1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 This filtergraph splits the input stream in two streams, sends one
19 stream through the crop filter and the vflip filter before merging it
20 back with the other stream by overlaying it on top. You can use the
21 following command to achieve this:
24 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
27 The result will be that in output the top half of the video is mirrored
30 Filters in the same linear chain are separated by commas, and distinct
31 linear chains of filters are separated by semicolons. In our example,
32 @var{crop,vflip} are in one linear chain, @var{split} and
33 @var{overlay} are separately in another. The points where the linear
34 chains join are labelled by names enclosed in square brackets. In the
35 example, the split filter generates two outputs that are associated to
36 the labels @var{[main]} and @var{[tmp]}.
38 The stream sent to the second output of @var{split}, labelled as
39 @var{[tmp]}, is processed through the @var{crop} filter, which crops
40 away the lower half part of the video, and then vertically flipped. The
41 @var{overlay} filter takes in input the first unchanged output of the
42 split filter (which was labelled as @var{[main]}), and overlay on its
43 lower half the output generated by the @var{crop,vflip} filterchain.
45 Some filters take in input a list of parameters: they are specified
46 after the filter name and an equal sign, and are separated from each other
49 There exist so-called @var{source filters} that do not have an
50 audio/video input, and @var{sink filters} that will not have audio/video
53 @c man end FILTERING INTRODUCTION
56 @c man begin GRAPH2DOT
58 The @file{graph2dot} program included in the FFmpeg @file{tools}
59 directory can be used to parse a filtergraph description and issue a
60 corresponding textual representation in the dot language.
67 to see how to use @file{graph2dot}.
69 You can then pass the dot description to the @file{dot} program (from
70 the graphviz suite of programs) and obtain a graphical representation
73 For example the sequence of commands:
75 echo @var{GRAPH_DESCRIPTION} | \
76 tools/graph2dot -o graph.tmp && \
77 dot -Tpng graph.tmp -o graph.png && \
81 can be used to create and display an image representing the graph
82 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
83 a complete self-contained graph, with its inputs and outputs explicitly defined.
84 For example if your command line is of the form:
86 ffmpeg -i infile -vf scale=640:360 outfile
88 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
90 nullsrc,scale=640:360,nullsink
92 you may also need to set the @var{nullsrc} parameters and add a @var{format}
93 filter in order to simulate a specific input file.
97 @chapter Filtergraph description
98 @c man begin FILTERGRAPH DESCRIPTION
100 A filtergraph is a directed graph of connected filters. It can contain
101 cycles, and there can be multiple links between a pair of
102 filters. Each link has one input pad on one side connecting it to one
103 filter from which it takes its input, and one output pad on the other
104 side connecting it to the one filter accepting its output.
106 Each filter in a filtergraph is an instance of a filter class
107 registered in the application, which defines the features and the
108 number of input and output pads of the filter.
110 A filter with no input pads is called a "source", a filter with no
111 output pads is called a "sink".
113 @anchor{Filtergraph syntax}
114 @section Filtergraph syntax
116 A filtergraph can be represented using a textual representation, which is
117 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
118 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
119 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
120 @file{libavfilter/avfiltergraph.h}.
122 A filterchain consists of a sequence of connected filters, each one
123 connected to the previous one in the sequence. A filterchain is
124 represented by a list of ","-separated filter descriptions.
126 A filtergraph consists of a sequence of filterchains. A sequence of
127 filterchains is represented by a list of ";"-separated filterchain
130 A filter is represented by a string of the form:
131 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
133 @var{filter_name} is the name of the filter class of which the
134 described filter is an instance of, and has to be the name of one of
135 the filter classes registered in the program.
136 The name of the filter class is optionally followed by a string
139 @var{arguments} is a string which contains the parameters used to
140 initialize the filter instance. It may have one of the following forms:
144 A ':'-separated list of @var{key=value} pairs.
147 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
148 the option names in the order they are declared. E.g. the @code{fade} filter
149 declares three options in this order -- @option{type}, @option{start_frame} and
150 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
151 @var{in} is assigned to the option @option{type}, @var{0} to
152 @option{start_frame} and @var{30} to @option{nb_frames}.
155 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
156 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
157 follow the same constraints order of the previous point. The following
158 @var{key=value} pairs can be set in any preferred order.
162 If the option value itself is a list of items (e.g. the @code{format} filter
163 takes a list of pixel formats), the items in the list are usually separated by
166 The list of arguments can be quoted using the character "'" as initial
167 and ending mark, and the character '\' for escaping the characters
168 within the quoted text; otherwise the argument string is considered
169 terminated when the next special character (belonging to the set
170 "[]=;,") is encountered.
172 The name and arguments of the filter are optionally preceded and
173 followed by a list of link labels.
174 A link label allows to name a link and associate it to a filter output
175 or input pad. The preceding labels @var{in_link_1}
176 ... @var{in_link_N}, are associated to the filter input pads,
177 the following labels @var{out_link_1} ... @var{out_link_M}, are
178 associated to the output pads.
180 When two link labels with the same name are found in the
181 filtergraph, a link between the corresponding input and output pad is
184 If an output pad is not labelled, it is linked by default to the first
185 unlabelled input pad of the next filter in the filterchain.
186 For example in the filterchain:
188 nullsrc, split[L1], [L2]overlay, nullsink
190 the split filter instance has two output pads, and the overlay filter
191 instance two input pads. The first output pad of split is labelled
192 "L1", the first input pad of overlay is labelled "L2", and the second
193 output pad of split is linked to the second input pad of overlay,
194 which are both unlabelled.
196 In a complete filterchain all the unlabelled filter input and output
197 pads must be connected. A filtergraph is considered valid if all the
198 filter input and output pads of all the filterchains are connected.
200 Libavfilter will automatically insert scale filters where format
201 conversion is required. It is possible to specify swscale flags
202 for those automatically inserted scalers by prepending
203 @code{sws_flags=@var{flags};}
204 to the filtergraph description.
206 Follows a BNF description for the filtergraph syntax:
208 @var{NAME} ::= sequence of alphanumeric characters and '_'
209 @var{LINKLABEL} ::= "[" @var{NAME} "]"
210 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
211 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
212 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
213 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
214 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
217 @section Notes on filtergraph escaping
219 Some filter arguments require the use of special characters, typically
220 @code{:} to separate key=value pairs in a named options list. In this
221 case the user should perform a first level escaping when specifying
222 the filter arguments. For example, consider the following literal
223 string to be embedded in the @ref{drawtext} filter arguments:
225 this is a 'string': may contain one, or more, special characters
228 Since @code{:} is special for the filter arguments syntax, it needs to
229 be escaped, so you get:
231 text=this is a \'string\'\: may contain one, or more, special characters
234 A second level of escaping is required when embedding the filter
235 arguments in a filtergraph description, in order to escape all the
236 filtergraph special characters. Thus the example above becomes:
238 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
241 Finally an additional level of escaping may be needed when writing the
242 filtergraph description in a shell command, which depends on the
243 escaping rules of the adopted shell. For example, assuming that
244 @code{\} is special and needs to be escaped with another @code{\}, the
245 previous string will finally result in:
247 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
250 Sometimes, it might be more convenient to employ quoting in place of
251 escaping. For example the string:
253 Caesar: tu quoque, Brute, fili mi
256 Can be quoted in the filter arguments as:
258 text='Caesar: tu quoque, Brute, fili mi'
261 And finally inserted in a filtergraph like:
263 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
266 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
267 for more information about the escaping and quoting rules adopted by
270 @c man end FILTERGRAPH DESCRIPTION
272 @chapter Audio Filters
273 @c man begin AUDIO FILTERS
275 When you configure your FFmpeg build, you can disable any of the
276 existing filters using @code{--disable-filters}.
277 The configure output will show the audio filters included in your
280 Below is a description of the currently available audio filters.
284 Convert the input audio format to the specified formats.
286 The filter accepts a string of the form:
287 "@var{sample_format}:@var{channel_layout}".
289 @var{sample_format} specifies the sample format, and can be a string or the
290 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
291 suffix for a planar sample format.
293 @var{channel_layout} specifies the channel layout, and can be a string
294 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
296 The special parameter "auto", signifies that the filter will
297 automatically select the output format depending on the output filter.
303 Convert input to float, planar, stereo:
309 Convert input to unsigned 8-bit, automatically select out channel layout:
317 Apply a two-pole all-pass filter with central frequency (in Hz)
318 @var{frequency}, and filter-width @var{width}.
319 An all-pass filter changes the audio's frequency to phase relationship
320 without changing its frequency to amplitude relationship.
322 The filter accepts parameters as a list of @var{key}=@var{value}
323 pairs, separated by ":".
325 A description of the accepted parameters follows.
332 Set method to specify band-width of filter.
345 Specify the band-width of a filter in width_type units.
350 Apply a high-pass filter with 3dB point frequency.
351 The filter can be either single-pole, or double-pole (the default).
352 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
354 The filter accepts parameters as a list of @var{key}=@var{value}
355 pairs, separated by ":".
357 A description of the accepted parameters follows.
361 Set frequency in Hz. Default is 3000.
364 Set number of poles. Default is 2.
367 Set method to specify band-width of filter.
380 Specify the band-width of a filter in width_type units.
381 Applies only to double-pole filter.
382 The default is 0.707q and gives a Butterworth response.
387 Apply a low-pass filter with 3dB point frequency.
388 The filter can be either single-pole or double-pole (the default).
389 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
391 The filter accepts parameters as a list of @var{key}=@var{value}
392 pairs, separated by ":".
394 A description of the accepted parameters follows.
398 Set frequency in Hz. Default is 500.
401 Set number of poles. Default is 2.
404 Set method to specify band-width of filter.
417 Specify the band-width of a filter in width_type units.
418 Applies only to double-pole filter.
419 The default is 0.707q and gives a Butterworth response.
424 Boost or cut the bass (lower) frequencies of the audio using a two-pole
425 shelving filter with a response similar to that of a standard
426 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
428 The filter accepts parameters as a list of @var{key}=@var{value}
429 pairs, separated by ":".
431 A description of the accepted parameters follows.
435 Give the gain at 0 Hz. Its useful range is about -20
436 (for a large cut) to +20 (for a large boost).
437 Beware of clipping when using a positive gain.
440 Set the filter's central frequency and so can be used
441 to extend or reduce the frequency range to be boosted or cut.
442 The default value is @code{100} Hz.
445 Set method to specify band-width of filter.
458 Determine how steep is the filter's shelf transition.
463 Apply telecine process to the video.
465 This filter accepts the following options:
474 The default value is @code{top}.
478 A string of numbers representing the pulldown pattern you wish to apply.
479 The default value is @code{23}.
483 Some typical patterns:
488 24p: 2332 (preferred)
495 24p: 222222222223 ("Euro pulldown")
502 Boost or cut treble (upper) frequencies of the audio using a two-pole
503 shelving filter with a response similar to that of a standard
504 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
506 The filter accepts parameters as a list of @var{key}=@var{value}
507 pairs, separated by ":".
509 A description of the accepted parameters follows.
513 Give the gain at whichever is the lower of ~22 kHz and the
514 Nyquist frequency. Its useful range is about -20 (for a large cut)
515 to +20 (for a large boost). Beware of clipping when using a positive gain.
518 Set the filter's central frequency and so can be used
519 to extend or reduce the frequency range to be boosted or cut.
520 The default value is @code{3000} Hz.
523 Set method to specify band-width of filter.
536 Determine how steep is the filter's shelf transition.
541 Apply a two-pole Butterworth band-pass filter with central
542 frequency @var{frequency}, and (3dB-point) band-width width.
543 The @var{csg} option selects a constant skirt gain (peak gain = Q)
544 instead of the default: constant 0dB peak gain.
545 The filter roll off at 6dB per octave (20dB per decade).
547 The filter accepts parameters as a list of @var{key}=@var{value}
548 pairs, separated by ":".
550 A description of the accepted parameters follows.
554 Set the filter's central frequency. Default is @code{3000}.
557 Constant skirt gain if set to 1. Defaults to 0.
560 Set method to specify band-width of filter.
573 Specify the band-width of a filter in width_type units.
578 Apply a two-pole Butterworth band-reject filter with central
579 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
580 The filter roll off at 6dB per octave (20dB per decade).
582 The filter accepts parameters as a list of @var{key}=@var{value}
583 pairs, separated by ":".
585 A description of the accepted parameters follows.
589 Set the filter's central frequency. Default is @code{3000}.
592 Set method to specify band-width of filter.
605 Specify the band-width of a filter in width_type units.
610 Apply a biquad IIR filter with the given coefficients.
611 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
612 are the numerator and denominator coefficients respectively.
616 Apply a two-pole peaking equalisation (EQ) filter. With this
617 filter, the signal-level at and around a selected frequency can
618 be increased or decreased, whilst (unlike bandpass and bandreject
619 filters) that at all other frequencies is unchanged.
621 In order to produce complex equalisation curves, this filter can
622 be given several times, each with a different central frequency.
624 The filter accepts parameters as a list of @var{key}=@var{value}
625 pairs, separated by ":".
627 A description of the accepted parameters follows.
631 Set the filter's central frequency in Hz.
634 Set method to specify band-width of filter.
647 Specify the band-width of a filter in width_type units.
650 Set the required gain or attenuation in dB.
651 Beware of clipping when using a positive gain.
656 Apply fade-in/out effect to input audio.
658 A description of the accepted parameters follows.
662 Specify the effect type, can be either @code{in} for fade-in, or
663 @code{out} for a fade-out effect. Default is @code{in}.
665 @item start_sample, ss
666 Specify the number of the start sample for starting to apply the fade
667 effect. Default is 0.
670 Specify the number of samples for which the fade effect has to last. At
671 the end of the fade-in effect the output audio will have the same
672 volume as the input audio, at the end of the fade-out transition
673 the output audio will be silence. Default is 44100.
676 Specify time in seconds for starting to apply the fade
677 effect. Default is 0.
678 If set this option is used instead of @var{start_sample} one.
681 Specify the number of seconds for which the fade effect has to last. At
682 the end of the fade-in effect the output audio will have the same
683 volume as the input audio, at the end of the fade-out transition
684 the output audio will be silence. Default is 0.
685 If set this option is used instead of @var{nb_samples} one.
688 Set curve for fade transition.
690 It accepts the following values:
693 select triangular, linear slope (default)
695 select quarter of sine wave
697 select half of sine wave
699 select exponential sine wave
703 select inverted parabola
719 Fade in first 15 seconds of audio:
725 Fade out last 25 seconds of a 900 seconds audio:
727 afade=t=out:ss=875:d=25
734 Set output format constraints for the input audio. The framework will
735 negotiate the most appropriate format to minimize conversions.
737 The filter accepts the following named parameters:
741 A '|'-separated list of requested sample formats.
744 A '|'-separated list of requested sample rates.
746 @item channel_layouts
747 A '|'-separated list of requested channel layouts.
751 If a parameter is omitted, all values are allowed.
753 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
755 aformat=sample_fmts=u8|s16:channel_layouts=stereo
760 Merge two or more audio streams into a single multi-channel stream.
762 The filter accepts the following named options:
767 Set the number of inputs. Default is 2.
771 If the channel layouts of the inputs are disjoint, and therefore compatible,
772 the channel layout of the output will be set accordingly and the channels
773 will be reordered as necessary. If the channel layouts of the inputs are not
774 disjoint, the output will have all the channels of the first input then all
775 the channels of the second input, in that order, and the channel layout of
776 the output will be the default value corresponding to the total number of
779 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
780 is FC+BL+BR, then the output will be in 5.1, with the channels in the
781 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
782 first input, b1 is the first channel of the second input).
784 On the other hand, if both input are in stereo, the output channels will be
785 in the default order: a1, a2, b1, b2, and the channel layout will be
786 arbitrarily set to 4.0, which may or may not be the expected value.
788 All inputs must have the same sample rate, and format.
790 If inputs do not have the same duration, the output will stop with the
797 Merge two mono files into a stereo stream:
799 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
806 amovie=input.mkv:si=0 [a0];
807 amovie=input.mkv:si=1 [a1];
808 amovie=input.mkv:si=2 [a2];
809 amovie=input.mkv:si=3 [a3];
810 amovie=input.mkv:si=4 [a4];
811 amovie=input.mkv:si=5 [a5];
812 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
818 Mixes multiple audio inputs into a single output.
822 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
824 will mix 3 input audio streams to a single output with the same duration as the
825 first input and a dropout transition time of 3 seconds.
827 The filter accepts the following named parameters:
831 Number of inputs. If unspecified, it defaults to 2.
834 How to determine the end-of-stream.
838 Duration of longest input. (default)
841 Duration of shortest input.
844 Duration of first input.
848 @item dropout_transition
849 Transition time, in seconds, for volume renormalization when an input
850 stream ends. The default value is 2 seconds.
856 Pass the audio source unchanged to the output.
860 Pad the end of a audio stream with silence, this can be used together with
861 -shortest to extend audio streams to the same length as the video stream.
866 Resample the input audio to the specified parameters, using the
867 libswresample library. If none are specified then the filter will
868 automatically convert between its input and output.
870 This filter is also able to stretch/squeeze the audio data to make it match
871 the timestamps or to inject silence / cut out audio to make it match the
872 timestamps, do a combination of both or do neither.
874 The filter accepts the syntax
875 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
876 expresses a sample rate and @var{resampler_options} is a list of
877 @var{key}=@var{value} pairs, separated by ":". See the
878 ffmpeg-resampler manual for the complete list of supported options.
884 Resample the input audio to 44100Hz:
890 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
891 samples per second compensation:
897 @section asetnsamples
899 Set the number of samples per each output audio frame.
901 The last output packet may contain a different number of samples, as
902 the filter will flush all the remaining samples when the input audio
905 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
910 @item nb_out_samples, n
911 Set the number of frames per each output audio frame. The number is
912 intended as the number of samples @emph{per each channel}.
913 Default value is 1024.
916 If set to 1, the filter will pad the last audio frame with zeroes, so
917 that the last frame will contain the same number of samples as the
918 previous ones. Default value is 1.
921 For example, to set the number of per-frame samples to 1234 and
922 disable padding for the last frame, use:
924 asetnsamples=n=1234:p=0
929 Show a line containing various information for each input audio frame.
930 The input audio is not modified.
932 The shown line contains a sequence of key/value pairs of the form
933 @var{key}:@var{value}.
935 A description of each shown parameter follows:
939 sequential number of the input frame, starting from 0
942 Presentation timestamp of the input frame, in time base units; the time base
943 depends on the filter input pad, and is usually 1/@var{sample_rate}.
946 presentation timestamp of the input frame in seconds
949 position of the frame in the input stream, -1 if this information in
950 unavailable and/or meaningless (for example in case of synthetic audio)
959 sample rate for the audio frame
962 number of samples (per channel) in the frame
965 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
966 the data is treated as if all the planes were concatenated.
968 @item plane_checksums
969 A list of Adler-32 checksums for each data plane.
974 Split input audio into several identical outputs.
976 The filter accepts a single parameter which specifies the number of outputs. If
977 unspecified, it defaults to 2.
981 [in] asplit [out0][out1]
984 will create two separate outputs from the same input.
986 To create 3 or more outputs, you need to specify the number of
989 [in] asplit=3 [out0][out1][out2]
993 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
995 will create 5 copies of the input audio.
1000 Forward two audio streams and control the order the buffers are forwarded.
1002 The argument to the filter is an expression deciding which stream should be
1003 forwarded next: if the result is negative, the first stream is forwarded; if
1004 the result is positive or zero, the second stream is forwarded. It can use
1005 the following variables:
1009 number of buffers forwarded so far on each stream
1011 number of samples forwarded so far on each stream
1013 current timestamp of each stream
1016 The default value is @code{t1-t2}, which means to always forward the stream
1017 that has a smaller timestamp.
1019 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
1020 input, while avoiding too much of a desynchronization:
1022 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1023 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1031 The filter accepts exactly one parameter, the audio tempo. If not
1032 specified then the filter will assume nominal 1.0 tempo. Tempo must
1033 be in the [0.5, 2.0] range.
1035 @subsection Examples
1039 Slow down audio to 80% tempo:
1045 To speed up audio to 125% tempo:
1053 Make audio easier to listen to on headphones.
1055 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1056 so that when listened to on headphones the stereo image is moved from
1057 inside your head (standard for headphones) to outside and in front of
1058 the listener (standard for speakers).
1064 Mix channels with specific gain levels. The filter accepts the output
1065 channel layout followed by a set of channels definitions.
1067 This filter is also designed to remap efficiently the channels of an audio
1070 The filter accepts parameters of the form:
1071 "@var{l}:@var{outdef}:@var{outdef}:..."
1075 output channel layout or number of channels
1078 output channel specification, of the form:
1079 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1082 output channel to define, either a channel name (FL, FR, etc.) or a channel
1083 number (c0, c1, etc.)
1086 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1089 input channel to use, see out_name for details; it is not possible to mix
1090 named and numbered input channels
1093 If the `=' in a channel specification is replaced by `<', then the gains for
1094 that specification will be renormalized so that the total is 1, thus
1095 avoiding clipping noise.
1097 @subsection Mixing examples
1099 For example, if you want to down-mix from stereo to mono, but with a bigger
1100 factor for the left channel:
1102 pan=1:c0=0.9*c0+0.1*c1
1105 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1106 7-channels surround:
1108 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1111 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1112 that should be preferred (see "-ac" option) unless you have very specific
1115 @subsection Remapping examples
1117 The channel remapping will be effective if, and only if:
1120 @item gain coefficients are zeroes or ones,
1121 @item only one input per channel output,
1124 If all these conditions are satisfied, the filter will notify the user ("Pure
1125 channel mapping detected"), and use an optimized and lossless method to do the
1128 For example, if you have a 5.1 source and want a stereo audio stream by
1129 dropping the extra channels:
1131 pan="stereo: c0=FL : c1=FR"
1134 Given the same source, you can also switch front left and front right channels
1135 and keep the input channel layout:
1137 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1140 If the input is a stereo audio stream, you can mute the front left channel (and
1141 still keep the stereo channel layout) with:
1146 Still with a stereo audio stream input, you can copy the right channel in both
1147 front left and right:
1149 pan="stereo: c0=FR : c1=FR"
1152 @section silencedetect
1154 Detect silence in an audio stream.
1156 This filter logs a message when it detects that the input audio volume is less
1157 or equal to a noise tolerance value for a duration greater or equal to the
1158 minimum detected noise duration.
1160 The printed times and duration are expressed in seconds.
1162 The filter accepts the following options:
1166 Set silence duration until notification (default is 2 seconds).
1169 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1170 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1173 @subsection Examples
1177 Detect 5 seconds of silence with -50dB noise tolerance:
1179 silencedetect=n=-50dB:d=5
1183 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1184 tolerance in @file{silence.mp3}:
1186 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1191 Synchronize audio data with timestamps by squeezing/stretching it and/or
1192 dropping samples/adding silence when needed.
1194 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1196 The filter accepts the following named parameters:
1200 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1201 by default. When disabled, time gaps are covered with silence.
1204 Minimum difference between timestamps and audio data (in seconds) to trigger
1205 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1206 this filter, try setting this parameter to 0.
1209 Maximum compensation in samples per second. Relevant only with compensate=1.
1213 Assume the first pts should be this value. The time base is 1 / sample rate.
1214 This allows for padding/trimming at the start of stream. By default, no
1215 assumption is made about the first frame's expected pts, so no padding or
1216 trimming is done. For example, this could be set to 0 to pad the beginning with
1217 silence if an audio stream starts after the video stream or to trim any samples
1218 with a negative pts due to encoder delay.
1222 @section channelsplit
1223 Split each channel in input audio stream into a separate output stream.
1225 This filter accepts the following named parameters:
1227 @item channel_layout
1228 Channel layout of the input stream. Default is "stereo".
1231 For example, assuming a stereo input MP3 file
1233 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1235 will create an output Matroska file with two audio streams, one containing only
1236 the left channel and the other the right channel.
1238 To split a 5.1 WAV file into per-channel files
1240 ffmpeg -i in.wav -filter_complex
1241 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1242 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1243 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1248 Remap input channels to new locations.
1250 This filter accepts the following named parameters:
1252 @item channel_layout
1253 Channel layout of the output stream.
1256 Map channels from input to output. The argument is a '|'-separated list of
1257 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1258 @var{in_channel} form. @var{in_channel} can be either the name of the input
1259 channel (e.g. FL for front left) or its index in the input channel layout.
1260 @var{out_channel} is the name of the output channel or its index in the output
1261 channel layout. If @var{out_channel} is not given then it is implicitly an
1262 index, starting with zero and increasing by one for each mapping.
1265 If no mapping is present, the filter will implicitly map input channels to
1266 output channels preserving index.
1268 For example, assuming a 5.1+downmix input MOV file
1270 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1272 will create an output WAV file tagged as stereo from the downmix channels of
1275 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1277 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1281 Join multiple input streams into one multi-channel stream.
1283 The filter accepts the following named parameters:
1287 Number of input streams. Defaults to 2.
1289 @item channel_layout
1290 Desired output channel layout. Defaults to stereo.
1293 Map channels from inputs to output. The argument is a '|'-separated list of
1294 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1295 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1296 can be either the name of the input channel (e.g. FL for front left) or its
1297 index in the specified input stream. @var{out_channel} is the name of the output
1301 The filter will attempt to guess the mappings when those are not specified
1302 explicitly. It does so by first trying to find an unused matching input channel
1303 and if that fails it picks the first unused input channel.
1305 E.g. to join 3 inputs (with properly set channel layouts)
1307 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1310 To build a 5.1 output from 6 single-channel streams:
1312 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1313 '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'
1318 Convert the audio sample format, sample rate and channel layout. This filter is
1319 not meant to be used directly.
1323 Adjust the input audio volume.
1325 The filter accepts the following named parameters. If the key of the
1326 first options is omitted, the arguments are interpreted according to
1327 the following syntax:
1329 volume=@var{volume}:@var{precision}
1335 Expresses how the audio volume will be increased or decreased.
1337 Output values are clipped to the maximum value.
1339 The output audio volume is given by the relation:
1341 @var{output_volume} = @var{volume} * @var{input_volume}
1344 Default value for @var{volume} is 1.0.
1347 Set the mathematical precision.
1349 This determines which input sample formats will be allowed, which affects the
1350 precision of the volume scaling.
1354 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1356 32-bit floating-point; limits input sample format to FLT. (default)
1358 64-bit floating-point; limits input sample format to DBL.
1362 @subsection Examples
1366 Halve the input audio volume:
1370 volume=volume=-6.0206dB
1373 In all the above example the named key for @option{volume} can be
1374 omitted, for example like in:
1380 Increase input audio power by 6 decibels using fixed-point precision:
1382 volume=volume=6dB:precision=fixed
1386 @section volumedetect
1388 Detect the volume of the input video.
1390 The filter has no parameters. The input is not modified. Statistics about
1391 the volume will be printed in the log when the input stream end is reached.
1393 In particular it will show the mean volume (root mean square), maximum
1394 volume (on a per-sample basis), and the beginning of an histogram of the
1395 registered volume values (from the maximum value to a cumulated 1/1000 of
1398 All volumes are in decibels relative to the maximum PCM value.
1400 @subsection Examples
1402 Here is an excerpt of the output:
1404 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1405 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1406 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1407 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1408 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1409 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1410 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1411 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1412 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1418 The mean square energy is approximately -27 dB, or 10^-2.7.
1420 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1422 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1425 In other words, raising the volume by +4 dB does not cause any clipping,
1426 raising it by +5 dB causes clipping for 6 samples, etc.
1428 @c man end AUDIO FILTERS
1430 @chapter Audio Sources
1431 @c man begin AUDIO SOURCES
1433 Below is a description of the currently available audio sources.
1437 Buffer audio frames, and make them available to the filter chain.
1439 This source is mainly intended for a programmatic use, in particular
1440 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1442 It accepts the following mandatory parameters:
1443 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1448 The sample rate of the incoming audio buffers.
1451 The sample format of the incoming audio buffers.
1452 Either a sample format name or its corresponging integer representation from
1453 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1455 @item channel_layout
1456 The channel layout of the incoming audio buffers.
1457 Either a channel layout name from channel_layout_map in
1458 @file{libavutil/channel_layout.c} or its corresponding integer representation
1459 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1462 The number of channels of the incoming audio buffers.
1463 If both @var{channels} and @var{channel_layout} are specified, then they
1468 @subsection Examples
1471 abuffer=44100:s16p:stereo
1474 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1475 Since the sample format with name "s16p" corresponds to the number
1476 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1484 Generate an audio signal specified by an expression.
1486 This source accepts in input one or more expressions (one for each
1487 channel), which are evaluated and used to generate a corresponding
1490 It accepts the syntax: @var{exprs}[::@var{options}].
1491 @var{exprs} is a list of expressions separated by ":", one for each
1492 separate channel. In case the @var{channel_layout} is not
1493 specified, the selected channel layout depends on the number of
1494 provided expressions.
1496 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1499 The description of the accepted options follows.
1503 @item channel_layout, c
1504 Set the channel layout. The number of channels in the specified layout
1505 must be equal to the number of specified expressions.
1508 Set the minimum duration of the sourced audio. See the function
1509 @code{av_parse_time()} for the accepted format.
1510 Note that the resulting duration may be greater than the specified
1511 duration, as the generated audio is always cut at the end of a
1514 If not specified, or the expressed duration is negative, the audio is
1515 supposed to be generated forever.
1518 Set the number of samples per channel per each output frame,
1521 @item sample_rate, s
1522 Specify the sample rate, default to 44100.
1525 Each expression in @var{exprs} can contain the following constants:
1529 number of the evaluated sample, starting from 0
1532 time of the evaluated sample expressed in seconds, starting from 0
1539 @subsection Examples
1549 Generate a sin signal with frequency of 440 Hz, set sample rate to
1552 aevalsrc="sin(440*2*PI*t)::s=8000"
1556 Generate a two channels signal, specify the channel layout (Front
1557 Center + Back Center) explicitly:
1559 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1563 Generate white noise:
1565 aevalsrc="-2+random(0)"
1569 Generate an amplitude modulated signal:
1571 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1575 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1577 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1584 Null audio source, return unprocessed audio frames. It is mainly useful
1585 as a template and to be employed in analysis / debugging tools, or as
1586 the source for filters which ignore the input data (for example the sox
1589 It accepts an optional sequence of @var{key}=@var{value} pairs,
1592 The description of the accepted options follows.
1596 @item sample_rate, s
1597 Specify the sample rate, and defaults to 44100.
1599 @item channel_layout, cl
1601 Specify the channel layout, and can be either an integer or a string
1602 representing a channel layout. The default value of @var{channel_layout}
1605 Check the channel_layout_map definition in
1606 @file{libavutil/channel_layout.c} for the mapping between strings and
1607 channel layout values.
1610 Set the number of samples per requested frames.
1614 @subsection Examples
1618 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1620 anullsrc=r=48000:cl=4
1624 Do the same operation with a more obvious syntax:
1626 anullsrc=r=48000:cl=mono
1631 Buffer audio frames, and make them available to the filter chain.
1633 This source is not intended to be part of user-supplied graph descriptions but
1634 for insertion by calling programs through the interface defined in
1635 @file{libavfilter/buffersrc.h}.
1637 It accepts the following named parameters:
1641 Timebase which will be used for timestamps of submitted frames. It must be
1642 either a floating-point number or in @var{numerator}/@var{denominator} form.
1648 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1650 @item channel_layout
1651 Channel layout of the audio data, in the form that can be accepted by
1652 @code{av_get_channel_layout()}.
1655 All the parameters need to be explicitly defined.
1659 Synthesize a voice utterance using the libflite library.
1661 To enable compilation of this filter you need to configure FFmpeg with
1662 @code{--enable-libflite}.
1664 Note that the flite library is not thread-safe.
1666 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1669 The description of the accepted parameters follows.
1674 If set to 1, list the names of the available voices and exit
1675 immediately. Default value is 0.
1678 Set the maximum number of samples per frame. Default value is 512.
1681 Set the filename containing the text to speak.
1684 Set the text to speak.
1687 Set the voice to use for the speech synthesis. Default value is
1688 @code{kal}. See also the @var{list_voices} option.
1691 @subsection Examples
1695 Read from file @file{speech.txt}, and synthetize the text using the
1696 standard flite voice:
1698 flite=textfile=speech.txt
1702 Read the specified text selecting the @code{slt} voice:
1704 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1708 Input text to ffmpeg:
1710 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1714 Make @file{ffplay} speak the specified text, using @code{flite} and
1715 the @code{lavfi} device:
1717 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1721 For more information about libflite, check:
1722 @url{http://www.speech.cs.cmu.edu/flite/}
1726 Generate an audio signal made of a sine wave with amplitude 1/8.
1728 The audio signal is bit-exact.
1730 The filter accepts the following options:
1735 Set the carrier frequency. Default is 440 Hz.
1737 @item beep_factor, b
1738 Enable a periodic beep every second with frequency @var{beep_factor} times
1739 the carrier frequency. Default is 0, meaning the beep is disabled.
1741 @item sample_rate, s
1742 Specify the sample rate, default is 44100.
1745 Specify the duration of the generated audio stream.
1747 @item samples_per_frame
1748 Set the number of samples per output frame, default is 1024.
1751 @subsection Examples
1756 Generate a simple 440 Hz sine wave:
1762 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1766 sine=frequency=220:beep_factor=4:duration=5
1771 @c man end AUDIO SOURCES
1773 @chapter Audio Sinks
1774 @c man begin AUDIO SINKS
1776 Below is a description of the currently available audio sinks.
1778 @section abuffersink
1780 Buffer audio frames, and make them available to the end of filter chain.
1782 This sink is mainly intended for programmatic use, in particular
1783 through the interface defined in @file{libavfilter/buffersink.h}.
1785 It requires a pointer to an AVABufferSinkContext structure, which
1786 defines the incoming buffers' formats, to be passed as the opaque
1787 parameter to @code{avfilter_init_filter} for initialization.
1791 Null audio sink, do absolutely nothing with the input audio. It is
1792 mainly useful as a template and to be employed in analysis / debugging
1795 @section abuffersink
1796 This sink is intended for programmatic use. Frames that arrive on this sink can
1797 be retrieved by the calling program using the interface defined in
1798 @file{libavfilter/buffersink.h}.
1800 This filter accepts no parameters.
1802 @c man end AUDIO SINKS
1804 @chapter Video Filters
1805 @c man begin VIDEO FILTERS
1807 When you configure your FFmpeg build, you can disable any of the
1808 existing filters using @code{--disable-filters}.
1809 The configure output will show the video filters included in your
1812 Below is a description of the currently available video filters.
1814 @section alphaextract
1816 Extract the alpha component from the input as a grayscale video. This
1817 is especially useful with the @var{alphamerge} filter.
1821 Add or replace the alpha component of the primary input with the
1822 grayscale value of a second input. This is intended for use with
1823 @var{alphaextract} to allow the transmission or storage of frame
1824 sequences that have alpha in a format that doesn't support an alpha
1827 For example, to reconstruct full frames from a normal YUV-encoded video
1828 and a separate video created with @var{alphaextract}, you might use:
1830 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1833 Since this filter is designed for reconstruction, it operates on frame
1834 sequences without considering timestamps, and terminates when either
1835 input reaches end of stream. This will cause problems if your encoding
1836 pipeline drops frames. If you're trying to apply an image as an
1837 overlay to a video stream, consider the @var{overlay} filter instead.
1841 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1842 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1843 Substation Alpha) subtitles files.
1847 Compute the bounding box for the non-black pixels in the input frame
1850 This filter computes the bounding box containing all the pixels with a
1851 luminance value greater than the minimum allowed value.
1852 The parameters describing the bounding box are printed on the filter
1855 @section blackdetect
1857 Detect video intervals that are (almost) completely black. Can be
1858 useful to detect chapter transitions, commercials, or invalid
1859 recordings. Output lines contains the time for the start, end and
1860 duration of the detected black interval expressed in seconds.
1862 In order to display the output lines, you need to set the loglevel at
1863 least to the AV_LOG_INFO value.
1865 This filter accepts a list of options in the form of
1866 @var{key}=@var{value} pairs separated by ":". A description of the
1867 accepted options follows.
1870 @item black_min_duration, d
1871 Set the minimum detected black duration expressed in seconds. It must
1872 be a non-negative floating point number.
1874 Default value is 2.0.
1876 @item picture_black_ratio_th, pic_th
1877 Set the threshold for considering a picture "black".
1878 Express the minimum value for the ratio:
1880 @var{nb_black_pixels} / @var{nb_pixels}
1883 for which a picture is considered black.
1884 Default value is 0.98.
1886 @item pixel_black_th, pix_th
1887 Set the threshold for considering a pixel "black".
1889 The threshold expresses the maximum pixel luminance value for which a
1890 pixel is considered "black". The provided value is scaled according to
1891 the following equation:
1893 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1896 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1897 the input video format, the range is [0-255] for YUV full-range
1898 formats and [16-235] for YUV non full-range formats.
1900 Default value is 0.10.
1903 The following example sets the maximum pixel threshold to the minimum
1904 value, and detects only black intervals of 2 or more seconds:
1906 blackdetect=d=2:pix_th=0.00
1911 Detect frames that are (almost) completely black. Can be useful to
1912 detect chapter transitions or commercials. Output lines consist of
1913 the frame number of the detected frame, the percentage of blackness,
1914 the position in the file if known or -1 and the timestamp in seconds.
1916 In order to display the output lines, you need to set the loglevel at
1917 least to the AV_LOG_INFO value.
1919 The filter accepts parameters as a list of @var{key}=@var{value}
1920 pairs, separated by ":". If the key of the first options is omitted,
1921 the arguments are interpreted according to the syntax
1922 blackframe[=@var{amount}[:@var{threshold}]].
1924 The filter accepts the following options:
1929 The percentage of the pixels that have to be below the threshold, defaults to
1933 Threshold below which a pixel value is considered black, defaults to 32.
1939 Blend two video frames into each other.
1941 It takes two input streams and outputs one stream, the first input is the
1942 "top" layer and second input is "bottom" layer.
1943 Output terminates when shortest input terminates.
1945 A description of the accepted options follows.
1953 Set blend mode for specific pixel component or all pixel components in case
1954 of @var{all_mode}. Default value is @code{normal}.
1956 Available values for component modes are:
1989 Set blend opacity for specific pixel component or all pixel components in case
1990 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1997 Set blend expression for specific pixel component or all pixel components in case
1998 of @var{all_expr}. Note that related mode options will be ignored if those are set.
2000 The expressions can use the following variables:
2004 The sequential number of the filtered frame, starting from @code{0}.
2008 the coordinates of the current sample
2012 the width and height of currently filtered plane
2016 Width and height scale depending on the currently filtered plane. It is the
2017 ratio between the corresponding luma plane number of pixels and the current
2018 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2019 @code{0.5,0.5} for chroma planes.
2022 Time of the current frame, expressed in seconds.
2025 Value of pixel component at current location for first video frame (top layer).
2028 Value of pixel component at current location for second video frame (bottom layer).
2032 @subsection Examples
2036 Apply transition from bottom layer to top layer in first 10 seconds:
2038 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2042 Apply 1x1 checkerboard effect:
2044 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2050 Apply boxblur algorithm to the input video.
2052 The filter accepts parameters as a list of @var{key}=@var{value}
2053 pairs, separated by ":". If the key of the first options is omitted,
2054 the arguments are interpreted according to the syntax
2055 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2057 This filter accepts the following options:
2070 A description of the accepted options follows.
2073 @item luma_radius, lr
2074 @item chroma_radius, cr
2075 @item alpha_radius, ar
2076 Set an expression for the box radius in pixels used for blurring the
2077 corresponding input plane.
2079 The radius value must be a non-negative number, and must not be
2080 greater than the value of the expression @code{min(w,h)/2} for the
2081 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2084 Default value for @option{luma_radius} is "2". If not specified,
2085 @option{chroma_radius} and @option{alpha_radius} default to the
2086 corresponding value set for @option{luma_radius}.
2088 The expressions can contain the following constants:
2091 the input width and height in pixels
2094 the input chroma image width and height in pixels
2097 horizontal and vertical chroma subsample values. For example for the
2098 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2101 @item luma_power, lp
2102 @item chroma_power, cp
2103 @item alpha_power, ap
2104 Specify how many times the boxblur filter is applied to the
2105 corresponding plane.
2107 Default value for @option{luma_power} is 2. If not specified,
2108 @option{chroma_power} and @option{alpha_power} default to the
2109 corresponding value set for @option{luma_power}.
2111 A value of 0 will disable the effect.
2114 @subsection Examples
2118 Apply a boxblur filter with luma, chroma, and alpha radius
2121 boxblur=luma_radius=2:luma_power=1
2126 Set luma radius to 2, alpha and chroma radius to 0:
2128 boxblur=2:1:cr=0:ar=0
2132 Set luma and chroma radius to a fraction of the video dimension:
2134 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2138 @section colormatrix
2140 Convert color matrix.
2142 The filter accepts the following options:
2147 Specify the source and destination color matrix. Both values must be
2150 The accepted values are:
2166 For example to convert from BT.601 to SMPTE-240M, use the command:
2168 colormatrix=bt601:smpte240m
2173 Copy the input source unchanged to the output. Mainly useful for
2178 Crop the input video to given dimensions.
2180 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2181 separated by ':'. If the key of the first options is omitted, the
2182 arguments are interpreted according to the syntax
2183 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2185 A description of the accepted options follows:
2188 Width of the output video. It defaults to @code{iw}.
2189 This expression is evaluated only once during the filter
2193 Height of the output video. It defaults to @code{ih}.
2194 This expression is evaluated only once during the filter
2198 Horizontal position, in the input video, of the left edge of the output video.
2199 It defaults to @code{(in_w-out_w)/2}.
2200 This expression is evaluated per-frame.
2203 Vertical position, in the input video, of the top edge of the output video.
2204 It defaults to @code{(in_h-out_h)/2}.
2205 This expression is evaluated per-frame.
2208 If set to 1 will force the output display aspect ratio
2209 to be the same of the input, by changing the output sample aspect
2210 ratio. It defaults to 0.
2213 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2214 expressions containing the following constants:
2218 the computed values for @var{x} and @var{y}. They are evaluated for
2222 the input width and height
2225 same as @var{in_w} and @var{in_h}
2228 the output (cropped) width and height
2231 same as @var{out_w} and @var{out_h}
2234 same as @var{iw} / @var{ih}
2237 input sample aspect ratio
2240 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2243 horizontal and vertical chroma subsample values. For example for the
2244 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2247 the number of input frame, starting from 0
2250 timestamp expressed in seconds, NAN if the input timestamp is unknown
2254 The expression for @var{out_w} may depend on the value of @var{out_h},
2255 and the expression for @var{out_h} may depend on @var{out_w}, but they
2256 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2257 evaluated after @var{out_w} and @var{out_h}.
2259 The @var{x} and @var{y} parameters specify the expressions for the
2260 position of the top-left corner of the output (non-cropped) area. They
2261 are evaluated for each frame. If the evaluated value is not valid, it
2262 is approximated to the nearest valid value.
2264 The expression for @var{x} may depend on @var{y}, and the expression
2265 for @var{y} may depend on @var{x}.
2267 @subsection Examples
2271 Crop area with size 100x100 at position (12,34).
2276 Using named options, the example above becomes:
2278 crop=w=100:h=100:x=12:y=34
2282 Crop the central input area with size 100x100:
2288 Crop the central input area with size 2/3 of the input video:
2290 crop=2/3*in_w:2/3*in_h
2294 Crop the input video central square:
2301 Delimit the rectangle with the top-left corner placed at position
2302 100:100 and the right-bottom corner corresponding to the right-bottom
2303 corner of the input image:
2305 crop=in_w-100:in_h-100:100:100
2309 Crop 10 pixels from the left and right borders, and 20 pixels from
2310 the top and bottom borders
2312 crop=in_w-2*10:in_h-2*20
2316 Keep only the bottom right quarter of the input image:
2318 crop=in_w/2:in_h/2:in_w/2:in_h/2
2322 Crop height for getting Greek harmony:
2324 crop=in_w:1/PHI*in_w
2328 Appply trembling effect:
2330 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)
2334 Apply erratic camera effect depending on timestamp:
2336 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)"
2340 Set x depending on the value of y:
2342 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2348 Auto-detect crop size.
2350 Calculate necessary cropping parameters and prints the recommended
2351 parameters through the logging system. The detected dimensions
2352 correspond to the non-black area of the input video.
2354 The filter accepts parameters as a list of @var{key}=@var{value}
2355 pairs, separated by ":". If the key of the first options is omitted,
2356 the arguments are interpreted according to the syntax
2357 [@option{limit}[:@option{round}[:@option{reset}]]].
2359 A description of the accepted options follows.
2364 Set higher black value threshold, which can be optionally specified
2365 from nothing (0) to everything (255). An intensity value greater
2366 to the set value is considered non-black. Default value is 24.
2369 Set the value for which the width/height should be divisible by. The
2370 offset is automatically adjusted to center the video. Use 2 to get
2371 only even dimensions (needed for 4:2:2 video). 16 is best when
2372 encoding to most video codecs. Default value is 16.
2375 Set the counter that determines after how many frames cropdetect will
2376 reset the previously detected largest video area and start over to
2377 detect the current optimal crop area. Default value is 0.
2379 This can be useful when channel logos distort the video area. 0
2380 indicates never reset and return the largest area encountered during
2386 Apply color adjustments using curves.
2388 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2389 component (red, green and blue) has its values defined by @var{N} key points
2390 tied from each other using a smooth curve. The x-axis represents the pixel
2391 values from the input frame, and the y-axis the new pixel values to be set for
2394 By default, a component curve is defined by the two points @var{(0;0)} and
2395 @var{(1;1)}. This creates a straight line where each original pixel value is
2396 "adjusted" to its own value, which means no change to the image.
2398 The filter allows you to redefine these two points and add some more. A new
2399 curve (using a natural cubic spline interpolation) will be define to pass
2400 smoothly through all these new coordinates. The new defined points needs to be
2401 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2402 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2403 the vector spaces, the values will be clipped accordingly.
2405 If there is no key point defined in @code{x=0}, the filter will automatically
2406 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2407 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2409 The filter accepts the following options:
2413 Select one of the available color presets. This option can be used in addition
2414 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2415 options takes priority on the preset values.
2416 Available presets are:
2419 @item color_negative
2422 @item increase_contrast
2424 @item linear_contrast
2425 @item medium_contrast
2427 @item strong_contrast
2430 Default is @code{none}.
2432 Set the key points for the red component.
2434 Set the key points for the green component.
2436 Set the key points for the blue component.
2438 Set the key points for all components.
2439 Can be used in addition to the other key points component
2440 options. In this case, the unset component(s) will fallback on this
2441 @option{all} setting.
2444 To avoid some filtergraph syntax conflicts, each key points list need to be
2445 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2447 @subsection Examples
2451 Increase slightly the middle level of blue:
2453 curves=blue='0.5/0.58'
2459 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2461 Here we obtain the following coordinates for each components:
2464 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2466 @code{(0;0) (0.50;0.48) (1;1)}
2468 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2472 The previous example can also be achieved with the associated built-in preset:
2474 curves=preset=vintage
2486 Drop frames that do not differ greatly from the previous frame in
2487 order to reduce frame rate.
2489 The main use of this filter is for very-low-bitrate encoding
2490 (e.g. streaming over dialup modem), but it could in theory be used for
2491 fixing movies that were inverse-telecined incorrectly.
2493 A description of the accepted options follows.
2497 Set the maximum number of consecutive frames which can be dropped (if
2498 positive), or the minimum interval between dropped frames (if
2499 negative). If the value is 0, the frame is dropped unregarding the
2500 number of previous sequentially dropped frames.
2507 Set the dropping threshold values.
2509 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2510 represent actual pixel value differences, so a threshold of 64
2511 corresponds to 1 unit of difference for each pixel, or the same spread
2512 out differently over the block.
2514 A frame is a candidate for dropping if no 8x8 blocks differ by more
2515 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2516 meaning the whole image) differ by more than a threshold of @option{lo}.
2518 Default value for @option{hi} is 64*12, default value for @option{lo} is
2519 64*5, and default value for @option{frac} is 0.33.
2524 Suppress a TV station logo by a simple interpolation of the surrounding
2525 pixels. Just set a rectangle covering the logo and watch it disappear
2526 (and sometimes something even uglier appear - your mileage may vary).
2528 This filter accepts the following options:
2532 Specify the top left corner coordinates of the logo. They must be
2536 Specify the width and height of the logo to clear. They must be
2540 Specify the thickness of the fuzzy edge of the rectangle (added to
2541 @var{w} and @var{h}). The default value is 4.
2544 When set to 1, a green rectangle is drawn on the screen to simplify
2545 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2546 @var{band} is set to 4. The default value is 0.
2550 @subsection Examples
2554 Set a rectangle covering the area with top left corner coordinates 0,0
2555 and size 100x77, setting a band of size 10:
2557 delogo=x=0:y=0:w=100:h=77:band=10
2564 Attempt to fix small changes in horizontal and/or vertical shift. This
2565 filter helps remove camera shake from hand-holding a camera, bumping a
2566 tripod, moving on a vehicle, etc.
2568 The filter accepts the following options:
2576 Specify a rectangular area where to limit the search for motion
2578 If desired the search for motion vectors can be limited to a
2579 rectangular area of the frame defined by its top left corner, width
2580 and height. These parameters have the same meaning as the drawbox
2581 filter which can be used to visualise the position of the bounding
2584 This is useful when simultaneous movement of subjects within the frame
2585 might be confused for camera motion by the motion vector search.
2587 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2588 then the full frame is used. This allows later options to be set
2589 without specifying the bounding box for the motion vector search.
2591 Default - search the whole frame.
2595 Specify the maximum extent of movement in x and y directions in the
2596 range 0-64 pixels. Default 16.
2599 Specify how to generate pixels to fill blanks at the edge of the
2600 frame. Available values are:
2603 Fill zeroes at blank locations
2605 Original image at blank locations
2607 Extruded edge value at blank locations
2609 Mirrored edge at blank locations
2611 Default value is @samp{mirror}.
2614 Specify the blocksize to use for motion search. Range 4-128 pixels,
2618 Specify the contrast threshold for blocks. Only blocks with more than
2619 the specified contrast (difference between darkest and lightest
2620 pixels) will be considered. Range 1-255, default 125.
2623 Specify the search strategy. Available values are:
2626 Set exhaustive search
2628 Set less exhaustive search.
2630 Default value is @samp{exhaustive}.
2633 If set then a detailed log of the motion search is written to the
2637 If set to 1, specify using OpenCL capabilities, only available if
2638 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2644 Draw a colored box on the input image.
2646 This filter accepts the following options:
2650 Specify the top left corner coordinates of the box. Default to 0.
2654 Specify the width and height of the box, if 0 they are interpreted as
2655 the input width and height. Default to 0.
2658 Specify the color of the box to write, it can be the name of a color
2659 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2660 value @code{invert} is used, the box edge color is the same as the
2661 video with inverted luma.
2664 Set the thickness of the box edge. Default value is @code{4}.
2667 @subsection Examples
2671 Draw a black box around the edge of the input image:
2677 Draw a box with color red and an opacity of 50%:
2679 drawbox=10:20:200:60:red@@0.5
2682 The previous example can be specified as:
2684 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2688 Fill the box with pink color:
2690 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2697 Draw text string or text from specified file on top of video using the
2698 libfreetype library.
2700 To enable compilation of this filter you need to configure FFmpeg with
2701 @code{--enable-libfreetype}.
2705 The description of the accepted parameters follows.
2710 Used to draw a box around text using background color.
2711 Value should be either 1 (enable) or 0 (disable).
2712 The default value of @var{box} is 0.
2715 The color to be used for drawing box around text.
2716 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2717 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2718 The default value of @var{boxcolor} is "white".
2721 Set an expression which specifies if the text should be drawn. If the
2722 expression evaluates to 0, the text is not drawn. This is useful for
2723 specifying that the text should be drawn only when specific conditions
2726 Default value is "1".
2728 See below for the list of accepted constants and functions.
2731 Select how the @var{text} is expanded. Can be either @code{none},
2732 @code{strftime} (deprecated) or
2733 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2737 If true, check and fix text coords to avoid clipping.
2740 The color to be used for drawing fonts.
2741 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2742 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2743 The default value of @var{fontcolor} is "black".
2746 The font file to be used for drawing text. Path must be included.
2747 This parameter is mandatory.
2750 The font size to be used for drawing text.
2751 The default value of @var{fontsize} is 16.
2754 Flags to be used for loading the fonts.
2756 The flags map the corresponding flags supported by libfreetype, and are
2757 a combination of the following values:
2764 @item vertical_layout
2765 @item force_autohint
2768 @item ignore_global_advance_width
2770 @item ignore_transform
2777 Default value is "render".
2779 For more information consult the documentation for the FT_LOAD_*
2783 The color to be used for drawing a shadow behind the drawn text. It
2784 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2785 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2786 The default value of @var{shadowcolor} is "black".
2788 @item shadowx, shadowy
2789 The x and y offsets for the text shadow position with respect to the
2790 position of the text. They can be either positive or negative
2791 values. Default value for both is "0".
2794 The size in number of spaces to use for rendering the tab.
2798 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2799 format. It can be used with or without text parameter. @var{timecode_rate}
2800 option must be specified.
2802 @item timecode_rate, rate, r
2803 Set the timecode frame rate (timecode only).
2806 The text string to be drawn. The text must be a sequence of UTF-8
2808 This parameter is mandatory if no file is specified with the parameter
2812 A text file containing text to be drawn. The text must be a sequence
2813 of UTF-8 encoded characters.
2815 This parameter is mandatory if no text string is specified with the
2816 parameter @var{text}.
2818 If both @var{text} and @var{textfile} are specified, an error is thrown.
2821 If set to 1, the @var{textfile} will be reloaded before each frame.
2822 Be sure to update it atomically, or it may be read partially, or even fail.
2825 The expressions which specify the offsets where text will be drawn
2826 within the video frame. They are relative to the top/left border of the
2829 The default value of @var{x} and @var{y} is "0".
2831 See below for the list of accepted constants and functions.
2834 The parameters for @var{x} and @var{y} are expressions containing the
2835 following constants and functions:
2839 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2842 horizontal and vertical chroma subsample values. For example for the
2843 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2846 the height of each text line
2854 @item max_glyph_a, ascent
2855 the maximum distance from the baseline to the highest/upper grid
2856 coordinate used to place a glyph outline point, for all the rendered
2858 It is a positive value, due to the grid's orientation with the Y axis
2861 @item max_glyph_d, descent
2862 the maximum distance from the baseline to the lowest grid coordinate
2863 used to place a glyph outline point, for all the rendered glyphs.
2864 This is a negative value, due to the grid's orientation, with the Y axis
2868 maximum glyph height, that is the maximum height for all the glyphs
2869 contained in the rendered text, it is equivalent to @var{ascent} -
2873 maximum glyph width, that is the maximum width for all the glyphs
2874 contained in the rendered text
2877 the number of input frame, starting from 0
2879 @item rand(min, max)
2880 return a random number included between @var{min} and @var{max}
2883 input sample aspect ratio
2886 timestamp expressed in seconds, NAN if the input timestamp is unknown
2889 the height of the rendered text
2892 the width of the rendered text
2895 the x and y offset coordinates where the text is drawn.
2897 These parameters allow the @var{x} and @var{y} expressions to refer
2898 each other, so you can for example specify @code{y=x/dar}.
2901 If libavfilter was built with @code{--enable-fontconfig}, then
2902 @option{fontfile} can be a fontconfig pattern or omitted.
2904 @anchor{drawtext_expansion}
2905 @subsection Text expansion
2907 If @option{expansion} is set to @code{strftime},
2908 the filter recognizes strftime() sequences in the provided text and
2909 expands them accordingly. Check the documentation of strftime(). This
2910 feature is deprecated.
2912 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2914 If @option{expansion} is set to @code{normal} (which is the default),
2915 the following expansion mechanism is used.
2917 The backslash character '\', followed by any character, always expands to
2918 the second character.
2920 Sequence of the form @code{%@{...@}} are expanded. The text between the
2921 braces is a function name, possibly followed by arguments separated by ':'.
2922 If the arguments contain special characters or delimiters (':' or '@}'),
2923 they should be escaped.
2925 Note that they probably must also be escaped as the value for the
2926 @option{text} option in the filter argument string and as the filter
2927 argument in the filtergraph description, and possibly also for the shell,
2928 that makes up to four levels of escaping; using a text file avoids these
2931 The following functions are available:
2936 The expression evaluation result.
2938 It must take one argument specifying the expression to be evaluated,
2939 which accepts the same constants and functions as the @var{x} and
2940 @var{y} values. Note that not all constants should be used, for
2941 example the text size is not known when evaluating the expression, so
2942 the constants @var{text_w} and @var{text_h} will have an undefined
2946 The time at which the filter is running, expressed in UTC.
2947 It can accept an argument: a strftime() format string.
2950 The time at which the filter is running, expressed in the local time zone.
2951 It can accept an argument: a strftime() format string.
2954 The frame number, starting from 0.
2957 The timestamp of the current frame, in seconds, with microsecond accuracy.
2961 @subsection Examples
2965 Draw "Test Text" with font FreeSerif, using the default values for the
2966 optional parameters.
2969 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2973 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2974 and y=50 (counting from the top-left corner of the screen), text is
2975 yellow with a red box around it. Both the text and the box have an
2979 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2980 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2983 Note that the double quotes are not necessary if spaces are not used
2984 within the parameter list.
2987 Show the text at the center of the video frame:
2989 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2993 Show a text line sliding from right to left in the last row of the video
2994 frame. The file @file{LONG_LINE} is assumed to contain a single line
2997 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3001 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3003 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3007 Draw a single green letter "g", at the center of the input video.
3008 The glyph baseline is placed at half screen height.
3010 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3014 Show text for 1 second every 3 seconds:
3016 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3020 Use fontconfig to set the font. Note that the colons need to be escaped.
3022 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3026 Print the date of a real-time encoding (see strftime(3)):
3028 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3033 For more information about libfreetype, check:
3034 @url{http://www.freetype.org/}.
3036 For more information about fontconfig, check:
3037 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3041 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3043 The filter accepts the following options:
3047 Set low and high threshold values used by the Canny thresholding
3050 The high threshold selects the "strong" edge pixels, which are then
3051 connected through 8-connectivity with the "weak" edge pixels selected
3052 by the low threshold.
3054 @var{low} and @var{high} threshold values must be choosen in the range
3055 [0,1], and @var{low} should be lesser or equal to @var{high}.
3057 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3063 edgedetect=low=0.1:high=0.4
3068 Apply fade-in/out effect to input video.
3070 This filter accepts the following options:
3074 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3076 Default is @code{in}.
3078 @item start_frame, s
3079 Specify the number of the start frame for starting to apply the fade
3080 effect. Default is 0.
3083 The number of frames for which the fade effect has to last. At the end of the
3084 fade-in effect the output video will have the same intensity as the input video,
3085 at the end of the fade-out transition the output video will be completely black.
3089 If set to 1, fade only alpha channel, if one exists on the input.
3093 @subsection Examples
3097 Fade in first 30 frames of video:
3102 The command above is equivalent to:
3108 Fade out last 45 frames of a 200-frame video:
3111 fade=type=out:start_frame=155:nb_frames=45
3115 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3117 fade=in:0:25, fade=out:975:25
3121 Make first 5 frames black, then fade in from frame 5-24:
3127 Fade in alpha over first 25 frames of video:
3129 fade=in:0:25:alpha=1
3135 Extract a single field from an interlaced image using stride
3136 arithmetic to avoid wasting CPU time. The output frames are marked as
3139 The filter accepts the following options:
3143 Specify whether to extract the top (if the value is @code{0} or
3144 @code{top}) or the bottom field (if the value is @code{1} or
3150 Transform the field order of the input video.
3152 This filter accepts the following options:
3157 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3158 for bottom field first.
3161 Default value is @samp{tff}.
3163 Transformation is achieved by shifting the picture content up or down
3164 by one line, and filling the remaining line with appropriate picture content.
3165 This method is consistent with most broadcast field order converters.
3167 If the input video is not flagged as being interlaced, or it is already
3168 flagged as being of the required output field order then this filter does
3169 not alter the incoming video.
3171 This filter is very useful when converting to or from PAL DV material,
3172 which is bottom field first.
3176 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3181 Buffer input images and send them when they are requested.
3183 This filter is mainly useful when auto-inserted by the libavfilter
3186 The filter does not take parameters.
3191 Convert the input video to one of the specified pixel formats.
3192 Libavfilter will try to pick one that is supported for the input to
3195 This filter accepts the following parameters:
3199 A '|'-separated list of pixel format names, for example
3200 "pix_fmts=yuv420p|monow|rgb24".
3204 @subsection Examples
3208 Convert the input video to the format @var{yuv420p}
3210 format=pix_fmts=yuv420p
3213 Convert the input video to any of the formats in the list
3215 format=pix_fmts=yuv420p|yuv444p|yuv410p
3221 Convert the video to specified constant frame rate by duplicating or dropping
3222 frames as necessary.
3224 This filter accepts the following named parameters:
3228 Desired output frame rate. The default is @code{25}.
3233 Possible values are:
3236 zero round towards 0
3240 round towards -infinity
3242 round towards +infinity
3246 The default is @code{near}.
3250 Alternatively, the options can be specified as a flat string:
3251 @var{fps}[:@var{round}].
3253 See also the @ref{setpts} filter.
3257 Select one frame every N-th frame.
3259 This filter accepts the following option:
3262 Select frame after every @code{step} frames.
3263 Allowed values are positive integers higher than 0. Default value is @code{1}.
3269 Apply a frei0r effect to the input video.
3271 To enable compilation of this filter you need to install the frei0r
3272 header and configure FFmpeg with @code{--enable-frei0r}.
3274 This filter accepts the following options:
3279 The name to the frei0r effect to load. If the environment variable
3280 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3281 directories specified by the colon separated list in @env{FREIOR_PATH},
3282 otherwise in the standard frei0r paths, which are in this order:
3283 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3284 @file{/usr/lib/frei0r-1/}.
3287 A '|'-separated list of parameters to pass to the frei0r effect.
3291 A frei0r effect parameter can be a boolean (whose values are specified
3292 with "y" and "n"), a double, a color (specified by the syntax
3293 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3294 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3295 description), a position (specified by the syntax @var{X}/@var{Y},
3296 @var{X} and @var{Y} being float numbers) and a string.
3298 The number and kind of parameters depend on the loaded effect. If an
3299 effect parameter is not specified the default value is set.
3301 @subsection Examples
3305 Apply the distort0r effect, set the first two double parameters:
3307 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3311 Apply the colordistance effect, take a color as first parameter:
3313 frei0r=colordistance:0.2/0.3/0.4
3314 frei0r=colordistance:violet
3315 frei0r=colordistance:0x112233
3319 Apply the perspective effect, specify the top left and top right image
3322 frei0r=perspective:0.2/0.2|0.8/0.2
3326 For more information see:
3327 @url{http://frei0r.dyne.org}
3331 The filter accepts the following options:
3335 the luminance expression
3337 the chrominance blue expression
3339 the chrominance red expression
3341 the alpha expression
3344 If one of the chrominance expression is not defined, it falls back on the other
3345 one. If no alpha expression is specified it will evaluate to opaque value.
3346 If none of chrominance expressions are
3347 specified, they will evaluate the luminance expression.
3349 The expressions can use the following variables and functions:
3353 The sequential number of the filtered frame, starting from @code{0}.
3357 The coordinates of the current sample.
3361 The width and height of the image.
3365 Width and height scale depending on the currently filtered plane. It is the
3366 ratio between the corresponding luma plane number of pixels and the current
3367 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3368 @code{0.5,0.5} for chroma planes.
3371 Time of the current frame, expressed in seconds.
3374 Return the value of the pixel at location (@var{x},@var{y}) of the current
3378 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3382 Return the value of the pixel at location (@var{x},@var{y}) of the
3383 blue-difference chroma plane. Returns 0 if there is no such plane.
3386 Return the value of the pixel at location (@var{x},@var{y}) of the
3387 red-difference chroma plane. Returns 0 if there is no such plane.
3390 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3391 plane. Returns 0 if there is no such plane.
3394 For functions, if @var{x} and @var{y} are outside the area, the value will be
3395 automatically clipped to the closer edge.
3397 @subsection Examples
3401 Flip the image horizontally:
3407 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3408 wavelength of 100 pixels:
3410 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3414 Generate a fancy enigmatic moving light:
3416 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
3422 Fix the banding artifacts that are sometimes introduced into nearly flat
3423 regions by truncation to 8bit color depth.
3424 Interpolate the gradients that should go where the bands are, and
3427 This filter is designed for playback only. Do not use it prior to
3428 lossy compression, because compression tends to lose the dither and
3429 bring back the bands.
3431 This filter accepts the following options:
3436 The maximum amount by which the filter will change any one pixel. Also the
3437 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3438 64, default value is 1.2, out-of-range values will be clipped to the valid
3442 The neighborhood to fit the gradient to. A larger radius makes for smoother
3443 gradients, but also prevents the filter from modifying the pixels near detailed
3444 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3445 will be clipped to the valid range.
3449 Alternatively, the options can be specified as a flat string:
3450 @var{strength}[:@var{radius}]
3452 @subsection Examples
3456 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3462 Specify radius, omitting the strength (which will fall-back to the default
3472 Flip the input video horizontally.
3474 For example to horizontally flip the input video with @command{ffmpeg}:
3476 ffmpeg -i in.avi -vf "hflip" out.avi
3480 This filter applies a global color histogram equalization on a
3483 It can be used to correct video that has a compressed range of pixel
3484 intensities. The filter redistributes the pixel intensities to
3485 equalize their distribution across the intensity range. It may be
3486 viewed as an "automatically adjusting contrast filter". This filter is
3487 useful only for correcting degraded or poorly captured source
3490 The filter accepts the following options:
3494 Determine the amount of equalization to be applied. As the strength
3495 is reduced, the distribution of pixel intensities more-and-more
3496 approaches that of the input frame. The value must be a float number
3497 in the range [0,1] and defaults to 0.200.
3500 Set the maximum intensity that can generated and scale the output
3501 values appropriately. The strength should be set as desired and then
3502 the intensity can be limited if needed to avoid washing-out. The value
3503 must be a float number in the range [0,1] and defaults to 0.210.
3506 Set the antibanding level. If enabled the filter will randomly vary
3507 the luminance of output pixels by a small amount to avoid banding of
3508 the histogram. Possible values are @code{none}, @code{weak} or
3509 @code{strong}. It defaults to @code{none}.
3514 Compute and draw a color distribution histogram for the input video.
3516 The computed histogram is a representation of distribution of color components
3519 The filter accepts the following options:
3525 It accepts the following values:
3528 standard histogram that display color components distribution in an image.
3529 Displays color graph for each color component. Shows distribution
3530 of the Y, U, V, A or G, B, R components, depending on input format,
3531 in current frame. Bellow each graph is color component scale meter.
3534 chroma values in vectorscope, if brighter more such chroma values are
3535 distributed in an image.
3536 Displays chroma values (U/V color placement) in two dimensional graph
3537 (which is called a vectorscope). It can be used to read of the hue and
3538 saturation of the current frame. At a same time it is a histogram.
3539 The whiter a pixel in the vectorscope, the more pixels of the input frame
3540 correspond to that pixel (that is the more pixels have this chroma value).
3541 The V component is displayed on the horizontal (X) axis, with the leftmost
3542 side being V = 0 and the rightmost side being V = 255.
3543 The U component is displayed on the vertical (Y) axis, with the top
3544 representing U = 0 and the bottom representing U = 255.
3546 The position of a white pixel in the graph corresponds to the chroma value
3547 of a pixel of the input clip. So the graph can be used to read of the
3548 hue (color flavor) and the saturation (the dominance of the hue in the color).
3549 As the hue of a color changes, it moves around the square. At the center of
3550 the square, the saturation is zero, which means that the corresponding pixel
3551 has no color. If you increase the amount of a specific color, while leaving
3552 the other colors unchanged, the saturation increases, and you move towards
3553 the edge of the square.
3556 chroma values in vectorscope, similar as @code{color} but actual chroma values
3560 per row/column color component graph. In row mode graph in the left side represents
3561 color component value 0 and right side represents value = 255. In column mode top
3562 side represents color component value = 0 and bottom side represents value = 255.
3564 Default value is @code{levels}.
3567 Set height of level in @code{levels}. Default value is @code{200}.
3568 Allowed range is [50, 2048].
3571 Set height of color scale in @code{levels}. Default value is @code{12}.
3572 Allowed range is [0, 40].
3575 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3576 of same luminance values across input rows/columns are distributed.
3577 Default value is @code{10}. Allowed range is [1, 255].
3580 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3581 Default is @code{row}.
3584 Set display mode for @code{waveform} and @code{levels}.
3585 It accepts the following values:
3588 Display separate graph for the color components side by side in
3589 @code{row} waveform mode or one below other in @code{column} waveform mode
3590 for @code{waveform} histogram mode. For @code{levels} histogram mode
3591 per color component graphs are placed one bellow other.
3593 This display mode in @code{waveform} histogram mode makes it easy to spot
3594 color casts in the highlights and shadows of an image, by comparing the
3595 contours of the top and the bottom of each waveform.
3596 Since whites, grays, and blacks are characterized by
3597 exactly equal amounts of red, green, and blue, neutral areas of the
3598 picture should display three waveforms of roughly equal width/height.
3599 If not, the correction is easy to make by making adjustments to level the
3603 Presents information that's identical to that in the @code{parade}, except
3604 that the graphs representing color components are superimposed directly
3607 This display mode in @code{waveform} histogram mode can make it easier to spot
3608 the relative differences or similarities in overlapping areas of the color
3609 components that are supposed to be identical, such as neutral whites, grays,
3612 Default is @code{parade}.
3615 @subsection Examples
3620 Calculate and draw histogram:
3622 ffplay -i input -vf histogram
3629 High precision/quality 3d denoise filter. This filter aims to reduce
3630 image noise producing smooth images and making still images really
3631 still. It should enhance compressibility.
3633 It accepts the following optional parameters:
3637 a non-negative float number which specifies spatial luma strength,
3640 @item chroma_spatial
3641 a non-negative float number which specifies spatial chroma strength,
3642 defaults to 3.0*@var{luma_spatial}/4.0
3645 a float number which specifies luma temporal strength, defaults to
3646 6.0*@var{luma_spatial}/4.0
3649 a float number which specifies chroma temporal strength, defaults to
3650 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3655 Modify the hue and/or the saturation of the input.
3657 This filter accepts the following optional named options:
3661 Specify the hue angle as a number of degrees. It accepts a float
3662 number or an expression, and defaults to 0.0.
3665 Specify the hue angle as a number of radians. It accepts a float
3666 number or an expression, and defaults to 0.0.
3669 Specify the saturation in the [-10,10] range. It accepts a float number and
3673 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3674 following constants:
3678 frame count of the input frame starting from 0
3681 presentation timestamp of the input frame expressed in time base units
3684 frame rate of the input video, NAN if the input frame rate is unknown
3687 timestamp expressed in seconds, NAN if the input timestamp is unknown
3690 time base of the input video
3693 The options can also be set using the syntax: @var{hue}:@var{saturation}
3695 In this case @var{hue} is expressed in degrees.
3697 @subsection Examples
3701 Set the hue to 90 degrees and the saturation to 1.0:
3707 Same command but expressing the hue in radians:
3713 Same command without named options, hue must be expressed in degrees:
3719 Note that "h:s" syntax does not support expressions for the values of
3720 h and s, so the following example will issue an error:
3726 Rotate hue and make the saturation swing between 0
3727 and 2 over a period of 1 second:
3729 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3733 Apply a 3 seconds saturation fade-in effect starting at 0:
3738 The general fade-in expression can be written as:
3740 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3744 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3746 hue="s=max(0\, min(1\, (8-t)/3))"
3749 The general fade-out expression can be written as:
3751 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3756 @subsection Commands
3758 This filter supports the following command:
3761 Modify the hue and/or the saturation of the input video.
3762 The command accepts the same named options and syntax than when calling the
3763 filter from the command-line.
3765 If a parameter is omitted, it is kept at its current value.
3770 Detect video interlacing type.
3772 This filter tries to detect if the input is interlaced or progressive,
3773 top or bottom field first.
3775 The filter accepts the following options:
3779 Set interlacing threshold.
3781 Set progressive threshold.
3786 Deinterleave or interleave fields.
3788 This filter allows to process interlaced images fields without
3789 deinterlacing them. Deinterleaving splits the input frame into 2
3790 fields (so called half pictures). Odd lines are moved to the top
3791 half of the output image, even lines to the bottom half.
3792 You can process (filter) them independently and then re-interleave them.
3794 The filter accepts the following options:
3798 @item chroma_mode, s
3800 Available values for @var{luma_mode}, @var{chroma_mode} and
3801 @var{alpha_mode} are:
3807 @item deinterleave, d
3808 Deinterleave fields, placing one above the other.
3811 Interleave fields. Reverse the effect of deinterleaving.
3813 Default value is @code{none}.
3816 @item chroma_swap, cs
3817 @item alpha_swap, as
3818 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3823 Deinterlace input video by applying Donald Graft's adaptive kernel
3824 deinterling. Work on interlaced parts of a video to produce
3827 The description of the accepted parameters follows.
3831 Set the threshold which affects the filter's tolerance when
3832 determining if a pixel line must be processed. It must be an integer
3833 in the range [0,255] and defaults to 10. A value of 0 will result in
3834 applying the process on every pixels.
3837 Paint pixels exceeding the threshold value to white if set to 1.
3841 Set the fields order. Swap fields if set to 1, leave fields alone if
3845 Enable additional sharpening if set to 1. Default is 0.
3848 Enable twoway sharpening if set to 1. Default is 0.
3851 @subsection Examples
3855 Apply default values:
3857 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3861 Enable additional sharpening:
3867 Paint processed pixels in white:
3873 @section lut, lutrgb, lutyuv
3875 Compute a look-up table for binding each pixel component input value
3876 to an output value, and apply it to input video.
3878 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3879 to an RGB input video.
3881 These filters accept the following options:
3884 set first pixel component expression
3886 set second pixel component expression
3888 set third pixel component expression
3890 set fourth pixel component expression, corresponds to the alpha component
3893 set red component expression
3895 set green component expression
3897 set blue component expression
3899 alpha component expression
3902 set Y/luminance component expression
3904 set U/Cb component expression
3906 set V/Cr component expression
3909 Each of them specifies the expression to use for computing the lookup table for
3910 the corresponding pixel component values.
3912 The exact component associated to each of the @var{c*} options depends on the
3915 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3916 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3918 The expressions can contain the following constants and functions:
3922 the input width and height
3925 input value for the pixel component
3928 the input value clipped in the @var{minval}-@var{maxval} range
3931 maximum value for the pixel component
3934 minimum value for the pixel component
3937 the negated value for the pixel component value clipped in the
3938 @var{minval}-@var{maxval} range , it corresponds to the expression
3939 "maxval-clipval+minval"
3942 the computed value in @var{val} clipped in the
3943 @var{minval}-@var{maxval} range
3945 @item gammaval(gamma)
3946 the computed gamma correction value of the pixel component value
3947 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3949 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3953 All expressions default to "val".
3955 @subsection Examples
3961 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3962 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3965 The above is the same as:
3967 lutrgb="r=negval:g=negval:b=negval"
3968 lutyuv="y=negval:u=negval:v=negval"
3978 Remove chroma components, turns the video into a graytone image:
3980 lutyuv="u=128:v=128"
3984 Apply a luma burning effect:
3990 Remove green and blue components:
3996 Set a constant alpha channel value on input:
3998 format=rgba,lutrgb=a="maxval-minval/2"
4002 Correct luminance gamma by a 0.5 factor:
4004 lutyuv=y=gammaval(0.5)
4008 Discard least significant bits of luma:
4010 lutyuv=y='bitand(val, 128+64+32)'
4016 Apply an MPlayer filter to the input video.
4018 This filter provides a wrapper around most of the filters of
4021 This wrapper is considered experimental. Some of the wrapped filters
4022 may not work properly and we may drop support for them, as they will
4023 be implemented natively into FFmpeg. Thus you should avoid
4024 depending on them when writing portable scripts.
4026 The filters accepts the parameters:
4027 @var{filter_name}[:=]@var{filter_params}
4029 @var{filter_name} is the name of a supported MPlayer filter,
4030 @var{filter_params} is a string containing the parameters accepted by
4033 The list of the currently supported filters follows:
4060 The parameter syntax and behavior for the listed filters are the same
4061 of the corresponding MPlayer filters. For detailed instructions check
4062 the "VIDEO FILTERS" section in the MPlayer manual.
4064 @subsection Examples
4068 Adjust gamma, brightness, contrast:
4074 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4080 This filter accepts an integer in input, if non-zero it negates the
4081 alpha component (if available). The default value in input is 0.
4085 Force libavfilter not to use any of the specified pixel formats for the
4086 input to the next filter.
4088 This filter accepts the following parameters:
4092 A '|'-separated list of pixel format names, for example
4093 "pix_fmts=yuv420p|monow|rgb24".
4097 @subsection Examples
4101 Force libavfilter to use a format different from @var{yuv420p} for the
4102 input to the vflip filter:
4104 noformat=pix_fmts=yuv420p,vflip
4108 Convert the input video to any of the formats not contained in the list:
4110 noformat=yuv420p|yuv444p|yuv410p
4116 Add noise on video input frame.
4118 The filter accepts the following options:
4126 Set noise seed for specific pixel component or all pixel components in case
4127 of @var{all_seed}. Default value is @code{123457}.
4129 @item all_strength, alls
4130 @item c0_strength, c0s
4131 @item c1_strength, c1s
4132 @item c2_strength, c2s
4133 @item c3_strength, c3s
4134 Set noise strength for specific pixel component or all pixel components in case
4135 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4137 @item all_flags, allf
4142 Set pixel component flags or set flags for all components if @var{all_flags}.
4143 Available values for component flags are:
4146 averaged temporal noise (smoother)
4148 mix random noise with a (semi)regular pattern
4150 higher quality (slightly better looking, slightly slower)
4152 temporal noise (noise pattern changes between frames)
4154 uniform noise (gaussian otherwise)
4158 @subsection Examples
4160 Add temporal and uniform noise to input video:
4162 noise=alls=20:allf=t+u
4167 Pass the video source unchanged to the output.
4171 Apply video transform using libopencv.
4173 To enable this filter install libopencv library and headers and
4174 configure FFmpeg with @code{--enable-libopencv}.
4176 This filter accepts the following parameters:
4181 The name of the libopencv filter to apply.
4184 The parameters to pass to the libopencv filter. If not specified the default
4189 Refer to the official libopencv documentation for more precise
4191 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4193 Follows the list of supported libopencv filters.
4198 Dilate an image by using a specific structuring element.
4199 This filter corresponds to the libopencv function @code{cvDilate}.
4201 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4203 @var{struct_el} represents a structuring element, and has the syntax:
4204 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4206 @var{cols} and @var{rows} represent the number of columns and rows of
4207 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4208 point, and @var{shape} the shape for the structuring element, and
4209 can be one of the values "rect", "cross", "ellipse", "custom".
4211 If the value for @var{shape} is "custom", it must be followed by a
4212 string of the form "=@var{filename}". The file with name
4213 @var{filename} is assumed to represent a binary image, with each
4214 printable character corresponding to a bright pixel. When a custom
4215 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4216 or columns and rows of the read file are assumed instead.
4218 The default value for @var{struct_el} is "3x3+0x0/rect".
4220 @var{nb_iterations} specifies the number of times the transform is
4221 applied to the image, and defaults to 1.
4223 Follow some example:
4225 # use the default values
4228 # dilate using a structuring element with a 5x5 cross, iterate two times
4229 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4231 # read the shape from the file diamond.shape, iterate two times
4232 # the file diamond.shape may contain a pattern of characters like this:
4238 # the specified cols and rows are ignored (but not the anchor point coordinates)
4239 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4244 Erode an image by using a specific structuring element.
4245 This filter corresponds to the libopencv function @code{cvErode}.
4247 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4248 with the same syntax and semantics as the @ref{dilate} filter.
4252 Smooth the input video.
4254 The filter takes the following parameters:
4255 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4257 @var{type} is the type of smooth filter to apply, and can be one of
4258 the following values: "blur", "blur_no_scale", "median", "gaussian",
4259 "bilateral". The default value is "gaussian".
4261 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4262 parameters whose meanings depend on smooth type. @var{param1} and
4263 @var{param2} accept integer positive values or 0, @var{param3} and
4264 @var{param4} accept float values.
4266 The default value for @var{param1} is 3, the default value for the
4267 other parameters is 0.
4269 These parameters correspond to the parameters assigned to the
4270 libopencv function @code{cvSmooth}.
4275 Overlay one video on top of another.
4277 It takes two inputs and one output, the first input is the "main"
4278 video on which the second input is overlayed.
4280 This filter accepts the following parameters:
4282 A description of the accepted options follows.
4287 Set the expression for the x and y coordinates of the overlayed video
4288 on the main video. Default value is "0" for both expressions. In case
4289 the expression is invalid, it is set to a huge value (meaning that the
4290 overlay will not be displayed within the output visible area).
4293 Set the expression which enables the overlay. If the evaluation is
4294 different from 0, the overlay is displayed on top of the input
4295 frame. By default it is "1".
4298 Set when the expressions for @option{x}, @option{y}, and
4299 @option{enable} are evaluated.
4301 It accepts the following values:
4304 only evaluate expressions once during the filter initialization or
4305 when a command is processed
4308 evaluate expressions for each incoming frame
4311 Default value is @samp{frame}.
4314 If set to 1, force the output to terminate when the shortest input
4315 terminates. Default value is 0.
4318 Set the format for the output video.
4320 It accepts the following values:
4332 Default value is @samp{yuv420}.
4334 @item rgb @emph{(deprecated)}
4335 If set to 1, force the filter to accept inputs in the RGB
4336 color space. Default value is 0. This option is deprecated, use
4337 @option{format} instead.
4340 The @option{x}, @option{y}, and @option{enable} expressions can
4341 contain the following parameters.
4346 main input width and height
4350 overlay input width and height
4354 the computed values for @var{x} and @var{y}. They are evaluated for
4359 horizontal and vertical chroma subsample values of the output
4360 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4364 the number of input frame, starting from 0
4367 the position in the file of the input frame, NAN if unknown
4370 timestamp expressed in seconds, NAN if the input timestamp is unknown
4373 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4374 when evaluation is done @emph{per frame}, and will evaluate to NAN
4375 when @option{eval} is set to @samp{init}.
4377 Be aware that frames are taken from each input video in timestamp
4378 order, hence, if their initial timestamps differ, it is a a good idea
4379 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4380 have them begin in the same zero timestamp, as it does the example for
4381 the @var{movie} filter.
4383 You can chain together more overlays but you should test the
4384 efficiency of such approach.
4386 @subsection Commands
4388 This filter supports the following command:
4391 Set the @option{x} option expression.
4394 Set the @option{y} option expression.
4397 Set the @option{enable} option expression.
4400 @subsection Examples
4404 Draw the overlay at 10 pixels from the bottom right corner of the main
4407 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4410 Using named options the example above becomes:
4412 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4416 Insert a transparent PNG logo in the bottom left corner of the input,
4417 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4419 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4423 Insert 2 different transparent PNG logos (second logo on bottom
4424 right corner) using the @command{ffmpeg} tool:
4426 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
4430 Add a transparent color layer on top of the main video, @code{WxH}
4431 must specify the size of the main input to the overlay filter:
4433 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4437 Play an original video and a filtered version (here with the deshake
4438 filter) side by side using the @command{ffplay} tool:
4440 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4443 The above command is the same as:
4445 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4449 Make a sliding overlay appearing from the left to the right top part of the
4450 screen starting since time 2:
4452 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4456 Compose output by putting two input videos side to side:
4458 ffmpeg -i left.avi -i right.avi -filter_complex "
4459 nullsrc=size=200x100 [background];
4460 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4461 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4462 [background][left] overlay=shortest=1 [background+left];
4463 [background+left][right] overlay=shortest=1:x=100 [left+right]
4468 Chain several overlays in cascade:
4470 nullsrc=s=200x200 [bg];
4471 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4472 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4473 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4474 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4475 [in3] null, [mid2] overlay=100:100 [out0]
4482 Add paddings to the input image, and place the original input at the
4483 given coordinates @var{x}, @var{y}.
4485 This filter accepts the following parameters:
4490 Specify an expression for the size of the output image with the
4491 paddings added. If the value for @var{width} or @var{height} is 0, the
4492 corresponding input size is used for the output.
4494 The @var{width} expression can reference the value set by the
4495 @var{height} expression, and vice versa.
4497 The default value of @var{width} and @var{height} is 0.
4501 Specify an expression for the offsets where to place the input image
4502 in the padded area with respect to the top/left border of the output
4505 The @var{x} expression can reference the value set by the @var{y}
4506 expression, and vice versa.
4508 The default value of @var{x} and @var{y} is 0.
4511 Specify the color of the padded area, it can be the name of a color
4512 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4514 The default value of @var{color} is "black".
4517 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4518 options are expressions containing the following constants:
4522 the input video width and height
4525 same as @var{in_w} and @var{in_h}
4528 the output width and height, that is the size of the padded area as
4529 specified by the @var{width} and @var{height} expressions
4532 same as @var{out_w} and @var{out_h}
4535 x and y offsets as specified by the @var{x} and @var{y}
4536 expressions, or NAN if not yet specified
4539 same as @var{iw} / @var{ih}
4542 input sample aspect ratio
4545 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4548 horizontal and vertical chroma subsample values. For example for the
4549 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4552 @subsection Examples
4556 Add paddings with color "violet" to the input video. Output video
4557 size is 640x480, the top-left corner of the input video is placed at
4560 pad=640:480:0:40:violet
4563 The example above is equivalent to the following command:
4565 pad=width=640:height=480:x=0:y=40:color=violet
4569 Pad the input to get an output with dimensions increased by 3/2,
4570 and put the input video at the center of the padded area:
4572 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4576 Pad the input to get a squared output with size equal to the maximum
4577 value between the input width and height, and put the input video at
4578 the center of the padded area:
4580 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4584 Pad the input to get a final w/h ratio of 16:9:
4586 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4590 In case of anamorphic video, in order to set the output display aspect
4591 correctly, it is necessary to use @var{sar} in the expression,
4592 according to the relation:
4594 (ih * X / ih) * sar = output_dar
4595 X = output_dar / sar
4598 Thus the previous example needs to be modified to:
4600 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4604 Double output size and put the input video in the bottom-right
4605 corner of the output padded area:
4607 pad="2*iw:2*ih:ow-iw:oh-ih"
4611 @section pixdesctest
4613 Pixel format descriptor test filter, mainly useful for internal
4614 testing. The output video should be equal to the input video.
4618 format=monow, pixdesctest
4621 can be used to test the monowhite pixel format descriptor definition.
4625 Enable the specified chain of postprocessing subfilters using libpostproc. This
4626 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4627 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4628 Each subfilter and some options have a short and a long name that can be used
4629 interchangeably, i.e. dr/dering are the same.
4631 The filters accept the following options:
4635 Set postprocessing subfilters string.
4638 All subfilters share common options to determine their scope:
4642 Honor the quality commands for this subfilter.
4645 Do chrominance filtering, too (default).
4648 Do luminance filtering only (no chrominance).
4651 Do chrominance filtering only (no luminance).
4654 These options can be appended after the subfilter name, separated by a '|'.
4656 Available subfilters are:
4659 @item hb/hdeblock[|difference[|flatness]]
4660 Horizontal deblocking filter
4663 Difference factor where higher values mean more deblocking (default: @code{32}).
4665 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4668 @item vb/vdeblock[|difference[|flatness]]
4669 Vertical deblocking filter
4672 Difference factor where higher values mean more deblocking (default: @code{32}).
4674 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4677 @item ha/hadeblock[|difference[|flatness]]
4678 Accurate horizontal deblocking filter
4681 Difference factor where higher values mean more deblocking (default: @code{32}).
4683 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4686 @item va/vadeblock[|difference[|flatness]]
4687 Accurate vertical deblocking filter
4690 Difference factor where higher values mean more deblocking (default: @code{32}).
4692 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4696 The horizontal and vertical deblocking filters share the difference and
4697 flatness values so you cannot set different horizontal and vertical
4702 Experimental horizontal deblocking filter
4705 Experimental vertical deblocking filter
4710 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4713 larger -> stronger filtering
4715 larger -> stronger filtering
4717 larger -> stronger filtering
4720 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4723 Stretch luminance to @code{0-255}.
4726 @item lb/linblenddeint
4727 Linear blend deinterlacing filter that deinterlaces the given block by
4728 filtering all lines with a @code{(1 2 1)} filter.
4730 @item li/linipoldeint
4731 Linear interpolating deinterlacing filter that deinterlaces the given block by
4732 linearly interpolating every second line.
4734 @item ci/cubicipoldeint
4735 Cubic interpolating deinterlacing filter deinterlaces the given block by
4736 cubically interpolating every second line.
4738 @item md/mediandeint
4739 Median deinterlacing filter that deinterlaces the given block by applying a
4740 median filter to every second line.
4742 @item fd/ffmpegdeint
4743 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4744 second line with a @code{(-1 4 2 4 -1)} filter.
4747 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4748 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4750 @item fq/forceQuant[|quantizer]
4751 Overrides the quantizer table from the input with the constant quantizer you
4759 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4762 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4765 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4768 @subsection Examples
4772 Apply horizontal and vertical deblocking, deringing and automatic
4773 brightness/contrast:
4779 Apply default filters without brightness/contrast correction:
4785 Apply default filters and temporal denoiser:
4787 pp=default/tmpnoise|1|2|3
4791 Apply deblocking on luminance only, and switch vertical deblocking on or off
4792 automatically depending on available CPU time:
4800 Suppress a TV station logo, using an image file to determine which
4801 pixels comprise the logo. It works by filling in the pixels that
4802 comprise the logo with neighboring pixels.
4804 This filter requires one argument which specifies the filter bitmap
4805 file, which can be any image format supported by libavformat. The
4806 width and height of the image file must match those of the video
4807 stream being processed.
4809 Pixels in the provided bitmap image with a value of zero are not
4810 considered part of the logo, non-zero pixels are considered part of
4811 the logo. If you use white (255) for the logo and black (0) for the
4812 rest, you will be safe. For making the filter bitmap, it is
4813 recommended to take a screen capture of a black frame with the logo
4814 visible, and then using a threshold filter followed by the erode
4815 filter once or twice.
4817 If needed, little splotches can be fixed manually. Remember that if
4818 logo pixels are not covered, the filter quality will be much
4819 reduced. Marking too many pixels as part of the logo does not hurt as
4820 much, but it will increase the amount of blurring needed to cover over
4821 the image and will destroy more information than necessary, and extra
4822 pixels will slow things down on a large logo.
4826 Scale (resize) the input video, using the libswscale library.
4828 The scale filter forces the output display aspect ratio to be the same
4829 of the input, by changing the output sample aspect ratio.
4831 This filter accepts a list of named options in the form of
4832 @var{key}=@var{value} pairs separated by ":". If the key for the first
4833 two options is not specified, the assumed keys for the first two
4834 values are @code{w} and @code{h}. If the first option has no key and
4835 can be interpreted like a video size specification, it will be used
4836 to set the video size.
4838 A description of the accepted options follows.
4843 default value is @code{iw}. See below
4844 for the list of accepted constants.
4847 Output video height.
4848 default value is @code{ih}.
4849 See below for the list of accepted constants.
4852 Set the interlacing. It accepts the following values:
4856 force interlaced aware scaling
4859 do not apply interlaced scaling
4862 select interlaced aware scaling depending on whether the source frames
4863 are flagged as interlaced or not
4866 Default value is @code{0}.
4869 Set libswscale scaling flags. If not explictly specified the filter
4870 applies a bilinear scaling algorithm.
4873 Set the video size, the value must be a valid abbreviation or in the
4874 form @var{width}x@var{height}.
4877 The values of the @var{w} and @var{h} options are expressions
4878 containing the following constants:
4882 the input width and height
4885 same as @var{in_w} and @var{in_h}
4888 the output (cropped) width and height
4891 same as @var{out_w} and @var{out_h}
4894 same as @var{iw} / @var{ih}
4897 input sample aspect ratio
4900 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4903 horizontal and vertical chroma subsample values. For example for the
4904 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4907 If the input image format is different from the format requested by
4908 the next filter, the scale filter will convert the input to the
4911 If the value for @var{w} or @var{h} is 0, the respective input
4912 size is used for the output.
4914 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4915 respective output size, a value that maintains the aspect ratio of the input
4918 @subsection Examples
4922 Scale the input video to a size of 200x100:
4927 This is equivalent to:
4938 Specify a size abbreviation for the output size:
4943 which can also be written as:
4949 Scale the input to 2x:
4955 The above is the same as:
4961 Scale the input to 2x with forced interlaced scaling:
4963 scale=2*iw:2*ih:interl=1
4967 Scale the input to half size:
4973 Increase the width, and set the height to the same size:
4979 Seek for Greek harmony:
4986 Increase the height, and set the width to 3/2 of the height:
4988 scale=w=3/2*oh:h=3/5*ih
4992 Increase the size, but make the size a multiple of the chroma
4995 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4999 Increase the width to a maximum of 500 pixels, keep the same input
5002 scale=w='min(500\, iw*3/2):h=-1'
5006 @section separatefields
5008 The @code{separatefields} takes a frame-based video input and splits
5009 each frame into its components fields, producing a new half height clip
5010 with twice the frame rate and twice the frame count.
5012 This filter use field-dominance information in frame to decide which
5013 of each pair of fields to place first in the output.
5014 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
5016 @section setdar, setsar
5018 The @code{setdar} filter sets the Display Aspect Ratio for the filter
5021 This is done by changing the specified Sample (aka Pixel) Aspect
5022 Ratio, according to the following equation:
5024 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
5027 Keep in mind that the @code{setdar} filter does not modify the pixel
5028 dimensions of the video frame. Also the display aspect ratio set by
5029 this filter may be changed by later filters in the filterchain,
5030 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5033 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5034 the filter output video.
5036 Note that as a consequence of the application of this filter, the
5037 output display aspect ratio will change according to the equation
5040 Keep in mind that the sample aspect ratio set by the @code{setsar}
5041 filter may be changed by later filters in the filterchain, e.g. if
5042 another "setsar" or a "setdar" filter is applied.
5044 The @code{setdar} and @code{setsar} filters accept a string in the
5045 form @var{num}:@var{den} expressing an aspect ratio, or the following
5046 named options, expressed as a sequence of @var{key}=@var{value} pairs,
5051 Set the maximum integer value to use for expressing numerator and
5052 denominator when reducing the expressed aspect ratio to a rational.
5053 Default value is @code{100}.
5055 @item r, ratio, dar, sar:
5056 Set the aspect ratio used by the filter.
5058 The parameter can be a floating point number string, an expression, or
5059 a string of the form @var{num}:@var{den}, where @var{num} and
5060 @var{den} are the numerator and denominator of the aspect ratio. If
5061 the parameter is not specified, it is assumed the value "0".
5062 In case the form "@var{num}:@var{den}" the @code{:} character should
5066 If the keys are omitted in the named options list, the specifed values
5067 are assumed to be @var{ratio} and @var{max} in that order.
5069 For example to change the display aspect ratio to 16:9, specify:
5072 # the above is equivalent to
5078 To change the sample aspect ratio to 10:11, specify:
5081 # the above is equivalent to
5085 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5086 1000 in the aspect ratio reduction, use the command:
5088 setdar=ratio='16:9':max=1000
5094 Force field for the output video frame.
5096 The @code{setfield} filter marks the interlace type field for the
5097 output frames. It does not change the input frame, but only sets the
5098 corresponding property, which affects how the frame is treated by
5099 following filters (e.g. @code{fieldorder} or @code{yadif}).
5101 The filter accepts the following options:
5106 Available values are:
5110 Keep the same field property.
5113 Mark the frame as bottom-field-first.
5116 Mark the frame as top-field-first.
5119 Mark the frame as progressive.
5125 Show a line containing various information for each input video frame.
5126 The input video is not modified.
5128 The shown line contains a sequence of key/value pairs of the form
5129 @var{key}:@var{value}.
5131 A description of each shown parameter follows:
5135 sequential number of the input frame, starting from 0
5138 Presentation TimeStamp of the input frame, expressed as a number of
5139 time base units. The time base unit depends on the filter input pad.
5142 Presentation TimeStamp of the input frame, expressed as a number of
5146 position of the frame in the input stream, -1 if this information in
5147 unavailable and/or meaningless (for example in case of synthetic video)
5153 sample aspect ratio of the input frame, expressed in the form
5157 size of the input frame, expressed in the form
5158 @var{width}x@var{height}
5161 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5162 for bottom field first)
5165 1 if the frame is a key frame, 0 otherwise
5168 picture type of the input frame ("I" for an I-frame, "P" for a
5169 P-frame, "B" for a B-frame, "?" for unknown type).
5170 Check also the documentation of the @code{AVPictureType} enum and of
5171 the @code{av_get_picture_type_char} function defined in
5172 @file{libavutil/avutil.h}.
5175 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5177 @item plane_checksum
5178 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5179 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5184 Blur the input video without impacting the outlines.
5186 The filter accepts the following options:
5189 @item luma_radius, lr
5190 Set the luma radius. The option value must be a float number in
5191 the range [0.1,5.0] that specifies the variance of the gaussian filter
5192 used to blur the image (slower if larger). Default value is 1.0.
5194 @item luma_strength, ls
5195 Set the luma strength. The option value must be a float number
5196 in the range [-1.0,1.0] that configures the blurring. A value included
5197 in [0.0,1.0] will blur the image whereas a value included in
5198 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5200 @item luma_threshold, lt
5201 Set the luma threshold used as a coefficient to determine
5202 whether a pixel should be blurred or not. The option value must be an
5203 integer in the range [-30,30]. A value of 0 will filter all the image,
5204 a value included in [0,30] will filter flat areas and a value included
5205 in [-30,0] will filter edges. Default value is 0.
5207 @item chroma_radius, cr
5208 Set the chroma radius. The option value must be a float number in
5209 the range [0.1,5.0] that specifies the variance of the gaussian filter
5210 used to blur the image (slower if larger). Default value is 1.0.
5212 @item chroma_strength, cs
5213 Set the chroma strength. The option value must be a float number
5214 in the range [-1.0,1.0] that configures the blurring. A value included
5215 in [0.0,1.0] will blur the image whereas a value included in
5216 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5218 @item chroma_threshold, ct
5219 Set the chroma threshold used as a coefficient to determine
5220 whether a pixel should be blurred or not. The option value must be an
5221 integer in the range [-30,30]. A value of 0 will filter all the image,
5222 a value included in [0,30] will filter flat areas and a value included
5223 in [-30,0] will filter edges. Default value is 0.
5226 If a chroma option is not explicitly set, the corresponding luma value
5231 Convert between different stereoscopic image formats.
5233 The filters accept the following options:
5237 Set stereoscopic image format of input.
5239 Available values for input image formats are:
5242 side by side parallel (left eye left, right eye right)
5245 side by side crosseye (right eye left, left eye right)
5248 side by side parallel with half width resolution
5249 (left eye left, right eye right)
5252 side by side crosseye with half width resolution
5253 (right eye left, left eye right)
5256 above-below (left eye above, right eye below)
5259 above-below (right eye above, left eye below)
5262 above-below with half height resolution
5263 (left eye above, right eye below)
5266 above-below with half height resolution
5267 (right eye above, left eye below)
5269 Default value is @samp{sbsl}.
5273 Set stereoscopic image format of output.
5275 Available values for output image formats are all the input formats as well as:
5278 anaglyph red/blue gray
5279 (red filter on left eye, blue filter on right eye)
5282 anaglyph red/green gray
5283 (red filter on left eye, green filter on right eye)
5286 anaglyph red/cyan gray
5287 (red filter on left eye, cyan filter on right eye)
5290 anaglyph red/cyan half colored
5291 (red filter on left eye, cyan filter on right eye)
5294 anaglyph red/cyan color
5295 (red filter on left eye, cyan filter on right eye)
5298 anaglyph red/cyan color optimized with the least squares projection of dubois
5299 (red filter on left eye, cyan filter on right eye)
5302 anaglyph green/magenta gray
5303 (green filter on left eye, magenta filter on right eye)
5306 anaglyph green/magenta half colored
5307 (green filter on left eye, magenta filter on right eye)
5310 anaglyph green/magenta colored
5311 (green filter on left eye, magenta filter on right eye)
5314 anaglyph green/magenta color optimized with the least squares projection of dubois
5315 (green filter on left eye, magenta filter on right eye)
5318 anaglyph yellow/blue gray
5319 (yellow filter on left eye, blue filter on right eye)
5322 anaglyph yellow/blue half colored
5323 (yellow filter on left eye, blue filter on right eye)
5326 anaglyph yellow/blue colored
5327 (yellow filter on left eye, blue filter on right eye)
5330 anaglyph yellow/blue color optimized with the least squares projection of dubois
5331 (yellow filter on left eye, blue filter on right eye)
5334 interleaved rows (left eye has top row, right eye starts on next row)
5337 interleaved rows (right eye has top row, left eye starts on next row)
5340 mono output (left eye only)
5343 mono output (right eye only)
5346 Default value is @samp{arcd}.
5352 Draw subtitles on top of input video using the libass library.
5354 To enable compilation of this filter you need to configure FFmpeg with
5355 @code{--enable-libass}. This filter also requires a build with libavcodec and
5356 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5357 Alpha) subtitles format.
5359 The filter accepts the following options:
5363 Set the filename of the subtitle file to read. It must be specified.
5366 Specify the size of the original video, the video for which the ASS file
5367 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5368 necessary to correctly scale the fonts if the aspect ratio has been changed.
5371 Set subtitles input character encoding. @code{subtitles} filter only. Only
5372 useful if not UTF-8.
5375 If the first key is not specified, it is assumed that the first value
5376 specifies the @option{filename}.
5378 For example, to render the file @file{sub.srt} on top of the input
5379 video, use the command:
5384 which is equivalent to:
5386 subtitles=filename=sub.srt
5391 Split input video into several identical outputs.
5393 The filter accepts a single parameter which specifies the number of outputs. If
5394 unspecified, it defaults to 2.
5398 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5400 will create 5 copies of the input video.
5404 [in] split [splitout1][splitout2];
5405 [splitout1] crop=100:100:0:0 [cropout];
5406 [splitout2] pad=200:200:100:100 [padout];
5409 will create two separate outputs from the same input, one cropped and
5414 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5415 Interpolate) pixel art scaling algorithm.
5417 Useful for enlarging pixel art images without reducing sharpness.
5423 Select the most representative frame in a given sequence of consecutive frames.
5425 The filter accepts the following options:
5429 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5430 will pick one of them, and then handle the next batch of @var{n} frames until
5431 the end. Default is @code{100}.
5434 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5435 value will result in a higher memory usage, so a high value is not recommended.
5437 @subsection Examples
5441 Extract one picture each 50 frames:
5447 Complete example of a thumbnail creation with @command{ffmpeg}:
5449 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5455 Tile several successive frames together.
5457 The filter accepts the following options:
5462 Set the grid size (i.e. the number of lines and columns) in the form
5466 Set the maximum number of frames to render in the given area. It must be less
5467 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5468 the area will be used.
5471 Set the outer border margin in pixels.
5474 Set the inner border thickness (i.e. the number of pixels between frames). For
5475 more advanced padding options (such as having different values for the edges),
5476 refer to the pad video filter.
5480 @subsection Examples
5484 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5486 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5488 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5489 duplicating each output frame to accomodate the originally detected frame
5493 Display @code{5} pictures in an area of @code{3x2} frames,
5494 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5495 mixed flat and named options:
5497 tile=3x2:nb_frames=5:padding=7:margin=2
5503 Perform various types of temporal field interlacing.
5505 Frames are counted starting from 1, so the first input frame is
5508 The filter accepts the following options:
5513 Specify the mode of the interlacing. This option can also be specified
5514 as a value alone. See below for a list of values for this option.
5516 Available values are:
5520 Move odd frames into the upper field, even into the lower field,
5521 generating a double height frame at half frame rate.
5524 Only output even frames, odd frames are dropped, generating a frame with
5525 unchanged height at half frame rate.
5528 Only output odd frames, even frames are dropped, generating a frame with
5529 unchanged height at half frame rate.
5532 Expand each frame to full height, but pad alternate lines with black,
5533 generating a frame with double height at the same input frame rate.
5535 @item interleave_top, 4
5536 Interleave the upper field from odd frames with the lower field from
5537 even frames, generating a frame with unchanged height at half frame rate.
5539 @item interleave_bottom, 5
5540 Interleave the lower field from odd frames with the upper field from
5541 even frames, generating a frame with unchanged height at half frame rate.
5543 @item interlacex2, 6
5544 Double frame rate with unchanged height. Frames are inserted each
5545 containing the second temporal field from the previous input frame and
5546 the first temporal field from the next input frame. This mode relies on
5547 the top_field_first flag. Useful for interlaced video displays with no
5548 field synchronisation.
5551 Numeric values are deprecated but are accepted for backward
5552 compatibility reasons.
5554 Default mode is @code{merge}.
5557 Specify flags influencing the filter process.
5559 Available value for @var{flags} is:
5562 @item low_pass_filter, vlfp
5563 Enable vertical low-pass filtering in the filter.
5564 Vertical low-pass filtering is required when creating an interlaced
5565 destination from a progressive source which contains high-frequency
5566 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5569 Vertical low-pass filtering can only be enabled for @option{mode}
5570 @var{interleave_top} and @var{interleave_bottom}.
5577 Transpose rows with columns in the input video and optionally flip it.
5579 This filter accepts the following options:
5584 The direction of the transpose.
5587 @item 0, 4, cclock_flip
5588 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5596 Rotate by 90 degrees clockwise, that is:
5604 Rotate by 90 degrees counterclockwise, that is:
5611 @item 3, 7, clock_flip
5612 Rotate by 90 degrees clockwise and vertically flip, that is:
5620 For values between 4-7, the transposition is only done if the input
5621 video geometry is portrait and not landscape. These values are
5622 deprecated, the @code{passthrough} option should be used instead.
5625 Do not apply the transposition if the input geometry matches the one
5626 specified by the specified value. It accepts the following values:
5629 Always apply transposition.
5631 Preserve portrait geometry (when @var{height} >= @var{width}).
5633 Preserve landscape geometry (when @var{width} >= @var{height}).
5636 Default value is @code{none}.
5639 For example to rotate by 90 degrees clockwise and preserve portrait
5642 transpose=dir=1:passthrough=portrait
5645 The command above can also be specified as:
5647 transpose=1:portrait
5652 Sharpen or blur the input video.
5654 It accepts the following parameters:
5657 @item luma_msize_x, lx
5658 @item chroma_msize_x, cx
5659 Set the luma/chroma matrix horizontal size. It must be an odd integer
5660 between 3 and 63, default value is 5.
5662 @item luma_msize_y, ly
5663 @item chroma_msize_y, cy
5664 Set the luma/chroma matrix vertical size. It must be an odd integer
5665 between 3 and 63, default value is 5.
5667 @item luma_amount, la
5668 @item chroma_amount, ca
5669 Set the luma/chroma effect strength. It can be a float number,
5670 reasonable values lay between -1.5 and 1.5.
5672 Negative values will blur the input video, while positive values will
5673 sharpen it, a value of zero will disable the effect.
5675 Default value is 1.0 for @option{luma_amount}, 0.0 for
5676 @option{chroma_amount}.
5679 All parameters are optional and default to the
5680 equivalent of the string '5:5:1.0:5:5:0.0'.
5682 @subsection Examples
5686 Apply strong luma sharpen effect:
5688 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5692 Apply strong blur of both luma and chroma parameters:
5694 unsharp=7:7:-2:7:7:-2
5700 Flip the input video vertically.
5703 ffmpeg -i in.avi -vf "vflip" out.avi
5708 Deinterlace the input video ("yadif" means "yet another deinterlacing
5711 This filter accepts the following options:
5717 The interlacing mode to adopt, accepts one of the following values:
5721 output 1 frame for each frame
5723 output 1 frame for each field
5724 @item 2, send_frame_nospatial
5725 like @code{send_frame} but skip spatial interlacing check
5726 @item 3, send_field_nospatial
5727 like @code{send_field} but skip spatial interlacing check
5730 Default value is @code{send_frame}.
5733 The picture field parity assumed for the input interlaced video, accepts one of
5734 the following values:
5738 assume top field first
5740 assume bottom field first
5742 enable automatic detection
5745 Default value is @code{auto}.
5746 If interlacing is unknown or decoder does not export this information,
5747 top field first will be assumed.
5750 Specify which frames to deinterlace. Accept one of the following
5755 deinterlace all frames
5757 only deinterlace frames marked as interlaced
5760 Default value is @code{all}.
5763 @c man end VIDEO FILTERS
5765 @chapter Video Sources
5766 @c man begin VIDEO SOURCES
5768 Below is a description of the currently available video sources.
5772 Buffer video frames, and make them available to the filter chain.
5774 This source is mainly intended for a programmatic use, in particular
5775 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5777 It accepts a list of options in the form of @var{key}=@var{value} pairs
5778 separated by ":". A description of the accepted options follows.
5783 Specify the size (width and height) of the buffered video frames.
5786 A string representing the pixel format of the buffered video frames.
5787 It may be a number corresponding to a pixel format, or a pixel format
5791 Specify the timebase assumed by the timestamps of the buffered frames.
5794 Specify the frame rate expected for the video stream.
5797 Specify the sample aspect ratio assumed by the video frames.
5800 Specify the optional parameters to be used for the scale filter which
5801 is automatically inserted when an input change is detected in the
5802 input size or format.
5807 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5810 will instruct the source to accept video frames with size 320x240 and
5811 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5812 square pixels (1:1 sample aspect ratio).
5813 Since the pixel format with name "yuv410p" corresponds to the number 6
5814 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5815 this example corresponds to:
5817 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5820 Alternatively, the options can be specified as a flat string, but this
5821 syntax is deprecated:
5823 @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}]
5827 Create a pattern generated by an elementary cellular automaton.
5829 The initial state of the cellular automaton can be defined through the
5830 @option{filename}, and @option{pattern} options. If such options are
5831 not specified an initial state is created randomly.
5833 At each new frame a new row in the video is filled with the result of
5834 the cellular automaton next generation. The behavior when the whole
5835 frame is filled is defined by the @option{scroll} option.
5837 This source accepts the following options:
5841 Read the initial cellular automaton state, i.e. the starting row, from
5843 In the file, each non-whitespace character is considered an alive
5844 cell, a newline will terminate the row, and further characters in the
5845 file will be ignored.
5848 Read the initial cellular automaton state, i.e. the starting row, from
5849 the specified string.
5851 Each non-whitespace character in the string is considered an alive
5852 cell, a newline will terminate the row, and further characters in the
5853 string will be ignored.
5856 Set the video rate, that is the number of frames generated per second.
5859 @item random_fill_ratio, ratio
5860 Set the random fill ratio for the initial cellular automaton row. It
5861 is a floating point number value ranging from 0 to 1, defaults to
5864 This option is ignored when a file or a pattern is specified.
5866 @item random_seed, seed
5867 Set the seed for filling randomly the initial row, must be an integer
5868 included between 0 and UINT32_MAX. If not specified, or if explicitly
5869 set to -1, the filter will try to use a good random seed on a best
5873 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5874 Default value is 110.
5877 Set the size of the output video.
5879 If @option{filename} or @option{pattern} is specified, the size is set
5880 by default to the width of the specified initial state row, and the
5881 height is set to @var{width} * PHI.
5883 If @option{size} is set, it must contain the width of the specified
5884 pattern string, and the specified pattern will be centered in the
5887 If a filename or a pattern string is not specified, the size value
5888 defaults to "320x518" (used for a randomly generated initial state).
5891 If set to 1, scroll the output upward when all the rows in the output
5892 have been already filled. If set to 0, the new generated row will be
5893 written over the top row just after the bottom row is filled.
5896 @item start_full, full
5897 If set to 1, completely fill the output with generated rows before
5898 outputting the first frame.
5899 This is the default behavior, for disabling set the value to 0.
5902 If set to 1, stitch the left and right row edges together.
5903 This is the default behavior, for disabling set the value to 0.
5906 @subsection Examples
5910 Read the initial state from @file{pattern}, and specify an output of
5913 cellauto=f=pattern:s=200x400
5917 Generate a random initial row with a width of 200 cells, with a fill
5920 cellauto=ratio=2/3:s=200x200
5924 Create a pattern generated by rule 18 starting by a single alive cell
5925 centered on an initial row with width 100:
5927 cellauto=p=@@:s=100x400:full=0:rule=18
5931 Specify a more elaborated initial pattern:
5933 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5940 Generate a Mandelbrot set fractal, and progressively zoom towards the
5941 point specified with @var{start_x} and @var{start_y}.
5943 This source accepts the following options:
5948 Set the terminal pts value. Default value is 400.
5951 Set the terminal scale value.
5952 Must be a floating point value. Default value is 0.3.
5955 Set the inner coloring mode, that is the algorithm used to draw the
5956 Mandelbrot fractal internal region.
5958 It shall assume one of the following values:
5963 Show time until convergence.
5965 Set color based on point closest to the origin of the iterations.
5970 Default value is @var{mincol}.
5973 Set the bailout value. Default value is 10.0.
5976 Set the maximum of iterations performed by the rendering
5977 algorithm. Default value is 7189.
5980 Set outer coloring mode.
5981 It shall assume one of following values:
5983 @item iteration_count
5984 Set iteration cound mode.
5985 @item normalized_iteration_count
5986 set normalized iteration count mode.
5988 Default value is @var{normalized_iteration_count}.
5991 Set frame rate, expressed as number of frames per second. Default
5995 Set frame size. Default value is "640x480".
5998 Set the initial scale value. Default value is 3.0.
6001 Set the initial x position. Must be a floating point value between
6002 -100 and 100. Default value is -0.743643887037158704752191506114774.
6005 Set the initial y position. Must be a floating point value between
6006 -100 and 100. Default value is -0.131825904205311970493132056385139.
6011 Generate various test patterns, as generated by the MPlayer test filter.
6013 The size of the generated video is fixed, and is 256x256.
6014 This source is useful in particular for testing encoding features.
6016 This source accepts the following options:
6021 Specify the frame rate of the sourced video, as the number of frames
6022 generated per second. It has to be a string in the format
6023 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6024 number or a valid video frame rate abbreviation. The default value is
6028 Set the video duration of the sourced video. The accepted syntax is:
6033 See also the function @code{av_parse_time()}.
6035 If not specified, or the expressed duration is negative, the video is
6036 supposed to be generated forever.
6040 Set the number or the name of the test to perform. Supported tests are:
6055 Default value is "all", which will cycle through the list of all tests.
6058 For example the following:
6063 will generate a "dc_luma" test pattern.
6067 Provide a frei0r source.
6069 To enable compilation of this filter you need to install the frei0r
6070 header and configure FFmpeg with @code{--enable-frei0r}.
6072 This source accepts the following options:
6077 The size of the video to generate, may be a string of the form
6078 @var{width}x@var{height} or a frame size abbreviation.
6081 Framerate of the generated video, may be a string of the form
6082 @var{num}/@var{den} or a frame rate abbreviation.
6085 The name to the frei0r source to load. For more information regarding frei0r and
6086 how to set the parameters read the section @ref{frei0r} in the description of
6090 A '|'-separated list of parameters to pass to the frei0r source.
6094 For example, to generate a frei0r partik0l source with size 200x200
6095 and frame rate 10 which is overlayed on the overlay filter main input:
6097 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6102 Generate a life pattern.
6104 This source is based on a generalization of John Conway's life game.
6106 The sourced input represents a life grid, each pixel represents a cell
6107 which can be in one of two possible states, alive or dead. Every cell
6108 interacts with its eight neighbours, which are the cells that are
6109 horizontally, vertically, or diagonally adjacent.
6111 At each interaction the grid evolves according to the adopted rule,
6112 which specifies the number of neighbor alive cells which will make a
6113 cell stay alive or born. The @option{rule} option allows to specify
6116 This source accepts the following options:
6120 Set the file from which to read the initial grid state. In the file,
6121 each non-whitespace character is considered an alive cell, and newline
6122 is used to delimit the end of each row.
6124 If this option is not specified, the initial grid is generated
6128 Set the video rate, that is the number of frames generated per second.
6131 @item random_fill_ratio, ratio
6132 Set the random fill ratio for the initial random grid. It is a
6133 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6134 It is ignored when a file is specified.
6136 @item random_seed, seed
6137 Set the seed for filling the initial random grid, must be an integer
6138 included between 0 and UINT32_MAX. If not specified, or if explicitly
6139 set to -1, the filter will try to use a good random seed on a best
6145 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6146 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6147 @var{NS} specifies the number of alive neighbor cells which make a
6148 live cell stay alive, and @var{NB} the number of alive neighbor cells
6149 which make a dead cell to become alive (i.e. to "born").
6150 "s" and "b" can be used in place of "S" and "B", respectively.
6152 Alternatively a rule can be specified by an 18-bits integer. The 9
6153 high order bits are used to encode the next cell state if it is alive
6154 for each number of neighbor alive cells, the low order bits specify
6155 the rule for "borning" new cells. Higher order bits encode for an
6156 higher number of neighbor cells.
6157 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6158 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6160 Default value is "S23/B3", which is the original Conway's game of life
6161 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6162 cells, and will born a new cell if there are three alive cells around
6166 Set the size of the output video.
6168 If @option{filename} is specified, the size is set by default to the
6169 same size of the input file. If @option{size} is set, it must contain
6170 the size specified in the input file, and the initial grid defined in
6171 that file is centered in the larger resulting area.
6173 If a filename is not specified, the size value defaults to "320x240"
6174 (used for a randomly generated initial grid).
6177 If set to 1, stitch the left and right grid edges together, and the
6178 top and bottom edges also. Defaults to 1.
6181 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6182 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6183 value from 0 to 255.
6186 Set the color of living (or new born) cells.
6189 Set the color of dead cells. If @option{mold} is set, this is the first color
6190 used to represent a dead cell.
6193 Set mold color, for definitely dead and moldy cells.
6196 @subsection Examples
6200 Read a grid from @file{pattern}, and center it on a grid of size
6203 life=f=pattern:s=300x300
6207 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6209 life=ratio=2/3:s=200x200
6213 Specify a custom rule for evolving a randomly generated grid:
6219 Full example with slow death effect (mold) using @command{ffplay}:
6221 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6225 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6227 The @code{color} source provides an uniformly colored input.
6229 The @code{nullsrc} source returns unprocessed video frames. It is
6230 mainly useful to be employed in analysis / debugging tools, or as the
6231 source for filters which ignore the input data.
6233 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6234 detecting RGB vs BGR issues. You should see a red, green and blue
6235 stripe from top to bottom.
6237 The @code{smptebars} source generates a color bars pattern, based on
6238 the SMPTE Engineering Guideline EG 1-1990.
6240 The @code{testsrc} source generates a test video pattern, showing a
6241 color pattern, a scrolling gradient and a timestamp. This is mainly
6242 intended for testing purposes.
6244 The sources accept the following options:
6249 Specify the color of the source, only used in the @code{color}
6250 source. It can be the name of a color (case insensitive match) or a
6251 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6252 default value is "black".
6255 Specify the size of the sourced video, it may be a string of the form
6256 @var{width}x@var{height}, or the name of a size abbreviation. The
6257 default value is "320x240".
6260 Specify the frame rate of the sourced video, as the number of frames
6261 generated per second. It has to be a string in the format
6262 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6263 number or a valid video frame rate abbreviation. The default value is
6267 Set the sample aspect ratio of the sourced video.
6270 Set the video duration of the sourced video. The accepted syntax is:
6272 [-]HH[:MM[:SS[.m...]]]
6275 See also the function @code{av_parse_time()}.
6277 If not specified, or the expressed duration is negative, the video is
6278 supposed to be generated forever.
6281 Set the number of decimals to show in the timestamp, only used in the
6282 @code{testsrc} source.
6284 The displayed timestamp value will correspond to the original
6285 timestamp value multiplied by the power of 10 of the specified
6286 value. Default value is 0.
6289 For example the following:
6291 testsrc=duration=5.3:size=qcif:rate=10
6294 will generate a video with a duration of 5.3 seconds, with size
6295 176x144 and a frame rate of 10 frames per second.
6297 The following graph description will generate a red source
6298 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6301 color=c=red@@0.2:s=qcif:r=10
6304 If the input content is to be ignored, @code{nullsrc} can be used. The
6305 following command generates noise in the luminance plane by employing
6306 the @code{geq} filter:
6308 nullsrc=s=256x256, geq=random(1)*255:128:128
6311 @c man end VIDEO SOURCES
6313 @chapter Video Sinks
6314 @c man begin VIDEO SINKS
6316 Below is a description of the currently available video sinks.
6320 Buffer video frames, and make them available to the end of the filter
6323 This sink is mainly intended for a programmatic use, in particular
6324 through the interface defined in @file{libavfilter/buffersink.h}.
6326 It does not require a string parameter in input, but you need to
6327 specify a pointer to a list of supported pixel formats terminated by
6328 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6329 when initializing this sink.
6333 Null video sink, do absolutely nothing with the input video. It is
6334 mainly useful as a template and to be employed in analysis / debugging
6337 @c man end VIDEO SINKS
6339 @chapter Multimedia Filters
6340 @c man begin MULTIMEDIA FILTERS
6342 Below is a description of the currently available multimedia filters.
6344 @section aperms, perms
6346 Set read/write permissions for the output frames.
6348 These filters are mainly aimed at developers to test direct path in the
6349 following filter in the filtergraph.
6351 The filters accept the following options:
6355 Select the permissions mode.
6357 It accepts the following values:
6360 Do nothing. This is the default.
6362 Set all the output frames read-only.
6364 Set all the output frames directly writable.
6366 Make the frame read-only if writable, and writable if read-only.
6368 Set each output frame read-only or writable randomly.
6372 Set the seed for the @var{random} mode, must be an integer included between
6373 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6374 @code{-1}, the filter will try to use a good random seed on a best effort
6378 Note: in case of auto-inserted filter between the permission filter and the
6379 following one, the permission might not be received as expected in that
6380 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6381 perms/aperms filter can avoid this problem.
6384 Add a phasing effect to the input audio.
6386 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6387 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6389 A description of the accepted parameters follows.
6393 Set input gain. Default is 0.4.
6396 Set output gain. Default is 0.74
6399 Set delay in milliseconds. Default is 3.0.
6402 Set decay. Default is 0.4.
6405 Set modulation speed in Hz. Default is 0.5.
6408 Set modulation type. Default is triangular.
6410 It accepts the following values:
6417 @section aselect, select
6418 Select frames to pass in output.
6420 This filter accepts the following options:
6425 An expression, which is evaluated for each input frame. If the expression is
6426 evaluated to a non-zero value, the frame is selected and passed to the output,
6427 otherwise it is discarded.
6431 The expression can contain the following constants:
6435 the sequential number of the filtered frame, starting from 0
6438 the sequential number of the selected frame, starting from 0
6440 @item prev_selected_n
6441 the sequential number of the last selected frame, NAN if undefined
6444 timebase of the input timestamps
6447 the PTS (Presentation TimeStamp) of the filtered video frame,
6448 expressed in @var{TB} units, NAN if undefined
6451 the PTS (Presentation TimeStamp) of the filtered video frame,
6452 expressed in seconds, NAN if undefined
6455 the PTS of the previously filtered video frame, NAN if undefined
6457 @item prev_selected_pts
6458 the PTS of the last previously filtered video frame, NAN if undefined
6460 @item prev_selected_t
6461 the PTS of the last previously selected video frame, NAN if undefined
6464 the PTS of the first video frame in the video, NAN if undefined
6467 the time of the first video frame in the video, NAN if undefined
6469 @item pict_type @emph{(video only)}
6470 the type of the filtered frame, can assume one of the following
6482 @item interlace_type @emph{(video only)}
6483 the frame interlace type, can assume one of the following values:
6486 the frame is progressive (not interlaced)
6488 the frame is top-field-first
6490 the frame is bottom-field-first
6493 @item consumed_sample_n @emph{(audio only)}
6494 the number of selected samples before the current frame
6496 @item samples_n @emph{(audio only)}
6497 the number of samples in the current frame
6499 @item sample_rate @emph{(audio only)}
6500 the input sample rate
6503 1 if the filtered frame is a key-frame, 0 otherwise
6506 the position in the file of the filtered frame, -1 if the information
6507 is not available (e.g. for synthetic video)
6509 @item scene @emph{(video only)}
6510 value between 0 and 1 to indicate a new scene; a low value reflects a low
6511 probability for the current frame to introduce a new scene, while a higher
6512 value means the current frame is more likely to be one (see the example below)
6516 The default value of the select expression is "1".
6518 @subsection Examples
6522 Select all frames in input:
6527 The example above is the same as:
6539 Select only I-frames:
6541 select='eq(pict_type\,I)'
6545 Select one frame every 100:
6547 select='not(mod(n\,100))'
6551 Select only frames contained in the 10-20 time interval:
6553 select='gte(t\,10)*lte(t\,20)'
6557 Select only I frames contained in the 10-20 time interval:
6559 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6563 Select frames with a minimum distance of 10 seconds:
6565 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6569 Use aselect to select only audio frames with samples number > 100:
6571 aselect='gt(samples_n\,100)'
6575 Create a mosaic of the first scenes:
6577 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6580 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6584 @section asendcmd, sendcmd
6586 Send commands to filters in the filtergraph.
6588 These filters read commands to be sent to other filters in the
6591 @code{asendcmd} must be inserted between two audio filters,
6592 @code{sendcmd} must be inserted between two video filters, but apart
6593 from that they act the same way.
6595 The specification of commands can be provided in the filter arguments
6596 with the @var{commands} option, or in a file specified by the
6597 @var{filename} option.
6599 These filters accept the following options:
6602 Set the commands to be read and sent to the other filters.
6604 Set the filename of the commands to be read and sent to the other
6608 @subsection Commands syntax
6610 A commands description consists of a sequence of interval
6611 specifications, comprising a list of commands to be executed when a
6612 particular event related to that interval occurs. The occurring event
6613 is typically the current frame time entering or leaving a given time
6616 An interval is specified by the following syntax:
6618 @var{START}[-@var{END}] @var{COMMANDS};
6621 The time interval is specified by the @var{START} and @var{END} times.
6622 @var{END} is optional and defaults to the maximum time.
6624 The current frame time is considered within the specified interval if
6625 it is included in the interval [@var{START}, @var{END}), that is when
6626 the time is greater or equal to @var{START} and is lesser than
6629 @var{COMMANDS} consists of a sequence of one or more command
6630 specifications, separated by ",", relating to that interval. The
6631 syntax of a command specification is given by:
6633 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6636 @var{FLAGS} is optional and specifies the type of events relating to
6637 the time interval which enable sending the specified command, and must
6638 be a non-null sequence of identifier flags separated by "+" or "|" and
6639 enclosed between "[" and "]".
6641 The following flags are recognized:
6644 The command is sent when the current frame timestamp enters the
6645 specified interval. In other words, the command is sent when the
6646 previous frame timestamp was not in the given interval, and the
6650 The command is sent when the current frame timestamp leaves the
6651 specified interval. In other words, the command is sent when the
6652 previous frame timestamp was in the given interval, and the
6656 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6659 @var{TARGET} specifies the target of the command, usually the name of
6660 the filter class or a specific filter instance name.
6662 @var{COMMAND} specifies the name of the command for the target filter.
6664 @var{ARG} is optional and specifies the optional list of argument for
6665 the given @var{COMMAND}.
6667 Between one interval specification and another, whitespaces, or
6668 sequences of characters starting with @code{#} until the end of line,
6669 are ignored and can be used to annotate comments.
6671 A simplified BNF description of the commands specification syntax
6674 @var{COMMAND_FLAG} ::= "enter" | "leave"
6675 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6676 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6677 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6678 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6679 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6682 @subsection Examples
6686 Specify audio tempo change at second 4:
6688 asendcmd=c='4.0 atempo tempo 1.5',atempo
6692 Specify a list of drawtext and hue commands in a file.
6694 # show text in the interval 5-10
6695 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6696 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6698 # desaturate the image in the interval 15-20
6699 15.0-20.0 [enter] hue reinit s=0,
6700 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6701 [leave] hue reinit s=1,
6702 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6704 # apply an exponential saturation fade-out effect, starting from time 25
6705 25 [enter] hue s=exp(t-25)
6708 A filtergraph allowing to read and process the above command list
6709 stored in a file @file{test.cmd}, can be specified with:
6711 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6716 @section asetpts, setpts
6718 Change the PTS (presentation timestamp) of the input frames.
6720 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6722 This filter accepts the following options:
6727 The expression which is evaluated for each frame to construct its timestamp.
6731 The expression is evaluated through the eval API and can contain the following
6736 frame rate, only defined for constant frame-rate video
6739 the presentation timestamp in input
6742 the count of the input frame, starting from 0.
6744 @item NB_CONSUMED_SAMPLES
6745 the number of consumed samples, not including the current frame (only
6749 the number of samples in the current frame (only audio)
6755 the PTS of the first frame
6758 the time in seconds of the first frame
6761 tell if the current frame is interlaced
6764 the time in seconds of the current frame
6770 original position in the file of the frame, or undefined if undefined
6771 for the current frame
6777 previous input time in seconds
6783 previous output time in seconds
6786 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6790 wallclock (RTC) time at the start of the movie in microseconds
6793 @subsection Examples
6797 Start counting PTS from zero
6803 Apply fast motion effect:
6809 Apply slow motion effect:
6815 Set fixed rate of 25 frames per second:
6821 Set fixed rate 25 fps with some jitter:
6823 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6827 Apply an offset of 10 seconds to the input PTS:
6833 Generate timestamps from a "live source" and rebase onto the current timebase:
6835 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6841 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6842 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6843 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6844 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6846 The filter also has a video output (see the @var{video} option) with a real
6847 time graph to observe the loudness evolution. The graphic contains the logged
6848 message mentioned above, so it is not printed anymore when this option is set,
6849 unless the verbose logging is set. The main graphing area contains the
6850 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6851 the momentary loudness (400 milliseconds).
6853 More information about the Loudness Recommendation EBU R128 on
6854 @url{http://tech.ebu.ch/loudness}.
6856 The filter accepts the following options:
6861 Activate the video output. The audio stream is passed unchanged whether this
6862 option is set or no. The video stream will be the first output stream if
6863 activated. Default is @code{0}.
6866 Set the video size. This option is for video only. Default and minimum
6867 resolution is @code{640x480}.
6870 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6871 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6872 other integer value between this range is allowed.
6875 Set metadata injection. If set to @code{1}, the audio input will be segmented
6876 into 100ms output frames, each of them containing various loudness information
6877 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6879 Default is @code{0}.
6882 Force the frame logging level.
6884 Available values are:
6887 information logging level
6889 verbose logging level
6892 By default, the logging level is set to @var{info}. If the @option{video} or
6893 the @option{metadata} options are set, it switches to @var{verbose}.
6896 @subsection Examples
6900 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6902 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6906 Run an analysis with @command{ffmpeg}:
6908 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6912 @section settb, asettb
6914 Set the timebase to use for the output frames timestamps.
6915 It is mainly useful for testing timebase configuration.
6917 This filter accepts the following options:
6922 The expression which is evaluated into the output timebase.
6926 The value for @option{tb} is an arithmetic expression representing a
6927 rational. The expression can contain the constants "AVTB" (the default
6928 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6929 audio only). Default value is "intb".
6931 @subsection Examples
6935 Set the timebase to 1/25:
6941 Set the timebase to 1/10:
6947 Set the timebase to 1001/1000:
6953 Set the timebase to 2*intb:
6959 Set the default timebase value:
6967 Concatenate audio and video streams, joining them together one after the
6970 The filter works on segments of synchronized video and audio streams. All
6971 segments must have the same number of streams of each type, and that will
6972 also be the number of streams at output.
6974 The filter accepts the following options:
6979 Set the number of segments. Default is 2.
6982 Set the number of output video streams, that is also the number of video
6983 streams in each segment. Default is 1.
6986 Set the number of output audio streams, that is also the number of video
6987 streams in each segment. Default is 0.
6990 Activate unsafe mode: do not fail if segments have a different format.
6994 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6995 @var{a} audio outputs.
6997 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6998 segment, in the same order as the outputs, then the inputs for the second
7001 Related streams do not always have exactly the same duration, for various
7002 reasons including codec frame size or sloppy authoring. For that reason,
7003 related synchronized streams (e.g. a video and its audio track) should be
7004 concatenated at once. The concat filter will use the duration of the longest
7005 stream in each segment (except the last one), and if necessary pad shorter
7006 audio streams with silence.
7008 For this filter to work correctly, all segments must start at timestamp 0.
7010 All corresponding streams must have the same parameters in all segments; the
7011 filtering system will automatically select a common pixel format for video
7012 streams, and a common sample format, sample rate and channel layout for
7013 audio streams, but other settings, such as resolution, must be converted
7014 explicitly by the user.
7016 Different frame rates are acceptable but will result in variable frame rate
7017 at output; be sure to configure the output file to handle it.
7019 @subsection Examples
7023 Concatenate an opening, an episode and an ending, all in bilingual version
7024 (video in stream 0, audio in streams 1 and 2):
7026 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
7027 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7028 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7029 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7033 Concatenate two parts, handling audio and video separately, using the
7034 (a)movie sources, and adjusting the resolution:
7036 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7037 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7038 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7040 Note that a desync will happen at the stitch if the audio and video streams
7041 do not have exactly the same duration in the first file.
7045 @section showspectrum
7047 Convert input audio to a video output, representing the audio frequency
7050 The filter accepts the following options:
7054 Specify the video size for the output. Default value is @code{640x512}.
7057 Specify if the spectrum should slide along the window. Default value is
7061 Specify display mode.
7063 It accepts the following values:
7066 all channels are displayed in the same row
7068 all channels are displayed in separate rows
7071 Default value is @samp{combined}.
7074 Specify display color mode.
7076 It accepts the following values:
7079 each channel is displayed in a separate color
7081 each channel is is displayed using the same color scheme
7084 Default value is @samp{channel}.
7087 Specify scale used for calculating intensity color values.
7089 It accepts the following values:
7094 square root, default
7101 Default value is @samp{sqrt}.
7104 Set saturation modifier for displayed colors. Negative values provide
7105 alternative color scheme. @code{0} is no saturation at all.
7106 Saturation must be in [-10.0, 10.0] range.
7107 Default value is @code{1}.
7110 The usage is very similar to the showwaves filter; see the examples in that
7113 @subsection Examples
7117 Large window with logarithmic color scaling:
7119 showspectrum=s=1280x480:scale=log
7123 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7125 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7126 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7132 Convert input audio to a video output, representing the samples waves.
7134 The filter accepts the following named parameters:
7139 Available values are:
7142 Draw a point for each sample.
7145 Draw a vertical line for each sample.
7148 Default value is @code{point}.
7151 Set the number of samples which are printed on the same column. A
7152 larger value will decrease the frame rate. Must be a positive
7153 integer. This option can be set only if the value for @var{rate}
7154 is not explicitly specified.
7157 Set the (approximate) output frame rate. This is done by setting the
7158 option @var{n}. Default value is "25".
7161 Specify the video size for the output. Default value is "600x240".
7164 @subsection Examples
7168 Output the input file audio and the corresponding video representation
7171 amovie=a.mp3,asplit[out0],showwaves[out1]
7175 Create a synthetic signal and show it with showwaves, forcing a
7176 frame rate of 30 frames per second:
7178 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7182 @c man end MULTIMEDIA FILTERS
7184 @chapter Multimedia Sources
7185 @c man begin MULTIMEDIA SOURCES
7187 Below is a description of the currently available multimedia sources.
7191 This is the same as @ref{movie} source, except it selects an audio
7197 Read audio and/or video stream(s) from a movie container.
7199 This filter accepts the following options:
7203 The name of the resource to read (not necessarily a file but also a device or a
7204 stream accessed through some protocol).
7206 @item format_name, f
7207 Specifies the format assumed for the movie to read, and can be either
7208 the name of a container or an input device. If not specified the
7209 format is guessed from @var{movie_name} or by probing.
7211 @item seek_point, sp
7212 Specifies the seek point in seconds, the frames will be output
7213 starting from this seek point, the parameter is evaluated with
7214 @code{av_strtod} so the numerical value may be suffixed by an IS
7215 postfix. Default value is "0".
7218 Specifies the streams to read. Several streams can be specified,
7219 separated by "+". The source will then have as many outputs, in the
7220 same order. The syntax is explained in the ``Stream specifiers''
7221 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7222 respectively the default (best suited) video and audio stream. Default
7223 is "dv", or "da" if the filter is called as "amovie".
7225 @item stream_index, si
7226 Specifies the index of the video stream to read. If the value is -1,
7227 the best suited video stream will be automatically selected. Default
7228 value is "-1". Deprecated. If the filter is called "amovie", it will select
7229 audio instead of video.
7232 Specifies how many times to read the stream in sequence.
7233 If the value is less than 1, the stream will be read again and again.
7234 Default value is "1".
7236 Note that when the movie is looped the source timestamps are not
7237 changed, so it will generate non monotonically increasing timestamps.
7240 This filter allows to overlay a second video on top of main input of
7241 a filtergraph as shown in this graph:
7243 input -----------> deltapts0 --> overlay --> output
7246 movie --> scale--> deltapts1 -------+
7249 @subsection Examples
7253 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7254 on top of the input labelled as "in":
7256 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7257 [in] setpts=PTS-STARTPTS [main];
7258 [main][over] overlay=16:16 [out]
7262 Read from a video4linux2 device, and overlay it on top of the input
7265 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7266 [in] setpts=PTS-STARTPTS [main];
7267 [main][over] overlay=16:16 [out]
7271 Read the first video stream and the audio stream with id 0x81 from
7272 dvd.vob; the video is connected to the pad named "video" and the audio is
7273 connected to the pad named "audio":
7275 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7279 @c man end MULTIMEDIA SOURCES