1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 This filtergraph splits the input stream in two streams, sends one
19 stream through the crop filter and the vflip filter before merging it
20 back with the other stream by overlaying it on top. You can use the
21 following command to achieve this:
24 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
27 The result will be that in output the top half of the video is mirrored
30 Filters in the same linear chain are separated by commas, and distinct
31 linear chains of filters are separated by semicolons. In our example,
32 @var{crop,vflip} are in one linear chain, @var{split} and
33 @var{overlay} are separately in another. The points where the linear
34 chains join are labelled by names enclosed in square brackets. In the
35 example, the split filter generates two outputs that are associated to
36 the labels @var{[main]} and @var{[tmp]}.
38 The stream sent to the second output of @var{split}, labelled as
39 @var{[tmp]}, is processed through the @var{crop} filter, which crops
40 away the lower half part of the video, and then vertically flipped. The
41 @var{overlay} filter takes in input the first unchanged output of the
42 split filter (which was labelled as @var{[main]}), and overlay on its
43 lower half the output generated by the @var{crop,vflip} filterchain.
45 Some filters take in input a list of parameters: they are specified
46 after the filter name and an equal sign, and are separated from each other
49 There exist so-called @var{source filters} that do not have an
50 audio/video input, and @var{sink filters} that will not have audio/video
53 @c man end FILTERING INTRODUCTION
56 @c man begin GRAPH2DOT
58 The @file{graph2dot} program included in the FFmpeg @file{tools}
59 directory can be used to parse a filtergraph description and issue a
60 corresponding textual representation in the dot language.
67 to see how to use @file{graph2dot}.
69 You can then pass the dot description to the @file{dot} program (from
70 the graphviz suite of programs) and obtain a graphical representation
73 For example the sequence of commands:
75 echo @var{GRAPH_DESCRIPTION} | \
76 tools/graph2dot -o graph.tmp && \
77 dot -Tpng graph.tmp -o graph.png && \
81 can be used to create and display an image representing the graph
82 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
83 a complete self-contained graph, with its inputs and outputs explicitly defined.
84 For example if your command line is of the form:
86 ffmpeg -i infile -vf scale=640:360 outfile
88 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
90 nullsrc,scale=640:360,nullsink
92 you may also need to set the @var{nullsrc} parameters and add a @var{format}
93 filter in order to simulate a specific input file.
97 @chapter Filtergraph description
98 @c man begin FILTERGRAPH DESCRIPTION
100 A filtergraph is a directed graph of connected filters. It can contain
101 cycles, and there can be multiple links between a pair of
102 filters. Each link has one input pad on one side connecting it to one
103 filter from which it takes its input, and one output pad on the other
104 side connecting it to the one filter accepting its output.
106 Each filter in a filtergraph is an instance of a filter class
107 registered in the application, which defines the features and the
108 number of input and output pads of the filter.
110 A filter with no input pads is called a "source", a filter with no
111 output pads is called a "sink".
113 @anchor{Filtergraph syntax}
114 @section Filtergraph syntax
116 A filtergraph can be represented using a textual representation, which is
117 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
118 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
119 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
120 @file{libavfilter/avfiltergraph.h}.
122 A filterchain consists of a sequence of connected filters, each one
123 connected to the previous one in the sequence. A filterchain is
124 represented by a list of ","-separated filter descriptions.
126 A filtergraph consists of a sequence of filterchains. A sequence of
127 filterchains is represented by a list of ";"-separated filterchain
130 A filter is represented by a string of the form:
131 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
133 @var{filter_name} is the name of the filter class of which the
134 described filter is an instance of, and has to be the name of one of
135 the filter classes registered in the program.
136 The name of the filter class is optionally followed by a string
139 @var{arguments} is a string which contains the parameters used to
140 initialize the filter instance. It may have one of the following forms:
144 A ':'-separated list of @var{key=value} pairs.
147 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
148 the option names in the order they are declared. E.g. the @code{fade} filter
149 declares three options in this order -- @option{type}, @option{start_frame} and
150 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
151 @var{in} is assigned to the option @option{type}, @var{0} to
152 @option{start_frame} and @var{30} to @option{nb_frames}.
155 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
156 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
157 follow the same constraints order of the previous point. The following
158 @var{key=value} pairs can be set in any preferred order.
162 If the option value itself is a list of items (e.g. the @code{format} filter
163 takes a list of pixel formats), the items in the list are usually separated by
166 The list of arguments can be quoted using the character "'" as initial
167 and ending mark, and the character '\' for escaping the characters
168 within the quoted text; otherwise the argument string is considered
169 terminated when the next special character (belonging to the set
170 "[]=;,") is encountered.
172 The name and arguments of the filter are optionally preceded and
173 followed by a list of link labels.
174 A link label allows to name a link and associate it to a filter output
175 or input pad. The preceding labels @var{in_link_1}
176 ... @var{in_link_N}, are associated to the filter input pads,
177 the following labels @var{out_link_1} ... @var{out_link_M}, are
178 associated to the output pads.
180 When two link labels with the same name are found in the
181 filtergraph, a link between the corresponding input and output pad is
184 If an output pad is not labelled, it is linked by default to the first
185 unlabelled input pad of the next filter in the filterchain.
186 For example in the filterchain:
188 nullsrc, split[L1], [L2]overlay, nullsink
190 the split filter instance has two output pads, and the overlay filter
191 instance two input pads. The first output pad of split is labelled
192 "L1", the first input pad of overlay is labelled "L2", and the second
193 output pad of split is linked to the second input pad of overlay,
194 which are both unlabelled.
196 In a complete filterchain all the unlabelled filter input and output
197 pads must be connected. A filtergraph is considered valid if all the
198 filter input and output pads of all the filterchains are connected.
200 Libavfilter will automatically insert scale filters where format
201 conversion is required. It is possible to specify swscale flags
202 for those automatically inserted scalers by prepending
203 @code{sws_flags=@var{flags};}
204 to the filtergraph description.
206 Follows a BNF description for the filtergraph syntax:
208 @var{NAME} ::= sequence of alphanumeric characters and '_'
209 @var{LINKLABEL} ::= "[" @var{NAME} "]"
210 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
211 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
212 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
213 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
214 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
217 @section Notes on filtergraph escaping
219 Some filter arguments require the use of special characters, typically
220 @code{:} to separate key=value pairs in a named options list. In this
221 case the user should perform a first level escaping when specifying
222 the filter arguments. For example, consider the following literal
223 string to be embedded in the @ref{drawtext} filter arguments:
225 this is a 'string': may contain one, or more, special characters
228 Since @code{:} is special for the filter arguments syntax, it needs to
229 be escaped, so you get:
231 text=this is a \'string\'\: may contain one, or more, special characters
234 A second level of escaping is required when embedding the filter
235 arguments in a filtergraph description, in order to escape all the
236 filtergraph special characters. Thus the example above becomes:
238 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
241 Finally an additional level of escaping may be needed when writing the
242 filtergraph description in a shell command, which depends on the
243 escaping rules of the adopted shell. For example, assuming that
244 @code{\} is special and needs to be escaped with another @code{\}, the
245 previous string will finally result in:
247 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
250 Sometimes, it might be more convenient to employ quoting in place of
251 escaping. For example the string:
253 Caesar: tu quoque, Brute, fili mi
256 Can be quoted in the filter arguments as:
258 text='Caesar: tu quoque, Brute, fili mi'
261 And finally inserted in a filtergraph like:
263 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
266 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
267 for more information about the escaping and quoting rules adopted by
270 @c man end FILTERGRAPH DESCRIPTION
272 @chapter Audio Filters
273 @c man begin AUDIO FILTERS
275 When you configure your FFmpeg build, you can disable any of the
276 existing filters using @code{--disable-filters}.
277 The configure output will show the audio filters included in your
280 Below is a description of the currently available audio filters.
284 Convert the input audio format to the specified formats.
286 @emph{This filter is deprecated. Use @ref{aformat} instead.}
288 The filter accepts a string of the form:
289 "@var{sample_format}:@var{channel_layout}".
291 @var{sample_format} specifies the sample format, and can be a string or the
292 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
293 suffix for a planar sample format.
295 @var{channel_layout} specifies the channel layout, and can be a string
296 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
298 The special parameter "auto", signifies that the filter will
299 automatically select the output format depending on the output filter.
305 Convert input to float, planar, stereo:
311 Convert input to unsigned 8-bit, automatically select out channel layout:
319 Apply a two-pole all-pass filter with central frequency (in Hz)
320 @var{frequency}, and filter-width @var{width}.
321 An all-pass filter changes the audio's frequency to phase relationship
322 without changing its frequency to amplitude relationship.
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.
334 Set method to specify band-width of filter.
347 Specify the band-width of a filter in width_type units.
352 Apply a high-pass filter with 3dB point frequency.
353 The filter can be either single-pole, or double-pole (the default).
354 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
356 The filter accepts parameters as a list of @var{key}=@var{value}
357 pairs, separated by ":".
359 A description of the accepted parameters follows.
363 Set frequency in Hz. Default is 3000.
366 Set number of poles. Default is 2.
369 Set method to specify band-width of filter.
382 Specify the band-width of a filter in width_type units.
383 Applies only to double-pole filter.
384 The default is 0.707q and gives a Butterworth response.
389 Apply a low-pass filter with 3dB point frequency.
390 The filter can be either single-pole or double-pole (the default).
391 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
393 The filter accepts parameters as a list of @var{key}=@var{value}
394 pairs, separated by ":".
396 A description of the accepted parameters follows.
400 Set frequency in Hz. Default is 500.
403 Set number of poles. Default is 2.
406 Set method to specify band-width of filter.
419 Specify the band-width of a filter in width_type units.
420 Applies only to double-pole filter.
421 The default is 0.707q and gives a Butterworth response.
426 Boost or cut the bass (lower) frequencies of the audio using a two-pole
427 shelving filter with a response similar to that of a standard
428 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
430 The filter accepts parameters as a list of @var{key}=@var{value}
431 pairs, separated by ":".
433 A description of the accepted parameters follows.
437 Give the gain at 0 Hz. Its useful range is about -20
438 (for a large cut) to +20 (for a large boost).
439 Beware of clipping when using a positive gain.
442 Set the filter's central frequency and so can be used
443 to extend or reduce the frequency range to be boosted or cut.
444 The default value is @code{100} Hz.
447 Set method to specify band-width of filter.
460 Determine how steep is the filter's shelf transition.
465 Apply telecine process to the video.
467 This filter accepts the following options:
476 The default value is @code{top}.
480 A string of numbers representing the pulldown pattern you wish to apply.
481 The default value is @code{23}.
485 Some typical patterns:
490 24p: 2332 (preferred)
497 24p: 222222222223 ("Euro pulldown")
504 Boost or cut treble (upper) frequencies of the audio using a two-pole
505 shelving filter with a response similar to that of a standard
506 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
508 The filter accepts parameters as a list of @var{key}=@var{value}
509 pairs, separated by ":".
511 A description of the accepted parameters follows.
515 Give the gain at whichever is the lower of ~22 kHz and the
516 Nyquist frequency. Its useful range is about -20 (for a large cut)
517 to +20 (for a large boost). Beware of clipping when using a positive gain.
520 Set the filter's central frequency and so can be used
521 to extend or reduce the frequency range to be boosted or cut.
522 The default value is @code{3000} Hz.
525 Set method to specify band-width of filter.
538 Determine how steep is the filter's shelf transition.
543 Apply a two-pole Butterworth band-pass filter with central
544 frequency @var{frequency}, and (3dB-point) band-width width.
545 The @var{csg} option selects a constant skirt gain (peak gain = Q)
546 instead of the default: constant 0dB peak gain.
547 The filter roll off at 6dB per octave (20dB per decade).
549 The filter accepts parameters as a list of @var{key}=@var{value}
550 pairs, separated by ":".
552 A description of the accepted parameters follows.
556 Set the filter's central frequency. Default is @code{3000}.
559 Constant skirt gain if set to 1. Defaults to 0.
562 Set method to specify band-width of filter.
575 Specify the band-width of a filter in width_type units.
580 Apply a two-pole Butterworth band-reject filter with central
581 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
582 The filter roll off at 6dB per octave (20dB per decade).
584 The filter accepts parameters as a list of @var{key}=@var{value}
585 pairs, separated by ":".
587 A description of the accepted parameters follows.
591 Set the filter's central frequency. Default is @code{3000}.
594 Set method to specify band-width of filter.
607 Specify the band-width of a filter in width_type units.
612 Apply a biquad IIR filter with the given coefficients.
613 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
614 are the numerator and denominator coefficients respectively.
618 Apply a two-pole peaking equalisation (EQ) filter. With this
619 filter, the signal-level at and around a selected frequency can
620 be increased or decreased, whilst (unlike bandpass and bandreject
621 filters) that at all other frequencies is unchanged.
623 In order to produce complex equalisation curves, this filter can
624 be given several times, each with a different central frequency.
626 The filter accepts parameters as a list of @var{key}=@var{value}
627 pairs, separated by ":".
629 A description of the accepted parameters follows.
633 Set the filter's central frequency in Hz.
636 Set method to specify band-width of filter.
649 Specify the band-width of a filter in width_type units.
652 Set the required gain or attenuation in dB.
653 Beware of clipping when using a positive gain.
658 Apply fade-in/out effect to input audio.
660 A description of the accepted parameters follows.
664 Specify the effect type, can be either @code{in} for fade-in, or
665 @code{out} for a fade-out effect. Default is @code{in}.
667 @item start_sample, ss
668 Specify the number of the start sample for starting to apply the fade
669 effect. Default is 0.
672 Specify the number of samples for which the fade effect has to last. At
673 the end of the fade-in effect the output audio will have the same
674 volume as the input audio, at the end of the fade-out transition
675 the output audio will be silence. Default is 44100.
678 Specify time in seconds for starting to apply the fade
679 effect. Default is 0.
680 If set this option is used instead of @var{start_sample} one.
683 Specify the number of seconds for which the fade effect has to last. At
684 the end of the fade-in effect the output audio will have the same
685 volume as the input audio, at the end of the fade-out transition
686 the output audio will be silence. Default is 0.
687 If set this option is used instead of @var{nb_samples} one.
690 Set curve for fade transition.
692 It accepts the following values:
695 select triangular, linear slope (default)
697 select quarter of sine wave
699 select half of sine wave
701 select exponential sine wave
705 select inverted parabola
721 Fade in first 15 seconds of audio:
727 Fade out last 25 seconds of a 900 seconds audio:
729 afade=t=out:ss=875:d=25
736 Set output format constraints for the input audio. The framework will
737 negotiate the most appropriate format to minimize conversions.
739 The filter accepts the following named parameters:
743 A '|'-separated list of requested sample formats.
746 A '|'-separated list of requested sample rates.
748 @item channel_layouts
749 A '|'-separated list of requested channel layouts.
753 If a parameter is omitted, all values are allowed.
755 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
757 aformat=sample_fmts=u8|s16:channel_layouts=stereo
762 Merge two or more audio streams into a single multi-channel stream.
764 The filter accepts the following options:
769 Set the number of inputs. Default is 2.
773 If the channel layouts of the inputs are disjoint, and therefore compatible,
774 the channel layout of the output will be set accordingly and the channels
775 will be reordered as necessary. If the channel layouts of the inputs are not
776 disjoint, the output will have all the channels of the first input then all
777 the channels of the second input, in that order, and the channel layout of
778 the output will be the default value corresponding to the total number of
781 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
782 is FC+BL+BR, then the output will be in 5.1, with the channels in the
783 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
784 first input, b1 is the first channel of the second input).
786 On the other hand, if both input are in stereo, the output channels will be
787 in the default order: a1, a2, b1, b2, and the channel layout will be
788 arbitrarily set to 4.0, which may or may not be the expected value.
790 All inputs must have the same sample rate, and format.
792 If inputs do not have the same duration, the output will stop with the
799 Merge two mono files into a stereo stream:
801 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
808 amovie=input.mkv:si=0 [a0];
809 amovie=input.mkv:si=1 [a1];
810 amovie=input.mkv:si=2 [a2];
811 amovie=input.mkv:si=3 [a3];
812 amovie=input.mkv:si=4 [a4];
813 amovie=input.mkv:si=5 [a5];
814 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
820 Mixes multiple audio inputs into a single output.
824 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
826 will mix 3 input audio streams to a single output with the same duration as the
827 first input and a dropout transition time of 3 seconds.
829 The filter accepts the following named parameters:
833 Number of inputs. If unspecified, it defaults to 2.
836 How to determine the end-of-stream.
840 Duration of longest input. (default)
843 Duration of shortest input.
846 Duration of first input.
850 @item dropout_transition
851 Transition time, in seconds, for volume renormalization when an input
852 stream ends. The default value is 2 seconds.
858 Pass the audio source unchanged to the output.
862 Pad the end of a audio stream with silence, this can be used together with
863 -shortest to extend audio streams to the same length as the video stream.
868 Resample the input audio to the specified parameters, using the
869 libswresample library. If none are specified then the filter will
870 automatically convert between its input and output.
872 This filter is also able to stretch/squeeze the audio data to make it match
873 the timestamps or to inject silence / cut out audio to make it match the
874 timestamps, do a combination of both or do neither.
876 The filter accepts the syntax
877 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
878 expresses a sample rate and @var{resampler_options} is a list of
879 @var{key}=@var{value} pairs, separated by ":". See the
880 ffmpeg-resampler manual for the complete list of supported options.
886 Resample the input audio to 44100Hz:
892 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
893 samples per second compensation:
899 @section asetnsamples
901 Set the number of samples per each output audio frame.
903 The last output packet may contain a different number of samples, as
904 the filter will flush all the remaining samples when the input audio
907 The filter accepts the following options:
911 @item nb_out_samples, n
912 Set the number of frames per each output audio frame. The number is
913 intended as the number of samples @emph{per each channel}.
914 Default value is 1024.
917 If set to 1, the filter will pad the last audio frame with zeroes, so
918 that the last frame will contain the same number of samples as the
919 previous ones. Default value is 1.
922 For example, to set the number of per-frame samples to 1234 and
923 disable padding for the last frame, use:
925 asetnsamples=n=1234:p=0
930 Show a line containing various information for each input audio frame.
931 The input audio is not modified.
933 The shown line contains a sequence of key/value pairs of the form
934 @var{key}:@var{value}.
936 A description of each shown parameter follows:
940 sequential number of the input frame, starting from 0
943 Presentation timestamp of the input frame, in time base units; the time base
944 depends on the filter input pad, and is usually 1/@var{sample_rate}.
947 presentation timestamp of the input frame in seconds
950 position of the frame in the input stream, -1 if this information in
951 unavailable and/or meaningless (for example in case of synthetic audio)
960 sample rate for the audio frame
963 number of samples (per channel) in the frame
966 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
967 the data is treated as if all the planes were concatenated.
969 @item plane_checksums
970 A list of Adler-32 checksums for each data plane.
975 Split input audio into several identical outputs.
977 The filter accepts a single parameter which specifies the number of outputs. If
978 unspecified, it defaults to 2.
982 [in] asplit [out0][out1]
985 will create two separate outputs from the same input.
987 To create 3 or more outputs, you need to specify the number of
990 [in] asplit=3 [out0][out1][out2]
994 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
996 will create 5 copies of the input audio.
1001 Forward two audio streams and control the order the buffers are forwarded.
1003 The filter accepts the following options:
1007 Set the expression deciding which stream should be
1008 forwarded next: if the result is negative, the first stream is forwarded; if
1009 the result is positive or zero, the second stream is forwarded. It can use
1010 the following variables:
1014 number of buffers forwarded so far on each stream
1016 number of samples forwarded so far on each stream
1018 current timestamp of each stream
1021 The default value is @code{t1-t2}, which means to always forward the stream
1022 that has a smaller timestamp.
1025 @subsection Examples
1027 Stress-test @code{amerge} by randomly sending buffers on the wrong
1028 input, while avoiding too much of a desynchronization:
1030 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1031 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1039 The filter accepts exactly one parameter, the audio tempo. If not
1040 specified then the filter will assume nominal 1.0 tempo. Tempo must
1041 be in the [0.5, 2.0] range.
1043 @subsection Examples
1047 Slow down audio to 80% tempo:
1053 To speed up audio to 125% tempo:
1061 Make audio easier to listen to on headphones.
1063 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1064 so that when listened to on headphones the stereo image is moved from
1065 inside your head (standard for headphones) to outside and in front of
1066 the listener (standard for speakers).
1072 Mix channels with specific gain levels. The filter accepts the output
1073 channel layout followed by a set of channels definitions.
1075 This filter is also designed to remap efficiently the channels of an audio
1078 The filter accepts parameters of the form:
1079 "@var{l}:@var{outdef}:@var{outdef}:..."
1083 output channel layout or number of channels
1086 output channel specification, of the form:
1087 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1090 output channel to define, either a channel name (FL, FR, etc.) or a channel
1091 number (c0, c1, etc.)
1094 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1097 input channel to use, see out_name for details; it is not possible to mix
1098 named and numbered input channels
1101 If the `=' in a channel specification is replaced by `<', then the gains for
1102 that specification will be renormalized so that the total is 1, thus
1103 avoiding clipping noise.
1105 @subsection Mixing examples
1107 For example, if you want to down-mix from stereo to mono, but with a bigger
1108 factor for the left channel:
1110 pan=1:c0=0.9*c0+0.1*c1
1113 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1114 7-channels surround:
1116 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1119 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1120 that should be preferred (see "-ac" option) unless you have very specific
1123 @subsection Remapping examples
1125 The channel remapping will be effective if, and only if:
1128 @item gain coefficients are zeroes or ones,
1129 @item only one input per channel output,
1132 If all these conditions are satisfied, the filter will notify the user ("Pure
1133 channel mapping detected"), and use an optimized and lossless method to do the
1136 For example, if you have a 5.1 source and want a stereo audio stream by
1137 dropping the extra channels:
1139 pan="stereo: c0=FL : c1=FR"
1142 Given the same source, you can also switch front left and front right channels
1143 and keep the input channel layout:
1145 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1148 If the input is a stereo audio stream, you can mute the front left channel (and
1149 still keep the stereo channel layout) with:
1154 Still with a stereo audio stream input, you can copy the right channel in both
1155 front left and right:
1157 pan="stereo: c0=FR : c1=FR"
1160 @section silencedetect
1162 Detect silence in an audio stream.
1164 This filter logs a message when it detects that the input audio volume is less
1165 or equal to a noise tolerance value for a duration greater or equal to the
1166 minimum detected noise duration.
1168 The printed times and duration are expressed in seconds.
1170 The filter accepts the following options:
1174 Set silence duration until notification (default is 2 seconds).
1177 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1178 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1181 @subsection Examples
1185 Detect 5 seconds of silence with -50dB noise tolerance:
1187 silencedetect=n=-50dB:d=5
1191 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1192 tolerance in @file{silence.mp3}:
1194 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1199 Synchronize audio data with timestamps by squeezing/stretching it and/or
1200 dropping samples/adding silence when needed.
1202 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1204 The filter accepts the following named parameters:
1208 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1209 by default. When disabled, time gaps are covered with silence.
1212 Minimum difference between timestamps and audio data (in seconds) to trigger
1213 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1214 this filter, try setting this parameter to 0.
1217 Maximum compensation in samples per second. Relevant only with compensate=1.
1221 Assume the first pts should be this value. The time base is 1 / sample rate.
1222 This allows for padding/trimming at the start of stream. By default, no
1223 assumption is made about the first frame's expected pts, so no padding or
1224 trimming is done. For example, this could be set to 0 to pad the beginning with
1225 silence if an audio stream starts after the video stream or to trim any samples
1226 with a negative pts due to encoder delay.
1230 @section channelsplit
1231 Split each channel in input audio stream into a separate output stream.
1233 This filter accepts the following named parameters:
1235 @item channel_layout
1236 Channel layout of the input stream. Default is "stereo".
1239 For example, assuming a stereo input MP3 file
1241 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1243 will create an output Matroska file with two audio streams, one containing only
1244 the left channel and the other the right channel.
1246 To split a 5.1 WAV file into per-channel files
1248 ffmpeg -i in.wav -filter_complex
1249 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1250 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1251 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1256 Remap input channels to new locations.
1258 This filter accepts the following named parameters:
1260 @item channel_layout
1261 Channel layout of the output stream.
1264 Map channels from input to output. The argument is a '|'-separated list of
1265 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1266 @var{in_channel} form. @var{in_channel} can be either the name of the input
1267 channel (e.g. FL for front left) or its index in the input channel layout.
1268 @var{out_channel} is the name of the output channel or its index in the output
1269 channel layout. If @var{out_channel} is not given then it is implicitly an
1270 index, starting with zero and increasing by one for each mapping.
1273 If no mapping is present, the filter will implicitly map input channels to
1274 output channels preserving index.
1276 For example, assuming a 5.1+downmix input MOV file
1278 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1280 will create an output WAV file tagged as stereo from the downmix channels of
1283 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1285 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1289 Join multiple input streams into one multi-channel stream.
1291 The filter accepts the following named parameters:
1295 Number of input streams. Defaults to 2.
1297 @item channel_layout
1298 Desired output channel layout. Defaults to stereo.
1301 Map channels from inputs to output. The argument is a '|'-separated list of
1302 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1303 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1304 can be either the name of the input channel (e.g. FL for front left) or its
1305 index in the specified input stream. @var{out_channel} is the name of the output
1309 The filter will attempt to guess the mappings when those are not specified
1310 explicitly. It does so by first trying to find an unused matching input channel
1311 and if that fails it picks the first unused input channel.
1313 E.g. to join 3 inputs (with properly set channel layouts)
1315 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1318 To build a 5.1 output from 6 single-channel streams:
1320 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1321 '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'
1326 Convert the audio sample format, sample rate and channel layout. This filter is
1327 not meant to be used directly.
1331 Adjust the input audio volume.
1333 The filter accepts the following named parameters. If the key of the
1334 first options is omitted, the arguments are interpreted according to
1335 the following syntax:
1337 volume=@var{volume}:@var{precision}
1343 Expresses how the audio volume will be increased or decreased.
1345 Output values are clipped to the maximum value.
1347 The output audio volume is given by the relation:
1349 @var{output_volume} = @var{volume} * @var{input_volume}
1352 Default value for @var{volume} is 1.0.
1355 Set the mathematical precision.
1357 This determines which input sample formats will be allowed, which affects the
1358 precision of the volume scaling.
1362 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1364 32-bit floating-point; limits input sample format to FLT. (default)
1366 64-bit floating-point; limits input sample format to DBL.
1370 @subsection Examples
1374 Halve the input audio volume:
1378 volume=volume=-6.0206dB
1381 In all the above example the named key for @option{volume} can be
1382 omitted, for example like in:
1388 Increase input audio power by 6 decibels using fixed-point precision:
1390 volume=volume=6dB:precision=fixed
1394 @section volumedetect
1396 Detect the volume of the input video.
1398 The filter has no parameters. The input is not modified. Statistics about
1399 the volume will be printed in the log when the input stream end is reached.
1401 In particular it will show the mean volume (root mean square), maximum
1402 volume (on a per-sample basis), and the beginning of an histogram of the
1403 registered volume values (from the maximum value to a cumulated 1/1000 of
1406 All volumes are in decibels relative to the maximum PCM value.
1408 @subsection Examples
1410 Here is an excerpt of the output:
1412 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1413 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1414 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1415 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1416 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1417 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1418 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1419 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1420 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1426 The mean square energy is approximately -27 dB, or 10^-2.7.
1428 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1430 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1433 In other words, raising the volume by +4 dB does not cause any clipping,
1434 raising it by +5 dB causes clipping for 6 samples, etc.
1436 @c man end AUDIO FILTERS
1438 @chapter Audio Sources
1439 @c man begin AUDIO SOURCES
1441 Below is a description of the currently available audio sources.
1445 Buffer audio frames, and make them available to the filter chain.
1447 This source is mainly intended for a programmatic use, in particular
1448 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1450 It accepts the following named parameters:
1455 Timebase which will be used for timestamps of submitted frames. It must be
1456 either a floating-point number or in @var{numerator}/@var{denominator} form.
1459 The sample rate of the incoming audio buffers.
1462 The sample format of the incoming audio buffers.
1463 Either a sample format name or its corresponging integer representation from
1464 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1466 @item channel_layout
1467 The channel layout of the incoming audio buffers.
1468 Either a channel layout name from channel_layout_map in
1469 @file{libavutil/channel_layout.c} or its corresponding integer representation
1470 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1473 The number of channels of the incoming audio buffers.
1474 If both @var{channels} and @var{channel_layout} are specified, then they
1479 @subsection Examples
1482 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1485 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1486 Since the sample format with name "s16p" corresponds to the number
1487 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1490 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1495 Generate an audio signal specified by an expression.
1497 This source accepts in input one or more expressions (one for each
1498 channel), which are evaluated and used to generate a corresponding
1501 This source accepts the following options:
1505 Set the '|'-separated expressions list for each separate channel. In case the
1506 @option{channel_layout} option is not specified, the selected channel layout
1507 depends on the number of provided expressions.
1509 @item channel_layout, c
1510 Set the channel layout. The number of channels in the specified layout
1511 must be equal to the number of specified expressions.
1514 Set the minimum duration of the sourced audio. See the function
1515 @code{av_parse_time()} for the accepted format.
1516 Note that the resulting duration may be greater than the specified
1517 duration, as the generated audio is always cut at the end of a
1520 If not specified, or the expressed duration is negative, the audio is
1521 supposed to be generated forever.
1524 Set the number of samples per channel per each output frame,
1527 @item sample_rate, s
1528 Specify the sample rate, default to 44100.
1531 Each expression in @var{exprs} can contain the following constants:
1535 number of the evaluated sample, starting from 0
1538 time of the evaluated sample expressed in seconds, starting from 0
1545 @subsection Examples
1555 Generate a sin signal with frequency of 440 Hz, set sample rate to
1558 aevalsrc="sin(440*2*PI*t):s=8000"
1562 Generate a two channels signal, specify the channel layout (Front
1563 Center + Back Center) explicitly:
1565 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
1569 Generate white noise:
1571 aevalsrc="-2+random(0)"
1575 Generate an amplitude modulated signal:
1577 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1581 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1583 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
1590 Null audio source, return unprocessed audio frames. It is mainly useful
1591 as a template and to be employed in analysis / debugging tools, or as
1592 the source for filters which ignore the input data (for example the sox
1595 This source accepts the following options:
1599 @item channel_layout, cl
1601 Specify the channel layout, and can be either an integer or a string
1602 representing a channel layout. The default value of @var{channel_layout}
1605 Check the channel_layout_map definition in
1606 @file{libavutil/channel_layout.c} for the mapping between strings and
1607 channel layout values.
1609 @item sample_rate, r
1610 Specify the sample rate, and defaults to 44100.
1613 Set the number of samples per requested frames.
1617 @subsection Examples
1621 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1623 anullsrc=r=48000:cl=4
1627 Do the same operation with a more obvious syntax:
1629 anullsrc=r=48000:cl=mono
1634 Buffer audio frames, and make them available to the filter chain.
1636 This source is not intended to be part of user-supplied graph descriptions but
1637 for insertion by calling programs through the interface defined in
1638 @file{libavfilter/buffersrc.h}.
1640 It accepts the following named parameters:
1644 Timebase which will be used for timestamps of submitted frames. It must be
1645 either a floating-point number or in @var{numerator}/@var{denominator} form.
1651 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1653 @item channel_layout
1654 Channel layout of the audio data, in the form that can be accepted by
1655 @code{av_get_channel_layout()}.
1658 All the parameters need to be explicitly defined.
1662 Synthesize a voice utterance using the libflite library.
1664 To enable compilation of this filter you need to configure FFmpeg with
1665 @code{--enable-libflite}.
1667 Note that the flite library is not thread-safe.
1669 The filter accepts the following options:
1674 If set to 1, list the names of the available voices and exit
1675 immediately. Default value is 0.
1678 Set the maximum number of samples per frame. Default value is 512.
1681 Set the filename containing the text to speak.
1684 Set the text to speak.
1687 Set the voice to use for the speech synthesis. Default value is
1688 @code{kal}. See also the @var{list_voices} option.
1691 @subsection Examples
1695 Read from file @file{speech.txt}, and synthetize the text using the
1696 standard flite voice:
1698 flite=textfile=speech.txt
1702 Read the specified text selecting the @code{slt} voice:
1704 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1708 Input text to ffmpeg:
1710 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1714 Make @file{ffplay} speak the specified text, using @code{flite} and
1715 the @code{lavfi} device:
1717 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1721 For more information about libflite, check:
1722 @url{http://www.speech.cs.cmu.edu/flite/}
1726 Generate an audio signal made of a sine wave with amplitude 1/8.
1728 The audio signal is bit-exact.
1730 The filter accepts the following options:
1735 Set the carrier frequency. Default is 440 Hz.
1737 @item beep_factor, b
1738 Enable a periodic beep every second with frequency @var{beep_factor} times
1739 the carrier frequency. Default is 0, meaning the beep is disabled.
1741 @item sample_rate, s
1742 Specify the sample rate, default is 44100.
1745 Specify the duration of the generated audio stream.
1747 @item samples_per_frame
1748 Set the number of samples per output frame, default is 1024.
1751 @subsection Examples
1756 Generate a simple 440 Hz sine wave:
1762 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1766 sine=frequency=220:beep_factor=4:duration=5
1771 @c man end AUDIO SOURCES
1773 @chapter Audio Sinks
1774 @c man begin AUDIO SINKS
1776 Below is a description of the currently available audio sinks.
1778 @section abuffersink
1780 Buffer audio frames, and make them available to the end of filter chain.
1782 This sink is mainly intended for programmatic use, in particular
1783 through the interface defined in @file{libavfilter/buffersink.h}.
1785 It requires a pointer to an AVABufferSinkContext structure, which
1786 defines the incoming buffers' formats, to be passed as the opaque
1787 parameter to @code{avfilter_init_filter} for initialization.
1791 Null audio sink, do absolutely nothing with the input audio. It is
1792 mainly useful as a template and to be employed in analysis / debugging
1795 @section abuffersink
1796 This sink is intended for programmatic use. Frames that arrive on this sink can
1797 be retrieved by the calling program using the interface defined in
1798 @file{libavfilter/buffersink.h}.
1800 This filter accepts no parameters.
1802 @c man end AUDIO SINKS
1804 @chapter Video Filters
1805 @c man begin VIDEO FILTERS
1807 When you configure your FFmpeg build, you can disable any of the
1808 existing filters using @code{--disable-filters}.
1809 The configure output will show the video filters included in your
1812 Below is a description of the currently available video filters.
1814 @section alphaextract
1816 Extract the alpha component from the input as a grayscale video. This
1817 is especially useful with the @var{alphamerge} filter.
1821 Add or replace the alpha component of the primary input with the
1822 grayscale value of a second input. This is intended for use with
1823 @var{alphaextract} to allow the transmission or storage of frame
1824 sequences that have alpha in a format that doesn't support an alpha
1827 For example, to reconstruct full frames from a normal YUV-encoded video
1828 and a separate video created with @var{alphaextract}, you might use:
1830 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1833 Since this filter is designed for reconstruction, it operates on frame
1834 sequences without considering timestamps, and terminates when either
1835 input reaches end of stream. This will cause problems if your encoding
1836 pipeline drops frames. If you're trying to apply an image as an
1837 overlay to a video stream, consider the @var{overlay} filter instead.
1841 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1842 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1843 Substation Alpha) subtitles files.
1847 Compute the bounding box for the non-black pixels in the input frame
1850 This filter computes the bounding box containing all the pixels with a
1851 luminance value greater than the minimum allowed value.
1852 The parameters describing the bounding box are printed on the filter
1855 @section blackdetect
1857 Detect video intervals that are (almost) completely black. Can be
1858 useful to detect chapter transitions, commercials, or invalid
1859 recordings. Output lines contains the time for the start, end and
1860 duration of the detected black interval expressed in seconds.
1862 In order to display the output lines, you need to set the loglevel at
1863 least to the AV_LOG_INFO value.
1865 The filter accepts the following options:
1868 @item black_min_duration, d
1869 Set the minimum detected black duration expressed in seconds. It must
1870 be a non-negative floating point number.
1872 Default value is 2.0.
1874 @item picture_black_ratio_th, pic_th
1875 Set the threshold for considering a picture "black".
1876 Express the minimum value for the ratio:
1878 @var{nb_black_pixels} / @var{nb_pixels}
1881 for which a picture is considered black.
1882 Default value is 0.98.
1884 @item pixel_black_th, pix_th
1885 Set the threshold for considering a pixel "black".
1887 The threshold expresses the maximum pixel luminance value for which a
1888 pixel is considered "black". The provided value is scaled according to
1889 the following equation:
1891 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1894 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1895 the input video format, the range is [0-255] for YUV full-range
1896 formats and [16-235] for YUV non full-range formats.
1898 Default value is 0.10.
1901 The following example sets the maximum pixel threshold to the minimum
1902 value, and detects only black intervals of 2 or more seconds:
1904 blackdetect=d=2:pix_th=0.00
1909 Detect frames that are (almost) completely black. Can be useful to
1910 detect chapter transitions or commercials. Output lines consist of
1911 the frame number of the detected frame, the percentage of blackness,
1912 the position in the file if known or -1 and the timestamp in seconds.
1914 In order to display the output lines, you need to set the loglevel at
1915 least to the AV_LOG_INFO value.
1917 The filter accepts parameters as a list of @var{key}=@var{value}
1918 pairs, separated by ":". If the key of the first options is omitted,
1919 the arguments are interpreted according to the syntax
1920 blackframe[=@var{amount}[:@var{threshold}]].
1922 The filter accepts the following options:
1927 The percentage of the pixels that have to be below the threshold, defaults to
1931 Threshold below which a pixel value is considered black, defaults to 32.
1937 Blend two video frames into each other.
1939 It takes two input streams and outputs one stream, the first input is the
1940 "top" layer and second input is "bottom" layer.
1941 Output terminates when shortest input terminates.
1943 A description of the accepted options follows.
1951 Set blend mode for specific pixel component or all pixel components in case
1952 of @var{all_mode}. Default value is @code{normal}.
1954 Available values for component modes are:
1987 Set blend opacity for specific pixel component or all pixel components in case
1988 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1995 Set blend expression for specific pixel component or all pixel components in case
1996 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1998 The expressions can use the following variables:
2002 The sequential number of the filtered frame, starting from @code{0}.
2006 the coordinates of the current sample
2010 the width and height of currently filtered plane
2014 Width and height scale depending on the currently filtered plane. It is the
2015 ratio between the corresponding luma plane number of pixels and the current
2016 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2017 @code{0.5,0.5} for chroma planes.
2020 Time of the current frame, expressed in seconds.
2023 Value of pixel component at current location for first video frame (top layer).
2026 Value of pixel component at current location for second video frame (bottom layer).
2030 @subsection Examples
2034 Apply transition from bottom layer to top layer in first 10 seconds:
2036 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2040 Apply 1x1 checkerboard effect:
2042 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2048 Apply boxblur algorithm to the input video.
2050 The filter accepts parameters as a list of @var{key}=@var{value}
2051 pairs, separated by ":". If the key of the first options is omitted,
2052 the arguments are interpreted according to the syntax
2053 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2055 This filter accepts the following options:
2068 A description of the accepted options follows.
2071 @item luma_radius, lr
2072 @item chroma_radius, cr
2073 @item alpha_radius, ar
2074 Set an expression for the box radius in pixels used for blurring the
2075 corresponding input plane.
2077 The radius value must be a non-negative number, and must not be
2078 greater than the value of the expression @code{min(w,h)/2} for the
2079 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2082 Default value for @option{luma_radius} is "2". If not specified,
2083 @option{chroma_radius} and @option{alpha_radius} default to the
2084 corresponding value set for @option{luma_radius}.
2086 The expressions can contain the following constants:
2089 the input width and height in pixels
2092 the input chroma image width and height in pixels
2095 horizontal and vertical chroma subsample values. For example for the
2096 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2099 @item luma_power, lp
2100 @item chroma_power, cp
2101 @item alpha_power, ap
2102 Specify how many times the boxblur filter is applied to the
2103 corresponding plane.
2105 Default value for @option{luma_power} is 2. If not specified,
2106 @option{chroma_power} and @option{alpha_power} default to the
2107 corresponding value set for @option{luma_power}.
2109 A value of 0 will disable the effect.
2112 @subsection Examples
2116 Apply a boxblur filter with luma, chroma, and alpha radius
2119 boxblur=luma_radius=2:luma_power=1
2124 Set luma radius to 2, alpha and chroma radius to 0:
2126 boxblur=2:1:cr=0:ar=0
2130 Set luma and chroma radius to a fraction of the video dimension:
2132 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2136 @section colormatrix
2138 Convert color matrix.
2140 The filter accepts the following options:
2145 Specify the source and destination color matrix. Both values must be
2148 The accepted values are:
2164 For example to convert from BT.601 to SMPTE-240M, use the command:
2166 colormatrix=bt601:smpte240m
2171 Copy the input source unchanged to the output. Mainly useful for
2176 Crop the input video to given dimensions.
2178 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2179 separated by ':'. If the key of the first options is omitted, the
2180 arguments are interpreted according to the syntax
2181 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2183 A description of the accepted options follows:
2186 Width of the output video. It defaults to @code{iw}.
2187 This expression is evaluated only once during the filter
2191 Height of the output video. It defaults to @code{ih}.
2192 This expression is evaluated only once during the filter
2196 Horizontal position, in the input video, of the left edge of the output video.
2197 It defaults to @code{(in_w-out_w)/2}.
2198 This expression is evaluated per-frame.
2201 Vertical position, in the input video, of the top edge of the output video.
2202 It defaults to @code{(in_h-out_h)/2}.
2203 This expression is evaluated per-frame.
2206 If set to 1 will force the output display aspect ratio
2207 to be the same of the input, by changing the output sample aspect
2208 ratio. It defaults to 0.
2211 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2212 expressions containing the following constants:
2216 the computed values for @var{x} and @var{y}. They are evaluated for
2220 the input width and height
2223 same as @var{in_w} and @var{in_h}
2226 the output (cropped) width and height
2229 same as @var{out_w} and @var{out_h}
2232 same as @var{iw} / @var{ih}
2235 input sample aspect ratio
2238 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2241 horizontal and vertical chroma subsample values. For example for the
2242 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2245 the number of input frame, starting from 0
2248 timestamp expressed in seconds, NAN if the input timestamp is unknown
2252 The expression for @var{out_w} may depend on the value of @var{out_h},
2253 and the expression for @var{out_h} may depend on @var{out_w}, but they
2254 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2255 evaluated after @var{out_w} and @var{out_h}.
2257 The @var{x} and @var{y} parameters specify the expressions for the
2258 position of the top-left corner of the output (non-cropped) area. They
2259 are evaluated for each frame. If the evaluated value is not valid, it
2260 is approximated to the nearest valid value.
2262 The expression for @var{x} may depend on @var{y}, and the expression
2263 for @var{y} may depend on @var{x}.
2265 @subsection Examples
2269 Crop area with size 100x100 at position (12,34).
2274 Using named options, the example above becomes:
2276 crop=w=100:h=100:x=12:y=34
2280 Crop the central input area with size 100x100:
2286 Crop the central input area with size 2/3 of the input video:
2288 crop=2/3*in_w:2/3*in_h
2292 Crop the input video central square:
2299 Delimit the rectangle with the top-left corner placed at position
2300 100:100 and the right-bottom corner corresponding to the right-bottom
2301 corner of the input image:
2303 crop=in_w-100:in_h-100:100:100
2307 Crop 10 pixels from the left and right borders, and 20 pixels from
2308 the top and bottom borders
2310 crop=in_w-2*10:in_h-2*20
2314 Keep only the bottom right quarter of the input image:
2316 crop=in_w/2:in_h/2:in_w/2:in_h/2
2320 Crop height for getting Greek harmony:
2322 crop=in_w:1/PHI*in_w
2326 Appply trembling effect:
2328 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)
2332 Apply erratic camera effect depending on timestamp:
2334 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)"
2338 Set x depending on the value of y:
2340 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2346 Auto-detect crop size.
2348 Calculate necessary cropping parameters and prints the recommended
2349 parameters through the logging system. The detected dimensions
2350 correspond to the non-black area of the input video.
2352 The filter accepts parameters as a list of @var{key}=@var{value}
2353 pairs, separated by ":". If the key of the first options is omitted,
2354 the arguments are interpreted according to the syntax
2355 [@option{limit}[:@option{round}[:@option{reset}]]].
2357 A description of the accepted options follows.
2362 Set higher black value threshold, which can be optionally specified
2363 from nothing (0) to everything (255). An intensity value greater
2364 to the set value is considered non-black. Default value is 24.
2367 Set the value for which the width/height should be divisible by. The
2368 offset is automatically adjusted to center the video. Use 2 to get
2369 only even dimensions (needed for 4:2:2 video). 16 is best when
2370 encoding to most video codecs. Default value is 16.
2373 Set the counter that determines after how many frames cropdetect will
2374 reset the previously detected largest video area and start over to
2375 detect the current optimal crop area. Default value is 0.
2377 This can be useful when channel logos distort the video area. 0
2378 indicates never reset and return the largest area encountered during
2384 Apply color adjustments using curves.
2386 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2387 component (red, green and blue) has its values defined by @var{N} key points
2388 tied from each other using a smooth curve. The x-axis represents the pixel
2389 values from the input frame, and the y-axis the new pixel values to be set for
2392 By default, a component curve is defined by the two points @var{(0;0)} and
2393 @var{(1;1)}. This creates a straight line where each original pixel value is
2394 "adjusted" to its own value, which means no change to the image.
2396 The filter allows you to redefine these two points and add some more. A new
2397 curve (using a natural cubic spline interpolation) will be define to pass
2398 smoothly through all these new coordinates. The new defined points needs to be
2399 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2400 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2401 the vector spaces, the values will be clipped accordingly.
2403 If there is no key point defined in @code{x=0}, the filter will automatically
2404 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2405 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2407 The filter accepts the following options:
2411 Select one of the available color presets. This option can be used in addition
2412 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2413 options takes priority on the preset values.
2414 Available presets are:
2417 @item color_negative
2420 @item increase_contrast
2422 @item linear_contrast
2423 @item medium_contrast
2425 @item strong_contrast
2428 Default is @code{none}.
2430 Set the key points for the red component.
2432 Set the key points for the green component.
2434 Set the key points for the blue component.
2436 Set the key points for all components.
2437 Can be used in addition to the other key points component
2438 options. In this case, the unset component(s) will fallback on this
2439 @option{all} setting.
2442 To avoid some filtergraph syntax conflicts, each key points list need to be
2443 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2445 @subsection Examples
2449 Increase slightly the middle level of blue:
2451 curves=blue='0.5/0.58'
2457 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2459 Here we obtain the following coordinates for each components:
2462 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2464 @code{(0;0) (0.50;0.48) (1;1)}
2466 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2470 The previous example can also be achieved with the associated built-in preset:
2472 curves=preset=vintage
2484 Drop frames that do not differ greatly from the previous frame in
2485 order to reduce frame rate.
2487 The main use of this filter is for very-low-bitrate encoding
2488 (e.g. streaming over dialup modem), but it could in theory be used for
2489 fixing movies that were inverse-telecined incorrectly.
2491 A description of the accepted options follows.
2495 Set the maximum number of consecutive frames which can be dropped (if
2496 positive), or the minimum interval between dropped frames (if
2497 negative). If the value is 0, the frame is dropped unregarding the
2498 number of previous sequentially dropped frames.
2505 Set the dropping threshold values.
2507 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2508 represent actual pixel value differences, so a threshold of 64
2509 corresponds to 1 unit of difference for each pixel, or the same spread
2510 out differently over the block.
2512 A frame is a candidate for dropping if no 8x8 blocks differ by more
2513 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2514 meaning the whole image) differ by more than a threshold of @option{lo}.
2516 Default value for @option{hi} is 64*12, default value for @option{lo} is
2517 64*5, and default value for @option{frac} is 0.33.
2522 Suppress a TV station logo by a simple interpolation of the surrounding
2523 pixels. Just set a rectangle covering the logo and watch it disappear
2524 (and sometimes something even uglier appear - your mileage may vary).
2526 This filter accepts the following options:
2530 Specify the top left corner coordinates of the logo. They must be
2534 Specify the width and height of the logo to clear. They must be
2538 Specify the thickness of the fuzzy edge of the rectangle (added to
2539 @var{w} and @var{h}). The default value is 4.
2542 When set to 1, a green rectangle is drawn on the screen to simplify
2543 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2544 @var{band} is set to 4. The default value is 0.
2548 @subsection Examples
2552 Set a rectangle covering the area with top left corner coordinates 0,0
2553 and size 100x77, setting a band of size 10:
2555 delogo=x=0:y=0:w=100:h=77:band=10
2562 Attempt to fix small changes in horizontal and/or vertical shift. This
2563 filter helps remove camera shake from hand-holding a camera, bumping a
2564 tripod, moving on a vehicle, etc.
2566 The filter accepts the following options:
2574 Specify a rectangular area where to limit the search for motion
2576 If desired the search for motion vectors can be limited to a
2577 rectangular area of the frame defined by its top left corner, width
2578 and height. These parameters have the same meaning as the drawbox
2579 filter which can be used to visualise the position of the bounding
2582 This is useful when simultaneous movement of subjects within the frame
2583 might be confused for camera motion by the motion vector search.
2585 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2586 then the full frame is used. This allows later options to be set
2587 without specifying the bounding box for the motion vector search.
2589 Default - search the whole frame.
2593 Specify the maximum extent of movement in x and y directions in the
2594 range 0-64 pixels. Default 16.
2597 Specify how to generate pixels to fill blanks at the edge of the
2598 frame. Available values are:
2601 Fill zeroes at blank locations
2603 Original image at blank locations
2605 Extruded edge value at blank locations
2607 Mirrored edge at blank locations
2609 Default value is @samp{mirror}.
2612 Specify the blocksize to use for motion search. Range 4-128 pixels,
2616 Specify the contrast threshold for blocks. Only blocks with more than
2617 the specified contrast (difference between darkest and lightest
2618 pixels) will be considered. Range 1-255, default 125.
2621 Specify the search strategy. Available values are:
2624 Set exhaustive search
2626 Set less exhaustive search.
2628 Default value is @samp{exhaustive}.
2631 If set then a detailed log of the motion search is written to the
2635 If set to 1, specify using OpenCL capabilities, only available if
2636 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2642 Draw a colored box on the input image.
2644 This filter accepts the following options:
2648 Specify the top left corner coordinates of the box. Default to 0.
2652 Specify the width and height of the box, if 0 they are interpreted as
2653 the input width and height. Default to 0.
2656 Specify the color of the box to write, it can be the name of a color
2657 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2658 value @code{invert} is used, the box edge color is the same as the
2659 video with inverted luma.
2662 Set the thickness of the box edge. Default value is @code{4}.
2665 @subsection Examples
2669 Draw a black box around the edge of the input image:
2675 Draw a box with color red and an opacity of 50%:
2677 drawbox=10:20:200:60:red@@0.5
2680 The previous example can be specified as:
2682 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2686 Fill the box with pink color:
2688 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2695 Draw text string or text from specified file on top of video using the
2696 libfreetype library.
2698 To enable compilation of this filter you need to configure FFmpeg with
2699 @code{--enable-libfreetype}.
2703 The description of the accepted parameters follows.
2708 Used to draw a box around text using background color.
2709 Value should be either 1 (enable) or 0 (disable).
2710 The default value of @var{box} is 0.
2713 The color to be used for drawing box around text.
2714 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2715 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2716 The default value of @var{boxcolor} is "white".
2719 Set an expression which specifies if the text should be drawn. If the
2720 expression evaluates to 0, the text is not drawn. This is useful for
2721 specifying that the text should be drawn only when specific conditions
2724 Default value is "1".
2726 See below for the list of accepted constants and functions.
2729 Select how the @var{text} is expanded. Can be either @code{none},
2730 @code{strftime} (deprecated) or
2731 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2735 If true, check and fix text coords to avoid clipping.
2738 The color to be used for drawing fonts.
2739 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2740 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2741 The default value of @var{fontcolor} is "black".
2744 The font file to be used for drawing text. Path must be included.
2745 This parameter is mandatory.
2748 The font size to be used for drawing text.
2749 The default value of @var{fontsize} is 16.
2752 Flags to be used for loading the fonts.
2754 The flags map the corresponding flags supported by libfreetype, and are
2755 a combination of the following values:
2762 @item vertical_layout
2763 @item force_autohint
2766 @item ignore_global_advance_width
2768 @item ignore_transform
2775 Default value is "render".
2777 For more information consult the documentation for the FT_LOAD_*
2781 The color to be used for drawing a shadow behind the drawn text. It
2782 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2783 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2784 The default value of @var{shadowcolor} is "black".
2786 @item shadowx, shadowy
2787 The x and y offsets for the text shadow position with respect to the
2788 position of the text. They can be either positive or negative
2789 values. Default value for both is "0".
2792 The size in number of spaces to use for rendering the tab.
2796 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2797 format. It can be used with or without text parameter. @var{timecode_rate}
2798 option must be specified.
2800 @item timecode_rate, rate, r
2801 Set the timecode frame rate (timecode only).
2804 The text string to be drawn. The text must be a sequence of UTF-8
2806 This parameter is mandatory if no file is specified with the parameter
2810 A text file containing text to be drawn. The text must be a sequence
2811 of UTF-8 encoded characters.
2813 This parameter is mandatory if no text string is specified with the
2814 parameter @var{text}.
2816 If both @var{text} and @var{textfile} are specified, an error is thrown.
2819 If set to 1, the @var{textfile} will be reloaded before each frame.
2820 Be sure to update it atomically, or it may be read partially, or even fail.
2823 The expressions which specify the offsets where text will be drawn
2824 within the video frame. They are relative to the top/left border of the
2827 The default value of @var{x} and @var{y} is "0".
2829 See below for the list of accepted constants and functions.
2832 The parameters for @var{x} and @var{y} are expressions containing the
2833 following constants and functions:
2837 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2840 horizontal and vertical chroma subsample values. For example for the
2841 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2844 the height of each text line
2852 @item max_glyph_a, ascent
2853 the maximum distance from the baseline to the highest/upper grid
2854 coordinate used to place a glyph outline point, for all the rendered
2856 It is a positive value, due to the grid's orientation with the Y axis
2859 @item max_glyph_d, descent
2860 the maximum distance from the baseline to the lowest grid coordinate
2861 used to place a glyph outline point, for all the rendered glyphs.
2862 This is a negative value, due to the grid's orientation, with the Y axis
2866 maximum glyph height, that is the maximum height for all the glyphs
2867 contained in the rendered text, it is equivalent to @var{ascent} -
2871 maximum glyph width, that is the maximum width for all the glyphs
2872 contained in the rendered text
2875 the number of input frame, starting from 0
2877 @item rand(min, max)
2878 return a random number included between @var{min} and @var{max}
2881 input sample aspect ratio
2884 timestamp expressed in seconds, NAN if the input timestamp is unknown
2887 the height of the rendered text
2890 the width of the rendered text
2893 the x and y offset coordinates where the text is drawn.
2895 These parameters allow the @var{x} and @var{y} expressions to refer
2896 each other, so you can for example specify @code{y=x/dar}.
2899 If libavfilter was built with @code{--enable-fontconfig}, then
2900 @option{fontfile} can be a fontconfig pattern or omitted.
2902 @anchor{drawtext_expansion}
2903 @subsection Text expansion
2905 If @option{expansion} is set to @code{strftime},
2906 the filter recognizes strftime() sequences in the provided text and
2907 expands them accordingly. Check the documentation of strftime(). This
2908 feature is deprecated.
2910 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2912 If @option{expansion} is set to @code{normal} (which is the default),
2913 the following expansion mechanism is used.
2915 The backslash character '\', followed by any character, always expands to
2916 the second character.
2918 Sequence of the form @code{%@{...@}} are expanded. The text between the
2919 braces is a function name, possibly followed by arguments separated by ':'.
2920 If the arguments contain special characters or delimiters (':' or '@}'),
2921 they should be escaped.
2923 Note that they probably must also be escaped as the value for the
2924 @option{text} option in the filter argument string and as the filter
2925 argument in the filtergraph description, and possibly also for the shell,
2926 that makes up to four levels of escaping; using a text file avoids these
2929 The following functions are available:
2934 The expression evaluation result.
2936 It must take one argument specifying the expression to be evaluated,
2937 which accepts the same constants and functions as the @var{x} and
2938 @var{y} values. Note that not all constants should be used, for
2939 example the text size is not known when evaluating the expression, so
2940 the constants @var{text_w} and @var{text_h} will have an undefined
2944 The time at which the filter is running, expressed in UTC.
2945 It can accept an argument: a strftime() format string.
2948 The time at which the filter is running, expressed in the local time zone.
2949 It can accept an argument: a strftime() format string.
2952 The frame number, starting from 0.
2955 The timestamp of the current frame, in seconds, with microsecond accuracy.
2959 @subsection Examples
2963 Draw "Test Text" with font FreeSerif, using the default values for the
2964 optional parameters.
2967 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2971 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2972 and y=50 (counting from the top-left corner of the screen), text is
2973 yellow with a red box around it. Both the text and the box have an
2977 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2978 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2981 Note that the double quotes are not necessary if spaces are not used
2982 within the parameter list.
2985 Show the text at the center of the video frame:
2987 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2991 Show a text line sliding from right to left in the last row of the video
2992 frame. The file @file{LONG_LINE} is assumed to contain a single line
2995 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2999 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3001 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3005 Draw a single green letter "g", at the center of the input video.
3006 The glyph baseline is placed at half screen height.
3008 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3012 Show text for 1 second every 3 seconds:
3014 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3018 Use fontconfig to set the font. Note that the colons need to be escaped.
3020 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3024 Print the date of a real-time encoding (see strftime(3)):
3026 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3031 For more information about libfreetype, check:
3032 @url{http://www.freetype.org/}.
3034 For more information about fontconfig, check:
3035 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3039 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3041 The filter accepts the following options:
3045 Set low and high threshold values used by the Canny thresholding
3048 The high threshold selects the "strong" edge pixels, which are then
3049 connected through 8-connectivity with the "weak" edge pixels selected
3050 by the low threshold.
3052 @var{low} and @var{high} threshold values must be choosen in the range
3053 [0,1], and @var{low} should be lesser or equal to @var{high}.
3055 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3061 edgedetect=low=0.1:high=0.4
3066 Apply fade-in/out effect to input video.
3068 This filter accepts the following options:
3072 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3074 Default is @code{in}.
3076 @item start_frame, s
3077 Specify the number of the start frame for starting to apply the fade
3078 effect. Default is 0.
3081 The number of frames for which the fade effect has to last. At the end of the
3082 fade-in effect the output video will have the same intensity as the input video,
3083 at the end of the fade-out transition the output video will be completely black.
3087 If set to 1, fade only alpha channel, if one exists on the input.
3091 @subsection Examples
3095 Fade in first 30 frames of video:
3100 The command above is equivalent to:
3106 Fade out last 45 frames of a 200-frame video:
3109 fade=type=out:start_frame=155:nb_frames=45
3113 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3115 fade=in:0:25, fade=out:975:25
3119 Make first 5 frames black, then fade in from frame 5-24:
3125 Fade in alpha over first 25 frames of video:
3127 fade=in:0:25:alpha=1
3133 Extract a single field from an interlaced image using stride
3134 arithmetic to avoid wasting CPU time. The output frames are marked as
3137 The filter accepts the following options:
3141 Specify whether to extract the top (if the value is @code{0} or
3142 @code{top}) or the bottom field (if the value is @code{1} or
3148 Transform the field order of the input video.
3150 This filter accepts the following options:
3155 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3156 for bottom field first.
3159 Default value is @samp{tff}.
3161 Transformation is achieved by shifting the picture content up or down
3162 by one line, and filling the remaining line with appropriate picture content.
3163 This method is consistent with most broadcast field order converters.
3165 If the input video is not flagged as being interlaced, or it is already
3166 flagged as being of the required output field order then this filter does
3167 not alter the incoming video.
3169 This filter is very useful when converting to or from PAL DV material,
3170 which is bottom field first.
3174 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3179 Buffer input images and send them when they are requested.
3181 This filter is mainly useful when auto-inserted by the libavfilter
3184 The filter does not take parameters.
3189 Convert the input video to one of the specified pixel formats.
3190 Libavfilter will try to pick one that is supported for the input to
3193 This filter accepts the following parameters:
3197 A '|'-separated list of pixel format names, for example
3198 "pix_fmts=yuv420p|monow|rgb24".
3202 @subsection Examples
3206 Convert the input video to the format @var{yuv420p}
3208 format=pix_fmts=yuv420p
3211 Convert the input video to any of the formats in the list
3213 format=pix_fmts=yuv420p|yuv444p|yuv410p
3219 Convert the video to specified constant frame rate by duplicating or dropping
3220 frames as necessary.
3222 This filter accepts the following named parameters:
3226 Desired output frame rate. The default is @code{25}.
3231 Possible values are:
3234 zero round towards 0
3238 round towards -infinity
3240 round towards +infinity
3244 The default is @code{near}.
3248 Alternatively, the options can be specified as a flat string:
3249 @var{fps}[:@var{round}].
3251 See also the @ref{setpts} filter.
3255 Select one frame every N-th frame.
3257 This filter accepts the following option:
3260 Select frame after every @code{step} frames.
3261 Allowed values are positive integers higher than 0. Default value is @code{1}.
3267 Apply a frei0r effect to the input video.
3269 To enable compilation of this filter you need to install the frei0r
3270 header and configure FFmpeg with @code{--enable-frei0r}.
3272 This filter accepts the following options:
3277 The name to the frei0r effect to load. If the environment variable
3278 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3279 directories specified by the colon separated list in @env{FREIOR_PATH},
3280 otherwise in the standard frei0r paths, which are in this order:
3281 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3282 @file{/usr/lib/frei0r-1/}.
3285 A '|'-separated list of parameters to pass to the frei0r effect.
3289 A frei0r effect parameter can be a boolean (whose values are specified
3290 with "y" and "n"), a double, a color (specified by the syntax
3291 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3292 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3293 description), a position (specified by the syntax @var{X}/@var{Y},
3294 @var{X} and @var{Y} being float numbers) and a string.
3296 The number and kind of parameters depend on the loaded effect. If an
3297 effect parameter is not specified the default value is set.
3299 @subsection Examples
3303 Apply the distort0r effect, set the first two double parameters:
3305 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3309 Apply the colordistance effect, take a color as first parameter:
3311 frei0r=colordistance:0.2/0.3/0.4
3312 frei0r=colordistance:violet
3313 frei0r=colordistance:0x112233
3317 Apply the perspective effect, specify the top left and top right image
3320 frei0r=perspective:0.2/0.2|0.8/0.2
3324 For more information see:
3325 @url{http://frei0r.dyne.org}
3329 The filter accepts the following options:
3333 the luminance expression
3335 the chrominance blue expression
3337 the chrominance red expression
3339 the alpha expression
3342 If one of the chrominance expression is not defined, it falls back on the other
3343 one. If no alpha expression is specified it will evaluate to opaque value.
3344 If none of chrominance expressions are
3345 specified, they will evaluate the luminance expression.
3347 The expressions can use the following variables and functions:
3351 The sequential number of the filtered frame, starting from @code{0}.
3355 The coordinates of the current sample.
3359 The width and height of the image.
3363 Width and height scale depending on the currently filtered plane. It is the
3364 ratio between the corresponding luma plane number of pixels and the current
3365 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3366 @code{0.5,0.5} for chroma planes.
3369 Time of the current frame, expressed in seconds.
3372 Return the value of the pixel at location (@var{x},@var{y}) of the current
3376 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3380 Return the value of the pixel at location (@var{x},@var{y}) of the
3381 blue-difference chroma plane. Returns 0 if there is no such plane.
3384 Return the value of the pixel at location (@var{x},@var{y}) of the
3385 red-difference chroma plane. Returns 0 if there is no such plane.
3388 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3389 plane. Returns 0 if there is no such plane.
3392 For functions, if @var{x} and @var{y} are outside the area, the value will be
3393 automatically clipped to the closer edge.
3395 @subsection Examples
3399 Flip the image horizontally:
3405 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3406 wavelength of 100 pixels:
3408 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3412 Generate a fancy enigmatic moving light:
3414 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
3420 Fix the banding artifacts that are sometimes introduced into nearly flat
3421 regions by truncation to 8bit color depth.
3422 Interpolate the gradients that should go where the bands are, and
3425 This filter is designed for playback only. Do not use it prior to
3426 lossy compression, because compression tends to lose the dither and
3427 bring back the bands.
3429 This filter accepts the following options:
3434 The maximum amount by which the filter will change any one pixel. Also the
3435 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3436 64, default value is 1.2, out-of-range values will be clipped to the valid
3440 The neighborhood to fit the gradient to. A larger radius makes for smoother
3441 gradients, but also prevents the filter from modifying the pixels near detailed
3442 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3443 will be clipped to the valid range.
3447 Alternatively, the options can be specified as a flat string:
3448 @var{strength}[:@var{radius}]
3450 @subsection Examples
3454 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3460 Specify radius, omitting the strength (which will fall-back to the default
3470 Flip the input video horizontally.
3472 For example to horizontally flip the input video with @command{ffmpeg}:
3474 ffmpeg -i in.avi -vf "hflip" out.avi
3478 This filter applies a global color histogram equalization on a
3481 It can be used to correct video that has a compressed range of pixel
3482 intensities. The filter redistributes the pixel intensities to
3483 equalize their distribution across the intensity range. It may be
3484 viewed as an "automatically adjusting contrast filter". This filter is
3485 useful only for correcting degraded or poorly captured source
3488 The filter accepts the following options:
3492 Determine the amount of equalization to be applied. As the strength
3493 is reduced, the distribution of pixel intensities more-and-more
3494 approaches that of the input frame. The value must be a float number
3495 in the range [0,1] and defaults to 0.200.
3498 Set the maximum intensity that can generated and scale the output
3499 values appropriately. The strength should be set as desired and then
3500 the intensity can be limited if needed to avoid washing-out. The value
3501 must be a float number in the range [0,1] and defaults to 0.210.
3504 Set the antibanding level. If enabled the filter will randomly vary
3505 the luminance of output pixels by a small amount to avoid banding of
3506 the histogram. Possible values are @code{none}, @code{weak} or
3507 @code{strong}. It defaults to @code{none}.
3512 Compute and draw a color distribution histogram for the input video.
3514 The computed histogram is a representation of distribution of color components
3517 The filter accepts the following options:
3523 It accepts the following values:
3526 standard histogram that display color components distribution in an image.
3527 Displays color graph for each color component. Shows distribution
3528 of the Y, U, V, A or G, B, R components, depending on input format,
3529 in current frame. Bellow each graph is color component scale meter.
3532 chroma values in vectorscope, if brighter more such chroma values are
3533 distributed in an image.
3534 Displays chroma values (U/V color placement) in two dimensional graph
3535 (which is called a vectorscope). It can be used to read of the hue and
3536 saturation of the current frame. At a same time it is a histogram.
3537 The whiter a pixel in the vectorscope, the more pixels of the input frame
3538 correspond to that pixel (that is the more pixels have this chroma value).
3539 The V component is displayed on the horizontal (X) axis, with the leftmost
3540 side being V = 0 and the rightmost side being V = 255.
3541 The U component is displayed on the vertical (Y) axis, with the top
3542 representing U = 0 and the bottom representing U = 255.
3544 The position of a white pixel in the graph corresponds to the chroma value
3545 of a pixel of the input clip. So the graph can be used to read of the
3546 hue (color flavor) and the saturation (the dominance of the hue in the color).
3547 As the hue of a color changes, it moves around the square. At the center of
3548 the square, the saturation is zero, which means that the corresponding pixel
3549 has no color. If you increase the amount of a specific color, while leaving
3550 the other colors unchanged, the saturation increases, and you move towards
3551 the edge of the square.
3554 chroma values in vectorscope, similar as @code{color} but actual chroma values
3558 per row/column color component graph. In row mode graph in the left side represents
3559 color component value 0 and right side represents value = 255. In column mode top
3560 side represents color component value = 0 and bottom side represents value = 255.
3562 Default value is @code{levels}.
3565 Set height of level in @code{levels}. Default value is @code{200}.
3566 Allowed range is [50, 2048].
3569 Set height of color scale in @code{levels}. Default value is @code{12}.
3570 Allowed range is [0, 40].
3573 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3574 of same luminance values across input rows/columns are distributed.
3575 Default value is @code{10}. Allowed range is [1, 255].
3578 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3579 Default is @code{row}.
3582 Set display mode for @code{waveform} and @code{levels}.
3583 It accepts the following values:
3586 Display separate graph for the color components side by side in
3587 @code{row} waveform mode or one below other in @code{column} waveform mode
3588 for @code{waveform} histogram mode. For @code{levels} histogram mode
3589 per color component graphs are placed one bellow other.
3591 This display mode in @code{waveform} histogram mode makes it easy to spot
3592 color casts in the highlights and shadows of an image, by comparing the
3593 contours of the top and the bottom of each waveform.
3594 Since whites, grays, and blacks are characterized by
3595 exactly equal amounts of red, green, and blue, neutral areas of the
3596 picture should display three waveforms of roughly equal width/height.
3597 If not, the correction is easy to make by making adjustments to level the
3601 Presents information that's identical to that in the @code{parade}, except
3602 that the graphs representing color components are superimposed directly
3605 This display mode in @code{waveform} histogram mode can make it easier to spot
3606 the relative differences or similarities in overlapping areas of the color
3607 components that are supposed to be identical, such as neutral whites, grays,
3610 Default is @code{parade}.
3613 @subsection Examples
3618 Calculate and draw histogram:
3620 ffplay -i input -vf histogram
3627 High precision/quality 3d denoise filter. This filter aims to reduce
3628 image noise producing smooth images and making still images really
3629 still. It should enhance compressibility.
3631 It accepts the following optional parameters:
3635 a non-negative float number which specifies spatial luma strength,
3638 @item chroma_spatial
3639 a non-negative float number which specifies spatial chroma strength,
3640 defaults to 3.0*@var{luma_spatial}/4.0
3643 a float number which specifies luma temporal strength, defaults to
3644 6.0*@var{luma_spatial}/4.0
3647 a float number which specifies chroma temporal strength, defaults to
3648 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3653 Modify the hue and/or the saturation of the input.
3655 This filter accepts the following options:
3659 Specify the hue angle as a number of degrees. It accepts an expression,
3660 and defaults to "0".
3663 Specify the saturation in the [-10,10] range. It accepts a float number and
3667 Specify the hue angle as a number of radians. It accepts a float
3668 number or an expression, and defaults to "0".
3671 @option{h} and @option{H} are mutually exclusive, and can't be
3672 specified at the same time.
3674 The @option{h}, @option{H} and @option{s} option values are
3675 expressions containing the following constants:
3679 frame count of the input frame starting from 0
3682 presentation timestamp of the input frame expressed in time base units
3685 frame rate of the input video, NAN if the input frame rate is unknown
3688 timestamp expressed in seconds, NAN if the input timestamp is unknown
3691 time base of the input video
3694 @subsection Examples
3698 Set the hue to 90 degrees and the saturation to 1.0:
3704 Same command but expressing the hue in radians:
3710 Rotate hue and make the saturation swing between 0
3711 and 2 over a period of 1 second:
3713 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3717 Apply a 3 seconds saturation fade-in effect starting at 0:
3722 The general fade-in expression can be written as:
3724 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3728 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3730 hue="s=max(0\, min(1\, (8-t)/3))"
3733 The general fade-out expression can be written as:
3735 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3740 @subsection Commands
3742 This filter supports the following command:
3747 Modify the hue and/or the saturation of the input video.
3748 The command accepts the same options and syntax of the corresponding
3751 If the specified expression is not valid, it is kept at its current
3757 Detect video interlacing type.
3759 This filter tries to detect if the input is interlaced or progressive,
3760 top or bottom field first.
3762 The filter accepts the following options:
3766 Set interlacing threshold.
3768 Set progressive threshold.
3773 Deinterleave or interleave fields.
3775 This filter allows to process interlaced images fields without
3776 deinterlacing them. Deinterleaving splits the input frame into 2
3777 fields (so called half pictures). Odd lines are moved to the top
3778 half of the output image, even lines to the bottom half.
3779 You can process (filter) them independently and then re-interleave them.
3781 The filter accepts the following options:
3785 @item chroma_mode, s
3787 Available values for @var{luma_mode}, @var{chroma_mode} and
3788 @var{alpha_mode} are:
3794 @item deinterleave, d
3795 Deinterleave fields, placing one above the other.
3798 Interleave fields. Reverse the effect of deinterleaving.
3800 Default value is @code{none}.
3803 @item chroma_swap, cs
3804 @item alpha_swap, as
3805 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3810 Deinterlace input video by applying Donald Graft's adaptive kernel
3811 deinterling. Work on interlaced parts of a video to produce
3814 The description of the accepted parameters follows.
3818 Set the threshold which affects the filter's tolerance when
3819 determining if a pixel line must be processed. It must be an integer
3820 in the range [0,255] and defaults to 10. A value of 0 will result in
3821 applying the process on every pixels.
3824 Paint pixels exceeding the threshold value to white if set to 1.
3828 Set the fields order. Swap fields if set to 1, leave fields alone if
3832 Enable additional sharpening if set to 1. Default is 0.
3835 Enable twoway sharpening if set to 1. Default is 0.
3838 @subsection Examples
3842 Apply default values:
3844 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3848 Enable additional sharpening:
3854 Paint processed pixels in white:
3860 @section lut, lutrgb, lutyuv
3862 Compute a look-up table for binding each pixel component input value
3863 to an output value, and apply it to input video.
3865 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3866 to an RGB input video.
3868 These filters accept the following options:
3871 set first pixel component expression
3873 set second pixel component expression
3875 set third pixel component expression
3877 set fourth pixel component expression, corresponds to the alpha component
3880 set red component expression
3882 set green component expression
3884 set blue component expression
3886 alpha component expression
3889 set Y/luminance component expression
3891 set U/Cb component expression
3893 set V/Cr component expression
3896 Each of them specifies the expression to use for computing the lookup table for
3897 the corresponding pixel component values.
3899 The exact component associated to each of the @var{c*} options depends on the
3902 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3903 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3905 The expressions can contain the following constants and functions:
3909 the input width and height
3912 input value for the pixel component
3915 the input value clipped in the @var{minval}-@var{maxval} range
3918 maximum value for the pixel component
3921 minimum value for the pixel component
3924 the negated value for the pixel component value clipped in the
3925 @var{minval}-@var{maxval} range , it corresponds to the expression
3926 "maxval-clipval+minval"
3929 the computed value in @var{val} clipped in the
3930 @var{minval}-@var{maxval} range
3932 @item gammaval(gamma)
3933 the computed gamma correction value of the pixel component value
3934 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3936 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3940 All expressions default to "val".
3942 @subsection Examples
3948 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3949 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3952 The above is the same as:
3954 lutrgb="r=negval:g=negval:b=negval"
3955 lutyuv="y=negval:u=negval:v=negval"
3965 Remove chroma components, turns the video into a graytone image:
3967 lutyuv="u=128:v=128"
3971 Apply a luma burning effect:
3977 Remove green and blue components:
3983 Set a constant alpha channel value on input:
3985 format=rgba,lutrgb=a="maxval-minval/2"
3989 Correct luminance gamma by a 0.5 factor:
3991 lutyuv=y=gammaval(0.5)
3995 Discard least significant bits of luma:
3997 lutyuv=y='bitand(val, 128+64+32)'
4003 Apply an MPlayer filter to the input video.
4005 This filter provides a wrapper around most of the filters of
4008 This wrapper is considered experimental. Some of the wrapped filters
4009 may not work properly and we may drop support for them, as they will
4010 be implemented natively into FFmpeg. Thus you should avoid
4011 depending on them when writing portable scripts.
4013 The filters accepts the parameters:
4014 @var{filter_name}[:=]@var{filter_params}
4016 @var{filter_name} is the name of a supported MPlayer filter,
4017 @var{filter_params} is a string containing the parameters accepted by
4020 The list of the currently supported filters follows:
4047 The parameter syntax and behavior for the listed filters are the same
4048 of the corresponding MPlayer filters. For detailed instructions check
4049 the "VIDEO FILTERS" section in the MPlayer manual.
4051 @subsection Examples
4055 Adjust gamma, brightness, contrast:
4061 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4067 This filter accepts an integer in input, if non-zero it negates the
4068 alpha component (if available). The default value in input is 0.
4072 Force libavfilter not to use any of the specified pixel formats for the
4073 input to the next filter.
4075 This filter accepts the following parameters:
4079 A '|'-separated list of pixel format names, for example
4080 "pix_fmts=yuv420p|monow|rgb24".
4084 @subsection Examples
4088 Force libavfilter to use a format different from @var{yuv420p} for the
4089 input to the vflip filter:
4091 noformat=pix_fmts=yuv420p,vflip
4095 Convert the input video to any of the formats not contained in the list:
4097 noformat=yuv420p|yuv444p|yuv410p
4103 Add noise on video input frame.
4105 The filter accepts the following options:
4113 Set noise seed for specific pixel component or all pixel components in case
4114 of @var{all_seed}. Default value is @code{123457}.
4116 @item all_strength, alls
4117 @item c0_strength, c0s
4118 @item c1_strength, c1s
4119 @item c2_strength, c2s
4120 @item c3_strength, c3s
4121 Set noise strength for specific pixel component or all pixel components in case
4122 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4124 @item all_flags, allf
4129 Set pixel component flags or set flags for all components if @var{all_flags}.
4130 Available values for component flags are:
4133 averaged temporal noise (smoother)
4135 mix random noise with a (semi)regular pattern
4137 higher quality (slightly better looking, slightly slower)
4139 temporal noise (noise pattern changes between frames)
4141 uniform noise (gaussian otherwise)
4145 @subsection Examples
4147 Add temporal and uniform noise to input video:
4149 noise=alls=20:allf=t+u
4154 Pass the video source unchanged to the output.
4158 Apply video transform using libopencv.
4160 To enable this filter install libopencv library and headers and
4161 configure FFmpeg with @code{--enable-libopencv}.
4163 This filter accepts the following parameters:
4168 The name of the libopencv filter to apply.
4171 The parameters to pass to the libopencv filter. If not specified the default
4176 Refer to the official libopencv documentation for more precise
4178 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4180 Follows the list of supported libopencv filters.
4185 Dilate an image by using a specific structuring element.
4186 This filter corresponds to the libopencv function @code{cvDilate}.
4188 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4190 @var{struct_el} represents a structuring element, and has the syntax:
4191 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4193 @var{cols} and @var{rows} represent the number of columns and rows of
4194 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4195 point, and @var{shape} the shape for the structuring element, and
4196 can be one of the values "rect", "cross", "ellipse", "custom".
4198 If the value for @var{shape} is "custom", it must be followed by a
4199 string of the form "=@var{filename}". The file with name
4200 @var{filename} is assumed to represent a binary image, with each
4201 printable character corresponding to a bright pixel. When a custom
4202 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4203 or columns and rows of the read file are assumed instead.
4205 The default value for @var{struct_el} is "3x3+0x0/rect".
4207 @var{nb_iterations} specifies the number of times the transform is
4208 applied to the image, and defaults to 1.
4210 Follow some example:
4212 # use the default values
4215 # dilate using a structuring element with a 5x5 cross, iterate two times
4216 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4218 # read the shape from the file diamond.shape, iterate two times
4219 # the file diamond.shape may contain a pattern of characters like this:
4225 # the specified cols and rows are ignored (but not the anchor point coordinates)
4226 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4231 Erode an image by using a specific structuring element.
4232 This filter corresponds to the libopencv function @code{cvErode}.
4234 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4235 with the same syntax and semantics as the @ref{dilate} filter.
4239 Smooth the input video.
4241 The filter takes the following parameters:
4242 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4244 @var{type} is the type of smooth filter to apply, and can be one of
4245 the following values: "blur", "blur_no_scale", "median", "gaussian",
4246 "bilateral". The default value is "gaussian".
4248 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4249 parameters whose meanings depend on smooth type. @var{param1} and
4250 @var{param2} accept integer positive values or 0, @var{param3} and
4251 @var{param4} accept float values.
4253 The default value for @var{param1} is 3, the default value for the
4254 other parameters is 0.
4256 These parameters correspond to the parameters assigned to the
4257 libopencv function @code{cvSmooth}.
4262 Overlay one video on top of another.
4264 It takes two inputs and one output, the first input is the "main"
4265 video on which the second input is overlayed.
4267 This filter accepts the following parameters:
4269 A description of the accepted options follows.
4274 Set the expression for the x and y coordinates of the overlayed video
4275 on the main video. Default value is "0" for both expressions. In case
4276 the expression is invalid, it is set to a huge value (meaning that the
4277 overlay will not be displayed within the output visible area).
4280 Set the expression which enables the overlay. If the evaluation is
4281 different from 0, the overlay is displayed on top of the input
4282 frame. By default it is "1".
4285 Set when the expressions for @option{x}, @option{y}, and
4286 @option{enable} are evaluated.
4288 It accepts the following values:
4291 only evaluate expressions once during the filter initialization or
4292 when a command is processed
4295 evaluate expressions for each incoming frame
4298 Default value is @samp{frame}.
4301 If set to 1, force the output to terminate when the shortest input
4302 terminates. Default value is 0.
4305 Set the format for the output video.
4307 It accepts the following values:
4319 Default value is @samp{yuv420}.
4321 @item rgb @emph{(deprecated)}
4322 If set to 1, force the filter to accept inputs in the RGB
4323 color space. Default value is 0. This option is deprecated, use
4324 @option{format} instead.
4327 The @option{x}, @option{y}, and @option{enable} expressions can
4328 contain the following parameters.
4333 main input width and height
4337 overlay input width and height
4341 the computed values for @var{x} and @var{y}. They are evaluated for
4346 horizontal and vertical chroma subsample values of the output
4347 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4351 the number of input frame, starting from 0
4354 the position in the file of the input frame, NAN if unknown
4357 timestamp expressed in seconds, NAN if the input timestamp is unknown
4360 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4361 when evaluation is done @emph{per frame}, and will evaluate to NAN
4362 when @option{eval} is set to @samp{init}.
4364 Be aware that frames are taken from each input video in timestamp
4365 order, hence, if their initial timestamps differ, it is a a good idea
4366 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4367 have them begin in the same zero timestamp, as it does the example for
4368 the @var{movie} filter.
4370 You can chain together more overlays but you should test the
4371 efficiency of such approach.
4373 @subsection Commands
4375 This filter supports the following command:
4378 Set the @option{x} option expression.
4381 Set the @option{y} option expression.
4384 Set the @option{enable} option expression.
4387 @subsection Examples
4391 Draw the overlay at 10 pixels from the bottom right corner of the main
4394 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4397 Using named options the example above becomes:
4399 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4403 Insert a transparent PNG logo in the bottom left corner of the input,
4404 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4406 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4410 Insert 2 different transparent PNG logos (second logo on bottom
4411 right corner) using the @command{ffmpeg} tool:
4413 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
4417 Add a transparent color layer on top of the main video, @code{WxH}
4418 must specify the size of the main input to the overlay filter:
4420 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4424 Play an original video and a filtered version (here with the deshake
4425 filter) side by side using the @command{ffplay} tool:
4427 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4430 The above command is the same as:
4432 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4436 Make a sliding overlay appearing from the left to the right top part of the
4437 screen starting since time 2:
4439 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4443 Compose output by putting two input videos side to side:
4445 ffmpeg -i left.avi -i right.avi -filter_complex "
4446 nullsrc=size=200x100 [background];
4447 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4448 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4449 [background][left] overlay=shortest=1 [background+left];
4450 [background+left][right] overlay=shortest=1:x=100 [left+right]
4455 Chain several overlays in cascade:
4457 nullsrc=s=200x200 [bg];
4458 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4459 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4460 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4461 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4462 [in3] null, [mid2] overlay=100:100 [out0]
4469 Add paddings to the input image, and place the original input at the
4470 given coordinates @var{x}, @var{y}.
4472 This filter accepts the following parameters:
4477 Specify an expression for the size of the output image with the
4478 paddings added. If the value for @var{width} or @var{height} is 0, the
4479 corresponding input size is used for the output.
4481 The @var{width} expression can reference the value set by the
4482 @var{height} expression, and vice versa.
4484 The default value of @var{width} and @var{height} is 0.
4488 Specify an expression for the offsets where to place the input image
4489 in the padded area with respect to the top/left border of the output
4492 The @var{x} expression can reference the value set by the @var{y}
4493 expression, and vice versa.
4495 The default value of @var{x} and @var{y} is 0.
4498 Specify the color of the padded area, it can be the name of a color
4499 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4501 The default value of @var{color} is "black".
4504 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4505 options are expressions containing the following constants:
4509 the input video width and height
4512 same as @var{in_w} and @var{in_h}
4515 the output width and height, that is the size of the padded area as
4516 specified by the @var{width} and @var{height} expressions
4519 same as @var{out_w} and @var{out_h}
4522 x and y offsets as specified by the @var{x} and @var{y}
4523 expressions, or NAN if not yet specified
4526 same as @var{iw} / @var{ih}
4529 input sample aspect ratio
4532 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4535 horizontal and vertical chroma subsample values. For example for the
4536 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4539 @subsection Examples
4543 Add paddings with color "violet" to the input video. Output video
4544 size is 640x480, the top-left corner of the input video is placed at
4547 pad=640:480:0:40:violet
4550 The example above is equivalent to the following command:
4552 pad=width=640:height=480:x=0:y=40:color=violet
4556 Pad the input to get an output with dimensions increased by 3/2,
4557 and put the input video at the center of the padded area:
4559 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4563 Pad the input to get a squared output with size equal to the maximum
4564 value between the input width and height, and put the input video at
4565 the center of the padded area:
4567 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4571 Pad the input to get a final w/h ratio of 16:9:
4573 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4577 In case of anamorphic video, in order to set the output display aspect
4578 correctly, it is necessary to use @var{sar} in the expression,
4579 according to the relation:
4581 (ih * X / ih) * sar = output_dar
4582 X = output_dar / sar
4585 Thus the previous example needs to be modified to:
4587 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4591 Double output size and put the input video in the bottom-right
4592 corner of the output padded area:
4594 pad="2*iw:2*ih:ow-iw:oh-ih"
4598 @section pixdesctest
4600 Pixel format descriptor test filter, mainly useful for internal
4601 testing. The output video should be equal to the input video.
4605 format=monow, pixdesctest
4608 can be used to test the monowhite pixel format descriptor definition.
4612 Enable the specified chain of postprocessing subfilters using libpostproc. This
4613 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4614 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4615 Each subfilter and some options have a short and a long name that can be used
4616 interchangeably, i.e. dr/dering are the same.
4618 The filters accept the following options:
4622 Set postprocessing subfilters string.
4625 All subfilters share common options to determine their scope:
4629 Honor the quality commands for this subfilter.
4632 Do chrominance filtering, too (default).
4635 Do luminance filtering only (no chrominance).
4638 Do chrominance filtering only (no luminance).
4641 These options can be appended after the subfilter name, separated by a '|'.
4643 Available subfilters are:
4646 @item hb/hdeblock[|difference[|flatness]]
4647 Horizontal deblocking filter
4650 Difference factor where higher values mean more deblocking (default: @code{32}).
4652 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4655 @item vb/vdeblock[|difference[|flatness]]
4656 Vertical deblocking filter
4659 Difference factor where higher values mean more deblocking (default: @code{32}).
4661 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4664 @item ha/hadeblock[|difference[|flatness]]
4665 Accurate horizontal deblocking filter
4668 Difference factor where higher values mean more deblocking (default: @code{32}).
4670 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4673 @item va/vadeblock[|difference[|flatness]]
4674 Accurate vertical deblocking filter
4677 Difference factor where higher values mean more deblocking (default: @code{32}).
4679 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4683 The horizontal and vertical deblocking filters share the difference and
4684 flatness values so you cannot set different horizontal and vertical
4689 Experimental horizontal deblocking filter
4692 Experimental vertical deblocking filter
4697 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4700 larger -> stronger filtering
4702 larger -> stronger filtering
4704 larger -> stronger filtering
4707 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4710 Stretch luminance to @code{0-255}.
4713 @item lb/linblenddeint
4714 Linear blend deinterlacing filter that deinterlaces the given block by
4715 filtering all lines with a @code{(1 2 1)} filter.
4717 @item li/linipoldeint
4718 Linear interpolating deinterlacing filter that deinterlaces the given block by
4719 linearly interpolating every second line.
4721 @item ci/cubicipoldeint
4722 Cubic interpolating deinterlacing filter deinterlaces the given block by
4723 cubically interpolating every second line.
4725 @item md/mediandeint
4726 Median deinterlacing filter that deinterlaces the given block by applying a
4727 median filter to every second line.
4729 @item fd/ffmpegdeint
4730 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4731 second line with a @code{(-1 4 2 4 -1)} filter.
4734 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4735 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4737 @item fq/forceQuant[|quantizer]
4738 Overrides the quantizer table from the input with the constant quantizer you
4746 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4749 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4752 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4755 @subsection Examples
4759 Apply horizontal and vertical deblocking, deringing and automatic
4760 brightness/contrast:
4766 Apply default filters without brightness/contrast correction:
4772 Apply default filters and temporal denoiser:
4774 pp=default/tmpnoise|1|2|3
4778 Apply deblocking on luminance only, and switch vertical deblocking on or off
4779 automatically depending on available CPU time:
4787 Suppress a TV station logo, using an image file to determine which
4788 pixels comprise the logo. It works by filling in the pixels that
4789 comprise the logo with neighboring pixels.
4791 The filters accept the following options:
4795 Set the filter bitmap file, which can be any image format supported by
4796 libavformat. The width and height of the image file must match those of the
4797 video stream being processed.
4800 Pixels in the provided bitmap image with a value of zero are not
4801 considered part of the logo, non-zero pixels are considered part of
4802 the logo. If you use white (255) for the logo and black (0) for the
4803 rest, you will be safe. For making the filter bitmap, it is
4804 recommended to take a screen capture of a black frame with the logo
4805 visible, and then using a threshold filter followed by the erode
4806 filter once or twice.
4808 If needed, little splotches can be fixed manually. Remember that if
4809 logo pixels are not covered, the filter quality will be much
4810 reduced. Marking too many pixels as part of the logo does not hurt as
4811 much, but it will increase the amount of blurring needed to cover over
4812 the image and will destroy more information than necessary, and extra
4813 pixels will slow things down on a large logo.
4817 Scale (resize) the input video, using the libswscale library.
4819 The scale filter forces the output display aspect ratio to be the same
4820 of the input, by changing the output sample aspect ratio.
4822 This filter accepts a list of named options in the form of
4823 @var{key}=@var{value} pairs separated by ":". If the key for the first
4824 two options is not specified, the assumed keys for the first two
4825 values are @code{w} and @code{h}. If the first option has no key and
4826 can be interpreted like a video size specification, it will be used
4827 to set the video size.
4829 A description of the accepted options follows.
4834 default value is @code{iw}. See below
4835 for the list of accepted constants.
4838 Output video height.
4839 default value is @code{ih}.
4840 See below for the list of accepted constants.
4843 Set the interlacing. It accepts the following values:
4847 force interlaced aware scaling
4850 do not apply interlaced scaling
4853 select interlaced aware scaling depending on whether the source frames
4854 are flagged as interlaced or not
4857 Default value is @code{0}.
4860 Set libswscale scaling flags. If not explictly specified the filter
4861 applies a bilinear scaling algorithm.
4864 Set the video size, the value must be a valid abbreviation or in the
4865 form @var{width}x@var{height}.
4868 The values of the @var{w} and @var{h} options are expressions
4869 containing the following constants:
4873 the input width and height
4876 same as @var{in_w} and @var{in_h}
4879 the output (cropped) width and height
4882 same as @var{out_w} and @var{out_h}
4885 same as @var{iw} / @var{ih}
4888 input sample aspect ratio
4891 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4894 horizontal and vertical chroma subsample values. For example for the
4895 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4898 If the input image format is different from the format requested by
4899 the next filter, the scale filter will convert the input to the
4902 If the value for @var{w} or @var{h} is 0, the respective input
4903 size is used for the output.
4905 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4906 respective output size, a value that maintains the aspect ratio of the input
4909 @subsection Examples
4913 Scale the input video to a size of 200x100:
4918 This is equivalent to:
4929 Specify a size abbreviation for the output size:
4934 which can also be written as:
4940 Scale the input to 2x:
4946 The above is the same as:
4952 Scale the input to 2x with forced interlaced scaling:
4954 scale=2*iw:2*ih:interl=1
4958 Scale the input to half size:
4964 Increase the width, and set the height to the same size:
4970 Seek for Greek harmony:
4977 Increase the height, and set the width to 3/2 of the height:
4979 scale=w=3/2*oh:h=3/5*ih
4983 Increase the size, but make the size a multiple of the chroma
4986 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4990 Increase the width to a maximum of 500 pixels, keep the same input
4993 scale=w='min(500\, iw*3/2):h=-1'
4997 @section separatefields
4999 The @code{separatefields} takes a frame-based video input and splits
5000 each frame into its components fields, producing a new half height clip
5001 with twice the frame rate and twice the frame count.
5003 This filter use field-dominance information in frame to decide which
5004 of each pair of fields to place first in the output.
5005 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
5007 @section setdar, setsar
5009 The @code{setdar} filter sets the Display Aspect Ratio for the filter
5012 This is done by changing the specified Sample (aka Pixel) Aspect
5013 Ratio, according to the following equation:
5015 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
5018 Keep in mind that the @code{setdar} filter does not modify the pixel
5019 dimensions of the video frame. Also the display aspect ratio set by
5020 this filter may be changed by later filters in the filterchain,
5021 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5024 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5025 the filter output video.
5027 Note that as a consequence of the application of this filter, the
5028 output display aspect ratio will change according to the equation
5031 Keep in mind that the sample aspect ratio set by the @code{setsar}
5032 filter may be changed by later filters in the filterchain, e.g. if
5033 another "setsar" or a "setdar" filter is applied.
5035 The filters accept the following options:
5038 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
5039 Set the aspect ratio used by the filter.
5041 The parameter can be a floating point number string, an expression, or
5042 a string of the form @var{num}:@var{den}, where @var{num} and
5043 @var{den} are the numerator and denominator of the aspect ratio. If
5044 the parameter is not specified, it is assumed the value "0".
5045 In case the form "@var{num}:@var{den}" the @code{:} character should
5049 Set the maximum integer value to use for expressing numerator and
5050 denominator when reducing the expressed aspect ratio to a rational.
5051 Default value is @code{100}.
5055 @subsection Examples
5060 To change the display aspect ratio to 16:9, specify one of the following:
5068 To change the sample aspect ratio to 10:11, specify:
5074 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5075 1000 in the aspect ratio reduction, use the command:
5077 setdar=ratio=16/9:max=1000
5085 Force field for the output video frame.
5087 The @code{setfield} filter marks the interlace type field for the
5088 output frames. It does not change the input frame, but only sets the
5089 corresponding property, which affects how the frame is treated by
5090 following filters (e.g. @code{fieldorder} or @code{yadif}).
5092 The filter accepts the following options:
5097 Available values are:
5101 Keep the same field property.
5104 Mark the frame as bottom-field-first.
5107 Mark the frame as top-field-first.
5110 Mark the frame as progressive.
5116 Show a line containing various information for each input video frame.
5117 The input video is not modified.
5119 The shown line contains a sequence of key/value pairs of the form
5120 @var{key}:@var{value}.
5122 A description of each shown parameter follows:
5126 sequential number of the input frame, starting from 0
5129 Presentation TimeStamp of the input frame, expressed as a number of
5130 time base units. The time base unit depends on the filter input pad.
5133 Presentation TimeStamp of the input frame, expressed as a number of
5137 position of the frame in the input stream, -1 if this information in
5138 unavailable and/or meaningless (for example in case of synthetic video)
5144 sample aspect ratio of the input frame, expressed in the form
5148 size of the input frame, expressed in the form
5149 @var{width}x@var{height}
5152 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5153 for bottom field first)
5156 1 if the frame is a key frame, 0 otherwise
5159 picture type of the input frame ("I" for an I-frame, "P" for a
5160 P-frame, "B" for a B-frame, "?" for unknown type).
5161 Check also the documentation of the @code{AVPictureType} enum and of
5162 the @code{av_get_picture_type_char} function defined in
5163 @file{libavutil/avutil.h}.
5166 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5168 @item plane_checksum
5169 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5170 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5175 Blur the input video without impacting the outlines.
5177 The filter accepts the following options:
5180 @item luma_radius, lr
5181 Set the luma radius. The option value must be a float number in
5182 the range [0.1,5.0] that specifies the variance of the gaussian filter
5183 used to blur the image (slower if larger). Default value is 1.0.
5185 @item luma_strength, ls
5186 Set the luma strength. The option value must be a float number
5187 in the range [-1.0,1.0] that configures the blurring. A value included
5188 in [0.0,1.0] will blur the image whereas a value included in
5189 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5191 @item luma_threshold, lt
5192 Set the luma threshold used as a coefficient to determine
5193 whether a pixel should be blurred or not. The option value must be an
5194 integer in the range [-30,30]. A value of 0 will filter all the image,
5195 a value included in [0,30] will filter flat areas and a value included
5196 in [-30,0] will filter edges. Default value is 0.
5198 @item chroma_radius, cr
5199 Set the chroma radius. The option value must be a float number in
5200 the range [0.1,5.0] that specifies the variance of the gaussian filter
5201 used to blur the image (slower if larger). Default value is 1.0.
5203 @item chroma_strength, cs
5204 Set the chroma strength. The option value must be a float number
5205 in the range [-1.0,1.0] that configures the blurring. A value included
5206 in [0.0,1.0] will blur the image whereas a value included in
5207 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5209 @item chroma_threshold, ct
5210 Set the chroma threshold used as a coefficient to determine
5211 whether a pixel should be blurred or not. The option value must be an
5212 integer in the range [-30,30]. A value of 0 will filter all the image,
5213 a value included in [0,30] will filter flat areas and a value included
5214 in [-30,0] will filter edges. Default value is 0.
5217 If a chroma option is not explicitly set, the corresponding luma value
5222 Convert between different stereoscopic image formats.
5224 The filters accept the following options:
5228 Set stereoscopic image format of input.
5230 Available values for input image formats are:
5233 side by side parallel (left eye left, right eye right)
5236 side by side crosseye (right eye left, left eye right)
5239 side by side parallel with half width resolution
5240 (left eye left, right eye right)
5243 side by side crosseye with half width resolution
5244 (right eye left, left eye right)
5247 above-below (left eye above, right eye below)
5250 above-below (right eye above, left eye below)
5253 above-below with half height resolution
5254 (left eye above, right eye below)
5257 above-below with half height resolution
5258 (right eye above, left eye below)
5260 Default value is @samp{sbsl}.
5264 Set stereoscopic image format of output.
5266 Available values for output image formats are all the input formats as well as:
5269 anaglyph red/blue gray
5270 (red filter on left eye, blue filter on right eye)
5273 anaglyph red/green gray
5274 (red filter on left eye, green filter on right eye)
5277 anaglyph red/cyan gray
5278 (red filter on left eye, cyan filter on right eye)
5281 anaglyph red/cyan half colored
5282 (red filter on left eye, cyan filter on right eye)
5285 anaglyph red/cyan color
5286 (red filter on left eye, cyan filter on right eye)
5289 anaglyph red/cyan color optimized with the least squares projection of dubois
5290 (red filter on left eye, cyan filter on right eye)
5293 anaglyph green/magenta gray
5294 (green filter on left eye, magenta filter on right eye)
5297 anaglyph green/magenta half colored
5298 (green filter on left eye, magenta filter on right eye)
5301 anaglyph green/magenta colored
5302 (green filter on left eye, magenta filter on right eye)
5305 anaglyph green/magenta color optimized with the least squares projection of dubois
5306 (green filter on left eye, magenta filter on right eye)
5309 anaglyph yellow/blue gray
5310 (yellow filter on left eye, blue filter on right eye)
5313 anaglyph yellow/blue half colored
5314 (yellow filter on left eye, blue filter on right eye)
5317 anaglyph yellow/blue colored
5318 (yellow filter on left eye, blue filter on right eye)
5321 anaglyph yellow/blue color optimized with the least squares projection of dubois
5322 (yellow filter on left eye, blue filter on right eye)
5325 interleaved rows (left eye has top row, right eye starts on next row)
5328 interleaved rows (right eye has top row, left eye starts on next row)
5331 mono output (left eye only)
5334 mono output (right eye only)
5337 Default value is @samp{arcd}.
5343 Draw subtitles on top of input video using the libass library.
5345 To enable compilation of this filter you need to configure FFmpeg with
5346 @code{--enable-libass}. This filter also requires a build with libavcodec and
5347 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5348 Alpha) subtitles format.
5350 The filter accepts the following options:
5354 Set the filename of the subtitle file to read. It must be specified.
5357 Specify the size of the original video, the video for which the ASS file
5358 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5359 necessary to correctly scale the fonts if the aspect ratio has been changed.
5362 Set subtitles input character encoding. @code{subtitles} filter only. Only
5363 useful if not UTF-8.
5366 If the first key is not specified, it is assumed that the first value
5367 specifies the @option{filename}.
5369 For example, to render the file @file{sub.srt} on top of the input
5370 video, use the command:
5375 which is equivalent to:
5377 subtitles=filename=sub.srt
5382 Split input video into several identical outputs.
5384 The filter accepts a single parameter which specifies the number of outputs. If
5385 unspecified, it defaults to 2.
5389 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5391 will create 5 copies of the input video.
5395 [in] split [splitout1][splitout2];
5396 [splitout1] crop=100:100:0:0 [cropout];
5397 [splitout2] pad=200:200:100:100 [padout];
5400 will create two separate outputs from the same input, one cropped and
5405 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5406 Interpolate) pixel art scaling algorithm.
5408 Useful for enlarging pixel art images without reducing sharpness.
5414 Select the most representative frame in a given sequence of consecutive frames.
5416 The filter accepts the following options:
5420 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5421 will pick one of them, and then handle the next batch of @var{n} frames until
5422 the end. Default is @code{100}.
5425 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5426 value will result in a higher memory usage, so a high value is not recommended.
5428 @subsection Examples
5432 Extract one picture each 50 frames:
5438 Complete example of a thumbnail creation with @command{ffmpeg}:
5440 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5446 Tile several successive frames together.
5448 The filter accepts the following options:
5453 Set the grid size (i.e. the number of lines and columns) in the form
5457 Set the maximum number of frames to render in the given area. It must be less
5458 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5459 the area will be used.
5462 Set the outer border margin in pixels.
5465 Set the inner border thickness (i.e. the number of pixels between frames). For
5466 more advanced padding options (such as having different values for the edges),
5467 refer to the pad video filter.
5471 @subsection Examples
5475 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5477 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5479 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5480 duplicating each output frame to accomodate the originally detected frame
5484 Display @code{5} pictures in an area of @code{3x2} frames,
5485 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5486 mixed flat and named options:
5488 tile=3x2:nb_frames=5:padding=7:margin=2
5494 Perform various types of temporal field interlacing.
5496 Frames are counted starting from 1, so the first input frame is
5499 The filter accepts the following options:
5504 Specify the mode of the interlacing. This option can also be specified
5505 as a value alone. See below for a list of values for this option.
5507 Available values are:
5511 Move odd frames into the upper field, even into the lower field,
5512 generating a double height frame at half frame rate.
5515 Only output even frames, odd frames are dropped, generating a frame with
5516 unchanged height at half frame rate.
5519 Only output odd frames, even frames are dropped, generating a frame with
5520 unchanged height at half frame rate.
5523 Expand each frame to full height, but pad alternate lines with black,
5524 generating a frame with double height at the same input frame rate.
5526 @item interleave_top, 4
5527 Interleave the upper field from odd frames with the lower field from
5528 even frames, generating a frame with unchanged height at half frame rate.
5530 @item interleave_bottom, 5
5531 Interleave the lower field from odd frames with the upper field from
5532 even frames, generating a frame with unchanged height at half frame rate.
5534 @item interlacex2, 6
5535 Double frame rate with unchanged height. Frames are inserted each
5536 containing the second temporal field from the previous input frame and
5537 the first temporal field from the next input frame. This mode relies on
5538 the top_field_first flag. Useful for interlaced video displays with no
5539 field synchronisation.
5542 Numeric values are deprecated but are accepted for backward
5543 compatibility reasons.
5545 Default mode is @code{merge}.
5548 Specify flags influencing the filter process.
5550 Available value for @var{flags} is:
5553 @item low_pass_filter, vlfp
5554 Enable vertical low-pass filtering in the filter.
5555 Vertical low-pass filtering is required when creating an interlaced
5556 destination from a progressive source which contains high-frequency
5557 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5560 Vertical low-pass filtering can only be enabled for @option{mode}
5561 @var{interleave_top} and @var{interleave_bottom}.
5568 Transpose rows with columns in the input video and optionally flip it.
5570 This filter accepts the following options:
5575 The direction of the transpose.
5578 @item 0, 4, cclock_flip
5579 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5587 Rotate by 90 degrees clockwise, that is:
5595 Rotate by 90 degrees counterclockwise, that is:
5602 @item 3, 7, clock_flip
5603 Rotate by 90 degrees clockwise and vertically flip, that is:
5611 For values between 4-7, the transposition is only done if the input
5612 video geometry is portrait and not landscape. These values are
5613 deprecated, the @code{passthrough} option should be used instead.
5616 Do not apply the transposition if the input geometry matches the one
5617 specified by the specified value. It accepts the following values:
5620 Always apply transposition.
5622 Preserve portrait geometry (when @var{height} >= @var{width}).
5624 Preserve landscape geometry (when @var{width} >= @var{height}).
5627 Default value is @code{none}.
5630 For example to rotate by 90 degrees clockwise and preserve portrait
5633 transpose=dir=1:passthrough=portrait
5636 The command above can also be specified as:
5638 transpose=1:portrait
5643 Sharpen or blur the input video.
5645 It accepts the following parameters:
5648 @item luma_msize_x, lx
5649 @item chroma_msize_x, cx
5650 Set the luma/chroma matrix horizontal size. It must be an odd integer
5651 between 3 and 63, default value is 5.
5653 @item luma_msize_y, ly
5654 @item chroma_msize_y, cy
5655 Set the luma/chroma matrix vertical size. It must be an odd integer
5656 between 3 and 63, default value is 5.
5658 @item luma_amount, la
5659 @item chroma_amount, ca
5660 Set the luma/chroma effect strength. It can be a float number,
5661 reasonable values lay between -1.5 and 1.5.
5663 Negative values will blur the input video, while positive values will
5664 sharpen it, a value of zero will disable the effect.
5666 Default value is 1.0 for @option{luma_amount}, 0.0 for
5667 @option{chroma_amount}.
5670 All parameters are optional and default to the
5671 equivalent of the string '5:5:1.0:5:5:0.0'.
5673 @subsection Examples
5677 Apply strong luma sharpen effect:
5679 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5683 Apply strong blur of both luma and chroma parameters:
5685 unsharp=7:7:-2:7:7:-2
5691 Flip the input video vertically.
5694 ffmpeg -i in.avi -vf "vflip" out.avi
5699 Deinterlace the input video ("yadif" means "yet another deinterlacing
5702 This filter accepts the following options:
5708 The interlacing mode to adopt, accepts one of the following values:
5712 output 1 frame for each frame
5714 output 1 frame for each field
5715 @item 2, send_frame_nospatial
5716 like @code{send_frame} but skip spatial interlacing check
5717 @item 3, send_field_nospatial
5718 like @code{send_field} but skip spatial interlacing check
5721 Default value is @code{send_frame}.
5724 The picture field parity assumed for the input interlaced video, accepts one of
5725 the following values:
5729 assume top field first
5731 assume bottom field first
5733 enable automatic detection
5736 Default value is @code{auto}.
5737 If interlacing is unknown or decoder does not export this information,
5738 top field first will be assumed.
5741 Specify which frames to deinterlace. Accept one of the following
5746 deinterlace all frames
5748 only deinterlace frames marked as interlaced
5751 Default value is @code{all}.
5754 @c man end VIDEO FILTERS
5756 @chapter Video Sources
5757 @c man begin VIDEO SOURCES
5759 Below is a description of the currently available video sources.
5763 Buffer video frames, and make them available to the filter chain.
5765 This source is mainly intended for a programmatic use, in particular
5766 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5768 It accepts a list of options in the form of @var{key}=@var{value} pairs
5769 separated by ":". A description of the accepted options follows.
5774 Specify the size (width and height) of the buffered video frames.
5783 A string representing the pixel format of the buffered video frames.
5784 It may be a number corresponding to a pixel format, or a pixel format
5788 Specify the timebase assumed by the timestamps of the buffered frames.
5791 Specify the frame rate expected for the video stream.
5793 @item pixel_aspect, sar
5794 Specify the sample aspect ratio assumed by the video frames.
5797 Specify the optional parameters to be used for the scale filter which
5798 is automatically inserted when an input change is detected in the
5799 input size or format.
5804 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
5807 will instruct the source to accept video frames with size 320x240 and
5808 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5809 square pixels (1:1 sample aspect ratio).
5810 Since the pixel format with name "yuv410p" corresponds to the number 6
5811 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5812 this example corresponds to:
5814 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5817 Alternatively, the options can be specified as a flat string, but this
5818 syntax is deprecated:
5820 @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}]
5824 Create a pattern generated by an elementary cellular automaton.
5826 The initial state of the cellular automaton can be defined through the
5827 @option{filename}, and @option{pattern} options. If such options are
5828 not specified an initial state is created randomly.
5830 At each new frame a new row in the video is filled with the result of
5831 the cellular automaton next generation. The behavior when the whole
5832 frame is filled is defined by the @option{scroll} option.
5834 This source accepts the following options:
5838 Read the initial cellular automaton state, i.e. the starting row, from
5840 In the file, each non-whitespace character is considered an alive
5841 cell, a newline will terminate the row, and further characters in the
5842 file will be ignored.
5845 Read the initial cellular automaton state, i.e. the starting row, from
5846 the specified string.
5848 Each non-whitespace character in the string is considered an alive
5849 cell, a newline will terminate the row, and further characters in the
5850 string will be ignored.
5853 Set the video rate, that is the number of frames generated per second.
5856 @item random_fill_ratio, ratio
5857 Set the random fill ratio for the initial cellular automaton row. It
5858 is a floating point number value ranging from 0 to 1, defaults to
5861 This option is ignored when a file or a pattern is specified.
5863 @item random_seed, seed
5864 Set the seed for filling randomly the initial row, must be an integer
5865 included between 0 and UINT32_MAX. If not specified, or if explicitly
5866 set to -1, the filter will try to use a good random seed on a best
5870 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5871 Default value is 110.
5874 Set the size of the output video.
5876 If @option{filename} or @option{pattern} is specified, the size is set
5877 by default to the width of the specified initial state row, and the
5878 height is set to @var{width} * PHI.
5880 If @option{size} is set, it must contain the width of the specified
5881 pattern string, and the specified pattern will be centered in the
5884 If a filename or a pattern string is not specified, the size value
5885 defaults to "320x518" (used for a randomly generated initial state).
5888 If set to 1, scroll the output upward when all the rows in the output
5889 have been already filled. If set to 0, the new generated row will be
5890 written over the top row just after the bottom row is filled.
5893 @item start_full, full
5894 If set to 1, completely fill the output with generated rows before
5895 outputting the first frame.
5896 This is the default behavior, for disabling set the value to 0.
5899 If set to 1, stitch the left and right row edges together.
5900 This is the default behavior, for disabling set the value to 0.
5903 @subsection Examples
5907 Read the initial state from @file{pattern}, and specify an output of
5910 cellauto=f=pattern:s=200x400
5914 Generate a random initial row with a width of 200 cells, with a fill
5917 cellauto=ratio=2/3:s=200x200
5921 Create a pattern generated by rule 18 starting by a single alive cell
5922 centered on an initial row with width 100:
5924 cellauto=p=@@:s=100x400:full=0:rule=18
5928 Specify a more elaborated initial pattern:
5930 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5937 Generate a Mandelbrot set fractal, and progressively zoom towards the
5938 point specified with @var{start_x} and @var{start_y}.
5940 This source accepts the following options:
5945 Set the terminal pts value. Default value is 400.
5948 Set the terminal scale value.
5949 Must be a floating point value. Default value is 0.3.
5952 Set the inner coloring mode, that is the algorithm used to draw the
5953 Mandelbrot fractal internal region.
5955 It shall assume one of the following values:
5960 Show time until convergence.
5962 Set color based on point closest to the origin of the iterations.
5967 Default value is @var{mincol}.
5970 Set the bailout value. Default value is 10.0.
5973 Set the maximum of iterations performed by the rendering
5974 algorithm. Default value is 7189.
5977 Set outer coloring mode.
5978 It shall assume one of following values:
5980 @item iteration_count
5981 Set iteration cound mode.
5982 @item normalized_iteration_count
5983 set normalized iteration count mode.
5985 Default value is @var{normalized_iteration_count}.
5988 Set frame rate, expressed as number of frames per second. Default
5992 Set frame size. Default value is "640x480".
5995 Set the initial scale value. Default value is 3.0.
5998 Set the initial x position. Must be a floating point value between
5999 -100 and 100. Default value is -0.743643887037158704752191506114774.
6002 Set the initial y position. Must be a floating point value between
6003 -100 and 100. Default value is -0.131825904205311970493132056385139.
6008 Generate various test patterns, as generated by the MPlayer test filter.
6010 The size of the generated video is fixed, and is 256x256.
6011 This source is useful in particular for testing encoding features.
6013 This source accepts the following options:
6018 Specify the frame rate of the sourced video, as the number of frames
6019 generated per second. It has to be a string in the format
6020 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6021 number or a valid video frame rate abbreviation. The default value is
6025 Set the video duration of the sourced video. The accepted syntax is:
6030 See also the function @code{av_parse_time()}.
6032 If not specified, or the expressed duration is negative, the video is
6033 supposed to be generated forever.
6037 Set the number or the name of the test to perform. Supported tests are:
6052 Default value is "all", which will cycle through the list of all tests.
6055 For example the following:
6060 will generate a "dc_luma" test pattern.
6064 Provide a frei0r source.
6066 To enable compilation of this filter you need to install the frei0r
6067 header and configure FFmpeg with @code{--enable-frei0r}.
6069 This source accepts the following options:
6074 The size of the video to generate, may be a string of the form
6075 @var{width}x@var{height} or a frame size abbreviation.
6078 Framerate of the generated video, may be a string of the form
6079 @var{num}/@var{den} or a frame rate abbreviation.
6082 The name to the frei0r source to load. For more information regarding frei0r and
6083 how to set the parameters read the section @ref{frei0r} in the description of
6087 A '|'-separated list of parameters to pass to the frei0r source.
6091 For example, to generate a frei0r partik0l source with size 200x200
6092 and frame rate 10 which is overlayed on the overlay filter main input:
6094 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6099 Generate a life pattern.
6101 This source is based on a generalization of John Conway's life game.
6103 The sourced input represents a life grid, each pixel represents a cell
6104 which can be in one of two possible states, alive or dead. Every cell
6105 interacts with its eight neighbours, which are the cells that are
6106 horizontally, vertically, or diagonally adjacent.
6108 At each interaction the grid evolves according to the adopted rule,
6109 which specifies the number of neighbor alive cells which will make a
6110 cell stay alive or born. The @option{rule} option allows to specify
6113 This source accepts the following options:
6117 Set the file from which to read the initial grid state. In the file,
6118 each non-whitespace character is considered an alive cell, and newline
6119 is used to delimit the end of each row.
6121 If this option is not specified, the initial grid is generated
6125 Set the video rate, that is the number of frames generated per second.
6128 @item random_fill_ratio, ratio
6129 Set the random fill ratio for the initial random grid. It is a
6130 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6131 It is ignored when a file is specified.
6133 @item random_seed, seed
6134 Set the seed for filling the initial random grid, must be an integer
6135 included between 0 and UINT32_MAX. If not specified, or if explicitly
6136 set to -1, the filter will try to use a good random seed on a best
6142 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6143 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6144 @var{NS} specifies the number of alive neighbor cells which make a
6145 live cell stay alive, and @var{NB} the number of alive neighbor cells
6146 which make a dead cell to become alive (i.e. to "born").
6147 "s" and "b" can be used in place of "S" and "B", respectively.
6149 Alternatively a rule can be specified by an 18-bits integer. The 9
6150 high order bits are used to encode the next cell state if it is alive
6151 for each number of neighbor alive cells, the low order bits specify
6152 the rule for "borning" new cells. Higher order bits encode for an
6153 higher number of neighbor cells.
6154 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6155 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6157 Default value is "S23/B3", which is the original Conway's game of life
6158 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6159 cells, and will born a new cell if there are three alive cells around
6163 Set the size of the output video.
6165 If @option{filename} is specified, the size is set by default to the
6166 same size of the input file. If @option{size} is set, it must contain
6167 the size specified in the input file, and the initial grid defined in
6168 that file is centered in the larger resulting area.
6170 If a filename is not specified, the size value defaults to "320x240"
6171 (used for a randomly generated initial grid).
6174 If set to 1, stitch the left and right grid edges together, and the
6175 top and bottom edges also. Defaults to 1.
6178 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6179 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6180 value from 0 to 255.
6183 Set the color of living (or new born) cells.
6186 Set the color of dead cells. If @option{mold} is set, this is the first color
6187 used to represent a dead cell.
6190 Set mold color, for definitely dead and moldy cells.
6193 @subsection Examples
6197 Read a grid from @file{pattern}, and center it on a grid of size
6200 life=f=pattern:s=300x300
6204 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6206 life=ratio=2/3:s=200x200
6210 Specify a custom rule for evolving a randomly generated grid:
6216 Full example with slow death effect (mold) using @command{ffplay}:
6218 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6222 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6224 The @code{color} source provides an uniformly colored input.
6226 The @code{nullsrc} source returns unprocessed video frames. It is
6227 mainly useful to be employed in analysis / debugging tools, or as the
6228 source for filters which ignore the input data.
6230 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6231 detecting RGB vs BGR issues. You should see a red, green and blue
6232 stripe from top to bottom.
6234 The @code{smptebars} source generates a color bars pattern, based on
6235 the SMPTE Engineering Guideline EG 1-1990.
6237 The @code{testsrc} source generates a test video pattern, showing a
6238 color pattern, a scrolling gradient and a timestamp. This is mainly
6239 intended for testing purposes.
6241 The sources accept the following options:
6246 Specify the color of the source, only used in the @code{color}
6247 source. It can be the name of a color (case insensitive match) or a
6248 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6249 default value is "black".
6252 Specify the size of the sourced video, it may be a string of the form
6253 @var{width}x@var{height}, or the name of a size abbreviation. The
6254 default value is "320x240".
6257 Specify the frame rate of the sourced video, as the number of frames
6258 generated per second. It has to be a string in the format
6259 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6260 number or a valid video frame rate abbreviation. The default value is
6264 Set the sample aspect ratio of the sourced video.
6267 Set the video duration of the sourced video. The accepted syntax is:
6269 [-]HH[:MM[:SS[.m...]]]
6272 See also the function @code{av_parse_time()}.
6274 If not specified, or the expressed duration is negative, the video is
6275 supposed to be generated forever.
6278 Set the number of decimals to show in the timestamp, only used in the
6279 @code{testsrc} source.
6281 The displayed timestamp value will correspond to the original
6282 timestamp value multiplied by the power of 10 of the specified
6283 value. Default value is 0.
6286 For example the following:
6288 testsrc=duration=5.3:size=qcif:rate=10
6291 will generate a video with a duration of 5.3 seconds, with size
6292 176x144 and a frame rate of 10 frames per second.
6294 The following graph description will generate a red source
6295 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6298 color=c=red@@0.2:s=qcif:r=10
6301 If the input content is to be ignored, @code{nullsrc} can be used. The
6302 following command generates noise in the luminance plane by employing
6303 the @code{geq} filter:
6305 nullsrc=s=256x256, geq=random(1)*255:128:128
6308 @c man end VIDEO SOURCES
6310 @chapter Video Sinks
6311 @c man begin VIDEO SINKS
6313 Below is a description of the currently available video sinks.
6317 Buffer video frames, and make them available to the end of the filter
6320 This sink is mainly intended for a programmatic use, in particular
6321 through the interface defined in @file{libavfilter/buffersink.h}.
6323 It does not require a string parameter in input, but you need to
6324 specify a pointer to a list of supported pixel formats terminated by
6325 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6326 when initializing this sink.
6330 Null video sink, do absolutely nothing with the input video. It is
6331 mainly useful as a template and to be employed in analysis / debugging
6334 @c man end VIDEO SINKS
6336 @chapter Multimedia Filters
6337 @c man begin MULTIMEDIA FILTERS
6339 Below is a description of the currently available multimedia filters.
6341 @section aperms, perms
6343 Set read/write permissions for the output frames.
6345 These filters are mainly aimed at developers to test direct path in the
6346 following filter in the filtergraph.
6348 The filters accept the following options:
6352 Select the permissions mode.
6354 It accepts the following values:
6357 Do nothing. This is the default.
6359 Set all the output frames read-only.
6361 Set all the output frames directly writable.
6363 Make the frame read-only if writable, and writable if read-only.
6365 Set each output frame read-only or writable randomly.
6369 Set the seed for the @var{random} mode, must be an integer included between
6370 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6371 @code{-1}, the filter will try to use a good random seed on a best effort
6375 Note: in case of auto-inserted filter between the permission filter and the
6376 following one, the permission might not be received as expected in that
6377 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6378 perms/aperms filter can avoid this problem.
6381 Add a phasing effect to the input audio.
6383 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6384 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6386 A description of the accepted parameters follows.
6390 Set input gain. Default is 0.4.
6393 Set output gain. Default is 0.74
6396 Set delay in milliseconds. Default is 3.0.
6399 Set decay. Default is 0.4.
6402 Set modulation speed in Hz. Default is 0.5.
6405 Set modulation type. Default is triangular.
6407 It accepts the following values:
6414 @section aselect, select
6415 Select frames to pass in output.
6417 This filter accepts the following options:
6422 An expression, which is evaluated for each input frame. If the expression is
6423 evaluated to a non-zero value, the frame is selected and passed to the output,
6424 otherwise it is discarded.
6428 The expression can contain the following constants:
6432 the sequential number of the filtered frame, starting from 0
6435 the sequential number of the selected frame, starting from 0
6437 @item prev_selected_n
6438 the sequential number of the last selected frame, NAN if undefined
6441 timebase of the input timestamps
6444 the PTS (Presentation TimeStamp) of the filtered video frame,
6445 expressed in @var{TB} units, NAN if undefined
6448 the PTS (Presentation TimeStamp) of the filtered video frame,
6449 expressed in seconds, NAN if undefined
6452 the PTS of the previously filtered video frame, NAN if undefined
6454 @item prev_selected_pts
6455 the PTS of the last previously filtered video frame, NAN if undefined
6457 @item prev_selected_t
6458 the PTS of the last previously selected video frame, NAN if undefined
6461 the PTS of the first video frame in the video, NAN if undefined
6464 the time of the first video frame in the video, NAN if undefined
6466 @item pict_type @emph{(video only)}
6467 the type of the filtered frame, can assume one of the following
6479 @item interlace_type @emph{(video only)}
6480 the frame interlace type, can assume one of the following values:
6483 the frame is progressive (not interlaced)
6485 the frame is top-field-first
6487 the frame is bottom-field-first
6490 @item consumed_sample_n @emph{(audio only)}
6491 the number of selected samples before the current frame
6493 @item samples_n @emph{(audio only)}
6494 the number of samples in the current frame
6496 @item sample_rate @emph{(audio only)}
6497 the input sample rate
6500 1 if the filtered frame is a key-frame, 0 otherwise
6503 the position in the file of the filtered frame, -1 if the information
6504 is not available (e.g. for synthetic video)
6506 @item scene @emph{(video only)}
6507 value between 0 and 1 to indicate a new scene; a low value reflects a low
6508 probability for the current frame to introduce a new scene, while a higher
6509 value means the current frame is more likely to be one (see the example below)
6513 The default value of the select expression is "1".
6515 @subsection Examples
6519 Select all frames in input:
6524 The example above is the same as:
6536 Select only I-frames:
6538 select='eq(pict_type\,I)'
6542 Select one frame every 100:
6544 select='not(mod(n\,100))'
6548 Select only frames contained in the 10-20 time interval:
6550 select='gte(t\,10)*lte(t\,20)'
6554 Select only I frames contained in the 10-20 time interval:
6556 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6560 Select frames with a minimum distance of 10 seconds:
6562 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6566 Use aselect to select only audio frames with samples number > 100:
6568 aselect='gt(samples_n\,100)'
6572 Create a mosaic of the first scenes:
6574 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6577 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6581 @section asendcmd, sendcmd
6583 Send commands to filters in the filtergraph.
6585 These filters read commands to be sent to other filters in the
6588 @code{asendcmd} must be inserted between two audio filters,
6589 @code{sendcmd} must be inserted between two video filters, but apart
6590 from that they act the same way.
6592 The specification of commands can be provided in the filter arguments
6593 with the @var{commands} option, or in a file specified by the
6594 @var{filename} option.
6596 These filters accept the following options:
6599 Set the commands to be read and sent to the other filters.
6601 Set the filename of the commands to be read and sent to the other
6605 @subsection Commands syntax
6607 A commands description consists of a sequence of interval
6608 specifications, comprising a list of commands to be executed when a
6609 particular event related to that interval occurs. The occurring event
6610 is typically the current frame time entering or leaving a given time
6613 An interval is specified by the following syntax:
6615 @var{START}[-@var{END}] @var{COMMANDS};
6618 The time interval is specified by the @var{START} and @var{END} times.
6619 @var{END} is optional and defaults to the maximum time.
6621 The current frame time is considered within the specified interval if
6622 it is included in the interval [@var{START}, @var{END}), that is when
6623 the time is greater or equal to @var{START} and is lesser than
6626 @var{COMMANDS} consists of a sequence of one or more command
6627 specifications, separated by ",", relating to that interval. The
6628 syntax of a command specification is given by:
6630 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6633 @var{FLAGS} is optional and specifies the type of events relating to
6634 the time interval which enable sending the specified command, and must
6635 be a non-null sequence of identifier flags separated by "+" or "|" and
6636 enclosed between "[" and "]".
6638 The following flags are recognized:
6641 The command is sent when the current frame timestamp enters the
6642 specified interval. In other words, the command is sent when the
6643 previous frame timestamp was not in the given interval, and the
6647 The command is sent when the current frame timestamp leaves the
6648 specified interval. In other words, the command is sent when the
6649 previous frame timestamp was in the given interval, and the
6653 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6656 @var{TARGET} specifies the target of the command, usually the name of
6657 the filter class or a specific filter instance name.
6659 @var{COMMAND} specifies the name of the command for the target filter.
6661 @var{ARG} is optional and specifies the optional list of argument for
6662 the given @var{COMMAND}.
6664 Between one interval specification and another, whitespaces, or
6665 sequences of characters starting with @code{#} until the end of line,
6666 are ignored and can be used to annotate comments.
6668 A simplified BNF description of the commands specification syntax
6671 @var{COMMAND_FLAG} ::= "enter" | "leave"
6672 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6673 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6674 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6675 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6676 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6679 @subsection Examples
6683 Specify audio tempo change at second 4:
6685 asendcmd=c='4.0 atempo tempo 1.5',atempo
6689 Specify a list of drawtext and hue commands in a file.
6691 # show text in the interval 5-10
6692 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6693 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6695 # desaturate the image in the interval 15-20
6696 15.0-20.0 [enter] hue s 0,
6697 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6699 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6701 # apply an exponential saturation fade-out effect, starting from time 25
6702 25 [enter] hue s exp(25-t)
6705 A filtergraph allowing to read and process the above command list
6706 stored in a file @file{test.cmd}, can be specified with:
6708 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6713 @section asetpts, setpts
6715 Change the PTS (presentation timestamp) of the input frames.
6717 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6719 This filter accepts the following options:
6724 The expression which is evaluated for each frame to construct its timestamp.
6728 The expression is evaluated through the eval API and can contain the following
6733 frame rate, only defined for constant frame-rate video
6736 the presentation timestamp in input
6739 the count of the input frame, starting from 0.
6741 @item NB_CONSUMED_SAMPLES
6742 the number of consumed samples, not including the current frame (only
6746 the number of samples in the current frame (only audio)
6752 the PTS of the first frame
6755 the time in seconds of the first frame
6758 tell if the current frame is interlaced
6761 the time in seconds of the current frame
6767 original position in the file of the frame, or undefined if undefined
6768 for the current frame
6774 previous input time in seconds
6780 previous output time in seconds
6783 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6787 wallclock (RTC) time at the start of the movie in microseconds
6790 @subsection Examples
6794 Start counting PTS from zero
6800 Apply fast motion effect:
6806 Apply slow motion effect:
6812 Set fixed rate of 25 frames per second:
6818 Set fixed rate 25 fps with some jitter:
6820 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6824 Apply an offset of 10 seconds to the input PTS:
6830 Generate timestamps from a "live source" and rebase onto the current timebase:
6832 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6838 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6839 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6840 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6841 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6843 The filter also has a video output (see the @var{video} option) with a real
6844 time graph to observe the loudness evolution. The graphic contains the logged
6845 message mentioned above, so it is not printed anymore when this option is set,
6846 unless the verbose logging is set. The main graphing area contains the
6847 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6848 the momentary loudness (400 milliseconds).
6850 More information about the Loudness Recommendation EBU R128 on
6851 @url{http://tech.ebu.ch/loudness}.
6853 The filter accepts the following options:
6858 Activate the video output. The audio stream is passed unchanged whether this
6859 option is set or no. The video stream will be the first output stream if
6860 activated. Default is @code{0}.
6863 Set the video size. This option is for video only. Default and minimum
6864 resolution is @code{640x480}.
6867 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6868 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6869 other integer value between this range is allowed.
6872 Set metadata injection. If set to @code{1}, the audio input will be segmented
6873 into 100ms output frames, each of them containing various loudness information
6874 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6876 Default is @code{0}.
6879 Force the frame logging level.
6881 Available values are:
6884 information logging level
6886 verbose logging level
6889 By default, the logging level is set to @var{info}. If the @option{video} or
6890 the @option{metadata} options are set, it switches to @var{verbose}.
6893 @subsection Examples
6897 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6899 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6903 Run an analysis with @command{ffmpeg}:
6905 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6909 @section settb, asettb
6911 Set the timebase to use for the output frames timestamps.
6912 It is mainly useful for testing timebase configuration.
6914 This filter accepts the following options:
6919 The expression which is evaluated into the output timebase.
6923 The value for @option{tb} is an arithmetic expression representing a
6924 rational. The expression can contain the constants "AVTB" (the default
6925 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6926 audio only). Default value is "intb".
6928 @subsection Examples
6932 Set the timebase to 1/25:
6938 Set the timebase to 1/10:
6944 Set the timebase to 1001/1000:
6950 Set the timebase to 2*intb:
6956 Set the default timebase value:
6964 Concatenate audio and video streams, joining them together one after the
6967 The filter works on segments of synchronized video and audio streams. All
6968 segments must have the same number of streams of each type, and that will
6969 also be the number of streams at output.
6971 The filter accepts the following options:
6976 Set the number of segments. Default is 2.
6979 Set the number of output video streams, that is also the number of video
6980 streams in each segment. Default is 1.
6983 Set the number of output audio streams, that is also the number of video
6984 streams in each segment. Default is 0.
6987 Activate unsafe mode: do not fail if segments have a different format.
6991 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6992 @var{a} audio outputs.
6994 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6995 segment, in the same order as the outputs, then the inputs for the second
6998 Related streams do not always have exactly the same duration, for various
6999 reasons including codec frame size or sloppy authoring. For that reason,
7000 related synchronized streams (e.g. a video and its audio track) should be
7001 concatenated at once. The concat filter will use the duration of the longest
7002 stream in each segment (except the last one), and if necessary pad shorter
7003 audio streams with silence.
7005 For this filter to work correctly, all segments must start at timestamp 0.
7007 All corresponding streams must have the same parameters in all segments; the
7008 filtering system will automatically select a common pixel format for video
7009 streams, and a common sample format, sample rate and channel layout for
7010 audio streams, but other settings, such as resolution, must be converted
7011 explicitly by the user.
7013 Different frame rates are acceptable but will result in variable frame rate
7014 at output; be sure to configure the output file to handle it.
7016 @subsection Examples
7020 Concatenate an opening, an episode and an ending, all in bilingual version
7021 (video in stream 0, audio in streams 1 and 2):
7023 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
7024 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7025 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7026 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7030 Concatenate two parts, handling audio and video separately, using the
7031 (a)movie sources, and adjusting the resolution:
7033 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7034 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7035 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7037 Note that a desync will happen at the stitch if the audio and video streams
7038 do not have exactly the same duration in the first file.
7042 @section showspectrum
7044 Convert input audio to a video output, representing the audio frequency
7047 The filter accepts the following options:
7051 Specify the video size for the output. Default value is @code{640x512}.
7054 Specify if the spectrum should slide along the window. Default value is
7058 Specify display mode.
7060 It accepts the following values:
7063 all channels are displayed in the same row
7065 all channels are displayed in separate rows
7068 Default value is @samp{combined}.
7071 Specify display color mode.
7073 It accepts the following values:
7076 each channel is displayed in a separate color
7078 each channel is is displayed using the same color scheme
7081 Default value is @samp{channel}.
7084 Specify scale used for calculating intensity color values.
7086 It accepts the following values:
7091 square root, default
7098 Default value is @samp{sqrt}.
7101 Set saturation modifier for displayed colors. Negative values provide
7102 alternative color scheme. @code{0} is no saturation at all.
7103 Saturation must be in [-10.0, 10.0] range.
7104 Default value is @code{1}.
7107 The usage is very similar to the showwaves filter; see the examples in that
7110 @subsection Examples
7114 Large window with logarithmic color scaling:
7116 showspectrum=s=1280x480:scale=log
7120 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7122 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7123 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7129 Convert input audio to a video output, representing the samples waves.
7131 The filter accepts the following options:
7135 Specify the video size for the output. Default value is "600x240".
7140 Available values are:
7143 Draw a point for each sample.
7146 Draw a vertical line for each sample.
7149 Default value is @code{point}.
7152 Set the number of samples which are printed on the same column. A
7153 larger value will decrease the frame rate. Must be a positive
7154 integer. This option can be set only if the value for @var{rate}
7155 is not explicitly specified.
7158 Set the (approximate) output frame rate. This is done by setting the
7159 option @var{n}. Default value is "25".
7163 @subsection Examples
7167 Output the input file audio and the corresponding video representation
7170 amovie=a.mp3,asplit[out0],showwaves[out1]
7174 Create a synthetic signal and show it with showwaves, forcing a
7175 frame rate of 30 frames per second:
7177 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7181 @c man end MULTIMEDIA FILTERS
7183 @chapter Multimedia Sources
7184 @c man begin MULTIMEDIA SOURCES
7186 Below is a description of the currently available multimedia sources.
7190 This is the same as @ref{movie} source, except it selects an audio
7196 Read audio and/or video stream(s) from a movie container.
7198 This filter accepts the following options:
7202 The name of the resource to read (not necessarily a file but also a device or a
7203 stream accessed through some protocol).
7205 @item format_name, f
7206 Specifies the format assumed for the movie to read, and can be either
7207 the name of a container or an input device. If not specified the
7208 format is guessed from @var{movie_name} or by probing.
7210 @item seek_point, sp
7211 Specifies the seek point in seconds, the frames will be output
7212 starting from this seek point, the parameter is evaluated with
7213 @code{av_strtod} so the numerical value may be suffixed by an IS
7214 postfix. Default value is "0".
7217 Specifies the streams to read. Several streams can be specified,
7218 separated by "+". The source will then have as many outputs, in the
7219 same order. The syntax is explained in the ``Stream specifiers''
7220 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7221 respectively the default (best suited) video and audio stream. Default
7222 is "dv", or "da" if the filter is called as "amovie".
7224 @item stream_index, si
7225 Specifies the index of the video stream to read. If the value is -1,
7226 the best suited video stream will be automatically selected. Default
7227 value is "-1". Deprecated. If the filter is called "amovie", it will select
7228 audio instead of video.
7231 Specifies how many times to read the stream in sequence.
7232 If the value is less than 1, the stream will be read again and again.
7233 Default value is "1".
7235 Note that when the movie is looped the source timestamps are not
7236 changed, so it will generate non monotonically increasing timestamps.
7239 This filter allows to overlay a second video on top of main input of
7240 a filtergraph as shown in this graph:
7242 input -----------> deltapts0 --> overlay --> output
7245 movie --> scale--> deltapts1 -------+
7248 @subsection Examples
7252 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7253 on top of the input labelled as "in":
7255 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7256 [in] setpts=PTS-STARTPTS [main];
7257 [main][over] overlay=16:16 [out]
7261 Read from a video4linux2 device, and overlay it on top of the input
7264 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7265 [in] setpts=PTS-STARTPTS [main];
7266 [main][over] overlay=16:16 [out]
7270 Read the first video stream and the audio stream with id 0x81 from
7271 dvd.vob; the video is connected to the pad named "video" and the audio is
7272 connected to the pad named "audio":
7274 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7278 @c man end MULTIMEDIA SOURCES