At
605 the end of the fade-in effect the output audio will have the same
606 volume as the input audio, at the end of the fade-out transition
607 the output audio will be silence. Default is 44100.
610 Specify time in seconds for starting to apply the fade
611 effect. Default is 0.
612 If set this option is used instead of @var{start_sample} one.
615 Specify the number of seconds for which the fade effect has to last. At
616 the end of the fade-in effect the output audio will have the same
617 volume as the input audio, at the end of the fade-out transition
618 the output audio will be silence. Default is 0.
619 If set this option is used instead of @var{nb_samples} one.
622 Set curve for fade transition.
624 It accepts the following values:
627 select triangular, linear slope (default)
629 select quarter of sine wave
631 select half of sine wave
633 select exponential sine wave
637 select inverted parabola
652 Fade in first 15 seconds of audio:
658 Fade out last 25 seconds of a 900 seconds audio:
660 afade=t=out:ss=875:d=25
666 Set output format constraints for the input audio. The framework will
667 negotiate the most appropriate format to minimize conversions.
669 The filter accepts the following named parameters:
673 A comma-separated list of requested sample formats.
676 A comma-separated list of requested sample rates.
678 @item channel_layouts
679 A comma-separated list of requested channel layouts.
683 If a parameter is omitted, all values are allowed.
685 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
687 aformat='sample_fmts=u8,s16:channel_layouts=stereo'
692 Merge two or more audio streams into a single multi-channel stream.
694 The filter accepts the following named options:
699 Set the number of inputs. Default is 2.
703 If the channel layouts of the inputs are disjoint, and therefore compatible,
704 the channel layout of the output will be set accordingly and the channels
705 will be reordered as necessary. If the channel layouts of the inputs are not
706 disjoint, the output will have all the channels of the first input then all
707 the channels of the second input, in that order, and the channel layout of
708 the output will be the default value corresponding to the total number of
711 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
712 is FC+BL+BR, then the output will be in 5.1, with the channels in the
713 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
714 first input, b1 is the first channel of the second input).
716 On the other hand, if both input are in stereo, the output channels will be
717 in the default order: a1, a2, b1, b2, and the channel layout will be
718 arbitrarily set to 4.0, which may or may not be the expected value.
720 All inputs must have the same sample rate, and format.
722 If inputs do not have the same duration, the output will stop with the
725 Example: merge two mono files into a stereo stream:
727 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
730 Example: multiple merges:
733 amovie=input.mkv:si=0 [a0];
734 amovie=input.mkv:si=1 [a1];
735 amovie=input.mkv:si=2 [a2];
736 amovie=input.mkv:si=3 [a3];
737 amovie=input.mkv:si=4 [a4];
738 amovie=input.mkv:si=5 [a5];
739 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
744 Mixes multiple audio inputs into a single output.
748 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
750 will mix 3 input audio streams to a single output with the same duration as the
751 first input and a dropout transition time of 3 seconds.
753 The filter accepts the following named parameters:
757 Number of inputs. If unspecified, it defaults to 2.
760 How to determine the end-of-stream.
764 Duration of longest input. (default)
767 Duration of shortest input.
770 Duration of first input.
774 @item dropout_transition
775 Transition time, in seconds, for volume renormalization when an input
776 stream ends. The default value is 2 seconds.
782 Pass the audio source unchanged to the output.
786 Pad the end of a audio stream with silence, this can be used together with
787 -shortest to extend audio streams to the same length as the video stream.
792 Resample the input audio to the specified parameters, using the
793 libswresample library. If none are specified then the filter will
794 automatically convert between its input and output.
796 This filter is also able to stretch/squeeze the audio data to make it match
797 the timestamps or to inject silence / cut out audio to make it match the
798 timestamps, do a combination of both or do neither.
800 The filter accepts the syntax
801 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
802 expresses a sample rate and @var{resampler_options} is a list of
803 @var{key}=@var{value} pairs, separated by ":". See the
804 ffmpeg-resampler manual for the complete list of supported options.
806 For example, to resample the input audio to 44100Hz:
811 To stretch/squeeze samples to the given timestamps, with a maximum of 1000
812 samples per second compensation:
817 @section asetnsamples
819 Set the number of samples per each output audio frame.
821 The last output packet may contain a different number of samples, as
822 the filter will flush all the remaining samples when the input audio
825 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
830 @item nb_out_samples, n
831 Set the number of frames per each output audio frame. The number is
832 intended as the number of samples @emph{per each channel}.
833 Default value is 1024.
836 If set to 1, the filter will pad the last audio frame with zeroes, so
837 that the last frame will contain the same number of samples as the
838 previous ones. Default value is 1.
841 For example, to set the number of per-frame samples to 1234 and
842 disable padding for the last frame, use:
844 asetnsamples=n=1234:p=0
849 Show a line containing various information for each input audio frame.
850 The input audio is not modified.
852 The shown line contains a sequence of key/value pairs of the form
853 @var{key}:@var{value}.
855 A description of each shown parameter follows:
859 sequential number of the input frame, starting from 0
862 Presentation timestamp of the input frame, in time base units; the time base
863 depends on the filter input pad, and is usually 1/@var{sample_rate}.
866 presentation timestamp of the input frame in seconds
869 position of the frame in the input stream, -1 if this information in
870 unavailable and/or meaningless (for example in case of synthetic audio)
879 sample rate for the audio frame
882 number of samples (per channel) in the frame
885 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
886 the data is treated as if all the planes were concatenated.
888 @item plane_checksums
889 A list of Adler-32 checksums for each data plane.
894 Split input audio into several identical outputs.
896 The filter accepts a single parameter which specifies the number of outputs. If
897 unspecified, it defaults to 2.
901 [in] asplit [out0][out1]
904 will create two separate outputs from the same input.
906 To create 3 or more outputs, you need to specify the number of
909 [in] asplit=3 [out0][out1][out2]
913 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
915 will create 5 copies of the input audio.
920 Forward two audio streams and control the order the buffers are forwarded.
922 The argument to the filter is an expression deciding which stream should be
923 forwarded next: if the result is negative, the first stream is forwarded; if
924 the result is positive or zero, the second stream is forwarded. It can use
925 the following variables:
929 number of buffers forwarded so far on each stream
931 number of samples forwarded so far on each stream
933 current timestamp of each stream
936 The default value is @code{t1-t2}, which means to always forward the stream
937 that has a smaller timestamp.
939 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
940 input, while avoiding too much of a desynchronization:
942 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
943 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
951 The filter accepts exactly one parameter, the audio tempo. If not
952 specified then the filter will assume nominal 1.0 tempo. Tempo must
953 be in the [0.5, 2.0] range.
955 For example, to slow down audio to 80% tempo:
960 For example, to speed up audio to 125% tempo:
967 Make audio easier to listen to on headphones.
969 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
970 so that when listened to on headphones the stereo image is moved from
971 inside your head (standard for headphones) to outside and in front of
972 the listener (standard for speakers).
978 Mix channels with specific gain levels. The filter accepts the output
979 channel layout followed by a set of channels definitions.
981 This filter is also designed to remap efficiently the channels of an audio
984 The filter accepts parameters of the form:
985 "@var{l}:@var{outdef}:@var{outdef}:..."
989 output channel layout or number of channels
992 output channel specification, of the form:
993 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
996 output channel to define, either a channel name (FL, FR, etc.) or a channel
997 number (c0, c1, etc.)
1000 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1003 input channel to use, see out_name for details; it is not possible to mix
1004 named and numbered input channels
1007 If the `=' in a channel specification is replaced by `<', then the gains for
1008 that specification will be renormalized so that the total is 1, thus
1009 avoiding clipping noise.
1011 @subsection Mixing examples
1013 For example, if you want to down-mix from stereo to mono, but with a bigger
1014 factor for the left channel:
1016 pan=1:c0=0.9*c0+0.1*c1
1019 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1020 7-channels surround:
1022 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1025 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1026 that should be preferred (see "-ac" option) unless you have very specific
1029 @subsection Remapping examples
1031 The channel remapping will be effective if, and only if:
1034 @item gain coefficients are zeroes or ones,
1035 @item only one input per channel output,
1038 If all these conditions are satisfied, the filter will notify the user ("Pure
1039 channel mapping detected"), and use an optimized and lossless method to do the
1042 For example, if you have a 5.1 source and want a stereo audio stream by
1043 dropping the extra channels:
1045 pan="stereo: c0=FL : c1=FR"
1048 Given the same source, you can also switch front left and front right channels
1049 and keep the input channel layout:
1051 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1054 If the input is a stereo audio stream, you can mute the front left channel (and
1055 still keep the stereo channel layout) with:
1060 Still with a stereo audio stream input, you can copy the right channel in both
1061 front left and right:
1063 pan="stereo: c0=FR : c1=FR"
1066 @section silencedetect
1068 Detect silence in an audio stream.
1070 This filter logs a message when it detects that the input audio volume is less
1071 or equal to a noise tolerance value for a duration greater or equal to the
1072 minimum detected noise duration.
1074 The printed times and duration are expressed in seconds.
1078 Set silence duration until notification (default is 2 seconds).
1081 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1082 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1085 Detect 5 seconds of silence with -50dB noise tolerance:
1087 silencedetect=n=-50dB:d=5
1090 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1091 tolerance in @file{silence.mp3}:
1093 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1097 Synchronize audio data with timestamps by squeezing/stretching it and/or
1098 dropping samples/adding silence when needed.
1100 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1102 The filter accepts the following named parameters:
1106 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1107 by default. When disabled, time gaps are covered with silence.
1110 Minimum difference between timestamps and audio data (in seconds) to trigger
1111 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1112 this filter, try setting this parameter to 0.
1115 Maximum compensation in samples per second. Relevant only with compensate=1.
1119 Assume the first pts should be this value. The time base is 1 / sample rate.
1120 This allows for padding/trimming at the start of stream. By default, no
1121 assumption is made about the first frame's expected pts, so no padding or
1122 trimming is done. For example, this could be set to 0 to pad the beginning with
1123 silence if an audio stream starts after the video stream or to trim any samples
1124 with a negative pts due to encoder delay.
1128 @section channelsplit
1129 Split each channel in input audio stream into a separate output stream.
1131 This filter accepts the following named parameters:
1133 @item channel_layout
1134 Channel layout of the input stream. Default is "stereo".
1137 For example, assuming a stereo input MP3 file
1139 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1141 will create an output Matroska file with two audio streams, one containing only
1142 the left channel and the other the right channel.
1144 To split a 5.1 WAV file into per-channel files
1146 ffmpeg -i in.wav -filter_complex
1147 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1148 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1149 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1154 Remap input channels to new locations.
1156 This filter accepts the following named parameters:
1158 @item channel_layout
1159 Channel layout of the output stream.
1162 Map channels from input to output. The argument is a comma-separated list of
1163 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1164 @var{in_channel} form. @var{in_channel} can be either the name of the input
1165 channel (e.g. FL for front left) or its index in the input channel layout.
1166 @var{out_channel} is the name of the output channel or its index in the output
1167 channel layout. If @var{out_channel} is not given then it is implicitly an
1168 index, starting with zero and increasing by one for each mapping.
1171 If no mapping is present, the filter will implicitly map input channels to
1172 output channels preserving index.
1174 For example, assuming a 5.1+downmix input MOV file
1176 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
1178 will create an output WAV file tagged as stereo from the downmix channels of
1181 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1183 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
1187 Join multiple input streams into one multi-channel stream.
1189 The filter accepts the following named parameters:
1193 Number of input streams. Defaults to 2.
1195 @item channel_layout
1196 Desired output channel layout. Defaults to stereo.
1199 Map channels from inputs to output. The argument is a comma-separated list of
1200 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1201 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1202 can be either the name of the input channel (e.g. FL for front left) or its
1203 index in the specified input stream. @var{out_channel} is the name of the output
1207 The filter will attempt to guess the mappings when those are not specified
1208 explicitly. It does so by first trying to find an unused matching input channel
1209 and if that fails it picks the first unused input channel.
1211 E.g. to join 3 inputs (with properly set channel layouts)
1213 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1216 To build a 5.1 output from 6 single-channel streams:
1218 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1219 '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'
1224 Convert the audio sample format, sample rate and channel layout. This filter is
1225 not meant to be used directly.
1229 Adjust the input audio volume.
1231 The filter accepts the following named parameters. If the key of the
1232 first options is omitted, the arguments are interpreted according to
1233 the following syntax:
1235 volume=@var{volume}:@var{precision}
1241 Expresses how the audio volume will be increased or decreased.
1243 Output values are clipped to the maximum value.
1245 The output audio volume is given by the relation:
1247 @var{output_volume} = @var{volume} * @var{input_volume}
1250 Default value for @var{volume} is 1.0.
1253 Set the mathematical precision.
1255 This determines which input sample formats will be allowed, which affects the
1256 precision of the volume scaling.
1260 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1262 32-bit floating-point; limits input sample format to FLT. (default)
1264 64-bit floating-point; limits input sample format to DBL.
1268 @subsection Examples
1272 Halve the input audio volume:
1276 volume=volume=-6.0206dB
1279 In all the above example the named key for @option{volume} can be
1280 omitted, for example like in:
1286 Increase input audio power by 6 decibels using fixed-point precision:
1288 volume=volume=6dB:precision=fixed
1292 @section volumedetect
1294 Detect the volume of the input video.
1296 The filter has no parameters. The input is not modified. Statistics about
1297 the volume will be printed in the log when the input stream end is reached.
1299 In particular it will show the mean volume (root mean square), maximum
1300 volume (on a per-sample basis), and the beginning of an histogram of the
1301 registered volume values (from the maximum value to a cumulated 1/1000 of
1304 All volumes are in decibels relative to the maximum PCM value.
1306 Here is an excerpt of the output:
1308 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1309 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1310 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1311 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1312 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1313 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1314 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1315 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1316 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1322 The mean square energy is approximately -27 dB, or 10^-2.7.
1324 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1326 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1329 In other words, raising the volume by +4 dB does not cause any clipping,
1330 raising it by +5 dB causes clipping for 6 samples, etc.
1332 @c man end AUDIO FILTERS
1334 @chapter Audio Sources
1335 @c man begin AUDIO SOURCES
1337 Below is a description of the currently available audio sources.
1341 Buffer audio frames, and make them available to the filter chain.
1343 This source is mainly intended for a programmatic use, in particular
1344 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1346 It accepts the following mandatory parameters:
1347 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1352 The sample rate of the incoming audio buffers.
1355 The sample format of the incoming audio buffers.
1356 Either a sample format name or its corresponging integer representation from
1357 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1359 @item channel_layout
1360 The channel layout of the incoming audio buffers.
1361 Either a channel layout name from channel_layout_map in
1362 @file{libavutil/channel_layout.c} or its corresponding integer representation
1363 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1366 The number of channels of the incoming audio buffers.
1367 If both @var{channels} and @var{channel_layout} are specified, then they
1374 abuffer=44100:s16p:stereo
1377 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1378 Since the sample format with name "s16p" corresponds to the number
1379 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1387 Generate an audio signal specified by an expression.
1389 This source accepts in input one or more expressions (one for each
1390 channel), which are evaluated and used to generate a corresponding
1393 It accepts the syntax: @var{exprs}[::@var{options}].
1394 @var{exprs} is a list of expressions separated by ":", one for each
1395 separate channel. In case the @var{channel_layout} is not
1396 specified, the selected channel layout depends on the number of
1397 provided expressions.
1399 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1402 The description of the accepted options follows.
1406 @item channel_layout, c
1407 Set the channel layout. The number of channels in the specified layout
1408 must be equal to the number of specified expressions.
1411 Set the minimum duration of the sourced audio. See the function
1412 @code{av_parse_time()} for the accepted format.
1413 Note that the resulting duration may be greater than the specified
1414 duration, as the generated audio is always cut at the end of a
1417 If not specified, or the expressed duration is negative, the audio is
1418 supposed to be generated forever.
1421 Set the number of samples per channel per each output frame,
1424 @item sample_rate, s
1425 Specify the sample rate, default to 44100.
1428 Each expression in @var{exprs} can contain the following constants:
1432 number of the evaluated sample, starting from 0
1435 time of the evaluated sample expressed in seconds, starting from 0
1442 @subsection Examples
1454 Generate a sin signal with frequency of 440 Hz, set sample rate to
1457 aevalsrc="sin(440*2*PI*t)::s=8000"
1461 Generate a two channels signal, specify the channel layout (Front
1462 Center + Back Center) explicitly:
1464 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1468 Generate white noise:
1470 aevalsrc="-2+random(0)"
1474 Generate an amplitude modulated signal:
1476 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1480 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1482 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1489 Null audio source, return unprocessed audio frames. It is mainly useful
1490 as a template and to be employed in analysis / debugging tools, or as
1491 the source for filters which ignore the input data (for example the sox
1494 It accepts an optional sequence of @var{key}=@var{value} pairs,
1497 The description of the accepted options follows.
1501 @item sample_rate, s
1502 Specify the sample rate, and defaults to 44100.
1504 @item channel_layout, cl
1506 Specify the channel layout, and can be either an integer or a string
1507 representing a channel layout. The default value of @var{channel_layout}
1510 Check the channel_layout_map definition in
1511 @file{libavutil/channel_layout.c} for the mapping between strings and
1512 channel layout values.
1515 Set the number of samples per requested frames.
1519 Follow some examples:
1521 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1522 anullsrc=r=48000:cl=4
1525 anullsrc=r=48000:cl=mono
1529 Buffer audio frames, and make them available to the filter chain.
1531 This source is not intended to be part of user-supplied graph descriptions but
1532 for insertion by calling programs through the interface defined in
1533 @file{libavfilter/buffersrc.h}.
1535 It accepts the following named parameters:
1539 Timebase which will be used for timestamps of submitted frames. It must be
1540 either a floating-point number or in @var{numerator}/@var{denominator} form.
1546 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1548 @item channel_layout
1549 Channel layout of the audio data, in the form that can be accepted by
1550 @code{av_get_channel_layout()}.
1553 All the parameters need to be explicitly defined.
1557 Synthesize a voice utterance using the libflite library.
1559 To enable compilation of this filter you need to configure FFmpeg with
1560 @code{--enable-libflite}.
1562 Note that the flite library is not thread-safe.
1564 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1567 The description of the accepted parameters follows.
1572 If set to 1, list the names of the available voices and exit
1573 immediately. Default value is 0.
1576 Set the maximum number of samples per frame. Default value is 512.
1579 Set the filename containing the text to speak.
1582 Set the text to speak.
1585 Set the voice to use for the speech synthesis. Default value is
1586 @code{kal}. See also the @var{list_voices} option.
1589 @subsection Examples
1593 Read from file @file{speech.txt}, and synthetize the text using the
1594 standard flite voice:
1596 flite=textfile=speech.txt
1600 Read the specified text selecting the @code{slt} voice:
1602 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1606 Input text to ffmpeg:
1608 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1612 Make @file{ffplay} speak the specified text, using @code{flite} and
1613 the @code{lavfi} device:
1615 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1619 For more information about libflite, check:
1620 @url{http://www.speech.cs.cmu.edu/flite/}
1622 @c man end AUDIO SOURCES
1624 @chapter Audio Sinks
1625 @c man begin AUDIO SINKS
1627 Below is a description of the currently available audio sinks.
1629 @section abuffersink
1631 Buffer audio frames, and make them available to the end of filter chain.
1633 This sink is mainly intended for programmatic use, in particular
1634 through the interface defined in @file{libavfilter/buffersink.h}.
1636 It requires a pointer to an AVABufferSinkContext structure, which
1637 defines the incoming buffers' formats, to be passed as the opaque
1638 parameter to @code{avfilter_init_filter} for initialization.
1642 Null audio sink, do absolutely nothing with the input audio. It is
1643 mainly useful as a template and to be employed in analysis / debugging
1646 @section abuffersink
1647 This sink is intended for programmatic use. Frames that arrive on this sink can
1648 be retrieved by the calling program using the interface defined in
1649 @file{libavfilter/buffersink.h}.
1651 This filter accepts no parameters.
1653 @c man end AUDIO SINKS
1655 @chapter Video Filters
1656 @c man begin VIDEO FILTERS
1658 When you configure your FFmpeg build, you can disable any of the
1659 existing filters using @code{--disable-filters}.
1660 The configure output will show the video filters included in your
1663 Below is a description of the currently available video filters.
1665 @section alphaextract
1667 Extract the alpha component from the input as a grayscale video. This
1668 is especially useful with the @var{alphamerge} filter.
1672 Add or replace the alpha component of the primary input with the
1673 grayscale value of a second input. This is intended for use with
1674 @var{alphaextract} to allow the transmission or storage of frame
1675 sequences that have alpha in a format that doesn't support an alpha
1678 For example, to reconstruct full frames from a normal YUV-encoded video
1679 and a separate video created with @var{alphaextract}, you might use:
1681 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1684 Since this filter is designed for reconstruction, it operates on frame
1685 sequences without considering timestamps, and terminates when either
1686 input reaches end of stream. This will cause problems if your encoding
1687 pipeline drops frames. If you're trying to apply an image as an
1688 overlay to a video stream, consider the @var{overlay} filter instead.
1692 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1693 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1694 Substation Alpha) subtitles files.
1698 Compute the bounding box for the non-black pixels in the input frame
1701 This filter computes the bounding box containing all the pixels with a
1702 luminance value greater than the minimum allowed value.
1703 The parameters describing the bounding box are printed on the filter
1706 @section blackdetect
1708 Detect video intervals that are (almost) completely black. Can be
1709 useful to detect chapter transitions, commercials, or invalid
1710 recordings. Output lines contains the time for the start, end and
1711 duration of the detected black interval expressed in seconds.
1713 In order to display the output lines, you need to set the loglevel at
1714 least to the AV_LOG_INFO value.
1716 This filter accepts a list of options in the form of
1717 @var{key}=@var{value} pairs separated by ":". A description of the
1718 accepted options follows.
1721 @item black_min_duration, d
1722 Set the minimum detected black duration expressed in seconds. It must
1723 be a non-negative floating point number.
1725 Default value is 2.0.
1727 @item picture_black_ratio_th, pic_th
1728 Set the threshold for considering a picture "black".
1729 Express the minimum value for the ratio:
1731 @var{nb_black_pixels} / @var{nb_pixels}
1734 for which a picture is considered black.
1735 Default value is 0.98.
1737 @item pixel_black_th, pix_th
1738 Set the threshold for considering a pixel "black".
1740 The threshold expresses the maximum pixel luminance value for which a
1741 pixel is considered "black". The provided value is scaled according to
1742 the following equation:
1744 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1747 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1748 the input video format, the range is [0-255] for YUV full-range
1749 formats and [16-235] for YUV non full-range formats.
1751 Default value is 0.10.
1754 The following example sets the maximum pixel threshold to the minimum
1755 value, and detects only black intervals of 2 or more seconds:
1757 blackdetect=d=2:pix_th=0.00
1762 Detect frames that are (almost) completely black. Can be useful to
1763 detect chapter transitions or commercials. Output lines consist of
1764 the frame number of the detected frame, the percentage of blackness,
1765 the position in the file if known or -1 and the timestamp in seconds.
1767 In order to display the output lines, you need to set the loglevel at
1768 least to the AV_LOG_INFO value.
1770 The filter accepts the syntax:
1772 blackframe[=@var{amount}:[@var{threshold}]]
1775 @var{amount} is the percentage of the pixels that have to be below the
1776 threshold, and defaults to 98.
1778 @var{threshold} is the threshold below which a pixel value is
1779 considered black, and defaults to 32.
1783 Apply boxblur algorithm to the input video.
1785 This filter accepts the parameters:
1786 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1788 Chroma and alpha parameters are optional, if not specified they default
1789 to the corresponding values set for @var{luma_radius} and
1792 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1793 the radius in pixels of the box used for blurring the corresponding
1794 input plane. They are expressions, and can contain the following
1798 the input width and height in pixels
1801 the input chroma image width and height in pixels
1804 horizontal and vertical chroma subsample values. For example for the
1805 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1808 The radius must be a non-negative number, and must not be greater than
1809 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1810 and of @code{min(cw,ch)/2} for the chroma planes.
1812 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1813 how many times the boxblur filter is applied to the corresponding
1816 Some examples follow:
1821 Apply a boxblur filter with luma, chroma, and alpha radius
1828 Set luma radius to 2, alpha and chroma radius to 0
1834 Set luma and chroma radius to a fraction of the video dimension
1836 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1841 @section colormatrix
1843 The colormatrix filter allows conversion between any of the following color
1844 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1845 and FCC (@var{fcc}).
1847 The syntax of the parameters is @var{source}:@var{destination}:
1850 colormatrix=bt601:smpte240m
1855 Copy the input source unchanged to the output. Mainly useful for
1860 Crop the input video.
1862 This filter accepts a list of @var{key}=@var{value} pairs as argument,
1863 separated by ':'. If the key of the first options is omitted, the
1864 arguments are interpreted according to the syntax
1865 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
1867 A description of the accepted options follows:
1870 Set the crop area width. It defaults to @code{iw}.
1871 This expression is evaluated only once during the filter
1875 Set the crop area width. It defaults to @code{ih}.
1876 This expression is evaluated only once during the filter
1880 Set the expression for the x top-left coordinate of the cropped area.
1881 It defaults to @code{(in_w-out_w)/2}.
1882 This expression is evaluated per-frame.
1885 Set the expression for the y top-left coordinate of the cropped area.
1886 It defaults to @code{(in_h-out_h)/2}.
1887 This expression is evaluated per-frame.
1890 If set to 1 will force the output display aspect ratio
1891 to be the same of the input, by changing the output sample aspect
1892 ratio. It defaults to 0.
1895 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1896 expressions containing the following constants:
1900 the computed values for @var{x} and @var{y}. They are evaluated for
1904 the input width and height
1907 same as @var{in_w} and @var{in_h}
1910 the output (cropped) width and height
1913 same as @var{out_w} and @var{out_h}
1916 same as @var{iw} / @var{ih}
1919 input sample aspect ratio
1922 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1925 horizontal and vertical chroma subsample values. For example for the
1926 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1929 the number of input frame, starting from 0
1932 the position in the file of the input frame, NAN if unknown
1935 timestamp expressed in seconds, NAN if the input timestamp is unknown
1939 The expression for @var{out_w} may depend on the value of @var{out_h},
1940 and the expression for @var{out_h} may depend on @var{out_w}, but they
1941 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1942 evaluated after @var{out_w} and @var{out_h}.
1944 The @var{x} and @var{y} parameters specify the expressions for the
1945 position of the top-left corner of the output (non-cropped) area. They
1946 are evaluated for each frame. If the evaluated value is not valid, it
1947 is approximated to the nearest valid value.
1949 The expression for @var{x} may depend on @var{y}, and the expression
1950 for @var{y} may depend on @var{x}.
1952 @subsection Examples
1955 Crop area with size 100x100 at position (12,34).
1960 Using named options, the example above becomes:
1962 crop=w=100:h=100:x=12:y=34
1966 Crop the central input area with size 100x100:
1972 Crop the central input area with size 2/3 of the input video:
1974 crop=2/3*in_w:2/3*in_h
1978 Crop the input video central square:
1984 Delimit the rectangle with the top-left corner placed at position
1985 100:100 and the right-bottom corner corresponding to the right-bottom
1986 corner of the input image:
1988 crop=in_w-100:in_h-100:100:100
1992 Crop 10 pixels from the left and right borders, and 20 pixels from
1993 the top and bottom borders
1995 crop=in_w-2*10:in_h-2*20
1999 Keep only the bottom right quarter of the input image:
2001 crop=in_w/2:in_h/2:in_w/2:in_h/2
2005 Crop height for getting Greek harmony:
2007 crop=in_w:1/PHI*in_w
2011 Appply trembling effect:
2013 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)
2017 Apply erratic camera effect depending on timestamp:
2019 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)"
2023 Set x depending on the value of y:
2025 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2031 Auto-detect crop size.
2033 Calculate necessary cropping parameters and prints the recommended
2034 parameters through the logging system. The detected dimensions
2035 correspond to the non-black area of the input video.
2037 It accepts the syntax:
2039 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
2045 Threshold, which can be optionally specified from nothing (0) to
2046 everything (255), defaults to 24.
2049 Value which the width/height should be divisible by, defaults to
2050 16. The offset is automatically adjusted to center the video. Use 2 to
2051 get only even dimensions (needed for 4:2:2 video). 16 is best when
2052 encoding to most video codecs.
2055 Counter that determines after how many frames cropdetect will reset
2056 the previously detected largest video area and start over to detect
2057 the current optimal crop area. Defaults to 0.
2059 This can be useful when channel logos distort the video area. 0
2060 indicates never reset and return the largest area encountered during
2066 This filter drops frames that do not differ greatly from the previous
2067 frame in order to reduce framerate. The main use of this filter is
2068 for very-low-bitrate encoding (e.g. streaming over dialup modem), but
2069 it could in theory be used for fixing movies that were
2070 inverse-telecined incorrectly.
2072 It accepts the following parameters:
2073 @var{max}:@var{hi}:@var{lo}:@var{frac}.
2078 Set the maximum number of consecutive frames which can be dropped (if
2079 positive), or the minimum interval between dropped frames (if
2080 negative). If the value is 0, the frame is dropped unregarding the
2081 number of previous sequentially dropped frames.
2086 Set the dropping threshold values.
2088 Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
2089 represent actual pixel value differences, so a threshold of 64
2090 corresponds to 1 unit of difference for each pixel, or the same spread
2091 out differently over the block.
2093 A frame is a candidate for dropping if no 8x8 blocks differ by more
2094 than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
2095 meaning the whole image) differ by more than a threshold of @var{lo}.
2097 Default value for @var{hi} is 64*12, default value for @var{lo} is
2098 64*5, and default value for @var{frac} is 0.33.
2103 Suppress a TV station logo by a simple interpolation of the surrounding
2104 pixels. Just set a rectangle covering the logo and watch it disappear
2105 (and sometimes something even uglier appear - your mileage may vary).
2107 The filter accepts parameters as a string of the form
2108 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
2109 @var{key}=@var{value} pairs, separated by ":".
2111 The description of the accepted parameters follows.
2116 Specify the top left corner coordinates of the logo. They must be
2120 Specify the width and height of the logo to clear. They must be
2124 Specify the thickness of the fuzzy edge of the rectangle (added to
2125 @var{w} and @var{h}). The default value is 4.
2128 When set to 1, a green rectangle is drawn on the screen to simplify
2129 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2130 @var{band} is set to 4. The default value is 0.
2134 Some examples follow.
2139 Set a rectangle covering the area with top left corner coordinates 0,0
2140 and size 100x77, setting a band of size 10:
2142 delogo=0:0:100:77:10
2146 As the previous example, but use named options:
2148 delogo=x=0:y=0:w=100:h=77:band=10
2155 Attempt to fix small changes in horizontal and/or vertical shift. This
2156 filter helps remove camera shake from hand-holding a camera, bumping a
2157 tripod, moving on a vehicle, etc.
2159 The filter accepts parameters as a string of the form
2160 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
2162 A description of the accepted parameters follows.
2167 Specify a rectangular area where to limit the search for motion
2169 If desired the search for motion vectors can be limited to a
2170 rectangular area of the frame defined by its top left corner, width
2171 and height. These parameters have the same meaning as the drawbox
2172 filter which can be used to visualise the position of the bounding
2175 This is useful when simultaneous movement of subjects within the frame
2176 might be confused for camera motion by the motion vector search.
2178 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2179 then the full frame is used. This allows later options to be set
2180 without specifying the bounding box for the motion vector search.
2182 Default - search the whole frame.
2185 Specify the maximum extent of movement in x and y directions in the
2186 range 0-64 pixels. Default 16.
2189 Specify how to generate pixels to fill blanks at the edge of the
2190 frame. An integer from 0 to 3 as follows:
2193 Fill zeroes at blank locations
2195 Original image at blank locations
2197 Extruded edge value at blank locations
2199 Mirrored edge at blank locations
2202 The default setting is mirror edge at blank locations.
2205 Specify the blocksize to use for motion search. Range 4-128 pixels,
2209 Specify the contrast threshold for blocks. Only blocks with more than
2210 the specified contrast (difference between darkest and lightest
2211 pixels) will be considered. Range 1-255, default 125.
2214 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
2215 search. Default - exhaustive search.
2218 If set then a detailed log of the motion search is written to the
2225 Draw a colored box on the input image.
2227 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2230 The description of the accepted parameters follows.
2234 Specify the top left corner coordinates of the box. Default to 0.
2238 Specify the width and height of the box, if 0 they are interpreted as
2239 the input width and height. Default to 0.
2242 Specify the color of the box to write, it can be the name of a color
2243 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2244 value @code{invert} is used, the box edge color is the same as the
2245 video with inverted luma.
2248 Set the thickness of the box edge. Default value is @code{4}.
2251 If the key of the first options is omitted, the arguments are
2252 interpreted according to the syntax
2253 @var{x}:@var{y}:@var{width}:@var{height}:@var{color}:@var{thickness}.
2255 Some examples follow:
2258 Draw a black box around the edge of the input image:
2264 Draw a box with color red and an opacity of 50%:
2266 drawbox=10:20:200:60:red@@0.5
2269 The previous example can be specified as:
2271 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2275 Fill the box with pink color:
2277 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2284 Draw text string or text from specified file on top of video using the
2285 libfreetype library.
2287 To enable compilation of this filter you need to configure FFmpeg with
2288 @code{--enable-libfreetype}.
2292 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2295 The description of the accepted parameters follows.
2300 Used to draw a box around text using background color.
2301 Value should be either 1 (enable) or 0 (disable).
2302 The default value of @var{box} is 0.
2305 The color to be used for drawing box around text.
2306 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2307 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2308 The default value of @var{boxcolor} is "white".
2311 Set an expression which specifies if the text should be drawn. If the
2312 expression evaluates to 0, the text is not drawn. This is useful for
2313 specifying that the text should be drawn only when specific conditions
2316 Default value is "1".
2318 See below for the list of accepted constants and functions.
2321 Select how the @var{text} is expanded. Can be either @code{none},
2322 @code{strftime} (deprecated) or
2323 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2327 If true, check and fix text coords to avoid clipping.
2330 The color to be used for drawing fonts.
2331 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2332 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2333 The default value of @var{fontcolor} is "black".
2336 The font file to be used for drawing text. Path must be included.
2337 This parameter is mandatory.
2340 The font size to be used for drawing text.
2341 The default value of @var{fontsize} is 16.
2344 Flags to be used for loading the fonts.
2346 The flags map the corresponding flags supported by libfreetype, and are
2347 a combination of the following values:
2354 @item vertical_layout
2355 @item force_autohint
2358 @item ignore_global_advance_width
2360 @item ignore_transform
2367 Default value is "render".
2369 For more information consult the documentation for the FT_LOAD_*
2373 The color to be used for drawing a shadow behind the drawn text. It
2374 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2375 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2376 The default value of @var{shadowcolor} is "black".
2378 @item shadowx, shadowy
2379 The x and y offsets for the text shadow position with respect to the
2380 position of the text. They can be either positive or negative
2381 values. Default value for both is "0".
2384 The size in number of spaces to use for rendering the tab.
2388 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2389 format. It can be used with or without text parameter. @var{timecode_rate}
2390 option must be specified.
2392 @item timecode_rate, rate, r
2393 Set the timecode frame rate (timecode only).
2396 The text string to be drawn. The text must be a sequence of UTF-8
2398 This parameter is mandatory if no file is specified with the parameter
2402 A text file containing text to be drawn. The text must be a sequence
2403 of UTF-8 encoded characters.
2405 This parameter is mandatory if no text string is specified with the
2406 parameter @var{text}.
2408 If both @var{text} and @var{textfile} are specified, an error is thrown.
2411 If set to 1, the @var{textfile} will be reloaded before each frame.
2412 Be sure to update it atomically, or it may be read partially, or even fail.
2415 The expressions which specify the offsets where text will be drawn
2416 within the video frame. They are relative to the top/left border of the
2419 The default value of @var{x} and @var{y} is "0".
2421 See below for the list of accepted constants and functions.
2424 The parameters for @var{x} and @var{y} are expressions containing the
2425 following constants and functions:
2429 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2432 horizontal and vertical chroma subsample values. For example for the
2433 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2436 the height of each text line
2444 @item max_glyph_a, ascent
2445 the maximum distance from the baseline to the highest/upper grid
2446 coordinate used to place a glyph outline point, for all the rendered
2448 It is a positive value, due to the grid's orientation with the Y axis
2451 @item max_glyph_d, descent
2452 the maximum distance from the baseline to the lowest grid coordinate
2453 used to place a glyph outline point, for all the rendered glyphs.
2454 This is a negative value, due to the grid's orientation, with the Y axis
2458 maximum glyph height, that is the maximum height for all the glyphs
2459 contained in the rendered text, it is equivalent to @var{ascent} -
2463 maximum glyph width, that is the maximum width for all the glyphs
2464 contained in the rendered text
2467 the number of input frame, starting from 0
2469 @item rand(min, max)
2470 return a random number included between @var{min} and @var{max}
2473 input sample aspect ratio
2476 timestamp expressed in seconds, NAN if the input timestamp is unknown
2479 the height of the rendered text
2482 the width of the rendered text
2485 the x and y offset coordinates where the text is drawn.
2487 These parameters allow the @var{x} and @var{y} expressions to refer
2488 each other, so you can for example specify @code{y=x/dar}.
2491 If libavfilter was built with @code{--enable-fontconfig}, then
2492 @option{fontfile} can be a fontconfig pattern or omitted.
2494 @anchor{drawtext_expansion}
2495 @subsection Text expansion
2497 If @option{expansion} is set to @code{strftime},
2498 the filter recognizes strftime() sequences in the provided text and
2499 expands them accordingly. Check the documentation of strftime(). This
2500 feature is deprecated.
2502 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2504 If @option{expansion} is set to @code{normal} (which is the default),
2505 the following expansion mechanism is used.
2507 The backslash character '\', followed by any character, always expands to
2508 the second character.
2510 Sequence of the form @code{%@{...@}} are expanded. The text between the
2511 braces is a function name, possibly followed by arguments separated by ':'.
2512 If the arguments contain special characters or delimiters (':' or '@}'),
2513 they should be escaped.
2515 Note that they probably must also be escaped as the value for the
2516 @option{text} option in the filter argument string and as the filter
2517 argument in the filter graph description, and possibly also for the shell,
2518 that makes up to four levels of escaping; using a text file avoids these
2521 The following functions are available:
2526 The expression evaluation result.
2528 It must take one argument specifying the expression to be evaluated,
2529 which accepts the same constants and functions as the @var{x} and
2530 @var{y} values. Note that not all constants should be used, for
2531 example the text size is not known when evaluating the expression, so
2532 the constants @var{text_w} and @var{text_h} will have an undefined
2536 The time at which the filter is running, expressed in UTC.
2537 It can accept an argument: a strftime() format string.
2540 The time at which the filter is running, expressed in the local time zone.
2541 It can accept an argument: a strftime() format string.
2544 The frame number, starting from 0.
2547 The timestamp of the current frame, in seconds, with microsecond accuracy.
2551 @subsection Examples
2553 Some examples follow.
2558 Draw "Test Text" with font FreeSerif, using the default values for the
2559 optional parameters.
2562 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2566 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2567 and y=50 (counting from the top-left corner of the screen), text is
2568 yellow with a red box around it. Both the text and the box have an
2572 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2573 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2576 Note that the double quotes are not necessary if spaces are not used
2577 within the parameter list.
2580 Show the text at the center of the video frame:
2582 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2586 Show a text line sliding from right to left in the last row of the video
2587 frame. The file @file{LONG_LINE} is assumed to contain a single line
2590 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2594 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2596 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2600 Draw a single green letter "g", at the center of the input video.
2601 The glyph baseline is placed at half screen height.
2603 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2607 Show text for 1 second every 3 seconds:
2609 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2613 Use fontconfig to set the font. Note that the colons need to be escaped.
2615 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2619 Print the date of a real-time encoding (see strftime(3)):
2621 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2626 For more information about libfreetype, check:
2627 @url{http://www.freetype.org/}.
2629 For more information about fontconfig, check:
2630 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2634 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2636 This filter accepts the following optional named parameters:
2640 Set low and high threshold values used by the Canny thresholding
2643 The high threshold selects the "strong" edge pixels, which are then
2644 connected through 8-connectivity with the "weak" edge pixels selected
2645 by the low threshold.
2647 @var{low} and @var{high} threshold values must be choosen in the range
2648 [0,1], and @var{low} should be lesser or equal to @var{high}.
2650 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2656 edgedetect=low=0.1:high=0.4
2661 Apply fade-in/out effect to input video.
2663 The filter accepts parameters as a list of @var{key}=@var{value}
2664 pairs, separated by ":". If the key of the first options is omitted,
2665 the arguments are interpreted according to the syntax
2666 @var{type}:@var{start_frame}:@var{nb_frames}.
2668 A description of the accepted parameters follows.
2672 Specify if the effect type, can be either @code{in} for fade-in, or
2673 @code{out} for a fade-out effect. Default is @code{in}.
2675 @item start_frame, s
2676 Specify the number of the start frame for starting to apply the fade
2677 effect. Default is 0.
2680 Specify the number of frames for which the fade effect has to last. At
2681 the end of the fade-in effect the output video will have the same
2682 intensity as the input video, at the end of the fade-out transition
2683 the output video will be completely black. Default is 25.
2686 If set to 1, fade only alpha channel, if one exists on the input.
2690 @subsection Examples
2693 Fade in first 30 frames of video:
2698 The command above is equivalent to:
2704 Fade out last 45 frames of a 200-frame video:
2710 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
2712 fade=in:0:25, fade=out:975:25
2716 Make first 5 frames black, then fade in from frame 5-24:
2722 Fade in alpha over first 25 frames of video:
2724 fade=in:0:25:alpha=1
2730 Extract a single field from an interlaced image using stride
2731 arithmetic to avoid wasting CPU time. The output frames are marked as
2734 This filter accepts the following named options:
2737 Specify whether to extract the top (if the value is @code{0} or
2738 @code{top}) or the bottom field (if the value is @code{1} or
2742 If the option key is not specified, the first value sets the @var{type}
2743 option. For example:
2755 Transform the field order of the input video.
2757 It accepts one parameter which specifies the required field order that
2758 the input interlaced video will be transformed to. The parameter can
2759 assume one of the following values:
2763 output bottom field first
2765 output top field first
2768 Default value is "tff".
2770 Transformation is achieved by shifting the picture content up or down
2771 by one line, and filling the remaining line with appropriate picture content.
2772 This method is consistent with most broadcast field order converters.
2774 If the input video is not flagged as being interlaced, or it is already
2775 flagged as being of the required output field order then this filter does
2776 not alter the incoming video.
2778 This filter is very useful when converting to or from PAL DV material,
2779 which is bottom field first.
2783 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2788 Buffer input images and send them when they are requested.
2790 This filter is mainly useful when auto-inserted by the libavfilter
2793 The filter does not take parameters.
2797 Convert the input video to one of the specified pixel formats.
2798 Libavfilter will try to pick one that is supported for the input to
2801 The filter accepts a list of pixel format names, separated by ":",
2802 for example "yuv420p:monow:rgb24".
2804 Some examples follow:
2806 # convert the input video to the format "yuv420p"
2809 # convert the input video to any of the formats in the list
2810 format=yuv420p:yuv444p:yuv410p
2815 Convert the video to specified constant framerate by duplicating or dropping
2816 frames as necessary.
2818 This filter accepts the following named parameters:
2822 Desired output framerate. The default is @code{25}.
2827 Possible values are:
2830 zero round towards 0
2834 round towards -infinity
2836 round towards +infinity
2840 The default is @code{near}.
2844 Alternatively, the options can be specified as a flat string:
2845 @var{fps}[:@var{round}].
2847 See also the @ref{setpts} filter.
2851 Select one frame every N.
2853 This filter accepts in input a string representing a positive
2854 integer. Default argument is @code{1}.
2859 Apply a frei0r effect to the input video.
2861 To enable compilation of this filter you need to install the frei0r
2862 header and configure FFmpeg with @code{--enable-frei0r}.
2864 The filter supports the syntax:
2866 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2869 @var{filter_name} is the name of the frei0r effect to load. If the
2870 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2871 is searched in each one of the directories specified by the colon (or
2872 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2873 otherwise in the standard frei0r paths, which are in this order:
2874 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2875 @file{/usr/lib/frei0r-1/}.
2877 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2878 for the frei0r effect.
2880 A frei0r effect parameter can be a boolean (whose values are specified
2881 with "y" and "n"), a double, a color (specified by the syntax
2882 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2883 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2884 description), a position (specified by the syntax @var{X}/@var{Y},
2885 @var{X} and @var{Y} being float numbers) and a string.
2887 The number and kind of parameters depend on the loaded effect. If an
2888 effect parameter is not specified the default value is set.
2890 Some examples follow:
2894 Apply the distort0r effect, set the first two double parameters:
2896 frei0r=distort0r:0.5:0.01
2900 Apply the colordistance effect, take a color as first parameter:
2902 frei0r=colordistance:0.2/0.3/0.4
2903 frei0r=colordistance:violet
2904 frei0r=colordistance:0x112233
2908 Apply the perspective effect, specify the top left and top right image
2911 frei0r=perspective:0.2/0.2:0.8/0.2
2915 For more information see:
2916 @url{http://frei0r.dyne.org}
2920 The filter takes one, two or three equations as parameter, separated by ':'.
2921 The first equation is mandatory and applies to the luma plane. The two
2922 following are respectively for chroma blue and chroma red planes.
2924 The filter syntax allows named parameters:
2928 the luminance expression
2930 the chrominance blue expression
2932 the chrominance red expression
2935 If one of the chrominance expression is not defined, it falls back on the other
2936 one. If none of them are specified, they will evaluate the luminance
2939 The expressions can use the following variables and functions:
2943 The sequential number of the filtered frame, starting from @code{0}.
2946 The coordinates of the current sample.
2949 The width and height of the image.
2952 Width and height scale depending on the currently filtered plane. It is the
2953 ratio between the corresponding luma plane number of pixels and the current
2954 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2955 @code{0.5,0.5} for chroma planes.
2958 Time of the current frame, expressed in seconds.
2961 Return the value of the pixel at location (@var{x},@var{y}) of the current
2965 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
2969 Return the value of the pixel at location (@var{x},@var{y}) of the
2970 blue-difference chroma plane.
2973 Return the value of the pixel at location (@var{x},@var{y}) of the
2974 red-difference chroma plane.
2977 For functions, if @var{x} and @var{y} are outside the area, the value will be
2978 automatically clipped to the closer edge.
2980 Some examples follow:
2984 Flip the image horizontally:
2990 Generate a bidimensional sine wave, with angle @code{PI/3} and a
2991 wavelength of 100 pixels:
2993 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
2997 Generate a fancy enigmatic moving light:
2999 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
3005 Fix the banding artifacts that are sometimes introduced into nearly flat
3006 regions by truncation to 8bit color depth.
3007 Interpolate the gradients that should go where the bands are, and
3010 This filter is designed for playback only. Do not use it prior to
3011 lossy compression, because compression tends to lose the dither and
3012 bring back the bands.
3014 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
3015 separated by ":". A description of the accepted options follows.
3020 The maximum amount by which the filter will change
3021 any one pixel. Also the threshold for detecting nearly flat
3022 regions. Acceptable values range from @code{0.51} to @code{64}, default value
3026 The neighborhood to fit the gradient to. A larger
3027 radius makes for smoother gradients, but also prevents the filter from
3028 modifying the pixels near detailed regions. Acceptable values are
3029 @code{8-32}, default value is @code{16}.
3033 Alternatively, the options can be specified as a flat string:
3034 @var{strength}[:@var{radius}]
3036 @subsection Examples
3040 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3046 Specify radius, omitting the strength (which will fall-back to the default
3056 Flip the input video horizontally.
3058 For example to horizontally flip the input video with @command{ffmpeg}:
3060 ffmpeg -i in.avi -vf "hflip" out.avi
3064 This filter applies a global color histogram equalization on a
3067 It can be used to correct video that has a compressed range of pixel
3068 intensities. The filter redistributes the pixel intensities to
3069 equalize their distribution across the intensity range. It may be
3070 viewed as an "automatically adjusting contrast filter". This filter is
3071 useful only for correcting degraded or poorly captured source
3074 The filter accepts parameters as a list of @var{key}=@var{value}
3075 pairs, separated by ":". If the key of the first options is omitted,
3076 the arguments are interpreted according to syntax
3077 @var{strength}:@var{intensity}:@var{antibanding}.
3079 This filter accepts the following named options:
3083 Determine the amount of equalization to be applied. As the strength
3084 is reduced, the distribution of pixel intensities more-and-more
3085 approaches that of the input frame. The value must be a float number
3086 in the range [0,1] and defaults to 0.200.
3089 Set the maximum intensity that can generated and scale the output
3090 values appropriately. The strength should be set as desired and then
3091 the intensity can be limited if needed to avoid washing-out. The value
3092 must be a float number in the range [0,1] and defaults to 0.210.
3095 Set the antibanding level. If enabled the filter will randomly vary
3096 the luminance of output pixels by a small amount to avoid banding of
3097 the histogram. Possible values are @code{none}, @code{weak} or
3098 @code{strong}. It defaults to @code{none}.
3103 Compute and draw a color distribution histogram for the input video.
3105 The computed histogram is a representation of distribution of color components
3108 The filter accepts the following named parameters:
3114 It accepts the following values:
3117 standard histogram that display color components distribution in an image.
3118 Displays color graph for each color component. Shows distribution
3119 of the Y, U, V, A or G, B, R components, depending on input format,
3120 in current frame. Bellow each graph is color component scale meter.
3123 chroma values in vectorscope, if brighter more such chroma values are
3124 distributed in an image.
3125 Displays chroma values (U/V color placement) in two dimensional graph
3126 (which is called a vectorscope). It can be used to read of the hue and
3127 saturation of the current frame. At a same time it is a histogram.
3128 The whiter a pixel in the vectorscope, the more pixels of the input frame
3129 correspond to that pixel (that is the more pixels have this chroma value).
3130 The V component is displayed on the horizontal (X) axis, with the leftmost
3131 side being V = 0 and the rightmost side being V = 255.
3132 The U component is displayed on the vertical (Y) axis, with the top
3133 representing U = 0 and the bottom representing U = 255.
3135 The position of a white pixel in the graph corresponds to the chroma value
3136 of a pixel of the input clip. So the graph can be used to read of the
3137 hue (color flavor) and the saturation (the dominance of the hue in the color).
3138 As the hue of a color changes, it moves around the square. At the center of
3139 the square, the saturation is zero, which means that the corresponding pixel
3140 has no color. If you increase the amount of a specific color, while leaving
3141 the other colors unchanged, the saturation increases, and you move towards
3142 the edge of the square.
3145 chroma values in vectorscope, similar as @code{color} but actual chroma values
3149 per row/column luminance graph. In row mode the left side represents luma = 0
3150 and right side represents luma = 255. In column mode top side represends
3151 luma = 0 and bottom side represents luma = 255.
3153 Default value is @code{levels}.
3156 Set height of level in @code{levels}. Default value is @code{200}.
3157 Allowed range is [50, 2048].
3160 Set height of color scale in @code{levels}. Default value is @code{12}.
3161 Allowed range is [0, 40].
3164 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3165 of same luminance values across input rows/columns are distributed.
3166 Default value is @code{10}. Allowed range is [1, 255].
3169 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3170 Default is @code{row}.
3172 @subsection Examples
3177 Calculate and draw histogram:
3179 ffplay -i input -vf histogram
3186 High precision/quality 3d denoise filter. This filter aims to reduce
3187 image noise producing smooth images and making still images really
3188 still. It should enhance compressibility.
3190 It accepts the following optional parameters:
3191 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3195 a non-negative float number which specifies spatial luma strength,
3198 @item chroma_spatial
3199 a non-negative float number which specifies spatial chroma strength,
3200 defaults to 3.0*@var{luma_spatial}/4.0
3203 a float number which specifies luma temporal strength, defaults to
3204 6.0*@var{luma_spatial}/4.0
3207 a float number which specifies chroma temporal strength, defaults to
3208 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3213 Modify the hue and/or the saturation of the input.
3215 This filter accepts the following optional named options:
3219 Specify the hue angle as a number of degrees. It accepts a float
3220 number or an expression, and defaults to 0.0.
3223 Specify the hue angle as a number of degrees. It accepts a float
3224 number or an expression, and defaults to 0.0.
3227 Specify the saturation in the [-10,10] range. It accepts a float number and
3231 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3232 following constants:
3236 frame count of the input frame starting from 0
3239 presentation timestamp of the input frame expressed in time base units
3242 frame rate of the input video, NAN if the input frame rate is unknown
3245 timestamp expressed in seconds, NAN if the input timestamp is unknown
3248 time base of the input video
3251 The options can also be set using the syntax: @var{hue}:@var{saturation}
3253 In this case @var{hue} is expressed in degrees.
3255 Some examples follow:
3258 Set the hue to 90 degrees and the saturation to 1.0:
3264 Same command but expressing the hue in radians:
3270 Same command without named options, hue must be expressed in degrees:
3276 Note that "h:s" syntax does not support expressions for the values of
3277 h and s, so the following example will issue an error:
3283 Rotate hue and make the saturation swing between 0
3284 and 2 over a period of 1 second:
3286 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3290 Apply a 3 seconds saturation fade-in effect starting at 0:
3295 The general fade-in expression can be written as:
3297 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3301 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3303 hue="s=max(0\, min(1\, (8-t)/3))"
3306 The general fade-out expression can be written as:
3308 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3313 @subsection Commands
3315 This filter supports the following command:
3318 Modify the hue and/or the saturation of the input video.
3319 The command accepts the same named options and syntax than when calling the
3320 filter from the command-line.
3322 If a parameter is omitted, it is kept at its current value.
3327 Interlaceing detect filter. This filter tries to detect if the input is
3328 interlaced or progressive. Top or bottom field first.
3332 Deinterlace input video by applying Donald Graft's adaptive kernel
3333 deinterling. Work on interlaced parts of a video to produce
3336 This filter accepts parameters as a list of @var{key}=@var{value}
3337 pairs, separated by ":". If the key of the first options is omitted,
3338 the arguments are interpreted according to the following syntax:
3339 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3341 The description of the accepted parameters follows.
3345 Set the threshold which affects the filter's tolerance when
3346 determining if a pixel line must be processed. It must be an integer
3347 in the range [0,255] and defaults to 10. A value of 0 will result in
3348 applying the process on every pixels.
3351 Paint pixels exceeding the threshold value to white if set to 1.
3355 Set the fields order. Swap fields if set to 1, leave fields alone if
3359 Enable additional sharpening if set to 1. Default is 0.
3362 Enable twoway sharpening if set to 1. Default is 0.
3365 @subsection Examples
3369 Apply default values:
3371 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3375 Enable additional sharpening:
3381 Paint processed pixels in white:
3387 @section lut, lutrgb, lutyuv
3389 Compute a look-up table for binding each pixel component input value
3390 to an output value, and apply it to input video.
3392 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3393 to an RGB input video.
3395 These filters accept in input a ":"-separated list of options, which
3396 specify the expressions used for computing the lookup table for the
3397 corresponding pixel component values.
3399 The @var{lut} filter requires either YUV or RGB pixel formats in
3400 input, and accepts the options:
3403 set first pixel component expression
3405 set second pixel component expression
3407 set third pixel component expression
3409 set fourth pixel component expression, corresponds to the alpha component
3412 The exact component associated to each option depends on the format in
3415 The @var{lutrgb} filter requires RGB pixel formats in input, and
3416 accepts the options:
3419 set red component expression
3421 set green component expression
3423 set blue component expression
3425 alpha component expression
3428 The @var{lutyuv} filter requires YUV pixel formats in input, and
3429 accepts the options:
3432 set Y/luminance component expression
3434 set U/Cb component expression
3436 set V/Cr component expression
3438 set alpha component expression
3441 The expressions can contain the following constants and functions:
3445 the input width and height
3448 input value for the pixel component
3451 the input value clipped in the @var{minval}-@var{maxval} range
3454 maximum value for the pixel component
3457 minimum value for the pixel component
3460 the negated value for the pixel component value clipped in the
3461 @var{minval}-@var{maxval} range , it corresponds to the expression
3462 "maxval-clipval+minval"
3465 the computed value in @var{val} clipped in the
3466 @var{minval}-@var{maxval} range
3468 @item gammaval(gamma)
3469 the computed gamma correction value of the pixel component value
3470 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3472 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3476 All expressions default to "val".
3478 @subsection Examples
3484 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3485 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3488 The above is the same as:
3490 lutrgb="r=negval:g=negval:b=negval"
3491 lutyuv="y=negval:u=negval:v=negval"
3501 Remove chroma components, turns the video into a graytone image:
3503 lutyuv="u=128:v=128"
3507 Apply a luma burning effect:
3513 Remove green and blue components:
3519 Set a constant alpha channel value on input:
3521 format=rgba,lutrgb=a="maxval-minval/2"
3525 Correct luminance gamma by a 0.5 factor:
3527 lutyuv=y=gammaval(0.5)
3533 Apply an MPlayer filter to the input video.
3535 This filter provides a wrapper around most of the filters of
3538 This wrapper is considered experimental. Some of the wrapped filters
3539 may not work properly and we may drop support for them, as they will
3540 be implemented natively into FFmpeg. Thus you should avoid
3541 depending on them when writing portable scripts.
3543 The filters accepts the parameters:
3544 @var{filter_name}[:=]@var{filter_params}
3546 @var{filter_name} is the name of a supported MPlayer filter,
3547 @var{filter_params} is a string containing the parameters accepted by
3550 The list of the currently supported filters follows:
3584 The parameter syntax and behavior for the listed filters are the same
3585 of the corresponding MPlayer filters. For detailed instructions check
3586 the "VIDEO FILTERS" section in the MPlayer manual.
3588 Some examples follow:
3591 Adjust gamma, brightness, contrast:
3597 Add temporal noise to input video:
3603 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3609 This filter accepts an integer in input, if non-zero it negates the
3610 alpha component (if available). The default value in input is 0.
3614 Force libavfilter not to use any of the specified pixel formats for the
3615 input to the next filter.
3617 The filter accepts a list of pixel format names, separated by ":",
3618 for example "yuv420p:monow:rgb24".
3620 Some examples follow:
3622 # force libavfilter to use a format different from "yuv420p" for the
3623 # input to the vflip filter
3624 noformat=yuv420p,vflip
3626 # convert the input video to any of the formats not contained in the list
3627 noformat=yuv420p:yuv444p:yuv410p
3632 Pass the video source unchanged to the output.
3636 Apply video transform using libopencv.
3638 To enable this filter install libopencv library and headers and
3639 configure FFmpeg with @code{--enable-libopencv}.
3641 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3643 @var{filter_name} is the name of the libopencv filter to apply.
3645 @var{filter_params} specifies the parameters to pass to the libopencv
3646 filter. If not specified the default values are assumed.
3648 Refer to the official libopencv documentation for more precise
3650 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3652 Follows the list of supported libopencv filters.
3657 Dilate an image by using a specific structuring element.
3658 This filter corresponds to the libopencv function @code{cvDilate}.
3660 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3662 @var{struct_el} represents a structuring element, and has the syntax:
3663 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3665 @var{cols} and @var{rows} represent the number of columns and rows of
3666 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3667 point, and @var{shape} the shape for the structuring element, and
3668 can be one of the values "rect", "cross", "ellipse", "custom".
3670 If the value for @var{shape} is "custom", it must be followed by a
3671 string of the form "=@var{filename}". The file with name
3672 @var{filename} is assumed to represent a binary image, with each
3673 printable character corresponding to a bright pixel. When a custom
3674 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3675 or columns and rows of the read file are assumed instead.
3677 The default value for @var{struct_el} is "3x3+0x0/rect".
3679 @var{nb_iterations} specifies the number of times the transform is
3680 applied to the image, and defaults to 1.
3682 Follow some example:
3684 # use the default values
3687 # dilate using a structuring element with a 5x5 cross, iterate two times
3688 ocv=dilate=5x5+2x2/cross:2
3690 # read the shape from the file diamond.shape, iterate two times
3691 # the file diamond.shape may contain a pattern of characters like this:
3697 # the specified cols and rows are ignored (but not the anchor point coordinates)
3698 ocv=0x0+2x2/custom=diamond.shape:2
3703 Erode an image by using a specific structuring element.
3704 This filter corresponds to the libopencv function @code{cvErode}.
3706 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3707 with the same syntax and semantics as the @ref{dilate} filter.
3711 Smooth the input video.
3713 The filter takes the following parameters:
3714 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3716 @var{type} is the type of smooth filter to apply, and can be one of
3717 the following values: "blur", "blur_no_scale", "median", "gaussian",
3718 "bilateral". The default value is "gaussian".
3720 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3721 parameters whose meanings depend on smooth type. @var{param1} and
3722 @var{param2} accept integer positive values or 0, @var{param3} and
3723 @var{param4} accept float values.
3725 The default value for @var{param1} is 3, the default value for the
3726 other parameters is 0.
3728 These parameters correspond to the parameters assigned to the
3729 libopencv function @code{cvSmooth}.
3734 Overlay one video on top of another.
3736 It takes two inputs and one output, the first input is the "main"
3737 video on which the second input is overlayed.
3739 This filter accepts a list of @var{key}=@var{value} pairs as argument,
3740 separated by ":". If the key of the first options is omitted, the
3741 arguments are interpreted according to the syntax @var{x}:@var{y}.
3743 A description of the accepted options follows.
3747 Set the expression for the x and y coordinates of the overlayed video
3748 on the main video. Default value is 0.
3750 The @var{x} and @var{y} expressions can contain the following
3753 @item main_w, main_h
3754 main input width and height
3757 same as @var{main_w} and @var{main_h}
3759 @item overlay_w, overlay_h
3760 overlay input width and height
3763 same as @var{overlay_w} and @var{overlay_h}
3767 If set to 1, force the filter to accept inputs in the RGB
3768 color space. Default value is 0.
3771 Be aware that frames are taken from each input video in timestamp
3772 order, hence, if their initial timestamps differ, it is a a good idea
3773 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
3774 have them begin in the same zero timestamp, as it does the example for
3775 the @var{movie} filter.
3777 You can chain together more overlays but you should test the
3778 efficiency of such approach.
3780 @subsection Examples
3784 Draw the overlay at 10 pixels from the bottom right corner of the main
3787 overlay=main_w-overlay_w-10:main_h-overlay_h-10
3790 Using named options the example above becomes:
3792 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
3796 Insert a transparent PNG logo in the bottom left corner of the input,
3797 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
3799 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
3803 Insert 2 different transparent PNG logos (second logo on bottom
3804 right corner) using the @command{ffmpeg} tool:
3806 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
3810 Add a transparent color layer on top of the main video, WxH specifies
3811 the size of the main input to the overlay filter:
3813 color=red@@.3:WxH [over]; [in][over] overlay [out]
3817 Play an original video and a filtered version (here with the deshake
3818 filter) side by side using the @command{ffplay} tool:
3820 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3823 The above command is the same as:
3825 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3829 Chain several overlays in cascade:
3831 nullsrc=s=200x200 [bg];
3832 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
3833 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
3834 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
3835 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
3836 [in3] null, [mid2] overlay=100:100 [out0]
3843 Add paddings to the input image, and place the original input at the
3844 given coordinates @var{x}, @var{y}.
3846 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
3849 If the key of the first options is omitted, the arguments are
3850 interpreted according to the syntax
3851 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3853 A description of the accepted options follows.
3858 Specify an expression for the size of the output image with the
3859 paddings added. If the value for @var{width} or @var{height} is 0, the
3860 corresponding input size is used for the output.
3862 The @var{width} expression can reference the value set by the
3863 @var{height} expression, and vice versa.
3865 The default value of @var{width} and @var{height} is 0.
3869 Specify an expression for the offsets where to place the input image
3870 in the padded area with respect to the top/left border of the output
3873 The @var{x} expression can reference the value set by the @var{y}
3874 expression, and vice versa.
3876 The default value of @var{x} and @var{y} is 0.
3879 Specify the color of the padded area, it can be the name of a color
3880 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3882 The default value of @var{color} is "black".
3885 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
3886 options are expressions containing the following constants:
3890 the input video width and height
3893 same as @var{in_w} and @var{in_h}
3896 the output width and height, that is the size of the padded area as
3897 specified by the @var{width} and @var{height} expressions
3900 same as @var{out_w} and @var{out_h}
3903 x and y offsets as specified by the @var{x} and @var{y}
3904 expressions, or NAN if not yet specified
3907 same as @var{iw} / @var{ih}
3910 input sample aspect ratio
3913 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3916 horizontal and vertical chroma subsample values. For example for the
3917 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3920 @subsection Examples
3924 Add paddings with color "violet" to the input video. Output video
3925 size is 640x480, the top-left corner of the input video is placed at
3928 pad=640:480:0:40:violet
3931 The example above is equivalent to the following command:
3933 pad=width=640:height=480:x=0:y=40:color=violet
3937 Pad the input to get an output with dimensions increased by 3/2,
3938 and put the input video at the center of the padded area:
3940 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
3944 Pad the input to get a squared output with size equal to the maximum
3945 value between the input width and height, and put the input video at
3946 the center of the padded area:
3948 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
3952 Pad the input to get a final w/h ratio of 16:9:
3954 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
3958 In case of anamorphic video, in order to set the output display aspect
3959 correctly, it is necessary to use @var{sar} in the expression,
3960 according to the relation:
3962 (ih * X / ih) * sar = output_dar
3963 X = output_dar / sar
3966 Thus the previous example needs to be modified to:
3968 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
3972 Double output size and put the input video in the bottom-right
3973 corner of the output padded area:
3975 pad="2*iw:2*ih:ow-iw:oh-ih"
3979 @section pixdesctest
3981 Pixel format descriptor test filter, mainly useful for internal
3982 testing. The output video should be equal to the input video.
3986 format=monow, pixdesctest
3989 can be used to test the monowhite pixel format descriptor definition.
3993 Enable the specified chain of postprocessing subfilters using libpostproc. This
3994 library should be automatically selected with a GPL build (@code{--enable-gpl}).
3995 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
3996 Each subfilter and some options have a short and a long name that can be used
3997 interchangeably, i.e. dr/dering are the same.
3999 All subfilters share common options to determine their scope:
4003 Honor the quality commands for this subfilter.
4006 Do chrominance filtering, too (default).
4009 Do luminance filtering only (no chrominance).
4012 Do chrominance filtering only (no luminance).
4015 These options can be appended after the subfilter name, separated by a ':'.
4017 Available subfilters are:
4020 @item hb/hdeblock[:difference[:flatness]]
4021 Horizontal deblocking filter
4024 Difference factor where higher values mean more deblocking (default: @code{32}).
4026 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4029 @item vb/vdeblock[:difference[:flatness]]
4030 Vertical deblocking filter
4033 Difference factor where higher values mean more deblocking (default: @code{32}).
4035 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4038 @item ha/hadeblock[:difference[:flatness]]
4039 Accurate horizontal deblocking filter
4042 Difference factor where higher values mean more deblocking (default: @code{32}).
4044 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4047 @item va/vadeblock[:difference[:flatness]]
4048 Accurate vertical deblocking filter
4051 Difference factor where higher values mean more deblocking (default: @code{32}).
4053 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4057 The horizontal and vertical deblocking filters share the difference and
4058 flatness values so you cannot set different horizontal and vertical
4063 Experimental horizontal deblocking filter
4066 Experimental vertical deblocking filter
4071 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
4074 larger -> stronger filtering
4076 larger -> stronger filtering
4078 larger -> stronger filtering
4081 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4084 Stretch luminance to @code{0-255}.
4087 @item lb/linblenddeint
4088 Linear blend deinterlacing filter that deinterlaces the given block by
4089 filtering all lines with a @code{(1 2 1)} filter.
4091 @item li/linipoldeint
4092 Linear interpolating deinterlacing filter that deinterlaces the given block by
4093 linearly interpolating every second line.
4095 @item ci/cubicipoldeint
4096 Cubic interpolating deinterlacing filter deinterlaces the given block by
4097 cubically interpolating every second line.
4099 @item md/mediandeint
4100 Median deinterlacing filter that deinterlaces the given block by applying a
4101 median filter to every second line.
4103 @item fd/ffmpegdeint
4104 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4105 second line with a @code{(-1 4 2 4 -1)} filter.
4108 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4109 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4111 @item fq/forceQuant[:quantizer]
4112 Overrides the quantizer table from the input with the constant quantizer you
4120 Default pp filter combination (@code{hb:a,vb:a,dr:a})
4123 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
4126 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
4129 @subsection Examples
4133 Apply horizontal and vertical deblocking, deringing and automatic
4134 brightness/contrast:
4140 Apply default filters without brightness/contrast correction:
4146 Apply default filters and temporal denoiser:
4148 pp=default/tmpnoise:1:2:3
4152 Apply deblocking on luminance only, and switch vertical deblocking on or off
4153 automatically depending on available CPU time:
4161 Suppress a TV station logo, using an image file to determine which
4162 pixels comprise the logo. It works by filling in the pixels that
4163 comprise the logo with neighboring pixels.
4165 This filter requires one argument which specifies the filter bitmap
4166 file, which can be any image format supported by libavformat. The
4167 width and height of the image file must match those of the video
4168 stream being processed.
4170 Pixels in the provided bitmap image with a value of zero are not
4171 considered part of the logo, non-zero pixels are considered part of
4172 the logo. If you use white (255) for the logo and black (0) for the
4173 rest, you will be safe. For making the filter bitmap, it is
4174 recommended to take a screen capture of a black frame with the logo
4175 visible, and then using a threshold filter followed by the erode
4176 filter once or twice.
4178 If needed, little splotches can be fixed manually. Remember that if
4179 logo pixels are not covered, the filter quality will be much
4180 reduced. Marking too many pixels as part of the logo does not hurt as
4181 much, but it will increase the amount of blurring needed to cover over
4182 the image and will destroy more information than necessary, and extra
4183 pixels will slow things down on a large logo.
4187 Scale (resize) the input video, using the libswscale library.
4189 The scale filter forces the output display aspect ratio to be the same
4190 of the input, by changing the output sample aspect ratio.
4192 This filter accepts a list of named options in the form of
4193 @var{key}=@var{value} pairs separated by ":". If the key for the first
4194 two options is not specified, the assumed keys for the first two
4195 values are @code{w} and @code{h}. If the first option has no key and
4196 can be interpreted like a video size specification, it will be used
4197 to set the video size.
4199 A description of the accepted options follows.
4203 Set the video width expression, default value is @code{iw}. See below
4204 for the list of accepted constants.
4207 Set the video heiht expression, default value is @code{ih}.
4208 See below for the list of accepted constants.
4211 Set the interlacing. It accepts the following values:
4215 force interlaced aware scaling
4218 do not apply interlaced scaling
4221 select interlaced aware scaling depending on whether the source frames
4222 are flagged as interlaced or not
4225 Default value is @code{0}.
4228 Set libswscale scaling flags. If not explictly specified the filter
4229 applies a bilinear scaling algorithm.
4232 Set the video size, the value must be a valid abbreviation or in the
4233 form @var{width}x@var{height}.
4236 The values of the @var{w} and @var{h} options are expressions
4237 containing the following constants:
4241 the input width and height
4244 same as @var{in_w} and @var{in_h}
4247 the output (cropped) width and height
4250 same as @var{out_w} and @var{out_h}
4253 same as @var{iw} / @var{ih}
4256 input sample aspect ratio
4259 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4262 horizontal and vertical chroma subsample values. For example for the
4263 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4266 If the input image format is different from the format requested by
4267 the next filter, the scale filter will convert the input to the
4270 If the value for @var{width} or @var{height} is 0, the respective input
4271 size is used for the output.
4273 If the value for @var{width} or @var{height} is -1, the scale filter will
4274 use, for the respective output size, a value that maintains the aspect
4275 ratio of the input image.
4277 @subsection Examples
4281 Scale the input video to a size of 200x100:
4286 This is equivalent to:
4297 Specify a size abbreviation for the output size:
4302 which can also be written as:
4308 Scale the input to 2x:
4314 The above is the same as:
4320 Scale the input to 2x with forced interlaced scaling:
4322 scale=2*iw:2*ih:interl=1
4326 Scale the input to half size:
4332 Increase the width, and set the height to the same size:
4338 Seek for Greek harmony:
4345 Increase the height, and set the width to 3/2 of the height:
4351 Increase the size, but make the size a multiple of the chroma:
4353 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4357 Increase the width to a maximum of 500 pixels, keep the same input
4360 scale='min(500\, iw*3/2):-1'
4364 @section setdar, setsar
4366 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4369 This is done by changing the specified Sample (aka Pixel) Aspect
4370 Ratio, according to the following equation:
4372 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4375 Keep in mind that the @code{setdar} filter does not modify the pixel
4376 dimensions of the video frame. Also the display aspect ratio set by
4377 this filter may be changed by later filters in the filterchain,
4378 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4381 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4382 the filter output video.
4384 Note that as a consequence of the application of this filter, the
4385 output display aspect ratio will change according to the equation
4388 Keep in mind that the sample aspect ratio set by the @code{setsar}
4389 filter may be changed by later filters in the filterchain, e.g. if
4390 another "setsar" or a "setdar" filter is applied.
4392 The @code{setdar} and @code{setsar} filters accept a string in the
4393 form @var{num}:@var{den} expressing an aspect ratio, or the following
4394 named options, expressed as a sequence of @var{key}=@var{value} pairs,
4399 Set the maximum integer value to use for expressing numerator and
4400 denominator when reducing the expressed aspect ratio to a rational.
4401 Default value is @code{100}.
4404 Set the aspect ratio used by the filter.
4406 The parameter can be a floating point number string, an expression, or
4407 a string of the form @var{num}:@var{den}, where @var{num} and
4408 @var{den} are the numerator and denominator of the aspect ratio. If
4409 the parameter is not specified, it is assumed the value "0".
4410 In case the form "@var{num}:@var{den}" the @code{:} character should
4414 If the keys are omitted in the named options list, the specifed values
4415 are assumed to be @var{ratio} and @var{max} in that order.
4417 For example to change the display aspect ratio to 16:9, specify:
4422 The example above is equivalent to:
4427 To change the sample aspect ratio to 10:11, specify:
4432 To set a display aspect ratio of 16:9, and specify a maximum integer value of
4433 1000 in the aspect ratio reduction, use the command:
4435 setdar=ratio='16:9':max=1000
4440 Force field for the output video frame.
4442 The @code{setfield} filter marks the interlace type field for the
4443 output frames. It does not change the input frame, but only sets the
4444 corresponding property, which affects how the frame is treated by
4445 following filters (e.g. @code{fieldorder} or @code{yadif}).
4447 This filter accepts a single option @option{mode}, which can be
4448 specified either by setting @code{mode=VALUE} or setting the value
4449 alone. Available values are:
4453 Keep the same field property.
4456 Mark the frame as bottom-field-first.
4459 Mark the frame as top-field-first.
4462 Mark the frame as progressive.
4467 Show a line containing various information for each input video frame.
4468 The input video is not modified.
4470 The shown line contains a sequence of key/value pairs of the form
4471 @var{key}:@var{value}.
4473 A description of each shown parameter follows:
4477 sequential number of the input frame, starting from 0
4480 Presentation TimeStamp of the input frame, expressed as a number of
4481 time base units. The time base unit depends on the filter input pad.
4484 Presentation TimeStamp of the input frame, expressed as a number of
4488 position of the frame in the input stream, -1 if this information in
4489 unavailable and/or meaningless (for example in case of synthetic video)
4495 sample aspect ratio of the input frame, expressed in the form
4499 size of the input frame, expressed in the form
4500 @var{width}x@var{height}
4503 interlaced mode ("P" for "progressive", "T" for top field first, "B"
4504 for bottom field first)
4507 1 if the frame is a key frame, 0 otherwise
4510 picture type of the input frame ("I" for an I-frame, "P" for a
4511 P-frame, "B" for a B-frame, "?" for unknown type).
4512 Check also the documentation of the @code{AVPictureType} enum and of
4513 the @code{av_get_picture_type_char} function defined in
4514 @file{libavutil/avutil.h}.
4517 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
4519 @item plane_checksum
4520 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
4521 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
4526 Blur the input video without impacting the outlines.
4528 The filter accepts the following parameters:
4529 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
4531 Parameters prefixed by @var{luma} indicate that they work on the
4532 luminance of the pixels whereas parameters prefixed by @var{chroma}
4533 refer to the chrominance of the pixels.
4535 If the chroma parameters are not set, the luma parameters are used for
4536 either the luminance and the chrominance of the pixels.
4538 @var{luma_radius} or @var{chroma_radius} must be a float number in the
4539 range [0.1,5.0] that specifies the variance of the gaussian filter
4540 used to blur the image (slower if larger).
4542 @var{luma_strength} or @var{chroma_strength} must be a float number in
4543 the range [-1.0,1.0] that configures the blurring. A value included in
4544 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
4545 will sharpen the image.
4547 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
4548 the range [-30,30] that is used as a coefficient to determine whether
4549 a pixel should be blurred or not. A value of 0 will filter all the
4550 image, a value included in [0,30] will filter flat areas and a value
4551 included in [-30,0] will filter edges.
4556 Draw subtitles on top of input video using the libass library.
4558 To enable compilation of this filter you need to configure FFmpeg with
4559 @code{--enable-libass}. This filter also requires a build with libavcodec and
4560 libavformat to convert the passed subtitles file to ASS (Advanced Substation
4561 Alpha) subtitles format.
4563 This filter accepts the following named options, expressed as a
4564 sequence of @var{key}=@var{value} pairs, separated by ":".
4568 Set the filename of the subtitle file to read. It must be specified.
4571 Specify the size of the original video, the video for which the ASS file
4572 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
4573 necessary to correctly scale the fonts if the aspect ratio has been changed.
4576 If the first key is not specified, it is assumed that the first value
4577 specifies the @option{filename}.
4579 For example, to render the file @file{sub.srt} on top of the input
4580 video, use the command:
4585 which is equivalent to:
4587 subtitles=filename=sub.srt
4592 Split input video into several identical outputs.
4594 The filter accepts a single parameter which specifies the number of outputs. If
4595 unspecified, it defaults to 2.
4599 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
4601 will create 5 copies of the input video.
4605 [in] split [splitout1][splitout2];
4606 [splitout1] crop=100:100:0:0 [cropout];
4607 [splitout2] pad=200:200:100:100 [padout];
4610 will create two separate outputs from the same input, one cropped and
4615 Scale the input by 2x and smooth using the Super2xSaI (Scale and
4616 Interpolate) pixel art scaling algorithm.
4618 Useful for enlarging pixel art images without reducing sharpness.
4624 Select the most representative frame in a given sequence of consecutive frames.
4626 It accepts as argument the frames batch size to analyze (default @var{N}=100);
4627 in a set of @var{N} frames, the filter will pick one of them, and then handle
4628 the next batch of @var{N} frames until the end.
4630 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
4631 value will result in a higher memory usage, so a high value is not recommended.
4633 The following example extract one picture each 50 frames:
4638 Complete example of a thumbnail creation with @command{ffmpeg}:
4640 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
4645 Tile several successive frames together.
4647 It accepts a list of options in the form of @var{key}=@var{value} pairs
4648 separated by ":". A description of the accepted options follows.
4653 Set the grid size (i.e. the number of lines and columns) in the form
4657 Set the outer border margin in pixels.
4660 Set the inner border thickness (i.e. the number of pixels between frames). For
4661 more advanced padding options (such as having different values for the edges),
4662 refer to the pad video filter.
4665 Set the maximum number of frames to render in the given area. It must be less
4666 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
4667 the area will be used.
4671 Alternatively, the options can be specified as a flat string:
4673 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
4675 For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
4678 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
4680 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
4681 duplicating each output frame to accomodate the originally detected frame
4684 Another example to display @code{5} pictures in an area of @code{3x2} frames,
4685 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
4686 mixed flat and named options:
4688 tile=3x2:nb_frames=5:padding=7:margin=2
4693 Perform various types of temporal field interlacing.
4695 Frames are counted starting from 1, so the first input frame is
4698 This filter accepts options in the form of @var{key}=@var{value} pairs
4700 Alternatively, the @var{mode} option can be specified as a value alone,
4701 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
4704 A description of the accepted options follows.
4709 Specify the mode of the interlacing. This option can also be specified
4710 as a value alone. See below for a list of values for this option.
4712 Available values are:
4716 Move odd frames into the upper field, even into the lower field,
4717 generating a double height frame at half framerate.
4720 Only output even frames, odd frames are dropped, generating a frame with
4721 unchanged height at half framerate.
4724 Only output odd frames, even frames are dropped, generating a frame with
4725 unchanged height at half framerate.
4728 Expand each frame to full height, but pad alternate lines with black,
4729 generating a frame with double height at the same input framerate.
4731 @item interleave_top, 4
4732 Interleave the upper field from odd frames with the lower field from
4733 even frames, generating a frame with unchanged height at half framerate.
4735 @item interleave_bottom, 5
4736 Interleave the lower field from odd frames with the upper field from
4737 even frames, generating a frame with unchanged height at half framerate.
4739 @item interlacex2, 6
4740 Double frame rate with unchanged height. Frames are inserted each
4741 containing the second temporal field from the previous input frame and
4742 the first temporal field from the next input frame. This mode relies on
4743 the top_field_first flag. Useful for interlaced video displays with no
4744 field synchronisation.
4747 Numeric values are deprecated but are accepted for backward
4748 compatibility reasons.
4750 Default mode is @code{merge}.
4753 Specify flags influencing the filter process.
4755 Available value for @var{flags} is:
4758 @item low_pass_filter, vlfp
4759 Enable vertical low-pass filtering in the filter.
4760 Vertical low-pass filtering is required when creating an interlaced
4761 destination from a progressive source which contains high-frequency
4762 vertical detail. Filtering will reduce interlace 'twitter' and Moire
4765 Vertical low-pass filtering can only be enabled for @option{mode}
4766 @var{interleave_top} and @var{interleave_bottom}.
4773 Transpose rows with columns in the input video and optionally flip it.
4775 The filter accepts parameters as a list of @var{key}=@var{value}
4776 pairs, separated by ':'. If the key of the first options is omitted,
4777 the arguments are interpreted according to the syntax
4778 @var{dir}:@var{passthrough}.
4782 Specify the transposition direction. Can assume the following values:
4786 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
4794 Rotate by 90 degrees clockwise, that is:
4802 Rotate by 90 degrees counterclockwise, that is:
4810 Rotate by 90 degrees clockwise and vertically flip, that is:
4818 For values between 4-7, the transposition is only done if the input
4819 video geometry is portrait and not landscape. These values are
4820 deprecated, the @code{passthrough} option should be used instead.
4823 Do not apply the transposition if the input geometry matches the one
4824 specified by the specified value. It accepts the following values:
4827 Always apply transposition.
4829 Preserve portrait geometry (when @var{height} >= @var{width}).
4831 Preserve landscape geometry (when @var{width} >= @var{height}).
4834 Default value is @code{none}.
4837 For example to rotate by 90 degrees clockwise and preserve portrait
4840 transpose=dir=1:passthrough=portrait
4843 The command above can also be specified as:
4845 transpose=1:portrait
4850 Sharpen or blur the input video.
4852 It accepts the following parameters:
4853 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
4855 Negative values for the amount will blur the input video, while positive
4856 values will sharpen. All parameters are optional and default to the
4857 equivalent of the string '5:5:1.0:5:5:0.0'.
4862 Set the luma matrix horizontal size. It can be an integer between 3
4863 and 13, default value is 5.
4866 Set the luma matrix vertical size. It can be an integer between 3
4867 and 13, default value is 5.
4870 Set the luma effect strength. It can be a float number between -2.0
4871 and 5.0, default value is 1.0.
4873 @item chroma_msize_x
4874 Set the chroma matrix horizontal size. It can be an integer between 3
4875 and 13, default value is 5.
4877 @item chroma_msize_y
4878 Set the chroma matrix vertical size. It can be an integer between 3
4879 and 13, default value is 5.
4882 Set the chroma effect strength. It can be a float number between -2.0
4883 and 5.0, default value is 0.0.
4888 # Strong luma sharpen effect parameters
4891 # Strong blur of both luma and chroma parameters
4892 unsharp=7:7:-2:7:7:-2
4894 # Use the default values with @command{ffmpeg}
4895 ffmpeg -i in.avi -vf "unsharp" out.mp4
4900 Flip the input video vertically.
4903 ffmpeg -i in.avi -vf "vflip" out.avi
4908 Deinterlace the input video ("yadif" means "yet another deinterlacing
4911 The filter accepts parameters as a list of @var{key}=@var{value}
4912 pairs, separated by ":". If the key of the first options is omitted,
4913 the arguments are interpreted according to syntax
4914 @var{mode}:@var{parity}:@var{deint}.
4916 The description of the accepted parameters follows.
4920 Specify the interlacing mode to adopt. Accept one of the following
4925 output 1 frame for each frame
4927 output 1 frame for each field
4928 @item 2, send_frame_nospatial
4929 like @code{send_frame} but skip spatial interlacing check
4930 @item 3, send_field_nospatial
4931 like @code{send_field} but skip spatial interlacing check
4934 Default value is @code{send_frame}.
4937 Specify the picture field parity assumed for the input interlaced
4938 video. Accept one of the following values:
4942 assume top field first
4944 assume bottom field first
4946 enable automatic detection
4949 Default value is @code{auto}.
4950 If interlacing is unknown or decoder does not export this information,
4951 top field first will be assumed.
4954 Specify which frames to deinterlace. Accept one of the following
4959 deinterlace all frames
4961 only deinterlace frames marked as interlaced
4964 Default value is @code{all}.
4967 @c man end VIDEO FILTERS
4969 @chapter Video Sources
4970 @c man begin VIDEO SOURCES
4972 Below is a description of the currently available video sources.
4976 Buffer video frames, and make them available to the filter chain.
4978 This source is mainly intended for a programmatic use, in particular
4979 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
4981 It accepts a list of options in the form of @var{key}=@var{value} pairs
4982 separated by ":". A description of the accepted options follows.
4987 Specify the size (width and height) of the buffered video frames.
4990 A string representing the pixel format of the buffered video frames.
4991 It may be a number corresponding to a pixel format, or a pixel format
4995 Specify the timebase assumed by the timestamps of the buffered frames.
4998 Specify the frame rate expected for the video stream.
5001 Specify the sample aspect ratio assumed by the video frames.
5004 Specify the optional parameters to be used for the scale filter which
5005 is automatically inserted when an input change is detected in the
5006 input size or format.
5011 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5014 will instruct the source to accept video frames with size 320x240 and
5015 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5016 square pixels (1:1 sample aspect ratio).
5017 Since the pixel format with name "yuv410p" corresponds to the number 6
5018 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5019 this example corresponds to:
5021 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5024 Alternatively, the options can be specified as a flat string, but this
5025 syntax is deprecated:
5027 @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}]
5031 Create a pattern generated by an elementary cellular automaton.
5033 The initial state of the cellular automaton can be defined through the
5034 @option{filename}, and @option{pattern} options. If such options are
5035 not specified an initial state is created randomly.
5037 At each new frame a new row in the video is filled with the result of
5038 the cellular automaton next generation. The behavior when the whole
5039 frame is filled is defined by the @option{scroll} option.
5041 This source accepts a list of options in the form of
5042 @var{key}=@var{value} pairs separated by ":". A description of the
5043 accepted options follows.
5047 Read the initial cellular automaton state, i.e. the starting row, from
5049 In the file, each non-whitespace character is considered an alive
5050 cell, a newline will terminate the row, and further characters in the
5051 file will be ignored.
5054 Read the initial cellular automaton state, i.e. the starting row, from
5055 the specified string.
5057 Each non-whitespace character in the string is considered an alive
5058 cell, a newline will terminate the row, and further characters in the
5059 string will be ignored.
5062 Set the video rate, that is the number of frames generated per second.
5065 @item random_fill_ratio, ratio
5066 Set the random fill ratio for the initial cellular automaton row. It
5067 is a floating point number value ranging from 0 to 1, defaults to
5070 This option is ignored when a file or a pattern is specified.
5072 @item random_seed, seed
5073 Set the seed for filling randomly the initial row, must be an integer
5074 included between 0 and UINT32_MAX. If not specified, or if explicitly
5075 set to -1, the filter will try to use a good random seed on a best
5079 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5080 Default value is 110.
5083 Set the size of the output video.
5085 If @option{filename} or @option{pattern} is specified, the size is set
5086 by default to the width of the specified initial state row, and the
5087 height is set to @var{width} * PHI.
5089 If @option{size} is set, it must contain the width of the specified
5090 pattern string, and the specified pattern will be centered in the
5093 If a filename or a pattern string is not specified, the size value
5094 defaults to "320x518" (used for a randomly generated initial state).
5097 If set to 1, scroll the output upward when all the rows in the output
5098 have been already filled. If set to 0, the new generated row will be
5099 written over the top row just after the bottom row is filled.
5102 @item start_full, full
5103 If set to 1, completely fill the output with generated rows before
5104 outputting the first frame.
5105 This is the default behavior, for disabling set the value to 0.
5108 If set to 1, stitch the left and right row edges together.
5109 This is the default behavior, for disabling set the value to 0.
5112 @subsection Examples
5116 Read the initial state from @file{pattern}, and specify an output of
5119 cellauto=f=pattern:s=200x400
5123 Generate a random initial row with a width of 200 cells, with a fill
5126 cellauto=ratio=2/3:s=200x200
5130 Create a pattern generated by rule 18 starting by a single alive cell
5131 centered on an initial row with width 100:
5133 cellauto=p=@@:s=100x400:full=0:rule=18
5137 Specify a more elaborated initial pattern:
5139 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5146 Generate a Mandelbrot set fractal, and progressively zoom towards the
5147 point specified with @var{start_x} and @var{start_y}.
5149 This source accepts a list of options in the form of
5150 @var{key}=@var{value} pairs separated by ":". A description of the
5151 accepted options follows.
5156 Set the terminal pts value. Default value is 400.
5159 Set the terminal scale value.
5160 Must be a floating point value. Default value is 0.3.
5163 Set the inner coloring mode, that is the algorithm used to draw the
5164 Mandelbrot fractal internal region.
5166 It shall assume one of the following values:
5171 Show time until convergence.
5173 Set color based on point closest to the origin of the iterations.
5178 Default value is @var{mincol}.
5181 Set the bailout value. Default value is 10.0.
5184 Set the maximum of iterations performed by the rendering
5185 algorithm. Default value is 7189.
5188 Set outer coloring mode.
5189 It shall assume one of following values:
5191 @item iteration_count
5192 Set iteration cound mode.
5193 @item normalized_iteration_count
5194 set normalized iteration count mode.
5196 Default value is @var{normalized_iteration_count}.
5199 Set frame rate, expressed as number of frames per second. Default
5203 Set frame size. Default value is "640x480".
5206 Set the initial scale value. Default value is 3.0.
5209 Set the initial x position. Must be a floating point value between
5210 -100 and 100. Default value is -0.743643887037158704752191506114774.
5213 Set the initial y position. Must be a floating point value between
5214 -100 and 100. Default value is -0.131825904205311970493132056385139.
5219 Generate various test patterns, as generated by the MPlayer test filter.
5221 The size of the generated video is fixed, and is 256x256.
5222 This source is useful in particular for testing encoding features.
5224 This source accepts an optional sequence of @var{key}=@var{value} pairs,
5225 separated by ":". The description of the accepted options follows.
5230 Specify the frame rate of the sourced video, as the number of frames
5231 generated per second. It has to be a string in the format
5232 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5233 number or a valid video frame rate abbreviation. The default value is
5237 Set the video duration of the sourced video. The accepted syntax is:
5242 See also the function @code{av_parse_time()}.
5244 If not specified, or the expressed duration is negative, the video is
5245 supposed to be generated forever.
5249 Set the number or the name of the test to perform. Supported tests are:
5264 Default value is "all", which will cycle through the list of all tests.
5267 For example the following:
5272 will generate a "dc_luma" test pattern.
5276 Provide a frei0r source.
5278 To enable compilation of this filter you need to install the frei0r
5279 header and configure FFmpeg with @code{--enable-frei0r}.
5281 The source supports the syntax:
5283 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
5286 @var{size} is the size of the video to generate, may be a string of the
5287 form @var{width}x@var{height} or a frame size abbreviation.
5288 @var{rate} is the rate of the video to generate, may be a string of
5289 the form @var{num}/@var{den} or a frame rate abbreviation.
5290 @var{src_name} is the name to the frei0r source to load. For more
5291 information regarding frei0r and how to set the parameters read the
5292 section @ref{frei0r} in the description of the video filters.
5294 For example, to generate a frei0r partik0l source with size 200x200
5295 and frame rate 10 which is overlayed on the overlay filter main input:
5297 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
5302 Generate a life pattern.
5304 This source is based on a generalization of John Conway's life game.
5306 The sourced input represents a life grid, each pixel represents a cell
5307 which can be in one of two possible states, alive or dead. Every cell
5308 interacts with its eight neighbours, which are the cells that are
5309 horizontally, vertically, or diagonally adjacent.
5311 At each interaction the grid evolves according to the adopted rule,
5312 which specifies the number of neighbor alive cells which will make a
5313 cell stay alive or born. The @option{rule} option allows to specify
5316 This source accepts a list of options in the form of
5317 @var{key}=@var{value} pairs separated by ":". A description of the
5318 accepted options follows.
5322 Set the file from which to read the initial grid state. In the file,
5323 each non-whitespace character is considered an alive cell, and newline
5324 is used to delimit the end of each row.
5326 If this option is not specified, the initial grid is generated
5330 Set the video rate, that is the number of frames generated per second.
5333 @item random_fill_ratio, ratio
5334 Set the random fill ratio for the initial random grid. It is a
5335 floating point number value ranging from 0 to 1, defaults to 1/PHI.
5336 It is ignored when a file is specified.
5338 @item random_seed, seed
5339 Set the seed for filling the initial random grid, must be an integer
5340 included between 0 and UINT32_MAX. If not specified, or if explicitly
5341 set to -1, the filter will try to use a good random seed on a best
5347 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
5348 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
5349 @var{NS} specifies the number of alive neighbor cells which make a
5350 live cell stay alive, and @var{NB} the number of alive neighbor cells
5351 which make a dead cell to become alive (i.e. to "born").
5352 "s" and "b" can be used in place of "S" and "B", respectively.
5354 Alternatively a rule can be specified by an 18-bits integer. The 9
5355 high order bits are used to encode the next cell state if it is alive
5356 for each number of neighbor alive cells, the low order bits specify
5357 the rule for "borning" new cells. Higher order bits encode for an
5358 higher number of neighbor cells.
5359 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
5360 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
5362 Default value is "S23/B3", which is the original Conway's game of life
5363 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
5364 cells, and will born a new cell if there are three alive cells around
5368 Set the size of the output video.
5370 If @option{filename} is specified, the size is set by default to the
5371 same size of the input file. If @option{size} is set, it must contain
5372 the size specified in the input file, and the initial grid defined in
5373 that file is centered in the larger resulting area.
5375 If a filename is not specified, the size value defaults to "320x240"
5376 (used for a randomly generated initial grid).
5379 If set to 1, stitch the left and right grid edges together, and the
5380 top and bottom edges also. Defaults to 1.
5383 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
5384 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
5385 value from 0 to 255.
5388 Set the color of living (or new born) cells.
5391 Set the color of dead cells. If @option{mold} is set, this is the first color
5392 used to represent a dead cell.
5395 Set mold color, for definitely dead and moldy cells.
5398 @subsection Examples
5402 Read a grid from @file{pattern}, and center it on a grid of size
5405 life=f=pattern:s=300x300
5409 Generate a random grid of size 200x200, with a fill ratio of 2/3:
5411 life=ratio=2/3:s=200x200
5415 Specify a custom rule for evolving a randomly generated grid:
5421 Full example with slow death effect (mold) using @command{ffplay}:
5423 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
5427 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
5429 The @code{color} source provides an uniformly colored input.
5431 The @code{nullsrc} source returns unprocessed video frames. It is
5432 mainly useful to be employed in analysis / debugging tools, or as the
5433 source for filters which ignore the input data.
5435 The @code{rgbtestsrc} source generates an RGB test pattern useful for
5436 detecting RGB vs BGR issues. You should see a red, green and blue
5437 stripe from top to bottom.
5439 The @code{smptebars} source generates a color bars pattern, based on
5440 the SMPTE Engineering Guideline EG 1-1990.
5442 The @code{testsrc} source generates a test video pattern, showing a
5443 color pattern, a scrolling gradient and a timestamp. This is mainly
5444 intended for testing purposes.
5446 These sources accept an optional sequence of @var{key}=@var{value} pairs,
5447 separated by ":". The description of the accepted options follows.
5452 Specify the color of the source, only used in the @code{color}
5453 source. It can be the name of a color (case insensitive match) or a
5454 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
5455 default value is "black".
5458 Specify the size of the sourced video, it may be a string of the form
5459 @var{width}x@var{height}, or the name of a size abbreviation. The
5460 default value is "320x240".
5463 Specify the frame rate of the sourced video, as the number of frames
5464 generated per second. It has to be a string in the format
5465 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5466 number or a valid video frame rate abbreviation. The default value is
5470 Set the sample aspect ratio of the sourced video.
5473 Set the video duration of the sourced video. The accepted syntax is:
5475 [-]HH[:MM[:SS[.m...]]]
5478 See also the function @code{av_parse_time()}.
5480 If not specified, or the expressed duration is negative, the video is
5481 supposed to be generated forever.
5484 Set the number of decimals to show in the timestamp, only used in the
5485 @code{testsrc} source.
5487 The displayed timestamp value will correspond to the original
5488 timestamp value multiplied by the power of 10 of the specified
5489 value. Default value is 0.
5492 For example the following:
5494 testsrc=duration=5.3:size=qcif:rate=10
5497 will generate a video with a duration of 5.3 seconds, with size
5498 176x144 and a frame rate of 10 frames per second.
5500 The following graph description will generate a red source
5501 with an opacity of 0.2, with size "qcif" and a frame rate of 10
5504 color=c=red@@0.2:s=qcif:r=10
5507 If the input content is to be ignored, @code{nullsrc} can be used. The
5508 following command generates noise in the luminance plane by employing
5509 the @code{geq} filter:
5511 nullsrc=s=256x256, geq=random(1)*255:128:128
5514 @c man end VIDEO SOURCES
5516 @chapter Video Sinks
5517 @c man begin VIDEO SINKS
5519 Below is a description of the currently available video sinks.
5523 Buffer video frames, and make them available to the end of the filter
5526 This sink is mainly intended for a programmatic use, in particular
5527 through the interface defined in @file{libavfilter/buffersink.h}.
5529 It does not require a string parameter in input, but you need to
5530 specify a pointer to a list of supported pixel formats terminated by
5531 -1 in the opaque parameter provided to @code{avfilter_init_filter}
5532 when initializing this sink.
5536 Null video sink, do absolutely nothing with the input video. It is
5537 mainly useful as a template and to be employed in analysis / debugging
5540 @c man end VIDEO SINKS
5542 @chapter Multimedia Filters
5543 @c man begin MULTIMEDIA FILTERS
5545 Below is a description of the currently available multimedia filters.
5547 @section aselect, select
5548 Select frames to pass in output.
5550 These filters accept a single option @option{expr} or @option{e}
5551 specifying the select expression, which can be specified either by
5552 specyfing @code{expr=VALUE} or specifying the expression
5555 The select expression is evaluated for each input frame. If the
5556 evaluation result is a non-zero value, the frame is selected and
5557 passed to the output, otherwise it is discarded.
5559 The expression can contain the following constants:
5563 the sequential number of the filtered frame, starting from 0
5566 the sequential number of the selected frame, starting from 0
5568 @item prev_selected_n
5569 the sequential number of the last selected frame, NAN if undefined
5572 timebase of the input timestamps
5575 the PTS (Presentation TimeStamp) of the filtered video frame,
5576 expressed in @var{TB} units, NAN if undefined
5579 the PTS (Presentation TimeStamp) of the filtered video frame,
5580 expressed in seconds, NAN if undefined
5583 the PTS of the previously filtered video frame, NAN if undefined
5585 @item prev_selected_pts
5586 the PTS of the last previously filtered video frame, NAN if undefined
5588 @item prev_selected_t
5589 the PTS of the last previously selected video frame, NAN if undefined
5592 the PTS of the first video frame in the video, NAN if undefined
5595 the time of the first video frame in the video, NAN if undefined
5597 @item pict_type @emph{(video only)}
5598 the type of the filtered frame, can assume one of the following
5610 @item interlace_type @emph{(video only)}
5611 the frame interlace type, can assume one of the following values:
5614 the frame is progressive (not interlaced)
5616 the frame is top-field-first
5618 the frame is bottom-field-first
5621 @item consumed_sample_n @emph{(audio only)}
5622 the number of selected samples before the current frame
5624 @item samples_n @emph{(audio only)}
5625 the number of samples in the current frame
5627 @item sample_rate @emph{(audio only)}
5628 the input sample rate
5631 1 if the filtered frame is a key-frame, 0 otherwise
5634 the position in the file of the filtered frame, -1 if the information
5635 is not available (e.g. for synthetic video)
5637 @item scene @emph{(video only)}
5638 value between 0 and 1 to indicate a new scene; a low value reflects a low
5639 probability for the current frame to introduce a new scene, while a higher
5640 value means the current frame is more likely to be one (see the example below)
5644 The default value of the select expression is "1".
5646 @subsection Examples
5650 Select all frames in input:
5655 The example above is the same as:
5667 Select only I-frames:
5669 select='eq(pict_type\,I)'
5673 Select one frame every 100:
5675 select='not(mod(n\,100))'
5679 Select only frames contained in the 10-20 time interval:
5681 select='gte(t\,10)*lte(t\,20)'
5685 Select only I frames contained in the 10-20 time interval:
5687 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
5691 Select frames with a minimum distance of 10 seconds:
5693 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
5697 Use aselect to select only audio frames with samples number > 100:
5699 aselect='gt(samples_n\,100)'
5703 Create a mosaic of the first scenes:
5705 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
5708 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
5712 @section asendcmd, sendcmd
5714 Send commands to filters in the filtergraph.
5716 These filters read commands to be sent to other filters in the
5719 @code{asendcmd} must be inserted between two audio filters,
5720 @code{sendcmd} must be inserted between two video filters, but apart
5721 from that they act the same way.
5723 The specification of commands can be provided in the filter arguments
5724 with the @var{commands} option, or in a file specified by the
5725 @var{filename} option.
5727 These filters accept the following options:
5730 Set the commands to be read and sent to the other filters.
5732 Set the filename of the commands to be read and sent to the other
5736 @subsection Commands syntax
5738 A commands description consists of a sequence of interval
5739 specifications, comprising a list of commands to be executed when a
5740 particular event related to that interval occurs. The occurring event
5741 is typically the current frame time entering or leaving a given time
5744 An interval is specified by the following syntax:
5746 @var{START}[-@var{END}] @var{COMMANDS};
5749 The time interval is specified by the @var{START} and @var{END} times.
5750 @var{END} is optional and defaults to the maximum time.
5752 The current frame time is considered within the specified interval if
5753 it is included in the interval [@var{START}, @var{END}), that is when
5754 the time is greater or equal to @var{START} and is lesser than
5757 @var{COMMANDS} consists of a sequence of one or more command
5758 specifications, separated by ",", relating to that interval. The
5759 syntax of a command specification is given by:
5761 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
5764 @var{FLAGS} is optional and specifies the type of events relating to
5765 the time interval which enable sending the specified command, and must
5766 be a non-null sequence of identifier flags separated by "+" or "|" and
5767 enclosed between "[" and "]".
5769 The following flags are recognized:
5772 The command is sent when the current frame timestamp enters the
5773 specified interval. In other words, the command is sent when the
5774 previous frame timestamp was not in the given interval, and the
5778 The command is sent when the current frame timestamp leaves the
5779 specified interval. In other words, the command is sent when the
5780 previous frame timestamp was in the given interval, and the
5784 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
5787 @var{TARGET} specifies the target of the command, usually the name of
5788 the filter class or a specific filter instance name.
5790 @var{COMMAND} specifies the name of the command for the target filter.
5792 @var{ARG} is optional and specifies the optional list of argument for
5793 the given @var{COMMAND}.
5795 Between one interval specification and another, whitespaces, or
5796 sequences of characters starting with @code{#} until the end of line,
5797 are ignored and can be used to annotate comments.
5799 A simplified BNF description of the commands specification syntax
5802 @var{COMMAND_FLAG} ::= "enter" | "leave"
5803 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
5804 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
5805 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
5806 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
5807 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
5810 @subsection Examples
5814 Specify audio tempo change at second 4:
5816 asendcmd=c='4.0 atempo tempo 1.5',atempo
5820 Specify a list of drawtext and hue commands in a file.
5822 # show text in the interval 5-10
5823 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
5824 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
5826 # desaturate the image in the interval 15-20
5827 15.0-20.0 [enter] hue reinit s=0,
5828 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
5829 [leave] hue reinit s=1,
5830 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
5832 # apply an exponential saturation fade-out effect, starting from time 25
5833 25 [enter] hue s=exp(t-25)
5836 A filtergraph allowing to read and process the above command list
5837 stored in a file @file{test.cmd}, can be specified with:
5839 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
5844 @section asetpts, setpts
5846 Change the PTS (presentation timestamp) of the input frames.
5848 @code{asetpts} works on audio frames, @code{setpts} on video frames.
5850 Accept in input an expression evaluated through the eval API, which
5851 can contain the following constants:
5855 frame rate, only defined for constant frame-rate video
5858 the presentation timestamp in input
5861 the count of the input frame, starting from 0.
5863 @item NB_CONSUMED_SAMPLES
5864 the number of consumed samples, not including the current frame (only
5868 the number of samples in the current frame (only audio)
5874 the PTS of the first frame
5877 the time in seconds of the first frame
5880 tell if the current frame is interlaced
5883 the time in seconds of the current frame
5889 original position in the file of the frame, or undefined if undefined
5890 for the current frame
5896 previous input time in seconds
5902 previous output time in seconds
5905 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
5909 wallclock (RTC) time at the start of the movie in microseconds
5912 @subsection Examples
5916 Start counting PTS from zero
5922 Apply fast motion effect:
5928 Apply slow motion effect:
5934 Set fixed rate of 25 frames per second:
5940 Set fixed rate 25 fps with some jitter:
5942 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
5946 Apply an offset of 10 seconds to the input PTS:
5952 Generate timestamps from a "live source" and rebase onto the current timebase:
5954 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
5960 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
5961 it unchanged. By default, it logs a message at a frequency of 10Hz with the
5962 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
5963 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
5965 The filter also has a video output (see the @var{video} option) with a real
5966 time graph to observe the loudness evolution. The graphic contains the logged
5967 message mentioned above, so it is not printed anymore when this option is set,
5968 unless the verbose logging is set. The main graphing area contains the
5969 short-term loudness (3 seconds of analysis), and the gauge on the right is for
5970 the momentary loudness (400 milliseconds).
5972 More information about the Loudness Recommendation EBU R128 on
5973 @url{http://tech.ebu.ch/loudness}.
5975 The filter accepts the following named parameters:
5980 Activate the video output. The audio stream is passed unchanged whether this
5981 option is set or no. The video stream will be the first output stream if
5982 activated. Default is @code{0}.
5985 Set the video size. This option is for video only. Default and minimum
5986 resolution is @code{640x480}.
5989 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
5990 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
5991 other integer value between this range is allowed.
5995 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
5997 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6000 Run an analysis with @command{ffmpeg}:
6002 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6005 @section settb, asettb
6007 Set the timebase to use for the output frames timestamps.
6008 It is mainly useful for testing timebase configuration.
6010 It accepts in input an arithmetic expression representing a rational.
6011 The expression can contain the constants "AVTB" (the
6012 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
6015 The default value for the input is "intb".
6017 @subsection Examples
6021 Set the timebase to 1/25:
6027 Set the timebase to 1/10:
6033 Set the timebase to 1001/1000:
6039 Set the timebase to 2*intb:
6045 Set the default timebase value:
6053 Concatenate audio and video streams, joining them together one after the
6056 The filter works on segments of synchronized video and audio streams. All
6057 segments must have the same number of streams of each type, and that will
6058 also be the number of streams at output.
6060 The filter accepts the following named parameters:
6064 Set the number of segments. Default is 2.
6067 Set the number of output video streams, that is also the number of video
6068 streams in each segment. Default is 1.
6071 Set the number of output audio streams, that is also the number of video
6072 streams in each segment. Default is 0.
6075 Activate unsafe mode: do not fail if segments have a different format.
6079 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6080 @var{a} audio outputs.
6082 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6083 segment, in the same order as the outputs, then the inputs for the second
6086 Related streams do not always have exactly the same duration, for various
6087 reasons including codec frame size or sloppy authoring. For that reason,
6088 related synchronized streams (e.g. a video and its audio track) should be
6089 concatenated at once. The concat filter will use the duration of the longest
6090 stream in each segment (except the last one), and if necessary pad shorter
6091 audio streams with silence.
6093 For this filter to work correctly, all segments must start at timestamp 0.
6095 All corresponding streams must have the same parameters in all segments; the
6096 filtering system will automatically select a common pixel format for video
6097 streams, and a common sample format, sample rate and channel layout for
6098 audio streams, but other settings, such as resolution, must be converted
6099 explicitly by the user.
6101 Different frame rates are acceptable but will result in variable frame rate
6102 at output; be sure to configure the output file to handle it.
6107 Concatenate an opening, an episode and an ending, all in bilingual version
6108 (video in stream 0, audio in streams 1 and 2):
6110 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6111 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6112 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6113 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6117 Concatenate two parts, handling audio and video separately, using the
6118 (a)movie sources, and adjusting the resolution:
6120 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6121 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6122 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
6124 Note that a desync will happen at the stitch if the audio and video streams
6125 do not have exactly the same duration in the first file.
6129 @section showspectrum
6131 Convert input audio to a video output, representing the audio frequency
6134 The filter accepts the following named parameters:
6137 Specify the video size for the output. Default value is @code{640x512}.
6140 Specify if the spectrum should slide along the window. Default value is
6144 Specify display mode.
6146 It accepts the following values:
6149 all channels are displayed in the same row
6151 all channels are displayed in separate rows
6154 Default value is @samp{combined}.
6157 Specify display color mode.
6159 It accepts the following values:
6162 each channel is displayed in a separate color
6164 each channel is is displayed using the same color scheme
6167 Default value is @samp{channel}.
6170 Specify scale used for calculating intensity color values.
6172 It accepts the following values:
6177 square root, default
6184 Default value is @samp{sqrt}.
6187 Set saturation modifier for displayed colors. Negative values provide
6188 alternative color scheme. @code{0} is no saturation at all.
6189 Saturation must be in [-10.0, 10.0] range.
6190 Default value is @code{1}.
6193 The usage is very similar to the showwaves filter; see the examples in that
6198 Convert input audio to a video output, representing the samples waves.
6200 The filter accepts the following named parameters:
6205 Available values are:
6208 Draw a point for each sample.
6211 Draw a vertical line for each sample.
6214 Default value is @code{point}.
6217 Set the number of samples which are printed on the same column. A
6218 larger value will decrease the frame rate. Must be a positive
6219 integer. This option can be set only if the value for @var{rate}
6220 is not explicitly specified.
6223 Set the (approximate) output frame rate. This is done by setting the
6224 option @var{n}. Default value is "25".
6227 Specify the video size for the output. Default value is "600x240".
6230 Some examples follow.
6233 Output the input file audio and the corresponding video representation
6236 amovie=a.mp3,asplit[out0],showwaves[out1]
6240 Create a synthetic signal and show it with showwaves, forcing a
6241 framerate of 30 frames per second:
6243 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
6247 @c man end MULTIMEDIA FILTERS
6249 @chapter Multimedia Sources
6250 @c man begin MULTIMEDIA SOURCES
6252 Below is a description of the currently available multimedia sources.
6256 This is the same as @ref{movie} source, except it selects an audio
6262 Read audio and/or video stream(s) from a movie container.
6264 It accepts the syntax: @var{movie_name}[:@var{options}] where
6265 @var{movie_name} is the name of the resource to read (not necessarily
6266 a file but also a device or a stream accessed through some protocol),
6267 and @var{options} is an optional sequence of @var{key}=@var{value}
6268 pairs, separated by ":".
6270 The description of the accepted options follows.
6274 @item format_name, f
6275 Specifies the format assumed for the movie to read, and can be either
6276 the name of a container or an input device. If not specified the
6277 format is guessed from @var{movie_name} or by probing.
6279 @item seek_point, sp
6280 Specifies the seek point in seconds, the frames will be output
6281 starting from this seek point, the parameter is evaluated with
6282 @code{av_strtod} so the numerical value may be suffixed by an IS
6283 postfix. Default value is "0".
6286 Specifies the streams to read. Several streams can be specified,
6287 separated by "+". The source will then have as many outputs, in the
6288 same order. The syntax is explained in the ``Stream specifiers''
6289 section in the ffmpeg manual. Two special names, "dv" and "da" specify
6290 respectively the default (best suited) video and audio stream. Default
6291 is "dv", or "da" if the filter is called as "amovie".
6293 @item stream_index, si
6294 Specifies the index of the video stream to read. If the value is -1,
6295 the best suited video stream will be automatically selected. Default
6296 value is "-1". Deprecated. If the filter is called "amovie", it will select
6297 audio instead of video.
6300 Specifies how many times to read the stream in sequence.
6301 If the value is less than 1, the stream will be read again and again.
6302 Default value is "1".
6304 Note that when the movie is looped the source timestamps are not
6305 changed, so it will generate non monotonically increasing timestamps.
6308 This filter allows to overlay a second video on top of main input of
6309 a filtergraph as shown in this graph:
6311 input -----------> deltapts0 --> overlay --> output
6314 movie --> scale--> deltapts1 -------+
6317 Some examples follow.
6321 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
6322 on top of the input labelled as "in":
6324 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6325 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6329 Read from a video4linux2 device, and overlay it on top of the input
6332 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6333 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6337 Read the first video stream and the audio stream with id 0x81 from
6338 dvd.vob; the video is connected to the pad named "video" and the audio is
6339 connected to the pad named "audio":
6341 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
6345 @c man end MULTIMEDIA SOURCES