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
805 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
807 ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
813 Mixes multiple audio inputs into a single output.
817 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
819 will mix 3 input audio streams to a single output with the same duration as the
820 first input and a dropout transition time of 3 seconds.
822 The filter accepts the following named parameters:
826 Number of inputs. If unspecified, it defaults to 2.
829 How to determine the end-of-stream.
833 Duration of longest input. (default)
836 Duration of shortest input.
839 Duration of first input.
843 @item dropout_transition
844 Transition time, in seconds, for volume renormalization when an input
845 stream ends. The default value is 2 seconds.
851 Pass the audio source unchanged to the output.
855 Pad the end of a audio stream with silence, this can be used together with
856 -shortest to extend audio streams to the same length as the video stream.
861 Resample the input audio to the specified parameters, using the
862 libswresample library. If none are specified then the filter will
863 automatically convert between its input and output.
865 This filter is also able to stretch/squeeze the audio data to make it match
866 the timestamps or to inject silence / cut out audio to make it match the
867 timestamps, do a combination of both or do neither.
869 The filter accepts the syntax
870 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
871 expresses a sample rate and @var{resampler_options} is a list of
872 @var{key}=@var{value} pairs, separated by ":". See the
873 ffmpeg-resampler manual for the complete list of supported options.
879 Resample the input audio to 44100Hz:
885 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
886 samples per second compensation:
892 @section asetnsamples
894 Set the number of samples per each output audio frame.
896 The last output packet may contain a different number of samples, as
897 the filter will flush all the remaining samples when the input audio
900 The filter accepts the following options:
904 @item nb_out_samples, n
905 Set the number of frames per each output audio frame. The number is
906 intended as the number of samples @emph{per each channel}.
907 Default value is 1024.
910 If set to 1, the filter will pad the last audio frame with zeroes, so
911 that the last frame will contain the same number of samples as the
912 previous ones. Default value is 1.
915 For example, to set the number of per-frame samples to 1234 and
916 disable padding for the last frame, use:
918 asetnsamples=n=1234:p=0
923 Show a line containing various information for each input audio frame.
924 The input audio is not modified.
926 The shown line contains a sequence of key/value pairs of the form
927 @var{key}:@var{value}.
929 A description of each shown parameter follows:
933 sequential number of the input frame, starting from 0
936 Presentation timestamp of the input frame, in time base units; the time base
937 depends on the filter input pad, and is usually 1/@var{sample_rate}.
940 presentation timestamp of the input frame in seconds
943 position of the frame in the input stream, -1 if this information in
944 unavailable and/or meaningless (for example in case of synthetic audio)
953 sample rate for the audio frame
956 number of samples (per channel) in the frame
959 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
960 the data is treated as if all the planes were concatenated.
962 @item plane_checksums
963 A list of Adler-32 checksums for each data plane.
968 Split input audio into several identical outputs.
970 The filter accepts a single parameter which specifies the number of outputs. If
971 unspecified, it defaults to 2.
975 [in] asplit [out0][out1]
978 will create two separate outputs from the same input.
980 To create 3 or more outputs, you need to specify the number of
983 [in] asplit=3 [out0][out1][out2]
987 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
989 will create 5 copies of the input audio.
994 Forward two audio streams and control the order the buffers are forwarded.
996 The filter accepts the following options:
1000 Set the expression deciding which stream should be
1001 forwarded next: if the result is negative, the first stream is forwarded; if
1002 the result is positive or zero, the second stream is forwarded. It can use
1003 the following variables:
1007 number of buffers forwarded so far on each stream
1009 number of samples forwarded so far on each stream
1011 current timestamp of each stream
1014 The default value is @code{t1-t2}, which means to always forward the stream
1015 that has a smaller timestamp.
1018 @subsection Examples
1020 Stress-test @code{amerge} by randomly sending buffers on the wrong
1021 input, while avoiding too much of a desynchronization:
1023 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1024 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1032 The filter accepts exactly one parameter, the audio tempo. If not
1033 specified then the filter will assume nominal 1.0 tempo. Tempo must
1034 be in the [0.5, 2.0] range.
1036 @subsection Examples
1040 Slow down audio to 80% tempo:
1046 To speed up audio to 125% tempo:
1054 Make audio easier to listen to on headphones.
1056 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1057 so that when listened to on headphones the stereo image is moved from
1058 inside your head (standard for headphones) to outside and in front of
1059 the listener (standard for speakers).
1065 Mix channels with specific gain levels. The filter accepts the output
1066 channel layout followed by a set of channels definitions.
1068 This filter is also designed to remap efficiently the channels of an audio
1071 The filter accepts parameters of the form:
1072 "@var{l}:@var{outdef}:@var{outdef}:..."
1076 output channel layout or number of channels
1079 output channel specification, of the form:
1080 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1083 output channel to define, either a channel name (FL, FR, etc.) or a channel
1084 number (c0, c1, etc.)
1087 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1090 input channel to use, see out_name for details; it is not possible to mix
1091 named and numbered input channels
1094 If the `=' in a channel specification is replaced by `<', then the gains for
1095 that specification will be renormalized so that the total is 1, thus
1096 avoiding clipping noise.
1098 @subsection Mixing examples
1100 For example, if you want to down-mix from stereo to mono, but with a bigger
1101 factor for the left channel:
1103 pan=1:c0=0.9*c0+0.1*c1
1106 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1107 7-channels surround:
1109 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1112 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1113 that should be preferred (see "-ac" option) unless you have very specific
1116 @subsection Remapping examples
1118 The channel remapping will be effective if, and only if:
1121 @item gain coefficients are zeroes or ones,
1122 @item only one input per channel output,
1125 If all these conditions are satisfied, the filter will notify the user ("Pure
1126 channel mapping detected"), and use an optimized and lossless method to do the
1129 For example, if you have a 5.1 source and want a stereo audio stream by
1130 dropping the extra channels:
1132 pan="stereo: c0=FL : c1=FR"
1135 Given the same source, you can also switch front left and front right channels
1136 and keep the input channel layout:
1138 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1141 If the input is a stereo audio stream, you can mute the front left channel (and
1142 still keep the stereo channel layout) with:
1147 Still with a stereo audio stream input, you can copy the right channel in both
1148 front left and right:
1150 pan="stereo: c0=FR : c1=FR"
1153 @section silencedetect
1155 Detect silence in an audio stream.
1157 This filter logs a message when it detects that the input audio volume is less
1158 or equal to a noise tolerance value for a duration greater or equal to the
1159 minimum detected noise duration.
1161 The printed times and duration are expressed in seconds.
1163 The filter accepts the following options:
1167 Set silence duration until notification (default is 2 seconds).
1170 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1171 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1174 @subsection Examples
1178 Detect 5 seconds of silence with -50dB noise tolerance:
1180 silencedetect=n=-50dB:d=5
1184 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1185 tolerance in @file{silence.mp3}:
1187 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
1192 Synchronize audio data with timestamps by squeezing/stretching it and/or
1193 dropping samples/adding silence when needed.
1195 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1197 The filter accepts the following named parameters:
1201 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1202 by default. When disabled, time gaps are covered with silence.
1205 Minimum difference between timestamps and audio data (in seconds) to trigger
1206 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1207 this filter, try setting this parameter to 0.
1210 Maximum compensation in samples per second. Relevant only with compensate=1.
1214 Assume the first pts should be this value. The time base is 1 / sample rate.
1215 This allows for padding/trimming at the start of stream. By default, no
1216 assumption is made about the first frame's expected pts, so no padding or
1217 trimming is done. For example, this could be set to 0 to pad the beginning with
1218 silence if an audio stream starts after the video stream or to trim any samples
1219 with a negative pts due to encoder delay.
1223 @section channelsplit
1224 Split each channel in input audio stream into a separate output stream.
1226 This filter accepts the following named parameters:
1228 @item channel_layout
1229 Channel layout of the input stream. Default is "stereo".
1232 For example, assuming a stereo input MP3 file
1234 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1236 will create an output Matroska file with two audio streams, one containing only
1237 the left channel and the other the right channel.
1239 To split a 5.1 WAV file into per-channel files
1241 ffmpeg -i in.wav -filter_complex
1242 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1243 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1244 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1249 Remap input channels to new locations.
1251 This filter accepts the following named parameters:
1253 @item channel_layout
1254 Channel layout of the output stream.
1257 Map channels from input to output. The argument is a '|'-separated list of
1258 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1259 @var{in_channel} form. @var{in_channel} can be either the name of the input
1260 channel (e.g. FL for front left) or its index in the input channel layout.
1261 @var{out_channel} is the name of the output channel or its index in the output
1262 channel layout. If @var{out_channel} is not given then it is implicitly an
1263 index, starting with zero and increasing by one for each mapping.
1266 If no mapping is present, the filter will implicitly map input channels to
1267 output channels preserving index.
1269 For example, assuming a 5.1+downmix input MOV file
1271 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1273 will create an output WAV file tagged as stereo from the downmix channels of
1276 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1278 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1282 Join multiple input streams into one multi-channel stream.
1284 The filter accepts the following named parameters:
1288 Number of input streams. Defaults to 2.
1290 @item channel_layout
1291 Desired output channel layout. Defaults to stereo.
1294 Map channels from inputs to output. The argument is a '|'-separated list of
1295 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1296 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1297 can be either the name of the input channel (e.g. FL for front left) or its
1298 index in the specified input stream. @var{out_channel} is the name of the output
1302 The filter will attempt to guess the mappings when those are not specified
1303 explicitly. It does so by first trying to find an unused matching input channel
1304 and if that fails it picks the first unused input channel.
1306 E.g. to join 3 inputs (with properly set channel layouts)
1308 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1311 To build a 5.1 output from 6 single-channel streams:
1313 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1314 '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'
1319 Convert the audio sample format, sample rate and channel layout. This filter is
1320 not meant to be used directly.
1324 Adjust the input audio volume.
1326 The filter accepts the following named parameters. If the key of the
1327 first options is omitted, the arguments are interpreted according to
1328 the following syntax:
1330 volume=@var{volume}:@var{precision}
1336 Expresses how the audio volume will be increased or decreased.
1338 Output values are clipped to the maximum value.
1340 The output audio volume is given by the relation:
1342 @var{output_volume} = @var{volume} * @var{input_volume}
1345 Default value for @var{volume} is 1.0.
1348 Set the mathematical precision.
1350 This determines which input sample formats will be allowed, which affects the
1351 precision of the volume scaling.
1355 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1357 32-bit floating-point; limits input sample format to FLT. (default)
1359 64-bit floating-point; limits input sample format to DBL.
1363 @subsection Examples
1367 Halve the input audio volume:
1371 volume=volume=-6.0206dB
1374 In all the above example the named key for @option{volume} can be
1375 omitted, for example like in:
1381 Increase input audio power by 6 decibels using fixed-point precision:
1383 volume=volume=6dB:precision=fixed
1387 @section volumedetect
1389 Detect the volume of the input video.
1391 The filter has no parameters. The input is not modified. Statistics about
1392 the volume will be printed in the log when the input stream end is reached.
1394 In particular it will show the mean volume (root mean square), maximum
1395 volume (on a per-sample basis), and the beginning of an histogram of the
1396 registered volume values (from the maximum value to a cumulated 1/1000 of
1399 All volumes are in decibels relative to the maximum PCM value.
1401 @subsection Examples
1403 Here is an excerpt of the output:
1405 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1406 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1407 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1408 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1409 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1410 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1411 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1412 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1413 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1419 The mean square energy is approximately -27 dB, or 10^-2.7.
1421 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1423 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1426 In other words, raising the volume by +4 dB does not cause any clipping,
1427 raising it by +5 dB causes clipping for 6 samples, etc.
1429 @c man end AUDIO FILTERS
1431 @chapter Audio Sources
1432 @c man begin AUDIO SOURCES
1434 Below is a description of the currently available audio sources.
1438 Buffer audio frames, and make them available to the filter chain.
1440 This source is mainly intended for a programmatic use, in particular
1441 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1443 It accepts the following named parameters:
1448 Timebase which will be used for timestamps of submitted frames. It must be
1449 either a floating-point number or in @var{numerator}/@var{denominator} form.
1452 The sample rate of the incoming audio buffers.
1455 The sample format of the incoming audio buffers.
1456 Either a sample format name or its corresponging integer representation from
1457 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1459 @item channel_layout
1460 The channel layout of the incoming audio buffers.
1461 Either a channel layout name from channel_layout_map in
1462 @file{libavutil/channel_layout.c} or its corresponding integer representation
1463 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1466 The number of channels of the incoming audio buffers.
1467 If both @var{channels} and @var{channel_layout} are specified, then they
1472 @subsection Examples
1475 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1478 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1479 Since the sample format with name "s16p" corresponds to the number
1480 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1483 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1488 Generate an audio signal specified by an expression.
1490 This source accepts in input one or more expressions (one for each
1491 channel), which are evaluated and used to generate a corresponding
1494 This source accepts the following options:
1498 Set the '|'-separated expressions list for each separate channel. In case the
1499 @option{channel_layout} option is not specified, the selected channel layout
1500 depends on the number of provided expressions.
1502 @item channel_layout, c
1503 Set the channel layout. The number of channels in the specified layout
1504 must be equal to the number of specified expressions.
1507 Set the minimum duration of the sourced audio. See the function
1508 @code{av_parse_time()} for the accepted format.
1509 Note that the resulting duration may be greater than the specified
1510 duration, as the generated audio is always cut at the end of a
1513 If not specified, or the expressed duration is negative, the audio is
1514 supposed to be generated forever.
1517 Set the number of samples per channel per each output frame,
1520 @item sample_rate, s
1521 Specify the sample rate, default to 44100.
1524 Each expression in @var{exprs} can contain the following constants:
1528 number of the evaluated sample, starting from 0
1531 time of the evaluated sample expressed in seconds, starting from 0
1538 @subsection Examples
1548 Generate a sin signal with frequency of 440 Hz, set sample rate to
1551 aevalsrc="sin(440*2*PI*t):s=8000"
1555 Generate a two channels signal, specify the channel layout (Front
1556 Center + Back Center) explicitly:
1558 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
1562 Generate white noise:
1564 aevalsrc="-2+random(0)"
1568 Generate an amplitude modulated signal:
1570 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1574 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1576 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
1583 Null audio source, return unprocessed audio frames. It is mainly useful
1584 as a template and to be employed in analysis / debugging tools, or as
1585 the source for filters which ignore the input data (for example the sox
1588 This source accepts the following options:
1592 @item channel_layout, cl
1594 Specify the channel layout, and can be either an integer or a string
1595 representing a channel layout. The default value of @var{channel_layout}
1598 Check the channel_layout_map definition in
1599 @file{libavutil/channel_layout.c} for the mapping between strings and
1600 channel layout values.
1602 @item sample_rate, r
1603 Specify the sample rate, and defaults to 44100.
1606 Set the number of samples per requested frames.
1610 @subsection Examples
1614 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1616 anullsrc=r=48000:cl=4
1620 Do the same operation with a more obvious syntax:
1622 anullsrc=r=48000:cl=mono
1627 Buffer audio frames, and make them available to the filter chain.
1629 This source is not intended to be part of user-supplied graph descriptions but
1630 for insertion by calling programs through the interface defined in
1631 @file{libavfilter/buffersrc.h}.
1633 It accepts the following named parameters:
1637 Timebase which will be used for timestamps of submitted frames. It must be
1638 either a floating-point number or in @var{numerator}/@var{denominator} form.
1644 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1646 @item channel_layout
1647 Channel layout of the audio data, in the form that can be accepted by
1648 @code{av_get_channel_layout()}.
1651 All the parameters need to be explicitly defined.
1655 Synthesize a voice utterance using the libflite library.
1657 To enable compilation of this filter you need to configure FFmpeg with
1658 @code{--enable-libflite}.
1660 Note that the flite library is not thread-safe.
1662 The filter accepts the following options:
1667 If set to 1, list the names of the available voices and exit
1668 immediately. Default value is 0.
1671 Set the maximum number of samples per frame. Default value is 512.
1674 Set the filename containing the text to speak.
1677 Set the text to speak.
1680 Set the voice to use for the speech synthesis. Default value is
1681 @code{kal}. See also the @var{list_voices} option.
1684 @subsection Examples
1688 Read from file @file{speech.txt}, and synthetize the text using the
1689 standard flite voice:
1691 flite=textfile=speech.txt
1695 Read the specified text selecting the @code{slt} voice:
1697 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1701 Input text to ffmpeg:
1703 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1707 Make @file{ffplay} speak the specified text, using @code{flite} and
1708 the @code{lavfi} device:
1710 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1714 For more information about libflite, check:
1715 @url{http://www.speech.cs.cmu.edu/flite/}
1719 Generate an audio signal made of a sine wave with amplitude 1/8.
1721 The audio signal is bit-exact.
1723 The filter accepts the following options:
1728 Set the carrier frequency. Default is 440 Hz.
1730 @item beep_factor, b
1731 Enable a periodic beep every second with frequency @var{beep_factor} times
1732 the carrier frequency. Default is 0, meaning the beep is disabled.
1734 @item sample_rate, s
1735 Specify the sample rate, default is 44100.
1738 Specify the duration of the generated audio stream.
1740 @item samples_per_frame
1741 Set the number of samples per output frame, default is 1024.
1744 @subsection Examples
1749 Generate a simple 440 Hz sine wave:
1755 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1759 sine=frequency=220:beep_factor=4:duration=5
1764 @c man end AUDIO SOURCES
1766 @chapter Audio Sinks
1767 @c man begin AUDIO SINKS
1769 Below is a description of the currently available audio sinks.
1771 @section abuffersink
1773 Buffer audio frames, and make them available to the end of filter chain.
1775 This sink is mainly intended for programmatic use, in particular
1776 through the interface defined in @file{libavfilter/buffersink.h}.
1778 It requires a pointer to an AVABufferSinkContext structure, which
1779 defines the incoming buffers' formats, to be passed as the opaque
1780 parameter to @code{avfilter_init_filter} for initialization.
1784 Null audio sink, do absolutely nothing with the input audio. It is
1785 mainly useful as a template and to be employed in analysis / debugging
1788 @section abuffersink
1789 This sink is intended for programmatic use. Frames that arrive on this sink can
1790 be retrieved by the calling program using the interface defined in
1791 @file{libavfilter/buffersink.h}.
1793 This filter accepts no parameters.
1795 @c man end AUDIO SINKS
1797 @chapter Video Filters
1798 @c man begin VIDEO FILTERS
1800 When you configure your FFmpeg build, you can disable any of the
1801 existing filters using @code{--disable-filters}.
1802 The configure output will show the video filters included in your
1805 Below is a description of the currently available video filters.
1807 @section alphaextract
1809 Extract the alpha component from the input as a grayscale video. This
1810 is especially useful with the @var{alphamerge} filter.
1814 Add or replace the alpha component of the primary input with the
1815 grayscale value of a second input. This is intended for use with
1816 @var{alphaextract} to allow the transmission or storage of frame
1817 sequences that have alpha in a format that doesn't support an alpha
1820 For example, to reconstruct full frames from a normal YUV-encoded video
1821 and a separate video created with @var{alphaextract}, you might use:
1823 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1826 Since this filter is designed for reconstruction, it operates on frame
1827 sequences without considering timestamps, and terminates when either
1828 input reaches end of stream. This will cause problems if your encoding
1829 pipeline drops frames. If you're trying to apply an image as an
1830 overlay to a video stream, consider the @var{overlay} filter instead.
1834 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1835 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1836 Substation Alpha) subtitles files.
1840 Compute the bounding box for the non-black pixels in the input frame
1843 This filter computes the bounding box containing all the pixels with a
1844 luminance value greater than the minimum allowed value.
1845 The parameters describing the bounding box are printed on the filter
1848 @section blackdetect
1850 Detect video intervals that are (almost) completely black. Can be
1851 useful to detect chapter transitions, commercials, or invalid
1852 recordings. Output lines contains the time for the start, end and
1853 duration of the detected black interval expressed in seconds.
1855 In order to display the output lines, you need to set the loglevel at
1856 least to the AV_LOG_INFO value.
1858 The filter accepts the following options:
1861 @item black_min_duration, d
1862 Set the minimum detected black duration expressed in seconds. It must
1863 be a non-negative floating point number.
1865 Default value is 2.0.
1867 @item picture_black_ratio_th, pic_th
1868 Set the threshold for considering a picture "black".
1869 Express the minimum value for the ratio:
1871 @var{nb_black_pixels} / @var{nb_pixels}
1874 for which a picture is considered black.
1875 Default value is 0.98.
1877 @item pixel_black_th, pix_th
1878 Set the threshold for considering a pixel "black".
1880 The threshold expresses the maximum pixel luminance value for which a
1881 pixel is considered "black". The provided value is scaled according to
1882 the following equation:
1884 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1887 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1888 the input video format, the range is [0-255] for YUV full-range
1889 formats and [16-235] for YUV non full-range formats.
1891 Default value is 0.10.
1894 The following example sets the maximum pixel threshold to the minimum
1895 value, and detects only black intervals of 2 or more seconds:
1897 blackdetect=d=2:pix_th=0.00
1902 Detect frames that are (almost) completely black. Can be useful to
1903 detect chapter transitions or commercials. Output lines consist of
1904 the frame number of the detected frame, the percentage of blackness,
1905 the position in the file if known or -1 and the timestamp in seconds.
1907 In order to display the output lines, you need to set the loglevel at
1908 least to the AV_LOG_INFO value.
1910 The filter accepts parameters as a list of @var{key}=@var{value}
1911 pairs, separated by ":". If the key of the first options is omitted,
1912 the arguments are interpreted according to the syntax
1913 blackframe[=@var{amount}[:@var{threshold}]].
1915 The filter accepts the following options:
1920 The percentage of the pixels that have to be below the threshold, defaults to
1924 Threshold below which a pixel value is considered black, defaults to 32.
1930 Blend two video frames into each other.
1932 It takes two input streams and outputs one stream, the first input is the
1933 "top" layer and second input is "bottom" layer.
1934 Output terminates when shortest input terminates.
1936 A description of the accepted options follows.
1944 Set blend mode for specific pixel component or all pixel components in case
1945 of @var{all_mode}. Default value is @code{normal}.
1947 Available values for component modes are:
1980 Set blend opacity for specific pixel component or all pixel components in case
1981 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1988 Set blend expression for specific pixel component or all pixel components in case
1989 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1991 The expressions can use the following variables:
1995 The sequential number of the filtered frame, starting from @code{0}.
1999 the coordinates of the current sample
2003 the width and height of currently filtered plane
2007 Width and height scale depending on the currently filtered plane. It is the
2008 ratio between the corresponding luma plane number of pixels and the current
2009 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2010 @code{0.5,0.5} for chroma planes.
2013 Time of the current frame, expressed in seconds.
2016 Value of pixel component at current location for first video frame (top layer).
2019 Value of pixel component at current location for second video frame (bottom layer).
2023 @subsection Examples
2027 Apply transition from bottom layer to top layer in first 10 seconds:
2029 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2033 Apply 1x1 checkerboard effect:
2035 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2041 Apply boxblur algorithm to the input video.
2043 The filter accepts parameters as a list of @var{key}=@var{value}
2044 pairs, separated by ":". If the key of the first options is omitted,
2045 the arguments are interpreted according to the syntax
2046 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2048 This filter accepts the following options:
2061 A description of the accepted options follows.
2064 @item luma_radius, lr
2065 @item chroma_radius, cr
2066 @item alpha_radius, ar
2067 Set an expression for the box radius in pixels used for blurring the
2068 corresponding input plane.
2070 The radius value must be a non-negative number, and must not be
2071 greater than the value of the expression @code{min(w,h)/2} for the
2072 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2075 Default value for @option{luma_radius} is "2". If not specified,
2076 @option{chroma_radius} and @option{alpha_radius} default to the
2077 corresponding value set for @option{luma_radius}.
2079 The expressions can contain the following constants:
2082 the input width and height in pixels
2085 the input chroma image width and height in pixels
2088 horizontal and vertical chroma subsample values. For example for the
2089 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2092 @item luma_power, lp
2093 @item chroma_power, cp
2094 @item alpha_power, ap
2095 Specify how many times the boxblur filter is applied to the
2096 corresponding plane.
2098 Default value for @option{luma_power} is 2. If not specified,
2099 @option{chroma_power} and @option{alpha_power} default to the
2100 corresponding value set for @option{luma_power}.
2102 A value of 0 will disable the effect.
2105 @subsection Examples
2109 Apply a boxblur filter with luma, chroma, and alpha radius
2112 boxblur=luma_radius=2:luma_power=1
2117 Set luma radius to 2, alpha and chroma radius to 0:
2119 boxblur=2:1:cr=0:ar=0
2123 Set luma and chroma radius to a fraction of the video dimension:
2125 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2129 @section colormatrix
2131 Convert color matrix.
2133 The filter accepts the following options:
2138 Specify the source and destination color matrix. Both values must be
2141 The accepted values are:
2157 For example to convert from BT.601 to SMPTE-240M, use the command:
2159 colormatrix=bt601:smpte240m
2164 Copy the input source unchanged to the output. Mainly useful for
2169 Crop the input video to given dimensions.
2171 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2172 separated by ':'. If the key of the first options is omitted, the
2173 arguments are interpreted according to the syntax
2174 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2176 A description of the accepted options follows:
2179 Width of the output video. It defaults to @code{iw}.
2180 This expression is evaluated only once during the filter
2184 Height of the output video. It defaults to @code{ih}.
2185 This expression is evaluated only once during the filter
2189 Horizontal position, in the input video, of the left edge of the output video.
2190 It defaults to @code{(in_w-out_w)/2}.
2191 This expression is evaluated per-frame.
2194 Vertical position, in the input video, of the top edge of the output video.
2195 It defaults to @code{(in_h-out_h)/2}.
2196 This expression is evaluated per-frame.
2199 If set to 1 will force the output display aspect ratio
2200 to be the same of the input, by changing the output sample aspect
2201 ratio. It defaults to 0.
2204 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2205 expressions containing the following constants:
2209 the computed values for @var{x} and @var{y}. They are evaluated for
2213 the input width and height
2216 same as @var{in_w} and @var{in_h}
2219 the output (cropped) width and height
2222 same as @var{out_w} and @var{out_h}
2225 same as @var{iw} / @var{ih}
2228 input sample aspect ratio
2231 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2234 horizontal and vertical chroma subsample values. For example for the
2235 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2238 the number of input frame, starting from 0
2241 timestamp expressed in seconds, NAN if the input timestamp is unknown
2245 The expression for @var{out_w} may depend on the value of @var{out_h},
2246 and the expression for @var{out_h} may depend on @var{out_w}, but they
2247 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2248 evaluated after @var{out_w} and @var{out_h}.
2250 The @var{x} and @var{y} parameters specify the expressions for the
2251 position of the top-left corner of the output (non-cropped) area. They
2252 are evaluated for each frame. If the evaluated value is not valid, it
2253 is approximated to the nearest valid value.
2255 The expression for @var{x} may depend on @var{y}, and the expression
2256 for @var{y} may depend on @var{x}.
2258 @subsection Examples
2262 Crop area with size 100x100 at position (12,34).
2267 Using named options, the example above becomes:
2269 crop=w=100:h=100:x=12:y=34
2273 Crop the central input area with size 100x100:
2279 Crop the central input area with size 2/3 of the input video:
2281 crop=2/3*in_w:2/3*in_h
2285 Crop the input video central square:
2292 Delimit the rectangle with the top-left corner placed at position
2293 100:100 and the right-bottom corner corresponding to the right-bottom
2294 corner of the input image:
2296 crop=in_w-100:in_h-100:100:100
2300 Crop 10 pixels from the left and right borders, and 20 pixels from
2301 the top and bottom borders
2303 crop=in_w-2*10:in_h-2*20
2307 Keep only the bottom right quarter of the input image:
2309 crop=in_w/2:in_h/2:in_w/2:in_h/2
2313 Crop height for getting Greek harmony:
2315 crop=in_w:1/PHI*in_w
2319 Appply trembling effect:
2321 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)
2325 Apply erratic camera effect depending on timestamp:
2327 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)"
2331 Set x depending on the value of y:
2333 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2339 Auto-detect crop size.
2341 Calculate necessary cropping parameters and prints the recommended
2342 parameters through the logging system. The detected dimensions
2343 correspond to the non-black area of the input video.
2345 The filter accepts parameters as a list of @var{key}=@var{value}
2346 pairs, separated by ":". If the key of the first options is omitted,
2347 the arguments are interpreted according to the syntax
2348 [@option{limit}[:@option{round}[:@option{reset}]]].
2350 A description of the accepted options follows.
2355 Set higher black value threshold, which can be optionally specified
2356 from nothing (0) to everything (255). An intensity value greater
2357 to the set value is considered non-black. Default value is 24.
2360 Set the value for which the width/height should be divisible by. The
2361 offset is automatically adjusted to center the video. Use 2 to get
2362 only even dimensions (needed for 4:2:2 video). 16 is best when
2363 encoding to most video codecs. Default value is 16.
2366 Set the counter that determines after how many frames cropdetect will
2367 reset the previously detected largest video area and start over to
2368 detect the current optimal crop area. Default value is 0.
2370 This can be useful when channel logos distort the video area. 0
2371 indicates never reset and return the largest area encountered during
2377 Apply color adjustments using curves.
2379 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2380 component (red, green and blue) has its values defined by @var{N} key points
2381 tied from each other using a smooth curve. The x-axis represents the pixel
2382 values from the input frame, and the y-axis the new pixel values to be set for
2385 By default, a component curve is defined by the two points @var{(0;0)} and
2386 @var{(1;1)}. This creates a straight line where each original pixel value is
2387 "adjusted" to its own value, which means no change to the image.
2389 The filter allows you to redefine these two points and add some more. A new
2390 curve (using a natural cubic spline interpolation) will be define to pass
2391 smoothly through all these new coordinates. The new defined points needs to be
2392 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2393 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2394 the vector spaces, the values will be clipped accordingly.
2396 If there is no key point defined in @code{x=0}, the filter will automatically
2397 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2398 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2400 The filter accepts the following options:
2404 Select one of the available color presets. This option can be used in addition
2405 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2406 options takes priority on the preset values.
2407 Available presets are:
2410 @item color_negative
2413 @item increase_contrast
2415 @item linear_contrast
2416 @item medium_contrast
2418 @item strong_contrast
2421 Default is @code{none}.
2423 Set the key points for the red component.
2425 Set the key points for the green component.
2427 Set the key points for the blue component.
2429 Set the key points for all components.
2430 Can be used in addition to the other key points component
2431 options. In this case, the unset component(s) will fallback on this
2432 @option{all} setting.
2435 To avoid some filtergraph syntax conflicts, each key points list need to be
2436 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2438 @subsection Examples
2442 Increase slightly the middle level of blue:
2444 curves=blue='0.5/0.58'
2450 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2452 Here we obtain the following coordinates for each components:
2455 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2457 @code{(0;0) (0.50;0.48) (1;1)}
2459 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2463 The previous example can also be achieved with the associated built-in preset:
2465 curves=preset=vintage
2477 Drop frames that do not differ greatly from the previous frame in
2478 order to reduce frame rate.
2480 The main use of this filter is for very-low-bitrate encoding
2481 (e.g. streaming over dialup modem), but it could in theory be used for
2482 fixing movies that were inverse-telecined incorrectly.
2484 A description of the accepted options follows.
2488 Set the maximum number of consecutive frames which can be dropped (if
2489 positive), or the minimum interval between dropped frames (if
2490 negative). If the value is 0, the frame is dropped unregarding the
2491 number of previous sequentially dropped frames.
2498 Set the dropping threshold values.
2500 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2501 represent actual pixel value differences, so a threshold of 64
2502 corresponds to 1 unit of difference for each pixel, or the same spread
2503 out differently over the block.
2505 A frame is a candidate for dropping if no 8x8 blocks differ by more
2506 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2507 meaning the whole image) differ by more than a threshold of @option{lo}.
2509 Default value for @option{hi} is 64*12, default value for @option{lo} is
2510 64*5, and default value for @option{frac} is 0.33.
2515 Suppress a TV station logo by a simple interpolation of the surrounding
2516 pixels. Just set a rectangle covering the logo and watch it disappear
2517 (and sometimes something even uglier appear - your mileage may vary).
2519 This filter accepts the following options:
2523 Specify the top left corner coordinates of the logo. They must be
2527 Specify the width and height of the logo to clear. They must be
2531 Specify the thickness of the fuzzy edge of the rectangle (added to
2532 @var{w} and @var{h}). The default value is 4.
2535 When set to 1, a green rectangle is drawn on the screen to simplify
2536 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2537 @var{band} is set to 4. The default value is 0.
2541 @subsection Examples
2545 Set a rectangle covering the area with top left corner coordinates 0,0
2546 and size 100x77, setting a band of size 10:
2548 delogo=x=0:y=0:w=100:h=77:band=10
2555 Attempt to fix small changes in horizontal and/or vertical shift. This
2556 filter helps remove camera shake from hand-holding a camera, bumping a
2557 tripod, moving on a vehicle, etc.
2559 The filter accepts the following options:
2567 Specify a rectangular area where to limit the search for motion
2569 If desired the search for motion vectors can be limited to a
2570 rectangular area of the frame defined by its top left corner, width
2571 and height. These parameters have the same meaning as the drawbox
2572 filter which can be used to visualise the position of the bounding
2575 This is useful when simultaneous movement of subjects within the frame
2576 might be confused for camera motion by the motion vector search.
2578 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2579 then the full frame is used. This allows later options to be set
2580 without specifying the bounding box for the motion vector search.
2582 Default - search the whole frame.
2586 Specify the maximum extent of movement in x and y directions in the
2587 range 0-64 pixels. Default 16.
2590 Specify how to generate pixels to fill blanks at the edge of the
2591 frame. Available values are:
2594 Fill zeroes at blank locations
2596 Original image at blank locations
2598 Extruded edge value at blank locations
2600 Mirrored edge at blank locations
2602 Default value is @samp{mirror}.
2605 Specify the blocksize to use for motion search. Range 4-128 pixels,
2609 Specify the contrast threshold for blocks. Only blocks with more than
2610 the specified contrast (difference between darkest and lightest
2611 pixels) will be considered. Range 1-255, default 125.
2614 Specify the search strategy. Available values are:
2617 Set exhaustive search
2619 Set less exhaustive search.
2621 Default value is @samp{exhaustive}.
2624 If set then a detailed log of the motion search is written to the
2628 If set to 1, specify using OpenCL capabilities, only available if
2629 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2635 Draw a colored box on the input image.
2637 This filter accepts the following options:
2641 Specify the top left corner coordinates of the box. Default to 0.
2645 Specify the width and height of the box, if 0 they are interpreted as
2646 the input width and height. Default to 0.
2649 Specify the color of the box to write, it can be the name of a color
2650 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2651 value @code{invert} is used, the box edge color is the same as the
2652 video with inverted luma.
2655 Set the thickness of the box edge. Default value is @code{4}.
2658 @subsection Examples
2662 Draw a black box around the edge of the input image:
2668 Draw a box with color red and an opacity of 50%:
2670 drawbox=10:20:200:60:red@@0.5
2673 The previous example can be specified as:
2675 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2679 Fill the box with pink color:
2681 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2688 Draw text string or text from specified file on top of video using the
2689 libfreetype library.
2691 To enable compilation of this filter you need to configure FFmpeg with
2692 @code{--enable-libfreetype}.
2696 The description of the accepted parameters follows.
2701 Used to draw a box around text using background color.
2702 Value should be either 1 (enable) or 0 (disable).
2703 The default value of @var{box} is 0.
2706 The color to be used for drawing box around text.
2707 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2708 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2709 The default value of @var{boxcolor} is "white".
2712 Set an expression which specifies if the text should be drawn. If the
2713 expression evaluates to 0, the text is not drawn. This is useful for
2714 specifying that the text should be drawn only when specific conditions
2717 Default value is "1".
2719 See below for the list of accepted constants and functions.
2722 Select how the @var{text} is expanded. Can be either @code{none},
2723 @code{strftime} (deprecated) or
2724 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2728 If true, check and fix text coords to avoid clipping.
2731 The color to be used for drawing fonts.
2732 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2733 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2734 The default value of @var{fontcolor} is "black".
2737 The font file to be used for drawing text. Path must be included.
2738 This parameter is mandatory.
2741 The font size to be used for drawing text.
2742 The default value of @var{fontsize} is 16.
2745 Flags to be used for loading the fonts.
2747 The flags map the corresponding flags supported by libfreetype, and are
2748 a combination of the following values:
2755 @item vertical_layout
2756 @item force_autohint
2759 @item ignore_global_advance_width
2761 @item ignore_transform
2768 Default value is "render".
2770 For more information consult the documentation for the FT_LOAD_*
2774 The color to be used for drawing a shadow behind the drawn text. It
2775 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2776 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2777 The default value of @var{shadowcolor} is "black".
2779 @item shadowx, shadowy
2780 The x and y offsets for the text shadow position with respect to the
2781 position of the text. They can be either positive or negative
2782 values. Default value for both is "0".
2785 The size in number of spaces to use for rendering the tab.
2789 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2790 format. It can be used with or without text parameter. @var{timecode_rate}
2791 option must be specified.
2793 @item timecode_rate, rate, r
2794 Set the timecode frame rate (timecode only).
2797 The text string to be drawn. The text must be a sequence of UTF-8
2799 This parameter is mandatory if no file is specified with the parameter
2803 A text file containing text to be drawn. The text must be a sequence
2804 of UTF-8 encoded characters.
2806 This parameter is mandatory if no text string is specified with the
2807 parameter @var{text}.
2809 If both @var{text} and @var{textfile} are specified, an error is thrown.
2812 If set to 1, the @var{textfile} will be reloaded before each frame.
2813 Be sure to update it atomically, or it may be read partially, or even fail.
2816 The expressions which specify the offsets where text will be drawn
2817 within the video frame. They are relative to the top/left border of the
2820 The default value of @var{x} and @var{y} is "0".
2822 See below for the list of accepted constants and functions.
2825 The parameters for @var{x} and @var{y} are expressions containing the
2826 following constants and functions:
2830 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2833 horizontal and vertical chroma subsample values. For example for the
2834 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2837 the height of each text line
2845 @item max_glyph_a, ascent
2846 the maximum distance from the baseline to the highest/upper grid
2847 coordinate used to place a glyph outline point, for all the rendered
2849 It is a positive value, due to the grid's orientation with the Y axis
2852 @item max_glyph_d, descent
2853 the maximum distance from the baseline to the lowest grid coordinate
2854 used to place a glyph outline point, for all the rendered glyphs.
2855 This is a negative value, due to the grid's orientation, with the Y axis
2859 maximum glyph height, that is the maximum height for all the glyphs
2860 contained in the rendered text, it is equivalent to @var{ascent} -
2864 maximum glyph width, that is the maximum width for all the glyphs
2865 contained in the rendered text
2868 the number of input frame, starting from 0
2870 @item rand(min, max)
2871 return a random number included between @var{min} and @var{max}
2874 input sample aspect ratio
2877 timestamp expressed in seconds, NAN if the input timestamp is unknown
2880 the height of the rendered text
2883 the width of the rendered text
2886 the x and y offset coordinates where the text is drawn.
2888 These parameters allow the @var{x} and @var{y} expressions to refer
2889 each other, so you can for example specify @code{y=x/dar}.
2892 If libavfilter was built with @code{--enable-fontconfig}, then
2893 @option{fontfile} can be a fontconfig pattern or omitted.
2895 @anchor{drawtext_expansion}
2896 @subsection Text expansion
2898 If @option{expansion} is set to @code{strftime},
2899 the filter recognizes strftime() sequences in the provided text and
2900 expands them accordingly. Check the documentation of strftime(). This
2901 feature is deprecated.
2903 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2905 If @option{expansion} is set to @code{normal} (which is the default),
2906 the following expansion mechanism is used.
2908 The backslash character '\', followed by any character, always expands to
2909 the second character.
2911 Sequence of the form @code{%@{...@}} are expanded. The text between the
2912 braces is a function name, possibly followed by arguments separated by ':'.
2913 If the arguments contain special characters or delimiters (':' or '@}'),
2914 they should be escaped.
2916 Note that they probably must also be escaped as the value for the
2917 @option{text} option in the filter argument string and as the filter
2918 argument in the filtergraph description, and possibly also for the shell,
2919 that makes up to four levels of escaping; using a text file avoids these
2922 The following functions are available:
2927 The expression evaluation result.
2929 It must take one argument specifying the expression to be evaluated,
2930 which accepts the same constants and functions as the @var{x} and
2931 @var{y} values. Note that not all constants should be used, for
2932 example the text size is not known when evaluating the expression, so
2933 the constants @var{text_w} and @var{text_h} will have an undefined
2937 The time at which the filter is running, expressed in UTC.
2938 It can accept an argument: a strftime() format string.
2941 The time at which the filter is running, expressed in the local time zone.
2942 It can accept an argument: a strftime() format string.
2945 The frame number, starting from 0.
2948 The timestamp of the current frame, in seconds, with microsecond accuracy.
2952 @subsection Examples
2956 Draw "Test Text" with font FreeSerif, using the default values for the
2957 optional parameters.
2960 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2964 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2965 and y=50 (counting from the top-left corner of the screen), text is
2966 yellow with a red box around it. Both the text and the box have an
2970 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2971 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2974 Note that the double quotes are not necessary if spaces are not used
2975 within the parameter list.
2978 Show the text at the center of the video frame:
2980 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2984 Show a text line sliding from right to left in the last row of the video
2985 frame. The file @file{LONG_LINE} is assumed to contain a single line
2988 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2992 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2994 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2998 Draw a single green letter "g", at the center of the input video.
2999 The glyph baseline is placed at half screen height.
3001 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3005 Show text for 1 second every 3 seconds:
3007 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3011 Use fontconfig to set the font. Note that the colons need to be escaped.
3013 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3017 Print the date of a real-time encoding (see strftime(3)):
3019 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3024 For more information about libfreetype, check:
3025 @url{http://www.freetype.org/}.
3027 For more information about fontconfig, check:
3028 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3032 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3034 The filter accepts the following options:
3038 Set low and high threshold values used by the Canny thresholding
3041 The high threshold selects the "strong" edge pixels, which are then
3042 connected through 8-connectivity with the "weak" edge pixels selected
3043 by the low threshold.
3045 @var{low} and @var{high} threshold values must be choosen in the range
3046 [0,1], and @var{low} should be lesser or equal to @var{high}.
3048 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3054 edgedetect=low=0.1:high=0.4
3059 Apply fade-in/out effect to input video.
3061 This filter accepts the following options:
3065 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3067 Default is @code{in}.
3069 @item start_frame, s
3070 Specify the number of the start frame for starting to apply the fade
3071 effect. Default is 0.
3074 The number of frames for which the fade effect has to last. At the end of the
3075 fade-in effect the output video will have the same intensity as the input video,
3076 at the end of the fade-out transition the output video will be completely black.
3080 If set to 1, fade only alpha channel, if one exists on the input.
3084 @subsection Examples
3088 Fade in first 30 frames of video:
3093 The command above is equivalent to:
3099 Fade out last 45 frames of a 200-frame video:
3102 fade=type=out:start_frame=155:nb_frames=45
3106 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3108 fade=in:0:25, fade=out:975:25
3112 Make first 5 frames black, then fade in from frame 5-24:
3118 Fade in alpha over first 25 frames of video:
3120 fade=in:0:25:alpha=1
3126 Extract a single field from an interlaced image using stride
3127 arithmetic to avoid wasting CPU time. The output frames are marked as
3130 The filter accepts the following options:
3134 Specify whether to extract the top (if the value is @code{0} or
3135 @code{top}) or the bottom field (if the value is @code{1} or
3141 Transform the field order of the input video.
3143 This filter accepts the following options:
3148 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3149 for bottom field first.
3152 Default value is @samp{tff}.
3154 Transformation is achieved by shifting the picture content up or down
3155 by one line, and filling the remaining line with appropriate picture content.
3156 This method is consistent with most broadcast field order converters.
3158 If the input video is not flagged as being interlaced, or it is already
3159 flagged as being of the required output field order then this filter does
3160 not alter the incoming video.
3162 This filter is very useful when converting to or from PAL DV material,
3163 which is bottom field first.
3167 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3172 Buffer input images and send them when they are requested.
3174 This filter is mainly useful when auto-inserted by the libavfilter
3177 The filter does not take parameters.
3182 Convert the input video to one of the specified pixel formats.
3183 Libavfilter will try to pick one that is supported for the input to
3186 This filter accepts the following parameters:
3190 A '|'-separated list of pixel format names, for example
3191 "pix_fmts=yuv420p|monow|rgb24".
3195 @subsection Examples
3199 Convert the input video to the format @var{yuv420p}
3201 format=pix_fmts=yuv420p
3204 Convert the input video to any of the formats in the list
3206 format=pix_fmts=yuv420p|yuv444p|yuv410p
3212 Convert the video to specified constant frame rate by duplicating or dropping
3213 frames as necessary.
3215 This filter accepts the following named parameters:
3219 Desired output frame rate. The default is @code{25}.
3224 Possible values are:
3227 zero round towards 0
3231 round towards -infinity
3233 round towards +infinity
3237 The default is @code{near}.
3241 Alternatively, the options can be specified as a flat string:
3242 @var{fps}[:@var{round}].
3244 See also the @ref{setpts} filter.
3248 Select one frame every N-th frame.
3250 This filter accepts the following option:
3253 Select frame after every @code{step} frames.
3254 Allowed values are positive integers higher than 0. Default value is @code{1}.
3260 Apply a frei0r effect to the input video.
3262 To enable compilation of this filter you need to install the frei0r
3263 header and configure FFmpeg with @code{--enable-frei0r}.
3265 This filter accepts the following options:
3270 The name to the frei0r effect to load. If the environment variable
3271 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3272 directories specified by the colon separated list in @env{FREIOR_PATH},
3273 otherwise in the standard frei0r paths, which are in this order:
3274 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3275 @file{/usr/lib/frei0r-1/}.
3278 A '|'-separated list of parameters to pass to the frei0r effect.
3282 A frei0r effect parameter can be a boolean (whose values are specified
3283 with "y" and "n"), a double, a color (specified by the syntax
3284 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3285 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3286 description), a position (specified by the syntax @var{X}/@var{Y},
3287 @var{X} and @var{Y} being float numbers) and a string.
3289 The number and kind of parameters depend on the loaded effect. If an
3290 effect parameter is not specified the default value is set.
3292 @subsection Examples
3296 Apply the distort0r effect, set the first two double parameters:
3298 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3302 Apply the colordistance effect, take a color as first parameter:
3304 frei0r=colordistance:0.2/0.3/0.4
3305 frei0r=colordistance:violet
3306 frei0r=colordistance:0x112233
3310 Apply the perspective effect, specify the top left and top right image
3313 frei0r=perspective:0.2/0.2|0.8/0.2
3317 For more information see:
3318 @url{http://frei0r.dyne.org}
3322 The filter accepts the following options:
3326 the luminance expression
3328 the chrominance blue expression
3330 the chrominance red expression
3332 the alpha expression
3335 If one of the chrominance expression is not defined, it falls back on the other
3336 one. If no alpha expression is specified it will evaluate to opaque value.
3337 If none of chrominance expressions are
3338 specified, they will evaluate the luminance expression.
3340 The expressions can use the following variables and functions:
3344 The sequential number of the filtered frame, starting from @code{0}.
3348 The coordinates of the current sample.
3352 The width and height of the image.
3356 Width and height scale depending on the currently filtered plane. It is the
3357 ratio between the corresponding luma plane number of pixels and the current
3358 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3359 @code{0.5,0.5} for chroma planes.
3362 Time of the current frame, expressed in seconds.
3365 Return the value of the pixel at location (@var{x},@var{y}) of the current
3369 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3373 Return the value of the pixel at location (@var{x},@var{y}) of the
3374 blue-difference chroma plane. Returns 0 if there is no such plane.
3377 Return the value of the pixel at location (@var{x},@var{y}) of the
3378 red-difference chroma plane. Returns 0 if there is no such plane.
3381 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3382 plane. Returns 0 if there is no such plane.
3385 For functions, if @var{x} and @var{y} are outside the area, the value will be
3386 automatically clipped to the closer edge.
3388 @subsection Examples
3392 Flip the image horizontally:
3398 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3399 wavelength of 100 pixels:
3401 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3405 Generate a fancy enigmatic moving light:
3407 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
3413 Fix the banding artifacts that are sometimes introduced into nearly flat
3414 regions by truncation to 8bit color depth.
3415 Interpolate the gradients that should go where the bands are, and
3418 This filter is designed for playback only. Do not use it prior to
3419 lossy compression, because compression tends to lose the dither and
3420 bring back the bands.
3422 This filter accepts the following options:
3427 The maximum amount by which the filter will change any one pixel. Also the
3428 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3429 64, default value is 1.2, out-of-range values will be clipped to the valid
3433 The neighborhood to fit the gradient to. A larger radius makes for smoother
3434 gradients, but also prevents the filter from modifying the pixels near detailed
3435 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3436 will be clipped to the valid range.
3440 Alternatively, the options can be specified as a flat string:
3441 @var{strength}[:@var{radius}]
3443 @subsection Examples
3447 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3453 Specify radius, omitting the strength (which will fall-back to the default
3463 Flip the input video horizontally.
3465 For example to horizontally flip the input video with @command{ffmpeg}:
3467 ffmpeg -i in.avi -vf "hflip" out.avi
3471 This filter applies a global color histogram equalization on a
3474 It can be used to correct video that has a compressed range of pixel
3475 intensities. The filter redistributes the pixel intensities to
3476 equalize their distribution across the intensity range. It may be
3477 viewed as an "automatically adjusting contrast filter". This filter is
3478 useful only for correcting degraded or poorly captured source
3481 The filter accepts the following options:
3485 Determine the amount of equalization to be applied. As the strength
3486 is reduced, the distribution of pixel intensities more-and-more
3487 approaches that of the input frame. The value must be a float number
3488 in the range [0,1] and defaults to 0.200.
3491 Set the maximum intensity that can generated and scale the output
3492 values appropriately. The strength should be set as desired and then
3493 the intensity can be limited if needed to avoid washing-out. The value
3494 must be a float number in the range [0,1] and defaults to 0.210.
3497 Set the antibanding level. If enabled the filter will randomly vary
3498 the luminance of output pixels by a small amount to avoid banding of
3499 the histogram. Possible values are @code{none}, @code{weak} or
3500 @code{strong}. It defaults to @code{none}.
3505 Compute and draw a color distribution histogram for the input video.
3507 The computed histogram is a representation of distribution of color components
3510 The filter accepts the following options:
3516 It accepts the following values:
3519 standard histogram that display color components distribution in an image.
3520 Displays color graph for each color component. Shows distribution
3521 of the Y, U, V, A or G, B, R components, depending on input format,
3522 in current frame. Bellow each graph is color component scale meter.
3525 chroma values in vectorscope, if brighter more such chroma values are
3526 distributed in an image.
3527 Displays chroma values (U/V color placement) in two dimensional graph
3528 (which is called a vectorscope). It can be used to read of the hue and
3529 saturation of the current frame. At a same time it is a histogram.
3530 The whiter a pixel in the vectorscope, the more pixels of the input frame
3531 correspond to that pixel (that is the more pixels have this chroma value).
3532 The V component is displayed on the horizontal (X) axis, with the leftmost
3533 side being V = 0 and the rightmost side being V = 255.
3534 The U component is displayed on the vertical (Y) axis, with the top
3535 representing U = 0 and the bottom representing U = 255.
3537 The position of a white pixel in the graph corresponds to the chroma value
3538 of a pixel of the input clip. So the graph can be used to read of the
3539 hue (color flavor) and the saturation (the dominance of the hue in the color).
3540 As the hue of a color changes, it moves around the square. At the center of
3541 the square, the saturation is zero, which means that the corresponding pixel
3542 has no color. If you increase the amount of a specific color, while leaving
3543 the other colors unchanged, the saturation increases, and you move towards
3544 the edge of the square.
3547 chroma values in vectorscope, similar as @code{color} but actual chroma values
3551 per row/column color component graph. In row mode graph in the left side represents
3552 color component value 0 and right side represents value = 255. In column mode top
3553 side represents color component value = 0 and bottom side represents value = 255.
3555 Default value is @code{levels}.
3558 Set height of level in @code{levels}. Default value is @code{200}.
3559 Allowed range is [50, 2048].
3562 Set height of color scale in @code{levels}. Default value is @code{12}.
3563 Allowed range is [0, 40].
3566 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3567 of same luminance values across input rows/columns are distributed.
3568 Default value is @code{10}. Allowed range is [1, 255].
3571 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3572 Default is @code{row}.
3575 Set display mode for @code{waveform} and @code{levels}.
3576 It accepts the following values:
3579 Display separate graph for the color components side by side in
3580 @code{row} waveform mode or one below other in @code{column} waveform mode
3581 for @code{waveform} histogram mode. For @code{levels} histogram mode
3582 per color component graphs are placed one bellow other.
3584 This display mode in @code{waveform} histogram mode makes it easy to spot
3585 color casts in the highlights and shadows of an image, by comparing the
3586 contours of the top and the bottom of each waveform.
3587 Since whites, grays, and blacks are characterized by
3588 exactly equal amounts of red, green, and blue, neutral areas of the
3589 picture should display three waveforms of roughly equal width/height.
3590 If not, the correction is easy to make by making adjustments to level the
3594 Presents information that's identical to that in the @code{parade}, except
3595 that the graphs representing color components are superimposed directly
3598 This display mode in @code{waveform} histogram mode can make it easier to spot
3599 the relative differences or similarities in overlapping areas of the color
3600 components that are supposed to be identical, such as neutral whites, grays,
3603 Default is @code{parade}.
3606 @subsection Examples
3611 Calculate and draw histogram:
3613 ffplay -i input -vf histogram
3620 High precision/quality 3d denoise filter. This filter aims to reduce
3621 image noise producing smooth images and making still images really
3622 still. It should enhance compressibility.
3624 It accepts the following optional parameters:
3628 a non-negative float number which specifies spatial luma strength,
3631 @item chroma_spatial
3632 a non-negative float number which specifies spatial chroma strength,
3633 defaults to 3.0*@var{luma_spatial}/4.0
3636 a float number which specifies luma temporal strength, defaults to
3637 6.0*@var{luma_spatial}/4.0
3640 a float number which specifies chroma temporal strength, defaults to
3641 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3646 Modify the hue and/or the saturation of the input.
3648 This filter accepts the following options:
3652 Specify the hue angle as a number of degrees. It accepts an expression,
3653 and defaults to "0".
3656 Specify the saturation in the [-10,10] range. It accepts a float number and
3660 Specify the hue angle as a number of radians. It accepts a float
3661 number or an expression, and defaults to "0".
3664 @option{h} and @option{H} are mutually exclusive, and can't be
3665 specified at the same time.
3667 The @option{h}, @option{H} and @option{s} option values are
3668 expressions containing the following constants:
3672 frame count of the input frame starting from 0
3675 presentation timestamp of the input frame expressed in time base units
3678 frame rate of the input video, NAN if the input frame rate is unknown
3681 timestamp expressed in seconds, NAN if the input timestamp is unknown
3684 time base of the input video
3687 @subsection Examples
3691 Set the hue to 90 degrees and the saturation to 1.0:
3697 Same command but expressing the hue in radians:
3703 Rotate hue and make the saturation swing between 0
3704 and 2 over a period of 1 second:
3706 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3710 Apply a 3 seconds saturation fade-in effect starting at 0:
3715 The general fade-in expression can be written as:
3717 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3721 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3723 hue="s=max(0\, min(1\, (8-t)/3))"
3726 The general fade-out expression can be written as:
3728 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3733 @subsection Commands
3735 This filter supports the following command:
3740 Modify the hue and/or the saturation of the input video.
3741 The command accepts the same options and syntax of the corresponding
3744 If the specified expression is not valid, it is kept at its current
3750 Detect video interlacing type.
3752 This filter tries to detect if the input is interlaced or progressive,
3753 top or bottom field first.
3755 The filter accepts the following options:
3759 Set interlacing threshold.
3761 Set progressive threshold.
3766 Deinterleave or interleave fields.
3768 This filter allows to process interlaced images fields without
3769 deinterlacing them. Deinterleaving splits the input frame into 2
3770 fields (so called half pictures). Odd lines are moved to the top
3771 half of the output image, even lines to the bottom half.
3772 You can process (filter) them independently and then re-interleave them.
3774 The filter accepts the following options:
3778 @item chroma_mode, s
3780 Available values for @var{luma_mode}, @var{chroma_mode} and
3781 @var{alpha_mode} are:
3787 @item deinterleave, d
3788 Deinterleave fields, placing one above the other.
3791 Interleave fields. Reverse the effect of deinterleaving.
3793 Default value is @code{none}.
3796 @item chroma_swap, cs
3797 @item alpha_swap, as
3798 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3803 Deinterlace input video by applying Donald Graft's adaptive kernel
3804 deinterling. Work on interlaced parts of a video to produce
3807 The description of the accepted parameters follows.
3811 Set the threshold which affects the filter's tolerance when
3812 determining if a pixel line must be processed. It must be an integer
3813 in the range [0,255] and defaults to 10. A value of 0 will result in
3814 applying the process on every pixels.
3817 Paint pixels exceeding the threshold value to white if set to 1.
3821 Set the fields order. Swap fields if set to 1, leave fields alone if
3825 Enable additional sharpening if set to 1. Default is 0.
3828 Enable twoway sharpening if set to 1. Default is 0.
3831 @subsection Examples
3835 Apply default values:
3837 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3841 Enable additional sharpening:
3847 Paint processed pixels in white:
3853 @section lut, lutrgb, lutyuv
3855 Compute a look-up table for binding each pixel component input value
3856 to an output value, and apply it to input video.
3858 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3859 to an RGB input video.
3861 These filters accept the following options:
3864 set first pixel component expression
3866 set second pixel component expression
3868 set third pixel component expression
3870 set fourth pixel component expression, corresponds to the alpha component
3873 set red component expression
3875 set green component expression
3877 set blue component expression
3879 alpha component expression
3882 set Y/luminance component expression
3884 set U/Cb component expression
3886 set V/Cr component expression
3889 Each of them specifies the expression to use for computing the lookup table for
3890 the corresponding pixel component values.
3892 The exact component associated to each of the @var{c*} options depends on the
3895 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3896 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3898 The expressions can contain the following constants and functions:
3902 the input width and height
3905 input value for the pixel component
3908 the input value clipped in the @var{minval}-@var{maxval} range
3911 maximum value for the pixel component
3914 minimum value for the pixel component
3917 the negated value for the pixel component value clipped in the
3918 @var{minval}-@var{maxval} range , it corresponds to the expression
3919 "maxval-clipval+minval"
3922 the computed value in @var{val} clipped in the
3923 @var{minval}-@var{maxval} range
3925 @item gammaval(gamma)
3926 the computed gamma correction value of the pixel component value
3927 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3929 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3933 All expressions default to "val".
3935 @subsection Examples
3941 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3942 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3945 The above is the same as:
3947 lutrgb="r=negval:g=negval:b=negval"
3948 lutyuv="y=negval:u=negval:v=negval"
3958 Remove chroma components, turns the video into a graytone image:
3960 lutyuv="u=128:v=128"
3964 Apply a luma burning effect:
3970 Remove green and blue components:
3976 Set a constant alpha channel value on input:
3978 format=rgba,lutrgb=a="maxval-minval/2"
3982 Correct luminance gamma by a 0.5 factor:
3984 lutyuv=y=gammaval(0.5)
3988 Discard least significant bits of luma:
3990 lutyuv=y='bitand(val, 128+64+32)'
3996 Apply an MPlayer filter to the input video.
3998 This filter provides a wrapper around most of the filters of
4001 This wrapper is considered experimental. Some of the wrapped filters
4002 may not work properly and we may drop support for them, as they will
4003 be implemented natively into FFmpeg. Thus you should avoid
4004 depending on them when writing portable scripts.
4006 The filters accepts the parameters:
4007 @var{filter_name}[:=]@var{filter_params}
4009 @var{filter_name} is the name of a supported MPlayer filter,
4010 @var{filter_params} is a string containing the parameters accepted by
4013 The list of the currently supported filters follows:
4040 The parameter syntax and behavior for the listed filters are the same
4041 of the corresponding MPlayer filters. For detailed instructions check
4042 the "VIDEO FILTERS" section in the MPlayer manual.
4044 @subsection Examples
4048 Adjust gamma, brightness, contrast:
4054 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4060 This filter accepts an integer in input, if non-zero it negates the
4061 alpha component (if available). The default value in input is 0.
4065 Force libavfilter not to use any of the specified pixel formats for the
4066 input to the next filter.
4068 This filter accepts the following parameters:
4072 A '|'-separated list of pixel format names, for example
4073 "pix_fmts=yuv420p|monow|rgb24".
4077 @subsection Examples
4081 Force libavfilter to use a format different from @var{yuv420p} for the
4082 input to the vflip filter:
4084 noformat=pix_fmts=yuv420p,vflip
4088 Convert the input video to any of the formats not contained in the list:
4090 noformat=yuv420p|yuv444p|yuv410p
4096 Add noise on video input frame.
4098 The filter accepts the following options:
4106 Set noise seed for specific pixel component or all pixel components in case
4107 of @var{all_seed}. Default value is @code{123457}.
4109 @item all_strength, alls
4110 @item c0_strength, c0s
4111 @item c1_strength, c1s
4112 @item c2_strength, c2s
4113 @item c3_strength, c3s
4114 Set noise strength for specific pixel component or all pixel components in case
4115 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4117 @item all_flags, allf
4122 Set pixel component flags or set flags for all components if @var{all_flags}.
4123 Available values for component flags are:
4126 averaged temporal noise (smoother)
4128 mix random noise with a (semi)regular pattern
4130 higher quality (slightly better looking, slightly slower)
4132 temporal noise (noise pattern changes between frames)
4134 uniform noise (gaussian otherwise)
4138 @subsection Examples
4140 Add temporal and uniform noise to input video:
4142 noise=alls=20:allf=t+u
4147 Pass the video source unchanged to the output.
4151 Apply video transform using libopencv.
4153 To enable this filter install libopencv library and headers and
4154 configure FFmpeg with @code{--enable-libopencv}.
4156 This filter accepts the following parameters:
4161 The name of the libopencv filter to apply.
4164 The parameters to pass to the libopencv filter. If not specified the default
4169 Refer to the official libopencv documentation for more precise
4171 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4173 Follows the list of supported libopencv filters.
4178 Dilate an image by using a specific structuring element.
4179 This filter corresponds to the libopencv function @code{cvDilate}.
4181 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4183 @var{struct_el} represents a structuring element, and has the syntax:
4184 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4186 @var{cols} and @var{rows} represent the number of columns and rows of
4187 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4188 point, and @var{shape} the shape for the structuring element, and
4189 can be one of the values "rect", "cross", "ellipse", "custom".
4191 If the value for @var{shape} is "custom", it must be followed by a
4192 string of the form "=@var{filename}". The file with name
4193 @var{filename} is assumed to represent a binary image, with each
4194 printable character corresponding to a bright pixel. When a custom
4195 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4196 or columns and rows of the read file are assumed instead.
4198 The default value for @var{struct_el} is "3x3+0x0/rect".
4200 @var{nb_iterations} specifies the number of times the transform is
4201 applied to the image, and defaults to 1.
4203 Follow some example:
4205 # use the default values
4208 # dilate using a structuring element with a 5x5 cross, iterate two times
4209 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4211 # read the shape from the file diamond.shape, iterate two times
4212 # the file diamond.shape may contain a pattern of characters like this:
4218 # the specified cols and rows are ignored (but not the anchor point coordinates)
4219 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4224 Erode an image by using a specific structuring element.
4225 This filter corresponds to the libopencv function @code{cvErode}.
4227 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4228 with the same syntax and semantics as the @ref{dilate} filter.
4232 Smooth the input video.
4234 The filter takes the following parameters:
4235 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4237 @var{type} is the type of smooth filter to apply, and can be one of
4238 the following values: "blur", "blur_no_scale", "median", "gaussian",
4239 "bilateral". The default value is "gaussian".
4241 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4242 parameters whose meanings depend on smooth type. @var{param1} and
4243 @var{param2} accept integer positive values or 0, @var{param3} and
4244 @var{param4} accept float values.
4246 The default value for @var{param1} is 3, the default value for the
4247 other parameters is 0.
4249 These parameters correspond to the parameters assigned to the
4250 libopencv function @code{cvSmooth}.
4255 Overlay one video on top of another.
4257 It takes two inputs and one output, the first input is the "main"
4258 video on which the second input is overlayed.
4260 This filter accepts the following parameters:
4262 A description of the accepted options follows.
4267 Set the expression for the x and y coordinates of the overlayed video
4268 on the main video. Default value is "0" for both expressions. In case
4269 the expression is invalid, it is set to a huge value (meaning that the
4270 overlay will not be displayed within the output visible area).
4273 Set the expression which enables the overlay. If the evaluation is
4274 different from 0, the overlay is displayed on top of the input
4275 frame. By default it is "1".
4278 Set when the expressions for @option{x}, @option{y}, and
4279 @option{enable} are evaluated.
4281 It accepts the following values:
4284 only evaluate expressions once during the filter initialization or
4285 when a command is processed
4288 evaluate expressions for each incoming frame
4291 Default value is @samp{frame}.
4294 If set to 1, force the output to terminate when the shortest input
4295 terminates. Default value is 0.
4298 Set the format for the output video.
4300 It accepts the following values:
4312 Default value is @samp{yuv420}.
4314 @item rgb @emph{(deprecated)}
4315 If set to 1, force the filter to accept inputs in the RGB
4316 color space. Default value is 0. This option is deprecated, use
4317 @option{format} instead.
4320 The @option{x}, @option{y}, and @option{enable} expressions can
4321 contain the following parameters.
4326 main input width and height
4330 overlay input width and height
4334 the computed values for @var{x} and @var{y}. They are evaluated for
4339 horizontal and vertical chroma subsample values of the output
4340 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4344 the number of input frame, starting from 0
4347 the position in the file of the input frame, NAN if unknown
4350 timestamp expressed in seconds, NAN if the input timestamp is unknown
4353 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4354 when evaluation is done @emph{per frame}, and will evaluate to NAN
4355 when @option{eval} is set to @samp{init}.
4357 Be aware that frames are taken from each input video in timestamp
4358 order, hence, if their initial timestamps differ, it is a a good idea
4359 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4360 have them begin in the same zero timestamp, as it does the example for
4361 the @var{movie} filter.
4363 You can chain together more overlays but you should test the
4364 efficiency of such approach.
4366 @subsection Commands
4368 This filter supports the following command:
4371 Set the @option{x} option expression.
4374 Set the @option{y} option expression.
4377 Set the @option{enable} option expression.
4380 @subsection Examples
4384 Draw the overlay at 10 pixels from the bottom right corner of the main
4387 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4390 Using named options the example above becomes:
4392 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4396 Insert a transparent PNG logo in the bottom left corner of the input,
4397 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4399 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4403 Insert 2 different transparent PNG logos (second logo on bottom
4404 right corner) using the @command{ffmpeg} tool:
4406 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
4410 Add a transparent color layer on top of the main video, @code{WxH}
4411 must specify the size of the main input to the overlay filter:
4413 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4417 Play an original video and a filtered version (here with the deshake
4418 filter) side by side using the @command{ffplay} tool:
4420 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4423 The above command is the same as:
4425 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4429 Make a sliding overlay appearing from the left to the right top part of the
4430 screen starting since time 2:
4432 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4436 Compose output by putting two input videos side to side:
4438 ffmpeg -i left.avi -i right.avi -filter_complex "
4439 nullsrc=size=200x100 [background];
4440 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4441 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4442 [background][left] overlay=shortest=1 [background+left];
4443 [background+left][right] overlay=shortest=1:x=100 [left+right]
4448 Chain several overlays in cascade:
4450 nullsrc=s=200x200 [bg];
4451 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4452 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4453 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4454 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4455 [in3] null, [mid2] overlay=100:100 [out0]
4462 Add paddings to the input image, and place the original input at the
4463 given coordinates @var{x}, @var{y}.
4465 This filter accepts the following parameters:
4470 Specify an expression for the size of the output image with the
4471 paddings added. If the value for @var{width} or @var{height} is 0, the
4472 corresponding input size is used for the output.
4474 The @var{width} expression can reference the value set by the
4475 @var{height} expression, and vice versa.
4477 The default value of @var{width} and @var{height} is 0.
4481 Specify an expression for the offsets where to place the input image
4482 in the padded area with respect to the top/left border of the output
4485 The @var{x} expression can reference the value set by the @var{y}
4486 expression, and vice versa.
4488 The default value of @var{x} and @var{y} is 0.
4491 Specify the color of the padded area, it can be the name of a color
4492 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4494 The default value of @var{color} is "black".
4497 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4498 options are expressions containing the following constants:
4502 the input video width and height
4505 same as @var{in_w} and @var{in_h}
4508 the output width and height, that is the size of the padded area as
4509 specified by the @var{width} and @var{height} expressions
4512 same as @var{out_w} and @var{out_h}
4515 x and y offsets as specified by the @var{x} and @var{y}
4516 expressions, or NAN if not yet specified
4519 same as @var{iw} / @var{ih}
4522 input sample aspect ratio
4525 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4528 horizontal and vertical chroma subsample values. For example for the
4529 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4532 @subsection Examples
4536 Add paddings with color "violet" to the input video. Output video
4537 size is 640x480, the top-left corner of the input video is placed at
4540 pad=640:480:0:40:violet
4543 The example above is equivalent to the following command:
4545 pad=width=640:height=480:x=0:y=40:color=violet
4549 Pad the input to get an output with dimensions increased by 3/2,
4550 and put the input video at the center of the padded area:
4552 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4556 Pad the input to get a squared output with size equal to the maximum
4557 value between the input width and height, and put the input video at
4558 the center of the padded area:
4560 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4564 Pad the input to get a final w/h ratio of 16:9:
4566 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4570 In case of anamorphic video, in order to set the output display aspect
4571 correctly, it is necessary to use @var{sar} in the expression,
4572 according to the relation:
4574 (ih * X / ih) * sar = output_dar
4575 X = output_dar / sar
4578 Thus the previous example needs to be modified to:
4580 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4584 Double output size and put the input video in the bottom-right
4585 corner of the output padded area:
4587 pad="2*iw:2*ih:ow-iw:oh-ih"
4591 @section pixdesctest
4593 Pixel format descriptor test filter, mainly useful for internal
4594 testing. The output video should be equal to the input video.
4598 format=monow, pixdesctest
4601 can be used to test the monowhite pixel format descriptor definition.
4605 Enable the specified chain of postprocessing subfilters using libpostproc. This
4606 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4607 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4608 Each subfilter and some options have a short and a long name that can be used
4609 interchangeably, i.e. dr/dering are the same.
4611 The filters accept the following options:
4615 Set postprocessing subfilters string.
4618 All subfilters share common options to determine their scope:
4622 Honor the quality commands for this subfilter.
4625 Do chrominance filtering, too (default).
4628 Do luminance filtering only (no chrominance).
4631 Do chrominance filtering only (no luminance).
4634 These options can be appended after the subfilter name, separated by a '|'.
4636 Available subfilters are:
4639 @item hb/hdeblock[|difference[|flatness]]
4640 Horizontal deblocking filter
4643 Difference factor where higher values mean more deblocking (default: @code{32}).
4645 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4648 @item vb/vdeblock[|difference[|flatness]]
4649 Vertical deblocking filter
4652 Difference factor where higher values mean more deblocking (default: @code{32}).
4654 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4657 @item ha/hadeblock[|difference[|flatness]]
4658 Accurate horizontal deblocking filter
4661 Difference factor where higher values mean more deblocking (default: @code{32}).
4663 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4666 @item va/vadeblock[|difference[|flatness]]
4667 Accurate vertical deblocking filter
4670 Difference factor where higher values mean more deblocking (default: @code{32}).
4672 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4676 The horizontal and vertical deblocking filters share the difference and
4677 flatness values so you cannot set different horizontal and vertical
4682 Experimental horizontal deblocking filter
4685 Experimental vertical deblocking filter
4690 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4693 larger -> stronger filtering
4695 larger -> stronger filtering
4697 larger -> stronger filtering
4700 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4703 Stretch luminance to @code{0-255}.
4706 @item lb/linblenddeint
4707 Linear blend deinterlacing filter that deinterlaces the given block by
4708 filtering all lines with a @code{(1 2 1)} filter.
4710 @item li/linipoldeint
4711 Linear interpolating deinterlacing filter that deinterlaces the given block by
4712 linearly interpolating every second line.
4714 @item ci/cubicipoldeint
4715 Cubic interpolating deinterlacing filter deinterlaces the given block by
4716 cubically interpolating every second line.
4718 @item md/mediandeint
4719 Median deinterlacing filter that deinterlaces the given block by applying a
4720 median filter to every second line.
4722 @item fd/ffmpegdeint
4723 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4724 second line with a @code{(-1 4 2 4 -1)} filter.
4727 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4728 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4730 @item fq/forceQuant[|quantizer]
4731 Overrides the quantizer table from the input with the constant quantizer you
4739 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4742 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4745 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4748 @subsection Examples
4752 Apply horizontal and vertical deblocking, deringing and automatic
4753 brightness/contrast:
4759 Apply default filters without brightness/contrast correction:
4765 Apply default filters and temporal denoiser:
4767 pp=default/tmpnoise|1|2|3
4771 Apply deblocking on luminance only, and switch vertical deblocking on or off
4772 automatically depending on available CPU time:
4780 Suppress a TV station logo, using an image file to determine which
4781 pixels comprise the logo. It works by filling in the pixels that
4782 comprise the logo with neighboring pixels.
4784 The filters accept the following options:
4788 Set the filter bitmap file, which can be any image format supported by
4789 libavformat. The width and height of the image file must match those of the
4790 video stream being processed.
4793 Pixels in the provided bitmap image with a value of zero are not
4794 considered part of the logo, non-zero pixels are considered part of
4795 the logo. If you use white (255) for the logo and black (0) for the
4796 rest, you will be safe. For making the filter bitmap, it is
4797 recommended to take a screen capture of a black frame with the logo
4798 visible, and then using a threshold filter followed by the erode
4799 filter once or twice.
4801 If needed, little splotches can be fixed manually. Remember that if
4802 logo pixels are not covered, the filter quality will be much
4803 reduced. Marking too many pixels as part of the logo does not hurt as
4804 much, but it will increase the amount of blurring needed to cover over
4805 the image and will destroy more information than necessary, and extra
4806 pixels will slow things down on a large logo.
4810 Scale (resize) the input video, using the libswscale library.
4812 The scale filter forces the output display aspect ratio to be the same
4813 of the input, by changing the output sample aspect ratio.
4815 This filter accepts a list of named options in the form of
4816 @var{key}=@var{value} pairs separated by ":". If the key for the first
4817 two options is not specified, the assumed keys for the first two
4818 values are @code{w} and @code{h}. If the first option has no key and
4819 can be interpreted like a video size specification, it will be used
4820 to set the video size.
4822 A description of the accepted options follows.
4827 default value is @code{iw}. See below
4828 for the list of accepted constants.
4831 Output video height.
4832 default value is @code{ih}.
4833 See below for the list of accepted constants.
4836 Set the interlacing. It accepts the following values:
4840 force interlaced aware scaling
4843 do not apply interlaced scaling
4846 select interlaced aware scaling depending on whether the source frames
4847 are flagged as interlaced or not
4850 Default value is @code{0}.
4853 Set libswscale scaling flags. If not explictly specified the filter
4854 applies a bilinear scaling algorithm.
4857 Set the video size, the value must be a valid abbreviation or in the
4858 form @var{width}x@var{height}.
4861 The values of the @var{w} and @var{h} options are expressions
4862 containing the following constants:
4866 the input width and height
4869 same as @var{in_w} and @var{in_h}
4872 the output (cropped) width and height
4875 same as @var{out_w} and @var{out_h}
4878 same as @var{iw} / @var{ih}
4881 input sample aspect ratio
4884 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4887 horizontal and vertical chroma subsample values. For example for the
4888 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4891 If the input image format is different from the format requested by
4892 the next filter, the scale filter will convert the input to the
4895 If the value for @var{w} or @var{h} is 0, the respective input
4896 size is used for the output.
4898 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4899 respective output size, a value that maintains the aspect ratio of the input
4902 @subsection Examples
4906 Scale the input video to a size of 200x100:
4911 This is equivalent to:
4922 Specify a size abbreviation for the output size:
4927 which can also be written as:
4933 Scale the input to 2x:
4939 The above is the same as:
4945 Scale the input to 2x with forced interlaced scaling:
4947 scale=2*iw:2*ih:interl=1
4951 Scale the input to half size:
4957 Increase the width, and set the height to the same size:
4963 Seek for Greek harmony:
4970 Increase the height, and set the width to 3/2 of the height:
4972 scale=w=3/2*oh:h=3/5*ih
4976 Increase the size, but make the size a multiple of the chroma
4979 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4983 Increase the width to a maximum of 500 pixels, keep the same input
4986 scale=w='min(500\, iw*3/2):h=-1'
4990 @section separatefields
4992 The @code{separatefields} takes a frame-based video input and splits
4993 each frame into its components fields, producing a new half height clip
4994 with twice the frame rate and twice the frame count.
4996 This filter use field-dominance information in frame to decide which
4997 of each pair of fields to place first in the output.
4998 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
5000 @section setdar, setsar
5002 The @code{setdar} filter sets the Display Aspect Ratio for the filter
5005 This is done by changing the specified Sample (aka Pixel) Aspect
5006 Ratio, according to the following equation:
5008 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
5011 Keep in mind that the @code{setdar} filter does not modify the pixel
5012 dimensions of the video frame. Also the display aspect ratio set by
5013 this filter may be changed by later filters in the filterchain,
5014 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5017 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5018 the filter output video.
5020 Note that as a consequence of the application of this filter, the
5021 output display aspect ratio will change according to the equation
5024 Keep in mind that the sample aspect ratio set by the @code{setsar}
5025 filter may be changed by later filters in the filterchain, e.g. if
5026 another "setsar" or a "setdar" filter is applied.
5028 The filters accept the following options:
5031 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
5032 Set the aspect ratio used by the filter.
5034 The parameter can be a floating point number string, an expression, or
5035 a string of the form @var{num}:@var{den}, where @var{num} and
5036 @var{den} are the numerator and denominator of the aspect ratio. If
5037 the parameter is not specified, it is assumed the value "0".
5038 In case the form "@var{num}:@var{den}" the @code{:} character should
5042 Set the maximum integer value to use for expressing numerator and
5043 denominator when reducing the expressed aspect ratio to a rational.
5044 Default value is @code{100}.
5048 @subsection Examples
5053 To change the display aspect ratio to 16:9, specify one of the following:
5061 To change the sample aspect ratio to 10:11, specify:
5067 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5068 1000 in the aspect ratio reduction, use the command:
5070 setdar=ratio=16/9:max=1000
5078 Force field for the output video frame.
5080 The @code{setfield} filter marks the interlace type field for the
5081 output frames. It does not change the input frame, but only sets the
5082 corresponding property, which affects how the frame is treated by
5083 following filters (e.g. @code{fieldorder} or @code{yadif}).
5085 The filter accepts the following options:
5090 Available values are:
5094 Keep the same field property.
5097 Mark the frame as bottom-field-first.
5100 Mark the frame as top-field-first.
5103 Mark the frame as progressive.
5109 Show a line containing various information for each input video frame.
5110 The input video is not modified.
5112 The shown line contains a sequence of key/value pairs of the form
5113 @var{key}:@var{value}.
5115 A description of each shown parameter follows:
5119 sequential number of the input frame, starting from 0
5122 Presentation TimeStamp of the input frame, expressed as a number of
5123 time base units. The time base unit depends on the filter input pad.
5126 Presentation TimeStamp of the input frame, expressed as a number of
5130 position of the frame in the input stream, -1 if this information in
5131 unavailable and/or meaningless (for example in case of synthetic video)
5137 sample aspect ratio of the input frame, expressed in the form
5141 size of the input frame, expressed in the form
5142 @var{width}x@var{height}
5145 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5146 for bottom field first)
5149 1 if the frame is a key frame, 0 otherwise
5152 picture type of the input frame ("I" for an I-frame, "P" for a
5153 P-frame, "B" for a B-frame, "?" for unknown type).
5154 Check also the documentation of the @code{AVPictureType} enum and of
5155 the @code{av_get_picture_type_char} function defined in
5156 @file{libavutil/avutil.h}.
5159 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5161 @item plane_checksum
5162 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5163 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5168 Blur the input video without impacting the outlines.
5170 The filter accepts the following options:
5173 @item luma_radius, lr
5174 Set the luma radius. The option value must be a float number in
5175 the range [0.1,5.0] that specifies the variance of the gaussian filter
5176 used to blur the image (slower if larger). Default value is 1.0.
5178 @item luma_strength, ls
5179 Set the luma strength. The option value must be a float number
5180 in the range [-1.0,1.0] that configures the blurring. A value included
5181 in [0.0,1.0] will blur the image whereas a value included in
5182 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5184 @item luma_threshold, lt
5185 Set the luma threshold used as a coefficient to determine
5186 whether a pixel should be blurred or not. The option value must be an
5187 integer in the range [-30,30]. A value of 0 will filter all the image,
5188 a value included in [0,30] will filter flat areas and a value included
5189 in [-30,0] will filter edges. Default value is 0.
5191 @item chroma_radius, cr
5192 Set the chroma radius. The option value must be a float number in
5193 the range [0.1,5.0] that specifies the variance of the gaussian filter
5194 used to blur the image (slower if larger). Default value is 1.0.
5196 @item chroma_strength, cs
5197 Set the chroma strength. The option value must be a float number
5198 in the range [-1.0,1.0] that configures the blurring. A value included
5199 in [0.0,1.0] will blur the image whereas a value included in
5200 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5202 @item chroma_threshold, ct
5203 Set the chroma threshold used as a coefficient to determine
5204 whether a pixel should be blurred or not. The option value must be an
5205 integer in the range [-30,30]. A value of 0 will filter all the image,
5206 a value included in [0,30] will filter flat areas and a value included
5207 in [-30,0] will filter edges. Default value is 0.
5210 If a chroma option is not explicitly set, the corresponding luma value
5215 Convert between different stereoscopic image formats.
5217 The filters accept the following options:
5221 Set stereoscopic image format of input.
5223 Available values for input image formats are:
5226 side by side parallel (left eye left, right eye right)
5229 side by side crosseye (right eye left, left eye right)
5232 side by side parallel with half width resolution
5233 (left eye left, right eye right)
5236 side by side crosseye with half width resolution
5237 (right eye left, left eye right)
5240 above-below (left eye above, right eye below)
5243 above-below (right eye above, left eye below)
5246 above-below with half height resolution
5247 (left eye above, right eye below)
5250 above-below with half height resolution
5251 (right eye above, left eye below)
5253 Default value is @samp{sbsl}.
5257 Set stereoscopic image format of output.
5259 Available values for output image formats are all the input formats as well as:
5262 anaglyph red/blue gray
5263 (red filter on left eye, blue filter on right eye)
5266 anaglyph red/green gray
5267 (red filter on left eye, green filter on right eye)
5270 anaglyph red/cyan gray
5271 (red filter on left eye, cyan filter on right eye)
5274 anaglyph red/cyan half colored
5275 (red filter on left eye, cyan filter on right eye)
5278 anaglyph red/cyan color
5279 (red filter on left eye, cyan filter on right eye)
5282 anaglyph red/cyan color optimized with the least squares projection of dubois
5283 (red filter on left eye, cyan filter on right eye)
5286 anaglyph green/magenta gray
5287 (green filter on left eye, magenta filter on right eye)
5290 anaglyph green/magenta half colored
5291 (green filter on left eye, magenta filter on right eye)
5294 anaglyph green/magenta colored
5295 (green filter on left eye, magenta filter on right eye)
5298 anaglyph green/magenta color optimized with the least squares projection of dubois
5299 (green filter on left eye, magenta filter on right eye)
5302 anaglyph yellow/blue gray
5303 (yellow filter on left eye, blue filter on right eye)
5306 anaglyph yellow/blue half colored
5307 (yellow filter on left eye, blue filter on right eye)
5310 anaglyph yellow/blue colored
5311 (yellow filter on left eye, blue filter on right eye)
5314 anaglyph yellow/blue color optimized with the least squares projection of dubois
5315 (yellow filter on left eye, blue filter on right eye)
5318 interleaved rows (left eye has top row, right eye starts on next row)
5321 interleaved rows (right eye has top row, left eye starts on next row)
5324 mono output (left eye only)
5327 mono output (right eye only)
5330 Default value is @samp{arcd}.
5336 Draw subtitles on top of input video using the libass library.
5338 To enable compilation of this filter you need to configure FFmpeg with
5339 @code{--enable-libass}. This filter also requires a build with libavcodec and
5340 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5341 Alpha) subtitles format.
5343 The filter accepts the following options:
5347 Set the filename of the subtitle file to read. It must be specified.
5350 Specify the size of the original video, the video for which the ASS file
5351 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5352 necessary to correctly scale the fonts if the aspect ratio has been changed.
5355 Set subtitles input character encoding. @code{subtitles} filter only. Only
5356 useful if not UTF-8.
5359 If the first key is not specified, it is assumed that the first value
5360 specifies the @option{filename}.
5362 For example, to render the file @file{sub.srt} on top of the input
5363 video, use the command:
5368 which is equivalent to:
5370 subtitles=filename=sub.srt
5375 Split input video into several identical outputs.
5377 The filter accepts a single parameter which specifies the number of outputs. If
5378 unspecified, it defaults to 2.
5382 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5384 will create 5 copies of the input video.
5388 [in] split [splitout1][splitout2];
5389 [splitout1] crop=100:100:0:0 [cropout];
5390 [splitout2] pad=200:200:100:100 [padout];
5393 will create two separate outputs from the same input, one cropped and
5398 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5399 Interpolate) pixel art scaling algorithm.
5401 Useful for enlarging pixel art images without reducing sharpness.
5407 Select the most representative frame in a given sequence of consecutive frames.
5409 The filter accepts the following options:
5413 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5414 will pick one of them, and then handle the next batch of @var{n} frames until
5415 the end. Default is @code{100}.
5418 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5419 value will result in a higher memory usage, so a high value is not recommended.
5421 @subsection Examples
5425 Extract one picture each 50 frames:
5431 Complete example of a thumbnail creation with @command{ffmpeg}:
5433 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5439 Tile several successive frames together.
5441 The filter accepts the following options:
5446 Set the grid size (i.e. the number of lines and columns) in the form
5450 Set the maximum number of frames to render in the given area. It must be less
5451 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5452 the area will be used.
5455 Set the outer border margin in pixels.
5458 Set the inner border thickness (i.e. the number of pixels between frames). For
5459 more advanced padding options (such as having different values for the edges),
5460 refer to the pad video filter.
5464 @subsection Examples
5468 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5470 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5472 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5473 duplicating each output frame to accomodate the originally detected frame
5477 Display @code{5} pictures in an area of @code{3x2} frames,
5478 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5479 mixed flat and named options:
5481 tile=3x2:nb_frames=5:padding=7:margin=2
5487 Perform various types of temporal field interlacing.
5489 Frames are counted starting from 1, so the first input frame is
5492 The filter accepts the following options:
5497 Specify the mode of the interlacing. This option can also be specified
5498 as a value alone. See below for a list of values for this option.
5500 Available values are:
5504 Move odd frames into the upper field, even into the lower field,
5505 generating a double height frame at half frame rate.
5508 Only output even frames, odd frames are dropped, generating a frame with
5509 unchanged height at half frame rate.
5512 Only output odd frames, even frames are dropped, generating a frame with
5513 unchanged height at half frame rate.
5516 Expand each frame to full height, but pad alternate lines with black,
5517 generating a frame with double height at the same input frame rate.
5519 @item interleave_top, 4
5520 Interleave the upper field from odd frames with the lower field from
5521 even frames, generating a frame with unchanged height at half frame rate.
5523 @item interleave_bottom, 5
5524 Interleave the lower field from odd frames with the upper field from
5525 even frames, generating a frame with unchanged height at half frame rate.
5527 @item interlacex2, 6
5528 Double frame rate with unchanged height. Frames are inserted each
5529 containing the second temporal field from the previous input frame and
5530 the first temporal field from the next input frame. This mode relies on
5531 the top_field_first flag. Useful for interlaced video displays with no
5532 field synchronisation.
5535 Numeric values are deprecated but are accepted for backward
5536 compatibility reasons.
5538 Default mode is @code{merge}.
5541 Specify flags influencing the filter process.
5543 Available value for @var{flags} is:
5546 @item low_pass_filter, vlfp
5547 Enable vertical low-pass filtering in the filter.
5548 Vertical low-pass filtering is required when creating an interlaced
5549 destination from a progressive source which contains high-frequency
5550 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5553 Vertical low-pass filtering can only be enabled for @option{mode}
5554 @var{interleave_top} and @var{interleave_bottom}.
5561 Transpose rows with columns in the input video and optionally flip it.
5563 This filter accepts the following options:
5568 The direction of the transpose.
5571 @item 0, 4, cclock_flip
5572 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5580 Rotate by 90 degrees clockwise, that is:
5588 Rotate by 90 degrees counterclockwise, that is:
5595 @item 3, 7, clock_flip
5596 Rotate by 90 degrees clockwise and vertically flip, that is:
5604 For values between 4-7, the transposition is only done if the input
5605 video geometry is portrait and not landscape. These values are
5606 deprecated, the @code{passthrough} option should be used instead.
5609 Do not apply the transposition if the input geometry matches the one
5610 specified by the specified value. It accepts the following values:
5613 Always apply transposition.
5615 Preserve portrait geometry (when @var{height} >= @var{width}).
5617 Preserve landscape geometry (when @var{width} >= @var{height}).
5620 Default value is @code{none}.
5623 For example to rotate by 90 degrees clockwise and preserve portrait
5626 transpose=dir=1:passthrough=portrait
5629 The command above can also be specified as:
5631 transpose=1:portrait
5636 Sharpen or blur the input video.
5638 It accepts the following parameters:
5641 @item luma_msize_x, lx
5642 @item chroma_msize_x, cx
5643 Set the luma/chroma matrix horizontal size. It must be an odd integer
5644 between 3 and 63, default value is 5.
5646 @item luma_msize_y, ly
5647 @item chroma_msize_y, cy
5648 Set the luma/chroma matrix vertical size. It must be an odd integer
5649 between 3 and 63, default value is 5.
5651 @item luma_amount, la
5652 @item chroma_amount, ca
5653 Set the luma/chroma effect strength. It can be a float number,
5654 reasonable values lay between -1.5 and 1.5.
5656 Negative values will blur the input video, while positive values will
5657 sharpen it, a value of zero will disable the effect.
5659 Default value is 1.0 for @option{luma_amount}, 0.0 for
5660 @option{chroma_amount}.
5663 All parameters are optional and default to the
5664 equivalent of the string '5:5:1.0:5:5:0.0'.
5666 @subsection Examples
5670 Apply strong luma sharpen effect:
5672 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5676 Apply strong blur of both luma and chroma parameters:
5678 unsharp=7:7:-2:7:7:-2
5684 Flip the input video vertically.
5687 ffmpeg -i in.avi -vf "vflip" out.avi
5692 Deinterlace the input video ("yadif" means "yet another deinterlacing
5695 This filter accepts the following options:
5701 The interlacing mode to adopt, accepts one of the following values:
5705 output 1 frame for each frame
5707 output 1 frame for each field
5708 @item 2, send_frame_nospatial
5709 like @code{send_frame} but skip spatial interlacing check
5710 @item 3, send_field_nospatial
5711 like @code{send_field} but skip spatial interlacing check
5714 Default value is @code{send_frame}.
5717 The picture field parity assumed for the input interlaced video, accepts one of
5718 the following values:
5722 assume top field first
5724 assume bottom field first
5726 enable automatic detection
5729 Default value is @code{auto}.
5730 If interlacing is unknown or decoder does not export this information,
5731 top field first will be assumed.
5734 Specify which frames to deinterlace. Accept one of the following
5739 deinterlace all frames
5741 only deinterlace frames marked as interlaced
5744 Default value is @code{all}.
5747 @c man end VIDEO FILTERS
5749 @chapter Video Sources
5750 @c man begin VIDEO SOURCES
5752 Below is a description of the currently available video sources.
5756 Buffer video frames, and make them available to the filter chain.
5758 This source is mainly intended for a programmatic use, in particular
5759 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5761 It accepts a list of options in the form of @var{key}=@var{value} pairs
5762 separated by ":". A description of the accepted options follows.
5767 Specify the size (width and height) of the buffered video frames.
5776 A string representing the pixel format of the buffered video frames.
5777 It may be a number corresponding to a pixel format, or a pixel format
5781 Specify the timebase assumed by the timestamps of the buffered frames.
5784 Specify the frame rate expected for the video stream.
5786 @item pixel_aspect, sar
5787 Specify the sample aspect ratio assumed by the video frames.
5790 Specify the optional parameters to be used for the scale filter which
5791 is automatically inserted when an input change is detected in the
5792 input size or format.
5797 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
5800 will instruct the source to accept video frames with size 320x240 and
5801 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5802 square pixels (1:1 sample aspect ratio).
5803 Since the pixel format with name "yuv410p" corresponds to the number 6
5804 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5805 this example corresponds to:
5807 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5810 Alternatively, the options can be specified as a flat string, but this
5811 syntax is deprecated:
5813 @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}]
5817 Create a pattern generated by an elementary cellular automaton.
5819 The initial state of the cellular automaton can be defined through the
5820 @option{filename}, and @option{pattern} options. If such options are
5821 not specified an initial state is created randomly.
5823 At each new frame a new row in the video is filled with the result of
5824 the cellular automaton next generation. The behavior when the whole
5825 frame is filled is defined by the @option{scroll} option.
5827 This source accepts the following options:
5831 Read the initial cellular automaton state, i.e. the starting row, from
5833 In the file, each non-whitespace character is considered an alive
5834 cell, a newline will terminate the row, and further characters in the
5835 file will be ignored.
5838 Read the initial cellular automaton state, i.e. the starting row, from
5839 the specified string.
5841 Each non-whitespace character in the string is considered an alive
5842 cell, a newline will terminate the row, and further characters in the
5843 string will be ignored.
5846 Set the video rate, that is the number of frames generated per second.
5849 @item random_fill_ratio, ratio
5850 Set the random fill ratio for the initial cellular automaton row. It
5851 is a floating point number value ranging from 0 to 1, defaults to
5854 This option is ignored when a file or a pattern is specified.
5856 @item random_seed, seed
5857 Set the seed for filling randomly the initial row, must be an integer
5858 included between 0 and UINT32_MAX. If not specified, or if explicitly
5859 set to -1, the filter will try to use a good random seed on a best
5863 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5864 Default value is 110.
5867 Set the size of the output video.
5869 If @option{filename} or @option{pattern} is specified, the size is set
5870 by default to the width of the specified initial state row, and the
5871 height is set to @var{width} * PHI.
5873 If @option{size} is set, it must contain the width of the specified
5874 pattern string, and the specified pattern will be centered in the
5877 If a filename or a pattern string is not specified, the size value
5878 defaults to "320x518" (used for a randomly generated initial state).
5881 If set to 1, scroll the output upward when all the rows in the output
5882 have been already filled. If set to 0, the new generated row will be
5883 written over the top row just after the bottom row is filled.
5886 @item start_full, full
5887 If set to 1, completely fill the output with generated rows before
5888 outputting the first frame.
5889 This is the default behavior, for disabling set the value to 0.
5892 If set to 1, stitch the left and right row edges together.
5893 This is the default behavior, for disabling set the value to 0.
5896 @subsection Examples
5900 Read the initial state from @file{pattern}, and specify an output of
5903 cellauto=f=pattern:s=200x400
5907 Generate a random initial row with a width of 200 cells, with a fill
5910 cellauto=ratio=2/3:s=200x200
5914 Create a pattern generated by rule 18 starting by a single alive cell
5915 centered on an initial row with width 100:
5917 cellauto=p=@@:s=100x400:full=0:rule=18
5921 Specify a more elaborated initial pattern:
5923 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5930 Generate a Mandelbrot set fractal, and progressively zoom towards the
5931 point specified with @var{start_x} and @var{start_y}.
5933 This source accepts the following options:
5938 Set the terminal pts value. Default value is 400.
5941 Set the terminal scale value.
5942 Must be a floating point value. Default value is 0.3.
5945 Set the inner coloring mode, that is the algorithm used to draw the
5946 Mandelbrot fractal internal region.
5948 It shall assume one of the following values:
5953 Show time until convergence.
5955 Set color based on point closest to the origin of the iterations.
5960 Default value is @var{mincol}.
5963 Set the bailout value. Default value is 10.0.
5966 Set the maximum of iterations performed by the rendering
5967 algorithm. Default value is 7189.
5970 Set outer coloring mode.
5971 It shall assume one of following values:
5973 @item iteration_count
5974 Set iteration cound mode.
5975 @item normalized_iteration_count
5976 set normalized iteration count mode.
5978 Default value is @var{normalized_iteration_count}.
5981 Set frame rate, expressed as number of frames per second. Default
5985 Set frame size. Default value is "640x480".
5988 Set the initial scale value. Default value is 3.0.
5991 Set the initial x position. Must be a floating point value between
5992 -100 and 100. Default value is -0.743643887037158704752191506114774.
5995 Set the initial y position. Must be a floating point value between
5996 -100 and 100. Default value is -0.131825904205311970493132056385139.
6001 Generate various test patterns, as generated by the MPlayer test filter.
6003 The size of the generated video is fixed, and is 256x256.
6004 This source is useful in particular for testing encoding features.
6006 This source accepts the following options:
6011 Specify the frame rate of the sourced video, as the number of frames
6012 generated per second. It has to be a string in the format
6013 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6014 number or a valid video frame rate abbreviation. The default value is
6018 Set the video duration of the sourced video. The accepted syntax is:
6023 See also the function @code{av_parse_time()}.
6025 If not specified, or the expressed duration is negative, the video is
6026 supposed to be generated forever.
6030 Set the number or the name of the test to perform. Supported tests are:
6045 Default value is "all", which will cycle through the list of all tests.
6048 For example the following:
6053 will generate a "dc_luma" test pattern.
6057 Provide a frei0r source.
6059 To enable compilation of this filter you need to install the frei0r
6060 header and configure FFmpeg with @code{--enable-frei0r}.
6062 This source accepts the following options:
6067 The size of the video to generate, may be a string of the form
6068 @var{width}x@var{height} or a frame size abbreviation.
6071 Framerate of the generated video, may be a string of the form
6072 @var{num}/@var{den} or a frame rate abbreviation.
6075 The name to the frei0r source to load. For more information regarding frei0r and
6076 how to set the parameters read the section @ref{frei0r} in the description of
6080 A '|'-separated list of parameters to pass to the frei0r source.
6084 For example, to generate a frei0r partik0l source with size 200x200
6085 and frame rate 10 which is overlayed on the overlay filter main input:
6087 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6092 Generate a life pattern.
6094 This source is based on a generalization of John Conway's life game.
6096 The sourced input represents a life grid, each pixel represents a cell
6097 which can be in one of two possible states, alive or dead. Every cell
6098 interacts with its eight neighbours, which are the cells that are
6099 horizontally, vertically, or diagonally adjacent.
6101 At each interaction the grid evolves according to the adopted rule,
6102 which specifies the number of neighbor alive cells which will make a
6103 cell stay alive or born. The @option{rule} option allows to specify
6106 This source accepts the following options:
6110 Set the file from which to read the initial grid state. In the file,
6111 each non-whitespace character is considered an alive cell, and newline
6112 is used to delimit the end of each row.
6114 If this option is not specified, the initial grid is generated
6118 Set the video rate, that is the number of frames generated per second.
6121 @item random_fill_ratio, ratio
6122 Set the random fill ratio for the initial random grid. It is a
6123 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6124 It is ignored when a file is specified.
6126 @item random_seed, seed
6127 Set the seed for filling the initial random grid, must be an integer
6128 included between 0 and UINT32_MAX. If not specified, or if explicitly
6129 set to -1, the filter will try to use a good random seed on a best
6135 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6136 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6137 @var{NS} specifies the number of alive neighbor cells which make a
6138 live cell stay alive, and @var{NB} the number of alive neighbor cells
6139 which make a dead cell to become alive (i.e. to "born").
6140 "s" and "b" can be used in place of "S" and "B", respectively.
6142 Alternatively a rule can be specified by an 18-bits integer. The 9
6143 high order bits are used to encode the next cell state if it is alive
6144 for each number of neighbor alive cells, the low order bits specify
6145 the rule for "borning" new cells. Higher order bits encode for an
6146 higher number of neighbor cells.
6147 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6148 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6150 Default value is "S23/B3", which is the original Conway's game of life
6151 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6152 cells, and will born a new cell if there are three alive cells around
6156 Set the size of the output video.
6158 If @option{filename} is specified, the size is set by default to the
6159 same size of the input file. If @option{size} is set, it must contain
6160 the size specified in the input file, and the initial grid defined in
6161 that file is centered in the larger resulting area.
6163 If a filename is not specified, the size value defaults to "320x240"
6164 (used for a randomly generated initial grid).
6167 If set to 1, stitch the left and right grid edges together, and the
6168 top and bottom edges also. Defaults to 1.
6171 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6172 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6173 value from 0 to 255.
6176 Set the color of living (or new born) cells.
6179 Set the color of dead cells. If @option{mold} is set, this is the first color
6180 used to represent a dead cell.
6183 Set mold color, for definitely dead and moldy cells.
6186 @subsection Examples
6190 Read a grid from @file{pattern}, and center it on a grid of size
6193 life=f=pattern:s=300x300
6197 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6199 life=ratio=2/3:s=200x200
6203 Specify a custom rule for evolving a randomly generated grid:
6209 Full example with slow death effect (mold) using @command{ffplay}:
6211 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6215 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6217 The @code{color} source provides an uniformly colored input.
6219 The @code{nullsrc} source returns unprocessed video frames. It is
6220 mainly useful to be employed in analysis / debugging tools, or as the
6221 source for filters which ignore the input data.
6223 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6224 detecting RGB vs BGR issues. You should see a red, green and blue
6225 stripe from top to bottom.
6227 The @code{smptebars} source generates a color bars pattern, based on
6228 the SMPTE Engineering Guideline EG 1-1990.
6230 The @code{testsrc} source generates a test video pattern, showing a
6231 color pattern, a scrolling gradient and a timestamp. This is mainly
6232 intended for testing purposes.
6234 The sources accept the following options:
6239 Specify the color of the source, only used in the @code{color}
6240 source. It can be the name of a color (case insensitive match) or a
6241 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6242 default value is "black".
6245 Specify the size of the sourced video, it may be a string of the form
6246 @var{width}x@var{height}, or the name of a size abbreviation. The
6247 default value is "320x240".
6250 Specify the frame rate of the sourced video, as the number of frames
6251 generated per second. It has to be a string in the format
6252 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6253 number or a valid video frame rate abbreviation. The default value is
6257 Set the sample aspect ratio of the sourced video.
6260 Set the video duration of the sourced video. The accepted syntax is:
6262 [-]HH[:MM[:SS[.m...]]]
6265 See also the function @code{av_parse_time()}.
6267 If not specified, or the expressed duration is negative, the video is
6268 supposed to be generated forever.
6271 Set the number of decimals to show in the timestamp, only used in the
6272 @code{testsrc} source.
6274 The displayed timestamp value will correspond to the original
6275 timestamp value multiplied by the power of 10 of the specified
6276 value. Default value is 0.
6279 For example the following:
6281 testsrc=duration=5.3:size=qcif:rate=10
6284 will generate a video with a duration of 5.3 seconds, with size
6285 176x144 and a frame rate of 10 frames per second.
6287 The following graph description will generate a red source
6288 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6291 color=c=red@@0.2:s=qcif:r=10
6294 If the input content is to be ignored, @code{nullsrc} can be used. The
6295 following command generates noise in the luminance plane by employing
6296 the @code{geq} filter:
6298 nullsrc=s=256x256, geq=random(1)*255:128:128
6301 @c man end VIDEO SOURCES
6303 @chapter Video Sinks
6304 @c man begin VIDEO SINKS
6306 Below is a description of the currently available video sinks.
6310 Buffer video frames, and make them available to the end of the filter
6313 This sink is mainly intended for a programmatic use, in particular
6314 through the interface defined in @file{libavfilter/buffersink.h}.
6316 It does not require a string parameter in input, but you need to
6317 specify a pointer to a list of supported pixel formats terminated by
6318 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6319 when initializing this sink.
6323 Null video sink, do absolutely nothing with the input video. It is
6324 mainly useful as a template and to be employed in analysis / debugging
6327 @c man end VIDEO SINKS
6329 @chapter Multimedia Filters
6330 @c man begin MULTIMEDIA FILTERS
6332 Below is a description of the currently available multimedia filters.
6334 @section aperms, perms
6336 Set read/write permissions for the output frames.
6338 These filters are mainly aimed at developers to test direct path in the
6339 following filter in the filtergraph.
6341 The filters accept the following options:
6345 Select the permissions mode.
6347 It accepts the following values:
6350 Do nothing. This is the default.
6352 Set all the output frames read-only.
6354 Set all the output frames directly writable.
6356 Make the frame read-only if writable, and writable if read-only.
6358 Set each output frame read-only or writable randomly.
6362 Set the seed for the @var{random} mode, must be an integer included between
6363 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6364 @code{-1}, the filter will try to use a good random seed on a best effort
6368 Note: in case of auto-inserted filter between the permission filter and the
6369 following one, the permission might not be received as expected in that
6370 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6371 perms/aperms filter can avoid this problem.
6374 Add a phasing effect to the input audio.
6376 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6377 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6379 A description of the accepted parameters follows.
6383 Set input gain. Default is 0.4.
6386 Set output gain. Default is 0.74
6389 Set delay in milliseconds. Default is 3.0.
6392 Set decay. Default is 0.4.
6395 Set modulation speed in Hz. Default is 0.5.
6398 Set modulation type. Default is triangular.
6400 It accepts the following values:
6407 @section aselect, select
6408 Select frames to pass in output.
6410 This filter accepts the following options:
6415 An expression, which is evaluated for each input frame. If the expression is
6416 evaluated to a non-zero value, the frame is selected and passed to the output,
6417 otherwise it is discarded.
6421 The expression can contain the following constants:
6425 the sequential number of the filtered frame, starting from 0
6428 the sequential number of the selected frame, starting from 0
6430 @item prev_selected_n
6431 the sequential number of the last selected frame, NAN if undefined
6434 timebase of the input timestamps
6437 the PTS (Presentation TimeStamp) of the filtered video frame,
6438 expressed in @var{TB} units, NAN if undefined
6441 the PTS (Presentation TimeStamp) of the filtered video frame,
6442 expressed in seconds, NAN if undefined
6445 the PTS of the previously filtered video frame, NAN if undefined
6447 @item prev_selected_pts
6448 the PTS of the last previously filtered video frame, NAN if undefined
6450 @item prev_selected_t
6451 the PTS of the last previously selected video frame, NAN if undefined
6454 the PTS of the first video frame in the video, NAN if undefined
6457 the time of the first video frame in the video, NAN if undefined
6459 @item pict_type @emph{(video only)}
6460 the type of the filtered frame, can assume one of the following
6472 @item interlace_type @emph{(video only)}
6473 the frame interlace type, can assume one of the following values:
6476 the frame is progressive (not interlaced)
6478 the frame is top-field-first
6480 the frame is bottom-field-first
6483 @item consumed_sample_n @emph{(audio only)}
6484 the number of selected samples before the current frame
6486 @item samples_n @emph{(audio only)}
6487 the number of samples in the current frame
6489 @item sample_rate @emph{(audio only)}
6490 the input sample rate
6493 1 if the filtered frame is a key-frame, 0 otherwise
6496 the position in the file of the filtered frame, -1 if the information
6497 is not available (e.g. for synthetic video)
6499 @item scene @emph{(video only)}
6500 value between 0 and 1 to indicate a new scene; a low value reflects a low
6501 probability for the current frame to introduce a new scene, while a higher
6502 value means the current frame is more likely to be one (see the example below)
6506 The default value of the select expression is "1".
6508 @subsection Examples
6512 Select all frames in input:
6517 The example above is the same as:
6529 Select only I-frames:
6531 select='eq(pict_type\,I)'
6535 Select one frame every 100:
6537 select='not(mod(n\,100))'
6541 Select only frames contained in the 10-20 time interval:
6543 select='gte(t\,10)*lte(t\,20)'
6547 Select only I frames contained in the 10-20 time interval:
6549 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6553 Select frames with a minimum distance of 10 seconds:
6555 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6559 Use aselect to select only audio frames with samples number > 100:
6561 aselect='gt(samples_n\,100)'
6565 Create a mosaic of the first scenes:
6567 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6570 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6574 @section asendcmd, sendcmd
6576 Send commands to filters in the filtergraph.
6578 These filters read commands to be sent to other filters in the
6581 @code{asendcmd} must be inserted between two audio filters,
6582 @code{sendcmd} must be inserted between two video filters, but apart
6583 from that they act the same way.
6585 The specification of commands can be provided in the filter arguments
6586 with the @var{commands} option, or in a file specified by the
6587 @var{filename} option.
6589 These filters accept the following options:
6592 Set the commands to be read and sent to the other filters.
6594 Set the filename of the commands to be read and sent to the other
6598 @subsection Commands syntax
6600 A commands description consists of a sequence of interval
6601 specifications, comprising a list of commands to be executed when a
6602 particular event related to that interval occurs. The occurring event
6603 is typically the current frame time entering or leaving a given time
6606 An interval is specified by the following syntax:
6608 @var{START}[-@var{END}] @var{COMMANDS};
6611 The time interval is specified by the @var{START} and @var{END} times.
6612 @var{END} is optional and defaults to the maximum time.
6614 The current frame time is considered within the specified interval if
6615 it is included in the interval [@var{START}, @var{END}), that is when
6616 the time is greater or equal to @var{START} and is lesser than
6619 @var{COMMANDS} consists of a sequence of one or more command
6620 specifications, separated by ",", relating to that interval. The
6621 syntax of a command specification is given by:
6623 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6626 @var{FLAGS} is optional and specifies the type of events relating to
6627 the time interval which enable sending the specified command, and must
6628 be a non-null sequence of identifier flags separated by "+" or "|" and
6629 enclosed between "[" and "]".
6631 The following flags are recognized:
6634 The command is sent when the current frame timestamp enters the
6635 specified interval. In other words, the command is sent when the
6636 previous frame timestamp was not in the given interval, and the
6640 The command is sent when the current frame timestamp leaves the
6641 specified interval. In other words, the command is sent when the
6642 previous frame timestamp was in the given interval, and the
6646 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6649 @var{TARGET} specifies the target of the command, usually the name of
6650 the filter class or a specific filter instance name.
6652 @var{COMMAND} specifies the name of the command for the target filter.
6654 @var{ARG} is optional and specifies the optional list of argument for
6655 the given @var{COMMAND}.
6657 Between one interval specification and another, whitespaces, or
6658 sequences of characters starting with @code{#} until the end of line,
6659 are ignored and can be used to annotate comments.
6661 A simplified BNF description of the commands specification syntax
6664 @var{COMMAND_FLAG} ::= "enter" | "leave"
6665 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6666 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6667 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6668 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6669 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6672 @subsection Examples
6676 Specify audio tempo change at second 4:
6678 asendcmd=c='4.0 atempo tempo 1.5',atempo
6682 Specify a list of drawtext and hue commands in a file.
6684 # show text in the interval 5-10
6685 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6686 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6688 # desaturate the image in the interval 15-20
6689 15.0-20.0 [enter] hue s 0,
6690 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6692 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6694 # apply an exponential saturation fade-out effect, starting from time 25
6695 25 [enter] hue s exp(25-t)
6698 A filtergraph allowing to read and process the above command list
6699 stored in a file @file{test.cmd}, can be specified with:
6701 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6706 @section asetpts, setpts
6708 Change the PTS (presentation timestamp) of the input frames.
6710 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6712 This filter accepts the following options:
6717 The expression which is evaluated for each frame to construct its timestamp.
6721 The expression is evaluated through the eval API and can contain the following
6726 frame rate, only defined for constant frame-rate video
6729 the presentation timestamp in input
6732 the count of the input frame, starting from 0.
6734 @item NB_CONSUMED_SAMPLES
6735 the number of consumed samples, not including the current frame (only
6739 the number of samples in the current frame (only audio)
6745 the PTS of the first frame
6748 the time in seconds of the first frame
6751 tell if the current frame is interlaced
6754 the time in seconds of the current frame
6760 original position in the file of the frame, or undefined if undefined
6761 for the current frame
6767 previous input time in seconds
6773 previous output time in seconds
6776 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6780 wallclock (RTC) time at the start of the movie in microseconds
6783 @subsection Examples
6787 Start counting PTS from zero
6793 Apply fast motion effect:
6799 Apply slow motion effect:
6805 Set fixed rate of 25 frames per second:
6811 Set fixed rate 25 fps with some jitter:
6813 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6817 Apply an offset of 10 seconds to the input PTS:
6823 Generate timestamps from a "live source" and rebase onto the current timebase:
6825 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6831 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6832 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6833 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6834 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6836 The filter also has a video output (see the @var{video} option) with a real
6837 time graph to observe the loudness evolution. The graphic contains the logged
6838 message mentioned above, so it is not printed anymore when this option is set,
6839 unless the verbose logging is set. The main graphing area contains the
6840 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6841 the momentary loudness (400 milliseconds).
6843 More information about the Loudness Recommendation EBU R128 on
6844 @url{http://tech.ebu.ch/loudness}.
6846 The filter accepts the following options:
6851 Activate the video output. The audio stream is passed unchanged whether this
6852 option is set or no. The video stream will be the first output stream if
6853 activated. Default is @code{0}.
6856 Set the video size. This option is for video only. Default and minimum
6857 resolution is @code{640x480}.
6860 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6861 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6862 other integer value between this range is allowed.
6865 Set metadata injection. If set to @code{1}, the audio input will be segmented
6866 into 100ms output frames, each of them containing various loudness information
6867 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6869 Default is @code{0}.
6872 Force the frame logging level.
6874 Available values are:
6877 information logging level
6879 verbose logging level
6882 By default, the logging level is set to @var{info}. If the @option{video} or
6883 the @option{metadata} options are set, it switches to @var{verbose}.
6886 @subsection Examples
6890 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6892 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6896 Run an analysis with @command{ffmpeg}:
6898 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6902 @section settb, asettb
6904 Set the timebase to use for the output frames timestamps.
6905 It is mainly useful for testing timebase configuration.
6907 This filter accepts the following options:
6912 The expression which is evaluated into the output timebase.
6916 The value for @option{tb} is an arithmetic expression representing a
6917 rational. The expression can contain the constants "AVTB" (the default
6918 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6919 audio only). Default value is "intb".
6921 @subsection Examples
6925 Set the timebase to 1/25:
6931 Set the timebase to 1/10:
6937 Set the timebase to 1001/1000:
6943 Set the timebase to 2*intb:
6949 Set the default timebase value:
6957 Concatenate audio and video streams, joining them together one after the
6960 The filter works on segments of synchronized video and audio streams. All
6961 segments must have the same number of streams of each type, and that will
6962 also be the number of streams at output.
6964 The filter accepts the following options:
6969 Set the number of segments. Default is 2.
6972 Set the number of output video streams, that is also the number of video
6973 streams in each segment. Default is 1.
6976 Set the number of output audio streams, that is also the number of video
6977 streams in each segment. Default is 0.
6980 Activate unsafe mode: do not fail if segments have a different format.
6984 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6985 @var{a} audio outputs.
6987 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6988 segment, in the same order as the outputs, then the inputs for the second
6991 Related streams do not always have exactly the same duration, for various
6992 reasons including codec frame size or sloppy authoring. For that reason,
6993 related synchronized streams (e.g. a video and its audio track) should be
6994 concatenated at once. The concat filter will use the duration of the longest
6995 stream in each segment (except the last one), and if necessary pad shorter
6996 audio streams with silence.
6998 For this filter to work correctly, all segments must start at timestamp 0.
7000 All corresponding streams must have the same parameters in all segments; the
7001 filtering system will automatically select a common pixel format for video
7002 streams, and a common sample format, sample rate and channel layout for
7003 audio streams, but other settings, such as resolution, must be converted
7004 explicitly by the user.
7006 Different frame rates are acceptable but will result in variable frame rate
7007 at output; be sure to configure the output file to handle it.
7009 @subsection Examples
7013 Concatenate an opening, an episode and an ending, all in bilingual version
7014 (video in stream 0, audio in streams 1 and 2):
7016 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
7017 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7018 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7019 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7023 Concatenate two parts, handling audio and video separately, using the
7024 (a)movie sources, and adjusting the resolution:
7026 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7027 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7028 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7030 Note that a desync will happen at the stitch if the audio and video streams
7031 do not have exactly the same duration in the first file.
7035 @section showspectrum
7037 Convert input audio to a video output, representing the audio frequency
7040 The filter accepts the following options:
7044 Specify the video size for the output. Default value is @code{640x512}.
7047 Specify if the spectrum should slide along the window. Default value is
7051 Specify display mode.
7053 It accepts the following values:
7056 all channels are displayed in the same row
7058 all channels are displayed in separate rows
7061 Default value is @samp{combined}.
7064 Specify display color mode.
7066 It accepts the following values:
7069 each channel is displayed in a separate color
7071 each channel is is displayed using the same color scheme
7074 Default value is @samp{channel}.
7077 Specify scale used for calculating intensity color values.
7079 It accepts the following values:
7084 square root, default
7091 Default value is @samp{sqrt}.
7094 Set saturation modifier for displayed colors. Negative values provide
7095 alternative color scheme. @code{0} is no saturation at all.
7096 Saturation must be in [-10.0, 10.0] range.
7097 Default value is @code{1}.
7100 The usage is very similar to the showwaves filter; see the examples in that
7103 @subsection Examples
7107 Large window with logarithmic color scaling:
7109 showspectrum=s=1280x480:scale=log
7113 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7115 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7116 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7122 Convert input audio to a video output, representing the samples waves.
7124 The filter accepts the following options:
7128 Specify the video size for the output. Default value is "600x240".
7133 Available values are:
7136 Draw a point for each sample.
7139 Draw a vertical line for each sample.
7142 Default value is @code{point}.
7145 Set the number of samples which are printed on the same column. A
7146 larger value will decrease the frame rate. Must be a positive
7147 integer. This option can be set only if the value for @var{rate}
7148 is not explicitly specified.
7151 Set the (approximate) output frame rate. This is done by setting the
7152 option @var{n}. Default value is "25".
7156 @subsection Examples
7160 Output the input file audio and the corresponding video representation
7163 amovie=a.mp3,asplit[out0],showwaves[out1]
7167 Create a synthetic signal and show it with showwaves, forcing a
7168 frame rate of 30 frames per second:
7170 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7174 @c man end MULTIMEDIA FILTERS
7176 @chapter Multimedia Sources
7177 @c man begin MULTIMEDIA SOURCES
7179 Below is a description of the currently available multimedia sources.
7183 This is the same as @ref{movie} source, except it selects an audio
7189 Read audio and/or video stream(s) from a movie container.
7191 This filter accepts the following options:
7195 The name of the resource to read (not necessarily a file but also a device or a
7196 stream accessed through some protocol).
7198 @item format_name, f
7199 Specifies the format assumed for the movie to read, and can be either
7200 the name of a container or an input device. If not specified the
7201 format is guessed from @var{movie_name} or by probing.
7203 @item seek_point, sp
7204 Specifies the seek point in seconds, the frames will be output
7205 starting from this seek point, the parameter is evaluated with
7206 @code{av_strtod} so the numerical value may be suffixed by an IS
7207 postfix. Default value is "0".
7210 Specifies the streams to read. Several streams can be specified,
7211 separated by "+". The source will then have as many outputs, in the
7212 same order. The syntax is explained in the ``Stream specifiers''
7213 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7214 respectively the default (best suited) video and audio stream. Default
7215 is "dv", or "da" if the filter is called as "amovie".
7217 @item stream_index, si
7218 Specifies the index of the video stream to read. If the value is -1,
7219 the best suited video stream will be automatically selected. Default
7220 value is "-1". Deprecated. If the filter is called "amovie", it will select
7221 audio instead of video.
7224 Specifies how many times to read the stream in sequence.
7225 If the value is less than 1, the stream will be read again and again.
7226 Default value is "1".
7228 Note that when the movie is looped the source timestamps are not
7229 changed, so it will generate non monotonically increasing timestamps.
7232 This filter allows to overlay a second video on top of main input of
7233 a filtergraph as shown in this graph:
7235 input -----------> deltapts0 --> overlay --> output
7238 movie --> scale--> deltapts1 -------+
7241 @subsection Examples
7245 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7246 on top of the input labelled as "in":
7248 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7249 [in] setpts=PTS-STARTPTS [main];
7250 [main][over] overlay=16:16 [out]
7254 Read from a video4linux2 device, and overlay it on top of the input
7257 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7258 [in] setpts=PTS-STARTPTS [main];
7259 [main][over] overlay=16:16 [out]
7263 Read the first video stream and the audio stream with id 0x81 from
7264 dvd.vob; the video is connected to the pad named "video" and the audio is
7265 connected to the pad named "audio":
7267 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7271 @c man end MULTIMEDIA SOURCES