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/avfilter.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 the following options:
331 Set method to specify band-width of filter.
344 Specify the band-width of a filter in width_type units.
349 Apply a high-pass filter with 3dB point frequency.
350 The filter can be either single-pole, or double-pole (the default).
351 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
353 The filter accepts the following options:
357 Set frequency in Hz. Default is 3000.
360 Set number of poles. Default is 2.
363 Set method to specify band-width of filter.
376 Specify the band-width of a filter in width_type units.
377 Applies only to double-pole filter.
378 The default is 0.707q and gives a Butterworth response.
383 Apply a low-pass filter with 3dB point frequency.
384 The filter can be either single-pole or double-pole (the default).
385 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
387 The filter accepts the following options:
391 Set frequency in Hz. Default is 500.
394 Set number of poles. Default is 2.
397 Set method to specify band-width of filter.
410 Specify the band-width of a filter in width_type units.
411 Applies only to double-pole filter.
412 The default is 0.707q and gives a Butterworth response.
417 Boost or cut the bass (lower) frequencies of the audio using a two-pole
418 shelving filter with a response similar to that of a standard
419 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
421 The filter accepts the following options:
425 Give the gain at 0 Hz. Its useful range is about -20
426 (for a large cut) to +20 (for a large boost).
427 Beware of clipping when using a positive gain.
430 Set the filter's central frequency and so can be used
431 to extend or reduce the frequency range to be boosted or cut.
432 The default value is @code{100} Hz.
435 Set method to specify band-width of filter.
448 Determine how steep is the filter's shelf transition.
453 Apply telecine process to the video.
455 This filter accepts the following options:
464 The default value is @code{top}.
468 A string of numbers representing the pulldown pattern you wish to apply.
469 The default value is @code{23}.
473 Some typical patterns:
478 24p: 2332 (preferred)
485 24p: 222222222223 ("Euro pulldown")
492 Boost or cut treble (upper) frequencies of the audio using a two-pole
493 shelving filter with a response similar to that of a standard
494 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
496 The filter accepts the following options:
500 Give the gain at whichever is the lower of ~22 kHz and the
501 Nyquist frequency. Its useful range is about -20 (for a large cut)
502 to +20 (for a large boost). Beware of clipping when using a positive gain.
505 Set the filter's central frequency and so can be used
506 to extend or reduce the frequency range to be boosted or cut.
507 The default value is @code{3000} Hz.
510 Set method to specify band-width of filter.
523 Determine how steep is the filter's shelf transition.
528 Apply a two-pole Butterworth band-pass filter with central
529 frequency @var{frequency}, and (3dB-point) band-width width.
530 The @var{csg} option selects a constant skirt gain (peak gain = Q)
531 instead of the default: constant 0dB peak gain.
532 The filter roll off at 6dB per octave (20dB per decade).
534 The filter accepts the following options:
538 Set the filter's central frequency. Default is @code{3000}.
541 Constant skirt gain if set to 1. Defaults to 0.
544 Set method to specify band-width of filter.
557 Specify the band-width of a filter in width_type units.
562 Apply a two-pole Butterworth band-reject filter with central
563 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
564 The filter roll off at 6dB per octave (20dB per decade).
566 The filter accepts the following options:
570 Set the filter's central frequency. Default is @code{3000}.
573 Set method to specify band-width of filter.
586 Specify the band-width of a filter in width_type units.
591 Apply a biquad IIR filter with the given coefficients.
592 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
593 are the numerator and denominator coefficients respectively.
597 Apply a two-pole peaking equalisation (EQ) filter. With this
598 filter, the signal-level at and around a selected frequency can
599 be increased or decreased, whilst (unlike bandpass and bandreject
600 filters) that at all other frequencies is unchanged.
602 In order to produce complex equalisation curves, this filter can
603 be given several times, each with a different central frequency.
605 The filter accepts the following options:
609 Set the filter's central frequency in Hz.
612 Set method to specify band-width of filter.
625 Specify the band-width of a filter in width_type units.
628 Set the required gain or attenuation in dB.
629 Beware of clipping when using a positive gain.
634 Apply fade-in/out effect to input audio.
636 A description of the accepted parameters follows.
640 Specify the effect type, can be either @code{in} for fade-in, or
641 @code{out} for a fade-out effect. Default is @code{in}.
643 @item start_sample, ss
644 Specify the number of the start sample for starting to apply the fade
645 effect. Default is 0.
648 Specify the number of samples for which the fade effect has to last. At
649 the end of the fade-in effect the output audio will have the same
650 volume as the input audio, at the end of the fade-out transition
651 the output audio will be silence. Default is 44100.
654 Specify time in seconds for starting to apply the fade
655 effect. Default is 0.
656 If set this option is used instead of @var{start_sample} one.
659 Specify the number of seconds for which the fade effect has to last. At
660 the end of the fade-in effect the output audio will have the same
661 volume as the input audio, at the end of the fade-out transition
662 the output audio will be silence. Default is 0.
663 If set this option is used instead of @var{nb_samples} one.
666 Set curve for fade transition.
668 It accepts the following values:
671 select triangular, linear slope (default)
673 select quarter of sine wave
675 select half of sine wave
677 select exponential sine wave
681 select inverted parabola
697 Fade in first 15 seconds of audio:
703 Fade out last 25 seconds of a 900 seconds audio:
705 afade=t=out:ss=875:d=25
712 Set output format constraints for the input audio. The framework will
713 negotiate the most appropriate format to minimize conversions.
715 The filter accepts the following named parameters:
719 A '|'-separated list of requested sample formats.
722 A '|'-separated list of requested sample rates.
724 @item channel_layouts
725 A '|'-separated list of requested channel layouts.
729 If a parameter is omitted, all values are allowed.
731 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
733 aformat=sample_fmts=u8|s16:channel_layouts=stereo
738 Merge two or more audio streams into a single multi-channel stream.
740 The filter accepts the following options:
745 Set the number of inputs. Default is 2.
749 If the channel layouts of the inputs are disjoint, and therefore compatible,
750 the channel layout of the output will be set accordingly and the channels
751 will be reordered as necessary. If the channel layouts of the inputs are not
752 disjoint, the output will have all the channels of the first input then all
753 the channels of the second input, in that order, and the channel layout of
754 the output will be the default value corresponding to the total number of
757 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
758 is FC+BL+BR, then the output will be in 5.1, with the channels in the
759 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
760 first input, b1 is the first channel of the second input).
762 On the other hand, if both input are in stereo, the output channels will be
763 in the default order: a1, a2, b1, b2, and the channel layout will be
764 arbitrarily set to 4.0, which may or may not be the expected value.
766 All inputs must have the same sample rate, and format.
768 If inputs do not have the same duration, the output will stop with the
775 Merge two mono files into a stereo stream:
777 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
781 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
783 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
789 Mixes multiple audio inputs into a single output.
793 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
795 will mix 3 input audio streams to a single output with the same duration as the
796 first input and a dropout transition time of 3 seconds.
798 The filter accepts the following named parameters:
802 Number of inputs. If unspecified, it defaults to 2.
805 How to determine the end-of-stream.
809 Duration of longest input. (default)
812 Duration of shortest input.
815 Duration of first input.
819 @item dropout_transition
820 Transition time, in seconds, for volume renormalization when an input
821 stream ends. The default value is 2 seconds.
827 Pass the audio source unchanged to the output.
831 Pad the end of a audio stream with silence, this can be used together with
832 -shortest to extend audio streams to the same length as the video stream.
837 Resample the input audio to the specified parameters, using the
838 libswresample library. If none are specified then the filter will
839 automatically convert between its input and output.
841 This filter is also able to stretch/squeeze the audio data to make it match
842 the timestamps or to inject silence / cut out audio to make it match the
843 timestamps, do a combination of both or do neither.
845 The filter accepts the syntax
846 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
847 expresses a sample rate and @var{resampler_options} is a list of
848 @var{key}=@var{value} pairs, separated by ":". See the
849 ffmpeg-resampler manual for the complete list of supported options.
855 Resample the input audio to 44100Hz:
861 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
862 samples per second compensation:
868 @section asetnsamples
870 Set the number of samples per each output audio frame.
872 The last output packet may contain a different number of samples, as
873 the filter will flush all the remaining samples when the input audio
876 The filter accepts the following options:
880 @item nb_out_samples, n
881 Set the number of frames per each output audio frame. The number is
882 intended as the number of samples @emph{per each channel}.
883 Default value is 1024.
886 If set to 1, the filter will pad the last audio frame with zeroes, so
887 that the last frame will contain the same number of samples as the
888 previous ones. Default value is 1.
891 For example, to set the number of per-frame samples to 1234 and
892 disable padding for the last frame, use:
894 asetnsamples=n=1234:p=0
899 Show a line containing various information for each input audio frame.
900 The input audio is not modified.
902 The shown line contains a sequence of key/value pairs of the form
903 @var{key}:@var{value}.
905 A description of each shown parameter follows:
909 sequential number of the input frame, starting from 0
912 Presentation timestamp of the input frame, in time base units; the time base
913 depends on the filter input pad, and is usually 1/@var{sample_rate}.
916 presentation timestamp of the input frame in seconds
919 position of the frame in the input stream, -1 if this information in
920 unavailable and/or meaningless (for example in case of synthetic audio)
929 sample rate for the audio frame
932 number of samples (per channel) in the frame
935 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
936 the data is treated as if all the planes were concatenated.
938 @item plane_checksums
939 A list of Adler-32 checksums for each data plane.
944 Split input audio into several identical outputs.
946 The filter accepts a single parameter which specifies the number of outputs. If
947 unspecified, it defaults to 2.
951 [in] asplit [out0][out1]
954 will create two separate outputs from the same input.
956 To create 3 or more outputs, you need to specify the number of
959 [in] asplit=3 [out0][out1][out2]
963 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
965 will create 5 copies of the input audio.
970 Forward two audio streams and control the order the buffers are forwarded.
972 The filter accepts the following options:
976 Set the expression deciding which stream should be
977 forwarded next: if the result is negative, the first stream is forwarded; if
978 the result is positive or zero, the second stream is forwarded. It can use
979 the following variables:
983 number of buffers forwarded so far on each stream
985 number of samples forwarded so far on each stream
987 current timestamp of each stream
990 The default value is @code{t1-t2}, which means to always forward the stream
991 that has a smaller timestamp.
996 Stress-test @code{amerge} by randomly sending buffers on the wrong
997 input, while avoiding too much of a desynchronization:
999 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1000 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1008 The filter accepts exactly one parameter, the audio tempo. If not
1009 specified then the filter will assume nominal 1.0 tempo. Tempo must
1010 be in the [0.5, 2.0] range.
1012 @subsection Examples
1016 Slow down audio to 80% tempo:
1022 To speed up audio to 125% tempo:
1030 Make audio easier to listen to on headphones.
1032 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1033 so that when listened to on headphones the stereo image is moved from
1034 inside your head (standard for headphones) to outside and in front of
1035 the listener (standard for speakers).
1041 Mix channels with specific gain levels. The filter accepts the output
1042 channel layout followed by a set of channels definitions.
1044 This filter is also designed to remap efficiently the channels of an audio
1047 The filter accepts parameters of the form:
1048 "@var{l}:@var{outdef}:@var{outdef}:..."
1052 output channel layout or number of channels
1055 output channel specification, of the form:
1056 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1059 output channel to define, either a channel name (FL, FR, etc.) or a channel
1060 number (c0, c1, etc.)
1063 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1066 input channel to use, see out_name for details; it is not possible to mix
1067 named and numbered input channels
1070 If the `=' in a channel specification is replaced by `<', then the gains for
1071 that specification will be renormalized so that the total is 1, thus
1072 avoiding clipping noise.
1074 @subsection Mixing examples
1076 For example, if you want to down-mix from stereo to mono, but with a bigger
1077 factor for the left channel:
1079 pan=1:c0=0.9*c0+0.1*c1
1082 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1083 7-channels surround:
1085 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1088 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1089 that should be preferred (see "-ac" option) unless you have very specific
1092 @subsection Remapping examples
1094 The channel remapping will be effective if, and only if:
1097 @item gain coefficients are zeroes or ones,
1098 @item only one input per channel output,
1101 If all these conditions are satisfied, the filter will notify the user ("Pure
1102 channel mapping detected"), and use an optimized and lossless method to do the
1105 For example, if you have a 5.1 source and want a stereo audio stream by
1106 dropping the extra channels:
1108 pan="stereo: c0=FL : c1=FR"
1111 Given the same source, you can also switch front left and front right channels
1112 and keep the input channel layout:
1114 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1117 If the input is a stereo audio stream, you can mute the front left channel (and
1118 still keep the stereo channel layout) with:
1123 Still with a stereo audio stream input, you can copy the right channel in both
1124 front left and right:
1126 pan="stereo: c0=FR : c1=FR"
1129 @section silencedetect
1131 Detect silence in an audio stream.
1133 This filter logs a message when it detects that the input audio volume is less
1134 or equal to a noise tolerance value for a duration greater or equal to the
1135 minimum detected noise duration.
1137 The printed times and duration are expressed in seconds.
1139 The filter accepts the following options:
1143 Set silence duration until notification (default is 2 seconds).
1146 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1147 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1150 @subsection Examples
1154 Detect 5 seconds of silence with -50dB noise tolerance:
1156 silencedetect=n=-50dB:d=5
1160 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1161 tolerance in @file{silence.mp3}:
1163 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
1168 Synchronize audio data with timestamps by squeezing/stretching it and/or
1169 dropping samples/adding silence when needed.
1171 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1173 The filter accepts the following named parameters:
1177 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1178 by default. When disabled, time gaps are covered with silence.
1181 Minimum difference between timestamps and audio data (in seconds) to trigger
1182 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1183 this filter, try setting this parameter to 0.
1186 Maximum compensation in samples per second. Relevant only with compensate=1.
1190 Assume the first pts should be this value. The time base is 1 / sample rate.
1191 This allows for padding/trimming at the start of stream. By default, no
1192 assumption is made about the first frame's expected pts, so no padding or
1193 trimming is done. For example, this could be set to 0 to pad the beginning with
1194 silence if an audio stream starts after the video stream or to trim any samples
1195 with a negative pts due to encoder delay.
1199 @section channelsplit
1200 Split each channel in input audio stream into a separate output stream.
1202 This filter accepts the following named parameters:
1204 @item channel_layout
1205 Channel layout of the input stream. Default is "stereo".
1208 For example, assuming a stereo input MP3 file
1210 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1212 will create an output Matroska file with two audio streams, one containing only
1213 the left channel and the other the right channel.
1215 To split a 5.1 WAV file into per-channel files
1217 ffmpeg -i in.wav -filter_complex
1218 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1219 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1220 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1225 Remap input channels to new locations.
1227 This filter accepts the following named parameters:
1229 @item channel_layout
1230 Channel layout of the output stream.
1233 Map channels from input to output. The argument is a '|'-separated list of
1234 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1235 @var{in_channel} form. @var{in_channel} can be either the name of the input
1236 channel (e.g. FL for front left) or its index in the input channel layout.
1237 @var{out_channel} is the name of the output channel or its index in the output
1238 channel layout. If @var{out_channel} is not given then it is implicitly an
1239 index, starting with zero and increasing by one for each mapping.
1242 If no mapping is present, the filter will implicitly map input channels to
1243 output channels preserving index.
1245 For example, assuming a 5.1+downmix input MOV file
1247 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1249 will create an output WAV file tagged as stereo from the downmix channels of
1252 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1254 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1258 Join multiple input streams into one multi-channel stream.
1260 The filter accepts the following named parameters:
1264 Number of input streams. Defaults to 2.
1266 @item channel_layout
1267 Desired output channel layout. Defaults to stereo.
1270 Map channels from inputs to output. The argument is a '|'-separated list of
1271 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1272 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1273 can be either the name of the input channel (e.g. FL for front left) or its
1274 index in the specified input stream. @var{out_channel} is the name of the output
1278 The filter will attempt to guess the mappings when those are not specified
1279 explicitly. It does so by first trying to find an unused matching input channel
1280 and if that fails it picks the first unused input channel.
1282 E.g. to join 3 inputs (with properly set channel layouts)
1284 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1287 To build a 5.1 output from 6 single-channel streams:
1289 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1290 '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'
1295 Convert the audio sample format, sample rate and channel layout. This filter is
1296 not meant to be used directly.
1300 Adjust the input audio volume.
1302 The filter accepts the following options:
1307 Expresses how the audio volume will be increased or decreased.
1309 Output values are clipped to the maximum value.
1311 The output audio volume is given by the relation:
1313 @var{output_volume} = @var{volume} * @var{input_volume}
1316 Default value for @var{volume} is 1.0.
1319 Set the mathematical precision.
1321 This determines which input sample formats will be allowed, which affects the
1322 precision of the volume scaling.
1326 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1328 32-bit floating-point; limits input sample format to FLT. (default)
1330 64-bit floating-point; limits input sample format to DBL.
1334 @subsection Examples
1338 Halve the input audio volume:
1342 volume=volume=-6.0206dB
1345 In all the above example the named key for @option{volume} can be
1346 omitted, for example like in:
1352 Increase input audio power by 6 decibels using fixed-point precision:
1354 volume=volume=6dB:precision=fixed
1358 @section volumedetect
1360 Detect the volume of the input video.
1362 The filter has no parameters. The input is not modified. Statistics about
1363 the volume will be printed in the log when the input stream end is reached.
1365 In particular it will show the mean volume (root mean square), maximum
1366 volume (on a per-sample basis), and the beginning of an histogram of the
1367 registered volume values (from the maximum value to a cumulated 1/1000 of
1370 All volumes are in decibels relative to the maximum PCM value.
1372 @subsection Examples
1374 Here is an excerpt of the output:
1376 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1377 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1378 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1379 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1380 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1381 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1382 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1383 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1384 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1390 The mean square energy is approximately -27 dB, or 10^-2.7.
1392 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1394 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1397 In other words, raising the volume by +4 dB does not cause any clipping,
1398 raising it by +5 dB causes clipping for 6 samples, etc.
1400 @c man end AUDIO FILTERS
1402 @chapter Audio Sources
1403 @c man begin AUDIO SOURCES
1405 Below is a description of the currently available audio sources.
1409 Buffer audio frames, and make them available to the filter chain.
1411 This source is mainly intended for a programmatic use, in particular
1412 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1414 It accepts the following named parameters:
1419 Timebase which will be used for timestamps of submitted frames. It must be
1420 either a floating-point number or in @var{numerator}/@var{denominator} form.
1423 The sample rate of the incoming audio buffers.
1426 The sample format of the incoming audio buffers.
1427 Either a sample format name or its corresponging integer representation from
1428 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1430 @item channel_layout
1431 The channel layout of the incoming audio buffers.
1432 Either a channel layout name from channel_layout_map in
1433 @file{libavutil/channel_layout.c} or its corresponding integer representation
1434 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1437 The number of channels of the incoming audio buffers.
1438 If both @var{channels} and @var{channel_layout} are specified, then they
1443 @subsection Examples
1446 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1449 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1450 Since the sample format with name "s16p" corresponds to the number
1451 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1454 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1459 Generate an audio signal specified by an expression.
1461 This source accepts in input one or more expressions (one for each
1462 channel), which are evaluated and used to generate a corresponding
1465 This source accepts the following options:
1469 Set the '|'-separated expressions list for each separate channel. In case the
1470 @option{channel_layout} option is not specified, the selected channel layout
1471 depends on the number of provided expressions.
1473 @item channel_layout, c
1474 Set the channel layout. The number of channels in the specified layout
1475 must be equal to the number of specified expressions.
1478 Set the minimum duration of the sourced audio. See the function
1479 @code{av_parse_time()} for the accepted format.
1480 Note that the resulting duration may be greater than the specified
1481 duration, as the generated audio is always cut at the end of a
1484 If not specified, or the expressed duration is negative, the audio is
1485 supposed to be generated forever.
1488 Set the number of samples per channel per each output frame,
1491 @item sample_rate, s
1492 Specify the sample rate, default to 44100.
1495 Each expression in @var{exprs} can contain the following constants:
1499 number of the evaluated sample, starting from 0
1502 time of the evaluated sample expressed in seconds, starting from 0
1509 @subsection Examples
1519 Generate a sin signal with frequency of 440 Hz, set sample rate to
1522 aevalsrc="sin(440*2*PI*t):s=8000"
1526 Generate a two channels signal, specify the channel layout (Front
1527 Center + Back Center) explicitly:
1529 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
1533 Generate white noise:
1535 aevalsrc="-2+random(0)"
1539 Generate an amplitude modulated signal:
1541 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1545 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1547 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
1554 Null audio source, return unprocessed audio frames. It is mainly useful
1555 as a template and to be employed in analysis / debugging tools, or as
1556 the source for filters which ignore the input data (for example the sox
1559 This source accepts the following options:
1563 @item channel_layout, cl
1565 Specify the channel layout, and can be either an integer or a string
1566 representing a channel layout. The default value of @var{channel_layout}
1569 Check the channel_layout_map definition in
1570 @file{libavutil/channel_layout.c} for the mapping between strings and
1571 channel layout values.
1573 @item sample_rate, r
1574 Specify the sample rate, and defaults to 44100.
1577 Set the number of samples per requested frames.
1581 @subsection Examples
1585 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1587 anullsrc=r=48000:cl=4
1591 Do the same operation with a more obvious syntax:
1593 anullsrc=r=48000:cl=mono
1598 Buffer audio frames, and make them available to the filter chain.
1600 This source is not intended to be part of user-supplied graph descriptions but
1601 for insertion by calling programs through the interface defined in
1602 @file{libavfilter/buffersrc.h}.
1604 It accepts the following named parameters:
1608 Timebase which will be used for timestamps of submitted frames. It must be
1609 either a floating-point number or in @var{numerator}/@var{denominator} form.
1615 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1617 @item channel_layout
1618 Channel layout of the audio data, in the form that can be accepted by
1619 @code{av_get_channel_layout()}.
1622 All the parameters need to be explicitly defined.
1626 Synthesize a voice utterance using the libflite library.
1628 To enable compilation of this filter you need to configure FFmpeg with
1629 @code{--enable-libflite}.
1631 Note that the flite library is not thread-safe.
1633 The filter accepts the following options:
1638 If set to 1, list the names of the available voices and exit
1639 immediately. Default value is 0.
1642 Set the maximum number of samples per frame. Default value is 512.
1645 Set the filename containing the text to speak.
1648 Set the text to speak.
1651 Set the voice to use for the speech synthesis. Default value is
1652 @code{kal}. See also the @var{list_voices} option.
1655 @subsection Examples
1659 Read from file @file{speech.txt}, and synthetize the text using the
1660 standard flite voice:
1662 flite=textfile=speech.txt
1666 Read the specified text selecting the @code{slt} voice:
1668 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1672 Input text to ffmpeg:
1674 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1678 Make @file{ffplay} speak the specified text, using @code{flite} and
1679 the @code{lavfi} device:
1681 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1685 For more information about libflite, check:
1686 @url{http://www.speech.cs.cmu.edu/flite/}
1690 Generate an audio signal made of a sine wave with amplitude 1/8.
1692 The audio signal is bit-exact.
1694 The filter accepts the following options:
1699 Set the carrier frequency. Default is 440 Hz.
1701 @item beep_factor, b
1702 Enable a periodic beep every second with frequency @var{beep_factor} times
1703 the carrier frequency. Default is 0, meaning the beep is disabled.
1705 @item sample_rate, s
1706 Specify the sample rate, default is 44100.
1709 Specify the duration of the generated audio stream.
1711 @item samples_per_frame
1712 Set the number of samples per output frame, default is 1024.
1715 @subsection Examples
1720 Generate a simple 440 Hz sine wave:
1726 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1730 sine=frequency=220:beep_factor=4:duration=5
1735 @c man end AUDIO SOURCES
1737 @chapter Audio Sinks
1738 @c man begin AUDIO SINKS
1740 Below is a description of the currently available audio sinks.
1742 @section abuffersink
1744 Buffer audio frames, and make them available to the end of filter chain.
1746 This sink is mainly intended for programmatic use, in particular
1747 through the interface defined in @file{libavfilter/buffersink.h}
1748 or the options system.
1750 It accepts a pointer to an AVABufferSinkContext structure, which
1751 defines the incoming buffers' formats, to be passed as the opaque
1752 parameter to @code{avfilter_init_filter} for initialization.
1756 Null audio sink, do absolutely nothing with the input audio. It is
1757 mainly useful as a template and to be employed in analysis / debugging
1760 @c man end AUDIO SINKS
1762 @chapter Video Filters
1763 @c man begin VIDEO FILTERS
1765 When you configure your FFmpeg build, you can disable any of the
1766 existing filters using @code{--disable-filters}.
1767 The configure output will show the video filters included in your
1770 Below is a description of the currently available video filters.
1772 @section alphaextract
1774 Extract the alpha component from the input as a grayscale video. This
1775 is especially useful with the @var{alphamerge} filter.
1779 Add or replace the alpha component of the primary input with the
1780 grayscale value of a second input. This is intended for use with
1781 @var{alphaextract} to allow the transmission or storage of frame
1782 sequences that have alpha in a format that doesn't support an alpha
1785 For example, to reconstruct full frames from a normal YUV-encoded video
1786 and a separate video created with @var{alphaextract}, you might use:
1788 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1791 Since this filter is designed for reconstruction, it operates on frame
1792 sequences without considering timestamps, and terminates when either
1793 input reaches end of stream. This will cause problems if your encoding
1794 pipeline drops frames. If you're trying to apply an image as an
1795 overlay to a video stream, consider the @var{overlay} filter instead.
1799 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1800 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1801 Substation Alpha) subtitles files.
1805 Compute the bounding box for the non-black pixels in the input frame
1808 This filter computes the bounding box containing all the pixels with a
1809 luminance value greater than the minimum allowed value.
1810 The parameters describing the bounding box are printed on the filter
1813 @section blackdetect
1815 Detect video intervals that are (almost) completely black. Can be
1816 useful to detect chapter transitions, commercials, or invalid
1817 recordings. Output lines contains the time for the start, end and
1818 duration of the detected black interval expressed in seconds.
1820 In order to display the output lines, you need to set the loglevel at
1821 least to the AV_LOG_INFO value.
1823 The filter accepts the following options:
1826 @item black_min_duration, d
1827 Set the minimum detected black duration expressed in seconds. It must
1828 be a non-negative floating point number.
1830 Default value is 2.0.
1832 @item picture_black_ratio_th, pic_th
1833 Set the threshold for considering a picture "black".
1834 Express the minimum value for the ratio:
1836 @var{nb_black_pixels} / @var{nb_pixels}
1839 for which a picture is considered black.
1840 Default value is 0.98.
1842 @item pixel_black_th, pix_th
1843 Set the threshold for considering a pixel "black".
1845 The threshold expresses the maximum pixel luminance value for which a
1846 pixel is considered "black". The provided value is scaled according to
1847 the following equation:
1849 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1852 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1853 the input video format, the range is [0-255] for YUV full-range
1854 formats and [16-235] for YUV non full-range formats.
1856 Default value is 0.10.
1859 The following example sets the maximum pixel threshold to the minimum
1860 value, and detects only black intervals of 2 or more seconds:
1862 blackdetect=d=2:pix_th=0.00
1867 Detect frames that are (almost) completely black. Can be useful to
1868 detect chapter transitions or commercials. Output lines consist of
1869 the frame number of the detected frame, the percentage of blackness,
1870 the position in the file if known or -1 and the timestamp in seconds.
1872 In order to display the output lines, you need to set the loglevel at
1873 least to the AV_LOG_INFO value.
1875 The filter accepts the following options:
1880 Set the percentage of the pixels that have to be below the threshold, defaults
1883 @item threshold, thresh
1884 Set the threshold below which a pixel value is considered black, defaults to
1891 Blend two video frames into each other.
1893 It takes two input streams and outputs one stream, the first input is the
1894 "top" layer and second input is "bottom" layer.
1895 Output terminates when shortest input terminates.
1897 A description of the accepted options follows.
1905 Set blend mode for specific pixel component or all pixel components in case
1906 of @var{all_mode}. Default value is @code{normal}.
1908 Available values for component modes are:
1941 Set blend opacity for specific pixel component or all pixel components in case
1942 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1949 Set blend expression for specific pixel component or all pixel components in case
1950 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1952 The expressions can use the following variables:
1956 The sequential number of the filtered frame, starting from @code{0}.
1960 the coordinates of the current sample
1964 the width and height of currently filtered plane
1968 Width and height scale depending on the currently filtered plane. It is the
1969 ratio between the corresponding luma plane number of pixels and the current
1970 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1971 @code{0.5,0.5} for chroma planes.
1974 Time of the current frame, expressed in seconds.
1977 Value of pixel component at current location for first video frame (top layer).
1980 Value of pixel component at current location for second video frame (bottom layer).
1984 @subsection Examples
1988 Apply transition from bottom layer to top layer in first 10 seconds:
1990 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
1994 Apply 1x1 checkerboard effect:
1996 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2002 Apply boxblur algorithm to the input video.
2004 The filter accepts the following options:
2008 @item luma_radius, lr
2009 @item luma_power, lp
2010 @item chroma_radius, cr
2011 @item chroma_power, cp
2012 @item alpha_radius, ar
2013 @item alpha_power, ap
2017 A description of the accepted options follows.
2020 @item luma_radius, lr
2021 @item chroma_radius, cr
2022 @item alpha_radius, ar
2023 Set an expression for the box radius in pixels used for blurring the
2024 corresponding input plane.
2026 The radius value must be a non-negative number, and must not be
2027 greater than the value of the expression @code{min(w,h)/2} for the
2028 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2031 Default value for @option{luma_radius} is "2". If not specified,
2032 @option{chroma_radius} and @option{alpha_radius} default to the
2033 corresponding value set for @option{luma_radius}.
2035 The expressions can contain the following constants:
2038 the input width and height in pixels
2041 the input chroma image width and height in pixels
2044 horizontal and vertical chroma subsample values. For example for the
2045 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2048 @item luma_power, lp
2049 @item chroma_power, cp
2050 @item alpha_power, ap
2051 Specify how many times the boxblur filter is applied to the
2052 corresponding plane.
2054 Default value for @option{luma_power} is 2. If not specified,
2055 @option{chroma_power} and @option{alpha_power} default to the
2056 corresponding value set for @option{luma_power}.
2058 A value of 0 will disable the effect.
2061 @subsection Examples
2065 Apply a boxblur filter with luma, chroma, and alpha radius
2068 boxblur=luma_radius=2:luma_power=1
2073 Set luma radius to 2, alpha and chroma radius to 0:
2075 boxblur=2:1:cr=0:ar=0
2079 Set luma and chroma radius to a fraction of the video dimension:
2081 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2085 @section colormatrix
2087 Convert color matrix.
2089 The filter accepts the following options:
2094 Specify the source and destination color matrix. Both values must be
2097 The accepted values are:
2113 For example to convert from BT.601 to SMPTE-240M, use the command:
2115 colormatrix=bt601:smpte240m
2120 Copy the input source unchanged to the output. Mainly useful for
2125 Crop the input video to given dimensions.
2127 The filter accepts the following options:
2131 Width of the output video. It defaults to @code{iw}.
2132 This expression is evaluated only once during the filter
2136 Height of the output video. It defaults to @code{ih}.
2137 This expression is evaluated only once during the filter
2141 Horizontal position, in the input video, of the left edge of the output video.
2142 It defaults to @code{(in_w-out_w)/2}.
2143 This expression is evaluated per-frame.
2146 Vertical position, in the input video, of the top edge of the output video.
2147 It defaults to @code{(in_h-out_h)/2}.
2148 This expression is evaluated per-frame.
2151 If set to 1 will force the output display aspect ratio
2152 to be the same of the input, by changing the output sample aspect
2153 ratio. It defaults to 0.
2156 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2157 expressions containing the following constants:
2161 the computed values for @var{x} and @var{y}. They are evaluated for
2165 the input width and height
2168 same as @var{in_w} and @var{in_h}
2171 the output (cropped) width and height
2174 same as @var{out_w} and @var{out_h}
2177 same as @var{iw} / @var{ih}
2180 input sample aspect ratio
2183 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2186 horizontal and vertical chroma subsample values. For example for the
2187 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2190 the number of input frame, starting from 0
2193 the position in the file of the input frame, NAN if unknown
2196 timestamp expressed in seconds, NAN if the input timestamp is unknown
2200 The expression for @var{out_w} may depend on the value of @var{out_h},
2201 and the expression for @var{out_h} may depend on @var{out_w}, but they
2202 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2203 evaluated after @var{out_w} and @var{out_h}.
2205 The @var{x} and @var{y} parameters specify the expressions for the
2206 position of the top-left corner of the output (non-cropped) area. They
2207 are evaluated for each frame. If the evaluated value is not valid, it
2208 is approximated to the nearest valid value.
2210 The expression for @var{x} may depend on @var{y}, and the expression
2211 for @var{y} may depend on @var{x}.
2213 @subsection Examples
2217 Crop area with size 100x100 at position (12,34).
2222 Using named options, the example above becomes:
2224 crop=w=100:h=100:x=12:y=34
2228 Crop the central input area with size 100x100:
2234 Crop the central input area with size 2/3 of the input video:
2236 crop=2/3*in_w:2/3*in_h
2240 Crop the input video central square:
2247 Delimit the rectangle with the top-left corner placed at position
2248 100:100 and the right-bottom corner corresponding to the right-bottom
2249 corner of the input image:
2251 crop=in_w-100:in_h-100:100:100
2255 Crop 10 pixels from the left and right borders, and 20 pixels from
2256 the top and bottom borders
2258 crop=in_w-2*10:in_h-2*20
2262 Keep only the bottom right quarter of the input image:
2264 crop=in_w/2:in_h/2:in_w/2:in_h/2
2268 Crop height for getting Greek harmony:
2270 crop=in_w:1/PHI*in_w
2274 Appply trembling effect:
2276 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)
2280 Apply erratic camera effect depending on timestamp:
2282 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)"
2286 Set x depending on the value of y:
2288 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2294 Auto-detect crop size.
2296 Calculate necessary cropping parameters and prints the recommended
2297 parameters through the logging system. The detected dimensions
2298 correspond to the non-black area of the input video.
2300 The filter accepts the following options:
2305 Set higher black value threshold, which can be optionally specified
2306 from nothing (0) to everything (255). An intensity value greater
2307 to the set value is considered non-black. Default value is 24.
2310 Set the value for which the width/height should be divisible by. The
2311 offset is automatically adjusted to center the video. Use 2 to get
2312 only even dimensions (needed for 4:2:2 video). 16 is best when
2313 encoding to most video codecs. Default value is 16.
2315 @item reset_count, reset
2316 Set the counter that determines after how many frames cropdetect will
2317 reset the previously detected largest video area and start over to
2318 detect the current optimal crop area. Default value is 0.
2320 This can be useful when channel logos distort the video area. 0
2321 indicates never reset and return the largest area encountered during
2327 Apply color adjustments using curves.
2329 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2330 component (red, green and blue) has its values defined by @var{N} key points
2331 tied from each other using a smooth curve. The x-axis represents the pixel
2332 values from the input frame, and the y-axis the new pixel values to be set for
2335 By default, a component curve is defined by the two points @var{(0;0)} and
2336 @var{(1;1)}. This creates a straight line where each original pixel value is
2337 "adjusted" to its own value, which means no change to the image.
2339 The filter allows you to redefine these two points and add some more. A new
2340 curve (using a natural cubic spline interpolation) will be define to pass
2341 smoothly through all these new coordinates. The new defined points needs to be
2342 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2343 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2344 the vector spaces, the values will be clipped accordingly.
2346 If there is no key point defined in @code{x=0}, the filter will automatically
2347 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2348 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2350 The filter accepts the following options:
2354 Select one of the available color presets. This option can be used in addition
2355 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2356 options takes priority on the preset values.
2357 Available presets are:
2360 @item color_negative
2363 @item increase_contrast
2365 @item linear_contrast
2366 @item medium_contrast
2368 @item strong_contrast
2371 Default is @code{none}.
2373 Set the key points for the red component.
2375 Set the key points for the green component.
2377 Set the key points for the blue component.
2379 Set the key points for all components.
2380 Can be used in addition to the other key points component
2381 options. In this case, the unset component(s) will fallback on this
2382 @option{all} setting.
2385 To avoid some filtergraph syntax conflicts, each key points list need to be
2386 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2388 @subsection Examples
2392 Increase slightly the middle level of blue:
2394 curves=blue='0.5/0.58'
2400 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2402 Here we obtain the following coordinates for each components:
2405 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2407 @code{(0;0) (0.50;0.48) (1;1)}
2409 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2413 The previous example can also be achieved with the associated built-in preset:
2415 curves=preset=vintage
2427 Drop frames that do not differ greatly from the previous frame in
2428 order to reduce frame rate.
2430 The main use of this filter is for very-low-bitrate encoding
2431 (e.g. streaming over dialup modem), but it could in theory be used for
2432 fixing movies that were inverse-telecined incorrectly.
2434 A description of the accepted options follows.
2438 Set the maximum number of consecutive frames which can be dropped (if
2439 positive), or the minimum interval between dropped frames (if
2440 negative). If the value is 0, the frame is dropped unregarding the
2441 number of previous sequentially dropped frames.
2448 Set the dropping threshold values.
2450 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2451 represent actual pixel value differences, so a threshold of 64
2452 corresponds to 1 unit of difference for each pixel, or the same spread
2453 out differently over the block.
2455 A frame is a candidate for dropping if no 8x8 blocks differ by more
2456 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2457 meaning the whole image) differ by more than a threshold of @option{lo}.
2459 Default value for @option{hi} is 64*12, default value for @option{lo} is
2460 64*5, and default value for @option{frac} is 0.33.
2465 Suppress a TV station logo by a simple interpolation of the surrounding
2466 pixels. Just set a rectangle covering the logo and watch it disappear
2467 (and sometimes something even uglier appear - your mileage may vary).
2469 This filter accepts the following options:
2473 Specify the top left corner coordinates of the logo. They must be
2477 Specify the width and height of the logo to clear. They must be
2481 Specify the thickness of the fuzzy edge of the rectangle (added to
2482 @var{w} and @var{h}). The default value is 4.
2485 When set to 1, a green rectangle is drawn on the screen to simplify
2486 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2487 @var{band} is set to 4. The default value is 0.
2491 @subsection Examples
2495 Set a rectangle covering the area with top left corner coordinates 0,0
2496 and size 100x77, setting a band of size 10:
2498 delogo=x=0:y=0:w=100:h=77:band=10
2505 Attempt to fix small changes in horizontal and/or vertical shift. This
2506 filter helps remove camera shake from hand-holding a camera, bumping a
2507 tripod, moving on a vehicle, etc.
2509 The filter accepts the following options:
2517 Specify a rectangular area where to limit the search for motion
2519 If desired the search for motion vectors can be limited to a
2520 rectangular area of the frame defined by its top left corner, width
2521 and height. These parameters have the same meaning as the drawbox
2522 filter which can be used to visualise the position of the bounding
2525 This is useful when simultaneous movement of subjects within the frame
2526 might be confused for camera motion by the motion vector search.
2528 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2529 then the full frame is used. This allows later options to be set
2530 without specifying the bounding box for the motion vector search.
2532 Default - search the whole frame.
2536 Specify the maximum extent of movement in x and y directions in the
2537 range 0-64 pixels. Default 16.
2540 Specify how to generate pixels to fill blanks at the edge of the
2541 frame. Available values are:
2544 Fill zeroes at blank locations
2546 Original image at blank locations
2548 Extruded edge value at blank locations
2550 Mirrored edge at blank locations
2552 Default value is @samp{mirror}.
2555 Specify the blocksize to use for motion search. Range 4-128 pixels,
2559 Specify the contrast threshold for blocks. Only blocks with more than
2560 the specified contrast (difference between darkest and lightest
2561 pixels) will be considered. Range 1-255, default 125.
2564 Specify the search strategy. Available values are:
2567 Set exhaustive search
2569 Set less exhaustive search.
2571 Default value is @samp{exhaustive}.
2574 If set then a detailed log of the motion search is written to the
2578 If set to 1, specify using OpenCL capabilities, only available if
2579 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2585 Draw a colored box on the input image.
2587 This filter accepts the following options:
2591 Specify the top left corner coordinates of the box. Default to 0.
2595 Specify the width and height of the box, if 0 they are interpreted as
2596 the input width and height. Default to 0.
2599 Specify the color of the box to write, it can be the name of a color
2600 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2601 value @code{invert} is used, the box edge color is the same as the
2602 video with inverted luma.
2605 Set the thickness of the box edge. Default value is @code{4}.
2608 @subsection Examples
2612 Draw a black box around the edge of the input image:
2618 Draw a box with color red and an opacity of 50%:
2620 drawbox=10:20:200:60:red@@0.5
2623 The previous example can be specified as:
2625 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2629 Fill the box with pink color:
2631 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2638 Draw text string or text from specified file on top of video using the
2639 libfreetype library.
2641 To enable compilation of this filter you need to configure FFmpeg with
2642 @code{--enable-libfreetype}.
2646 The description of the accepted parameters follows.
2651 Used to draw a box around text using background color.
2652 Value should be either 1 (enable) or 0 (disable).
2653 The default value of @var{box} is 0.
2656 The color to be used for drawing box around text.
2657 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2658 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2659 The default value of @var{boxcolor} is "white".
2662 Set an expression which specifies if the text should be drawn. If the
2663 expression evaluates to 0, the text is not drawn. This is useful for
2664 specifying that the text should be drawn only when specific conditions
2667 Default value is "1".
2669 See below for the list of accepted constants and functions.
2672 Select how the @var{text} is expanded. Can be either @code{none},
2673 @code{strftime} (deprecated) or
2674 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2678 If true, check and fix text coords to avoid clipping.
2681 The color to be used for drawing fonts.
2682 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2683 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2684 The default value of @var{fontcolor} is "black".
2687 The font file to be used for drawing text. Path must be included.
2688 This parameter is mandatory.
2691 The font size to be used for drawing text.
2692 The default value of @var{fontsize} is 16.
2695 Flags to be used for loading the fonts.
2697 The flags map the corresponding flags supported by libfreetype, and are
2698 a combination of the following values:
2705 @item vertical_layout
2706 @item force_autohint
2709 @item ignore_global_advance_width
2711 @item ignore_transform
2718 Default value is "render".
2720 For more information consult the documentation for the FT_LOAD_*
2724 The color to be used for drawing a shadow behind the drawn text. It
2725 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2726 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2727 The default value of @var{shadowcolor} is "black".
2729 @item shadowx, shadowy
2730 The x and y offsets for the text shadow position with respect to the
2731 position of the text. They can be either positive or negative
2732 values. Default value for both is "0".
2735 The size in number of spaces to use for rendering the tab.
2739 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2740 format. It can be used with or without text parameter. @var{timecode_rate}
2741 option must be specified.
2743 @item timecode_rate, rate, r
2744 Set the timecode frame rate (timecode only).
2747 The text string to be drawn. The text must be a sequence of UTF-8
2749 This parameter is mandatory if no file is specified with the parameter
2753 A text file containing text to be drawn. The text must be a sequence
2754 of UTF-8 encoded characters.
2756 This parameter is mandatory if no text string is specified with the
2757 parameter @var{text}.
2759 If both @var{text} and @var{textfile} are specified, an error is thrown.
2762 If set to 1, the @var{textfile} will be reloaded before each frame.
2763 Be sure to update it atomically, or it may be read partially, or even fail.
2766 The expressions which specify the offsets where text will be drawn
2767 within the video frame. They are relative to the top/left border of the
2770 The default value of @var{x} and @var{y} is "0".
2772 See below for the list of accepted constants and functions.
2775 The parameters for @var{x} and @var{y} are expressions containing the
2776 following constants and functions:
2780 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2783 horizontal and vertical chroma subsample values. For example for the
2784 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2787 the height of each text line
2795 @item max_glyph_a, ascent
2796 the maximum distance from the baseline to the highest/upper grid
2797 coordinate used to place a glyph outline point, for all the rendered
2799 It is a positive value, due to the grid's orientation with the Y axis
2802 @item max_glyph_d, descent
2803 the maximum distance from the baseline to the lowest grid coordinate
2804 used to place a glyph outline point, for all the rendered glyphs.
2805 This is a negative value, due to the grid's orientation, with the Y axis
2809 maximum glyph height, that is the maximum height for all the glyphs
2810 contained in the rendered text, it is equivalent to @var{ascent} -
2814 maximum glyph width, that is the maximum width for all the glyphs
2815 contained in the rendered text
2818 the number of input frame, starting from 0
2820 @item rand(min, max)
2821 return a random number included between @var{min} and @var{max}
2824 input sample aspect ratio
2827 timestamp expressed in seconds, NAN if the input timestamp is unknown
2830 the height of the rendered text
2833 the width of the rendered text
2836 the x and y offset coordinates where the text is drawn.
2838 These parameters allow the @var{x} and @var{y} expressions to refer
2839 each other, so you can for example specify @code{y=x/dar}.
2842 If libavfilter was built with @code{--enable-fontconfig}, then
2843 @option{fontfile} can be a fontconfig pattern or omitted.
2845 @anchor{drawtext_expansion}
2846 @subsection Text expansion
2848 If @option{expansion} is set to @code{strftime},
2849 the filter recognizes strftime() sequences in the provided text and
2850 expands them accordingly. Check the documentation of strftime(). This
2851 feature is deprecated.
2853 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2855 If @option{expansion} is set to @code{normal} (which is the default),
2856 the following expansion mechanism is used.
2858 The backslash character '\', followed by any character, always expands to
2859 the second character.
2861 Sequence of the form @code{%@{...@}} are expanded. The text between the
2862 braces is a function name, possibly followed by arguments separated by ':'.
2863 If the arguments contain special characters or delimiters (':' or '@}'),
2864 they should be escaped.
2866 Note that they probably must also be escaped as the value for the
2867 @option{text} option in the filter argument string and as the filter
2868 argument in the filtergraph description, and possibly also for the shell,
2869 that makes up to four levels of escaping; using a text file avoids these
2872 The following functions are available:
2877 The expression evaluation result.
2879 It must take one argument specifying the expression to be evaluated,
2880 which accepts the same constants and functions as the @var{x} and
2881 @var{y} values. Note that not all constants should be used, for
2882 example the text size is not known when evaluating the expression, so
2883 the constants @var{text_w} and @var{text_h} will have an undefined
2887 The time at which the filter is running, expressed in UTC.
2888 It can accept an argument: a strftime() format string.
2891 The time at which the filter is running, expressed in the local time zone.
2892 It can accept an argument: a strftime() format string.
2895 The frame number, starting from 0.
2898 The timestamp of the current frame, in seconds, with microsecond accuracy.
2902 @subsection Examples
2906 Draw "Test Text" with font FreeSerif, using the default values for the
2907 optional parameters.
2910 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2914 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2915 and y=50 (counting from the top-left corner of the screen), text is
2916 yellow with a red box around it. Both the text and the box have an
2920 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2921 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2924 Note that the double quotes are not necessary if spaces are not used
2925 within the parameter list.
2928 Show the text at the center of the video frame:
2930 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2934 Show a text line sliding from right to left in the last row of the video
2935 frame. The file @file{LONG_LINE} is assumed to contain a single line
2938 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2942 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2944 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2948 Draw a single green letter "g", at the center of the input video.
2949 The glyph baseline is placed at half screen height.
2951 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2955 Show text for 1 second every 3 seconds:
2957 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2961 Use fontconfig to set the font. Note that the colons need to be escaped.
2963 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2967 Print the date of a real-time encoding (see strftime(3)):
2969 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2974 For more information about libfreetype, check:
2975 @url{http://www.freetype.org/}.
2977 For more information about fontconfig, check:
2978 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2982 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2984 The filter accepts the following options:
2988 Set low and high threshold values used by the Canny thresholding
2991 The high threshold selects the "strong" edge pixels, which are then
2992 connected through 8-connectivity with the "weak" edge pixels selected
2993 by the low threshold.
2995 @var{low} and @var{high} threshold values must be choosen in the range
2996 [0,1], and @var{low} should be lesser or equal to @var{high}.
2998 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3004 edgedetect=low=0.1:high=0.4
3009 Apply fade-in/out effect to input video.
3011 This filter accepts the following options:
3015 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3017 Default is @code{in}.
3019 @item start_frame, s
3020 Specify the number of the start frame for starting to apply the fade
3021 effect. Default is 0.
3024 The number of frames for which the fade effect has to last. At the end of the
3025 fade-in effect the output video will have the same intensity as the input video,
3026 at the end of the fade-out transition the output video will be completely black.
3030 If set to 1, fade only alpha channel, if one exists on the input.
3034 @subsection Examples
3038 Fade in first 30 frames of video:
3043 The command above is equivalent to:
3049 Fade out last 45 frames of a 200-frame video:
3052 fade=type=out:start_frame=155:nb_frames=45
3056 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3058 fade=in:0:25, fade=out:975:25
3062 Make first 5 frames black, then fade in from frame 5-24:
3068 Fade in alpha over first 25 frames of video:
3070 fade=in:0:25:alpha=1
3076 Extract a single field from an interlaced image using stride
3077 arithmetic to avoid wasting CPU time. The output frames are marked as
3080 The filter accepts the following options:
3084 Specify whether to extract the top (if the value is @code{0} or
3085 @code{top}) or the bottom field (if the value is @code{1} or
3091 Transform the field order of the input video.
3093 This filter accepts the following options:
3098 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3099 for bottom field first.
3102 Default value is @samp{tff}.
3104 Transformation is achieved by shifting the picture content up or down
3105 by one line, and filling the remaining line with appropriate picture content.
3106 This method is consistent with most broadcast field order converters.
3108 If the input video is not flagged as being interlaced, or it is already
3109 flagged as being of the required output field order then this filter does
3110 not alter the incoming video.
3112 This filter is very useful when converting to or from PAL DV material,
3113 which is bottom field first.
3117 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3122 Buffer input images and send them when they are requested.
3124 This filter is mainly useful when auto-inserted by the libavfilter
3127 The filter does not take parameters.
3132 Convert the input video to one of the specified pixel formats.
3133 Libavfilter will try to pick one that is supported for the input to
3136 This filter accepts the following parameters:
3140 A '|'-separated list of pixel format names, for example
3141 "pix_fmts=yuv420p|monow|rgb24".
3145 @subsection Examples
3149 Convert the input video to the format @var{yuv420p}
3151 format=pix_fmts=yuv420p
3154 Convert the input video to any of the formats in the list
3156 format=pix_fmts=yuv420p|yuv444p|yuv410p
3162 Convert the video to specified constant frame rate by duplicating or dropping
3163 frames as necessary.
3165 This filter accepts the following named parameters:
3169 Desired output frame rate. The default is @code{25}.
3174 Possible values are:
3177 zero round towards 0
3181 round towards -infinity
3183 round towards +infinity
3187 The default is @code{near}.
3191 Alternatively, the options can be specified as a flat string:
3192 @var{fps}[:@var{round}].
3194 See also the @ref{setpts} filter.
3198 Select one frame every N-th frame.
3200 This filter accepts the following option:
3203 Select frame after every @code{step} frames.
3204 Allowed values are positive integers higher than 0. Default value is @code{1}.
3210 Apply a frei0r effect to the input video.
3212 To enable compilation of this filter you need to install the frei0r
3213 header and configure FFmpeg with @code{--enable-frei0r}.
3215 This filter accepts the following options:
3220 The name to the frei0r effect to load. If the environment variable
3221 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3222 directories specified by the colon separated list in @env{FREIOR_PATH},
3223 otherwise in the standard frei0r paths, which are in this order:
3224 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3225 @file{/usr/lib/frei0r-1/}.
3228 A '|'-separated list of parameters to pass to the frei0r effect.
3232 A frei0r effect parameter can be a boolean (whose values are specified
3233 with "y" and "n"), a double, a color (specified by the syntax
3234 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3235 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3236 description), a position (specified by the syntax @var{X}/@var{Y},
3237 @var{X} and @var{Y} being float numbers) and a string.
3239 The number and kind of parameters depend on the loaded effect. If an
3240 effect parameter is not specified the default value is set.
3242 @subsection Examples
3246 Apply the distort0r effect, set the first two double parameters:
3248 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3252 Apply the colordistance effect, take a color as first parameter:
3254 frei0r=colordistance:0.2/0.3/0.4
3255 frei0r=colordistance:violet
3256 frei0r=colordistance:0x112233
3260 Apply the perspective effect, specify the top left and top right image
3263 frei0r=perspective:0.2/0.2|0.8/0.2
3267 For more information see:
3268 @url{http://frei0r.dyne.org}
3272 The filter accepts the following options:
3276 the luminance expression
3278 the chrominance blue expression
3280 the chrominance red expression
3282 the alpha expression
3285 If one of the chrominance expression is not defined, it falls back on the other
3286 one. If no alpha expression is specified it will evaluate to opaque value.
3287 If none of chrominance expressions are
3288 specified, they will evaluate the luminance expression.
3290 The expressions can use the following variables and functions:
3294 The sequential number of the filtered frame, starting from @code{0}.
3298 The coordinates of the current sample.
3302 The width and height of the image.
3306 Width and height scale depending on the currently filtered plane. It is the
3307 ratio between the corresponding luma plane number of pixels and the current
3308 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3309 @code{0.5,0.5} for chroma planes.
3312 Time of the current frame, expressed in seconds.
3315 Return the value of the pixel at location (@var{x},@var{y}) of the current
3319 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3323 Return the value of the pixel at location (@var{x},@var{y}) of the
3324 blue-difference chroma plane. Returns 0 if there is no such plane.
3327 Return the value of the pixel at location (@var{x},@var{y}) of the
3328 red-difference chroma plane. Returns 0 if there is no such plane.
3331 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3332 plane. Returns 0 if there is no such plane.
3335 For functions, if @var{x} and @var{y} are outside the area, the value will be
3336 automatically clipped to the closer edge.
3338 @subsection Examples
3342 Flip the image horizontally:
3348 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3349 wavelength of 100 pixels:
3351 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3355 Generate a fancy enigmatic moving light:
3357 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
3361 Generate a quick emboss effect:
3363 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
3369 Fix the banding artifacts that are sometimes introduced into nearly flat
3370 regions by truncation to 8bit color depth.
3371 Interpolate the gradients that should go where the bands are, and
3374 This filter is designed for playback only. Do not use it prior to
3375 lossy compression, because compression tends to lose the dither and
3376 bring back the bands.
3378 This filter accepts the following options:
3383 The maximum amount by which the filter will change any one pixel. Also the
3384 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3385 64, default value is 1.2, out-of-range values will be clipped to the valid
3389 The neighborhood to fit the gradient to. A larger radius makes for smoother
3390 gradients, but also prevents the filter from modifying the pixels near detailed
3391 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3392 will be clipped to the valid range.
3396 Alternatively, the options can be specified as a flat string:
3397 @var{strength}[:@var{radius}]
3399 @subsection Examples
3403 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3409 Specify radius, omitting the strength (which will fall-back to the default
3419 Flip the input video horizontally.
3421 For example to horizontally flip the input video with @command{ffmpeg}:
3423 ffmpeg -i in.avi -vf "hflip" out.avi
3427 This filter applies a global color histogram equalization on a
3430 It can be used to correct video that has a compressed range of pixel
3431 intensities. The filter redistributes the pixel intensities to
3432 equalize their distribution across the intensity range. It may be
3433 viewed as an "automatically adjusting contrast filter". This filter is
3434 useful only for correcting degraded or poorly captured source
3437 The filter accepts the following options:
3441 Determine the amount of equalization to be applied. As the strength
3442 is reduced, the distribution of pixel intensities more-and-more
3443 approaches that of the input frame. The value must be a float number
3444 in the range [0,1] and defaults to 0.200.
3447 Set the maximum intensity that can generated and scale the output
3448 values appropriately. The strength should be set as desired and then
3449 the intensity can be limited if needed to avoid washing-out. The value
3450 must be a float number in the range [0,1] and defaults to 0.210.
3453 Set the antibanding level. If enabled the filter will randomly vary
3454 the luminance of output pixels by a small amount to avoid banding of
3455 the histogram. Possible values are @code{none}, @code{weak} or
3456 @code{strong}. It defaults to @code{none}.
3461 Compute and draw a color distribution histogram for the input video.
3463 The computed histogram is a representation of distribution of color components
3466 The filter accepts the following options:
3472 It accepts the following values:
3475 standard histogram that display color components distribution in an image.
3476 Displays color graph for each color component. Shows distribution
3477 of the Y, U, V, A or G, B, R components, depending on input format,
3478 in current frame. Bellow each graph is color component scale meter.
3481 chroma values in vectorscope, if brighter more such chroma values are
3482 distributed in an image.
3483 Displays chroma values (U/V color placement) in two dimensional graph
3484 (which is called a vectorscope). It can be used to read of the hue and
3485 saturation of the current frame. At a same time it is a histogram.
3486 The whiter a pixel in the vectorscope, the more pixels of the input frame
3487 correspond to that pixel (that is the more pixels have this chroma value).
3488 The V component is displayed on the horizontal (X) axis, with the leftmost
3489 side being V = 0 and the rightmost side being V = 255.
3490 The U component is displayed on the vertical (Y) axis, with the top
3491 representing U = 0 and the bottom representing U = 255.
3493 The position of a white pixel in the graph corresponds to the chroma value
3494 of a pixel of the input clip. So the graph can be used to read of the
3495 hue (color flavor) and the saturation (the dominance of the hue in the color).
3496 As the hue of a color changes, it moves around the square. At the center of
3497 the square, the saturation is zero, which means that the corresponding pixel
3498 has no color. If you increase the amount of a specific color, while leaving
3499 the other colors unchanged, the saturation increases, and you move towards
3500 the edge of the square.
3503 chroma values in vectorscope, similar as @code{color} but actual chroma values
3507 per row/column color component graph. In row mode graph in the left side represents
3508 color component value 0 and right side represents value = 255. In column mode top
3509 side represents color component value = 0 and bottom side represents value = 255.
3511 Default value is @code{levels}.
3514 Set height of level in @code{levels}. Default value is @code{200}.
3515 Allowed range is [50, 2048].
3518 Set height of color scale in @code{levels}. Default value is @code{12}.
3519 Allowed range is [0, 40].
3522 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3523 of same luminance values across input rows/columns are distributed.
3524 Default value is @code{10}. Allowed range is [1, 255].
3527 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3528 Default is @code{row}.
3531 Set display mode for @code{waveform} and @code{levels}.
3532 It accepts the following values:
3535 Display separate graph for the color components side by side in
3536 @code{row} waveform mode or one below other in @code{column} waveform mode
3537 for @code{waveform} histogram mode. For @code{levels} histogram mode
3538 per color component graphs are placed one bellow other.
3540 This display mode in @code{waveform} histogram mode makes it easy to spot
3541 color casts in the highlights and shadows of an image, by comparing the
3542 contours of the top and the bottom of each waveform.
3543 Since whites, grays, and blacks are characterized by
3544 exactly equal amounts of red, green, and blue, neutral areas of the
3545 picture should display three waveforms of roughly equal width/height.
3546 If not, the correction is easy to make by making adjustments to level the
3550 Presents information that's identical to that in the @code{parade}, except
3551 that the graphs representing color components are superimposed directly
3554 This display mode in @code{waveform} histogram mode can make it easier to spot
3555 the relative differences or similarities in overlapping areas of the color
3556 components that are supposed to be identical, such as neutral whites, grays,
3559 Default is @code{parade}.
3562 @subsection Examples
3567 Calculate and draw histogram:
3569 ffplay -i input -vf histogram
3576 High precision/quality 3d denoise filter. This filter aims to reduce
3577 image noise producing smooth images and making still images really
3578 still. It should enhance compressibility.
3580 It accepts the following optional parameters:
3584 a non-negative float number which specifies spatial luma strength,
3587 @item chroma_spatial
3588 a non-negative float number which specifies spatial chroma strength,
3589 defaults to 3.0*@var{luma_spatial}/4.0
3592 a float number which specifies luma temporal strength, defaults to
3593 6.0*@var{luma_spatial}/4.0
3596 a float number which specifies chroma temporal strength, defaults to
3597 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3602 Modify the hue and/or the saturation of the input.
3604 This filter accepts the following options:
3608 Specify the hue angle as a number of degrees. It accepts an expression,
3609 and defaults to "0".
3612 Specify the saturation in the [-10,10] range. It accepts a float number and
3616 Specify the hue angle as a number of radians. It accepts a float
3617 number or an expression, and defaults to "0".
3620 @option{h} and @option{H} are mutually exclusive, and can't be
3621 specified at the same time.
3623 The @option{h}, @option{H} and @option{s} option values are
3624 expressions containing the following constants:
3628 frame count of the input frame starting from 0
3631 presentation timestamp of the input frame expressed in time base units
3634 frame rate of the input video, NAN if the input frame rate is unknown
3637 timestamp expressed in seconds, NAN if the input timestamp is unknown
3640 time base of the input video
3643 @subsection Examples
3647 Set the hue to 90 degrees and the saturation to 1.0:
3653 Same command but expressing the hue in radians:
3659 Rotate hue and make the saturation swing between 0
3660 and 2 over a period of 1 second:
3662 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3666 Apply a 3 seconds saturation fade-in effect starting at 0:
3671 The general fade-in expression can be written as:
3673 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3677 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3679 hue="s=max(0\, min(1\, (8-t)/3))"
3682 The general fade-out expression can be written as:
3684 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3689 @subsection Commands
3691 This filter supports the following commands:
3696 Modify the hue and/or the saturation of the input video.
3697 The command accepts the same syntax of the corresponding option.
3699 If the specified expression is not valid, it is kept at its current
3705 Detect video interlacing type.
3707 This filter tries to detect if the input is interlaced or progressive,
3708 top or bottom field first.
3710 The filter accepts the following options:
3714 Set interlacing threshold.
3716 Set progressive threshold.
3721 Deinterleave or interleave fields.
3723 This filter allows to process interlaced images fields without
3724 deinterlacing them. Deinterleaving splits the input frame into 2
3725 fields (so called half pictures). Odd lines are moved to the top
3726 half of the output image, even lines to the bottom half.
3727 You can process (filter) them independently and then re-interleave them.
3729 The filter accepts the following options:
3733 @item chroma_mode, s
3735 Available values for @var{luma_mode}, @var{chroma_mode} and
3736 @var{alpha_mode} are:
3742 @item deinterleave, d
3743 Deinterleave fields, placing one above the other.
3746 Interleave fields. Reverse the effect of deinterleaving.
3748 Default value is @code{none}.
3751 @item chroma_swap, cs
3752 @item alpha_swap, as
3753 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3758 Simple interlacing filter from progressive contents. This interleaves upper (or
3759 lower) lines from odd frames with lower (or upper) lines from even frames,
3760 halving the frame rate and preserving image height.
3763 Original Original New Frame
3764 Frame 'j' Frame 'j+1' (tff)
3765 ========== =========== ==================
3766 Line 0 --------------------> Frame 'j' Line 0
3767 Line 1 Line 1 ----> Frame 'j+1' Line 1
3768 Line 2 ---------------------> Frame 'j' Line 2
3769 Line 3 Line 3 ----> Frame 'j+1' Line 3
3771 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
3774 It accepts the following optional parameters:
3778 determines whether the interlaced frame is taken from the even (tff - default)
3779 or odd (bff) lines of the progressive frame.
3782 Enable (default) or disable the vertical lowpass filter to avoid twitter
3783 interlacing and reduce moire patterns.
3788 Deinterlace input video by applying Donald Graft's adaptive kernel
3789 deinterling. Work on interlaced parts of a video to produce
3792 The description of the accepted parameters follows.
3796 Set the threshold which affects the filter's tolerance when
3797 determining if a pixel line must be processed. It must be an integer
3798 in the range [0,255] and defaults to 10. A value of 0 will result in
3799 applying the process on every pixels.
3802 Paint pixels exceeding the threshold value to white if set to 1.
3806 Set the fields order. Swap fields if set to 1, leave fields alone if
3810 Enable additional sharpening if set to 1. Default is 0.
3813 Enable twoway sharpening if set to 1. Default is 0.
3816 @subsection Examples
3820 Apply default values:
3822 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3826 Enable additional sharpening:
3832 Paint processed pixels in white:
3838 @section lut, lutrgb, lutyuv
3840 Compute a look-up table for binding each pixel component input value
3841 to an output value, and apply it to input video.
3843 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3844 to an RGB input video.
3846 These filters accept the following options:
3849 set first pixel component expression
3851 set second pixel component expression
3853 set third pixel component expression
3855 set fourth pixel component expression, corresponds to the alpha component
3858 set red component expression
3860 set green component expression
3862 set blue component expression
3864 alpha component expression
3867 set Y/luminance component expression
3869 set U/Cb component expression
3871 set V/Cr component expression
3874 Each of them specifies the expression to use for computing the lookup table for
3875 the corresponding pixel component values.
3877 The exact component associated to each of the @var{c*} options depends on the
3880 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3881 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3883 The expressions can contain the following constants and functions:
3887 the input width and height
3890 input value for the pixel component
3893 the input value clipped in the @var{minval}-@var{maxval} range
3896 maximum value for the pixel component
3899 minimum value for the pixel component
3902 the negated value for the pixel component value clipped in the
3903 @var{minval}-@var{maxval} range , it corresponds to the expression
3904 "maxval-clipval+minval"
3907 the computed value in @var{val} clipped in the
3908 @var{minval}-@var{maxval} range
3910 @item gammaval(gamma)
3911 the computed gamma correction value of the pixel component value
3912 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3914 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3918 All expressions default to "val".
3920 @subsection Examples
3926 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3927 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3930 The above is the same as:
3932 lutrgb="r=negval:g=negval:b=negval"
3933 lutyuv="y=negval:u=negval:v=negval"
3943 Remove chroma components, turns the video into a graytone image:
3945 lutyuv="u=128:v=128"
3949 Apply a luma burning effect:
3955 Remove green and blue components:
3961 Set a constant alpha channel value on input:
3963 format=rgba,lutrgb=a="maxval-minval/2"
3967 Correct luminance gamma by a 0.5 factor:
3969 lutyuv=y=gammaval(0.5)
3973 Discard least significant bits of luma:
3975 lutyuv=y='bitand(val, 128+64+32)'
3981 Apply an MPlayer filter to the input video.
3983 This filter provides a wrapper around most of the filters of
3986 This wrapper is considered experimental. Some of the wrapped filters
3987 may not work properly and we may drop support for them, as they will
3988 be implemented natively into FFmpeg. Thus you should avoid
3989 depending on them when writing portable scripts.
3991 The filters accepts the parameters:
3992 @var{filter_name}[:=]@var{filter_params}
3994 @var{filter_name} is the name of a supported MPlayer filter,
3995 @var{filter_params} is a string containing the parameters accepted by
3998 The list of the currently supported filters follows:
4025 The parameter syntax and behavior for the listed filters are the same
4026 of the corresponding MPlayer filters. For detailed instructions check
4027 the "VIDEO FILTERS" section in the MPlayer manual.
4029 @subsection Examples
4033 Adjust gamma, brightness, contrast:
4039 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4045 This filter accepts an integer in input, if non-zero it negates the
4046 alpha component (if available). The default value in input is 0.
4050 Force libavfilter not to use any of the specified pixel formats for the
4051 input to the next filter.
4053 This filter accepts the following parameters:
4057 A '|'-separated list of pixel format names, for example
4058 "pix_fmts=yuv420p|monow|rgb24".
4062 @subsection Examples
4066 Force libavfilter to use a format different from @var{yuv420p} for the
4067 input to the vflip filter:
4069 noformat=pix_fmts=yuv420p,vflip
4073 Convert the input video to any of the formats not contained in the list:
4075 noformat=yuv420p|yuv444p|yuv410p
4081 Add noise on video input frame.
4083 The filter accepts the following options:
4091 Set noise seed for specific pixel component or all pixel components in case
4092 of @var{all_seed}. Default value is @code{123457}.
4094 @item all_strength, alls
4095 @item c0_strength, c0s
4096 @item c1_strength, c1s
4097 @item c2_strength, c2s
4098 @item c3_strength, c3s
4099 Set noise strength for specific pixel component or all pixel components in case
4100 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4102 @item all_flags, allf
4107 Set pixel component flags or set flags for all components if @var{all_flags}.
4108 Available values for component flags are:
4111 averaged temporal noise (smoother)
4113 mix random noise with a (semi)regular pattern
4115 higher quality (slightly better looking, slightly slower)
4117 temporal noise (noise pattern changes between frames)
4119 uniform noise (gaussian otherwise)
4123 @subsection Examples
4125 Add temporal and uniform noise to input video:
4127 noise=alls=20:allf=t+u
4132 Pass the video source unchanged to the output.
4136 Apply video transform using libopencv.
4138 To enable this filter install libopencv library and headers and
4139 configure FFmpeg with @code{--enable-libopencv}.
4141 This filter accepts the following parameters:
4146 The name of the libopencv filter to apply.
4149 The parameters to pass to the libopencv filter. If not specified the default
4154 Refer to the official libopencv documentation for more precise
4156 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4158 Follows the list of supported libopencv filters.
4163 Dilate an image by using a specific structuring element.
4164 This filter corresponds to the libopencv function @code{cvDilate}.
4166 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4168 @var{struct_el} represents a structuring element, and has the syntax:
4169 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4171 @var{cols} and @var{rows} represent the number of columns and rows of
4172 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4173 point, and @var{shape} the shape for the structuring element, and
4174 can be one of the values "rect", "cross", "ellipse", "custom".
4176 If the value for @var{shape} is "custom", it must be followed by a
4177 string of the form "=@var{filename}". The file with name
4178 @var{filename} is assumed to represent a binary image, with each
4179 printable character corresponding to a bright pixel. When a custom
4180 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4181 or columns and rows of the read file are assumed instead.
4183 The default value for @var{struct_el} is "3x3+0x0/rect".
4185 @var{nb_iterations} specifies the number of times the transform is
4186 applied to the image, and defaults to 1.
4188 Follow some example:
4190 # use the default values
4193 # dilate using a structuring element with a 5x5 cross, iterate two times
4194 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4196 # read the shape from the file diamond.shape, iterate two times
4197 # the file diamond.shape may contain a pattern of characters like this:
4203 # the specified cols and rows are ignored (but not the anchor point coordinates)
4204 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4209 Erode an image by using a specific structuring element.
4210 This filter corresponds to the libopencv function @code{cvErode}.
4212 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4213 with the same syntax and semantics as the @ref{dilate} filter.
4217 Smooth the input video.
4219 The filter takes the following parameters:
4220 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4222 @var{type} is the type of smooth filter to apply, and can be one of
4223 the following values: "blur", "blur_no_scale", "median", "gaussian",
4224 "bilateral". The default value is "gaussian".
4226 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4227 parameters whose meanings depend on smooth type. @var{param1} and
4228 @var{param2} accept integer positive values or 0, @var{param3} and
4229 @var{param4} accept float values.
4231 The default value for @var{param1} is 3, the default value for the
4232 other parameters is 0.
4234 These parameters correspond to the parameters assigned to the
4235 libopencv function @code{cvSmooth}.
4240 Overlay one video on top of another.
4242 It takes two inputs and one output, the first input is the "main"
4243 video on which the second input is overlayed.
4245 This filter accepts the following parameters:
4247 A description of the accepted options follows.
4252 Set the expression for the x and y coordinates of the overlayed video
4253 on the main video. Default value is "0" for both expressions. In case
4254 the expression is invalid, it is set to a huge value (meaning that the
4255 overlay will not be displayed within the output visible area).
4258 Set the expression which enables the overlay. If the evaluation is
4259 different from 0, the overlay is displayed on top of the input
4260 frame. By default it is "1".
4263 Set when the expressions for @option{x}, @option{y}, and
4264 @option{enable} are evaluated.
4266 It accepts the following values:
4269 only evaluate expressions once during the filter initialization or
4270 when a command is processed
4273 evaluate expressions for each incoming frame
4276 Default value is @samp{frame}.
4279 If set to 1, force the output to terminate when the shortest input
4280 terminates. Default value is 0.
4283 Set the format for the output video.
4285 It accepts the following values:
4297 Default value is @samp{yuv420}.
4299 @item rgb @emph{(deprecated)}
4300 If set to 1, force the filter to accept inputs in the RGB
4301 color space. Default value is 0. This option is deprecated, use
4302 @option{format} instead.
4305 If set to 1, force the filter to draw the last overlay frame over the
4306 main input until the end of the stream. A value of 0 disables this
4307 behavior, which is enabled by default.
4310 The @option{x}, @option{y}, and @option{enable} expressions can
4311 contain the following parameters.
4316 main input width and height
4320 overlay input width and height
4324 the computed values for @var{x} and @var{y}. They are evaluated for
4329 horizontal and vertical chroma subsample values of the output
4330 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4334 the number of input frame, starting from 0
4337 the position in the file of the input frame, NAN if unknown
4340 timestamp expressed in seconds, NAN if the input timestamp is unknown
4343 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4344 when evaluation is done @emph{per frame}, and will evaluate to NAN
4345 when @option{eval} is set to @samp{init}.
4347 Be aware that frames are taken from each input video in timestamp
4348 order, hence, if their initial timestamps differ, it is a a good idea
4349 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4350 have them begin in the same zero timestamp, as it does the example for
4351 the @var{movie} filter.
4353 You can chain together more overlays but you should test the
4354 efficiency of such approach.
4356 @subsection Commands
4358 This filter supports the following commands:
4363 Modify the x/y and enable overlay of the overlay input.
4364 The command accepts the same syntax of the corresponding option.
4366 If the specified expression is not valid, it is kept at its current
4370 @subsection Examples
4374 Draw the overlay at 10 pixels from the bottom right corner of the main
4377 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4380 Using named options the example above becomes:
4382 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4386 Insert a transparent PNG logo in the bottom left corner of the input,
4387 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4389 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4393 Insert 2 different transparent PNG logos (second logo on bottom
4394 right corner) using the @command{ffmpeg} tool:
4396 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
4400 Add a transparent color layer on top of the main video, @code{WxH}
4401 must specify the size of the main input to the overlay filter:
4403 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4407 Play an original video and a filtered version (here with the deshake
4408 filter) side by side using the @command{ffplay} tool:
4410 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4413 The above command is the same as:
4415 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4419 Make a sliding overlay appearing from the left to the right top part of the
4420 screen starting since time 2:
4422 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4426 Compose output by putting two input videos side to side:
4428 ffmpeg -i left.avi -i right.avi -filter_complex "
4429 nullsrc=size=200x100 [background];
4430 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4431 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4432 [background][left] overlay=shortest=1 [background+left];
4433 [background+left][right] overlay=shortest=1:x=100 [left+right]
4438 Chain several overlays in cascade:
4440 nullsrc=s=200x200 [bg];
4441 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4442 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4443 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4444 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4445 [in3] null, [mid2] overlay=100:100 [out0]
4452 Add paddings to the input image, and place the original input at the
4453 given coordinates @var{x}, @var{y}.
4455 This filter accepts the following parameters:
4460 Specify an expression for the size of the output image with the
4461 paddings added. If the value for @var{width} or @var{height} is 0, the
4462 corresponding input size is used for the output.
4464 The @var{width} expression can reference the value set by the
4465 @var{height} expression, and vice versa.
4467 The default value of @var{width} and @var{height} is 0.
4471 Specify an expression for the offsets where to place the input image
4472 in the padded area with respect to the top/left border of the output
4475 The @var{x} expression can reference the value set by the @var{y}
4476 expression, and vice versa.
4478 The default value of @var{x} and @var{y} is 0.
4481 Specify the color of the padded area, it can be the name of a color
4482 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4484 The default value of @var{color} is "black".
4487 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4488 options are expressions containing the following constants:
4492 the input video width and height
4495 same as @var{in_w} and @var{in_h}
4498 the output width and height, that is the size of the padded area as
4499 specified by the @var{width} and @var{height} expressions
4502 same as @var{out_w} and @var{out_h}
4505 x and y offsets as specified by the @var{x} and @var{y}
4506 expressions, or NAN if not yet specified
4509 same as @var{iw} / @var{ih}
4512 input sample aspect ratio
4515 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4518 horizontal and vertical chroma subsample values. For example for the
4519 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4522 @subsection Examples
4526 Add paddings with color "violet" to the input video. Output video
4527 size is 640x480, the top-left corner of the input video is placed at
4530 pad=640:480:0:40:violet
4533 The example above is equivalent to the following command:
4535 pad=width=640:height=480:x=0:y=40:color=violet
4539 Pad the input to get an output with dimensions increased by 3/2,
4540 and put the input video at the center of the padded area:
4542 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4546 Pad the input to get a squared output with size equal to the maximum
4547 value between the input width and height, and put the input video at
4548 the center of the padded area:
4550 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4554 Pad the input to get a final w/h ratio of 16:9:
4556 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4560 In case of anamorphic video, in order to set the output display aspect
4561 correctly, it is necessary to use @var{sar} in the expression,
4562 according to the relation:
4564 (ih * X / ih) * sar = output_dar
4565 X = output_dar / sar
4568 Thus the previous example needs to be modified to:
4570 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4574 Double output size and put the input video in the bottom-right
4575 corner of the output padded area:
4577 pad="2*iw:2*ih:ow-iw:oh-ih"
4581 @section pixdesctest
4583 Pixel format descriptor test filter, mainly useful for internal
4584 testing. The output video should be equal to the input video.
4588 format=monow, pixdesctest
4591 can be used to test the monowhite pixel format descriptor definition.
4595 Enable the specified chain of postprocessing subfilters using libpostproc. This
4596 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4597 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4598 Each subfilter and some options have a short and a long name that can be used
4599 interchangeably, i.e. dr/dering are the same.
4601 The filters accept the following options:
4605 Set postprocessing subfilters string.
4608 All subfilters share common options to determine their scope:
4612 Honor the quality commands for this subfilter.
4615 Do chrominance filtering, too (default).
4618 Do luminance filtering only (no chrominance).
4621 Do chrominance filtering only (no luminance).
4624 These options can be appended after the subfilter name, separated by a '|'.
4626 Available subfilters are:
4629 @item hb/hdeblock[|difference[|flatness]]
4630 Horizontal deblocking filter
4633 Difference factor where higher values mean more deblocking (default: @code{32}).
4635 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4638 @item vb/vdeblock[|difference[|flatness]]
4639 Vertical deblocking filter
4642 Difference factor where higher values mean more deblocking (default: @code{32}).
4644 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4647 @item ha/hadeblock[|difference[|flatness]]
4648 Accurate horizontal deblocking filter
4651 Difference factor where higher values mean more deblocking (default: @code{32}).
4653 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4656 @item va/vadeblock[|difference[|flatness]]
4657 Accurate vertical deblocking filter
4660 Difference factor where higher values mean more deblocking (default: @code{32}).
4662 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4666 The horizontal and vertical deblocking filters share the difference and
4667 flatness values so you cannot set different horizontal and vertical
4672 Experimental horizontal deblocking filter
4675 Experimental vertical deblocking filter
4680 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4683 larger -> stronger filtering
4685 larger -> stronger filtering
4687 larger -> stronger filtering
4690 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4693 Stretch luminance to @code{0-255}.
4696 @item lb/linblenddeint
4697 Linear blend deinterlacing filter that deinterlaces the given block by
4698 filtering all lines with a @code{(1 2 1)} filter.
4700 @item li/linipoldeint
4701 Linear interpolating deinterlacing filter that deinterlaces the given block by
4702 linearly interpolating every second line.
4704 @item ci/cubicipoldeint
4705 Cubic interpolating deinterlacing filter deinterlaces the given block by
4706 cubically interpolating every second line.
4708 @item md/mediandeint
4709 Median deinterlacing filter that deinterlaces the given block by applying a
4710 median filter to every second line.
4712 @item fd/ffmpegdeint
4713 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4714 second line with a @code{(-1 4 2 4 -1)} filter.
4717 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4718 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4720 @item fq/forceQuant[|quantizer]
4721 Overrides the quantizer table from the input with the constant quantizer you
4729 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4732 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4735 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4738 @subsection Examples
4742 Apply horizontal and vertical deblocking, deringing and automatic
4743 brightness/contrast:
4749 Apply default filters without brightness/contrast correction:
4755 Apply default filters and temporal denoiser:
4757 pp=default/tmpnoise|1|2|3
4761 Apply deblocking on luminance only, and switch vertical deblocking on or off
4762 automatically depending on available CPU time:
4770 Suppress a TV station logo, using an image file to determine which
4771 pixels comprise the logo. It works by filling in the pixels that
4772 comprise the logo with neighboring pixels.
4774 The filters accept the following options:
4778 Set the filter bitmap file, which can be any image format supported by
4779 libavformat. The width and height of the image file must match those of the
4780 video stream being processed.
4783 Pixels in the provided bitmap image with a value of zero are not
4784 considered part of the logo, non-zero pixels are considered part of
4785 the logo. If you use white (255) for the logo and black (0) for the
4786 rest, you will be safe. For making the filter bitmap, it is
4787 recommended to take a screen capture of a black frame with the logo
4788 visible, and then using a threshold filter followed by the erode
4789 filter once or twice.
4791 If needed, little splotches can be fixed manually. Remember that if
4792 logo pixels are not covered, the filter quality will be much
4793 reduced. Marking too many pixels as part of the logo does not hurt as
4794 much, but it will increase the amount of blurring needed to cover over
4795 the image and will destroy more information than necessary, and extra
4796 pixels will slow things down on a large logo.
4800 Scale (resize) the input video, using the libswscale library.
4802 The scale filter forces the output display aspect ratio to be the same
4803 of the input, by changing the output sample aspect ratio.
4805 The filter accepts the following options:
4810 default value is @code{iw}. See below
4811 for the list of accepted constants.
4814 Output video height.
4815 default value is @code{ih}.
4816 See below for the list of accepted constants.
4819 Set the interlacing. It accepts the following values:
4823 force interlaced aware scaling
4826 do not apply interlaced scaling
4829 select interlaced aware scaling depending on whether the source frames
4830 are flagged as interlaced or not
4833 Default value is @code{0}.
4836 Set libswscale scaling flags. If not explictly specified the filter
4837 applies a bilinear scaling algorithm.
4840 Set the video size, the value must be a valid abbreviation or in the
4841 form @var{width}x@var{height}.
4844 The values of the @var{w} and @var{h} options are expressions
4845 containing the following constants:
4849 the input width and height
4852 same as @var{in_w} and @var{in_h}
4855 the output (cropped) width and height
4858 same as @var{out_w} and @var{out_h}
4861 same as @var{iw} / @var{ih}
4864 input sample aspect ratio
4867 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4870 horizontal and vertical chroma subsample values. For example for the
4871 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4874 If the input image format is different from the format requested by
4875 the next filter, the scale filter will convert the input to the
4878 If the value for @var{w} or @var{h} is 0, the respective input
4879 size is used for the output.
4881 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4882 respective output size, a value that maintains the aspect ratio of the input
4885 @subsection Examples
4889 Scale the input video to a size of 200x100:
4894 This is equivalent to:
4905 Specify a size abbreviation for the output size:
4910 which can also be written as:
4916 Scale the input to 2x:
4922 The above is the same as:
4928 Scale the input to 2x with forced interlaced scaling:
4930 scale=2*iw:2*ih:interl=1
4934 Scale the input to half size:
4940 Increase the width, and set the height to the same size:
4946 Seek for Greek harmony:
4953 Increase the height, and set the width to 3/2 of the height:
4955 scale=w=3/2*oh:h=3/5*ih
4959 Increase the size, but make the size a multiple of the chroma
4962 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4966 Increase the width to a maximum of 500 pixels, keep the same input
4969 scale=w='min(500\, iw*3/2):h=-1'
4973 @section separatefields
4975 The @code{separatefields} takes a frame-based video input and splits
4976 each frame into its components fields, producing a new half height clip
4977 with twice the frame rate and twice the frame count.
4979 This filter use field-dominance information in frame to decide which
4980 of each pair of fields to place first in the output.
4981 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
4983 @section setdar, setsar
4985 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4988 This is done by changing the specified Sample (aka Pixel) Aspect
4989 Ratio, according to the following equation:
4991 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4994 Keep in mind that the @code{setdar} filter does not modify the pixel
4995 dimensions of the video frame. Also the display aspect ratio set by
4996 this filter may be changed by later filters in the filterchain,
4997 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5000 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5001 the filter output video.
5003 Note that as a consequence of the application of this filter, the
5004 output display aspect ratio will change according to the equation
5007 Keep in mind that the sample aspect ratio set by the @code{setsar}
5008 filter may be changed by later filters in the filterchain, e.g. if
5009 another "setsar" or a "setdar" filter is applied.
5011 The filters accept the following options:
5014 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
5015 Set the aspect ratio used by the filter.
5017 The parameter can be a floating point number string, an expression, or
5018 a string of the form @var{num}:@var{den}, where @var{num} and
5019 @var{den} are the numerator and denominator of the aspect ratio. If
5020 the parameter is not specified, it is assumed the value "0".
5021 In case the form "@var{num}:@var{den}" the @code{:} character should
5025 Set the maximum integer value to use for expressing numerator and
5026 denominator when reducing the expressed aspect ratio to a rational.
5027 Default value is @code{100}.
5031 @subsection Examples
5036 To change the display aspect ratio to 16:9, specify one of the following:
5044 To change the sample aspect ratio to 10:11, specify:
5050 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5051 1000 in the aspect ratio reduction, use the command:
5053 setdar=ratio=16/9:max=1000
5061 Force field for the output video frame.
5063 The @code{setfield} filter marks the interlace type field for the
5064 output frames. It does not change the input frame, but only sets the
5065 corresponding property, which affects how the frame is treated by
5066 following filters (e.g. @code{fieldorder} or @code{yadif}).
5068 The filter accepts the following options:
5073 Available values are:
5077 Keep the same field property.
5080 Mark the frame as bottom-field-first.
5083 Mark the frame as top-field-first.
5086 Mark the frame as progressive.
5092 Show a line containing various information for each input video frame.
5093 The input video is not modified.
5095 The shown line contains a sequence of key/value pairs of the form
5096 @var{key}:@var{value}.
5098 A description of each shown parameter follows:
5102 sequential number of the input frame, starting from 0
5105 Presentation TimeStamp of the input frame, expressed as a number of
5106 time base units. The time base unit depends on the filter input pad.
5109 Presentation TimeStamp of the input frame, expressed as a number of
5113 position of the frame in the input stream, -1 if this information in
5114 unavailable and/or meaningless (for example in case of synthetic video)
5120 sample aspect ratio of the input frame, expressed in the form
5124 size of the input frame, expressed in the form
5125 @var{width}x@var{height}
5128 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5129 for bottom field first)
5132 1 if the frame is a key frame, 0 otherwise
5135 picture type of the input frame ("I" for an I-frame, "P" for a
5136 P-frame, "B" for a B-frame, "?" for unknown type).
5137 Check also the documentation of the @code{AVPictureType} enum and of
5138 the @code{av_get_picture_type_char} function defined in
5139 @file{libavutil/avutil.h}.
5142 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5144 @item plane_checksum
5145 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5146 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5151 Blur the input video without impacting the outlines.
5153 The filter accepts the following options:
5156 @item luma_radius, lr
5157 Set the luma radius. The option value must be a float number in
5158 the range [0.1,5.0] that specifies the variance of the gaussian filter
5159 used to blur the image (slower if larger). Default value is 1.0.
5161 @item luma_strength, ls
5162 Set the luma strength. The option value must be a float number
5163 in the range [-1.0,1.0] that configures the blurring. A value included
5164 in [0.0,1.0] will blur the image whereas a value included in
5165 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5167 @item luma_threshold, lt
5168 Set the luma threshold used as a coefficient to determine
5169 whether a pixel should be blurred or not. The option value must be an
5170 integer in the range [-30,30]. A value of 0 will filter all the image,
5171 a value included in [0,30] will filter flat areas and a value included
5172 in [-30,0] will filter edges. Default value is 0.
5174 @item chroma_radius, cr
5175 Set the chroma radius. The option value must be a float number in
5176 the range [0.1,5.0] that specifies the variance of the gaussian filter
5177 used to blur the image (slower if larger). Default value is 1.0.
5179 @item chroma_strength, cs
5180 Set the chroma strength. The option value must be a float number
5181 in the range [-1.0,1.0] that configures the blurring. A value included
5182 in [0.0,1.0] will blur the image whereas a value included in
5183 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5185 @item chroma_threshold, ct
5186 Set the chroma threshold used as a coefficient to determine
5187 whether a pixel should be blurred or not. The option value must be an
5188 integer in the range [-30,30]. A value of 0 will filter all the image,
5189 a value included in [0,30] will filter flat areas and a value included
5190 in [-30,0] will filter edges. Default value is 0.
5193 If a chroma option is not explicitly set, the corresponding luma value
5198 Convert between different stereoscopic image formats.
5200 The filters accept the following options:
5204 Set stereoscopic image format of input.
5206 Available values for input image formats are:
5209 side by side parallel (left eye left, right eye right)
5212 side by side crosseye (right eye left, left eye right)
5215 side by side parallel with half width resolution
5216 (left eye left, right eye right)
5219 side by side crosseye with half width resolution
5220 (right eye left, left eye right)
5223 above-below (left eye above, right eye below)
5226 above-below (right eye above, left eye below)
5229 above-below with half height resolution
5230 (left eye above, right eye below)
5233 above-below with half height resolution
5234 (right eye above, left eye below)
5236 Default value is @samp{sbsl}.
5240 Set stereoscopic image format of output.
5242 Available values for output image formats are all the input formats as well as:
5245 anaglyph red/blue gray
5246 (red filter on left eye, blue filter on right eye)
5249 anaglyph red/green gray
5250 (red filter on left eye, green filter on right eye)
5253 anaglyph red/cyan gray
5254 (red filter on left eye, cyan filter on right eye)
5257 anaglyph red/cyan half colored
5258 (red filter on left eye, cyan filter on right eye)
5261 anaglyph red/cyan color
5262 (red filter on left eye, cyan filter on right eye)
5265 anaglyph red/cyan color optimized with the least squares projection of dubois
5266 (red filter on left eye, cyan filter on right eye)
5269 anaglyph green/magenta gray
5270 (green filter on left eye, magenta filter on right eye)
5273 anaglyph green/magenta half colored
5274 (green filter on left eye, magenta filter on right eye)
5277 anaglyph green/magenta colored
5278 (green filter on left eye, magenta filter on right eye)
5281 anaglyph green/magenta color optimized with the least squares projection of dubois
5282 (green filter on left eye, magenta filter on right eye)
5285 anaglyph yellow/blue gray
5286 (yellow filter on left eye, blue filter on right eye)
5289 anaglyph yellow/blue half colored
5290 (yellow filter on left eye, blue filter on right eye)
5293 anaglyph yellow/blue colored
5294 (yellow filter on left eye, blue filter on right eye)
5297 anaglyph yellow/blue color optimized with the least squares projection of dubois
5298 (yellow filter on left eye, blue filter on right eye)
5301 interleaved rows (left eye has top row, right eye starts on next row)
5304 interleaved rows (right eye has top row, left eye starts on next row)
5307 mono output (left eye only)
5310 mono output (right eye only)
5313 Default value is @samp{arcd}.
5319 Draw subtitles on top of input video using the libass library.
5321 To enable compilation of this filter you need to configure FFmpeg with
5322 @code{--enable-libass}. This filter also requires a build with libavcodec and
5323 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5324 Alpha) subtitles format.
5326 The filter accepts the following options:
5330 Set the filename of the subtitle file to read. It must be specified.
5333 Specify the size of the original video, the video for which the ASS file
5334 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5335 necessary to correctly scale the fonts if the aspect ratio has been changed.
5338 Set subtitles input character encoding. @code{subtitles} filter only. Only
5339 useful if not UTF-8.
5342 If the first key is not specified, it is assumed that the first value
5343 specifies the @option{filename}.
5345 For example, to render the file @file{sub.srt} on top of the input
5346 video, use the command:
5351 which is equivalent to:
5353 subtitles=filename=sub.srt
5358 Split input video into several identical outputs.
5360 The filter accepts a single parameter which specifies the number of outputs. If
5361 unspecified, it defaults to 2.
5365 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5367 will create 5 copies of the input video.
5371 [in] split [splitout1][splitout2];
5372 [splitout1] crop=100:100:0:0 [cropout];
5373 [splitout2] pad=200:200:100:100 [padout];
5376 will create two separate outputs from the same input, one cropped and
5381 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5382 Interpolate) pixel art scaling algorithm.
5384 Useful for enlarging pixel art images without reducing sharpness.
5390 Select the most representative frame in a given sequence of consecutive frames.
5392 The filter accepts the following options:
5396 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5397 will pick one of them, and then handle the next batch of @var{n} frames until
5398 the end. Default is @code{100}.
5401 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5402 value will result in a higher memory usage, so a high value is not recommended.
5404 @subsection Examples
5408 Extract one picture each 50 frames:
5414 Complete example of a thumbnail creation with @command{ffmpeg}:
5416 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5422 Tile several successive frames together.
5424 The filter accepts the following options:
5429 Set the grid size (i.e. the number of lines and columns) in the form
5433 Set the maximum number of frames to render in the given area. It must be less
5434 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5435 the area will be used.
5438 Set the outer border margin in pixels.
5441 Set the inner border thickness (i.e. the number of pixels between frames). For
5442 more advanced padding options (such as having different values for the edges),
5443 refer to the pad video filter.
5447 @subsection Examples
5451 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5453 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5455 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5456 duplicating each output frame to accomodate the originally detected frame
5460 Display @code{5} pictures in an area of @code{3x2} frames,
5461 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5462 mixed flat and named options:
5464 tile=3x2:nb_frames=5:padding=7:margin=2
5470 Perform various types of temporal field interlacing.
5472 Frames are counted starting from 1, so the first input frame is
5475 The filter accepts the following options:
5480 Specify the mode of the interlacing. This option can also be specified
5481 as a value alone. See below for a list of values for this option.
5483 Available values are:
5487 Move odd frames into the upper field, even into the lower field,
5488 generating a double height frame at half frame rate.
5491 Only output even frames, odd frames are dropped, generating a frame with
5492 unchanged height at half frame rate.
5495 Only output odd frames, even frames are dropped, generating a frame with
5496 unchanged height at half frame rate.
5499 Expand each frame to full height, but pad alternate lines with black,
5500 generating a frame with double height at the same input frame rate.
5502 @item interleave_top, 4
5503 Interleave the upper field from odd frames with the lower field from
5504 even frames, generating a frame with unchanged height at half frame rate.
5506 @item interleave_bottom, 5
5507 Interleave the lower field from odd frames with the upper field from
5508 even frames, generating a frame with unchanged height at half frame rate.
5510 @item interlacex2, 6
5511 Double frame rate with unchanged height. Frames are inserted each
5512 containing the second temporal field from the previous input frame and
5513 the first temporal field from the next input frame. This mode relies on
5514 the top_field_first flag. Useful for interlaced video displays with no
5515 field synchronisation.
5518 Numeric values are deprecated but are accepted for backward
5519 compatibility reasons.
5521 Default mode is @code{merge}.
5524 Specify flags influencing the filter process.
5526 Available value for @var{flags} is:
5529 @item low_pass_filter, vlfp
5530 Enable vertical low-pass filtering in the filter.
5531 Vertical low-pass filtering is required when creating an interlaced
5532 destination from a progressive source which contains high-frequency
5533 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5536 Vertical low-pass filtering can only be enabled for @option{mode}
5537 @var{interleave_top} and @var{interleave_bottom}.
5544 Transpose rows with columns in the input video and optionally flip it.
5546 This filter accepts the following options:
5551 The direction of the transpose.
5554 @item 0, 4, cclock_flip
5555 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5563 Rotate by 90 degrees clockwise, that is:
5571 Rotate by 90 degrees counterclockwise, that is:
5578 @item 3, 7, clock_flip
5579 Rotate by 90 degrees clockwise and vertically flip, that is:
5587 For values between 4-7, the transposition is only done if the input
5588 video geometry is portrait and not landscape. These values are
5589 deprecated, the @code{passthrough} option should be used instead.
5592 Do not apply the transposition if the input geometry matches the one
5593 specified by the specified value. It accepts the following values:
5596 Always apply transposition.
5598 Preserve portrait geometry (when @var{height} >= @var{width}).
5600 Preserve landscape geometry (when @var{width} >= @var{height}).
5603 Default value is @code{none}.
5606 For example to rotate by 90 degrees clockwise and preserve portrait
5609 transpose=dir=1:passthrough=portrait
5612 The command above can also be specified as:
5614 transpose=1:portrait
5619 Sharpen or blur the input video.
5621 It accepts the following parameters:
5624 @item luma_msize_x, lx
5625 @item chroma_msize_x, cx
5626 Set the luma/chroma matrix horizontal size. It must be an odd integer
5627 between 3 and 63, default value is 5.
5629 @item luma_msize_y, ly
5630 @item chroma_msize_y, cy
5631 Set the luma/chroma matrix vertical size. It must be an odd integer
5632 between 3 and 63, default value is 5.
5634 @item luma_amount, la
5635 @item chroma_amount, ca
5636 Set the luma/chroma effect strength. It can be a float number,
5637 reasonable values lay between -1.5 and 1.5.
5639 Negative values will blur the input video, while positive values will
5640 sharpen it, a value of zero will disable the effect.
5642 Default value is 1.0 for @option{luma_amount}, 0.0 for
5643 @option{chroma_amount}.
5646 All parameters are optional and default to the
5647 equivalent of the string '5:5:1.0:5:5:0.0'.
5649 @subsection Examples
5653 Apply strong luma sharpen effect:
5655 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5659 Apply strong blur of both luma and chroma parameters:
5661 unsharp=7:7:-2:7:7:-2
5667 Flip the input video vertically.
5670 ffmpeg -i in.avi -vf "vflip" out.avi
5675 Deinterlace the input video ("yadif" means "yet another deinterlacing
5678 This filter accepts the following options:
5684 The interlacing mode to adopt, accepts one of the following values:
5688 output 1 frame for each frame
5690 output 1 frame for each field
5691 @item 2, send_frame_nospatial
5692 like @code{send_frame} but skip spatial interlacing check
5693 @item 3, send_field_nospatial
5694 like @code{send_field} but skip spatial interlacing check
5697 Default value is @code{send_frame}.
5700 The picture field parity assumed for the input interlaced video, accepts one of
5701 the following values:
5705 assume top field first
5707 assume bottom field first
5709 enable automatic detection
5712 Default value is @code{auto}.
5713 If interlacing is unknown or decoder does not export this information,
5714 top field first will be assumed.
5717 Specify which frames to deinterlace. Accept one of the following
5722 deinterlace all frames
5724 only deinterlace frames marked as interlaced
5727 Default value is @code{all}.
5730 @c man end VIDEO FILTERS
5732 @chapter Video Sources
5733 @c man begin VIDEO SOURCES
5735 Below is a description of the currently available video sources.
5739 Buffer video frames, and make them available to the filter chain.
5741 This source is mainly intended for a programmatic use, in particular
5742 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5744 This source accepts the following options:
5749 Specify the size (width and height) of the buffered video frames.
5758 A string representing the pixel format of the buffered video frames.
5759 It may be a number corresponding to a pixel format, or a pixel format
5763 Specify the timebase assumed by the timestamps of the buffered frames.
5766 Specify the frame rate expected for the video stream.
5768 @item pixel_aspect, sar
5769 Specify the sample aspect ratio assumed by the video frames.
5772 Specify the optional parameters to be used for the scale filter which
5773 is automatically inserted when an input change is detected in the
5774 input size or format.
5779 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
5782 will instruct the source to accept video frames with size 320x240 and
5783 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5784 square pixels (1:1 sample aspect ratio).
5785 Since the pixel format with name "yuv410p" corresponds to the number 6
5786 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5787 this example corresponds to:
5789 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5792 Alternatively, the options can be specified as a flat string, but this
5793 syntax is deprecated:
5795 @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}]
5799 Create a pattern generated by an elementary cellular automaton.
5801 The initial state of the cellular automaton can be defined through the
5802 @option{filename}, and @option{pattern} options. If such options are
5803 not specified an initial state is created randomly.
5805 At each new frame a new row in the video is filled with the result of
5806 the cellular automaton next generation. The behavior when the whole
5807 frame is filled is defined by the @option{scroll} option.
5809 This source accepts the following options:
5813 Read the initial cellular automaton state, i.e. the starting row, from
5815 In the file, each non-whitespace character is considered an alive
5816 cell, a newline will terminate the row, and further characters in the
5817 file will be ignored.
5820 Read the initial cellular automaton state, i.e. the starting row, from
5821 the specified string.
5823 Each non-whitespace character in the string is considered an alive
5824 cell, a newline will terminate the row, and further characters in the
5825 string will be ignored.
5828 Set the video rate, that is the number of frames generated per second.
5831 @item random_fill_ratio, ratio
5832 Set the random fill ratio for the initial cellular automaton row. It
5833 is a floating point number value ranging from 0 to 1, defaults to
5836 This option is ignored when a file or a pattern is specified.
5838 @item random_seed, seed
5839 Set the seed for filling randomly the initial row, must be an integer
5840 included between 0 and UINT32_MAX. If not specified, or if explicitly
5841 set to -1, the filter will try to use a good random seed on a best
5845 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5846 Default value is 110.
5849 Set the size of the output video.
5851 If @option{filename} or @option{pattern} is specified, the size is set
5852 by default to the width of the specified initial state row, and the
5853 height is set to @var{width} * PHI.
5855 If @option{size} is set, it must contain the width of the specified
5856 pattern string, and the specified pattern will be centered in the
5859 If a filename or a pattern string is not specified, the size value
5860 defaults to "320x518" (used for a randomly generated initial state).
5863 If set to 1, scroll the output upward when all the rows in the output
5864 have been already filled. If set to 0, the new generated row will be
5865 written over the top row just after the bottom row is filled.
5868 @item start_full, full
5869 If set to 1, completely fill the output with generated rows before
5870 outputting the first frame.
5871 This is the default behavior, for disabling set the value to 0.
5874 If set to 1, stitch the left and right row edges together.
5875 This is the default behavior, for disabling set the value to 0.
5878 @subsection Examples
5882 Read the initial state from @file{pattern}, and specify an output of
5885 cellauto=f=pattern:s=200x400
5889 Generate a random initial row with a width of 200 cells, with a fill
5892 cellauto=ratio=2/3:s=200x200
5896 Create a pattern generated by rule 18 starting by a single alive cell
5897 centered on an initial row with width 100:
5899 cellauto=p=@@:s=100x400:full=0:rule=18
5903 Specify a more elaborated initial pattern:
5905 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5912 Generate a Mandelbrot set fractal, and progressively zoom towards the
5913 point specified with @var{start_x} and @var{start_y}.
5915 This source accepts the following options:
5920 Set the terminal pts value. Default value is 400.
5923 Set the terminal scale value.
5924 Must be a floating point value. Default value is 0.3.
5927 Set the inner coloring mode, that is the algorithm used to draw the
5928 Mandelbrot fractal internal region.
5930 It shall assume one of the following values:
5935 Show time until convergence.
5937 Set color based on point closest to the origin of the iterations.
5942 Default value is @var{mincol}.
5945 Set the bailout value. Default value is 10.0.
5948 Set the maximum of iterations performed by the rendering
5949 algorithm. Default value is 7189.
5952 Set outer coloring mode.
5953 It shall assume one of following values:
5955 @item iteration_count
5956 Set iteration cound mode.
5957 @item normalized_iteration_count
5958 set normalized iteration count mode.
5960 Default value is @var{normalized_iteration_count}.
5963 Set frame rate, expressed as number of frames per second. Default
5967 Set frame size. Default value is "640x480".
5970 Set the initial scale value. Default value is 3.0.
5973 Set the initial x position. Must be a floating point value between
5974 -100 and 100. Default value is -0.743643887037158704752191506114774.
5977 Set the initial y position. Must be a floating point value between
5978 -100 and 100. Default value is -0.131825904205311970493132056385139.
5983 Generate various test patterns, as generated by the MPlayer test filter.
5985 The size of the generated video is fixed, and is 256x256.
5986 This source is useful in particular for testing encoding features.
5988 This source accepts the following options:
5993 Specify the frame rate of the sourced video, as the number of frames
5994 generated per second. It has to be a string in the format
5995 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5996 number or a valid video frame rate abbreviation. The default value is
6000 Set the video duration of the sourced video. The accepted syntax is:
6005 See also the function @code{av_parse_time()}.
6007 If not specified, or the expressed duration is negative, the video is
6008 supposed to be generated forever.
6012 Set the number or the name of the test to perform. Supported tests are:
6027 Default value is "all", which will cycle through the list of all tests.
6030 For example the following:
6035 will generate a "dc_luma" test pattern.
6039 Provide a frei0r source.
6041 To enable compilation of this filter you need to install the frei0r
6042 header and configure FFmpeg with @code{--enable-frei0r}.
6044 This source accepts the following options:
6049 The size of the video to generate, may be a string of the form
6050 @var{width}x@var{height} or a frame size abbreviation.
6053 Framerate of the generated video, may be a string of the form
6054 @var{num}/@var{den} or a frame rate abbreviation.
6057 The name to the frei0r source to load. For more information regarding frei0r and
6058 how to set the parameters read the section @ref{frei0r} in the description of
6062 A '|'-separated list of parameters to pass to the frei0r source.
6066 For example, to generate a frei0r partik0l source with size 200x200
6067 and frame rate 10 which is overlayed on the overlay filter main input:
6069 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6074 Generate a life pattern.
6076 This source is based on a generalization of John Conway's life game.
6078 The sourced input represents a life grid, each pixel represents a cell
6079 which can be in one of two possible states, alive or dead. Every cell
6080 interacts with its eight neighbours, which are the cells that are
6081 horizontally, vertically, or diagonally adjacent.
6083 At each interaction the grid evolves according to the adopted rule,
6084 which specifies the number of neighbor alive cells which will make a
6085 cell stay alive or born. The @option{rule} option allows to specify
6088 This source accepts the following options:
6092 Set the file from which to read the initial grid state. In the file,
6093 each non-whitespace character is considered an alive cell, and newline
6094 is used to delimit the end of each row.
6096 If this option is not specified, the initial grid is generated
6100 Set the video rate, that is the number of frames generated per second.
6103 @item random_fill_ratio, ratio
6104 Set the random fill ratio for the initial random grid. It is a
6105 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6106 It is ignored when a file is specified.
6108 @item random_seed, seed
6109 Set the seed for filling the initial random grid, must be an integer
6110 included between 0 and UINT32_MAX. If not specified, or if explicitly
6111 set to -1, the filter will try to use a good random seed on a best
6117 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6118 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6119 @var{NS} specifies the number of alive neighbor cells which make a
6120 live cell stay alive, and @var{NB} the number of alive neighbor cells
6121 which make a dead cell to become alive (i.e. to "born").
6122 "s" and "b" can be used in place of "S" and "B", respectively.
6124 Alternatively a rule can be specified by an 18-bits integer. The 9
6125 high order bits are used to encode the next cell state if it is alive
6126 for each number of neighbor alive cells, the low order bits specify
6127 the rule for "borning" new cells. Higher order bits encode for an
6128 higher number of neighbor cells.
6129 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6130 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6132 Default value is "S23/B3", which is the original Conway's game of life
6133 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6134 cells, and will born a new cell if there are three alive cells around
6138 Set the size of the output video.
6140 If @option{filename} is specified, the size is set by default to the
6141 same size of the input file. If @option{size} is set, it must contain
6142 the size specified in the input file, and the initial grid defined in
6143 that file is centered in the larger resulting area.
6145 If a filename is not specified, the size value defaults to "320x240"
6146 (used for a randomly generated initial grid).
6149 If set to 1, stitch the left and right grid edges together, and the
6150 top and bottom edges also. Defaults to 1.
6153 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6154 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6155 value from 0 to 255.
6158 Set the color of living (or new born) cells.
6161 Set the color of dead cells. If @option{mold} is set, this is the first color
6162 used to represent a dead cell.
6165 Set mold color, for definitely dead and moldy cells.
6168 @subsection Examples
6172 Read a grid from @file{pattern}, and center it on a grid of size
6175 life=f=pattern:s=300x300
6179 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6181 life=ratio=2/3:s=200x200
6185 Specify a custom rule for evolving a randomly generated grid:
6191 Full example with slow death effect (mold) using @command{ffplay}:
6193 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6197 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6199 The @code{color} source provides an uniformly colored input.
6201 The @code{nullsrc} source returns unprocessed video frames. It is
6202 mainly useful to be employed in analysis / debugging tools, or as the
6203 source for filters which ignore the input data.
6205 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6206 detecting RGB vs BGR issues. You should see a red, green and blue
6207 stripe from top to bottom.
6209 The @code{smptebars} source generates a color bars pattern, based on
6210 the SMPTE Engineering Guideline EG 1-1990.
6212 The @code{testsrc} source generates a test video pattern, showing a
6213 color pattern, a scrolling gradient and a timestamp. This is mainly
6214 intended for testing purposes.
6216 The sources accept the following options:
6221 Specify the color of the source, only used in the @code{color}
6222 source. It can be the name of a color (case insensitive match) or a
6223 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6224 default value is "black".
6227 Specify the size of the sourced video, it may be a string of the form
6228 @var{width}x@var{height}, or the name of a size abbreviation. The
6229 default value is "320x240".
6232 Specify the frame rate of the sourced video, as the number of frames
6233 generated per second. It has to be a string in the format
6234 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6235 number or a valid video frame rate abbreviation. The default value is
6239 Set the sample aspect ratio of the sourced video.
6242 Set the video duration of the sourced video. The accepted syntax is:
6244 [-]HH[:MM[:SS[.m...]]]
6247 See also the function @code{av_parse_time()}.
6249 If not specified, or the expressed duration is negative, the video is
6250 supposed to be generated forever.
6253 Set the number of decimals to show in the timestamp, only used in the
6254 @code{testsrc} source.
6256 The displayed timestamp value will correspond to the original
6257 timestamp value multiplied by the power of 10 of the specified
6258 value. Default value is 0.
6261 For example the following:
6263 testsrc=duration=5.3:size=qcif:rate=10
6266 will generate a video with a duration of 5.3 seconds, with size
6267 176x144 and a frame rate of 10 frames per second.
6269 The following graph description will generate a red source
6270 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6273 color=c=red@@0.2:s=qcif:r=10
6276 If the input content is to be ignored, @code{nullsrc} can be used. The
6277 following command generates noise in the luminance plane by employing
6278 the @code{geq} filter:
6280 nullsrc=s=256x256, geq=random(1)*255:128:128
6283 @c man end VIDEO SOURCES
6285 @chapter Video Sinks
6286 @c man begin VIDEO SINKS
6288 Below is a description of the currently available video sinks.
6292 Buffer video frames, and make them available to the end of the filter
6295 This sink is mainly intended for a programmatic use, in particular
6296 through the interface defined in @file{libavfilter/buffersink.h}
6297 or the options system.
6299 It accepts a pointer to an AVBufferSinkContext structure, which
6300 defines the incoming buffers' formats, to be passed as the opaque
6301 parameter to @code{avfilter_init_filter} for initialization.
6305 Null video sink, do absolutely nothing with the input video. It is
6306 mainly useful as a template and to be employed in analysis / debugging
6309 @c man end VIDEO SINKS
6311 @chapter Multimedia Filters
6312 @c man begin MULTIMEDIA FILTERS
6314 Below is a description of the currently available multimedia filters.
6316 @section aperms, perms
6318 Set read/write permissions for the output frames.
6320 These filters are mainly aimed at developers to test direct path in the
6321 following filter in the filtergraph.
6323 The filters accept the following options:
6327 Select the permissions mode.
6329 It accepts the following values:
6332 Do nothing. This is the default.
6334 Set all the output frames read-only.
6336 Set all the output frames directly writable.
6338 Make the frame read-only if writable, and writable if read-only.
6340 Set each output frame read-only or writable randomly.
6344 Set the seed for the @var{random} mode, must be an integer included between
6345 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6346 @code{-1}, the filter will try to use a good random seed on a best effort
6350 Note: in case of auto-inserted filter between the permission filter and the
6351 following one, the permission might not be received as expected in that
6352 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6353 perms/aperms filter can avoid this problem.
6356 Add a phasing effect to the input audio.
6358 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6359 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6361 A description of the accepted parameters follows.
6365 Set input gain. Default is 0.4.
6368 Set output gain. Default is 0.74
6371 Set delay in milliseconds. Default is 3.0.
6374 Set decay. Default is 0.4.
6377 Set modulation speed in Hz. Default is 0.5.
6380 Set modulation type. Default is triangular.
6382 It accepts the following values:
6389 @section aselect, select
6390 Select frames to pass in output.
6392 This filter accepts the following options:
6397 An expression, which is evaluated for each input frame. If the expression is
6398 evaluated to a non-zero value, the frame is selected and passed to the output,
6399 otherwise it is discarded.
6403 The expression can contain the following constants:
6407 the sequential number of the filtered frame, starting from 0
6410 the sequential number of the selected frame, starting from 0
6412 @item prev_selected_n
6413 the sequential number of the last selected frame, NAN if undefined
6416 timebase of the input timestamps
6419 the PTS (Presentation TimeStamp) of the filtered video frame,
6420 expressed in @var{TB} units, NAN if undefined
6423 the PTS (Presentation TimeStamp) of the filtered video frame,
6424 expressed in seconds, NAN if undefined
6427 the PTS of the previously filtered video frame, NAN if undefined
6429 @item prev_selected_pts
6430 the PTS of the last previously filtered video frame, NAN if undefined
6432 @item prev_selected_t
6433 the PTS of the last previously selected video frame, NAN if undefined
6436 the PTS of the first video frame in the video, NAN if undefined
6439 the time of the first video frame in the video, NAN if undefined
6441 @item pict_type @emph{(video only)}
6442 the type of the filtered frame, can assume one of the following
6454 @item interlace_type @emph{(video only)}
6455 the frame interlace type, can assume one of the following values:
6458 the frame is progressive (not interlaced)
6460 the frame is top-field-first
6462 the frame is bottom-field-first
6465 @item consumed_sample_n @emph{(audio only)}
6466 the number of selected samples before the current frame
6468 @item samples_n @emph{(audio only)}
6469 the number of samples in the current frame
6471 @item sample_rate @emph{(audio only)}
6472 the input sample rate
6475 1 if the filtered frame is a key-frame, 0 otherwise
6478 the position in the file of the filtered frame, -1 if the information
6479 is not available (e.g. for synthetic video)
6481 @item scene @emph{(video only)}
6482 value between 0 and 1 to indicate a new scene; a low value reflects a low
6483 probability for the current frame to introduce a new scene, while a higher
6484 value means the current frame is more likely to be one (see the example below)
6488 The default value of the select expression is "1".
6490 @subsection Examples
6494 Select all frames in input:
6499 The example above is the same as:
6511 Select only I-frames:
6513 select='eq(pict_type\,I)'
6517 Select one frame every 100:
6519 select='not(mod(n\,100))'
6523 Select only frames contained in the 10-20 time interval:
6525 select='gte(t\,10)*lte(t\,20)'
6529 Select only I frames contained in the 10-20 time interval:
6531 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6535 Select frames with a minimum distance of 10 seconds:
6537 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6541 Use aselect to select only audio frames with samples number > 100:
6543 aselect='gt(samples_n\,100)'
6547 Create a mosaic of the first scenes:
6549 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6552 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6556 @section asendcmd, sendcmd
6558 Send commands to filters in the filtergraph.
6560 These filters read commands to be sent to other filters in the
6563 @code{asendcmd} must be inserted between two audio filters,
6564 @code{sendcmd} must be inserted between two video filters, but apart
6565 from that they act the same way.
6567 The specification of commands can be provided in the filter arguments
6568 with the @var{commands} option, or in a file specified by the
6569 @var{filename} option.
6571 These filters accept the following options:
6574 Set the commands to be read and sent to the other filters.
6576 Set the filename of the commands to be read and sent to the other
6580 @subsection Commands syntax
6582 A commands description consists of a sequence of interval
6583 specifications, comprising a list of commands to be executed when a
6584 particular event related to that interval occurs. The occurring event
6585 is typically the current frame time entering or leaving a given time
6588 An interval is specified by the following syntax:
6590 @var{START}[-@var{END}] @var{COMMANDS};
6593 The time interval is specified by the @var{START} and @var{END} times.
6594 @var{END} is optional and defaults to the maximum time.
6596 The current frame time is considered within the specified interval if
6597 it is included in the interval [@var{START}, @var{END}), that is when
6598 the time is greater or equal to @var{START} and is lesser than
6601 @var{COMMANDS} consists of a sequence of one or more command
6602 specifications, separated by ",", relating to that interval. The
6603 syntax of a command specification is given by:
6605 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6608 @var{FLAGS} is optional and specifies the type of events relating to
6609 the time interval which enable sending the specified command, and must
6610 be a non-null sequence of identifier flags separated by "+" or "|" and
6611 enclosed between "[" and "]".
6613 The following flags are recognized:
6616 The command is sent when the current frame timestamp enters the
6617 specified interval. In other words, the command is sent when the
6618 previous frame timestamp was not in the given interval, and the
6622 The command is sent when the current frame timestamp leaves the
6623 specified interval. In other words, the command is sent when the
6624 previous frame timestamp was in the given interval, and the
6628 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6631 @var{TARGET} specifies the target of the command, usually the name of
6632 the filter class or a specific filter instance name.
6634 @var{COMMAND} specifies the name of the command for the target filter.
6636 @var{ARG} is optional and specifies the optional list of argument for
6637 the given @var{COMMAND}.
6639 Between one interval specification and another, whitespaces, or
6640 sequences of characters starting with @code{#} until the end of line,
6641 are ignored and can be used to annotate comments.
6643 A simplified BNF description of the commands specification syntax
6646 @var{COMMAND_FLAG} ::= "enter" | "leave"
6647 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6648 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6649 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6650 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6651 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6654 @subsection Examples
6658 Specify audio tempo change at second 4:
6660 asendcmd=c='4.0 atempo tempo 1.5',atempo
6664 Specify a list of drawtext and hue commands in a file.
6666 # show text in the interval 5-10
6667 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6668 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6670 # desaturate the image in the interval 15-20
6671 15.0-20.0 [enter] hue s 0,
6672 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6674 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6676 # apply an exponential saturation fade-out effect, starting from time 25
6677 25 [enter] hue s exp(25-t)
6680 A filtergraph allowing to read and process the above command list
6681 stored in a file @file{test.cmd}, can be specified with:
6683 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6688 @section asetpts, setpts
6690 Change the PTS (presentation timestamp) of the input frames.
6692 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6694 This filter accepts the following options:
6699 The expression which is evaluated for each frame to construct its timestamp.
6703 The expression is evaluated through the eval API and can contain the following
6708 frame rate, only defined for constant frame-rate video
6711 the presentation timestamp in input
6714 the count of the input frame, starting from 0.
6716 @item NB_CONSUMED_SAMPLES
6717 the number of consumed samples, not including the current frame (only
6721 the number of samples in the current frame (only audio)
6727 the PTS of the first frame
6730 the time in seconds of the first frame
6733 tell if the current frame is interlaced
6736 the time in seconds of the current frame
6742 original position in the file of the frame, or undefined if undefined
6743 for the current frame
6749 previous input time in seconds
6755 previous output time in seconds
6758 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6762 wallclock (RTC) time at the start of the movie in microseconds
6765 @subsection Examples
6769 Start counting PTS from zero
6775 Apply fast motion effect:
6781 Apply slow motion effect:
6787 Set fixed rate of 25 frames per second:
6793 Set fixed rate 25 fps with some jitter:
6795 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6799 Apply an offset of 10 seconds to the input PTS:
6805 Generate timestamps from a "live source" and rebase onto the current timebase:
6807 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6813 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6814 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6815 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6816 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6818 The filter also has a video output (see the @var{video} option) with a real
6819 time graph to observe the loudness evolution. The graphic contains the logged
6820 message mentioned above, so it is not printed anymore when this option is set,
6821 unless the verbose logging is set. The main graphing area contains the
6822 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6823 the momentary loudness (400 milliseconds).
6825 More information about the Loudness Recommendation EBU R128 on
6826 @url{http://tech.ebu.ch/loudness}.
6828 The filter accepts the following options:
6833 Activate the video output. The audio stream is passed unchanged whether this
6834 option is set or no. The video stream will be the first output stream if
6835 activated. Default is @code{0}.
6838 Set the video size. This option is for video only. Default and minimum
6839 resolution is @code{640x480}.
6842 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6843 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6844 other integer value between this range is allowed.
6847 Set metadata injection. If set to @code{1}, the audio input will be segmented
6848 into 100ms output frames, each of them containing various loudness information
6849 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6851 Default is @code{0}.
6854 Force the frame logging level.
6856 Available values are:
6859 information logging level
6861 verbose logging level
6864 By default, the logging level is set to @var{info}. If the @option{video} or
6865 the @option{metadata} options are set, it switches to @var{verbose}.
6868 @subsection Examples
6872 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6874 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6878 Run an analysis with @command{ffmpeg}:
6880 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6884 @section settb, asettb
6886 Set the timebase to use for the output frames timestamps.
6887 It is mainly useful for testing timebase configuration.
6889 This filter accepts the following options:
6894 The expression which is evaluated into the output timebase.
6898 The value for @option{tb} is an arithmetic expression representing a
6899 rational. The expression can contain the constants "AVTB" (the default
6900 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6901 audio only). Default value is "intb".
6903 @subsection Examples
6907 Set the timebase to 1/25:
6913 Set the timebase to 1/10:
6919 Set the timebase to 1001/1000:
6925 Set the timebase to 2*intb:
6931 Set the default timebase value:
6939 Concatenate audio and video streams, joining them together one after the
6942 The filter works on segments of synchronized video and audio streams. All
6943 segments must have the same number of streams of each type, and that will
6944 also be the number of streams at output.
6946 The filter accepts the following options:
6951 Set the number of segments. Default is 2.
6954 Set the number of output video streams, that is also the number of video
6955 streams in each segment. Default is 1.
6958 Set the number of output audio streams, that is also the number of video
6959 streams in each segment. Default is 0.
6962 Activate unsafe mode: do not fail if segments have a different format.
6966 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6967 @var{a} audio outputs.
6969 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6970 segment, in the same order as the outputs, then the inputs for the second
6973 Related streams do not always have exactly the same duration, for various
6974 reasons including codec frame size or sloppy authoring. For that reason,
6975 related synchronized streams (e.g. a video and its audio track) should be
6976 concatenated at once. The concat filter will use the duration of the longest
6977 stream in each segment (except the last one), and if necessary pad shorter
6978 audio streams with silence.
6980 For this filter to work correctly, all segments must start at timestamp 0.
6982 All corresponding streams must have the same parameters in all segments; the
6983 filtering system will automatically select a common pixel format for video
6984 streams, and a common sample format, sample rate and channel layout for
6985 audio streams, but other settings, such as resolution, must be converted
6986 explicitly by the user.
6988 Different frame rates are acceptable but will result in variable frame rate
6989 at output; be sure to configure the output file to handle it.
6991 @subsection Examples
6995 Concatenate an opening, an episode and an ending, all in bilingual version
6996 (video in stream 0, audio in streams 1 and 2):
6998 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6999 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7000 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7001 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7005 Concatenate two parts, handling audio and video separately, using the
7006 (a)movie sources, and adjusting the resolution:
7008 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7009 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7010 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7012 Note that a desync will happen at the stitch if the audio and video streams
7013 do not have exactly the same duration in the first file.
7017 @section showspectrum
7019 Convert input audio to a video output, representing the audio frequency
7022 The filter accepts the following options:
7026 Specify the video size for the output. Default value is @code{640x512}.
7029 Specify if the spectrum should slide along the window. Default value is
7033 Specify display mode.
7035 It accepts the following values:
7038 all channels are displayed in the same row
7040 all channels are displayed in separate rows
7043 Default value is @samp{combined}.
7046 Specify display color mode.
7048 It accepts the following values:
7051 each channel is displayed in a separate color
7053 each channel is is displayed using the same color scheme
7056 Default value is @samp{channel}.
7059 Specify scale used for calculating intensity color values.
7061 It accepts the following values:
7066 square root, default
7073 Default value is @samp{sqrt}.
7076 Set saturation modifier for displayed colors. Negative values provide
7077 alternative color scheme. @code{0} is no saturation at all.
7078 Saturation must be in [-10.0, 10.0] range.
7079 Default value is @code{1}.
7082 The usage is very similar to the showwaves filter; see the examples in that
7085 @subsection Examples
7089 Large window with logarithmic color scaling:
7091 showspectrum=s=1280x480:scale=log
7095 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7097 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7098 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7104 Convert input audio to a video output, representing the samples waves.
7106 The filter accepts the following options:
7110 Specify the video size for the output. Default value is "600x240".
7115 Available values are:
7118 Draw a point for each sample.
7121 Draw a vertical line for each sample.
7124 Default value is @code{point}.
7127 Set the number of samples which are printed on the same column. A
7128 larger value will decrease the frame rate. Must be a positive
7129 integer. This option can be set only if the value for @var{rate}
7130 is not explicitly specified.
7133 Set the (approximate) output frame rate. This is done by setting the
7134 option @var{n}. Default value is "25".
7138 @subsection Examples
7142 Output the input file audio and the corresponding video representation
7145 amovie=a.mp3,asplit[out0],showwaves[out1]
7149 Create a synthetic signal and show it with showwaves, forcing a
7150 frame rate of 30 frames per second:
7152 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7156 @c man end MULTIMEDIA FILTERS
7158 @chapter Multimedia Sources
7159 @c man begin MULTIMEDIA SOURCES
7161 Below is a description of the currently available multimedia sources.
7165 This is the same as @ref{movie} source, except it selects an audio
7171 Read audio and/or video stream(s) from a movie container.
7173 This filter accepts the following options:
7177 The name of the resource to read (not necessarily a file but also a device or a
7178 stream accessed through some protocol).
7180 @item format_name, f
7181 Specifies the format assumed for the movie to read, and can be either
7182 the name of a container or an input device. If not specified the
7183 format is guessed from @var{movie_name} or by probing.
7185 @item seek_point, sp
7186 Specifies the seek point in seconds, the frames will be output
7187 starting from this seek point, the parameter is evaluated with
7188 @code{av_strtod} so the numerical value may be suffixed by an IS
7189 postfix. Default value is "0".
7192 Specifies the streams to read. Several streams can be specified,
7193 separated by "+". The source will then have as many outputs, in the
7194 same order. The syntax is explained in the ``Stream specifiers''
7195 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7196 respectively the default (best suited) video and audio stream. Default
7197 is "dv", or "da" if the filter is called as "amovie".
7199 @item stream_index, si
7200 Specifies the index of the video stream to read. If the value is -1,
7201 the best suited video stream will be automatically selected. Default
7202 value is "-1". Deprecated. If the filter is called "amovie", it will select
7203 audio instead of video.
7206 Specifies how many times to read the stream in sequence.
7207 If the value is less than 1, the stream will be read again and again.
7208 Default value is "1".
7210 Note that when the movie is looped the source timestamps are not
7211 changed, so it will generate non monotonically increasing timestamps.
7214 This filter allows to overlay a second video on top of main input of
7215 a filtergraph as shown in this graph:
7217 input -----------> deltapts0 --> overlay --> output
7220 movie --> scale--> deltapts1 -------+
7223 @subsection Examples
7227 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7228 on top of the input labelled as "in":
7230 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7231 [in] setpts=PTS-STARTPTS [main];
7232 [main][over] overlay=16:16 [out]
7236 Read from a video4linux2 device, and overlay it on top of the input
7239 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7240 [in] setpts=PTS-STARTPTS [main];
7241 [main][over] overlay=16:16 [out]
7245 Read the first video stream and the audio stream with id 0x81 from
7246 dvd.vob; the video is connected to the pad named "video" and the audio is
7247 connected to the pad named "audio":
7249 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7253 @c man end MULTIMEDIA SOURCES