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{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
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 Blend two video frames into each other.
1785 It takes two input streams and outputs one stream, the first input is the
1786 "top" layer and second input is "bottom" layer.
1787 Output terminates when shortest input terminates.
1789 This filter accepts a list of options in the form of @var{key}=@var{value}
1790 pairs separated by ":". A description of the accepted options follows.
1798 Set blend mode for specific pixel component or all pixel components in case
1799 of @var{all_mode}. Default value is @code{normal}.
1801 Available values for component modes are:
1834 Set blend opacity for specific pixel component or all pixel components in case
1835 of @var{all_expr}. Only used in combination with pixel component blend modes.
1842 Set blend expression for specific pixel component or all pixel components in case
1843 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1845 The expressions can use the following variables:
1850 the coordinates of the current sample
1854 the width and height of currently filtered plane
1858 Width and height scale depending on the currently filtered plane. It is the
1859 ratio between the corresponding luma plane number of pixels and the current
1860 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1861 @code{0.5,0.5} for chroma planes.
1864 Time of the current frame, expressed in seconds.
1867 Value of pixel component at current location for first video frame (top layer).
1870 Value of pixel component at current location for second video frame (bottom layer).
1874 Some examples follow.
1879 Apply transition from bottom layer to top layer in first 10 seconds:
1881 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
1885 Apply 1x1 checkerboard effect:
1887 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
1893 Apply boxblur algorithm to the input video.
1895 The filter accepts parameters as a list of @var{key}=@var{value}
1896 pairs, separated by ":". If the key of the first options is omitted,
1897 the arguments are interpreted according to the syntax
1898 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
1900 A description of the accepted options follows.
1903 @item luma_radius, lr
1904 @item chroma_radius, cr
1905 @item alpha_radius, ar
1906 Set an expression for the box radius in pixels used for blurring the
1907 corresponding input plane.
1909 The radius value must be a non-negative number, and must not be
1910 greater than the value of the expression @code{min(w,h)/2} for the
1911 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
1914 Default value for @option{luma_radius} is "2". If not specified,
1915 @option{chroma_radius} and @option{alpha_radius} default to the
1916 corresponding value set for @option{luma_radius}.
1918 The expressions can contain the following constants:
1921 the input width and height in pixels
1924 the input chroma image width and height in pixels
1927 horizontal and vertical chroma subsample values. For example for the
1928 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1931 @item luma_power, lp
1932 @item chroma_power, cp
1933 @item alpha_power, ap
1934 Specify how many times the boxblur filter is applied to the
1935 corresponding plane.
1937 Default value for @option{luma_power} is 2. If not specified,
1938 @option{chroma_power} and @option{alpha_power} default to the
1939 corresponding value set for @option{luma_power}.
1941 A value of 0 will disable the effect.
1944 Some examples follow.
1948 Apply a boxblur filter with luma, chroma, and alpha radius
1955 Set luma radius to 2, alpha and chroma radius to 0:
1957 boxblur=2:1:cr=0:ar=0
1961 Set luma and chroma radius to a fraction of the video dimension:
1963 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1967 @section colormatrix
1969 The colormatrix filter allows conversion between any of the following color
1970 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1971 and FCC (@var{fcc}).
1973 The syntax of the parameters is @var{source}:@var{destination}:
1976 colormatrix=bt601:smpte240m
1981 Copy the input source unchanged to the output. Mainly useful for
1986 Crop the input video.
1988 This filter accepts a list of @var{key}=@var{value} pairs as argument,
1989 separated by ':'. If the key of the first options is omitted, the
1990 arguments are interpreted according to the syntax
1991 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
1993 A description of the accepted options follows:
1996 Set the crop area width. It defaults to @code{iw}.
1997 This expression is evaluated only once during the filter
2001 Set the crop area width. It defaults to @code{ih}.
2002 This expression is evaluated only once during the filter
2006 Set the expression for the x top-left coordinate of the cropped area.
2007 It defaults to @code{(in_w-out_w)/2}.
2008 This expression is evaluated per-frame.
2011 Set the expression for the y top-left coordinate of the cropped area.
2012 It defaults to @code{(in_h-out_h)/2}.
2013 This expression is evaluated per-frame.
2016 If set to 1 will force the output display aspect ratio
2017 to be the same of the input, by changing the output sample aspect
2018 ratio. It defaults to 0.
2021 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2022 expressions containing the following constants:
2026 the computed values for @var{x} and @var{y}. They are evaluated for
2030 the input width and height
2033 same as @var{in_w} and @var{in_h}
2036 the output (cropped) width and height
2039 same as @var{out_w} and @var{out_h}
2042 same as @var{iw} / @var{ih}
2045 input sample aspect ratio
2048 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2051 horizontal and vertical chroma subsample values. For example for the
2052 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2055 the number of input frame, starting from 0
2058 the position in the file of the input frame, NAN if unknown
2061 timestamp expressed in seconds, NAN if the input timestamp is unknown
2065 The expression for @var{out_w} may depend on the value of @var{out_h},
2066 and the expression for @var{out_h} may depend on @var{out_w}, but they
2067 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2068 evaluated after @var{out_w} and @var{out_h}.
2070 The @var{x} and @var{y} parameters specify the expressions for the
2071 position of the top-left corner of the output (non-cropped) area. They
2072 are evaluated for each frame. If the evaluated value is not valid, it
2073 is approximated to the nearest valid value.
2075 The expression for @var{x} may depend on @var{y}, and the expression
2076 for @var{y} may depend on @var{x}.
2078 @subsection Examples
2081 Crop area with size 100x100 at position (12,34).
2086 Using named options, the example above becomes:
2088 crop=w=100:h=100:x=12:y=34
2092 Crop the central input area with size 100x100:
2098 Crop the central input area with size 2/3 of the input video:
2100 crop=2/3*in_w:2/3*in_h
2104 Crop the input video central square:
2110 Delimit the rectangle with the top-left corner placed at position
2111 100:100 and the right-bottom corner corresponding to the right-bottom
2112 corner of the input image:
2114 crop=in_w-100:in_h-100:100:100
2118 Crop 10 pixels from the left and right borders, and 20 pixels from
2119 the top and bottom borders
2121 crop=in_w-2*10:in_h-2*20
2125 Keep only the bottom right quarter of the input image:
2127 crop=in_w/2:in_h/2:in_w/2:in_h/2
2131 Crop height for getting Greek harmony:
2133 crop=in_w:1/PHI*in_w
2137 Appply trembling effect:
2139 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)
2143 Apply erratic camera effect depending on timestamp:
2145 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)"
2149 Set x depending on the value of y:
2151 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2157 Auto-detect crop size.
2159 Calculate necessary cropping parameters and prints the recommended
2160 parameters through the logging system. The detected dimensions
2161 correspond to the non-black area of the input video.
2163 It accepts the syntax:
2165 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
2171 Threshold, which can be optionally specified from nothing (0) to
2172 everything (255), defaults to 24.
2175 Value which the width/height should be divisible by, defaults to
2176 16. The offset is automatically adjusted to center the video. Use 2 to
2177 get only even dimensions (needed for 4:2:2 video). 16 is best when
2178 encoding to most video codecs.
2181 Counter that determines after how many frames cropdetect will reset
2182 the previously detected largest video area and start over to detect
2183 the current optimal crop area. Defaults to 0.
2185 This can be useful when channel logos distort the video area. 0
2186 indicates never reset and return the largest area encountered during
2192 Drop frames that do not differ greatly from the previous frame in
2193 order to reduce framerate.
2195 The main use of this filter is for very-low-bitrate encoding
2196 (e.g. streaming over dialup modem), but it could in theory be used for
2197 fixing movies that were inverse-telecined incorrectly.
2199 The filter accepts parameters as a list of @var{key}=@var{value}
2200 pairs, separated by ":". If the key of the first options is omitted,
2201 the arguments are interpreted according to the syntax:
2202 @option{max}:@option{hi}:@option{lo}:@option{frac}.
2204 A description of the accepted options follows.
2208 Set the maximum number of consecutive frames which can be dropped (if
2209 positive), or the minimum interval between dropped frames (if
2210 negative). If the value is 0, the frame is dropped unregarding the
2211 number of previous sequentially dropped frames.
2218 Set the dropping threshold values.
2220 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2221 represent actual pixel value differences, so a threshold of 64
2222 corresponds to 1 unit of difference for each pixel, or the same spread
2223 out differently over the block.
2225 A frame is a candidate for dropping if no 8x8 blocks differ by more
2226 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2227 meaning the whole image) differ by more than a threshold of @option{lo}.
2229 Default value for @option{hi} is 64*12, default value for @option{lo} is
2230 64*5, and default value for @option{frac} is 0.33.
2235 Suppress a TV station logo by a simple interpolation of the surrounding
2236 pixels. Just set a rectangle covering the logo and watch it disappear
2237 (and sometimes something even uglier appear - your mileage may vary).
2239 The filter accepts parameters as a string of the form
2240 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
2241 @var{key}=@var{value} pairs, separated by ":".
2243 The description of the accepted parameters follows.
2248 Specify the top left corner coordinates of the logo. They must be
2252 Specify the width and height of the logo to clear. They must be
2256 Specify the thickness of the fuzzy edge of the rectangle (added to
2257 @var{w} and @var{h}). The default value is 4.
2260 When set to 1, a green rectangle is drawn on the screen to simplify
2261 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2262 @var{band} is set to 4. The default value is 0.
2266 Some examples follow.
2271 Set a rectangle covering the area with top left corner coordinates 0,0
2272 and size 100x77, setting a band of size 10:
2274 delogo=0:0:100:77:10
2278 As the previous example, but use named options:
2280 delogo=x=0:y=0:w=100:h=77:band=10
2287 Attempt to fix small changes in horizontal and/or vertical shift. This
2288 filter helps remove camera shake from hand-holding a camera, bumping a
2289 tripod, moving on a vehicle, etc.
2291 The filter accepts parameters as a string of the form
2292 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
2294 A description of the accepted parameters follows.
2299 Specify a rectangular area where to limit the search for motion
2301 If desired the search for motion vectors can be limited to a
2302 rectangular area of the frame defined by its top left corner, width
2303 and height. These parameters have the same meaning as the drawbox
2304 filter which can be used to visualise the position of the bounding
2307 This is useful when simultaneous movement of subjects within the frame
2308 might be confused for camera motion by the motion vector search.
2310 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2311 then the full frame is used. This allows later options to be set
2312 without specifying the bounding box for the motion vector search.
2314 Default - search the whole frame.
2317 Specify the maximum extent of movement in x and y directions in the
2318 range 0-64 pixels. Default 16.
2321 Specify how to generate pixels to fill blanks at the edge of the
2322 frame. An integer from 0 to 3 as follows:
2325 Fill zeroes at blank locations
2327 Original image at blank locations
2329 Extruded edge value at blank locations
2331 Mirrored edge at blank locations
2334 The default setting is mirror edge at blank locations.
2337 Specify the blocksize to use for motion search. Range 4-128 pixels,
2341 Specify the contrast threshold for blocks. Only blocks with more than
2342 the specified contrast (difference between darkest and lightest
2343 pixels) will be considered. Range 1-255, default 125.
2346 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
2347 search. Default - exhaustive search.
2350 If set then a detailed log of the motion search is written to the
2357 Draw a colored box on the input image.
2359 The filter accepts parameters as a list of @var{key}=@var{value}
2360 pairs, separated by ":". If the key of the first options is omitted,
2361 the arguments are interpreted according to the syntax
2362 @option{x}:@option{y}:@option{width}:@option{height}:@option{color}:@option{thickness}.
2364 A description of the accepted options follows.
2368 Specify the top left corner coordinates of the box. Default to 0.
2372 Specify the width and height of the box, if 0 they are interpreted as
2373 the input width and height. Default to 0.
2376 Specify the color of the box to write, it can be the name of a color
2377 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2378 value @code{invert} is used, the box edge color is the same as the
2379 video with inverted luma.
2382 Set the thickness of the box edge. Default value is @code{4}.
2385 Some examples follow:
2388 Draw a black box around the edge of the input image:
2394 Draw a box with color red and an opacity of 50%:
2396 drawbox=10:20:200:60:red@@0.5
2399 The previous example can be specified as:
2401 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2405 Fill the box with pink color:
2407 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2414 Draw text string or text from specified file on top of video using the
2415 libfreetype library.
2417 To enable compilation of this filter you need to configure FFmpeg with
2418 @code{--enable-libfreetype}.
2422 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2425 The description of the accepted parameters follows.
2430 Used to draw a box around text using background color.
2431 Value should be either 1 (enable) or 0 (disable).
2432 The default value of @var{box} is 0.
2435 The color to be used for drawing box around text.
2436 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2437 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2438 The default value of @var{boxcolor} is "white".
2441 Set an expression which specifies if the text should be drawn. If the
2442 expression evaluates to 0, the text is not drawn. This is useful for
2443 specifying that the text should be drawn only when specific conditions
2446 Default value is "1".
2448 See below for the list of accepted constants and functions.
2451 Select how the @var{text} is expanded. Can be either @code{none},
2452 @code{strftime} (deprecated) or
2453 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2457 If true, check and fix text coords to avoid clipping.
2460 The color to be used for drawing fonts.
2461 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2462 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2463 The default value of @var{fontcolor} is "black".
2466 The font file to be used for drawing text. Path must be included.
2467 This parameter is mandatory.
2470 The font size to be used for drawing text.
2471 The default value of @var{fontsize} is 16.
2474 Flags to be used for loading the fonts.
2476 The flags map the corresponding flags supported by libfreetype, and are
2477 a combination of the following values:
2484 @item vertical_layout
2485 @item force_autohint
2488 @item ignore_global_advance_width
2490 @item ignore_transform
2497 Default value is "render".
2499 For more information consult the documentation for the FT_LOAD_*
2503 The color to be used for drawing a shadow behind the drawn text. It
2504 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2505 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2506 The default value of @var{shadowcolor} is "black".
2508 @item shadowx, shadowy
2509 The x and y offsets for the text shadow position with respect to the
2510 position of the text. They can be either positive or negative
2511 values. Default value for both is "0".
2514 The size in number of spaces to use for rendering the tab.
2518 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2519 format. It can be used with or without text parameter. @var{timecode_rate}
2520 option must be specified.
2522 @item timecode_rate, rate, r
2523 Set the timecode frame rate (timecode only).
2526 The text string to be drawn. The text must be a sequence of UTF-8
2528 This parameter is mandatory if no file is specified with the parameter
2532 A text file containing text to be drawn. The text must be a sequence
2533 of UTF-8 encoded characters.
2535 This parameter is mandatory if no text string is specified with the
2536 parameter @var{text}.
2538 If both @var{text} and @var{textfile} are specified, an error is thrown.
2541 If set to 1, the @var{textfile} will be reloaded before each frame.
2542 Be sure to update it atomically, or it may be read partially, or even fail.
2545 The expressions which specify the offsets where text will be drawn
2546 within the video frame. They are relative to the top/left border of the
2549 The default value of @var{x} and @var{y} is "0".
2551 See below for the list of accepted constants and functions.
2554 The parameters for @var{x} and @var{y} are expressions containing the
2555 following constants and functions:
2559 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2562 horizontal and vertical chroma subsample values. For example for the
2563 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2566 the height of each text line
2574 @item max_glyph_a, ascent
2575 the maximum distance from the baseline to the highest/upper grid
2576 coordinate used to place a glyph outline point, for all the rendered
2578 It is a positive value, due to the grid's orientation with the Y axis
2581 @item max_glyph_d, descent
2582 the maximum distance from the baseline to the lowest grid coordinate
2583 used to place a glyph outline point, for all the rendered glyphs.
2584 This is a negative value, due to the grid's orientation, with the Y axis
2588 maximum glyph height, that is the maximum height for all the glyphs
2589 contained in the rendered text, it is equivalent to @var{ascent} -
2593 maximum glyph width, that is the maximum width for all the glyphs
2594 contained in the rendered text
2597 the number of input frame, starting from 0
2599 @item rand(min, max)
2600 return a random number included between @var{min} and @var{max}
2603 input sample aspect ratio
2606 timestamp expressed in seconds, NAN if the input timestamp is unknown
2609 the height of the rendered text
2612 the width of the rendered text
2615 the x and y offset coordinates where the text is drawn.
2617 These parameters allow the @var{x} and @var{y} expressions to refer
2618 each other, so you can for example specify @code{y=x/dar}.
2621 If libavfilter was built with @code{--enable-fontconfig}, then
2622 @option{fontfile} can be a fontconfig pattern or omitted.
2624 @anchor{drawtext_expansion}
2625 @subsection Text expansion
2627 If @option{expansion} is set to @code{strftime},
2628 the filter recognizes strftime() sequences in the provided text and
2629 expands them accordingly. Check the documentation of strftime(). This
2630 feature is deprecated.
2632 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2634 If @option{expansion} is set to @code{normal} (which is the default),
2635 the following expansion mechanism is used.
2637 The backslash character '\', followed by any character, always expands to
2638 the second character.
2640 Sequence of the form @code{%@{...@}} are expanded. The text between the
2641 braces is a function name, possibly followed by arguments separated by ':'.
2642 If the arguments contain special characters or delimiters (':' or '@}'),
2643 they should be escaped.
2645 Note that they probably must also be escaped as the value for the
2646 @option{text} option in the filter argument string and as the filter
2647 argument in the filter graph description, and possibly also for the shell,
2648 that makes up to four levels of escaping; using a text file avoids these
2651 The following functions are available:
2656 The expression evaluation result.
2658 It must take one argument specifying the expression to be evaluated,
2659 which accepts the same constants and functions as the @var{x} and
2660 @var{y} values. Note that not all constants should be used, for
2661 example the text size is not known when evaluating the expression, so
2662 the constants @var{text_w} and @var{text_h} will have an undefined
2666 The time at which the filter is running, expressed in UTC.
2667 It can accept an argument: a strftime() format string.
2670 The time at which the filter is running, expressed in the local time zone.
2671 It can accept an argument: a strftime() format string.
2674 The frame number, starting from 0.
2677 The timestamp of the current frame, in seconds, with microsecond accuracy.
2681 @subsection Examples
2683 Some examples follow.
2688 Draw "Test Text" with font FreeSerif, using the default values for the
2689 optional parameters.
2692 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2696 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2697 and y=50 (counting from the top-left corner of the screen), text is
2698 yellow with a red box around it. Both the text and the box have an
2702 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2703 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2706 Note that the double quotes are not necessary if spaces are not used
2707 within the parameter list.
2710 Show the text at the center of the video frame:
2712 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2716 Show a text line sliding from right to left in the last row of the video
2717 frame. The file @file{LONG_LINE} is assumed to contain a single line
2720 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2724 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2726 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2730 Draw a single green letter "g", at the center of the input video.
2731 The glyph baseline is placed at half screen height.
2733 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2737 Show text for 1 second every 3 seconds:
2739 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2743 Use fontconfig to set the font. Note that the colons need to be escaped.
2745 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2749 Print the date of a real-time encoding (see strftime(3)):
2751 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2756 For more information about libfreetype, check:
2757 @url{http://www.freetype.org/}.
2759 For more information about fontconfig, check:
2760 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2764 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2766 This filter accepts the following optional named parameters:
2770 Set low and high threshold values used by the Canny thresholding
2773 The high threshold selects the "strong" edge pixels, which are then
2774 connected through 8-connectivity with the "weak" edge pixels selected
2775 by the low threshold.
2777 @var{low} and @var{high} threshold values must be choosen in the range
2778 [0,1], and @var{low} should be lesser or equal to @var{high}.
2780 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2786 edgedetect=low=0.1:high=0.4
2791 Apply fade-in/out effect to input video.
2793 The filter accepts parameters as a list of @var{key}=@var{value}
2794 pairs, separated by ":". If the key of the first options is omitted,
2795 the arguments are interpreted according to the syntax
2796 @var{type}:@var{start_frame}:@var{nb_frames}.
2798 A description of the accepted parameters follows.
2802 Specify if the effect type, can be either @code{in} for fade-in, or
2803 @code{out} for a fade-out effect. Default is @code{in}.
2805 @item start_frame, s
2806 Specify the number of the start frame for starting to apply the fade
2807 effect. Default is 0.
2810 Specify the number of frames for which the fade effect has to last. At
2811 the end of the fade-in effect the output video will have the same
2812 intensity as the input video, at the end of the fade-out transition
2813 the output video will be completely black. Default is 25.
2816 If set to 1, fade only alpha channel, if one exists on the input.
2820 @subsection Examples
2823 Fade in first 30 frames of video:
2828 The command above is equivalent to:
2834 Fade out last 45 frames of a 200-frame video:
2840 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
2842 fade=in:0:25, fade=out:975:25
2846 Make first 5 frames black, then fade in from frame 5-24:
2852 Fade in alpha over first 25 frames of video:
2854 fade=in:0:25:alpha=1
2860 Extract a single field from an interlaced image using stride
2861 arithmetic to avoid wasting CPU time. The output frames are marked as
2864 This filter accepts the following named options:
2867 Specify whether to extract the top (if the value is @code{0} or
2868 @code{top}) or the bottom field (if the value is @code{1} or
2872 If the option key is not specified, the first value sets the @var{type}
2873 option. For example:
2885 Transform the field order of the input video.
2887 It accepts one parameter which specifies the required field order that
2888 the input interlaced video will be transformed to. The parameter can
2889 assume one of the following values:
2893 output bottom field first
2895 output top field first
2898 Default value is "tff".
2900 Transformation is achieved by shifting the picture content up or down
2901 by one line, and filling the remaining line with appropriate picture content.
2902 This method is consistent with most broadcast field order converters.
2904 If the input video is not flagged as being interlaced, or it is already
2905 flagged as being of the required output field order then this filter does
2906 not alter the incoming video.
2908 This filter is very useful when converting to or from PAL DV material,
2909 which is bottom field first.
2913 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2918 Buffer input images and send them when they are requested.
2920 This filter is mainly useful when auto-inserted by the libavfilter
2923 The filter does not take parameters.
2927 Convert the input video to one of the specified pixel formats.
2928 Libavfilter will try to pick one that is supported for the input to
2931 The filter accepts a list of pixel format names, separated by ":",
2932 for example "yuv420p:monow:rgb24".
2934 Some examples follow:
2936 # convert the input video to the format "yuv420p"
2939 # convert the input video to any of the formats in the list
2940 format=yuv420p:yuv444p:yuv410p
2945 Convert the video to specified constant framerate by duplicating or dropping
2946 frames as necessary.
2948 This filter accepts the following named parameters:
2952 Desired output framerate. The default is @code{25}.
2957 Possible values are:
2960 zero round towards 0
2964 round towards -infinity
2966 round towards +infinity
2970 The default is @code{near}.
2974 Alternatively, the options can be specified as a flat string:
2975 @var{fps}[:@var{round}].
2977 See also the @ref{setpts} filter.
2981 Select one frame every N.
2983 This filter accepts in input a string representing a positive
2984 integer. Default argument is @code{1}.
2989 Apply a frei0r effect to the input video.
2991 To enable compilation of this filter you need to install the frei0r
2992 header and configure FFmpeg with @code{--enable-frei0r}.
2994 The filter supports the syntax:
2996 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2999 @var{filter_name} is the name of the frei0r effect to load. If the
3000 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
3001 is searched in each one of the directories specified by the colon (or
3002 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
3003 otherwise in the standard frei0r paths, which are in this order:
3004 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3005 @file{/usr/lib/frei0r-1/}.
3007 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
3008 for the frei0r effect.
3010 A frei0r effect parameter can be a boolean (whose values are specified
3011 with "y" and "n"), a double, a color (specified by the syntax
3012 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3013 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3014 description), a position (specified by the syntax @var{X}/@var{Y},
3015 @var{X} and @var{Y} being float numbers) and a string.
3017 The number and kind of parameters depend on the loaded effect. If an
3018 effect parameter is not specified the default value is set.
3020 Some examples follow:
3024 Apply the distort0r effect, set the first two double parameters:
3026 frei0r=distort0r:0.5:0.01
3030 Apply the colordistance effect, take a color as first parameter:
3032 frei0r=colordistance:0.2/0.3/0.4
3033 frei0r=colordistance:violet
3034 frei0r=colordistance:0x112233
3038 Apply the perspective effect, specify the top left and top right image
3041 frei0r=perspective:0.2/0.2:0.8/0.2
3045 For more information see:
3046 @url{http://frei0r.dyne.org}
3050 The filter takes one, two or three equations as parameter, separated by ':'.
3051 The first equation is mandatory and applies to the luma plane. The two
3052 following are respectively for chroma blue and chroma red planes.
3054 The filter syntax allows named parameters:
3058 the luminance expression
3060 the chrominance blue expression
3062 the chrominance red expression
3065 If one of the chrominance expression is not defined, it falls back on the other
3066 one. If none of them are specified, they will evaluate the luminance
3069 The expressions can use the following variables and functions:
3073 The sequential number of the filtered frame, starting from @code{0}.
3076 The coordinates of the current sample.
3079 The width and height of the image.
3082 Width and height scale depending on the currently filtered plane. It is the
3083 ratio between the corresponding luma plane number of pixels and the current
3084 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3085 @code{0.5,0.5} for chroma planes.
3088 Time of the current frame, expressed in seconds.
3091 Return the value of the pixel at location (@var{x},@var{y}) of the current
3095 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3099 Return the value of the pixel at location (@var{x},@var{y}) of the
3100 blue-difference chroma plane.
3103 Return the value of the pixel at location (@var{x},@var{y}) of the
3104 red-difference chroma plane.
3107 For functions, if @var{x} and @var{y} are outside the area, the value will be
3108 automatically clipped to the closer edge.
3110 Some examples follow:
3114 Flip the image horizontally:
3120 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3121 wavelength of 100 pixels:
3123 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3127 Generate a fancy enigmatic moving light:
3129 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
3135 Fix the banding artifacts that are sometimes introduced into nearly flat
3136 regions by truncation to 8bit color depth.
3137 Interpolate the gradients that should go where the bands are, and
3140 This filter is designed for playback only. Do not use it prior to
3141 lossy compression, because compression tends to lose the dither and
3142 bring back the bands.
3144 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
3145 separated by ":". A description of the accepted options follows.
3150 The maximum amount by which the filter will change
3151 any one pixel. Also the threshold for detecting nearly flat
3152 regions. Acceptable values range from @code{0.51} to @code{64}, default value
3156 The neighborhood to fit the gradient to. A larger
3157 radius makes for smoother gradients, but also prevents the filter from
3158 modifying the pixels near detailed regions. Acceptable values are
3159 @code{8-32}, default value is @code{16}.
3163 Alternatively, the options can be specified as a flat string:
3164 @var{strength}[:@var{radius}]
3166 @subsection Examples
3170 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3176 Specify radius, omitting the strength (which will fall-back to the default
3186 Flip the input video horizontally.
3188 For example to horizontally flip the input video with @command{ffmpeg}:
3190 ffmpeg -i in.avi -vf "hflip" out.avi
3194 This filter applies a global color histogram equalization on a
3197 It can be used to correct video that has a compressed range of pixel
3198 intensities. The filter redistributes the pixel intensities to
3199 equalize their distribution across the intensity range. It may be
3200 viewed as an "automatically adjusting contrast filter". This filter is
3201 useful only for correcting degraded or poorly captured source
3204 The filter accepts parameters as a list of @var{key}=@var{value}
3205 pairs, separated by ":". If the key of the first options is omitted,
3206 the arguments are interpreted according to syntax
3207 @var{strength}:@var{intensity}:@var{antibanding}.
3209 This filter accepts the following named options:
3213 Determine the amount of equalization to be applied. As the strength
3214 is reduced, the distribution of pixel intensities more-and-more
3215 approaches that of the input frame. The value must be a float number
3216 in the range [0,1] and defaults to 0.200.
3219 Set the maximum intensity that can generated and scale the output
3220 values appropriately. The strength should be set as desired and then
3221 the intensity can be limited if needed to avoid washing-out. The value
3222 must be a float number in the range [0,1] and defaults to 0.210.
3225 Set the antibanding level. If enabled the filter will randomly vary
3226 the luminance of output pixels by a small amount to avoid banding of
3227 the histogram. Possible values are @code{none}, @code{weak} or
3228 @code{strong}. It defaults to @code{none}.
3233 Compute and draw a color distribution histogram for the input video.
3235 The computed histogram is a representation of distribution of color components
3238 The filter accepts the following named parameters:
3244 It accepts the following values:
3247 standard histogram that display color components distribution in an image.
3248 Displays color graph for each color component. Shows distribution
3249 of the Y, U, V, A or G, B, R components, depending on input format,
3250 in current frame. Bellow each graph is color component scale meter.
3253 chroma values in vectorscope, if brighter more such chroma values are
3254 distributed in an image.
3255 Displays chroma values (U/V color placement) in two dimensional graph
3256 (which is called a vectorscope). It can be used to read of the hue and
3257 saturation of the current frame. At a same time it is a histogram.
3258 The whiter a pixel in the vectorscope, the more pixels of the input frame
3259 correspond to that pixel (that is the more pixels have this chroma value).
3260 The V component is displayed on the horizontal (X) axis, with the leftmost
3261 side being V = 0 and the rightmost side being V = 255.
3262 The U component is displayed on the vertical (Y) axis, with the top
3263 representing U = 0 and the bottom representing U = 255.
3265 The position of a white pixel in the graph corresponds to the chroma value
3266 of a pixel of the input clip. So the graph can be used to read of the
3267 hue (color flavor) and the saturation (the dominance of the hue in the color).
3268 As the hue of a color changes, it moves around the square. At the center of
3269 the square, the saturation is zero, which means that the corresponding pixel
3270 has no color. If you increase the amount of a specific color, while leaving
3271 the other colors unchanged, the saturation increases, and you move towards
3272 the edge of the square.
3275 chroma values in vectorscope, similar as @code{color} but actual chroma values
3279 per row/column color component graph. In row mode graph in the left side represents
3280 color component value 0 and right side represents value = 255. In column mode top
3281 side represents color component value = 0 and bottom side represents value = 255.
3283 Default value is @code{levels}.
3286 Set height of level in @code{levels}. Default value is @code{200}.
3287 Allowed range is [50, 2048].
3290 Set height of color scale in @code{levels}. Default value is @code{12}.
3291 Allowed range is [0, 40].
3294 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3295 of same luminance values across input rows/columns are distributed.
3296 Default value is @code{10}. Allowed range is [1, 255].
3299 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3300 Default is @code{row}.
3303 Set display mode for @code{waveform} and @code{levels}.
3304 It accepts the following values:
3307 Display separate graph for the color components side by side in
3308 @code{row} waveform mode or one below other in @code{column} waveform mode
3309 for @code{waveform} histogram mode. For @code{levels} histogram mode
3310 per color component graphs are placed one bellow other.
3312 This display mode in @code{waveform} histogram mode makes it easy to spot
3313 color casts in the highlights and shadows of an image, by comparing the
3314 contours of the top and the bottom of each waveform.
3315 Since whites, grays, and blacks are characterized by
3316 exactly equal amounts of red, green, and blue, neutral areas of the
3317 picture should display three waveforms of roughly equal width/height.
3318 If not, the correction is easy to make by making adjustments to level the
3322 Presents information that's identical to that in the @code{parade}, except
3323 that the graphs representing color components are superimposed directly
3326 This display mode in @code{waveform} histogram mode can make it easier to spot
3327 the relative differences or similarities in overlapping areas of the color
3328 components that are supposed to be identical, such as neutral whites, grays,
3331 Default is @code{parade}.
3334 @subsection Examples
3339 Calculate and draw histogram:
3341 ffplay -i input -vf histogram
3348 High precision/quality 3d denoise filter. This filter aims to reduce
3349 image noise producing smooth images and making still images really
3350 still. It should enhance compressibility.
3352 It accepts the following optional parameters:
3353 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3357 a non-negative float number which specifies spatial luma strength,
3360 @item chroma_spatial
3361 a non-negative float number which specifies spatial chroma strength,
3362 defaults to 3.0*@var{luma_spatial}/4.0
3365 a float number which specifies luma temporal strength, defaults to
3366 6.0*@var{luma_spatial}/4.0
3369 a float number which specifies chroma temporal strength, defaults to
3370 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3375 Modify the hue and/or the saturation of the input.
3377 This filter accepts the following optional named options:
3381 Specify the hue angle as a number of degrees. It accepts a float
3382 number or an expression, and defaults to 0.0.
3385 Specify the hue angle as a number of degrees. It accepts a float
3386 number or an expression, and defaults to 0.0.
3389 Specify the saturation in the [-10,10] range. It accepts a float number and
3393 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3394 following constants:
3398 frame count of the input frame starting from 0
3401 presentation timestamp of the input frame expressed in time base units
3404 frame rate of the input video, NAN if the input frame rate is unknown
3407 timestamp expressed in seconds, NAN if the input timestamp is unknown
3410 time base of the input video
3413 The options can also be set using the syntax: @var{hue}:@var{saturation}
3415 In this case @var{hue} is expressed in degrees.
3417 Some examples follow:
3420 Set the hue to 90 degrees and the saturation to 1.0:
3426 Same command but expressing the hue in radians:
3432 Same command without named options, hue must be expressed in degrees:
3438 Note that "h:s" syntax does not support expressions for the values of
3439 h and s, so the following example will issue an error:
3445 Rotate hue and make the saturation swing between 0
3446 and 2 over a period of 1 second:
3448 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3452 Apply a 3 seconds saturation fade-in effect starting at 0:
3457 The general fade-in expression can be written as:
3459 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3463 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3465 hue="s=max(0\, min(1\, (8-t)/3))"
3468 The general fade-out expression can be written as:
3470 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3475 @subsection Commands
3477 This filter supports the following command:
3480 Modify the hue and/or the saturation of the input video.
3481 The command accepts the same named options and syntax than when calling the
3482 filter from the command-line.
3484 If a parameter is omitted, it is kept at its current value.
3489 Detect video interlacing type.
3491 This filter tries to detect if the input is interlaced or progressive,
3492 top or bottom field first.
3496 Deinterleave or interleave fields.
3498 This filter allows to process interlaced images fields without
3499 deinterlacing them. Deinterleaving splits the input frame into 2
3500 fields (so called half pictures). Odd lines are moved to the top
3501 half of the output image, even lines to the bottom half.
3502 You can process (filter) them independently and then re-interleave them.
3504 It accepts a list of options in the form of @var{key}=@var{value} pairs
3505 separated by ":". A description of the accepted options follows.
3509 @item chroma_mode, s
3511 Available values for @var{luma_mode}, @var{chroma_mode} and
3512 @var{alpha_mode} are:
3518 @item deinterleave, d
3519 Deinterleave fields, placing one above the other.
3522 Interleave fields. Reverse the effect of deinterleaving.
3524 Default value is @code{none}.
3527 @item chroma_swap, cs
3528 @item alpha_swap, as
3529 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3534 Deinterlace input video by applying Donald Graft's adaptive kernel
3535 deinterling. Work on interlaced parts of a video to produce
3538 This filter accepts parameters as a list of @var{key}=@var{value}
3539 pairs, separated by ":". If the key of the first options is omitted,
3540 the arguments are interpreted according to the following syntax:
3541 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3543 The description of the accepted parameters follows.
3547 Set the threshold which affects the filter's tolerance when
3548 determining if a pixel line must be processed. It must be an integer
3549 in the range [0,255] and defaults to 10. A value of 0 will result in
3550 applying the process on every pixels.
3553 Paint pixels exceeding the threshold value to white if set to 1.
3557 Set the fields order. Swap fields if set to 1, leave fields alone if
3561 Enable additional sharpening if set to 1. Default is 0.
3564 Enable twoway sharpening if set to 1. Default is 0.
3567 @subsection Examples
3571 Apply default values:
3573 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3577 Enable additional sharpening:
3583 Paint processed pixels in white:
3589 @section lut, lutrgb, lutyuv
3591 Compute a look-up table for binding each pixel component input value
3592 to an output value, and apply it to input video.
3594 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3595 to an RGB input video.
3597 These filters accept in input a ":"-separated list of options, which
3598 specify the expressions used for computing the lookup table for the
3599 corresponding pixel component values.
3601 The @var{lut} filter requires either YUV or RGB pixel formats in
3602 input, and accepts the options:
3605 set first pixel component expression
3607 set second pixel component expression
3609 set third pixel component expression
3611 set fourth pixel component expression, corresponds to the alpha component
3614 The exact component associated to each option depends on the format in
3617 The @var{lutrgb} filter requires RGB pixel formats in input, and
3618 accepts the options:
3621 set red component expression
3623 set green component expression
3625 set blue component expression
3627 alpha component expression
3630 The @var{lutyuv} filter requires YUV pixel formats in input, and
3631 accepts the options:
3634 set Y/luminance component expression
3636 set U/Cb component expression
3638 set V/Cr component expression
3640 set alpha component expression
3643 The expressions can contain the following constants and functions:
3647 the input width and height
3650 input value for the pixel component
3653 the input value clipped in the @var{minval}-@var{maxval} range
3656 maximum value for the pixel component
3659 minimum value for the pixel component
3662 the negated value for the pixel component value clipped in the
3663 @var{minval}-@var{maxval} range , it corresponds to the expression
3664 "maxval-clipval+minval"
3667 the computed value in @var{val} clipped in the
3668 @var{minval}-@var{maxval} range
3670 @item gammaval(gamma)
3671 the computed gamma correction value of the pixel component value
3672 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3674 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3678 All expressions default to "val".
3680 @subsection Examples
3686 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3687 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3690 The above is the same as:
3692 lutrgb="r=negval:g=negval:b=negval"
3693 lutyuv="y=negval:u=negval:v=negval"
3703 Remove chroma components, turns the video into a graytone image:
3705 lutyuv="u=128:v=128"
3709 Apply a luma burning effect:
3715 Remove green and blue components:
3721 Set a constant alpha channel value on input:
3723 format=rgba,lutrgb=a="maxval-minval/2"
3727 Correct luminance gamma by a 0.5 factor:
3729 lutyuv=y=gammaval(0.5)
3735 Apply an MPlayer filter to the input video.
3737 This filter provides a wrapper around most of the filters of
3740 This wrapper is considered experimental. Some of the wrapped filters
3741 may not work properly and we may drop support for them, as they will
3742 be implemented natively into FFmpeg. Thus you should avoid
3743 depending on them when writing portable scripts.
3745 The filters accepts the parameters:
3746 @var{filter_name}[:=]@var{filter_params}
3748 @var{filter_name} is the name of a supported MPlayer filter,
3749 @var{filter_params} is a string containing the parameters accepted by
3752 The list of the currently supported filters follows:
3780 The parameter syntax and behavior for the listed filters are the same
3781 of the corresponding MPlayer filters. For detailed instructions check
3782 the "VIDEO FILTERS" section in the MPlayer manual.
3784 Some examples follow:
3787 Adjust gamma, brightness, contrast:
3793 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3799 This filter accepts an integer in input, if non-zero it negates the
3800 alpha component (if available). The default value in input is 0.
3804 Force libavfilter not to use any of the specified pixel formats for the
3805 input to the next filter.
3807 The filter accepts a list of pixel format names, separated by ":",
3808 for example "yuv420p:monow:rgb24".
3810 Some examples follow:
3812 # force libavfilter to use a format different from "yuv420p" for the
3813 # input to the vflip filter
3814 noformat=yuv420p,vflip
3816 # convert the input video to any of the formats not contained in the list
3817 noformat=yuv420p:yuv444p:yuv410p
3822 Add noise on video input frame.
3824 This filter accepts a list of options in the form of @var{key}=@var{value}
3825 pairs separated by ":". A description of the accepted options follows.
3833 Set noise seed for specific pixel component or all pixel components in case
3834 of @var{all_seed}. Default value is @code{123457}.
3836 @item all_strength, as
3837 @item c0_strength, c0s
3838 @item c1_strength, c1s
3839 @item c2_strength, c2s
3840 @item c3_strength, c3s
3841 Set noise strength for specific pixel component or all pixel components in case
3842 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
3849 Set pixel component flags or set flags for all components if @var{all_flags}.
3850 Available values for component flags are:
3853 averaged temporal noise (smoother)
3855 mix random noise with a (semi)regular pattern
3857 higher quality (slightly better looking, slightly slower)
3859 temporal noise (noise pattern changes between frames)
3861 uniform noise (gaussian otherwise)
3865 Some examples follow:
3867 Add temporal and uniform noise to input video:
3868 noise=alls=20:allf=t+u
3873 Pass the video source unchanged to the output.
3877 Apply video transform using libopencv.
3879 To enable this filter install libopencv library and headers and
3880 configure FFmpeg with @code{--enable-libopencv}.
3882 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3884 @var{filter_name} is the name of the libopencv filter to apply.
3886 @var{filter_params} specifies the parameters to pass to the libopencv
3887 filter. If not specified the default values are assumed.
3889 Refer to the official libopencv documentation for more precise
3891 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3893 Follows the list of supported libopencv filters.
3898 Dilate an image by using a specific structuring element.
3899 This filter corresponds to the libopencv function @code{cvDilate}.
3901 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3903 @var{struct_el} represents a structuring element, and has the syntax:
3904 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3906 @var{cols} and @var{rows} represent the number of columns and rows of
3907 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3908 point, and @var{shape} the shape for the structuring element, and
3909 can be one of the values "rect", "cross", "ellipse", "custom".
3911 If the value for @var{shape} is "custom", it must be followed by a
3912 string of the form "=@var{filename}". The file with name
3913 @var{filename} is assumed to represent a binary image, with each
3914 printable character corresponding to a bright pixel. When a custom
3915 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3916 or columns and rows of the read file are assumed instead.
3918 The default value for @var{struct_el} is "3x3+0x0/rect".
3920 @var{nb_iterations} specifies the number of times the transform is
3921 applied to the image, and defaults to 1.
3923 Follow some example:
3925 # use the default values
3928 # dilate using a structuring element with a 5x5 cross, iterate two times
3929 ocv=dilate=5x5+2x2/cross:2
3931 # read the shape from the file diamond.shape, iterate two times
3932 # the file diamond.shape may contain a pattern of characters like this:
3938 # the specified cols and rows are ignored (but not the anchor point coordinates)
3939 ocv=0x0+2x2/custom=diamond.shape:2
3944 Erode an image by using a specific structuring element.
3945 This filter corresponds to the libopencv function @code{cvErode}.
3947 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3948 with the same syntax and semantics as the @ref{dilate} filter.
3952 Smooth the input video.
3954 The filter takes the following parameters:
3955 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3957 @var{type} is the type of smooth filter to apply, and can be one of
3958 the following values: "blur", "blur_no_scale", "median", "gaussian",
3959 "bilateral". The default value is "gaussian".
3961 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3962 parameters whose meanings depend on smooth type. @var{param1} and
3963 @var{param2} accept integer positive values or 0, @var{param3} and
3964 @var{param4} accept float values.
3966 The default value for @var{param1} is 3, the default value for the
3967 other parameters is 0.
3969 These parameters correspond to the parameters assigned to the
3970 libopencv function @code{cvSmooth}.
3975 Overlay one video on top of another.
3977 It takes two inputs and one output, the first input is the "main"
3978 video on which the second input is overlayed.
3980 This filter accepts a list of @var{key}=@var{value} pairs as argument,
3981 separated by ":". If the key of the first options is omitted, the
3982 arguments are interpreted according to the syntax @var{x}:@var{y}.
3984 A description of the accepted options follows.
3988 Set the expression for the x and y coordinates of the overlayed video
3989 on the main video. Default value is 0.
3991 The @var{x} and @var{y} expressions can contain the following
3994 @item main_w, main_h
3995 main input width and height
3998 same as @var{main_w} and @var{main_h}
4000 @item overlay_w, overlay_h
4001 overlay input width and height
4004 same as @var{overlay_w} and @var{overlay_h}
4008 Set the format for the output video.
4010 It accepts the following values:
4022 Default value is @samp{yuv420}.
4024 @item rgb @emph{(deprecated)}
4025 If set to 1, force the filter to accept inputs in the RGB
4026 color space. Default value is 0. This option is deprecated, use
4027 @option{format} instead.
4030 If set to 1, force the output to terminate when the shortest input
4031 terminates. Default value is 0.
4034 Be aware that frames are taken from each input video in timestamp
4035 order, hence, if their initial timestamps differ, it is a a good idea
4036 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4037 have them begin in the same zero timestamp, as it does the example for
4038 the @var{movie} filter.
4040 You can chain together more overlays but you should test the
4041 efficiency of such approach.
4043 @subsection Examples
4047 Draw the overlay at 10 pixels from the bottom right corner of the main
4050 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4053 Using named options the example above becomes:
4055 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4059 Insert a transparent PNG logo in the bottom left corner of the input,
4060 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4062 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4066 Insert 2 different transparent PNG logos (second logo on bottom
4067 right corner) using the @command{ffmpeg} tool:
4069 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
4073 Add a transparent color layer on top of the main video, WxH specifies
4074 the size of the main input to the overlay filter:
4076 color=red@@.3:WxH [over]; [in][over] overlay [out]
4080 Play an original video and a filtered version (here with the deshake
4081 filter) side by side using the @command{ffplay} tool:
4083 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4086 The above command is the same as:
4088 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4092 Compose output by putting two input videos side to side:
4094 ffmpeg -i left.avi -i right.avi -filter_complex "
4095 nullsrc=size=200x100 [background];
4096 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4097 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4098 [background][left] overlay=shortest=1 [background+left];
4099 [background+left][right] overlay=shortest=1:x=100 [left+right]
4104 Chain several overlays in cascade:
4106 nullsrc=s=200x200 [bg];
4107 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4108 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4109 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4110 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4111 [in3] null, [mid2] overlay=100:100 [out0]
4118 Add paddings to the input image, and place the original input at the
4119 given coordinates @var{x}, @var{y}.
4121 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
4124 If the key of the first options is omitted, the arguments are
4125 interpreted according to the syntax
4126 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
4128 A description of the accepted options follows.
4133 Specify an expression for the size of the output image with the
4134 paddings added. If the value for @var{width} or @var{height} is 0, the
4135 corresponding input size is used for the output.
4137 The @var{width} expression can reference the value set by the
4138 @var{height} expression, and vice versa.
4140 The default value of @var{width} and @var{height} is 0.
4144 Specify an expression for the offsets where to place the input image
4145 in the padded area with respect to the top/left border of the output
4148 The @var{x} expression can reference the value set by the @var{y}
4149 expression, and vice versa.
4151 The default value of @var{x} and @var{y} is 0.
4154 Specify the color of the padded area, it can be the name of a color
4155 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4157 The default value of @var{color} is "black".
4160 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4161 options are expressions containing the following constants:
4165 the input video width and height
4168 same as @var{in_w} and @var{in_h}
4171 the output width and height, that is the size of the padded area as
4172 specified by the @var{width} and @var{height} expressions
4175 same as @var{out_w} and @var{out_h}
4178 x and y offsets as specified by the @var{x} and @var{y}
4179 expressions, or NAN if not yet specified
4182 same as @var{iw} / @var{ih}
4185 input sample aspect ratio
4188 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4191 horizontal and vertical chroma subsample values. For example for the
4192 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4195 @subsection Examples
4199 Add paddings with color "violet" to the input video. Output video
4200 size is 640x480, the top-left corner of the input video is placed at
4203 pad=640:480:0:40:violet
4206 The example above is equivalent to the following command:
4208 pad=width=640:height=480:x=0:y=40:color=violet
4212 Pad the input to get an output with dimensions increased by 3/2,
4213 and put the input video at the center of the padded area:
4215 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4219 Pad the input to get a squared output with size equal to the maximum
4220 value between the input width and height, and put the input video at
4221 the center of the padded area:
4223 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4227 Pad the input to get a final w/h ratio of 16:9:
4229 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4233 In case of anamorphic video, in order to set the output display aspect
4234 correctly, it is necessary to use @var{sar} in the expression,
4235 according to the relation:
4237 (ih * X / ih) * sar = output_dar
4238 X = output_dar / sar
4241 Thus the previous example needs to be modified to:
4243 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4247 Double output size and put the input video in the bottom-right
4248 corner of the output padded area:
4250 pad="2*iw:2*ih:ow-iw:oh-ih"
4254 @section pixdesctest
4256 Pixel format descriptor test filter, mainly useful for internal
4257 testing. The output video should be equal to the input video.
4261 format=monow, pixdesctest
4264 can be used to test the monowhite pixel format descriptor definition.
4268 Enable the specified chain of postprocessing subfilters using libpostproc. This
4269 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4270 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4271 Each subfilter and some options have a short and a long name that can be used
4272 interchangeably, i.e. dr/dering are the same.
4274 All subfilters share common options to determine their scope:
4278 Honor the quality commands for this subfilter.
4281 Do chrominance filtering, too (default).
4284 Do luminance filtering only (no chrominance).
4287 Do chrominance filtering only (no luminance).
4290 These options can be appended after the subfilter name, separated by a ':'.
4292 Available subfilters are:
4295 @item hb/hdeblock[:difference[:flatness]]
4296 Horizontal deblocking filter
4299 Difference factor where higher values mean more deblocking (default: @code{32}).
4301 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4304 @item vb/vdeblock[:difference[:flatness]]
4305 Vertical deblocking filter
4308 Difference factor where higher values mean more deblocking (default: @code{32}).
4310 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4313 @item ha/hadeblock[:difference[:flatness]]
4314 Accurate horizontal deblocking filter
4317 Difference factor where higher values mean more deblocking (default: @code{32}).
4319 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4322 @item va/vadeblock[:difference[:flatness]]
4323 Accurate vertical deblocking filter
4326 Difference factor where higher values mean more deblocking (default: @code{32}).
4328 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4332 The horizontal and vertical deblocking filters share the difference and
4333 flatness values so you cannot set different horizontal and vertical
4338 Experimental horizontal deblocking filter
4341 Experimental vertical deblocking filter
4346 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
4349 larger -> stronger filtering
4351 larger -> stronger filtering
4353 larger -> stronger filtering
4356 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4359 Stretch luminance to @code{0-255}.
4362 @item lb/linblenddeint
4363 Linear blend deinterlacing filter that deinterlaces the given block by
4364 filtering all lines with a @code{(1 2 1)} filter.
4366 @item li/linipoldeint
4367 Linear interpolating deinterlacing filter that deinterlaces the given block by
4368 linearly interpolating every second line.
4370 @item ci/cubicipoldeint
4371 Cubic interpolating deinterlacing filter deinterlaces the given block by
4372 cubically interpolating every second line.
4374 @item md/mediandeint
4375 Median deinterlacing filter that deinterlaces the given block by applying a
4376 median filter to every second line.
4378 @item fd/ffmpegdeint
4379 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4380 second line with a @code{(-1 4 2 4 -1)} filter.
4383 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4384 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4386 @item fq/forceQuant[:quantizer]
4387 Overrides the quantizer table from the input with the constant quantizer you
4395 Default pp filter combination (@code{hb:a,vb:a,dr:a})
4398 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
4401 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
4404 @subsection Examples
4408 Apply horizontal and vertical deblocking, deringing and automatic
4409 brightness/contrast:
4415 Apply default filters without brightness/contrast correction:
4421 Apply default filters and temporal denoiser:
4423 pp=default/tmpnoise:1:2:3
4427 Apply deblocking on luminance only, and switch vertical deblocking on or off
4428 automatically depending on available CPU time:
4436 Suppress a TV station logo, using an image file to determine which
4437 pixels comprise the logo. It works by filling in the pixels that
4438 comprise the logo with neighboring pixels.
4440 This filter requires one argument which specifies the filter bitmap
4441 file, which can be any image format supported by libavformat. The
4442 width and height of the image file must match those of the video
4443 stream being processed.
4445 Pixels in the provided bitmap image with a value of zero are not
4446 considered part of the logo, non-zero pixels are considered part of
4447 the logo. If you use white (255) for the logo and black (0) for the
4448 rest, you will be safe. For making the filter bitmap, it is
4449 recommended to take a screen capture of a black frame with the logo
4450 visible, and then using a threshold filter followed by the erode
4451 filter once or twice.
4453 If needed, little splotches can be fixed manually. Remember that if
4454 logo pixels are not covered, the filter quality will be much
4455 reduced. Marking too many pixels as part of the logo does not hurt as
4456 much, but it will increase the amount of blurring needed to cover over
4457 the image and will destroy more information than necessary, and extra
4458 pixels will slow things down on a large logo.
4462 Scale (resize) the input video, using the libswscale library.
4464 The scale filter forces the output display aspect ratio to be the same
4465 of the input, by changing the output sample aspect ratio.
4467 This filter accepts a list of named options in the form of
4468 @var{key}=@var{value} pairs separated by ":". If the key for the first
4469 two options is not specified, the assumed keys for the first two
4470 values are @code{w} and @code{h}. If the first option has no key and
4471 can be interpreted like a video size specification, it will be used
4472 to set the video size.
4474 A description of the accepted options follows.
4478 Set the video width expression, default value is @code{iw}. See below
4479 for the list of accepted constants.
4482 Set the video heiht expression, default value is @code{ih}.
4483 See below for the list of accepted constants.
4486 Set the interlacing. It accepts the following values:
4490 force interlaced aware scaling
4493 do not apply interlaced scaling
4496 select interlaced aware scaling depending on whether the source frames
4497 are flagged as interlaced or not
4500 Default value is @code{0}.
4503 Set libswscale scaling flags. If not explictly specified the filter
4504 applies a bilinear scaling algorithm.
4507 Set the video size, the value must be a valid abbreviation or in the
4508 form @var{width}x@var{height}.
4511 The values of the @var{w} and @var{h} options are expressions
4512 containing the following constants:
4516 the input width and height
4519 same as @var{in_w} and @var{in_h}
4522 the output (cropped) width and height
4525 same as @var{out_w} and @var{out_h}
4528 same as @var{iw} / @var{ih}
4531 input sample aspect ratio
4534 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4537 horizontal and vertical chroma subsample values. For example for the
4538 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4541 If the input image format is different from the format requested by
4542 the next filter, the scale filter will convert the input to the
4545 If the value for @var{width} or @var{height} is 0, the respective input
4546 size is used for the output.
4548 If the value for @var{width} or @var{height} is -1, the scale filter will
4549 use, for the respective output size, a value that maintains the aspect
4550 ratio of the input image.
4552 @subsection Examples
4556 Scale the input video to a size of 200x100:
4561 This is equivalent to:
4572 Specify a size abbreviation for the output size:
4577 which can also be written as:
4583 Scale the input to 2x:
4589 The above is the same as:
4595 Scale the input to 2x with forced interlaced scaling:
4597 scale=2*iw:2*ih:interl=1
4601 Scale the input to half size:
4607 Increase the width, and set the height to the same size:
4613 Seek for Greek harmony:
4620 Increase the height, and set the width to 3/2 of the height:
4626 Increase the size, but make the size a multiple of the chroma:
4628 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4632 Increase the width to a maximum of 500 pixels, keep the same input
4635 scale='min(500\, iw*3/2):-1'
4639 @section setdar, setsar
4641 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4644 This is done by changing the specified Sample (aka Pixel) Aspect
4645 Ratio, according to the following equation:
4647 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4650 Keep in mind that the @code{setdar} filter does not modify the pixel
4651 dimensions of the video frame. Also the display aspect ratio set by
4652 this filter may be changed by later filters in the filterchain,
4653 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4656 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4657 the filter output video.
4659 Note that as a consequence of the application of this filter, the
4660 output display aspect ratio will change according to the equation
4663 Keep in mind that the sample aspect ratio set by the @code{setsar}
4664 filter may be changed by later filters in the filterchain, e.g. if
4665 another "setsar" or a "setdar" filter is applied.
4667 The @code{setdar} and @code{setsar} filters accept a string in the
4668 form @var{num}:@var{den} expressing an aspect ratio, or the following
4669 named options, expressed as a sequence of @var{key}=@var{value} pairs,
4674 Set the maximum integer value to use for expressing numerator and
4675 denominator when reducing the expressed aspect ratio to a rational.
4676 Default value is @code{100}.
4679 Set the aspect ratio used by the filter.
4681 The parameter can be a floating point number string, an expression, or
4682 a string of the form @var{num}:@var{den}, where @var{num} and
4683 @var{den} are the numerator and denominator of the aspect ratio. If
4684 the parameter is not specified, it is assumed the value "0".
4685 In case the form "@var{num}:@var{den}" the @code{:} character should
4689 If the keys are omitted in the named options list, the specifed values
4690 are assumed to be @var{ratio} and @var{max} in that order.
4692 For example to change the display aspect ratio to 16:9, specify:
4697 The example above is equivalent to:
4702 To change the sample aspect ratio to 10:11, specify:
4707 To set a display aspect ratio of 16:9, and specify a maximum integer value of
4708 1000 in the aspect ratio reduction, use the command:
4710 setdar=ratio='16:9':max=1000
4715 Force field for the output video frame.
4717 The @code{setfield} filter marks the interlace type field for the
4718 output frames. It does not change the input frame, but only sets the
4719 corresponding property, which affects how the frame is treated by
4720 following filters (e.g. @code{fieldorder} or @code{yadif}).
4722 This filter accepts a single option @option{mode}, which can be
4723 specified either by setting @code{mode=VALUE} or setting the value
4724 alone. Available values are:
4728 Keep the same field property.
4731 Mark the frame as bottom-field-first.
4734 Mark the frame as top-field-first.
4737 Mark the frame as progressive.
4742 Show a line containing various information for each input video frame.
4743 The input video is not modified.
4745 The shown line contains a sequence of key/value pairs of the form
4746 @var{key}:@var{value}.
4748 A description of each shown parameter follows:
4752 sequential number of the input frame, starting from 0
4755 Presentation TimeStamp of the input frame, expressed as a number of
4756 time base units. The time base unit depends on the filter input pad.
4759 Presentation TimeStamp of the input frame, expressed as a number of
4763 position of the frame in the input stream, -1 if this information in
4764 unavailable and/or meaningless (for example in case of synthetic video)
4770 sample aspect ratio of the input frame, expressed in the form
4774 size of the input frame, expressed in the form
4775 @var{width}x@var{height}
4778 interlaced mode ("P" for "progressive", "T" for top field first, "B"
4779 for bottom field first)
4782 1 if the frame is a key frame, 0 otherwise
4785 picture type of the input frame ("I" for an I-frame, "P" for a
4786 P-frame, "B" for a B-frame, "?" for unknown type).
4787 Check also the documentation of the @code{AVPictureType} enum and of
4788 the @code{av_get_picture_type_char} function defined in
4789 @file{libavutil/avutil.h}.
4792 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
4794 @item plane_checksum
4795 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
4796 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
4801 Blur the input video without impacting the outlines.
4803 The filter accepts the following parameters:
4804 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
4806 Parameters prefixed by @var{luma} indicate that they work on the
4807 luminance of the pixels whereas parameters prefixed by @var{chroma}
4808 refer to the chrominance of the pixels.
4810 If the chroma parameters are not set, the luma parameters are used for
4811 either the luminance and the chrominance of the pixels.
4813 @var{luma_radius} or @var{chroma_radius} must be a float number in the
4814 range [0.1,5.0] that specifies the variance of the gaussian filter
4815 used to blur the image (slower if larger).
4817 @var{luma_strength} or @var{chroma_strength} must be a float number in
4818 the range [-1.0,1.0] that configures the blurring. A value included in
4819 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
4820 will sharpen the image.
4822 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
4823 the range [-30,30] that is used as a coefficient to determine whether
4824 a pixel should be blurred or not. A value of 0 will filter all the
4825 image, a value included in [0,30] will filter flat areas and a value
4826 included in [-30,0] will filter edges.
4831 Draw subtitles on top of input video using the libass library.
4833 To enable compilation of this filter you need to configure FFmpeg with
4834 @code{--enable-libass}. This filter also requires a build with libavcodec and
4835 libavformat to convert the passed subtitles file to ASS (Advanced Substation
4836 Alpha) subtitles format.
4838 This filter accepts the following named options, expressed as a
4839 sequence of @var{key}=@var{value} pairs, separated by ":".
4843 Set the filename of the subtitle file to read. It must be specified.
4846 Specify the size of the original video, the video for which the ASS file
4847 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
4848 necessary to correctly scale the fonts if the aspect ratio has been changed.
4851 Set subtitles input character encoding. @code{subtitles} filter only. Only
4852 useful if not UTF-8.
4855 If the first key is not specified, it is assumed that the first value
4856 specifies the @option{filename}.
4858 For example, to render the file @file{sub.srt} on top of the input
4859 video, use the command:
4864 which is equivalent to:
4866 subtitles=filename=sub.srt
4871 Split input video into several identical outputs.
4873 The filter accepts a single parameter which specifies the number of outputs. If
4874 unspecified, it defaults to 2.
4878 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
4880 will create 5 copies of the input video.
4884 [in] split [splitout1][splitout2];
4885 [splitout1] crop=100:100:0:0 [cropout];
4886 [splitout2] pad=200:200:100:100 [padout];
4889 will create two separate outputs from the same input, one cropped and
4894 Scale the input by 2x and smooth using the Super2xSaI (Scale and
4895 Interpolate) pixel art scaling algorithm.
4897 Useful for enlarging pixel art images without reducing sharpness.
4903 Select the most representative frame in a given sequence of consecutive frames.
4905 It accepts as argument the frames batch size to analyze (default @var{N}=100);
4906 in a set of @var{N} frames, the filter will pick one of them, and then handle
4907 the next batch of @var{N} frames until the end.
4909 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
4910 value will result in a higher memory usage, so a high value is not recommended.
4912 The following example extract one picture each 50 frames:
4917 Complete example of a thumbnail creation with @command{ffmpeg}:
4919 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
4924 Tile several successive frames together.
4926 It accepts a list of options in the form of @var{key}=@var{value} pairs
4927 separated by ":". A description of the accepted options follows.
4932 Set the grid size (i.e. the number of lines and columns) in the form
4936 Set the outer border margin in pixels.
4939 Set the inner border thickness (i.e. the number of pixels between frames). For
4940 more advanced padding options (such as having different values for the edges),
4941 refer to the pad video filter.
4944 Set the maximum number of frames to render in the given area. It must be less
4945 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
4946 the area will be used.
4950 Alternatively, the options can be specified as a flat string:
4952 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
4954 For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
4957 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
4959 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
4960 duplicating each output frame to accomodate the originally detected frame
4963 Another example to display @code{5} pictures in an area of @code{3x2} frames,
4964 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
4965 mixed flat and named options:
4967 tile=3x2:nb_frames=5:padding=7:margin=2
4972 Perform various types of temporal field interlacing.
4974 Frames are counted starting from 1, so the first input frame is
4977 This filter accepts options in the form of @var{key}=@var{value} pairs
4979 Alternatively, the @var{mode} option can be specified as a value alone,
4980 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
4983 A description of the accepted options follows.
4988 Specify the mode of the interlacing. This option can also be specified
4989 as a value alone. See below for a list of values for this option.
4991 Available values are:
4995 Move odd frames into the upper field, even into the lower field,
4996 generating a double height frame at half framerate.
4999 Only output even frames, odd frames are dropped, generating a frame with
5000 unchanged height at half framerate.
5003 Only output odd frames, even frames are dropped, generating a frame with
5004 unchanged height at half framerate.
5007 Expand each frame to full height, but pad alternate lines with black,
5008 generating a frame with double height at the same input framerate.
5010 @item interleave_top, 4
5011 Interleave the upper field from odd frames with the lower field from
5012 even frames, generating a frame with unchanged height at half framerate.
5014 @item interleave_bottom, 5
5015 Interleave the lower field from odd frames with the upper field from
5016 even frames, generating a frame with unchanged height at half framerate.
5018 @item interlacex2, 6
5019 Double frame rate with unchanged height. Frames are inserted each
5020 containing the second temporal field from the previous input frame and
5021 the first temporal field from the next input frame. This mode relies on
5022 the top_field_first flag. Useful for interlaced video displays with no
5023 field synchronisation.
5026 Numeric values are deprecated but are accepted for backward
5027 compatibility reasons.
5029 Default mode is @code{merge}.
5032 Specify flags influencing the filter process.
5034 Available value for @var{flags} is:
5037 @item low_pass_filter, vlfp
5038 Enable vertical low-pass filtering in the filter.
5039 Vertical low-pass filtering is required when creating an interlaced
5040 destination from a progressive source which contains high-frequency
5041 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5044 Vertical low-pass filtering can only be enabled for @option{mode}
5045 @var{interleave_top} and @var{interleave_bottom}.
5052 Transpose rows with columns in the input video and optionally flip it.
5054 The filter accepts parameters as a list of @var{key}=@var{value}
5055 pairs, separated by ':'. If the key of the first options is omitted,
5056 the arguments are interpreted according to the syntax
5057 @var{dir}:@var{passthrough}.
5061 Specify the transposition direction. Can assume the following values:
5065 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5073 Rotate by 90 degrees clockwise, that is:
5081 Rotate by 90 degrees counterclockwise, that is:
5089 Rotate by 90 degrees clockwise and vertically flip, that is:
5097 For values between 4-7, the transposition is only done if the input
5098 video geometry is portrait and not landscape. These values are
5099 deprecated, the @code{passthrough} option should be used instead.
5102 Do not apply the transposition if the input geometry matches the one
5103 specified by the specified value. It accepts the following values:
5106 Always apply transposition.
5108 Preserve portrait geometry (when @var{height} >= @var{width}).
5110 Preserve landscape geometry (when @var{width} >= @var{height}).
5113 Default value is @code{none}.
5116 For example to rotate by 90 degrees clockwise and preserve portrait
5119 transpose=dir=1:passthrough=portrait
5122 The command above can also be specified as:
5124 transpose=1:portrait
5129 Sharpen or blur the input video.
5131 This filter accepts parameters as a list of @var{key}=@var{value} pairs,
5134 If the key of the first options is omitted, the arguments are
5135 interpreted according to the syntax:
5136 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
5138 A description of the accepted options follows.
5141 @item luma_msize_x, lx
5142 @item chroma_msize_x, cx
5143 Set the luma/chroma matrix horizontal size. It must be an odd integer
5144 between 3 and 63, default value is 5.
5146 @item luma_msize_y, ly
5147 @item chroma_msize_y, cy
5148 Set the luma/chroma matrix vertical size. It must be an odd integer
5149 between 3 and 63, default value is 5.
5151 @item luma_amount, la
5152 @item chroma_amount, ca
5153 Set the luma/chroma effect strength. It can be a float number,
5154 reasonable values lay between -1.5 and 1.5.
5156 Negative values will blur the input video, while positive values will
5157 sharpen it, a value of zero will disable the effect.
5159 Default value is 1.0 for @option{luma_amount}, 0.0 for
5160 @option{chroma_amount}.
5163 Some examples follow:
5166 Apply strong luma sharpen effect:
5172 Apply strong blur of both luma and chroma parameters:
5174 unsharp=7:7:-2:7:7:-2
5180 Flip the input video vertically.
5183 ffmpeg -i in.avi -vf "vflip" out.avi
5188 Deinterlace the input video ("yadif" means "yet another deinterlacing
5191 The filter accepts parameters as a list of @var{key}=@var{value}
5192 pairs, separated by ":". If the key of the first options is omitted,
5193 the arguments are interpreted according to syntax
5194 @var{mode}:@var{parity}:@var{deint}.
5196 The description of the accepted parameters follows.
5200 Specify the interlacing mode to adopt. Accept one of the following
5205 output 1 frame for each frame
5207 output 1 frame for each field
5208 @item 2, send_frame_nospatial
5209 like @code{send_frame} but skip spatial interlacing check
5210 @item 3, send_field_nospatial
5211 like @code{send_field} but skip spatial interlacing check
5214 Default value is @code{send_frame}.
5217 Specify the picture field parity assumed for the input interlaced
5218 video. Accept one of the following values:
5222 assume top field first
5224 assume bottom field first
5226 enable automatic detection
5229 Default value is @code{auto}.
5230 If interlacing is unknown or decoder does not export this information,
5231 top field first will be assumed.
5234 Specify which frames to deinterlace. Accept one of the following
5239 deinterlace all frames
5241 only deinterlace frames marked as interlaced
5244 Default value is @code{all}.
5247 @c man end VIDEO FILTERS
5249 @chapter Video Sources
5250 @c man begin VIDEO SOURCES
5252 Below is a description of the currently available video sources.
5256 Buffer video frames, and make them available to the filter chain.
5258 This source is mainly intended for a programmatic use, in particular
5259 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5261 It accepts a list of options in the form of @var{key}=@var{value} pairs
5262 separated by ":". A description of the accepted options follows.
5267 Specify the size (width and height) of the buffered video frames.
5270 A string representing the pixel format of the buffered video frames.
5271 It may be a number corresponding to a pixel format, or a pixel format
5275 Specify the timebase assumed by the timestamps of the buffered frames.
5278 Specify the frame rate expected for the video stream.
5281 Specify the sample aspect ratio assumed by the video frames.
5284 Specify the optional parameters to be used for the scale filter which
5285 is automatically inserted when an input change is detected in the
5286 input size or format.
5291 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5294 will instruct the source to accept video frames with size 320x240 and
5295 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5296 square pixels (1:1 sample aspect ratio).
5297 Since the pixel format with name "yuv410p" corresponds to the number 6
5298 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5299 this example corresponds to:
5301 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5304 Alternatively, the options can be specified as a flat string, but this
5305 syntax is deprecated:
5307 @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}]
5311 Create a pattern generated by an elementary cellular automaton.
5313 The initial state of the cellular automaton can be defined through the
5314 @option{filename}, and @option{pattern} options. If such options are
5315 not specified an initial state is created randomly.
5317 At each new frame a new row in the video is filled with the result of
5318 the cellular automaton next generation. The behavior when the whole
5319 frame is filled is defined by the @option{scroll} option.
5321 This source accepts a list of options in the form of
5322 @var{key}=@var{value} pairs separated by ":". A description of the
5323 accepted options follows.
5327 Read the initial cellular automaton state, i.e. the starting row, from
5329 In the file, each non-whitespace character is considered an alive
5330 cell, a newline will terminate the row, and further characters in the
5331 file will be ignored.
5334 Read the initial cellular automaton state, i.e. the starting row, from
5335 the specified string.
5337 Each non-whitespace character in the string is considered an alive
5338 cell, a newline will terminate the row, and further characters in the
5339 string will be ignored.
5342 Set the video rate, that is the number of frames generated per second.
5345 @item random_fill_ratio, ratio
5346 Set the random fill ratio for the initial cellular automaton row. It
5347 is a floating point number value ranging from 0 to 1, defaults to
5350 This option is ignored when a file or a pattern is specified.
5352 @item random_seed, seed
5353 Set the seed for filling randomly the initial row, must be an integer
5354 included between 0 and UINT32_MAX. If not specified, or if explicitly
5355 set to -1, the filter will try to use a good random seed on a best
5359 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5360 Default value is 110.
5363 Set the size of the output video.
5365 If @option{filename} or @option{pattern} is specified, the size is set
5366 by default to the width of the specified initial state row, and the
5367 height is set to @var{width} * PHI.
5369 If @option{size} is set, it must contain the width of the specified
5370 pattern string, and the specified pattern will be centered in the
5373 If a filename or a pattern string is not specified, the size value
5374 defaults to "320x518" (used for a randomly generated initial state).
5377 If set to 1, scroll the output upward when all the rows in the output
5378 have been already filled. If set to 0, the new generated row will be
5379 written over the top row just after the bottom row is filled.
5382 @item start_full, full
5383 If set to 1, completely fill the output with generated rows before
5384 outputting the first frame.
5385 This is the default behavior, for disabling set the value to 0.
5388 If set to 1, stitch the left and right row edges together.
5389 This is the default behavior, for disabling set the value to 0.
5392 @subsection Examples
5396 Read the initial state from @file{pattern}, and specify an output of
5399 cellauto=f=pattern:s=200x400
5403 Generate a random initial row with a width of 200 cells, with a fill
5406 cellauto=ratio=2/3:s=200x200
5410 Create a pattern generated by rule 18 starting by a single alive cell
5411 centered on an initial row with width 100:
5413 cellauto=p=@@:s=100x400:full=0:rule=18
5417 Specify a more elaborated initial pattern:
5419 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5426 Generate a Mandelbrot set fractal, and progressively zoom towards the
5427 point specified with @var{start_x} and @var{start_y}.
5429 This source accepts a list of options in the form of
5430 @var{key}=@var{value} pairs separated by ":". A description of the
5431 accepted options follows.
5436 Set the terminal pts value. Default value is 400.
5439 Set the terminal scale value.
5440 Must be a floating point value. Default value is 0.3.
5443 Set the inner coloring mode, that is the algorithm used to draw the
5444 Mandelbrot fractal internal region.
5446 It shall assume one of the following values:
5451 Show time until convergence.
5453 Set color based on point closest to the origin of the iterations.
5458 Default value is @var{mincol}.
5461 Set the bailout value. Default value is 10.0.
5464 Set the maximum of iterations performed by the rendering
5465 algorithm. Default value is 7189.
5468 Set outer coloring mode.
5469 It shall assume one of following values:
5471 @item iteration_count
5472 Set iteration cound mode.
5473 @item normalized_iteration_count
5474 set normalized iteration count mode.
5476 Default value is @var{normalized_iteration_count}.
5479 Set frame rate, expressed as number of frames per second. Default
5483 Set frame size. Default value is "640x480".
5486 Set the initial scale value. Default value is 3.0.
5489 Set the initial x position. Must be a floating point value between
5490 -100 and 100. Default value is -0.743643887037158704752191506114774.
5493 Set the initial y position. Must be a floating point value between
5494 -100 and 100. Default value is -0.131825904205311970493132056385139.
5499 Generate various test patterns, as generated by the MPlayer test filter.
5501 The size of the generated video is fixed, and is 256x256.
5502 This source is useful in particular for testing encoding features.
5504 This source accepts an optional sequence of @var{key}=@var{value} pairs,
5505 separated by ":". The description of the accepted options follows.
5510 Specify the frame rate of the sourced video, as the number of frames
5511 generated per second. It has to be a string in the format
5512 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5513 number or a valid video frame rate abbreviation. The default value is
5517 Set the video duration of the sourced video. The accepted syntax is:
5522 See also the function @code{av_parse_time()}.
5524 If not specified, or the expressed duration is negative, the video is
5525 supposed to be generated forever.
5529 Set the number or the name of the test to perform. Supported tests are:
5544 Default value is "all", which will cycle through the list of all tests.
5547 For example the following:
5552 will generate a "dc_luma" test pattern.
5556 Provide a frei0r source.
5558 To enable compilation of this filter you need to install the frei0r
5559 header and configure FFmpeg with @code{--enable-frei0r}.
5561 The source supports the syntax:
5563 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
5566 @var{size} is the size of the video to generate, may be a string of the
5567 form @var{width}x@var{height} or a frame size abbreviation.
5568 @var{rate} is the rate of the video to generate, may be a string of
5569 the form @var{num}/@var{den} or a frame rate abbreviation.
5570 @var{src_name} is the name to the frei0r source to load. For more
5571 information regarding frei0r and how to set the parameters read the
5572 section @ref{frei0r} in the description of the video filters.
5574 For example, to generate a frei0r partik0l source with size 200x200
5575 and frame rate 10 which is overlayed on the overlay filter main input:
5577 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
5582 Generate a life pattern.
5584 This source is based on a generalization of John Conway's life game.
5586 The sourced input represents a life grid, each pixel represents a cell
5587 which can be in one of two possible states, alive or dead. Every cell
5588 interacts with its eight neighbours, which are the cells that are
5589 horizontally, vertically, or diagonally adjacent.
5591 At each interaction the grid evolves according to the adopted rule,
5592 which specifies the number of neighbor alive cells which will make a
5593 cell stay alive or born. The @option{rule} option allows to specify
5596 This source accepts a list of options in the form of
5597 @var{key}=@var{value} pairs separated by ":". A description of the
5598 accepted options follows.
5602 Set the file from which to read the initial grid state. In the file,
5603 each non-whitespace character is considered an alive cell, and newline
5604 is used to delimit the end of each row.
5606 If this option is not specified, the initial grid is generated
5610 Set the video rate, that is the number of frames generated per second.
5613 @item random_fill_ratio, ratio
5614 Set the random fill ratio for the initial random grid. It is a
5615 floating point number value ranging from 0 to 1, defaults to 1/PHI.
5616 It is ignored when a file is specified.
5618 @item random_seed, seed
5619 Set the seed for filling the initial random grid, must be an integer
5620 included between 0 and UINT32_MAX. If not specified, or if explicitly
5621 set to -1, the filter will try to use a good random seed on a best
5627 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
5628 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
5629 @var{NS} specifies the number of alive neighbor cells which make a
5630 live cell stay alive, and @var{NB} the number of alive neighbor cells
5631 which make a dead cell to become alive (i.e. to "born").
5632 "s" and "b" can be used in place of "S" and "B", respectively.
5634 Alternatively a rule can be specified by an 18-bits integer. The 9
5635 high order bits are used to encode the next cell state if it is alive
5636 for each number of neighbor alive cells, the low order bits specify
5637 the rule for "borning" new cells. Higher order bits encode for an
5638 higher number of neighbor cells.
5639 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
5640 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
5642 Default value is "S23/B3", which is the original Conway's game of life
5643 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
5644 cells, and will born a new cell if there are three alive cells around
5648 Set the size of the output video.
5650 If @option{filename} is specified, the size is set by default to the
5651 same size of the input file. If @option{size} is set, it must contain
5652 the size specified in the input file, and the initial grid defined in
5653 that file is centered in the larger resulting area.
5655 If a filename is not specified, the size value defaults to "320x240"
5656 (used for a randomly generated initial grid).
5659 If set to 1, stitch the left and right grid edges together, and the
5660 top and bottom edges also. Defaults to 1.
5663 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
5664 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
5665 value from 0 to 255.
5668 Set the color of living (or new born) cells.
5671 Set the color of dead cells. If @option{mold} is set, this is the first color
5672 used to represent a dead cell.
5675 Set mold color, for definitely dead and moldy cells.
5678 @subsection Examples
5682 Read a grid from @file{pattern}, and center it on a grid of size
5685 life=f=pattern:s=300x300
5689 Generate a random grid of size 200x200, with a fill ratio of 2/3:
5691 life=ratio=2/3:s=200x200
5695 Specify a custom rule for evolving a randomly generated grid:
5701 Full example with slow death effect (mold) using @command{ffplay}:
5703 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
5707 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
5709 The @code{color} source provides an uniformly colored input.
5711 The @code{nullsrc} source returns unprocessed video frames. It is
5712 mainly useful to be employed in analysis / debugging tools, or as the
5713 source for filters which ignore the input data.
5715 The @code{rgbtestsrc} source generates an RGB test pattern useful for
5716 detecting RGB vs BGR issues. You should see a red, green and blue
5717 stripe from top to bottom.
5719 The @code{smptebars} source generates a color bars pattern, based on
5720 the SMPTE Engineering Guideline EG 1-1990.
5722 The @code{testsrc} source generates a test video pattern, showing a
5723 color pattern, a scrolling gradient and a timestamp. This is mainly
5724 intended for testing purposes.
5726 These sources accept an optional sequence of @var{key}=@var{value} pairs,
5727 separated by ":". The description of the accepted options follows.
5732 Specify the color of the source, only used in the @code{color}
5733 source. It can be the name of a color (case insensitive match) or a
5734 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
5735 default value is "black".
5738 Specify the size of the sourced video, it may be a string of the form
5739 @var{width}x@var{height}, or the name of a size abbreviation. The
5740 default value is "320x240".
5743 Specify the frame rate of the sourced video, as the number of frames
5744 generated per second. It has to be a string in the format
5745 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5746 number or a valid video frame rate abbreviation. The default value is
5750 Set the sample aspect ratio of the sourced video.
5753 Set the video duration of the sourced video. The accepted syntax is:
5755 [-]HH[:MM[:SS[.m...]]]
5758 See also the function @code{av_parse_time()}.
5760 If not specified, or the expressed duration is negative, the video is
5761 supposed to be generated forever.
5764 Set the number of decimals to show in the timestamp, only used in the
5765 @code{testsrc} source.
5767 The displayed timestamp value will correspond to the original
5768 timestamp value multiplied by the power of 10 of the specified
5769 value. Default value is 0.
5772 For example the following:
5774 testsrc=duration=5.3:size=qcif:rate=10
5777 will generate a video with a duration of 5.3 seconds, with size
5778 176x144 and a frame rate of 10 frames per second.
5780 The following graph description will generate a red source
5781 with an opacity of 0.2, with size "qcif" and a frame rate of 10
5784 color=c=red@@0.2:s=qcif:r=10
5787 If the input content is to be ignored, @code{nullsrc} can be used. The
5788 following command generates noise in the luminance plane by employing
5789 the @code{geq} filter:
5791 nullsrc=s=256x256, geq=random(1)*255:128:128
5794 @c man end VIDEO SOURCES
5796 @chapter Video Sinks
5797 @c man begin VIDEO SINKS
5799 Below is a description of the currently available video sinks.
5803 Buffer video frames, and make them available to the end of the filter
5806 This sink is mainly intended for a programmatic use, in particular
5807 through the interface defined in @file{libavfilter/buffersink.h}.
5809 It does not require a string parameter in input, but you need to
5810 specify a pointer to a list of supported pixel formats terminated by
5811 -1 in the opaque parameter provided to @code{avfilter_init_filter}
5812 when initializing this sink.
5816 Null video sink, do absolutely nothing with the input video. It is
5817 mainly useful as a template and to be employed in analysis / debugging
5820 @c man end VIDEO SINKS
5822 @chapter Multimedia Filters
5823 @c man begin MULTIMEDIA FILTERS
5825 Below is a description of the currently available multimedia filters.
5827 @section aselect, select
5828 Select frames to pass in output.
5830 These filters accept a single option @option{expr} or @option{e}
5831 specifying the select expression, which can be specified either by
5832 specyfing @code{expr=VALUE} or specifying the expression
5835 The select expression is evaluated for each input frame. If the
5836 evaluation result is a non-zero value, the frame is selected and
5837 passed to the output, otherwise it is discarded.
5839 The expression can contain the following constants:
5843 the sequential number of the filtered frame, starting from 0
5846 the sequential number of the selected frame, starting from 0
5848 @item prev_selected_n
5849 the sequential number of the last selected frame, NAN if undefined
5852 timebase of the input timestamps
5855 the PTS (Presentation TimeStamp) of the filtered video frame,
5856 expressed in @var{TB} units, NAN if undefined
5859 the PTS (Presentation TimeStamp) of the filtered video frame,
5860 expressed in seconds, NAN if undefined
5863 the PTS of the previously filtered video frame, NAN if undefined
5865 @item prev_selected_pts
5866 the PTS of the last previously filtered video frame, NAN if undefined
5868 @item prev_selected_t
5869 the PTS of the last previously selected video frame, NAN if undefined
5872 the PTS of the first video frame in the video, NAN if undefined
5875 the time of the first video frame in the video, NAN if undefined
5877 @item pict_type @emph{(video only)}
5878 the type of the filtered frame, can assume one of the following
5890 @item interlace_type @emph{(video only)}
5891 the frame interlace type, can assume one of the following values:
5894 the frame is progressive (not interlaced)
5896 the frame is top-field-first
5898 the frame is bottom-field-first
5901 @item consumed_sample_n @emph{(audio only)}
5902 the number of selected samples before the current frame
5904 @item samples_n @emph{(audio only)}
5905 the number of samples in the current frame
5907 @item sample_rate @emph{(audio only)}
5908 the input sample rate
5911 1 if the filtered frame is a key-frame, 0 otherwise
5914 the position in the file of the filtered frame, -1 if the information
5915 is not available (e.g. for synthetic video)
5917 @item scene @emph{(video only)}
5918 value between 0 and 1 to indicate a new scene; a low value reflects a low
5919 probability for the current frame to introduce a new scene, while a higher
5920 value means the current frame is more likely to be one (see the example below)
5924 The default value of the select expression is "1".
5926 @subsection Examples
5930 Select all frames in input:
5935 The example above is the same as:
5947 Select only I-frames:
5949 select='eq(pict_type\,I)'
5953 Select one frame every 100:
5955 select='not(mod(n\,100))'
5959 Select only frames contained in the 10-20 time interval:
5961 select='gte(t\,10)*lte(t\,20)'
5965 Select only I frames contained in the 10-20 time interval:
5967 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
5971 Select frames with a minimum distance of 10 seconds:
5973 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
5977 Use aselect to select only audio frames with samples number > 100:
5979 aselect='gt(samples_n\,100)'
5983 Create a mosaic of the first scenes:
5985 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
5988 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
5992 @section asendcmd, sendcmd
5994 Send commands to filters in the filtergraph.
5996 These filters read commands to be sent to other filters in the
5999 @code{asendcmd} must be inserted between two audio filters,
6000 @code{sendcmd} must be inserted between two video filters, but apart
6001 from that they act the same way.
6003 The specification of commands can be provided in the filter arguments
6004 with the @var{commands} option, or in a file specified by the
6005 @var{filename} option.
6007 These filters accept the following options:
6010 Set the commands to be read and sent to the other filters.
6012 Set the filename of the commands to be read and sent to the other
6016 @subsection Commands syntax
6018 A commands description consists of a sequence of interval
6019 specifications, comprising a list of commands to be executed when a
6020 particular event related to that interval occurs. The occurring event
6021 is typically the current frame time entering or leaving a given time
6024 An interval is specified by the following syntax:
6026 @var{START}[-@var{END}] @var{COMMANDS};
6029 The time interval is specified by the @var{START} and @var{END} times.
6030 @var{END} is optional and defaults to the maximum time.
6032 The current frame time is considered within the specified interval if
6033 it is included in the interval [@var{START}, @var{END}), that is when
6034 the time is greater or equal to @var{START} and is lesser than
6037 @var{COMMANDS} consists of a sequence of one or more command
6038 specifications, separated by ",", relating to that interval. The
6039 syntax of a command specification is given by:
6041 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6044 @var{FLAGS} is optional and specifies the type of events relating to
6045 the time interval which enable sending the specified command, and must
6046 be a non-null sequence of identifier flags separated by "+" or "|" and
6047 enclosed between "[" and "]".
6049 The following flags are recognized:
6052 The command is sent when the current frame timestamp enters the
6053 specified interval. In other words, the command is sent when the
6054 previous frame timestamp was not in the given interval, and the
6058 The command is sent when the current frame timestamp leaves the
6059 specified interval. In other words, the command is sent when the
6060 previous frame timestamp was in the given interval, and the
6064 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6067 @var{TARGET} specifies the target of the command, usually the name of
6068 the filter class or a specific filter instance name.
6070 @var{COMMAND} specifies the name of the command for the target filter.
6072 @var{ARG} is optional and specifies the optional list of argument for
6073 the given @var{COMMAND}.
6075 Between one interval specification and another, whitespaces, or
6076 sequences of characters starting with @code{#} until the end of line,
6077 are ignored and can be used to annotate comments.
6079 A simplified BNF description of the commands specification syntax
6082 @var{COMMAND_FLAG} ::= "enter" | "leave"
6083 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6084 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6085 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6086 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6087 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6090 @subsection Examples
6094 Specify audio tempo change at second 4:
6096 asendcmd=c='4.0 atempo tempo 1.5',atempo
6100 Specify a list of drawtext and hue commands in a file.
6102 # show text in the interval 5-10
6103 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6104 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6106 # desaturate the image in the interval 15-20
6107 15.0-20.0 [enter] hue reinit s=0,
6108 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6109 [leave] hue reinit s=1,
6110 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6112 # apply an exponential saturation fade-out effect, starting from time 25
6113 25 [enter] hue s=exp(t-25)
6116 A filtergraph allowing to read and process the above command list
6117 stored in a file @file{test.cmd}, can be specified with:
6119 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6124 @section asetpts, setpts
6126 Change the PTS (presentation timestamp) of the input frames.
6128 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6130 Accept in input an expression evaluated through the eval API, which
6131 can contain the following constants:
6135 frame rate, only defined for constant frame-rate video
6138 the presentation timestamp in input
6141 the count of the input frame, starting from 0.
6143 @item NB_CONSUMED_SAMPLES
6144 the number of consumed samples, not including the current frame (only
6148 the number of samples in the current frame (only audio)
6154 the PTS of the first frame
6157 the time in seconds of the first frame
6160 tell if the current frame is interlaced
6163 the time in seconds of the current frame
6169 original position in the file of the frame, or undefined if undefined
6170 for the current frame
6176 previous input time in seconds
6182 previous output time in seconds
6185 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6189 wallclock (RTC) time at the start of the movie in microseconds
6192 @subsection Examples
6196 Start counting PTS from zero
6202 Apply fast motion effect:
6208 Apply slow motion effect:
6214 Set fixed rate of 25 frames per second:
6220 Set fixed rate 25 fps with some jitter:
6222 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6226 Apply an offset of 10 seconds to the input PTS:
6232 Generate timestamps from a "live source" and rebase onto the current timebase:
6234 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6240 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6241 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6242 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6243 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6245 The filter also has a video output (see the @var{video} option) with a real
6246 time graph to observe the loudness evolution. The graphic contains the logged
6247 message mentioned above, so it is not printed anymore when this option is set,
6248 unless the verbose logging is set. The main graphing area contains the
6249 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6250 the momentary loudness (400 milliseconds).
6252 More information about the Loudness Recommendation EBU R128 on
6253 @url{http://tech.ebu.ch/loudness}.
6255 The filter accepts the following named parameters:
6260 Activate the video output. The audio stream is passed unchanged whether this
6261 option is set or no. The video stream will be the first output stream if
6262 activated. Default is @code{0}.
6265 Set the video size. This option is for video only. Default and minimum
6266 resolution is @code{640x480}.
6269 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6270 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6271 other integer value between this range is allowed.
6275 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
6277 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6280 Run an analysis with @command{ffmpeg}:
6282 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6285 @section settb, asettb
6287 Set the timebase to use for the output frames timestamps.
6288 It is mainly useful for testing timebase configuration.
6290 It accepts in input an arithmetic expression representing a rational.
6291 The expression can contain the constants "AVTB" (the
6292 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
6295 The default value for the input is "intb".
6297 @subsection Examples
6301 Set the timebase to 1/25:
6307 Set the timebase to 1/10:
6313 Set the timebase to 1001/1000:
6319 Set the timebase to 2*intb:
6325 Set the default timebase value:
6333 Concatenate audio and video streams, joining them together one after the
6336 The filter works on segments of synchronized video and audio streams. All
6337 segments must have the same number of streams of each type, and that will
6338 also be the number of streams at output.
6340 The filter accepts the following named parameters:
6344 Set the number of segments. Default is 2.
6347 Set the number of output video streams, that is also the number of video
6348 streams in each segment. Default is 1.
6351 Set the number of output audio streams, that is also the number of video
6352 streams in each segment. Default is 0.
6355 Activate unsafe mode: do not fail if segments have a different format.
6359 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6360 @var{a} audio outputs.
6362 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6363 segment, in the same order as the outputs, then the inputs for the second
6366 Related streams do not always have exactly the same duration, for various
6367 reasons including codec frame size or sloppy authoring. For that reason,
6368 related synchronized streams (e.g. a video and its audio track) should be
6369 concatenated at once. The concat filter will use the duration of the longest
6370 stream in each segment (except the last one), and if necessary pad shorter
6371 audio streams with silence.
6373 For this filter to work correctly, all segments must start at timestamp 0.
6375 All corresponding streams must have the same parameters in all segments; the
6376 filtering system will automatically select a common pixel format for video
6377 streams, and a common sample format, sample rate and channel layout for
6378 audio streams, but other settings, such as resolution, must be converted
6379 explicitly by the user.
6381 Different frame rates are acceptable but will result in variable frame rate
6382 at output; be sure to configure the output file to handle it.
6387 Concatenate an opening, an episode and an ending, all in bilingual version
6388 (video in stream 0, audio in streams 1 and 2):
6390 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6391 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6392 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6393 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6397 Concatenate two parts, handling audio and video separately, using the
6398 (a)movie sources, and adjusting the resolution:
6400 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6401 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6402 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
6404 Note that a desync will happen at the stitch if the audio and video streams
6405 do not have exactly the same duration in the first file.
6409 @section showspectrum
6411 Convert input audio to a video output, representing the audio frequency
6414 The filter accepts the following named parameters:
6417 Specify the video size for the output. Default value is @code{640x512}.
6420 Specify if the spectrum should slide along the window. Default value is
6424 Specify display mode.
6426 It accepts the following values:
6429 all channels are displayed in the same row
6431 all channels are displayed in separate rows
6434 Default value is @samp{combined}.
6437 Specify display color mode.
6439 It accepts the following values:
6442 each channel is displayed in a separate color
6444 each channel is is displayed using the same color scheme
6447 Default value is @samp{channel}.
6450 Specify scale used for calculating intensity color values.
6452 It accepts the following values:
6457 square root, default
6464 Default value is @samp{sqrt}.
6467 Set saturation modifier for displayed colors. Negative values provide
6468 alternative color scheme. @code{0} is no saturation at all.
6469 Saturation must be in [-10.0, 10.0] range.
6470 Default value is @code{1}.
6473 The usage is very similar to the showwaves filter; see the examples in that
6478 Convert input audio to a video output, representing the samples waves.
6480 The filter accepts the following named parameters:
6485 Available values are:
6488 Draw a point for each sample.
6491 Draw a vertical line for each sample.
6494 Default value is @code{point}.
6497 Set the number of samples which are printed on the same column. A
6498 larger value will decrease the frame rate. Must be a positive
6499 integer. This option can be set only if the value for @var{rate}
6500 is not explicitly specified.
6503 Set the (approximate) output frame rate. This is done by setting the
6504 option @var{n}. Default value is "25".
6507 Specify the video size for the output. Default value is "600x240".
6510 Some examples follow.
6513 Output the input file audio and the corresponding video representation
6516 amovie=a.mp3,asplit[out0],showwaves[out1]
6520 Create a synthetic signal and show it with showwaves, forcing a
6521 framerate of 30 frames per second:
6523 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
6527 @c man end MULTIMEDIA FILTERS
6529 @chapter Multimedia Sources
6530 @c man begin MULTIMEDIA SOURCES
6532 Below is a description of the currently available multimedia sources.
6536 This is the same as @ref{movie} source, except it selects an audio
6542 Read audio and/or video stream(s) from a movie container.
6544 It accepts the syntax: @var{movie_name}[:@var{options}] where
6545 @var{movie_name} is the name of the resource to read (not necessarily
6546 a file but also a device or a stream accessed through some protocol),
6547 and @var{options} is an optional sequence of @var{key}=@var{value}
6548 pairs, separated by ":".
6550 The description of the accepted options follows.
6554 @item format_name, f
6555 Specifies the format assumed for the movie to read, and can be either
6556 the name of a container or an input device. If not specified the
6557 format is guessed from @var{movie_name} or by probing.
6559 @item seek_point, sp
6560 Specifies the seek point in seconds, the frames will be output
6561 starting from this seek point, the parameter is evaluated with
6562 @code{av_strtod} so the numerical value may be suffixed by an IS
6563 postfix. Default value is "0".
6566 Specifies the streams to read. Several streams can be specified,
6567 separated by "+". The source will then have as many outputs, in the
6568 same order. The syntax is explained in the ``Stream specifiers''
6569 section in the ffmpeg manual. Two special names, "dv" and "da" specify
6570 respectively the default (best suited) video and audio stream. Default
6571 is "dv", or "da" if the filter is called as "amovie".
6573 @item stream_index, si
6574 Specifies the index of the video stream to read. If the value is -1,
6575 the best suited video stream will be automatically selected. Default
6576 value is "-1". Deprecated. If the filter is called "amovie", it will select
6577 audio instead of video.
6580 Specifies how many times to read the stream in sequence.
6581 If the value is less than 1, the stream will be read again and again.
6582 Default value is "1".
6584 Note that when the movie is looped the source timestamps are not
6585 changed, so it will generate non monotonically increasing timestamps.
6588 This filter allows to overlay a second video on top of main input of
6589 a filtergraph as shown in this graph:
6591 input -----------> deltapts0 --> overlay --> output
6594 movie --> scale--> deltapts1 -------+
6597 Some examples follow.
6601 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
6602 on top of the input labelled as "in":
6604 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6605 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6609 Read from a video4linux2 device, and overlay it on top of the input
6612 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6613 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6617 Read the first video stream and the audio stream with id 0x81 from
6618 dvd.vob; the video is connected to the pad named "video" and the audio is
6619 connected to the pad named "audio":
6621 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
6625 @c man end MULTIMEDIA SOURCES