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 color component graph. In row mode graph in the left side represents
3150 color component value 0 and right side represents value = 255. In column mode top
3151 side represents color component value = 0 and bottom side represents value = 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}.
3173 Set display mode for @code{waveform}.
3174 It accepts the following values:
3177 Display separate waveforms for the color components side by side in
3178 @code{row} mode or one below other in @code{column} mode.
3180 In this display mode it is easy to spot color casts in the highlights and
3181 shadows of an image, by comparing the contours of the top and the bottom
3182 of each waveform. Since whites, grays, and blacks are characterized by
3183 exactly equal amounts of red, green, and blue, neutral areas of the
3184 picture should display three waveforms of roughly equal height.
3185 If not, the correction is easy to make by making adjustments to level the
3189 Presents information that's identical to that in the @code{parade}, except
3190 that the waveforms representing color components are superimposed directly
3193 This display mode can make it easier to spot the relative differences or
3194 similarities in overlapping areas of the color components that are supposed
3195 to be identical, such as neutral whites, grays, or blacks.
3197 Default is @code{parade}.
3200 @subsection Examples
3205 Calculate and draw histogram:
3207 ffplay -i input -vf histogram
3214 High precision/quality 3d denoise filter. This filter aims to reduce
3215 image noise producing smooth images and making still images really
3216 still. It should enhance compressibility.
3218 It accepts the following optional parameters:
3219 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3223 a non-negative float number which specifies spatial luma strength,
3226 @item chroma_spatial
3227 a non-negative float number which specifies spatial chroma strength,
3228 defaults to 3.0*@var{luma_spatial}/4.0
3231 a float number which specifies luma temporal strength, defaults to
3232 6.0*@var{luma_spatial}/4.0
3235 a float number which specifies chroma temporal strength, defaults to
3236 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3241 Modify the hue and/or the saturation of the input.
3243 This filter accepts the following optional named options:
3247 Specify the hue angle as a number of degrees. It accepts a float
3248 number or an expression, and defaults to 0.0.
3251 Specify the hue angle as a number of degrees. It accepts a float
3252 number or an expression, and defaults to 0.0.
3255 Specify the saturation in the [-10,10] range. It accepts a float number and
3259 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3260 following constants:
3264 frame count of the input frame starting from 0
3267 presentation timestamp of the input frame expressed in time base units
3270 frame rate of the input video, NAN if the input frame rate is unknown
3273 timestamp expressed in seconds, NAN if the input timestamp is unknown
3276 time base of the input video
3279 The options can also be set using the syntax: @var{hue}:@var{saturation}
3281 In this case @var{hue} is expressed in degrees.
3283 Some examples follow:
3286 Set the hue to 90 degrees and the saturation to 1.0:
3292 Same command but expressing the hue in radians:
3298 Same command without named options, hue must be expressed in degrees:
3304 Note that "h:s" syntax does not support expressions for the values of
3305 h and s, so the following example will issue an error:
3311 Rotate hue and make the saturation swing between 0
3312 and 2 over a period of 1 second:
3314 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3318 Apply a 3 seconds saturation fade-in effect starting at 0:
3323 The general fade-in expression can be written as:
3325 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3329 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3331 hue="s=max(0\, min(1\, (8-t)/3))"
3334 The general fade-out expression can be written as:
3336 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3341 @subsection Commands
3343 This filter supports the following command:
3346 Modify the hue and/or the saturation of the input video.
3347 The command accepts the same named options and syntax than when calling the
3348 filter from the command-line.
3350 If a parameter is omitted, it is kept at its current value.
3355 Detect video interlacing type.
3357 This filter tries to detect if the input is interlaced or progressive,
3358 top or bottom field first.
3362 Deinterleave or interleave fields.
3364 This filter allows to process interlaced images fields without
3365 deinterlacing them. Deinterleaving splits the input frame into 2
3366 fields (so called half pictures). Odd lines are moved to the top
3367 half of the output image, even lines to the bottom half.
3368 You can process (filter) them independently and then re-interleave them.
3370 It accepts a list of options in the form of @var{key}=@var{value} pairs
3371 separated by ":". A description of the accepted options follows.
3375 @item chroma_mode, s
3377 Available values for @var{luma_mode}, @var{chroma_mode} and
3378 @var{alpha_mode} are:
3384 @item deinterleave, d
3385 Deinterleave fields, placing one above the other.
3388 Interleave fields. Reverse the effect of deinterleaving.
3390 Default value is @code{none}.
3393 @item chroma_swap, cs
3394 @item alpha_swap, as
3395 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3400 Deinterlace input video by applying Donald Graft's adaptive kernel
3401 deinterling. Work on interlaced parts of a video to produce
3404 This filter accepts parameters as a list of @var{key}=@var{value}
3405 pairs, separated by ":". If the key of the first options is omitted,
3406 the arguments are interpreted according to the following syntax:
3407 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3409 The description of the accepted parameters follows.
3413 Set the threshold which affects the filter's tolerance when
3414 determining if a pixel line must be processed. It must be an integer
3415 in the range [0,255] and defaults to 10. A value of 0 will result in
3416 applying the process on every pixels.
3419 Paint pixels exceeding the threshold value to white if set to 1.
3423 Set the fields order. Swap fields if set to 1, leave fields alone if
3427 Enable additional sharpening if set to 1. Default is 0.
3430 Enable twoway sharpening if set to 1. Default is 0.
3433 @subsection Examples
3437 Apply default values:
3439 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3443 Enable additional sharpening:
3449 Paint processed pixels in white:
3455 @section lut, lutrgb, lutyuv
3457 Compute a look-up table for binding each pixel component input value
3458 to an output value, and apply it to input video.
3460 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3461 to an RGB input video.
3463 These filters accept in input a ":"-separated list of options, which
3464 specify the expressions used for computing the lookup table for the
3465 corresponding pixel component values.
3467 The @var{lut} filter requires either YUV or RGB pixel formats in
3468 input, and accepts the options:
3471 set first pixel component expression
3473 set second pixel component expression
3475 set third pixel component expression
3477 set fourth pixel component expression, corresponds to the alpha component
3480 The exact component associated to each option depends on the format in
3483 The @var{lutrgb} filter requires RGB pixel formats in input, and
3484 accepts the options:
3487 set red component expression
3489 set green component expression
3491 set blue component expression
3493 alpha component expression
3496 The @var{lutyuv} filter requires YUV pixel formats in input, and
3497 accepts the options:
3500 set Y/luminance component expression
3502 set U/Cb component expression
3504 set V/Cr component expression
3506 set alpha component expression
3509 The expressions can contain the following constants and functions:
3513 the input width and height
3516 input value for the pixel component
3519 the input value clipped in the @var{minval}-@var{maxval} range
3522 maximum value for the pixel component
3525 minimum value for the pixel component
3528 the negated value for the pixel component value clipped in the
3529 @var{minval}-@var{maxval} range , it corresponds to the expression
3530 "maxval-clipval+minval"
3533 the computed value in @var{val} clipped in the
3534 @var{minval}-@var{maxval} range
3536 @item gammaval(gamma)
3537 the computed gamma correction value of the pixel component value
3538 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3540 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3544 All expressions default to "val".
3546 @subsection Examples
3552 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3553 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3556 The above is the same as:
3558 lutrgb="r=negval:g=negval:b=negval"
3559 lutyuv="y=negval:u=negval:v=negval"
3569 Remove chroma components, turns the video into a graytone image:
3571 lutyuv="u=128:v=128"
3575 Apply a luma burning effect:
3581 Remove green and blue components:
3587 Set a constant alpha channel value on input:
3589 format=rgba,lutrgb=a="maxval-minval/2"
3593 Correct luminance gamma by a 0.5 factor:
3595 lutyuv=y=gammaval(0.5)
3601 Apply an MPlayer filter to the input video.
3603 This filter provides a wrapper around most of the filters of
3606 This wrapper is considered experimental. Some of the wrapped filters
3607 may not work properly and we may drop support for them, as they will
3608 be implemented natively into FFmpeg. Thus you should avoid
3609 depending on them when writing portable scripts.
3611 The filters accepts the parameters:
3612 @var{filter_name}[:=]@var{filter_params}
3614 @var{filter_name} is the name of a supported MPlayer filter,
3615 @var{filter_params} is a string containing the parameters accepted by
3618 The list of the currently supported filters follows:
3651 The parameter syntax and behavior for the listed filters are the same
3652 of the corresponding MPlayer filters. For detailed instructions check
3653 the "VIDEO FILTERS" section in the MPlayer manual.
3655 Some examples follow:
3658 Adjust gamma, brightness, contrast:
3664 Add temporal noise to input video:
3670 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3676 This filter accepts an integer in input, if non-zero it negates the
3677 alpha component (if available). The default value in input is 0.
3681 Force libavfilter not to use any of the specified pixel formats for the
3682 input to the next filter.
3684 The filter accepts a list of pixel format names, separated by ":",
3685 for example "yuv420p:monow:rgb24".
3687 Some examples follow:
3689 # force libavfilter to use a format different from "yuv420p" for the
3690 # input to the vflip filter
3691 noformat=yuv420p,vflip
3693 # convert the input video to any of the formats not contained in the list
3694 noformat=yuv420p:yuv444p:yuv410p
3699 Pass the video source unchanged to the output.
3703 Apply video transform using libopencv.
3705 To enable this filter install libopencv library and headers and
3706 configure FFmpeg with @code{--enable-libopencv}.
3708 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3710 @var{filter_name} is the name of the libopencv filter to apply.
3712 @var{filter_params} specifies the parameters to pass to the libopencv
3713 filter. If not specified the default values are assumed.
3715 Refer to the official libopencv documentation for more precise
3717 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3719 Follows the list of supported libopencv filters.
3724 Dilate an image by using a specific structuring element.
3725 This filter corresponds to the libopencv function @code{cvDilate}.
3727 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3729 @var{struct_el} represents a structuring element, and has the syntax:
3730 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3732 @var{cols} and @var{rows} represent the number of columns and rows of
3733 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3734 point, and @var{shape} the shape for the structuring element, and
3735 can be one of the values "rect", "cross", "ellipse", "custom".
3737 If the value for @var{shape} is "custom", it must be followed by a
3738 string of the form "=@var{filename}". The file with name
3739 @var{filename} is assumed to represent a binary image, with each
3740 printable character corresponding to a bright pixel. When a custom
3741 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3742 or columns and rows of the read file are assumed instead.
3744 The default value for @var{struct_el} is "3x3+0x0/rect".
3746 @var{nb_iterations} specifies the number of times the transform is
3747 applied to the image, and defaults to 1.
3749 Follow some example:
3751 # use the default values
3754 # dilate using a structuring element with a 5x5 cross, iterate two times
3755 ocv=dilate=5x5+2x2/cross:2
3757 # read the shape from the file diamond.shape, iterate two times
3758 # the file diamond.shape may contain a pattern of characters like this:
3764 # the specified cols and rows are ignored (but not the anchor point coordinates)
3765 ocv=0x0+2x2/custom=diamond.shape:2
3770 Erode an image by using a specific structuring element.
3771 This filter corresponds to the libopencv function @code{cvErode}.
3773 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3774 with the same syntax and semantics as the @ref{dilate} filter.
3778 Smooth the input video.
3780 The filter takes the following parameters:
3781 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3783 @var{type} is the type of smooth filter to apply, and can be one of
3784 the following values: "blur", "blur_no_scale", "median", "gaussian",
3785 "bilateral". The default value is "gaussian".
3787 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3788 parameters whose meanings depend on smooth type. @var{param1} and
3789 @var{param2} accept integer positive values or 0, @var{param3} and
3790 @var{param4} accept float values.
3792 The default value for @var{param1} is 3, the default value for the
3793 other parameters is 0.
3795 These parameters correspond to the parameters assigned to the
3796 libopencv function @code{cvSmooth}.
3801 Overlay one video on top of another.
3803 It takes two inputs and one output, the first input is the "main"
3804 video on which the second input is overlayed.
3806 This filter accepts a list of @var{key}=@var{value} pairs as argument,
3807 separated by ":". If the key of the first options is omitted, the
3808 arguments are interpreted according to the syntax @var{x}:@var{y}.
3810 A description of the accepted options follows.
3814 Set the expression for the x and y coordinates of the overlayed video
3815 on the main video. Default value is 0.
3817 The @var{x} and @var{y} expressions can contain the following
3820 @item main_w, main_h
3821 main input width and height
3824 same as @var{main_w} and @var{main_h}
3826 @item overlay_w, overlay_h
3827 overlay input width and height
3830 same as @var{overlay_w} and @var{overlay_h}
3834 If set to 1, force the filter to accept inputs in the RGB
3835 color space. Default value is 0.
3838 Be aware that frames are taken from each input video in timestamp
3839 order, hence, if their initial timestamps differ, it is a a good idea
3840 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
3841 have them begin in the same zero timestamp, as it does the example for
3842 the @var{movie} filter.
3844 You can chain together more overlays but you should test the
3845 efficiency of such approach.
3847 @subsection Examples
3851 Draw the overlay at 10 pixels from the bottom right corner of the main
3854 overlay=main_w-overlay_w-10:main_h-overlay_h-10
3857 Using named options the example above becomes:
3859 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
3863 Insert a transparent PNG logo in the bottom left corner of the input,
3864 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
3866 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
3870 Insert 2 different transparent PNG logos (second logo on bottom
3871 right corner) using the @command{ffmpeg} tool:
3873 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
3877 Add a transparent color layer on top of the main video, WxH specifies
3878 the size of the main input to the overlay filter:
3880 color=red@@.3:WxH [over]; [in][over] overlay [out]
3884 Play an original video and a filtered version (here with the deshake
3885 filter) side by side using the @command{ffplay} tool:
3887 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3890 The above command is the same as:
3892 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3896 Chain several overlays in cascade:
3898 nullsrc=s=200x200 [bg];
3899 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
3900 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
3901 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
3902 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
3903 [in3] null, [mid2] overlay=100:100 [out0]
3910 Add paddings to the input image, and place the original input at the
3911 given coordinates @var{x}, @var{y}.
3913 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
3916 If the key of the first options is omitted, the arguments are
3917 interpreted according to the syntax
3918 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3920 A description of the accepted options follows.
3925 Specify an expression for the size of the output image with the
3926 paddings added. If the value for @var{width} or @var{height} is 0, the
3927 corresponding input size is used for the output.
3929 The @var{width} expression can reference the value set by the
3930 @var{height} expression, and vice versa.
3932 The default value of @var{width} and @var{height} is 0.
3936 Specify an expression for the offsets where to place the input image
3937 in the padded area with respect to the top/left border of the output
3940 The @var{x} expression can reference the value set by the @var{y}
3941 expression, and vice versa.
3943 The default value of @var{x} and @var{y} is 0.
3946 Specify the color of the padded area, it can be the name of a color
3947 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3949 The default value of @var{color} is "black".
3952 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
3953 options are expressions containing the following constants:
3957 the input video width and height
3960 same as @var{in_w} and @var{in_h}
3963 the output width and height, that is the size of the padded area as
3964 specified by the @var{width} and @var{height} expressions
3967 same as @var{out_w} and @var{out_h}
3970 x and y offsets as specified by the @var{x} and @var{y}
3971 expressions, or NAN if not yet specified
3974 same as @var{iw} / @var{ih}
3977 input sample aspect ratio
3980 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3983 horizontal and vertical chroma subsample values. For example for the
3984 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3987 @subsection Examples
3991 Add paddings with color "violet" to the input video. Output video
3992 size is 640x480, the top-left corner of the input video is placed at
3995 pad=640:480:0:40:violet
3998 The example above is equivalent to the following command:
4000 pad=width=640:height=480:x=0:y=40:color=violet
4004 Pad the input to get an output with dimensions increased by 3/2,
4005 and put the input video at the center of the padded area:
4007 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4011 Pad the input to get a squared output with size equal to the maximum
4012 value between the input width and height, and put the input video at
4013 the center of the padded area:
4015 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4019 Pad the input to get a final w/h ratio of 16:9:
4021 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4025 In case of anamorphic video, in order to set the output display aspect
4026 correctly, it is necessary to use @var{sar} in the expression,
4027 according to the relation:
4029 (ih * X / ih) * sar = output_dar
4030 X = output_dar / sar
4033 Thus the previous example needs to be modified to:
4035 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4039 Double output size and put the input video in the bottom-right
4040 corner of the output padded area:
4042 pad="2*iw:2*ih:ow-iw:oh-ih"
4046 @section pixdesctest
4048 Pixel format descriptor test filter, mainly useful for internal
4049 testing. The output video should be equal to the input video.
4053 format=monow, pixdesctest
4056 can be used to test the monowhite pixel format descriptor definition.
4060 Enable the specified chain of postprocessing subfilters using libpostproc. This
4061 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4062 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4063 Each subfilter and some options have a short and a long name that can be used
4064 interchangeably, i.e. dr/dering are the same.
4066 All subfilters share common options to determine their scope:
4070 Honor the quality commands for this subfilter.
4073 Do chrominance filtering, too (default).
4076 Do luminance filtering only (no chrominance).
4079 Do chrominance filtering only (no luminance).
4082 These options can be appended after the subfilter name, separated by a ':'.
4084 Available subfilters are:
4087 @item hb/hdeblock[:difference[:flatness]]
4088 Horizontal deblocking filter
4091 Difference factor where higher values mean more deblocking (default: @code{32}).
4093 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4096 @item vb/vdeblock[:difference[:flatness]]
4097 Vertical deblocking filter
4100 Difference factor where higher values mean more deblocking (default: @code{32}).
4102 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4105 @item ha/hadeblock[:difference[:flatness]]
4106 Accurate horizontal deblocking filter
4109 Difference factor where higher values mean more deblocking (default: @code{32}).
4111 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4114 @item va/vadeblock[:difference[:flatness]]
4115 Accurate vertical deblocking filter
4118 Difference factor where higher values mean more deblocking (default: @code{32}).
4120 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4124 The horizontal and vertical deblocking filters share the difference and
4125 flatness values so you cannot set different horizontal and vertical
4130 Experimental horizontal deblocking filter
4133 Experimental vertical deblocking filter
4138 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
4141 larger -> stronger filtering
4143 larger -> stronger filtering
4145 larger -> stronger filtering
4148 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4151 Stretch luminance to @code{0-255}.
4154 @item lb/linblenddeint
4155 Linear blend deinterlacing filter that deinterlaces the given block by
4156 filtering all lines with a @code{(1 2 1)} filter.
4158 @item li/linipoldeint
4159 Linear interpolating deinterlacing filter that deinterlaces the given block by
4160 linearly interpolating every second line.
4162 @item ci/cubicipoldeint
4163 Cubic interpolating deinterlacing filter deinterlaces the given block by
4164 cubically interpolating every second line.
4166 @item md/mediandeint
4167 Median deinterlacing filter that deinterlaces the given block by applying a
4168 median filter to every second line.
4170 @item fd/ffmpegdeint
4171 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4172 second line with a @code{(-1 4 2 4 -1)} filter.
4175 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4176 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4178 @item fq/forceQuant[:quantizer]
4179 Overrides the quantizer table from the input with the constant quantizer you
4187 Default pp filter combination (@code{hb:a,vb:a,dr:a})
4190 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
4193 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
4196 @subsection Examples
4200 Apply horizontal and vertical deblocking, deringing and automatic
4201 brightness/contrast:
4207 Apply default filters without brightness/contrast correction:
4213 Apply default filters and temporal denoiser:
4215 pp=default/tmpnoise:1:2:3
4219 Apply deblocking on luminance only, and switch vertical deblocking on or off
4220 automatically depending on available CPU time:
4228 Suppress a TV station logo, using an image file to determine which
4229 pixels comprise the logo. It works by filling in the pixels that
4230 comprise the logo with neighboring pixels.
4232 This filter requires one argument which specifies the filter bitmap
4233 file, which can be any image format supported by libavformat. The
4234 width and height of the image file must match those of the video
4235 stream being processed.
4237 Pixels in the provided bitmap image with a value of zero are not
4238 considered part of the logo, non-zero pixels are considered part of
4239 the logo. If you use white (255) for the logo and black (0) for the
4240 rest, you will be safe. For making the filter bitmap, it is
4241 recommended to take a screen capture of a black frame with the logo
4242 visible, and then using a threshold filter followed by the erode
4243 filter once or twice.
4245 If needed, little splotches can be fixed manually. Remember that if
4246 logo pixels are not covered, the filter quality will be much
4247 reduced. Marking too many pixels as part of the logo does not hurt as
4248 much, but it will increase the amount of blurring needed to cover over
4249 the image and will destroy more information than necessary, and extra
4250 pixels will slow things down on a large logo.
4254 Scale (resize) the input video, using the libswscale library.
4256 The scale filter forces the output display aspect ratio to be the same
4257 of the input, by changing the output sample aspect ratio.
4259 This filter accepts a list of named options in the form of
4260 @var{key}=@var{value} pairs separated by ":". If the key for the first
4261 two options is not specified, the assumed keys for the first two
4262 values are @code{w} and @code{h}. If the first option has no key and
4263 can be interpreted like a video size specification, it will be used
4264 to set the video size.
4266 A description of the accepted options follows.
4270 Set the video width expression, default value is @code{iw}. See below
4271 for the list of accepted constants.
4274 Set the video heiht expression, default value is @code{ih}.
4275 See below for the list of accepted constants.
4278 Set the interlacing. It accepts the following values:
4282 force interlaced aware scaling
4285 do not apply interlaced scaling
4288 select interlaced aware scaling depending on whether the source frames
4289 are flagged as interlaced or not
4292 Default value is @code{0}.
4295 Set libswscale scaling flags. If not explictly specified the filter
4296 applies a bilinear scaling algorithm.
4299 Set the video size, the value must be a valid abbreviation or in the
4300 form @var{width}x@var{height}.
4303 The values of the @var{w} and @var{h} options are expressions
4304 containing the following constants:
4308 the input width and height
4311 same as @var{in_w} and @var{in_h}
4314 the output (cropped) width and height
4317 same as @var{out_w} and @var{out_h}
4320 same as @var{iw} / @var{ih}
4323 input sample aspect ratio
4326 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4329 horizontal and vertical chroma subsample values. For example for the
4330 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4333 If the input image format is different from the format requested by
4334 the next filter, the scale filter will convert the input to the
4337 If the value for @var{width} or @var{height} is 0, the respective input
4338 size is used for the output.
4340 If the value for @var{width} or @var{height} is -1, the scale filter will
4341 use, for the respective output size, a value that maintains the aspect
4342 ratio of the input image.
4344 @subsection Examples
4348 Scale the input video to a size of 200x100:
4353 This is equivalent to:
4364 Specify a size abbreviation for the output size:
4369 which can also be written as:
4375 Scale the input to 2x:
4381 The above is the same as:
4387 Scale the input to 2x with forced interlaced scaling:
4389 scale=2*iw:2*ih:interl=1
4393 Scale the input to half size:
4399 Increase the width, and set the height to the same size:
4405 Seek for Greek harmony:
4412 Increase the height, and set the width to 3/2 of the height:
4418 Increase the size, but make the size a multiple of the chroma:
4420 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4424 Increase the width to a maximum of 500 pixels, keep the same input
4427 scale='min(500\, iw*3/2):-1'
4431 @section setdar, setsar
4433 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4436 This is done by changing the specified Sample (aka Pixel) Aspect
4437 Ratio, according to the following equation:
4439 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4442 Keep in mind that the @code{setdar} filter does not modify the pixel
4443 dimensions of the video frame. Also the display aspect ratio set by
4444 this filter may be changed by later filters in the filterchain,
4445 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4448 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4449 the filter output video.
4451 Note that as a consequence of the application of this filter, the
4452 output display aspect ratio will change according to the equation
4455 Keep in mind that the sample aspect ratio set by the @code{setsar}
4456 filter may be changed by later filters in the filterchain, e.g. if
4457 another "setsar" or a "setdar" filter is applied.
4459 The @code{setdar} and @code{setsar} filters accept a string in the
4460 form @var{num}:@var{den} expressing an aspect ratio, or the following
4461 named options, expressed as a sequence of @var{key}=@var{value} pairs,
4466 Set the maximum integer value to use for expressing numerator and
4467 denominator when reducing the expressed aspect ratio to a rational.
4468 Default value is @code{100}.
4471 Set the aspect ratio used by the filter.
4473 The parameter can be a floating point number string, an expression, or
4474 a string of the form @var{num}:@var{den}, where @var{num} and
4475 @var{den} are the numerator and denominator of the aspect ratio. If
4476 the parameter is not specified, it is assumed the value "0".
4477 In case the form "@var{num}:@var{den}" the @code{:} character should
4481 If the keys are omitted in the named options list, the specifed values
4482 are assumed to be @var{ratio} and @var{max} in that order.
4484 For example to change the display aspect ratio to 16:9, specify:
4489 The example above is equivalent to:
4494 To change the sample aspect ratio to 10:11, specify:
4499 To set a display aspect ratio of 16:9, and specify a maximum integer value of
4500 1000 in the aspect ratio reduction, use the command:
4502 setdar=ratio='16:9':max=1000
4507 Force field for the output video frame.
4509 The @code{setfield} filter marks the interlace type field for the
4510 output frames. It does not change the input frame, but only sets the
4511 corresponding property, which affects how the frame is treated by
4512 following filters (e.g. @code{fieldorder} or @code{yadif}).
4514 This filter accepts a single option @option{mode}, which can be
4515 specified either by setting @code{mode=VALUE} or setting the value
4516 alone. Available values are:
4520 Keep the same field property.
4523 Mark the frame as bottom-field-first.
4526 Mark the frame as top-field-first.
4529 Mark the frame as progressive.
4534 Show a line containing various information for each input video frame.
4535 The input video is not modified.
4537 The shown line contains a sequence of key/value pairs of the form
4538 @var{key}:@var{value}.
4540 A description of each shown parameter follows:
4544 sequential number of the input frame, starting from 0
4547 Presentation TimeStamp of the input frame, expressed as a number of
4548 time base units. The time base unit depends on the filter input pad.
4551 Presentation TimeStamp of the input frame, expressed as a number of
4555 position of the frame in the input stream, -1 if this information in
4556 unavailable and/or meaningless (for example in case of synthetic video)
4562 sample aspect ratio of the input frame, expressed in the form
4566 size of the input frame, expressed in the form
4567 @var{width}x@var{height}
4570 interlaced mode ("P" for "progressive", "T" for top field first, "B"
4571 for bottom field first)
4574 1 if the frame is a key frame, 0 otherwise
4577 picture type of the input frame ("I" for an I-frame, "P" for a
4578 P-frame, "B" for a B-frame, "?" for unknown type).
4579 Check also the documentation of the @code{AVPictureType} enum and of
4580 the @code{av_get_picture_type_char} function defined in
4581 @file{libavutil/avutil.h}.
4584 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
4586 @item plane_checksum
4587 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
4588 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
4593 Blur the input video without impacting the outlines.
4595 The filter accepts the following parameters:
4596 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
4598 Parameters prefixed by @var{luma} indicate that they work on the
4599 luminance of the pixels whereas parameters prefixed by @var{chroma}
4600 refer to the chrominance of the pixels.
4602 If the chroma parameters are not set, the luma parameters are used for
4603 either the luminance and the chrominance of the pixels.
4605 @var{luma_radius} or @var{chroma_radius} must be a float number in the
4606 range [0.1,5.0] that specifies the variance of the gaussian filter
4607 used to blur the image (slower if larger).
4609 @var{luma_strength} or @var{chroma_strength} must be a float number in
4610 the range [-1.0,1.0] that configures the blurring. A value included in
4611 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
4612 will sharpen the image.
4614 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
4615 the range [-30,30] that is used as a coefficient to determine whether
4616 a pixel should be blurred or not. A value of 0 will filter all the
4617 image, a value included in [0,30] will filter flat areas and a value
4618 included in [-30,0] will filter edges.
4623 Draw subtitles on top of input video using the libass library.
4625 To enable compilation of this filter you need to configure FFmpeg with
4626 @code{--enable-libass}. This filter also requires a build with libavcodec and
4627 libavformat to convert the passed subtitles file to ASS (Advanced Substation
4628 Alpha) subtitles format.
4630 This filter accepts the following named options, expressed as a
4631 sequence of @var{key}=@var{value} pairs, separated by ":".
4635 Set the filename of the subtitle file to read. It must be specified.
4638 Specify the size of the original video, the video for which the ASS file
4639 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
4640 necessary to correctly scale the fonts if the aspect ratio has been changed.
4643 If the first key is not specified, it is assumed that the first value
4644 specifies the @option{filename}.
4646 For example, to render the file @file{sub.srt} on top of the input
4647 video, use the command:
4652 which is equivalent to:
4654 subtitles=filename=sub.srt
4659 Split input video into several identical outputs.
4661 The filter accepts a single parameter which specifies the number of outputs. If
4662 unspecified, it defaults to 2.
4666 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
4668 will create 5 copies of the input video.
4672 [in] split [splitout1][splitout2];
4673 [splitout1] crop=100:100:0:0 [cropout];
4674 [splitout2] pad=200:200:100:100 [padout];
4677 will create two separate outputs from the same input, one cropped and
4682 Scale the input by 2x and smooth using the Super2xSaI (Scale and
4683 Interpolate) pixel art scaling algorithm.
4685 Useful for enlarging pixel art images without reducing sharpness.
4691 Select the most representative frame in a given sequence of consecutive frames.
4693 It accepts as argument the frames batch size to analyze (default @var{N}=100);
4694 in a set of @var{N} frames, the filter will pick one of them, and then handle
4695 the next batch of @var{N} frames until the end.
4697 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
4698 value will result in a higher memory usage, so a high value is not recommended.
4700 The following example extract one picture each 50 frames:
4705 Complete example of a thumbnail creation with @command{ffmpeg}:
4707 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
4712 Tile several successive frames together.
4714 It accepts a list of options in the form of @var{key}=@var{value} pairs
4715 separated by ":". A description of the accepted options follows.
4720 Set the grid size (i.e. the number of lines and columns) in the form
4724 Set the outer border margin in pixels.
4727 Set the inner border thickness (i.e. the number of pixels between frames). For
4728 more advanced padding options (such as having different values for the edges),
4729 refer to the pad video filter.
4732 Set the maximum number of frames to render in the given area. It must be less
4733 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
4734 the area will be used.
4738 Alternatively, the options can be specified as a flat string:
4740 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
4742 For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
4745 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
4747 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
4748 duplicating each output frame to accomodate the originally detected frame
4751 Another example to display @code{5} pictures in an area of @code{3x2} frames,
4752 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
4753 mixed flat and named options:
4755 tile=3x2:nb_frames=5:padding=7:margin=2
4760 Perform various types of temporal field interlacing.
4762 Frames are counted starting from 1, so the first input frame is
4765 This filter accepts options in the form of @var{key}=@var{value} pairs
4767 Alternatively, the @var{mode} option can be specified as a value alone,
4768 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
4771 A description of the accepted options follows.
4776 Specify the mode of the interlacing. This option can also be specified
4777 as a value alone. See below for a list of values for this option.
4779 Available values are:
4783 Move odd frames into the upper field, even into the lower field,
4784 generating a double height frame at half framerate.
4787 Only output even frames, odd frames are dropped, generating a frame with
4788 unchanged height at half framerate.
4791 Only output odd frames, even frames are dropped, generating a frame with
4792 unchanged height at half framerate.
4795 Expand each frame to full height, but pad alternate lines with black,
4796 generating a frame with double height at the same input framerate.
4798 @item interleave_top, 4
4799 Interleave the upper field from odd frames with the lower field from
4800 even frames, generating a frame with unchanged height at half framerate.
4802 @item interleave_bottom, 5
4803 Interleave the lower field from odd frames with the upper field from
4804 even frames, generating a frame with unchanged height at half framerate.
4806 @item interlacex2, 6
4807 Double frame rate with unchanged height. Frames are inserted each
4808 containing the second temporal field from the previous input frame and
4809 the first temporal field from the next input frame. This mode relies on
4810 the top_field_first flag. Useful for interlaced video displays with no
4811 field synchronisation.
4814 Numeric values are deprecated but are accepted for backward
4815 compatibility reasons.
4817 Default mode is @code{merge}.
4820 Specify flags influencing the filter process.
4822 Available value for @var{flags} is:
4825 @item low_pass_filter, vlfp
4826 Enable vertical low-pass filtering in the filter.
4827 Vertical low-pass filtering is required when creating an interlaced
4828 destination from a progressive source which contains high-frequency
4829 vertical detail. Filtering will reduce interlace 'twitter' and Moire
4832 Vertical low-pass filtering can only be enabled for @option{mode}
4833 @var{interleave_top} and @var{interleave_bottom}.
4840 Transpose rows with columns in the input video and optionally flip it.
4842 The filter accepts parameters as a list of @var{key}=@var{value}
4843 pairs, separated by ':'. If the key of the first options is omitted,
4844 the arguments are interpreted according to the syntax
4845 @var{dir}:@var{passthrough}.
4849 Specify the transposition direction. Can assume the following values:
4853 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
4861 Rotate by 90 degrees clockwise, that is:
4869 Rotate by 90 degrees counterclockwise, that is:
4877 Rotate by 90 degrees clockwise and vertically flip, that is:
4885 For values between 4-7, the transposition is only done if the input
4886 video geometry is portrait and not landscape. These values are
4887 deprecated, the @code{passthrough} option should be used instead.
4890 Do not apply the transposition if the input geometry matches the one
4891 specified by the specified value. It accepts the following values:
4894 Always apply transposition.
4896 Preserve portrait geometry (when @var{height} >= @var{width}).
4898 Preserve landscape geometry (when @var{width} >= @var{height}).
4901 Default value is @code{none}.
4904 For example to rotate by 90 degrees clockwise and preserve portrait
4907 transpose=dir=1:passthrough=portrait
4910 The command above can also be specified as:
4912 transpose=1:portrait
4917 Sharpen or blur the input video.
4919 It accepts the following parameters:
4920 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
4922 Negative values for the amount will blur the input video, while positive
4923 values will sharpen. All parameters are optional and default to the
4924 equivalent of the string '5:5:1.0:5:5:0.0'.
4929 Set the luma matrix horizontal size. It can be an integer between 3
4930 and 13, default value is 5.
4933 Set the luma matrix vertical size. It can be an integer between 3
4934 and 13, default value is 5.
4937 Set the luma effect strength. It can be a float number between -2.0
4938 and 5.0, default value is 1.0.
4940 @item chroma_msize_x
4941 Set the chroma matrix horizontal size. It can be an integer between 3
4942 and 13, default value is 5.
4944 @item chroma_msize_y
4945 Set the chroma matrix vertical size. It can be an integer between 3
4946 and 13, default value is 5.
4949 Set the chroma effect strength. It can be a float number between -2.0
4950 and 5.0, default value is 0.0.
4955 # Strong luma sharpen effect parameters
4958 # Strong blur of both luma and chroma parameters
4959 unsharp=7:7:-2:7:7:-2
4961 # Use the default values with @command{ffmpeg}
4962 ffmpeg -i in.avi -vf "unsharp" out.mp4
4967 Flip the input video vertically.
4970 ffmpeg -i in.avi -vf "vflip" out.avi
4975 Deinterlace the input video ("yadif" means "yet another deinterlacing
4978 The filter accepts parameters as a list of @var{key}=@var{value}
4979 pairs, separated by ":". If the key of the first options is omitted,
4980 the arguments are interpreted according to syntax
4981 @var{mode}:@var{parity}:@var{deint}.
4983 The description of the accepted parameters follows.
4987 Specify the interlacing mode to adopt. Accept one of the following
4992 output 1 frame for each frame
4994 output 1 frame for each field
4995 @item 2, send_frame_nospatial
4996 like @code{send_frame} but skip spatial interlacing check
4997 @item 3, send_field_nospatial
4998 like @code{send_field} but skip spatial interlacing check
5001 Default value is @code{send_frame}.
5004 Specify the picture field parity assumed for the input interlaced
5005 video. Accept one of the following values:
5009 assume top field first
5011 assume bottom field first
5013 enable automatic detection
5016 Default value is @code{auto}.
5017 If interlacing is unknown or decoder does not export this information,
5018 top field first will be assumed.
5021 Specify which frames to deinterlace. Accept one of the following
5026 deinterlace all frames
5028 only deinterlace frames marked as interlaced
5031 Default value is @code{all}.
5034 @c man end VIDEO FILTERS
5036 @chapter Video Sources
5037 @c man begin VIDEO SOURCES
5039 Below is a description of the currently available video sources.
5043 Buffer video frames, and make them available to the filter chain.
5045 This source is mainly intended for a programmatic use, in particular
5046 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5048 It accepts a list of options in the form of @var{key}=@var{value} pairs
5049 separated by ":". A description of the accepted options follows.
5054 Specify the size (width and height) of the buffered video frames.
5057 A string representing the pixel format of the buffered video frames.
5058 It may be a number corresponding to a pixel format, or a pixel format
5062 Specify the timebase assumed by the timestamps of the buffered frames.
5065 Specify the frame rate expected for the video stream.
5068 Specify the sample aspect ratio assumed by the video frames.
5071 Specify the optional parameters to be used for the scale filter which
5072 is automatically inserted when an input change is detected in the
5073 input size or format.
5078 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5081 will instruct the source to accept video frames with size 320x240 and
5082 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5083 square pixels (1:1 sample aspect ratio).
5084 Since the pixel format with name "yuv410p" corresponds to the number 6
5085 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5086 this example corresponds to:
5088 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5091 Alternatively, the options can be specified as a flat string, but this
5092 syntax is deprecated:
5094 @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}]
5098 Create a pattern generated by an elementary cellular automaton.
5100 The initial state of the cellular automaton can be defined through the
5101 @option{filename}, and @option{pattern} options. If such options are
5102 not specified an initial state is created randomly.
5104 At each new frame a new row in the video is filled with the result of
5105 the cellular automaton next generation. The behavior when the whole
5106 frame is filled is defined by the @option{scroll} option.
5108 This source accepts a list of options in the form of
5109 @var{key}=@var{value} pairs separated by ":". A description of the
5110 accepted options follows.
5114 Read the initial cellular automaton state, i.e. the starting row, from
5116 In the file, each non-whitespace character is considered an alive
5117 cell, a newline will terminate the row, and further characters in the
5118 file will be ignored.
5121 Read the initial cellular automaton state, i.e. the starting row, from
5122 the specified string.
5124 Each non-whitespace character in the string is considered an alive
5125 cell, a newline will terminate the row, and further characters in the
5126 string will be ignored.
5129 Set the video rate, that is the number of frames generated per second.
5132 @item random_fill_ratio, ratio
5133 Set the random fill ratio for the initial cellular automaton row. It
5134 is a floating point number value ranging from 0 to 1, defaults to
5137 This option is ignored when a file or a pattern is specified.
5139 @item random_seed, seed
5140 Set the seed for filling randomly the initial row, must be an integer
5141 included between 0 and UINT32_MAX. If not specified, or if explicitly
5142 set to -1, the filter will try to use a good random seed on a best
5146 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5147 Default value is 110.
5150 Set the size of the output video.
5152 If @option{filename} or @option{pattern} is specified, the size is set
5153 by default to the width of the specified initial state row, and the
5154 height is set to @var{width} * PHI.
5156 If @option{size} is set, it must contain the width of the specified
5157 pattern string, and the specified pattern will be centered in the
5160 If a filename or a pattern string is not specified, the size value
5161 defaults to "320x518" (used for a randomly generated initial state).
5164 If set to 1, scroll the output upward when all the rows in the output
5165 have been already filled. If set to 0, the new generated row will be
5166 written over the top row just after the bottom row is filled.
5169 @item start_full, full
5170 If set to 1, completely fill the output with generated rows before
5171 outputting the first frame.
5172 This is the default behavior, for disabling set the value to 0.
5175 If set to 1, stitch the left and right row edges together.
5176 This is the default behavior, for disabling set the value to 0.
5179 @subsection Examples
5183 Read the initial state from @file{pattern}, and specify an output of
5186 cellauto=f=pattern:s=200x400
5190 Generate a random initial row with a width of 200 cells, with a fill
5193 cellauto=ratio=2/3:s=200x200
5197 Create a pattern generated by rule 18 starting by a single alive cell
5198 centered on an initial row with width 100:
5200 cellauto=p=@@:s=100x400:full=0:rule=18
5204 Specify a more elaborated initial pattern:
5206 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5213 Generate a Mandelbrot set fractal, and progressively zoom towards the
5214 point specified with @var{start_x} and @var{start_y}.
5216 This source accepts a list of options in the form of
5217 @var{key}=@var{value} pairs separated by ":". A description of the
5218 accepted options follows.
5223 Set the terminal pts value. Default value is 400.
5226 Set the terminal scale value.
5227 Must be a floating point value. Default value is 0.3.
5230 Set the inner coloring mode, that is the algorithm used to draw the
5231 Mandelbrot fractal internal region.
5233 It shall assume one of the following values:
5238 Show time until convergence.
5240 Set color based on point closest to the origin of the iterations.
5245 Default value is @var{mincol}.
5248 Set the bailout value. Default value is 10.0.
5251 Set the maximum of iterations performed by the rendering
5252 algorithm. Default value is 7189.
5255 Set outer coloring mode.
5256 It shall assume one of following values:
5258 @item iteration_count
5259 Set iteration cound mode.
5260 @item normalized_iteration_count
5261 set normalized iteration count mode.
5263 Default value is @var{normalized_iteration_count}.
5266 Set frame rate, expressed as number of frames per second. Default
5270 Set frame size. Default value is "640x480".
5273 Set the initial scale value. Default value is 3.0.
5276 Set the initial x position. Must be a floating point value between
5277 -100 and 100. Default value is -0.743643887037158704752191506114774.
5280 Set the initial y position. Must be a floating point value between
5281 -100 and 100. Default value is -0.131825904205311970493132056385139.
5286 Generate various test patterns, as generated by the MPlayer test filter.
5288 The size of the generated video is fixed, and is 256x256.
5289 This source is useful in particular for testing encoding features.
5291 This source accepts an optional sequence of @var{key}=@var{value} pairs,
5292 separated by ":". The description of the accepted options follows.
5297 Specify the frame rate of the sourced video, as the number of frames
5298 generated per second. It has to be a string in the format
5299 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5300 number or a valid video frame rate abbreviation. The default value is
5304 Set the video duration of the sourced video. The accepted syntax is:
5309 See also the function @code{av_parse_time()}.
5311 If not specified, or the expressed duration is negative, the video is
5312 supposed to be generated forever.
5316 Set the number or the name of the test to perform. Supported tests are:
5331 Default value is "all", which will cycle through the list of all tests.
5334 For example the following:
5339 will generate a "dc_luma" test pattern.
5343 Provide a frei0r source.
5345 To enable compilation of this filter you need to install the frei0r
5346 header and configure FFmpeg with @code{--enable-frei0r}.
5348 The source supports the syntax:
5350 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
5353 @var{size} is the size of the video to generate, may be a string of the
5354 form @var{width}x@var{height} or a frame size abbreviation.
5355 @var{rate} is the rate of the video to generate, may be a string of
5356 the form @var{num}/@var{den} or a frame rate abbreviation.
5357 @var{src_name} is the name to the frei0r source to load. For more
5358 information regarding frei0r and how to set the parameters read the
5359 section @ref{frei0r} in the description of the video filters.
5361 For example, to generate a frei0r partik0l source with size 200x200
5362 and frame rate 10 which is overlayed on the overlay filter main input:
5364 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
5369 Generate a life pattern.
5371 This source is based on a generalization of John Conway's life game.
5373 The sourced input represents a life grid, each pixel represents a cell
5374 which can be in one of two possible states, alive or dead. Every cell
5375 interacts with its eight neighbours, which are the cells that are
5376 horizontally, vertically, or diagonally adjacent.
5378 At each interaction the grid evolves according to the adopted rule,
5379 which specifies the number of neighbor alive cells which will make a
5380 cell stay alive or born. The @option{rule} option allows to specify
5383 This source accepts a list of options in the form of
5384 @var{key}=@var{value} pairs separated by ":". A description of the
5385 accepted options follows.
5389 Set the file from which to read the initial grid state. In the file,
5390 each non-whitespace character is considered an alive cell, and newline
5391 is used to delimit the end of each row.
5393 If this option is not specified, the initial grid is generated
5397 Set the video rate, that is the number of frames generated per second.
5400 @item random_fill_ratio, ratio
5401 Set the random fill ratio for the initial random grid. It is a
5402 floating point number value ranging from 0 to 1, defaults to 1/PHI.
5403 It is ignored when a file is specified.
5405 @item random_seed, seed
5406 Set the seed for filling the initial random grid, must be an integer
5407 included between 0 and UINT32_MAX. If not specified, or if explicitly
5408 set to -1, the filter will try to use a good random seed on a best
5414 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
5415 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
5416 @var{NS} specifies the number of alive neighbor cells which make a
5417 live cell stay alive, and @var{NB} the number of alive neighbor cells
5418 which make a dead cell to become alive (i.e. to "born").
5419 "s" and "b" can be used in place of "S" and "B", respectively.
5421 Alternatively a rule can be specified by an 18-bits integer. The 9
5422 high order bits are used to encode the next cell state if it is alive
5423 for each number of neighbor alive cells, the low order bits specify
5424 the rule for "borning" new cells. Higher order bits encode for an
5425 higher number of neighbor cells.
5426 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
5427 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
5429 Default value is "S23/B3", which is the original Conway's game of life
5430 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
5431 cells, and will born a new cell if there are three alive cells around
5435 Set the size of the output video.
5437 If @option{filename} is specified, the size is set by default to the
5438 same size of the input file. If @option{size} is set, it must contain
5439 the size specified in the input file, and the initial grid defined in
5440 that file is centered in the larger resulting area.
5442 If a filename is not specified, the size value defaults to "320x240"
5443 (used for a randomly generated initial grid).
5446 If set to 1, stitch the left and right grid edges together, and the
5447 top and bottom edges also. Defaults to 1.
5450 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
5451 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
5452 value from 0 to 255.
5455 Set the color of living (or new born) cells.
5458 Set the color of dead cells. If @option{mold} is set, this is the first color
5459 used to represent a dead cell.
5462 Set mold color, for definitely dead and moldy cells.
5465 @subsection Examples
5469 Read a grid from @file{pattern}, and center it on a grid of size
5472 life=f=pattern:s=300x300
5476 Generate a random grid of size 200x200, with a fill ratio of 2/3:
5478 life=ratio=2/3:s=200x200
5482 Specify a custom rule for evolving a randomly generated grid:
5488 Full example with slow death effect (mold) using @command{ffplay}:
5490 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
5494 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
5496 The @code{color} source provides an uniformly colored input.
5498 The @code{nullsrc} source returns unprocessed video frames. It is
5499 mainly useful to be employed in analysis / debugging tools, or as the
5500 source for filters which ignore the input data.
5502 The @code{rgbtestsrc} source generates an RGB test pattern useful for
5503 detecting RGB vs BGR issues. You should see a red, green and blue
5504 stripe from top to bottom.
5506 The @code{smptebars} source generates a color bars pattern, based on
5507 the SMPTE Engineering Guideline EG 1-1990.
5509 The @code{testsrc} source generates a test video pattern, showing a
5510 color pattern, a scrolling gradient and a timestamp. This is mainly
5511 intended for testing purposes.
5513 These sources accept an optional sequence of @var{key}=@var{value} pairs,
5514 separated by ":". The description of the accepted options follows.
5519 Specify the color of the source, only used in the @code{color}
5520 source. It can be the name of a color (case insensitive match) or a
5521 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
5522 default value is "black".
5525 Specify the size of the sourced video, it may be a string of the form
5526 @var{width}x@var{height}, or the name of a size abbreviation. The
5527 default value is "320x240".
5530 Specify the frame rate of the sourced video, as the number of frames
5531 generated per second. It has to be a string in the format
5532 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5533 number or a valid video frame rate abbreviation. The default value is
5537 Set the sample aspect ratio of the sourced video.
5540 Set the video duration of the sourced video. The accepted syntax is:
5542 [-]HH[:MM[:SS[.m...]]]
5545 See also the function @code{av_parse_time()}.
5547 If not specified, or the expressed duration is negative, the video is
5548 supposed to be generated forever.
5551 Set the number of decimals to show in the timestamp, only used in the
5552 @code{testsrc} source.
5554 The displayed timestamp value will correspond to the original
5555 timestamp value multiplied by the power of 10 of the specified
5556 value. Default value is 0.
5559 For example the following:
5561 testsrc=duration=5.3:size=qcif:rate=10
5564 will generate a video with a duration of 5.3 seconds, with size
5565 176x144 and a frame rate of 10 frames per second.
5567 The following graph description will generate a red source
5568 with an opacity of 0.2, with size "qcif" and a frame rate of 10
5571 color=c=red@@0.2:s=qcif:r=10
5574 If the input content is to be ignored, @code{nullsrc} can be used. The
5575 following command generates noise in the luminance plane by employing
5576 the @code{geq} filter:
5578 nullsrc=s=256x256, geq=random(1)*255:128:128
5581 @c man end VIDEO SOURCES
5583 @chapter Video Sinks
5584 @c man begin VIDEO SINKS
5586 Below is a description of the currently available video sinks.
5590 Buffer video frames, and make them available to the end of the filter
5593 This sink is mainly intended for a programmatic use, in particular
5594 through the interface defined in @file{libavfilter/buffersink.h}.
5596 It does not require a string parameter in input, but you need to
5597 specify a pointer to a list of supported pixel formats terminated by
5598 -1 in the opaque parameter provided to @code{avfilter_init_filter}
5599 when initializing this sink.
5603 Null video sink, do absolutely nothing with the input video. It is
5604 mainly useful as a template and to be employed in analysis / debugging
5607 @c man end VIDEO SINKS
5609 @chapter Multimedia Filters
5610 @c man begin MULTIMEDIA FILTERS
5612 Below is a description of the currently available multimedia filters.
5614 @section aselect, select
5615 Select frames to pass in output.
5617 These filters accept a single option @option{expr} or @option{e}
5618 specifying the select expression, which can be specified either by
5619 specyfing @code{expr=VALUE} or specifying the expression
5622 The select expression is evaluated for each input frame. If the
5623 evaluation result is a non-zero value, the frame is selected and
5624 passed to the output, otherwise it is discarded.
5626 The expression can contain the following constants:
5630 the sequential number of the filtered frame, starting from 0
5633 the sequential number of the selected frame, starting from 0
5635 @item prev_selected_n
5636 the sequential number of the last selected frame, NAN if undefined
5639 timebase of the input timestamps
5642 the PTS (Presentation TimeStamp) of the filtered video frame,
5643 expressed in @var{TB} units, NAN if undefined
5646 the PTS (Presentation TimeStamp) of the filtered video frame,
5647 expressed in seconds, NAN if undefined
5650 the PTS of the previously filtered video frame, NAN if undefined
5652 @item prev_selected_pts
5653 the PTS of the last previously filtered video frame, NAN if undefined
5655 @item prev_selected_t
5656 the PTS of the last previously selected video frame, NAN if undefined
5659 the PTS of the first video frame in the video, NAN if undefined
5662 the time of the first video frame in the video, NAN if undefined
5664 @item pict_type @emph{(video only)}
5665 the type of the filtered frame, can assume one of the following
5677 @item interlace_type @emph{(video only)}
5678 the frame interlace type, can assume one of the following values:
5681 the frame is progressive (not interlaced)
5683 the frame is top-field-first
5685 the frame is bottom-field-first
5688 @item consumed_sample_n @emph{(audio only)}
5689 the number of selected samples before the current frame
5691 @item samples_n @emph{(audio only)}
5692 the number of samples in the current frame
5694 @item sample_rate @emph{(audio only)}
5695 the input sample rate
5698 1 if the filtered frame is a key-frame, 0 otherwise
5701 the position in the file of the filtered frame, -1 if the information
5702 is not available (e.g. for synthetic video)
5704 @item scene @emph{(video only)}
5705 value between 0 and 1 to indicate a new scene; a low value reflects a low
5706 probability for the current frame to introduce a new scene, while a higher
5707 value means the current frame is more likely to be one (see the example below)
5711 The default value of the select expression is "1".
5713 @subsection Examples
5717 Select all frames in input:
5722 The example above is the same as:
5734 Select only I-frames:
5736 select='eq(pict_type\,I)'
5740 Select one frame every 100:
5742 select='not(mod(n\,100))'
5746 Select only frames contained in the 10-20 time interval:
5748 select='gte(t\,10)*lte(t\,20)'
5752 Select only I frames contained in the 10-20 time interval:
5754 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
5758 Select frames with a minimum distance of 10 seconds:
5760 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
5764 Use aselect to select only audio frames with samples number > 100:
5766 aselect='gt(samples_n\,100)'
5770 Create a mosaic of the first scenes:
5772 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
5775 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
5779 @section asendcmd, sendcmd
5781 Send commands to filters in the filtergraph.
5783 These filters read commands to be sent to other filters in the
5786 @code{asendcmd} must be inserted between two audio filters,
5787 @code{sendcmd} must be inserted between two video filters, but apart
5788 from that they act the same way.
5790 The specification of commands can be provided in the filter arguments
5791 with the @var{commands} option, or in a file specified by the
5792 @var{filename} option.
5794 These filters accept the following options:
5797 Set the commands to be read and sent to the other filters.
5799 Set the filename of the commands to be read and sent to the other
5803 @subsection Commands syntax
5805 A commands description consists of a sequence of interval
5806 specifications, comprising a list of commands to be executed when a
5807 particular event related to that interval occurs. The occurring event
5808 is typically the current frame time entering or leaving a given time
5811 An interval is specified by the following syntax:
5813 @var{START}[-@var{END}] @var{COMMANDS};
5816 The time interval is specified by the @var{START} and @var{END} times.
5817 @var{END} is optional and defaults to the maximum time.
5819 The current frame time is considered within the specified interval if
5820 it is included in the interval [@var{START}, @var{END}), that is when
5821 the time is greater or equal to @var{START} and is lesser than
5824 @var{COMMANDS} consists of a sequence of one or more command
5825 specifications, separated by ",", relating to that interval. The
5826 syntax of a command specification is given by:
5828 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
5831 @var{FLAGS} is optional and specifies the type of events relating to
5832 the time interval which enable sending the specified command, and must
5833 be a non-null sequence of identifier flags separated by "+" or "|" and
5834 enclosed between "[" and "]".
5836 The following flags are recognized:
5839 The command is sent when the current frame timestamp enters the
5840 specified interval. In other words, the command is sent when the
5841 previous frame timestamp was not in the given interval, and the
5845 The command is sent when the current frame timestamp leaves the
5846 specified interval. In other words, the command is sent when the
5847 previous frame timestamp was in the given interval, and the
5851 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
5854 @var{TARGET} specifies the target of the command, usually the name of
5855 the filter class or a specific filter instance name.
5857 @var{COMMAND} specifies the name of the command for the target filter.
5859 @var{ARG} is optional and specifies the optional list of argument for
5860 the given @var{COMMAND}.
5862 Between one interval specification and another, whitespaces, or
5863 sequences of characters starting with @code{#} until the end of line,
5864 are ignored and can be used to annotate comments.
5866 A simplified BNF description of the commands specification syntax
5869 @var{COMMAND_FLAG} ::= "enter" | "leave"
5870 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
5871 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
5872 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
5873 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
5874 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
5877 @subsection Examples
5881 Specify audio tempo change at second 4:
5883 asendcmd=c='4.0 atempo tempo 1.5',atempo
5887 Specify a list of drawtext and hue commands in a file.
5889 # show text in the interval 5-10
5890 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
5891 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
5893 # desaturate the image in the interval 15-20
5894 15.0-20.0 [enter] hue reinit s=0,
5895 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
5896 [leave] hue reinit s=1,
5897 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
5899 # apply an exponential saturation fade-out effect, starting from time 25
5900 25 [enter] hue s=exp(t-25)
5903 A filtergraph allowing to read and process the above command list
5904 stored in a file @file{test.cmd}, can be specified with:
5906 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
5911 @section asetpts, setpts
5913 Change the PTS (presentation timestamp) of the input frames.
5915 @code{asetpts} works on audio frames, @code{setpts} on video frames.
5917 Accept in input an expression evaluated through the eval API, which
5918 can contain the following constants:
5922 frame rate, only defined for constant frame-rate video
5925 the presentation timestamp in input
5928 the count of the input frame, starting from 0.
5930 @item NB_CONSUMED_SAMPLES
5931 the number of consumed samples, not including the current frame (only
5935 the number of samples in the current frame (only audio)
5941 the PTS of the first frame
5944 the time in seconds of the first frame
5947 tell if the current frame is interlaced
5950 the time in seconds of the current frame
5956 original position in the file of the frame, or undefined if undefined
5957 for the current frame
5963 previous input time in seconds
5969 previous output time in seconds
5972 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
5976 wallclock (RTC) time at the start of the movie in microseconds
5979 @subsection Examples
5983 Start counting PTS from zero
5989 Apply fast motion effect:
5995 Apply slow motion effect:
6001 Set fixed rate of 25 frames per second:
6007 Set fixed rate 25 fps with some jitter:
6009 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6013 Apply an offset of 10 seconds to the input PTS:
6019 Generate timestamps from a "live source" and rebase onto the current timebase:
6021 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6027 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6028 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6029 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6030 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6032 The filter also has a video output (see the @var{video} option) with a real
6033 time graph to observe the loudness evolution. The graphic contains the logged
6034 message mentioned above, so it is not printed anymore when this option is set,
6035 unless the verbose logging is set. The main graphing area contains the
6036 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6037 the momentary loudness (400 milliseconds).
6039 More information about the Loudness Recommendation EBU R128 on
6040 @url{http://tech.ebu.ch/loudness}.
6042 The filter accepts the following named parameters:
6047 Activate the video output. The audio stream is passed unchanged whether this
6048 option is set or no. The video stream will be the first output stream if
6049 activated. Default is @code{0}.
6052 Set the video size. This option is for video only. Default and minimum
6053 resolution is @code{640x480}.
6056 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6057 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6058 other integer value between this range is allowed.
6062 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
6064 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6067 Run an analysis with @command{ffmpeg}:
6069 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6072 @section settb, asettb
6074 Set the timebase to use for the output frames timestamps.
6075 It is mainly useful for testing timebase configuration.
6077 It accepts in input an arithmetic expression representing a rational.
6078 The expression can contain the constants "AVTB" (the
6079 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
6082 The default value for the input is "intb".
6084 @subsection Examples
6088 Set the timebase to 1/25:
6094 Set the timebase to 1/10:
6100 Set the timebase to 1001/1000:
6106 Set the timebase to 2*intb:
6112 Set the default timebase value:
6120 Concatenate audio and video streams, joining them together one after the
6123 The filter works on segments of synchronized video and audio streams. All
6124 segments must have the same number of streams of each type, and that will
6125 also be the number of streams at output.
6127 The filter accepts the following named parameters:
6131 Set the number of segments. Default is 2.
6134 Set the number of output video streams, that is also the number of video
6135 streams in each segment. Default is 1.
6138 Set the number of output audio streams, that is also the number of video
6139 streams in each segment. Default is 0.
6142 Activate unsafe mode: do not fail if segments have a different format.
6146 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6147 @var{a} audio outputs.
6149 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6150 segment, in the same order as the outputs, then the inputs for the second
6153 Related streams do not always have exactly the same duration, for various
6154 reasons including codec frame size or sloppy authoring. For that reason,
6155 related synchronized streams (e.g. a video and its audio track) should be
6156 concatenated at once. The concat filter will use the duration of the longest
6157 stream in each segment (except the last one), and if necessary pad shorter
6158 audio streams with silence.
6160 For this filter to work correctly, all segments must start at timestamp 0.
6162 All corresponding streams must have the same parameters in all segments; the
6163 filtering system will automatically select a common pixel format for video
6164 streams, and a common sample format, sample rate and channel layout for
6165 audio streams, but other settings, such as resolution, must be converted
6166 explicitly by the user.
6168 Different frame rates are acceptable but will result in variable frame rate
6169 at output; be sure to configure the output file to handle it.
6174 Concatenate an opening, an episode and an ending, all in bilingual version
6175 (video in stream 0, audio in streams 1 and 2):
6177 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6178 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6179 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6180 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6184 Concatenate two parts, handling audio and video separately, using the
6185 (a)movie sources, and adjusting the resolution:
6187 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6188 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6189 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
6191 Note that a desync will happen at the stitch if the audio and video streams
6192 do not have exactly the same duration in the first file.
6196 @section showspectrum
6198 Convert input audio to a video output, representing the audio frequency
6201 The filter accepts the following named parameters:
6204 Specify the video size for the output. Default value is @code{640x512}.
6207 Specify if the spectrum should slide along the window. Default value is
6211 Specify display mode.
6213 It accepts the following values:
6216 all channels are displayed in the same row
6218 all channels are displayed in separate rows
6221 Default value is @samp{combined}.
6224 Specify display color mode.
6226 It accepts the following values:
6229 each channel is displayed in a separate color
6231 each channel is is displayed using the same color scheme
6234 Default value is @samp{channel}.
6237 Specify scale used for calculating intensity color values.
6239 It accepts the following values:
6244 square root, default
6251 Default value is @samp{sqrt}.
6254 Set saturation modifier for displayed colors. Negative values provide
6255 alternative color scheme. @code{0} is no saturation at all.
6256 Saturation must be in [-10.0, 10.0] range.
6257 Default value is @code{1}.
6260 The usage is very similar to the showwaves filter; see the examples in that
6265 Convert input audio to a video output, representing the samples waves.
6267 The filter accepts the following named parameters:
6272 Available values are:
6275 Draw a point for each sample.
6278 Draw a vertical line for each sample.
6281 Default value is @code{point}.
6284 Set the number of samples which are printed on the same column. A
6285 larger value will decrease the frame rate. Must be a positive
6286 integer. This option can be set only if the value for @var{rate}
6287 is not explicitly specified.
6290 Set the (approximate) output frame rate. This is done by setting the
6291 option @var{n}. Default value is "25".
6294 Specify the video size for the output. Default value is "600x240".
6297 Some examples follow.
6300 Output the input file audio and the corresponding video representation
6303 amovie=a.mp3,asplit[out0],showwaves[out1]
6307 Create a synthetic signal and show it with showwaves, forcing a
6308 framerate of 30 frames per second:
6310 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
6314 @c man end MULTIMEDIA FILTERS
6316 @chapter Multimedia Sources
6317 @c man begin MULTIMEDIA SOURCES
6319 Below is a description of the currently available multimedia sources.
6323 This is the same as @ref{movie} source, except it selects an audio
6329 Read audio and/or video stream(s) from a movie container.
6331 It accepts the syntax: @var{movie_name}[:@var{options}] where
6332 @var{movie_name} is the name of the resource to read (not necessarily
6333 a file but also a device or a stream accessed through some protocol),
6334 and @var{options} is an optional sequence of @var{key}=@var{value}
6335 pairs, separated by ":".
6337 The description of the accepted options follows.
6341 @item format_name, f
6342 Specifies the format assumed for the movie to read, and can be either
6343 the name of a container or an input device. If not specified the
6344 format is guessed from @var{movie_name} or by probing.
6346 @item seek_point, sp
6347 Specifies the seek point in seconds, the frames will be output
6348 starting from this seek point, the parameter is evaluated with
6349 @code{av_strtod} so the numerical value may be suffixed by an IS
6350 postfix. Default value is "0".
6353 Specifies the streams to read. Several streams can be specified,
6354 separated by "+". The source will then have as many outputs, in the
6355 same order. The syntax is explained in the ``Stream specifiers''
6356 section in the ffmpeg manual. Two special names, "dv" and "da" specify
6357 respectively the default (best suited) video and audio stream. Default
6358 is "dv", or "da" if the filter is called as "amovie".
6360 @item stream_index, si
6361 Specifies the index of the video stream to read. If the value is -1,
6362 the best suited video stream will be automatically selected. Default
6363 value is "-1". Deprecated. If the filter is called "amovie", it will select
6364 audio instead of video.
6367 Specifies how many times to read the stream in sequence.
6368 If the value is less than 1, the stream will be read again and again.
6369 Default value is "1".
6371 Note that when the movie is looped the source timestamps are not
6372 changed, so it will generate non monotonically increasing timestamps.
6375 This filter allows to overlay a second video on top of main input of
6376 a filtergraph as shown in this graph:
6378 input -----------> deltapts0 --> overlay --> output
6381 movie --> scale--> deltapts1 -------+
6384 Some examples follow.
6388 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
6389 on top of the input labelled as "in":
6391 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6392 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6396 Read from a video4linux2 device, and overlay it on top of the input
6399 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6400 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6404 Read the first video stream and the audio stream with id 0x81 from
6405 dvd.vob; the video is connected to the pad named "video" and the audio is
6406 connected to the pad named "audio":
6408 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
6412 @c man end MULTIMEDIA SOURCES