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 filter accepts the following options:
1006 Set the expression deciding which stream should be
1007 forwarded next: if the result is negative, the first stream is forwarded; if
1008 the result is positive or zero, the second stream is forwarded. It can use
1009 the following variables:
1013 number of buffers forwarded so far on each stream
1015 number of samples forwarded so far on each stream
1017 current timestamp of each stream
1020 The default value is @code{t1-t2}, which means to always forward the stream
1021 that has a smaller timestamp.
1024 @subsection Examples
1026 Stress-test @code{amerge} by randomly sending buffers on the wrong
1027 input, while avoiding too much of a desynchronization:
1029 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1030 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1038 The filter accepts exactly one parameter, the audio tempo. If not
1039 specified then the filter will assume nominal 1.0 tempo. Tempo must
1040 be in the [0.5, 2.0] range.
1042 @subsection Examples
1046 Slow down audio to 80% tempo:
1052 To speed up audio to 125% tempo:
1060 Make audio easier to listen to on headphones.
1062 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1063 so that when listened to on headphones the stereo image is moved from
1064 inside your head (standard for headphones) to outside and in front of
1065 the listener (standard for speakers).
1071 Mix channels with specific gain levels. The filter accepts the output
1072 channel layout followed by a set of channels definitions.
1074 This filter is also designed to remap efficiently the channels of an audio
1077 The filter accepts parameters of the form:
1078 "@var{l}:@var{outdef}:@var{outdef}:..."
1082 output channel layout or number of channels
1085 output channel specification, of the form:
1086 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1089 output channel to define, either a channel name (FL, FR, etc.) or a channel
1090 number (c0, c1, etc.)
1093 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1096 input channel to use, see out_name for details; it is not possible to mix
1097 named and numbered input channels
1100 If the `=' in a channel specification is replaced by `<', then the gains for
1101 that specification will be renormalized so that the total is 1, thus
1102 avoiding clipping noise.
1104 @subsection Mixing examples
1106 For example, if you want to down-mix from stereo to mono, but with a bigger
1107 factor for the left channel:
1109 pan=1:c0=0.9*c0+0.1*c1
1112 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1113 7-channels surround:
1115 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1118 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1119 that should be preferred (see "-ac" option) unless you have very specific
1122 @subsection Remapping examples
1124 The channel remapping will be effective if, and only if:
1127 @item gain coefficients are zeroes or ones,
1128 @item only one input per channel output,
1131 If all these conditions are satisfied, the filter will notify the user ("Pure
1132 channel mapping detected"), and use an optimized and lossless method to do the
1135 For example, if you have a 5.1 source and want a stereo audio stream by
1136 dropping the extra channels:
1138 pan="stereo: c0=FL : c1=FR"
1141 Given the same source, you can also switch front left and front right channels
1142 and keep the input channel layout:
1144 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1147 If the input is a stereo audio stream, you can mute the front left channel (and
1148 still keep the stereo channel layout) with:
1153 Still with a stereo audio stream input, you can copy the right channel in both
1154 front left and right:
1156 pan="stereo: c0=FR : c1=FR"
1159 @section silencedetect
1161 Detect silence in an audio stream.
1163 This filter logs a message when it detects that the input audio volume is less
1164 or equal to a noise tolerance value for a duration greater or equal to the
1165 minimum detected noise duration.
1167 The printed times and duration are expressed in seconds.
1169 The filter accepts the following options:
1173 Set silence duration until notification (default is 2 seconds).
1176 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1177 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1180 @subsection Examples
1184 Detect 5 seconds of silence with -50dB noise tolerance:
1186 silencedetect=n=-50dB:d=5
1190 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1191 tolerance in @file{silence.mp3}:
1193 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1198 Synchronize audio data with timestamps by squeezing/stretching it and/or
1199 dropping samples/adding silence when needed.
1201 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1203 The filter accepts the following named parameters:
1207 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1208 by default. When disabled, time gaps are covered with silence.
1211 Minimum difference between timestamps and audio data (in seconds) to trigger
1212 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1213 this filter, try setting this parameter to 0.
1216 Maximum compensation in samples per second. Relevant only with compensate=1.
1220 Assume the first pts should be this value. The time base is 1 / sample rate.
1221 This allows for padding/trimming at the start of stream. By default, no
1222 assumption is made about the first frame's expected pts, so no padding or
1223 trimming is done. For example, this could be set to 0 to pad the beginning with
1224 silence if an audio stream starts after the video stream or to trim any samples
1225 with a negative pts due to encoder delay.
1229 @section channelsplit
1230 Split each channel in input audio stream into a separate output stream.
1232 This filter accepts the following named parameters:
1234 @item channel_layout
1235 Channel layout of the input stream. Default is "stereo".
1238 For example, assuming a stereo input MP3 file
1240 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1242 will create an output Matroska file with two audio streams, one containing only
1243 the left channel and the other the right channel.
1245 To split a 5.1 WAV file into per-channel files
1247 ffmpeg -i in.wav -filter_complex
1248 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1249 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1250 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1255 Remap input channels to new locations.
1257 This filter accepts the following named parameters:
1259 @item channel_layout
1260 Channel layout of the output stream.
1263 Map channels from input to output. The argument is a '|'-separated list of
1264 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1265 @var{in_channel} form. @var{in_channel} can be either the name of the input
1266 channel (e.g. FL for front left) or its index in the input channel layout.
1267 @var{out_channel} is the name of the output channel or its index in the output
1268 channel layout. If @var{out_channel} is not given then it is implicitly an
1269 index, starting with zero and increasing by one for each mapping.
1272 If no mapping is present, the filter will implicitly map input channels to
1273 output channels preserving index.
1275 For example, assuming a 5.1+downmix input MOV file
1277 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1279 will create an output WAV file tagged as stereo from the downmix channels of
1282 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1284 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1288 Join multiple input streams into one multi-channel stream.
1290 The filter accepts the following named parameters:
1294 Number of input streams. Defaults to 2.
1296 @item channel_layout
1297 Desired output channel layout. Defaults to stereo.
1300 Map channels from inputs to output. The argument is a '|'-separated list of
1301 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1302 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1303 can be either the name of the input channel (e.g. FL for front left) or its
1304 index in the specified input stream. @var{out_channel} is the name of the output
1308 The filter will attempt to guess the mappings when those are not specified
1309 explicitly. It does so by first trying to find an unused matching input channel
1310 and if that fails it picks the first unused input channel.
1312 E.g. to join 3 inputs (with properly set channel layouts)
1314 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1317 To build a 5.1 output from 6 single-channel streams:
1319 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1320 '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'
1325 Convert the audio sample format, sample rate and channel layout. This filter is
1326 not meant to be used directly.
1330 Adjust the input audio volume.
1332 The filter accepts the following named parameters. If the key of the
1333 first options is omitted, the arguments are interpreted according to
1334 the following syntax:
1336 volume=@var{volume}:@var{precision}
1342 Expresses how the audio volume will be increased or decreased.
1344 Output values are clipped to the maximum value.
1346 The output audio volume is given by the relation:
1348 @var{output_volume} = @var{volume} * @var{input_volume}
1351 Default value for @var{volume} is 1.0.
1354 Set the mathematical precision.
1356 This determines which input sample formats will be allowed, which affects the
1357 precision of the volume scaling.
1361 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1363 32-bit floating-point; limits input sample format to FLT. (default)
1365 64-bit floating-point; limits input sample format to DBL.
1369 @subsection Examples
1373 Halve the input audio volume:
1377 volume=volume=-6.0206dB
1380 In all the above example the named key for @option{volume} can be
1381 omitted, for example like in:
1387 Increase input audio power by 6 decibels using fixed-point precision:
1389 volume=volume=6dB:precision=fixed
1393 @section volumedetect
1395 Detect the volume of the input video.
1397 The filter has no parameters. The input is not modified. Statistics about
1398 the volume will be printed in the log when the input stream end is reached.
1400 In particular it will show the mean volume (root mean square), maximum
1401 volume (on a per-sample basis), and the beginning of an histogram of the
1402 registered volume values (from the maximum value to a cumulated 1/1000 of
1405 All volumes are in decibels relative to the maximum PCM value.
1407 @subsection Examples
1409 Here is an excerpt of the output:
1411 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1412 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1413 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1414 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1415 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1416 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1417 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1418 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1419 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1425 The mean square energy is approximately -27 dB, or 10^-2.7.
1427 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1429 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1432 In other words, raising the volume by +4 dB does not cause any clipping,
1433 raising it by +5 dB causes clipping for 6 samples, etc.
1435 @c man end AUDIO FILTERS
1437 @chapter Audio Sources
1438 @c man begin AUDIO SOURCES
1440 Below is a description of the currently available audio sources.
1444 Buffer audio frames, and make them available to the filter chain.
1446 This source is mainly intended for a programmatic use, in particular
1447 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1449 It accepts the following named parameters:
1454 Timebase which will be used for timestamps of submitted frames. It must be
1455 either a floating-point number or in @var{numerator}/@var{denominator} form.
1458 The sample rate of the incoming audio buffers.
1461 The sample format of the incoming audio buffers.
1462 Either a sample format name or its corresponging integer representation from
1463 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1465 @item channel_layout
1466 The channel layout of the incoming audio buffers.
1467 Either a channel layout name from channel_layout_map in
1468 @file{libavutil/channel_layout.c} or its corresponding integer representation
1469 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1472 The number of channels of the incoming audio buffers.
1473 If both @var{channels} and @var{channel_layout} are specified, then they
1478 @subsection Examples
1481 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1484 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1485 Since the sample format with name "s16p" corresponds to the number
1486 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1489 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1494 Generate an audio signal specified by an expression.
1496 This source accepts in input one or more expressions (one for each
1497 channel), which are evaluated and used to generate a corresponding
1500 It accepts the syntax: @var{exprs}[::@var{options}].
1501 @var{exprs} is a list of expressions separated by ":", one for each
1502 separate channel. In case the @var{channel_layout} is not
1503 specified, the selected channel layout depends on the number of
1504 provided expressions.
1506 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1509 The description of the accepted options follows.
1513 @item channel_layout, c
1514 Set the channel layout. The number of channels in the specified layout
1515 must be equal to the number of specified expressions.
1518 Set the minimum duration of the sourced audio. See the function
1519 @code{av_parse_time()} for the accepted format.
1520 Note that the resulting duration may be greater than the specified
1521 duration, as the generated audio is always cut at the end of a
1524 If not specified, or the expressed duration is negative, the audio is
1525 supposed to be generated forever.
1528 Set the number of samples per channel per each output frame,
1531 @item sample_rate, s
1532 Specify the sample rate, default to 44100.
1535 Each expression in @var{exprs} can contain the following constants:
1539 number of the evaluated sample, starting from 0
1542 time of the evaluated sample expressed in seconds, starting from 0
1549 @subsection Examples
1559 Generate a sin signal with frequency of 440 Hz, set sample rate to
1562 aevalsrc="sin(440*2*PI*t)::s=8000"
1566 Generate a two channels signal, specify the channel layout (Front
1567 Center + Back Center) explicitly:
1569 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1573 Generate white noise:
1575 aevalsrc="-2+random(0)"
1579 Generate an amplitude modulated signal:
1581 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1585 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1587 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1594 Null audio source, return unprocessed audio frames. It is mainly useful
1595 as a template and to be employed in analysis / debugging tools, or as
1596 the source for filters which ignore the input data (for example the sox
1599 This source accepts the following options:
1603 @item channel_layout, cl
1605 Specify the channel layout, and can be either an integer or a string
1606 representing a channel layout. The default value of @var{channel_layout}
1609 Check the channel_layout_map definition in
1610 @file{libavutil/channel_layout.c} for the mapping between strings and
1611 channel layout values.
1613 @item sample_rate, r
1614 Specify the sample rate, and defaults to 44100.
1617 Set the number of samples per requested frames.
1621 @subsection Examples
1625 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1627 anullsrc=r=48000:cl=4
1631 Do the same operation with a more obvious syntax:
1633 anullsrc=r=48000:cl=mono
1638 Buffer audio frames, and make them available to the filter chain.
1640 This source is not intended to be part of user-supplied graph descriptions but
1641 for insertion by calling programs through the interface defined in
1642 @file{libavfilter/buffersrc.h}.
1644 It accepts the following named parameters:
1648 Timebase which will be used for timestamps of submitted frames. It must be
1649 either a floating-point number or in @var{numerator}/@var{denominator} form.
1655 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1657 @item channel_layout
1658 Channel layout of the audio data, in the form that can be accepted by
1659 @code{av_get_channel_layout()}.
1662 All the parameters need to be explicitly defined.
1666 Synthesize a voice utterance using the libflite library.
1668 To enable compilation of this filter you need to configure FFmpeg with
1669 @code{--enable-libflite}.
1671 Note that the flite library is not thread-safe.
1673 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1676 The description of the accepted parameters follows.
1681 If set to 1, list the names of the available voices and exit
1682 immediately. Default value is 0.
1685 Set the maximum number of samples per frame. Default value is 512.
1688 Set the filename containing the text to speak.
1691 Set the text to speak.
1694 Set the voice to use for the speech synthesis. Default value is
1695 @code{kal}. See also the @var{list_voices} option.
1698 @subsection Examples
1702 Read from file @file{speech.txt}, and synthetize the text using the
1703 standard flite voice:
1705 flite=textfile=speech.txt
1709 Read the specified text selecting the @code{slt} voice:
1711 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1715 Input text to ffmpeg:
1717 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1721 Make @file{ffplay} speak the specified text, using @code{flite} and
1722 the @code{lavfi} device:
1724 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1728 For more information about libflite, check:
1729 @url{http://www.speech.cs.cmu.edu/flite/}
1733 Generate an audio signal made of a sine wave with amplitude 1/8.
1735 The audio signal is bit-exact.
1737 The filter accepts the following options:
1742 Set the carrier frequency. Default is 440 Hz.
1744 @item beep_factor, b
1745 Enable a periodic beep every second with frequency @var{beep_factor} times
1746 the carrier frequency. Default is 0, meaning the beep is disabled.
1748 @item sample_rate, s
1749 Specify the sample rate, default is 44100.
1752 Specify the duration of the generated audio stream.
1754 @item samples_per_frame
1755 Set the number of samples per output frame, default is 1024.
1758 @subsection Examples
1763 Generate a simple 440 Hz sine wave:
1769 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1773 sine=frequency=220:beep_factor=4:duration=5
1778 @c man end AUDIO SOURCES
1780 @chapter Audio Sinks
1781 @c man begin AUDIO SINKS
1783 Below is a description of the currently available audio sinks.
1785 @section abuffersink
1787 Buffer audio frames, and make them available to the end of filter chain.
1789 This sink is mainly intended for programmatic use, in particular
1790 through the interface defined in @file{libavfilter/buffersink.h}.
1792 It requires a pointer to an AVABufferSinkContext structure, which
1793 defines the incoming buffers' formats, to be passed as the opaque
1794 parameter to @code{avfilter_init_filter} for initialization.
1798 Null audio sink, do absolutely nothing with the input audio. It is
1799 mainly useful as a template and to be employed in analysis / debugging
1802 @section abuffersink
1803 This sink is intended for programmatic use. Frames that arrive on this sink can
1804 be retrieved by the calling program using the interface defined in
1805 @file{libavfilter/buffersink.h}.
1807 This filter accepts no parameters.
1809 @c man end AUDIO SINKS
1811 @chapter Video Filters
1812 @c man begin VIDEO FILTERS
1814 When you configure your FFmpeg build, you can disable any of the
1815 existing filters using @code{--disable-filters}.
1816 The configure output will show the video filters included in your
1819 Below is a description of the currently available video filters.
1821 @section alphaextract
1823 Extract the alpha component from the input as a grayscale video. This
1824 is especially useful with the @var{alphamerge} filter.
1828 Add or replace the alpha component of the primary input with the
1829 grayscale value of a second input. This is intended for use with
1830 @var{alphaextract} to allow the transmission or storage of frame
1831 sequences that have alpha in a format that doesn't support an alpha
1834 For example, to reconstruct full frames from a normal YUV-encoded video
1835 and a separate video created with @var{alphaextract}, you might use:
1837 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1840 Since this filter is designed for reconstruction, it operates on frame
1841 sequences without considering timestamps, and terminates when either
1842 input reaches end of stream. This will cause problems if your encoding
1843 pipeline drops frames. If you're trying to apply an image as an
1844 overlay to a video stream, consider the @var{overlay} filter instead.
1848 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1849 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1850 Substation Alpha) subtitles files.
1854 Compute the bounding box for the non-black pixels in the input frame
1857 This filter computes the bounding box containing all the pixels with a
1858 luminance value greater than the minimum allowed value.
1859 The parameters describing the bounding box are printed on the filter
1862 @section blackdetect
1864 Detect video intervals that are (almost) completely black. Can be
1865 useful to detect chapter transitions, commercials, or invalid
1866 recordings. Output lines contains the time for the start, end and
1867 duration of the detected black interval expressed in seconds.
1869 In order to display the output lines, you need to set the loglevel at
1870 least to the AV_LOG_INFO value.
1872 The filter accepts the following options:
1875 @item black_min_duration, d
1876 Set the minimum detected black duration expressed in seconds. It must
1877 be a non-negative floating point number.
1879 Default value is 2.0.
1881 @item picture_black_ratio_th, pic_th
1882 Set the threshold for considering a picture "black".
1883 Express the minimum value for the ratio:
1885 @var{nb_black_pixels} / @var{nb_pixels}
1888 for which a picture is considered black.
1889 Default value is 0.98.
1891 @item pixel_black_th, pix_th
1892 Set the threshold for considering a pixel "black".
1894 The threshold expresses the maximum pixel luminance value for which a
1895 pixel is considered "black". The provided value is scaled according to
1896 the following equation:
1898 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1901 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1902 the input video format, the range is [0-255] for YUV full-range
1903 formats and [16-235] for YUV non full-range formats.
1905 Default value is 0.10.
1908 The following example sets the maximum pixel threshold to the minimum
1909 value, and detects only black intervals of 2 or more seconds:
1911 blackdetect=d=2:pix_th=0.00
1916 Detect frames that are (almost) completely black. Can be useful to
1917 detect chapter transitions or commercials. Output lines consist of
1918 the frame number of the detected frame, the percentage of blackness,
1919 the position in the file if known or -1 and the timestamp in seconds.
1921 In order to display the output lines, you need to set the loglevel at
1922 least to the AV_LOG_INFO value.
1924 The filter accepts parameters as a list of @var{key}=@var{value}
1925 pairs, separated by ":". If the key of the first options is omitted,
1926 the arguments are interpreted according to the syntax
1927 blackframe[=@var{amount}[:@var{threshold}]].
1929 The filter accepts the following options:
1934 The percentage of the pixels that have to be below the threshold, defaults to
1938 Threshold below which a pixel value is considered black, defaults to 32.
1944 Blend two video frames into each other.
1946 It takes two input streams and outputs one stream, the first input is the
1947 "top" layer and second input is "bottom" layer.
1948 Output terminates when shortest input terminates.
1950 A description of the accepted options follows.
1958 Set blend mode for specific pixel component or all pixel components in case
1959 of @var{all_mode}. Default value is @code{normal}.
1961 Available values for component modes are:
1994 Set blend opacity for specific pixel component or all pixel components in case
1995 of @var{all_opacity}. Only used in combination with pixel component blend modes.
2002 Set blend expression for specific pixel component or all pixel components in case
2003 of @var{all_expr}. Note that related mode options will be ignored if those are set.
2005 The expressions can use the following variables:
2009 The sequential number of the filtered frame, starting from @code{0}.
2013 the coordinates of the current sample
2017 the width and height of currently filtered plane
2021 Width and height scale depending on the currently filtered plane. It is the
2022 ratio between the corresponding luma plane number of pixels and the current
2023 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2024 @code{0.5,0.5} for chroma planes.
2027 Time of the current frame, expressed in seconds.
2030 Value of pixel component at current location for first video frame (top layer).
2033 Value of pixel component at current location for second video frame (bottom layer).
2037 @subsection Examples
2041 Apply transition from bottom layer to top layer in first 10 seconds:
2043 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2047 Apply 1x1 checkerboard effect:
2049 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2055 Apply boxblur algorithm to the input video.
2057 The filter accepts parameters as a list of @var{key}=@var{value}
2058 pairs, separated by ":". If the key of the first options is omitted,
2059 the arguments are interpreted according to the syntax
2060 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2062 This filter accepts the following options:
2075 A description of the accepted options follows.
2078 @item luma_radius, lr
2079 @item chroma_radius, cr
2080 @item alpha_radius, ar
2081 Set an expression for the box radius in pixels used for blurring the
2082 corresponding input plane.
2084 The radius value must be a non-negative number, and must not be
2085 greater than the value of the expression @code{min(w,h)/2} for the
2086 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2089 Default value for @option{luma_radius} is "2". If not specified,
2090 @option{chroma_radius} and @option{alpha_radius} default to the
2091 corresponding value set for @option{luma_radius}.
2093 The expressions can contain the following constants:
2096 the input width and height in pixels
2099 the input chroma image width and height in pixels
2102 horizontal and vertical chroma subsample values. For example for the
2103 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2106 @item luma_power, lp
2107 @item chroma_power, cp
2108 @item alpha_power, ap
2109 Specify how many times the boxblur filter is applied to the
2110 corresponding plane.
2112 Default value for @option{luma_power} is 2. If not specified,
2113 @option{chroma_power} and @option{alpha_power} default to the
2114 corresponding value set for @option{luma_power}.
2116 A value of 0 will disable the effect.
2119 @subsection Examples
2123 Apply a boxblur filter with luma, chroma, and alpha radius
2126 boxblur=luma_radius=2:luma_power=1
2131 Set luma radius to 2, alpha and chroma radius to 0:
2133 boxblur=2:1:cr=0:ar=0
2137 Set luma and chroma radius to a fraction of the video dimension:
2139 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2143 @section colormatrix
2145 Convert color matrix.
2147 The filter accepts the following options:
2152 Specify the source and destination color matrix. Both values must be
2155 The accepted values are:
2171 For example to convert from BT.601 to SMPTE-240M, use the command:
2173 colormatrix=bt601:smpte240m
2178 Copy the input source unchanged to the output. Mainly useful for
2183 Crop the input video to given dimensions.
2185 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2186 separated by ':'. If the key of the first options is omitted, the
2187 arguments are interpreted according to the syntax
2188 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2190 A description of the accepted options follows:
2193 Width of the output video. It defaults to @code{iw}.
2194 This expression is evaluated only once during the filter
2198 Height of the output video. It defaults to @code{ih}.
2199 This expression is evaluated only once during the filter
2203 Horizontal position, in the input video, of the left edge of the output video.
2204 It defaults to @code{(in_w-out_w)/2}.
2205 This expression is evaluated per-frame.
2208 Vertical position, in the input video, of the top edge of the output video.
2209 It defaults to @code{(in_h-out_h)/2}.
2210 This expression is evaluated per-frame.
2213 If set to 1 will force the output display aspect ratio
2214 to be the same of the input, by changing the output sample aspect
2215 ratio. It defaults to 0.
2218 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2219 expressions containing the following constants:
2223 the computed values for @var{x} and @var{y}. They are evaluated for
2227 the input width and height
2230 same as @var{in_w} and @var{in_h}
2233 the output (cropped) width and height
2236 same as @var{out_w} and @var{out_h}
2239 same as @var{iw} / @var{ih}
2242 input sample aspect ratio
2245 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2248 horizontal and vertical chroma subsample values. For example for the
2249 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2252 the number of input frame, starting from 0
2255 timestamp expressed in seconds, NAN if the input timestamp is unknown
2259 The expression for @var{out_w} may depend on the value of @var{out_h},
2260 and the expression for @var{out_h} may depend on @var{out_w}, but they
2261 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2262 evaluated after @var{out_w} and @var{out_h}.
2264 The @var{x} and @var{y} parameters specify the expressions for the
2265 position of the top-left corner of the output (non-cropped) area. They
2266 are evaluated for each frame. If the evaluated value is not valid, it
2267 is approximated to the nearest valid value.
2269 The expression for @var{x} may depend on @var{y}, and the expression
2270 for @var{y} may depend on @var{x}.
2272 @subsection Examples
2276 Crop area with size 100x100 at position (12,34).
2281 Using named options, the example above becomes:
2283 crop=w=100:h=100:x=12:y=34
2287 Crop the central input area with size 100x100:
2293 Crop the central input area with size 2/3 of the input video:
2295 crop=2/3*in_w:2/3*in_h
2299 Crop the input video central square:
2306 Delimit the rectangle with the top-left corner placed at position
2307 100:100 and the right-bottom corner corresponding to the right-bottom
2308 corner of the input image:
2310 crop=in_w-100:in_h-100:100:100
2314 Crop 10 pixels from the left and right borders, and 20 pixels from
2315 the top and bottom borders
2317 crop=in_w-2*10:in_h-2*20
2321 Keep only the bottom right quarter of the input image:
2323 crop=in_w/2:in_h/2:in_w/2:in_h/2
2327 Crop height for getting Greek harmony:
2329 crop=in_w:1/PHI*in_w
2333 Appply trembling effect:
2335 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)
2339 Apply erratic camera effect depending on timestamp:
2341 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)"
2345 Set x depending on the value of y:
2347 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2353 Auto-detect crop size.
2355 Calculate necessary cropping parameters and prints the recommended
2356 parameters through the logging system. The detected dimensions
2357 correspond to the non-black area of the input video.
2359 The filter accepts parameters as a list of @var{key}=@var{value}
2360 pairs, separated by ":". If the key of the first options is omitted,
2361 the arguments are interpreted according to the syntax
2362 [@option{limit}[:@option{round}[:@option{reset}]]].
2364 A description of the accepted options follows.
2369 Set higher black value threshold, which can be optionally specified
2370 from nothing (0) to everything (255). An intensity value greater
2371 to the set value is considered non-black. Default value is 24.
2374 Set the value for which the width/height should be divisible by. The
2375 offset is automatically adjusted to center the video. Use 2 to get
2376 only even dimensions (needed for 4:2:2 video). 16 is best when
2377 encoding to most video codecs. Default value is 16.
2380 Set the counter that determines after how many frames cropdetect will
2381 reset the previously detected largest video area and start over to
2382 detect the current optimal crop area. Default value is 0.
2384 This can be useful when channel logos distort the video area. 0
2385 indicates never reset and return the largest area encountered during
2391 Apply color adjustments using curves.
2393 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2394 component (red, green and blue) has its values defined by @var{N} key points
2395 tied from each other using a smooth curve. The x-axis represents the pixel
2396 values from the input frame, and the y-axis the new pixel values to be set for
2399 By default, a component curve is defined by the two points @var{(0;0)} and
2400 @var{(1;1)}. This creates a straight line where each original pixel value is
2401 "adjusted" to its own value, which means no change to the image.
2403 The filter allows you to redefine these two points and add some more. A new
2404 curve (using a natural cubic spline interpolation) will be define to pass
2405 smoothly through all these new coordinates. The new defined points needs to be
2406 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2407 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2408 the vector spaces, the values will be clipped accordingly.
2410 If there is no key point defined in @code{x=0}, the filter will automatically
2411 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2412 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2414 The filter accepts the following options:
2418 Select one of the available color presets. This option can be used in addition
2419 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2420 options takes priority on the preset values.
2421 Available presets are:
2424 @item color_negative
2427 @item increase_contrast
2429 @item linear_contrast
2430 @item medium_contrast
2432 @item strong_contrast
2435 Default is @code{none}.
2437 Set the key points for the red component.
2439 Set the key points for the green component.
2441 Set the key points for the blue component.
2443 Set the key points for all components.
2444 Can be used in addition to the other key points component
2445 options. In this case, the unset component(s) will fallback on this
2446 @option{all} setting.
2449 To avoid some filtergraph syntax conflicts, each key points list need to be
2450 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2452 @subsection Examples
2456 Increase slightly the middle level of blue:
2458 curves=blue='0.5/0.58'
2464 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2466 Here we obtain the following coordinates for each components:
2469 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2471 @code{(0;0) (0.50;0.48) (1;1)}
2473 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2477 The previous example can also be achieved with the associated built-in preset:
2479 curves=preset=vintage
2491 Drop frames that do not differ greatly from the previous frame in
2492 order to reduce frame rate.
2494 The main use of this filter is for very-low-bitrate encoding
2495 (e.g. streaming over dialup modem), but it could in theory be used for
2496 fixing movies that were inverse-telecined incorrectly.
2498 A description of the accepted options follows.
2502 Set the maximum number of consecutive frames which can be dropped (if
2503 positive), or the minimum interval between dropped frames (if
2504 negative). If the value is 0, the frame is dropped unregarding the
2505 number of previous sequentially dropped frames.
2512 Set the dropping threshold values.
2514 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2515 represent actual pixel value differences, so a threshold of 64
2516 corresponds to 1 unit of difference for each pixel, or the same spread
2517 out differently over the block.
2519 A frame is a candidate for dropping if no 8x8 blocks differ by more
2520 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2521 meaning the whole image) differ by more than a threshold of @option{lo}.
2523 Default value for @option{hi} is 64*12, default value for @option{lo} is
2524 64*5, and default value for @option{frac} is 0.33.
2529 Suppress a TV station logo by a simple interpolation of the surrounding
2530 pixels. Just set a rectangle covering the logo and watch it disappear
2531 (and sometimes something even uglier appear - your mileage may vary).
2533 This filter accepts the following options:
2537 Specify the top left corner coordinates of the logo. They must be
2541 Specify the width and height of the logo to clear. They must be
2545 Specify the thickness of the fuzzy edge of the rectangle (added to
2546 @var{w} and @var{h}). The default value is 4.
2549 When set to 1, a green rectangle is drawn on the screen to simplify
2550 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2551 @var{band} is set to 4. The default value is 0.
2555 @subsection Examples
2559 Set a rectangle covering the area with top left corner coordinates 0,0
2560 and size 100x77, setting a band of size 10:
2562 delogo=x=0:y=0:w=100:h=77:band=10
2569 Attempt to fix small changes in horizontal and/or vertical shift. This
2570 filter helps remove camera shake from hand-holding a camera, bumping a
2571 tripod, moving on a vehicle, etc.
2573 The filter accepts the following options:
2581 Specify a rectangular area where to limit the search for motion
2583 If desired the search for motion vectors can be limited to a
2584 rectangular area of the frame defined by its top left corner, width
2585 and height. These parameters have the same meaning as the drawbox
2586 filter which can be used to visualise the position of the bounding
2589 This is useful when simultaneous movement of subjects within the frame
2590 might be confused for camera motion by the motion vector search.
2592 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2593 then the full frame is used. This allows later options to be set
2594 without specifying the bounding box for the motion vector search.
2596 Default - search the whole frame.
2600 Specify the maximum extent of movement in x and y directions in the
2601 range 0-64 pixels. Default 16.
2604 Specify how to generate pixels to fill blanks at the edge of the
2605 frame. Available values are:
2608 Fill zeroes at blank locations
2610 Original image at blank locations
2612 Extruded edge value at blank locations
2614 Mirrored edge at blank locations
2616 Default value is @samp{mirror}.
2619 Specify the blocksize to use for motion search. Range 4-128 pixels,
2623 Specify the contrast threshold for blocks. Only blocks with more than
2624 the specified contrast (difference between darkest and lightest
2625 pixels) will be considered. Range 1-255, default 125.
2628 Specify the search strategy. Available values are:
2631 Set exhaustive search
2633 Set less exhaustive search.
2635 Default value is @samp{exhaustive}.
2638 If set then a detailed log of the motion search is written to the
2642 If set to 1, specify using OpenCL capabilities, only available if
2643 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2649 Draw a colored box on the input image.
2651 This filter accepts the following options:
2655 Specify the top left corner coordinates of the box. Default to 0.
2659 Specify the width and height of the box, if 0 they are interpreted as
2660 the input width and height. Default to 0.
2663 Specify the color of the box to write, it can be the name of a color
2664 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2665 value @code{invert} is used, the box edge color is the same as the
2666 video with inverted luma.
2669 Set the thickness of the box edge. Default value is @code{4}.
2672 @subsection Examples
2676 Draw a black box around the edge of the input image:
2682 Draw a box with color red and an opacity of 50%:
2684 drawbox=10:20:200:60:red@@0.5
2687 The previous example can be specified as:
2689 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2693 Fill the box with pink color:
2695 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2702 Draw text string or text from specified file on top of video using the
2703 libfreetype library.
2705 To enable compilation of this filter you need to configure FFmpeg with
2706 @code{--enable-libfreetype}.
2710 The description of the accepted parameters follows.
2715 Used to draw a box around text using background color.
2716 Value should be either 1 (enable) or 0 (disable).
2717 The default value of @var{box} is 0.
2720 The color to be used for drawing box around text.
2721 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2722 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2723 The default value of @var{boxcolor} is "white".
2726 Set an expression which specifies if the text should be drawn. If the
2727 expression evaluates to 0, the text is not drawn. This is useful for
2728 specifying that the text should be drawn only when specific conditions
2731 Default value is "1".
2733 See below for the list of accepted constants and functions.
2736 Select how the @var{text} is expanded. Can be either @code{none},
2737 @code{strftime} (deprecated) or
2738 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2742 If true, check and fix text coords to avoid clipping.
2745 The color to be used for drawing fonts.
2746 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2747 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2748 The default value of @var{fontcolor} is "black".
2751 The font file to be used for drawing text. Path must be included.
2752 This parameter is mandatory.
2755 The font size to be used for drawing text.
2756 The default value of @var{fontsize} is 16.
2759 Flags to be used for loading the fonts.
2761 The flags map the corresponding flags supported by libfreetype, and are
2762 a combination of the following values:
2769 @item vertical_layout
2770 @item force_autohint
2773 @item ignore_global_advance_width
2775 @item ignore_transform
2782 Default value is "render".
2784 For more information consult the documentation for the FT_LOAD_*
2788 The color to be used for drawing a shadow behind the drawn text. It
2789 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2790 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2791 The default value of @var{shadowcolor} is "black".
2793 @item shadowx, shadowy
2794 The x and y offsets for the text shadow position with respect to the
2795 position of the text. They can be either positive or negative
2796 values. Default value for both is "0".
2799 The size in number of spaces to use for rendering the tab.
2803 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2804 format. It can be used with or without text parameter. @var{timecode_rate}
2805 option must be specified.
2807 @item timecode_rate, rate, r
2808 Set the timecode frame rate (timecode only).
2811 The text string to be drawn. The text must be a sequence of UTF-8
2813 This parameter is mandatory if no file is specified with the parameter
2817 A text file containing text to be drawn. The text must be a sequence
2818 of UTF-8 encoded characters.
2820 This parameter is mandatory if no text string is specified with the
2821 parameter @var{text}.
2823 If both @var{text} and @var{textfile} are specified, an error is thrown.
2826 If set to 1, the @var{textfile} will be reloaded before each frame.
2827 Be sure to update it atomically, or it may be read partially, or even fail.
2830 The expressions which specify the offsets where text will be drawn
2831 within the video frame. They are relative to the top/left border of the
2834 The default value of @var{x} and @var{y} is "0".
2836 See below for the list of accepted constants and functions.
2839 The parameters for @var{x} and @var{y} are expressions containing the
2840 following constants and functions:
2844 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2847 horizontal and vertical chroma subsample values. For example for the
2848 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2851 the height of each text line
2859 @item max_glyph_a, ascent
2860 the maximum distance from the baseline to the highest/upper grid
2861 coordinate used to place a glyph outline point, for all the rendered
2863 It is a positive value, due to the grid's orientation with the Y axis
2866 @item max_glyph_d, descent
2867 the maximum distance from the baseline to the lowest grid coordinate
2868 used to place a glyph outline point, for all the rendered glyphs.
2869 This is a negative value, due to the grid's orientation, with the Y axis
2873 maximum glyph height, that is the maximum height for all the glyphs
2874 contained in the rendered text, it is equivalent to @var{ascent} -
2878 maximum glyph width, that is the maximum width for all the glyphs
2879 contained in the rendered text
2882 the number of input frame, starting from 0
2884 @item rand(min, max)
2885 return a random number included between @var{min} and @var{max}
2888 input sample aspect ratio
2891 timestamp expressed in seconds, NAN if the input timestamp is unknown
2894 the height of the rendered text
2897 the width of the rendered text
2900 the x and y offset coordinates where the text is drawn.
2902 These parameters allow the @var{x} and @var{y} expressions to refer
2903 each other, so you can for example specify @code{y=x/dar}.
2906 If libavfilter was built with @code{--enable-fontconfig}, then
2907 @option{fontfile} can be a fontconfig pattern or omitted.
2909 @anchor{drawtext_expansion}
2910 @subsection Text expansion
2912 If @option{expansion} is set to @code{strftime},
2913 the filter recognizes strftime() sequences in the provided text and
2914 expands them accordingly. Check the documentation of strftime(). This
2915 feature is deprecated.
2917 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2919 If @option{expansion} is set to @code{normal} (which is the default),
2920 the following expansion mechanism is used.
2922 The backslash character '\', followed by any character, always expands to
2923 the second character.
2925 Sequence of the form @code{%@{...@}} are expanded. The text between the
2926 braces is a function name, possibly followed by arguments separated by ':'.
2927 If the arguments contain special characters or delimiters (':' or '@}'),
2928 they should be escaped.
2930 Note that they probably must also be escaped as the value for the
2931 @option{text} option in the filter argument string and as the filter
2932 argument in the filtergraph description, and possibly also for the shell,
2933 that makes up to four levels of escaping; using a text file avoids these
2936 The following functions are available:
2941 The expression evaluation result.
2943 It must take one argument specifying the expression to be evaluated,
2944 which accepts the same constants and functions as the @var{x} and
2945 @var{y} values. Note that not all constants should be used, for
2946 example the text size is not known when evaluating the expression, so
2947 the constants @var{text_w} and @var{text_h} will have an undefined
2951 The time at which the filter is running, expressed in UTC.
2952 It can accept an argument: a strftime() format string.
2955 The time at which the filter is running, expressed in the local time zone.
2956 It can accept an argument: a strftime() format string.
2959 The frame number, starting from 0.
2962 The timestamp of the current frame, in seconds, with microsecond accuracy.
2966 @subsection Examples
2970 Draw "Test Text" with font FreeSerif, using the default values for the
2971 optional parameters.
2974 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2978 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2979 and y=50 (counting from the top-left corner of the screen), text is
2980 yellow with a red box around it. Both the text and the box have an
2984 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2985 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2988 Note that the double quotes are not necessary if spaces are not used
2989 within the parameter list.
2992 Show the text at the center of the video frame:
2994 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2998 Show a text line sliding from right to left in the last row of the video
2999 frame. The file @file{LONG_LINE} is assumed to contain a single line
3002 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3006 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3008 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3012 Draw a single green letter "g", at the center of the input video.
3013 The glyph baseline is placed at half screen height.
3015 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3019 Show text for 1 second every 3 seconds:
3021 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3025 Use fontconfig to set the font. Note that the colons need to be escaped.
3027 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3031 Print the date of a real-time encoding (see strftime(3)):
3033 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3038 For more information about libfreetype, check:
3039 @url{http://www.freetype.org/}.
3041 For more information about fontconfig, check:
3042 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3046 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3048 The filter accepts the following options:
3052 Set low and high threshold values used by the Canny thresholding
3055 The high threshold selects the "strong" edge pixels, which are then
3056 connected through 8-connectivity with the "weak" edge pixels selected
3057 by the low threshold.
3059 @var{low} and @var{high} threshold values must be choosen in the range
3060 [0,1], and @var{low} should be lesser or equal to @var{high}.
3062 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3068 edgedetect=low=0.1:high=0.4
3073 Apply fade-in/out effect to input video.
3075 This filter accepts the following options:
3079 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3081 Default is @code{in}.
3083 @item start_frame, s
3084 Specify the number of the start frame for starting to apply the fade
3085 effect. Default is 0.
3088 The number of frames for which the fade effect has to last. At the end of the
3089 fade-in effect the output video will have the same intensity as the input video,
3090 at the end of the fade-out transition the output video will be completely black.
3094 If set to 1, fade only alpha channel, if one exists on the input.
3098 @subsection Examples
3102 Fade in first 30 frames of video:
3107 The command above is equivalent to:
3113 Fade out last 45 frames of a 200-frame video:
3116 fade=type=out:start_frame=155:nb_frames=45
3120 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3122 fade=in:0:25, fade=out:975:25
3126 Make first 5 frames black, then fade in from frame 5-24:
3132 Fade in alpha over first 25 frames of video:
3134 fade=in:0:25:alpha=1
3140 Extract a single field from an interlaced image using stride
3141 arithmetic to avoid wasting CPU time. The output frames are marked as
3144 The filter accepts the following options:
3148 Specify whether to extract the top (if the value is @code{0} or
3149 @code{top}) or the bottom field (if the value is @code{1} or
3155 Transform the field order of the input video.
3157 This filter accepts the following options:
3162 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3163 for bottom field first.
3166 Default value is @samp{tff}.
3168 Transformation is achieved by shifting the picture content up or down
3169 by one line, and filling the remaining line with appropriate picture content.
3170 This method is consistent with most broadcast field order converters.
3172 If the input video is not flagged as being interlaced, or it is already
3173 flagged as being of the required output field order then this filter does
3174 not alter the incoming video.
3176 This filter is very useful when converting to or from PAL DV material,
3177 which is bottom field first.
3181 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3186 Buffer input images and send them when they are requested.
3188 This filter is mainly useful when auto-inserted by the libavfilter
3191 The filter does not take parameters.
3196 Convert the input video to one of the specified pixel formats.
3197 Libavfilter will try to pick one that is supported for the input to
3200 This filter accepts the following parameters:
3204 A '|'-separated list of pixel format names, for example
3205 "pix_fmts=yuv420p|monow|rgb24".
3209 @subsection Examples
3213 Convert the input video to the format @var{yuv420p}
3215 format=pix_fmts=yuv420p
3218 Convert the input video to any of the formats in the list
3220 format=pix_fmts=yuv420p|yuv444p|yuv410p
3226 Convert the video to specified constant frame rate by duplicating or dropping
3227 frames as necessary.
3229 This filter accepts the following named parameters:
3233 Desired output frame rate. The default is @code{25}.
3238 Possible values are:
3241 zero round towards 0
3245 round towards -infinity
3247 round towards +infinity
3251 The default is @code{near}.
3255 Alternatively, the options can be specified as a flat string:
3256 @var{fps}[:@var{round}].
3258 See also the @ref{setpts} filter.
3262 Select one frame every N-th frame.
3264 This filter accepts the following option:
3267 Select frame after every @code{step} frames.
3268 Allowed values are positive integers higher than 0. Default value is @code{1}.
3274 Apply a frei0r effect to the input video.
3276 To enable compilation of this filter you need to install the frei0r
3277 header and configure FFmpeg with @code{--enable-frei0r}.
3279 This filter accepts the following options:
3284 The name to the frei0r effect to load. If the environment variable
3285 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3286 directories specified by the colon separated list in @env{FREIOR_PATH},
3287 otherwise in the standard frei0r paths, which are in this order:
3288 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3289 @file{/usr/lib/frei0r-1/}.
3292 A '|'-separated list of parameters to pass to the frei0r effect.
3296 A frei0r effect parameter can be a boolean (whose values are specified
3297 with "y" and "n"), a double, a color (specified by the syntax
3298 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3299 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3300 description), a position (specified by the syntax @var{X}/@var{Y},
3301 @var{X} and @var{Y} being float numbers) and a string.
3303 The number and kind of parameters depend on the loaded effect. If an
3304 effect parameter is not specified the default value is set.
3306 @subsection Examples
3310 Apply the distort0r effect, set the first two double parameters:
3312 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3316 Apply the colordistance effect, take a color as first parameter:
3318 frei0r=colordistance:0.2/0.3/0.4
3319 frei0r=colordistance:violet
3320 frei0r=colordistance:0x112233
3324 Apply the perspective effect, specify the top left and top right image
3327 frei0r=perspective:0.2/0.2|0.8/0.2
3331 For more information see:
3332 @url{http://frei0r.dyne.org}
3336 The filter accepts the following options:
3340 the luminance expression
3342 the chrominance blue expression
3344 the chrominance red expression
3346 the alpha expression
3349 If one of the chrominance expression is not defined, it falls back on the other
3350 one. If no alpha expression is specified it will evaluate to opaque value.
3351 If none of chrominance expressions are
3352 specified, they will evaluate the luminance expression.
3354 The expressions can use the following variables and functions:
3358 The sequential number of the filtered frame, starting from @code{0}.
3362 The coordinates of the current sample.
3366 The width and height of the image.
3370 Width and height scale depending on the currently filtered plane. It is the
3371 ratio between the corresponding luma plane number of pixels and the current
3372 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3373 @code{0.5,0.5} for chroma planes.
3376 Time of the current frame, expressed in seconds.
3379 Return the value of the pixel at location (@var{x},@var{y}) of the current
3383 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3387 Return the value of the pixel at location (@var{x},@var{y}) of the
3388 blue-difference chroma plane. Returns 0 if there is no such plane.
3391 Return the value of the pixel at location (@var{x},@var{y}) of the
3392 red-difference chroma plane. Returns 0 if there is no such plane.
3395 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3396 plane. Returns 0 if there is no such plane.
3399 For functions, if @var{x} and @var{y} are outside the area, the value will be
3400 automatically clipped to the closer edge.
3402 @subsection Examples
3406 Flip the image horizontally:
3412 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3413 wavelength of 100 pixels:
3415 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3419 Generate a fancy enigmatic moving light:
3421 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
3427 Fix the banding artifacts that are sometimes introduced into nearly flat
3428 regions by truncation to 8bit color depth.
3429 Interpolate the gradients that should go where the bands are, and
3432 This filter is designed for playback only. Do not use it prior to
3433 lossy compression, because compression tends to lose the dither and
3434 bring back the bands.
3436 This filter accepts the following options:
3441 The maximum amount by which the filter will change any one pixel. Also the
3442 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3443 64, default value is 1.2, out-of-range values will be clipped to the valid
3447 The neighborhood to fit the gradient to. A larger radius makes for smoother
3448 gradients, but also prevents the filter from modifying the pixels near detailed
3449 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3450 will be clipped to the valid range.
3454 Alternatively, the options can be specified as a flat string:
3455 @var{strength}[:@var{radius}]
3457 @subsection Examples
3461 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3467 Specify radius, omitting the strength (which will fall-back to the default
3477 Flip the input video horizontally.
3479 For example to horizontally flip the input video with @command{ffmpeg}:
3481 ffmpeg -i in.avi -vf "hflip" out.avi
3485 This filter applies a global color histogram equalization on a
3488 It can be used to correct video that has a compressed range of pixel
3489 intensities. The filter redistributes the pixel intensities to
3490 equalize their distribution across the intensity range. It may be
3491 viewed as an "automatically adjusting contrast filter". This filter is
3492 useful only for correcting degraded or poorly captured source
3495 The filter accepts the following options:
3499 Determine the amount of equalization to be applied. As the strength
3500 is reduced, the distribution of pixel intensities more-and-more
3501 approaches that of the input frame. The value must be a float number
3502 in the range [0,1] and defaults to 0.200.
3505 Set the maximum intensity that can generated and scale the output
3506 values appropriately. The strength should be set as desired and then
3507 the intensity can be limited if needed to avoid washing-out. The value
3508 must be a float number in the range [0,1] and defaults to 0.210.
3511 Set the antibanding level. If enabled the filter will randomly vary
3512 the luminance of output pixels by a small amount to avoid banding of
3513 the histogram. Possible values are @code{none}, @code{weak} or
3514 @code{strong}. It defaults to @code{none}.
3519 Compute and draw a color distribution histogram for the input video.
3521 The computed histogram is a representation of distribution of color components
3524 The filter accepts the following options:
3530 It accepts the following values:
3533 standard histogram that display color components distribution in an image.
3534 Displays color graph for each color component. Shows distribution
3535 of the Y, U, V, A or G, B, R components, depending on input format,
3536 in current frame. Bellow each graph is color component scale meter.
3539 chroma values in vectorscope, if brighter more such chroma values are
3540 distributed in an image.
3541 Displays chroma values (U/V color placement) in two dimensional graph
3542 (which is called a vectorscope). It can be used to read of the hue and
3543 saturation of the current frame. At a same time it is a histogram.
3544 The whiter a pixel in the vectorscope, the more pixels of the input frame
3545 correspond to that pixel (that is the more pixels have this chroma value).
3546 The V component is displayed on the horizontal (X) axis, with the leftmost
3547 side being V = 0 and the rightmost side being V = 255.
3548 The U component is displayed on the vertical (Y) axis, with the top
3549 representing U = 0 and the bottom representing U = 255.
3551 The position of a white pixel in the graph corresponds to the chroma value
3552 of a pixel of the input clip. So the graph can be used to read of the
3553 hue (color flavor) and the saturation (the dominance of the hue in the color).
3554 As the hue of a color changes, it moves around the square. At the center of
3555 the square, the saturation is zero, which means that the corresponding pixel
3556 has no color. If you increase the amount of a specific color, while leaving
3557 the other colors unchanged, the saturation increases, and you move towards
3558 the edge of the square.
3561 chroma values in vectorscope, similar as @code{color} but actual chroma values
3565 per row/column color component graph. In row mode graph in the left side represents
3566 color component value 0 and right side represents value = 255. In column mode top
3567 side represents color component value = 0 and bottom side represents value = 255.
3569 Default value is @code{levels}.
3572 Set height of level in @code{levels}. Default value is @code{200}.
3573 Allowed range is [50, 2048].
3576 Set height of color scale in @code{levels}. Default value is @code{12}.
3577 Allowed range is [0, 40].
3580 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3581 of same luminance values across input rows/columns are distributed.
3582 Default value is @code{10}. Allowed range is [1, 255].
3585 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3586 Default is @code{row}.
3589 Set display mode for @code{waveform} and @code{levels}.
3590 It accepts the following values:
3593 Display separate graph for the color components side by side in
3594 @code{row} waveform mode or one below other in @code{column} waveform mode
3595 for @code{waveform} histogram mode. For @code{levels} histogram mode
3596 per color component graphs are placed one bellow other.
3598 This display mode in @code{waveform} histogram mode makes it easy to spot
3599 color casts in the highlights and shadows of an image, by comparing the
3600 contours of the top and the bottom of each waveform.
3601 Since whites, grays, and blacks are characterized by
3602 exactly equal amounts of red, green, and blue, neutral areas of the
3603 picture should display three waveforms of roughly equal width/height.
3604 If not, the correction is easy to make by making adjustments to level the
3608 Presents information that's identical to that in the @code{parade}, except
3609 that the graphs representing color components are superimposed directly
3612 This display mode in @code{waveform} histogram mode can make it easier to spot
3613 the relative differences or similarities in overlapping areas of the color
3614 components that are supposed to be identical, such as neutral whites, grays,
3617 Default is @code{parade}.
3620 @subsection Examples
3625 Calculate and draw histogram:
3627 ffplay -i input -vf histogram
3634 High precision/quality 3d denoise filter. This filter aims to reduce
3635 image noise producing smooth images and making still images really
3636 still. It should enhance compressibility.
3638 It accepts the following optional parameters:
3642 a non-negative float number which specifies spatial luma strength,
3645 @item chroma_spatial
3646 a non-negative float number which specifies spatial chroma strength,
3647 defaults to 3.0*@var{luma_spatial}/4.0
3650 a float number which specifies luma temporal strength, defaults to
3651 6.0*@var{luma_spatial}/4.0
3654 a float number which specifies chroma temporal strength, defaults to
3655 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3660 Modify the hue and/or the saturation of the input.
3662 This filter accepts the following optional named options:
3666 Specify the hue angle as a number of degrees. It accepts a float
3667 number or an expression, and defaults to 0.0.
3670 Specify the hue angle as a number of radians. It accepts a float
3671 number or an expression, and defaults to 0.0.
3674 Specify the saturation in the [-10,10] range. It accepts a float number and
3678 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3679 following constants:
3683 frame count of the input frame starting from 0
3686 presentation timestamp of the input frame expressed in time base units
3689 frame rate of the input video, NAN if the input frame rate is unknown
3692 timestamp expressed in seconds, NAN if the input timestamp is unknown
3695 time base of the input video
3698 The options can also be set using the syntax: @var{hue}:@var{saturation}
3700 In this case @var{hue} is expressed in degrees.
3702 @subsection Examples
3706 Set the hue to 90 degrees and the saturation to 1.0:
3712 Same command but expressing the hue in radians:
3718 Same command without named options, hue must be expressed in degrees:
3724 Note that "h:s" syntax does not support expressions for the values of
3725 h and s, so the following example will issue an error:
3731 Rotate hue and make the saturation swing between 0
3732 and 2 over a period of 1 second:
3734 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3738 Apply a 3 seconds saturation fade-in effect starting at 0:
3743 The general fade-in expression can be written as:
3745 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3749 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3751 hue="s=max(0\, min(1\, (8-t)/3))"
3754 The general fade-out expression can be written as:
3756 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3761 @subsection Commands
3763 This filter supports the following command:
3766 Modify the hue and/or the saturation of the input video.
3767 The command accepts the same named options and syntax than when calling the
3768 filter from the command-line.
3770 If a parameter is omitted, it is kept at its current value.
3775 Detect video interlacing type.
3777 This filter tries to detect if the input is interlaced or progressive,
3778 top or bottom field first.
3780 The filter accepts the following options:
3784 Set interlacing threshold.
3786 Set progressive threshold.
3791 Deinterleave or interleave fields.
3793 This filter allows to process interlaced images fields without
3794 deinterlacing them. Deinterleaving splits the input frame into 2
3795 fields (so called half pictures). Odd lines are moved to the top
3796 half of the output image, even lines to the bottom half.
3797 You can process (filter) them independently and then re-interleave them.
3799 The filter accepts the following options:
3803 @item chroma_mode, s
3805 Available values for @var{luma_mode}, @var{chroma_mode} and
3806 @var{alpha_mode} are:
3812 @item deinterleave, d
3813 Deinterleave fields, placing one above the other.
3816 Interleave fields. Reverse the effect of deinterleaving.
3818 Default value is @code{none}.
3821 @item chroma_swap, cs
3822 @item alpha_swap, as
3823 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3828 Deinterlace input video by applying Donald Graft's adaptive kernel
3829 deinterling. Work on interlaced parts of a video to produce
3832 The description of the accepted parameters follows.
3836 Set the threshold which affects the filter's tolerance when
3837 determining if a pixel line must be processed. It must be an integer
3838 in the range [0,255] and defaults to 10. A value of 0 will result in
3839 applying the process on every pixels.
3842 Paint pixels exceeding the threshold value to white if set to 1.
3846 Set the fields order. Swap fields if set to 1, leave fields alone if
3850 Enable additional sharpening if set to 1. Default is 0.
3853 Enable twoway sharpening if set to 1. Default is 0.
3856 @subsection Examples
3860 Apply default values:
3862 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3866 Enable additional sharpening:
3872 Paint processed pixels in white:
3878 @section lut, lutrgb, lutyuv
3880 Compute a look-up table for binding each pixel component input value
3881 to an output value, and apply it to input video.
3883 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3884 to an RGB input video.
3886 These filters accept the following options:
3889 set first pixel component expression
3891 set second pixel component expression
3893 set third pixel component expression
3895 set fourth pixel component expression, corresponds to the alpha component
3898 set red component expression
3900 set green component expression
3902 set blue component expression
3904 alpha component expression
3907 set Y/luminance component expression
3909 set U/Cb component expression
3911 set V/Cr component expression
3914 Each of them specifies the expression to use for computing the lookup table for
3915 the corresponding pixel component values.
3917 The exact component associated to each of the @var{c*} options depends on the
3920 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3921 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3923 The expressions can contain the following constants and functions:
3927 the input width and height
3930 input value for the pixel component
3933 the input value clipped in the @var{minval}-@var{maxval} range
3936 maximum value for the pixel component
3939 minimum value for the pixel component
3942 the negated value for the pixel component value clipped in the
3943 @var{minval}-@var{maxval} range , it corresponds to the expression
3944 "maxval-clipval+minval"
3947 the computed value in @var{val} clipped in the
3948 @var{minval}-@var{maxval} range
3950 @item gammaval(gamma)
3951 the computed gamma correction value of the pixel component value
3952 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3954 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3958 All expressions default to "val".
3960 @subsection Examples
3966 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3967 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3970 The above is the same as:
3972 lutrgb="r=negval:g=negval:b=negval"
3973 lutyuv="y=negval:u=negval:v=negval"
3983 Remove chroma components, turns the video into a graytone image:
3985 lutyuv="u=128:v=128"
3989 Apply a luma burning effect:
3995 Remove green and blue components:
4001 Set a constant alpha channel value on input:
4003 format=rgba,lutrgb=a="maxval-minval/2"
4007 Correct luminance gamma by a 0.5 factor:
4009 lutyuv=y=gammaval(0.5)
4013 Discard least significant bits of luma:
4015 lutyuv=y='bitand(val, 128+64+32)'
4021 Apply an MPlayer filter to the input video.
4023 This filter provides a wrapper around most of the filters of
4026 This wrapper is considered experimental. Some of the wrapped filters
4027 may not work properly and we may drop support for them, as they will
4028 be implemented natively into FFmpeg. Thus you should avoid
4029 depending on them when writing portable scripts.
4031 The filters accepts the parameters:
4032 @var{filter_name}[:=]@var{filter_params}
4034 @var{filter_name} is the name of a supported MPlayer filter,
4035 @var{filter_params} is a string containing the parameters accepted by
4038 The list of the currently supported filters follows:
4065 The parameter syntax and behavior for the listed filters are the same
4066 of the corresponding MPlayer filters. For detailed instructions check
4067 the "VIDEO FILTERS" section in the MPlayer manual.
4069 @subsection Examples
4073 Adjust gamma, brightness, contrast:
4079 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4085 This filter accepts an integer in input, if non-zero it negates the
4086 alpha component (if available). The default value in input is 0.
4090 Force libavfilter not to use any of the specified pixel formats for the
4091 input to the next filter.
4093 This filter accepts the following parameters:
4097 A '|'-separated list of pixel format names, for example
4098 "pix_fmts=yuv420p|monow|rgb24".
4102 @subsection Examples
4106 Force libavfilter to use a format different from @var{yuv420p} for the
4107 input to the vflip filter:
4109 noformat=pix_fmts=yuv420p,vflip
4113 Convert the input video to any of the formats not contained in the list:
4115 noformat=yuv420p|yuv444p|yuv410p
4121 Add noise on video input frame.
4123 The filter accepts the following options:
4131 Set noise seed for specific pixel component or all pixel components in case
4132 of @var{all_seed}. Default value is @code{123457}.
4134 @item all_strength, alls
4135 @item c0_strength, c0s
4136 @item c1_strength, c1s
4137 @item c2_strength, c2s
4138 @item c3_strength, c3s
4139 Set noise strength for specific pixel component or all pixel components in case
4140 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4142 @item all_flags, allf
4147 Set pixel component flags or set flags for all components if @var{all_flags}.
4148 Available values for component flags are:
4151 averaged temporal noise (smoother)
4153 mix random noise with a (semi)regular pattern
4155 higher quality (slightly better looking, slightly slower)
4157 temporal noise (noise pattern changes between frames)
4159 uniform noise (gaussian otherwise)
4163 @subsection Examples
4165 Add temporal and uniform noise to input video:
4167 noise=alls=20:allf=t+u
4172 Pass the video source unchanged to the output.
4176 Apply video transform using libopencv.
4178 To enable this filter install libopencv library and headers and
4179 configure FFmpeg with @code{--enable-libopencv}.
4181 This filter accepts the following parameters:
4186 The name of the libopencv filter to apply.
4189 The parameters to pass to the libopencv filter. If not specified the default
4194 Refer to the official libopencv documentation for more precise
4196 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4198 Follows the list of supported libopencv filters.
4203 Dilate an image by using a specific structuring element.
4204 This filter corresponds to the libopencv function @code{cvDilate}.
4206 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4208 @var{struct_el} represents a structuring element, and has the syntax:
4209 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4211 @var{cols} and @var{rows} represent the number of columns and rows of
4212 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4213 point, and @var{shape} the shape for the structuring element, and
4214 can be one of the values "rect", "cross", "ellipse", "custom".
4216 If the value for @var{shape} is "custom", it must be followed by a
4217 string of the form "=@var{filename}". The file with name
4218 @var{filename} is assumed to represent a binary image, with each
4219 printable character corresponding to a bright pixel. When a custom
4220 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4221 or columns and rows of the read file are assumed instead.
4223 The default value for @var{struct_el} is "3x3+0x0/rect".
4225 @var{nb_iterations} specifies the number of times the transform is
4226 applied to the image, and defaults to 1.
4228 Follow some example:
4230 # use the default values
4233 # dilate using a structuring element with a 5x5 cross, iterate two times
4234 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4236 # read the shape from the file diamond.shape, iterate two times
4237 # the file diamond.shape may contain a pattern of characters like this:
4243 # the specified cols and rows are ignored (but not the anchor point coordinates)
4244 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4249 Erode an image by using a specific structuring element.
4250 This filter corresponds to the libopencv function @code{cvErode}.
4252 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4253 with the same syntax and semantics as the @ref{dilate} filter.
4257 Smooth the input video.
4259 The filter takes the following parameters:
4260 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4262 @var{type} is the type of smooth filter to apply, and can be one of
4263 the following values: "blur", "blur_no_scale", "median", "gaussian",
4264 "bilateral". The default value is "gaussian".
4266 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4267 parameters whose meanings depend on smooth type. @var{param1} and
4268 @var{param2} accept integer positive values or 0, @var{param3} and
4269 @var{param4} accept float values.
4271 The default value for @var{param1} is 3, the default value for the
4272 other parameters is 0.
4274 These parameters correspond to the parameters assigned to the
4275 libopencv function @code{cvSmooth}.
4280 Overlay one video on top of another.
4282 It takes two inputs and one output, the first input is the "main"
4283 video on which the second input is overlayed.
4285 This filter accepts the following parameters:
4287 A description of the accepted options follows.
4292 Set the expression for the x and y coordinates of the overlayed video
4293 on the main video. Default value is "0" for both expressions. In case
4294 the expression is invalid, it is set to a huge value (meaning that the
4295 overlay will not be displayed within the output visible area).
4298 Set the expression which enables the overlay. If the evaluation is
4299 different from 0, the overlay is displayed on top of the input
4300 frame. By default it is "1".
4303 Set when the expressions for @option{x}, @option{y}, and
4304 @option{enable} are evaluated.
4306 It accepts the following values:
4309 only evaluate expressions once during the filter initialization or
4310 when a command is processed
4313 evaluate expressions for each incoming frame
4316 Default value is @samp{frame}.
4319 If set to 1, force the output to terminate when the shortest input
4320 terminates. Default value is 0.
4323 Set the format for the output video.
4325 It accepts the following values:
4337 Default value is @samp{yuv420}.
4339 @item rgb @emph{(deprecated)}
4340 If set to 1, force the filter to accept inputs in the RGB
4341 color space. Default value is 0. This option is deprecated, use
4342 @option{format} instead.
4345 The @option{x}, @option{y}, and @option{enable} expressions can
4346 contain the following parameters.
4351 main input width and height
4355 overlay input width and height
4359 the computed values for @var{x} and @var{y}. They are evaluated for
4364 horizontal and vertical chroma subsample values of the output
4365 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4369 the number of input frame, starting from 0
4372 the position in the file of the input frame, NAN if unknown
4375 timestamp expressed in seconds, NAN if the input timestamp is unknown
4378 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4379 when evaluation is done @emph{per frame}, and will evaluate to NAN
4380 when @option{eval} is set to @samp{init}.
4382 Be aware that frames are taken from each input video in timestamp
4383 order, hence, if their initial timestamps differ, it is a a good idea
4384 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4385 have them begin in the same zero timestamp, as it does the example for
4386 the @var{movie} filter.
4388 You can chain together more overlays but you should test the
4389 efficiency of such approach.
4391 @subsection Commands
4393 This filter supports the following command:
4396 Set the @option{x} option expression.
4399 Set the @option{y} option expression.
4402 Set the @option{enable} option expression.
4405 @subsection Examples
4409 Draw the overlay at 10 pixels from the bottom right corner of the main
4412 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4415 Using named options the example above becomes:
4417 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4421 Insert a transparent PNG logo in the bottom left corner of the input,
4422 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4424 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4428 Insert 2 different transparent PNG logos (second logo on bottom
4429 right corner) using the @command{ffmpeg} tool:
4431 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
4435 Add a transparent color layer on top of the main video, @code{WxH}
4436 must specify the size of the main input to the overlay filter:
4438 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4442 Play an original video and a filtered version (here with the deshake
4443 filter) side by side using the @command{ffplay} tool:
4445 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4448 The above command is the same as:
4450 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4454 Make a sliding overlay appearing from the left to the right top part of the
4455 screen starting since time 2:
4457 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4461 Compose output by putting two input videos side to side:
4463 ffmpeg -i left.avi -i right.avi -filter_complex "
4464 nullsrc=size=200x100 [background];
4465 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4466 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4467 [background][left] overlay=shortest=1 [background+left];
4468 [background+left][right] overlay=shortest=1:x=100 [left+right]
4473 Chain several overlays in cascade:
4475 nullsrc=s=200x200 [bg];
4476 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4477 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4478 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4479 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4480 [in3] null, [mid2] overlay=100:100 [out0]
4487 Add paddings to the input image, and place the original input at the
4488 given coordinates @var{x}, @var{y}.
4490 This filter accepts the following parameters:
4495 Specify an expression for the size of the output image with the
4496 paddings added. If the value for @var{width} or @var{height} is 0, the
4497 corresponding input size is used for the output.
4499 The @var{width} expression can reference the value set by the
4500 @var{height} expression, and vice versa.
4502 The default value of @var{width} and @var{height} is 0.
4506 Specify an expression for the offsets where to place the input image
4507 in the padded area with respect to the top/left border of the output
4510 The @var{x} expression can reference the value set by the @var{y}
4511 expression, and vice versa.
4513 The default value of @var{x} and @var{y} is 0.
4516 Specify the color of the padded area, it can be the name of a color
4517 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4519 The default value of @var{color} is "black".
4522 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4523 options are expressions containing the following constants:
4527 the input video width and height
4530 same as @var{in_w} and @var{in_h}
4533 the output width and height, that is the size of the padded area as
4534 specified by the @var{width} and @var{height} expressions
4537 same as @var{out_w} and @var{out_h}
4540 x and y offsets as specified by the @var{x} and @var{y}
4541 expressions, or NAN if not yet specified
4544 same as @var{iw} / @var{ih}
4547 input sample aspect ratio
4550 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4553 horizontal and vertical chroma subsample values. For example for the
4554 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4557 @subsection Examples
4561 Add paddings with color "violet" to the input video. Output video
4562 size is 640x480, the top-left corner of the input video is placed at
4565 pad=640:480:0:40:violet
4568 The example above is equivalent to the following command:
4570 pad=width=640:height=480:x=0:y=40:color=violet
4574 Pad the input to get an output with dimensions increased by 3/2,
4575 and put the input video at the center of the padded area:
4577 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4581 Pad the input to get a squared output with size equal to the maximum
4582 value between the input width and height, and put the input video at
4583 the center of the padded area:
4585 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4589 Pad the input to get a final w/h ratio of 16:9:
4591 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4595 In case of anamorphic video, in order to set the output display aspect
4596 correctly, it is necessary to use @var{sar} in the expression,
4597 according to the relation:
4599 (ih * X / ih) * sar = output_dar
4600 X = output_dar / sar
4603 Thus the previous example needs to be modified to:
4605 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4609 Double output size and put the input video in the bottom-right
4610 corner of the output padded area:
4612 pad="2*iw:2*ih:ow-iw:oh-ih"
4616 @section pixdesctest
4618 Pixel format descriptor test filter, mainly useful for internal
4619 testing. The output video should be equal to the input video.
4623 format=monow, pixdesctest
4626 can be used to test the monowhite pixel format descriptor definition.
4630 Enable the specified chain of postprocessing subfilters using libpostproc. This
4631 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4632 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4633 Each subfilter and some options have a short and a long name that can be used
4634 interchangeably, i.e. dr/dering are the same.
4636 The filters accept the following options:
4640 Set postprocessing subfilters string.
4643 All subfilters share common options to determine their scope:
4647 Honor the quality commands for this subfilter.
4650 Do chrominance filtering, too (default).
4653 Do luminance filtering only (no chrominance).
4656 Do chrominance filtering only (no luminance).
4659 These options can be appended after the subfilter name, separated by a '|'.
4661 Available subfilters are:
4664 @item hb/hdeblock[|difference[|flatness]]
4665 Horizontal deblocking filter
4668 Difference factor where higher values mean more deblocking (default: @code{32}).
4670 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4673 @item vb/vdeblock[|difference[|flatness]]
4674 Vertical deblocking filter
4677 Difference factor where higher values mean more deblocking (default: @code{32}).
4679 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4682 @item ha/hadeblock[|difference[|flatness]]
4683 Accurate horizontal deblocking filter
4686 Difference factor where higher values mean more deblocking (default: @code{32}).
4688 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4691 @item va/vadeblock[|difference[|flatness]]
4692 Accurate vertical deblocking filter
4695 Difference factor where higher values mean more deblocking (default: @code{32}).
4697 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4701 The horizontal and vertical deblocking filters share the difference and
4702 flatness values so you cannot set different horizontal and vertical
4707 Experimental horizontal deblocking filter
4710 Experimental vertical deblocking filter
4715 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4718 larger -> stronger filtering
4720 larger -> stronger filtering
4722 larger -> stronger filtering
4725 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4728 Stretch luminance to @code{0-255}.
4731 @item lb/linblenddeint
4732 Linear blend deinterlacing filter that deinterlaces the given block by
4733 filtering all lines with a @code{(1 2 1)} filter.
4735 @item li/linipoldeint
4736 Linear interpolating deinterlacing filter that deinterlaces the given block by
4737 linearly interpolating every second line.
4739 @item ci/cubicipoldeint
4740 Cubic interpolating deinterlacing filter deinterlaces the given block by
4741 cubically interpolating every second line.
4743 @item md/mediandeint
4744 Median deinterlacing filter that deinterlaces the given block by applying a
4745 median filter to every second line.
4747 @item fd/ffmpegdeint
4748 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4749 second line with a @code{(-1 4 2 4 -1)} filter.
4752 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4753 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4755 @item fq/forceQuant[|quantizer]
4756 Overrides the quantizer table from the input with the constant quantizer you
4764 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4767 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4770 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4773 @subsection Examples
4777 Apply horizontal and vertical deblocking, deringing and automatic
4778 brightness/contrast:
4784 Apply default filters without brightness/contrast correction:
4790 Apply default filters and temporal denoiser:
4792 pp=default/tmpnoise|1|2|3
4796 Apply deblocking on luminance only, and switch vertical deblocking on or off
4797 automatically depending on available CPU time:
4805 Suppress a TV station logo, using an image file to determine which
4806 pixels comprise the logo. It works by filling in the pixels that
4807 comprise the logo with neighboring pixels.
4809 This filter requires one argument which specifies the filter bitmap
4810 file, which can be any image format supported by libavformat. The
4811 width and height of the image file must match those of the video
4812 stream being processed.
4814 Pixels in the provided bitmap image with a value of zero are not
4815 considered part of the logo, non-zero pixels are considered part of
4816 the logo. If you use white (255) for the logo and black (0) for the
4817 rest, you will be safe. For making the filter bitmap, it is
4818 recommended to take a screen capture of a black frame with the logo
4819 visible, and then using a threshold filter followed by the erode
4820 filter once or twice.
4822 If needed, little splotches can be fixed manually. Remember that if
4823 logo pixels are not covered, the filter quality will be much
4824 reduced. Marking too many pixels as part of the logo does not hurt as
4825 much, but it will increase the amount of blurring needed to cover over
4826 the image and will destroy more information than necessary, and extra
4827 pixels will slow things down on a large logo.
4831 Scale (resize) the input video, using the libswscale library.
4833 The scale filter forces the output display aspect ratio to be the same
4834 of the input, by changing the output sample aspect ratio.
4836 This filter accepts a list of named options in the form of
4837 @var{key}=@var{value} pairs separated by ":". If the key for the first
4838 two options is not specified, the assumed keys for the first two
4839 values are @code{w} and @code{h}. If the first option has no key and
4840 can be interpreted like a video size specification, it will be used
4841 to set the video size.
4843 A description of the accepted options follows.
4848 default value is @code{iw}. See below
4849 for the list of accepted constants.
4852 Output video height.
4853 default value is @code{ih}.
4854 See below for the list of accepted constants.
4857 Set the interlacing. It accepts the following values:
4861 force interlaced aware scaling
4864 do not apply interlaced scaling
4867 select interlaced aware scaling depending on whether the source frames
4868 are flagged as interlaced or not
4871 Default value is @code{0}.
4874 Set libswscale scaling flags. If not explictly specified the filter
4875 applies a bilinear scaling algorithm.
4878 Set the video size, the value must be a valid abbreviation or in the
4879 form @var{width}x@var{height}.
4882 The values of the @var{w} and @var{h} options are expressions
4883 containing the following constants:
4887 the input width and height
4890 same as @var{in_w} and @var{in_h}
4893 the output (cropped) width and height
4896 same as @var{out_w} and @var{out_h}
4899 same as @var{iw} / @var{ih}
4902 input sample aspect ratio
4905 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4908 horizontal and vertical chroma subsample values. For example for the
4909 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4912 If the input image format is different from the format requested by
4913 the next filter, the scale filter will convert the input to the
4916 If the value for @var{w} or @var{h} is 0, the respective input
4917 size is used for the output.
4919 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4920 respective output size, a value that maintains the aspect ratio of the input
4923 @subsection Examples
4927 Scale the input video to a size of 200x100:
4932 This is equivalent to:
4943 Specify a size abbreviation for the output size:
4948 which can also be written as:
4954 Scale the input to 2x:
4960 The above is the same as:
4966 Scale the input to 2x with forced interlaced scaling:
4968 scale=2*iw:2*ih:interl=1
4972 Scale the input to half size:
4978 Increase the width, and set the height to the same size:
4984 Seek for Greek harmony:
4991 Increase the height, and set the width to 3/2 of the height:
4993 scale=w=3/2*oh:h=3/5*ih
4997 Increase the size, but make the size a multiple of the chroma
5000 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
5004 Increase the width to a maximum of 500 pixels, keep the same input
5007 scale=w='min(500\, iw*3/2):h=-1'
5011 @section separatefields
5013 The @code{separatefields} takes a frame-based video input and splits
5014 each frame into its components fields, producing a new half height clip
5015 with twice the frame rate and twice the frame count.
5017 This filter use field-dominance information in frame to decide which
5018 of each pair of fields to place first in the output.
5019 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
5021 @section setdar, setsar
5023 The @code{setdar} filter sets the Display Aspect Ratio for the filter
5026 This is done by changing the specified Sample (aka Pixel) Aspect
5027 Ratio, according to the following equation:
5029 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
5032 Keep in mind that the @code{setdar} filter does not modify the pixel
5033 dimensions of the video frame. Also the display aspect ratio set by
5034 this filter may be changed by later filters in the filterchain,
5035 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5038 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5039 the filter output video.
5041 Note that as a consequence of the application of this filter, the
5042 output display aspect ratio will change according to the equation
5045 Keep in mind that the sample aspect ratio set by the @code{setsar}
5046 filter may be changed by later filters in the filterchain, e.g. if
5047 another "setsar" or a "setdar" filter is applied.
5049 The @code{setdar} and @code{setsar} filters accept a string in the
5050 form @var{num}:@var{den} expressing an aspect ratio, or the following
5051 named options, expressed as a sequence of @var{key}=@var{value} pairs,
5056 Set the maximum integer value to use for expressing numerator and
5057 denominator when reducing the expressed aspect ratio to a rational.
5058 Default value is @code{100}.
5060 @item r, ratio, dar, sar:
5061 Set the aspect ratio used by the filter.
5063 The parameter can be a floating point number string, an expression, or
5064 a string of the form @var{num}:@var{den}, where @var{num} and
5065 @var{den} are the numerator and denominator of the aspect ratio. If
5066 the parameter is not specified, it is assumed the value "0".
5067 In case the form "@var{num}:@var{den}" the @code{:} character should
5071 If the keys are omitted in the named options list, the specifed values
5072 are assumed to be @var{ratio} and @var{max} in that order.
5074 For example to change the display aspect ratio to 16:9, specify:
5077 # the above is equivalent to
5083 To change the sample aspect ratio to 10:11, specify:
5086 # the above is equivalent to
5090 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5091 1000 in the aspect ratio reduction, use the command:
5093 setdar=ratio='16:9':max=1000
5099 Force field for the output video frame.
5101 The @code{setfield} filter marks the interlace type field for the
5102 output frames. It does not change the input frame, but only sets the
5103 corresponding property, which affects how the frame is treated by
5104 following filters (e.g. @code{fieldorder} or @code{yadif}).
5106 The filter accepts the following options:
5111 Available values are:
5115 Keep the same field property.
5118 Mark the frame as bottom-field-first.
5121 Mark the frame as top-field-first.
5124 Mark the frame as progressive.
5130 Show a line containing various information for each input video frame.
5131 The input video is not modified.
5133 The shown line contains a sequence of key/value pairs of the form
5134 @var{key}:@var{value}.
5136 A description of each shown parameter follows:
5140 sequential number of the input frame, starting from 0
5143 Presentation TimeStamp of the input frame, expressed as a number of
5144 time base units. The time base unit depends on the filter input pad.
5147 Presentation TimeStamp of the input frame, expressed as a number of
5151 position of the frame in the input stream, -1 if this information in
5152 unavailable and/or meaningless (for example in case of synthetic video)
5158 sample aspect ratio of the input frame, expressed in the form
5162 size of the input frame, expressed in the form
5163 @var{width}x@var{height}
5166 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5167 for bottom field first)
5170 1 if the frame is a key frame, 0 otherwise
5173 picture type of the input frame ("I" for an I-frame, "P" for a
5174 P-frame, "B" for a B-frame, "?" for unknown type).
5175 Check also the documentation of the @code{AVPictureType} enum and of
5176 the @code{av_get_picture_type_char} function defined in
5177 @file{libavutil/avutil.h}.
5180 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5182 @item plane_checksum
5183 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5184 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5189 Blur the input video without impacting the outlines.
5191 The filter accepts the following options:
5194 @item luma_radius, lr
5195 Set the luma radius. The option value must be a float number in
5196 the range [0.1,5.0] that specifies the variance of the gaussian filter
5197 used to blur the image (slower if larger). Default value is 1.0.
5199 @item luma_strength, ls
5200 Set the luma strength. The option value must be a float number
5201 in the range [-1.0,1.0] that configures the blurring. A value included
5202 in [0.0,1.0] will blur the image whereas a value included in
5203 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5205 @item luma_threshold, lt
5206 Set the luma threshold used as a coefficient to determine
5207 whether a pixel should be blurred or not. The option value must be an
5208 integer in the range [-30,30]. A value of 0 will filter all the image,
5209 a value included in [0,30] will filter flat areas and a value included
5210 in [-30,0] will filter edges. Default value is 0.
5212 @item chroma_radius, cr
5213 Set the chroma radius. The option value must be a float number in
5214 the range [0.1,5.0] that specifies the variance of the gaussian filter
5215 used to blur the image (slower if larger). Default value is 1.0.
5217 @item chroma_strength, cs
5218 Set the chroma strength. The option value must be a float number
5219 in the range [-1.0,1.0] that configures the blurring. A value included
5220 in [0.0,1.0] will blur the image whereas a value included in
5221 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5223 @item chroma_threshold, ct
5224 Set the chroma threshold used as a coefficient to determine
5225 whether a pixel should be blurred or not. The option value must be an
5226 integer in the range [-30,30]. A value of 0 will filter all the image,
5227 a value included in [0,30] will filter flat areas and a value included
5228 in [-30,0] will filter edges. Default value is 0.
5231 If a chroma option is not explicitly set, the corresponding luma value
5236 Convert between different stereoscopic image formats.
5238 The filters accept the following options:
5242 Set stereoscopic image format of input.
5244 Available values for input image formats are:
5247 side by side parallel (left eye left, right eye right)
5250 side by side crosseye (right eye left, left eye right)
5253 side by side parallel with half width resolution
5254 (left eye left, right eye right)
5257 side by side crosseye with half width resolution
5258 (right eye left, left eye right)
5261 above-below (left eye above, right eye below)
5264 above-below (right eye above, left eye below)
5267 above-below with half height resolution
5268 (left eye above, right eye below)
5271 above-below with half height resolution
5272 (right eye above, left eye below)
5274 Default value is @samp{sbsl}.
5278 Set stereoscopic image format of output.
5280 Available values for output image formats are all the input formats as well as:
5283 anaglyph red/blue gray
5284 (red filter on left eye, blue filter on right eye)
5287 anaglyph red/green gray
5288 (red filter on left eye, green filter on right eye)
5291 anaglyph red/cyan gray
5292 (red filter on left eye, cyan filter on right eye)
5295 anaglyph red/cyan half colored
5296 (red filter on left eye, cyan filter on right eye)
5299 anaglyph red/cyan color
5300 (red filter on left eye, cyan filter on right eye)
5303 anaglyph red/cyan color optimized with the least squares projection of dubois
5304 (red filter on left eye, cyan filter on right eye)
5307 anaglyph green/magenta gray
5308 (green filter on left eye, magenta filter on right eye)
5311 anaglyph green/magenta half colored
5312 (green filter on left eye, magenta filter on right eye)
5315 anaglyph green/magenta colored
5316 (green filter on left eye, magenta filter on right eye)
5319 anaglyph green/magenta color optimized with the least squares projection of dubois
5320 (green filter on left eye, magenta filter on right eye)
5323 anaglyph yellow/blue gray
5324 (yellow filter on left eye, blue filter on right eye)
5327 anaglyph yellow/blue half colored
5328 (yellow filter on left eye, blue filter on right eye)
5331 anaglyph yellow/blue colored
5332 (yellow filter on left eye, blue filter on right eye)
5335 anaglyph yellow/blue color optimized with the least squares projection of dubois
5336 (yellow filter on left eye, blue filter on right eye)
5339 interleaved rows (left eye has top row, right eye starts on next row)
5342 interleaved rows (right eye has top row, left eye starts on next row)
5345 mono output (left eye only)
5348 mono output (right eye only)
5351 Default value is @samp{arcd}.
5357 Draw subtitles on top of input video using the libass library.
5359 To enable compilation of this filter you need to configure FFmpeg with
5360 @code{--enable-libass}. This filter also requires a build with libavcodec and
5361 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5362 Alpha) subtitles format.
5364 The filter accepts the following options:
5368 Set the filename of the subtitle file to read. It must be specified.
5371 Specify the size of the original video, the video for which the ASS file
5372 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5373 necessary to correctly scale the fonts if the aspect ratio has been changed.
5376 Set subtitles input character encoding. @code{subtitles} filter only. Only
5377 useful if not UTF-8.
5380 If the first key is not specified, it is assumed that the first value
5381 specifies the @option{filename}.
5383 For example, to render the file @file{sub.srt} on top of the input
5384 video, use the command:
5389 which is equivalent to:
5391 subtitles=filename=sub.srt
5396 Split input video into several identical outputs.
5398 The filter accepts a single parameter which specifies the number of outputs. If
5399 unspecified, it defaults to 2.
5403 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5405 will create 5 copies of the input video.
5409 [in] split [splitout1][splitout2];
5410 [splitout1] crop=100:100:0:0 [cropout];
5411 [splitout2] pad=200:200:100:100 [padout];
5414 will create two separate outputs from the same input, one cropped and
5419 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5420 Interpolate) pixel art scaling algorithm.
5422 Useful for enlarging pixel art images without reducing sharpness.
5428 Select the most representative frame in a given sequence of consecutive frames.
5430 The filter accepts the following options:
5434 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5435 will pick one of them, and then handle the next batch of @var{n} frames until
5436 the end. Default is @code{100}.
5439 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5440 value will result in a higher memory usage, so a high value is not recommended.
5442 @subsection Examples
5446 Extract one picture each 50 frames:
5452 Complete example of a thumbnail creation with @command{ffmpeg}:
5454 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5460 Tile several successive frames together.
5462 The filter accepts the following options:
5467 Set the grid size (i.e. the number of lines and columns) in the form
5471 Set the maximum number of frames to render in the given area. It must be less
5472 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5473 the area will be used.
5476 Set the outer border margin in pixels.
5479 Set the inner border thickness (i.e. the number of pixels between frames). For
5480 more advanced padding options (such as having different values for the edges),
5481 refer to the pad video filter.
5485 @subsection Examples
5489 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5491 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5493 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5494 duplicating each output frame to accomodate the originally detected frame
5498 Display @code{5} pictures in an area of @code{3x2} frames,
5499 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5500 mixed flat and named options:
5502 tile=3x2:nb_frames=5:padding=7:margin=2
5508 Perform various types of temporal field interlacing.
5510 Frames are counted starting from 1, so the first input frame is
5513 The filter accepts the following options:
5518 Specify the mode of the interlacing. This option can also be specified
5519 as a value alone. See below for a list of values for this option.
5521 Available values are:
5525 Move odd frames into the upper field, even into the lower field,
5526 generating a double height frame at half frame rate.
5529 Only output even frames, odd frames are dropped, generating a frame with
5530 unchanged height at half frame rate.
5533 Only output odd frames, even frames are dropped, generating a frame with
5534 unchanged height at half frame rate.
5537 Expand each frame to full height, but pad alternate lines with black,
5538 generating a frame with double height at the same input frame rate.
5540 @item interleave_top, 4
5541 Interleave the upper field from odd frames with the lower field from
5542 even frames, generating a frame with unchanged height at half frame rate.
5544 @item interleave_bottom, 5
5545 Interleave the lower field from odd frames with the upper field from
5546 even frames, generating a frame with unchanged height at half frame rate.
5548 @item interlacex2, 6
5549 Double frame rate with unchanged height. Frames are inserted each
5550 containing the second temporal field from the previous input frame and
5551 the first temporal field from the next input frame. This mode relies on
5552 the top_field_first flag. Useful for interlaced video displays with no
5553 field synchronisation.
5556 Numeric values are deprecated but are accepted for backward
5557 compatibility reasons.
5559 Default mode is @code{merge}.
5562 Specify flags influencing the filter process.
5564 Available value for @var{flags} is:
5567 @item low_pass_filter, vlfp
5568 Enable vertical low-pass filtering in the filter.
5569 Vertical low-pass filtering is required when creating an interlaced
5570 destination from a progressive source which contains high-frequency
5571 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5574 Vertical low-pass filtering can only be enabled for @option{mode}
5575 @var{interleave_top} and @var{interleave_bottom}.
5582 Transpose rows with columns in the input video and optionally flip it.
5584 This filter accepts the following options:
5589 The direction of the transpose.
5592 @item 0, 4, cclock_flip
5593 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5601 Rotate by 90 degrees clockwise, that is:
5609 Rotate by 90 degrees counterclockwise, that is:
5616 @item 3, 7, clock_flip
5617 Rotate by 90 degrees clockwise and vertically flip, that is:
5625 For values between 4-7, the transposition is only done if the input
5626 video geometry is portrait and not landscape. These values are
5627 deprecated, the @code{passthrough} option should be used instead.
5630 Do not apply the transposition if the input geometry matches the one
5631 specified by the specified value. It accepts the following values:
5634 Always apply transposition.
5636 Preserve portrait geometry (when @var{height} >= @var{width}).
5638 Preserve landscape geometry (when @var{width} >= @var{height}).
5641 Default value is @code{none}.
5644 For example to rotate by 90 degrees clockwise and preserve portrait
5647 transpose=dir=1:passthrough=portrait
5650 The command above can also be specified as:
5652 transpose=1:portrait
5657 Sharpen or blur the input video.
5659 It accepts the following parameters:
5662 @item luma_msize_x, lx
5663 @item chroma_msize_x, cx
5664 Set the luma/chroma matrix horizontal size. It must be an odd integer
5665 between 3 and 63, default value is 5.
5667 @item luma_msize_y, ly
5668 @item chroma_msize_y, cy
5669 Set the luma/chroma matrix vertical size. It must be an odd integer
5670 between 3 and 63, default value is 5.
5672 @item luma_amount, la
5673 @item chroma_amount, ca
5674 Set the luma/chroma effect strength. It can be a float number,
5675 reasonable values lay between -1.5 and 1.5.
5677 Negative values will blur the input video, while positive values will
5678 sharpen it, a value of zero will disable the effect.
5680 Default value is 1.0 for @option{luma_amount}, 0.0 for
5681 @option{chroma_amount}.
5684 All parameters are optional and default to the
5685 equivalent of the string '5:5:1.0:5:5:0.0'.
5687 @subsection Examples
5691 Apply strong luma sharpen effect:
5693 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5697 Apply strong blur of both luma and chroma parameters:
5699 unsharp=7:7:-2:7:7:-2
5705 Flip the input video vertically.
5708 ffmpeg -i in.avi -vf "vflip" out.avi
5713 Deinterlace the input video ("yadif" means "yet another deinterlacing
5716 This filter accepts the following options:
5722 The interlacing mode to adopt, accepts one of the following values:
5726 output 1 frame for each frame
5728 output 1 frame for each field
5729 @item 2, send_frame_nospatial
5730 like @code{send_frame} but skip spatial interlacing check
5731 @item 3, send_field_nospatial
5732 like @code{send_field} but skip spatial interlacing check
5735 Default value is @code{send_frame}.
5738 The picture field parity assumed for the input interlaced video, accepts one of
5739 the following values:
5743 assume top field first
5745 assume bottom field first
5747 enable automatic detection
5750 Default value is @code{auto}.
5751 If interlacing is unknown or decoder does not export this information,
5752 top field first will be assumed.
5755 Specify which frames to deinterlace. Accept one of the following
5760 deinterlace all frames
5762 only deinterlace frames marked as interlaced
5765 Default value is @code{all}.
5768 @c man end VIDEO FILTERS
5770 @chapter Video Sources
5771 @c man begin VIDEO SOURCES
5773 Below is a description of the currently available video sources.
5777 Buffer video frames, and make them available to the filter chain.
5779 This source is mainly intended for a programmatic use, in particular
5780 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5782 It accepts a list of options in the form of @var{key}=@var{value} pairs
5783 separated by ":". A description of the accepted options follows.
5788 Specify the size (width and height) of the buffered video frames.
5797 A string representing the pixel format of the buffered video frames.
5798 It may be a number corresponding to a pixel format, or a pixel format
5802 Specify the timebase assumed by the timestamps of the buffered frames.
5805 Specify the frame rate expected for the video stream.
5807 @item pixel_aspect, sar
5808 Specify the sample aspect ratio assumed by the video frames.
5811 Specify the optional parameters to be used for the scale filter which
5812 is automatically inserted when an input change is detected in the
5813 input size or format.
5818 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
5821 will instruct the source to accept video frames with size 320x240 and
5822 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5823 square pixels (1:1 sample aspect ratio).
5824 Since the pixel format with name "yuv410p" corresponds to the number 6
5825 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5826 this example corresponds to:
5828 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5831 Alternatively, the options can be specified as a flat string, but this
5832 syntax is deprecated:
5834 @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}]
5838 Create a pattern generated by an elementary cellular automaton.
5840 The initial state of the cellular automaton can be defined through the
5841 @option{filename}, and @option{pattern} options. If such options are
5842 not specified an initial state is created randomly.
5844 At each new frame a new row in the video is filled with the result of
5845 the cellular automaton next generation. The behavior when the whole
5846 frame is filled is defined by the @option{scroll} option.
5848 This source accepts the following options:
5852 Read the initial cellular automaton state, i.e. the starting row, from
5854 In the file, each non-whitespace character is considered an alive
5855 cell, a newline will terminate the row, and further characters in the
5856 file will be ignored.
5859 Read the initial cellular automaton state, i.e. the starting row, from
5860 the specified string.
5862 Each non-whitespace character in the string is considered an alive
5863 cell, a newline will terminate the row, and further characters in the
5864 string will be ignored.
5867 Set the video rate, that is the number of frames generated per second.
5870 @item random_fill_ratio, ratio
5871 Set the random fill ratio for the initial cellular automaton row. It
5872 is a floating point number value ranging from 0 to 1, defaults to
5875 This option is ignored when a file or a pattern is specified.
5877 @item random_seed, seed
5878 Set the seed for filling randomly the initial row, must be an integer
5879 included between 0 and UINT32_MAX. If not specified, or if explicitly
5880 set to -1, the filter will try to use a good random seed on a best
5884 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5885 Default value is 110.
5888 Set the size of the output video.
5890 If @option{filename} or @option{pattern} is specified, the size is set
5891 by default to the width of the specified initial state row, and the
5892 height is set to @var{width} * PHI.
5894 If @option{size} is set, it must contain the width of the specified
5895 pattern string, and the specified pattern will be centered in the
5898 If a filename or a pattern string is not specified, the size value
5899 defaults to "320x518" (used for a randomly generated initial state).
5902 If set to 1, scroll the output upward when all the rows in the output
5903 have been already filled. If set to 0, the new generated row will be
5904 written over the top row just after the bottom row is filled.
5907 @item start_full, full
5908 If set to 1, completely fill the output with generated rows before
5909 outputting the first frame.
5910 This is the default behavior, for disabling set the value to 0.
5913 If set to 1, stitch the left and right row edges together.
5914 This is the default behavior, for disabling set the value to 0.
5917 @subsection Examples
5921 Read the initial state from @file{pattern}, and specify an output of
5924 cellauto=f=pattern:s=200x400
5928 Generate a random initial row with a width of 200 cells, with a fill
5931 cellauto=ratio=2/3:s=200x200
5935 Create a pattern generated by rule 18 starting by a single alive cell
5936 centered on an initial row with width 100:
5938 cellauto=p=@@:s=100x400:full=0:rule=18
5942 Specify a more elaborated initial pattern:
5944 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5951 Generate a Mandelbrot set fractal, and progressively zoom towards the
5952 point specified with @var{start_x} and @var{start_y}.
5954 This source accepts the following options:
5959 Set the terminal pts value. Default value is 400.
5962 Set the terminal scale value.
5963 Must be a floating point value. Default value is 0.3.
5966 Set the inner coloring mode, that is the algorithm used to draw the
5967 Mandelbrot fractal internal region.
5969 It shall assume one of the following values:
5974 Show time until convergence.
5976 Set color based on point closest to the origin of the iterations.
5981 Default value is @var{mincol}.
5984 Set the bailout value. Default value is 10.0.
5987 Set the maximum of iterations performed by the rendering
5988 algorithm. Default value is 7189.
5991 Set outer coloring mode.
5992 It shall assume one of following values:
5994 @item iteration_count
5995 Set iteration cound mode.
5996 @item normalized_iteration_count
5997 set normalized iteration count mode.
5999 Default value is @var{normalized_iteration_count}.
6002 Set frame rate, expressed as number of frames per second. Default
6006 Set frame size. Default value is "640x480".
6009 Set the initial scale value. Default value is 3.0.
6012 Set the initial x position. Must be a floating point value between
6013 -100 and 100. Default value is -0.743643887037158704752191506114774.
6016 Set the initial y position. Must be a floating point value between
6017 -100 and 100. Default value is -0.131825904205311970493132056385139.
6022 Generate various test patterns, as generated by the MPlayer test filter.
6024 The size of the generated video is fixed, and is 256x256.
6025 This source is useful in particular for testing encoding features.
6027 This source accepts the following options:
6032 Specify the frame rate of the sourced video, as the number of frames
6033 generated per second. It has to be a string in the format
6034 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6035 number or a valid video frame rate abbreviation. The default value is
6039 Set the video duration of the sourced video. The accepted syntax is:
6044 See also the function @code{av_parse_time()}.
6046 If not specified, or the expressed duration is negative, the video is
6047 supposed to be generated forever.
6051 Set the number or the name of the test to perform. Supported tests are:
6066 Default value is "all", which will cycle through the list of all tests.
6069 For example the following:
6074 will generate a "dc_luma" test pattern.
6078 Provide a frei0r source.
6080 To enable compilation of this filter you need to install the frei0r
6081 header and configure FFmpeg with @code{--enable-frei0r}.
6083 This source accepts the following options:
6088 The size of the video to generate, may be a string of the form
6089 @var{width}x@var{height} or a frame size abbreviation.
6092 Framerate of the generated video, may be a string of the form
6093 @var{num}/@var{den} or a frame rate abbreviation.
6096 The name to the frei0r source to load. For more information regarding frei0r and
6097 how to set the parameters read the section @ref{frei0r} in the description of
6101 A '|'-separated list of parameters to pass to the frei0r source.
6105 For example, to generate a frei0r partik0l source with size 200x200
6106 and frame rate 10 which is overlayed on the overlay filter main input:
6108 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6113 Generate a life pattern.
6115 This source is based on a generalization of John Conway's life game.
6117 The sourced input represents a life grid, each pixel represents a cell
6118 which can be in one of two possible states, alive or dead. Every cell
6119 interacts with its eight neighbours, which are the cells that are
6120 horizontally, vertically, or diagonally adjacent.
6122 At each interaction the grid evolves according to the adopted rule,
6123 which specifies the number of neighbor alive cells which will make a
6124 cell stay alive or born. The @option{rule} option allows to specify
6127 This source accepts the following options:
6131 Set the file from which to read the initial grid state. In the file,
6132 each non-whitespace character is considered an alive cell, and newline
6133 is used to delimit the end of each row.
6135 If this option is not specified, the initial grid is generated
6139 Set the video rate, that is the number of frames generated per second.
6142 @item random_fill_ratio, ratio
6143 Set the random fill ratio for the initial random grid. It is a
6144 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6145 It is ignored when a file is specified.
6147 @item random_seed, seed
6148 Set the seed for filling the initial random grid, must be an integer
6149 included between 0 and UINT32_MAX. If not specified, or if explicitly
6150 set to -1, the filter will try to use a good random seed on a best
6156 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6157 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6158 @var{NS} specifies the number of alive neighbor cells which make a
6159 live cell stay alive, and @var{NB} the number of alive neighbor cells
6160 which make a dead cell to become alive (i.e. to "born").
6161 "s" and "b" can be used in place of "S" and "B", respectively.
6163 Alternatively a rule can be specified by an 18-bits integer. The 9
6164 high order bits are used to encode the next cell state if it is alive
6165 for each number of neighbor alive cells, the low order bits specify
6166 the rule for "borning" new cells. Higher order bits encode for an
6167 higher number of neighbor cells.
6168 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6169 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6171 Default value is "S23/B3", which is the original Conway's game of life
6172 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6173 cells, and will born a new cell if there are three alive cells around
6177 Set the size of the output video.
6179 If @option{filename} is specified, the size is set by default to the
6180 same size of the input file. If @option{size} is set, it must contain
6181 the size specified in the input file, and the initial grid defined in
6182 that file is centered in the larger resulting area.
6184 If a filename is not specified, the size value defaults to "320x240"
6185 (used for a randomly generated initial grid).
6188 If set to 1, stitch the left and right grid edges together, and the
6189 top and bottom edges also. Defaults to 1.
6192 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6193 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6194 value from 0 to 255.
6197 Set the color of living (or new born) cells.
6200 Set the color of dead cells. If @option{mold} is set, this is the first color
6201 used to represent a dead cell.
6204 Set mold color, for definitely dead and moldy cells.
6207 @subsection Examples
6211 Read a grid from @file{pattern}, and center it on a grid of size
6214 life=f=pattern:s=300x300
6218 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6220 life=ratio=2/3:s=200x200
6224 Specify a custom rule for evolving a randomly generated grid:
6230 Full example with slow death effect (mold) using @command{ffplay}:
6232 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6236 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6238 The @code{color} source provides an uniformly colored input.
6240 The @code{nullsrc} source returns unprocessed video frames. It is
6241 mainly useful to be employed in analysis / debugging tools, or as the
6242 source for filters which ignore the input data.
6244 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6245 detecting RGB vs BGR issues. You should see a red, green and blue
6246 stripe from top to bottom.
6248 The @code{smptebars} source generates a color bars pattern, based on
6249 the SMPTE Engineering Guideline EG 1-1990.
6251 The @code{testsrc} source generates a test video pattern, showing a
6252 color pattern, a scrolling gradient and a timestamp. This is mainly
6253 intended for testing purposes.
6255 The sources accept the following options:
6260 Specify the color of the source, only used in the @code{color}
6261 source. It can be the name of a color (case insensitive match) or a
6262 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6263 default value is "black".
6266 Specify the size of the sourced video, it may be a string of the form
6267 @var{width}x@var{height}, or the name of a size abbreviation. The
6268 default value is "320x240".
6271 Specify the frame rate of the sourced video, as the number of frames
6272 generated per second. It has to be a string in the format
6273 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6274 number or a valid video frame rate abbreviation. The default value is
6278 Set the sample aspect ratio of the sourced video.
6281 Set the video duration of the sourced video. The accepted syntax is:
6283 [-]HH[:MM[:SS[.m...]]]
6286 See also the function @code{av_parse_time()}.
6288 If not specified, or the expressed duration is negative, the video is
6289 supposed to be generated forever.
6292 Set the number of decimals to show in the timestamp, only used in the
6293 @code{testsrc} source.
6295 The displayed timestamp value will correspond to the original
6296 timestamp value multiplied by the power of 10 of the specified
6297 value. Default value is 0.
6300 For example the following:
6302 testsrc=duration=5.3:size=qcif:rate=10
6305 will generate a video with a duration of 5.3 seconds, with size
6306 176x144 and a frame rate of 10 frames per second.
6308 The following graph description will generate a red source
6309 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6312 color=c=red@@0.2:s=qcif:r=10
6315 If the input content is to be ignored, @code{nullsrc} can be used. The
6316 following command generates noise in the luminance plane by employing
6317 the @code{geq} filter:
6319 nullsrc=s=256x256, geq=random(1)*255:128:128
6322 @c man end VIDEO SOURCES
6324 @chapter Video Sinks
6325 @c man begin VIDEO SINKS
6327 Below is a description of the currently available video sinks.
6331 Buffer video frames, and make them available to the end of the filter
6334 This sink is mainly intended for a programmatic use, in particular
6335 through the interface defined in @file{libavfilter/buffersink.h}.
6337 It does not require a string parameter in input, but you need to
6338 specify a pointer to a list of supported pixel formats terminated by
6339 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6340 when initializing this sink.
6344 Null video sink, do absolutely nothing with the input video. It is
6345 mainly useful as a template and to be employed in analysis / debugging
6348 @c man end VIDEO SINKS
6350 @chapter Multimedia Filters
6351 @c man begin MULTIMEDIA FILTERS
6353 Below is a description of the currently available multimedia filters.
6355 @section aperms, perms
6357 Set read/write permissions for the output frames.
6359 These filters are mainly aimed at developers to test direct path in the
6360 following filter in the filtergraph.
6362 The filters accept the following options:
6366 Select the permissions mode.
6368 It accepts the following values:
6371 Do nothing. This is the default.
6373 Set all the output frames read-only.
6375 Set all the output frames directly writable.
6377 Make the frame read-only if writable, and writable if read-only.
6379 Set each output frame read-only or writable randomly.
6383 Set the seed for the @var{random} mode, must be an integer included between
6384 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6385 @code{-1}, the filter will try to use a good random seed on a best effort
6389 Note: in case of auto-inserted filter between the permission filter and the
6390 following one, the permission might not be received as expected in that
6391 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6392 perms/aperms filter can avoid this problem.
6395 Add a phasing effect to the input audio.
6397 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6398 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6400 A description of the accepted parameters follows.
6404 Set input gain. Default is 0.4.
6407 Set output gain. Default is 0.74
6410 Set delay in milliseconds. Default is 3.0.
6413 Set decay. Default is 0.4.
6416 Set modulation speed in Hz. Default is 0.5.
6419 Set modulation type. Default is triangular.
6421 It accepts the following values:
6428 @section aselect, select
6429 Select frames to pass in output.
6431 This filter accepts the following options:
6436 An expression, which is evaluated for each input frame. If the expression is
6437 evaluated to a non-zero value, the frame is selected and passed to the output,
6438 otherwise it is discarded.
6442 The expression can contain the following constants:
6446 the sequential number of the filtered frame, starting from 0
6449 the sequential number of the selected frame, starting from 0
6451 @item prev_selected_n
6452 the sequential number of the last selected frame, NAN if undefined
6455 timebase of the input timestamps
6458 the PTS (Presentation TimeStamp) of the filtered video frame,
6459 expressed in @var{TB} units, NAN if undefined
6462 the PTS (Presentation TimeStamp) of the filtered video frame,
6463 expressed in seconds, NAN if undefined
6466 the PTS of the previously filtered video frame, NAN if undefined
6468 @item prev_selected_pts
6469 the PTS of the last previously filtered video frame, NAN if undefined
6471 @item prev_selected_t
6472 the PTS of the last previously selected video frame, NAN if undefined
6475 the PTS of the first video frame in the video, NAN if undefined
6478 the time of the first video frame in the video, NAN if undefined
6480 @item pict_type @emph{(video only)}
6481 the type of the filtered frame, can assume one of the following
6493 @item interlace_type @emph{(video only)}
6494 the frame interlace type, can assume one of the following values:
6497 the frame is progressive (not interlaced)
6499 the frame is top-field-first
6501 the frame is bottom-field-first
6504 @item consumed_sample_n @emph{(audio only)}
6505 the number of selected samples before the current frame
6507 @item samples_n @emph{(audio only)}
6508 the number of samples in the current frame
6510 @item sample_rate @emph{(audio only)}
6511 the input sample rate
6514 1 if the filtered frame is a key-frame, 0 otherwise
6517 the position in the file of the filtered frame, -1 if the information
6518 is not available (e.g. for synthetic video)
6520 @item scene @emph{(video only)}
6521 value between 0 and 1 to indicate a new scene; a low value reflects a low
6522 probability for the current frame to introduce a new scene, while a higher
6523 value means the current frame is more likely to be one (see the example below)
6527 The default value of the select expression is "1".
6529 @subsection Examples
6533 Select all frames in input:
6538 The example above is the same as:
6550 Select only I-frames:
6552 select='eq(pict_type\,I)'
6556 Select one frame every 100:
6558 select='not(mod(n\,100))'
6562 Select only frames contained in the 10-20 time interval:
6564 select='gte(t\,10)*lte(t\,20)'
6568 Select only I frames contained in the 10-20 time interval:
6570 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6574 Select frames with a minimum distance of 10 seconds:
6576 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6580 Use aselect to select only audio frames with samples number > 100:
6582 aselect='gt(samples_n\,100)'
6586 Create a mosaic of the first scenes:
6588 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6591 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6595 @section asendcmd, sendcmd
6597 Send commands to filters in the filtergraph.
6599 These filters read commands to be sent to other filters in the
6602 @code{asendcmd} must be inserted between two audio filters,
6603 @code{sendcmd} must be inserted between two video filters, but apart
6604 from that they act the same way.
6606 The specification of commands can be provided in the filter arguments
6607 with the @var{commands} option, or in a file specified by the
6608 @var{filename} option.
6610 These filters accept the following options:
6613 Set the commands to be read and sent to the other filters.
6615 Set the filename of the commands to be read and sent to the other
6619 @subsection Commands syntax
6621 A commands description consists of a sequence of interval
6622 specifications, comprising a list of commands to be executed when a
6623 particular event related to that interval occurs. The occurring event
6624 is typically the current frame time entering or leaving a given time
6627 An interval is specified by the following syntax:
6629 @var{START}[-@var{END}] @var{COMMANDS};
6632 The time interval is specified by the @var{START} and @var{END} times.
6633 @var{END} is optional and defaults to the maximum time.
6635 The current frame time is considered within the specified interval if
6636 it is included in the interval [@var{START}, @var{END}), that is when
6637 the time is greater or equal to @var{START} and is lesser than
6640 @var{COMMANDS} consists of a sequence of one or more command
6641 specifications, separated by ",", relating to that interval. The
6642 syntax of a command specification is given by:
6644 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6647 @var{FLAGS} is optional and specifies the type of events relating to
6648 the time interval which enable sending the specified command, and must
6649 be a non-null sequence of identifier flags separated by "+" or "|" and
6650 enclosed between "[" and "]".
6652 The following flags are recognized:
6655 The command is sent when the current frame timestamp enters the
6656 specified interval. In other words, the command is sent when the
6657 previous frame timestamp was not in the given interval, and the
6661 The command is sent when the current frame timestamp leaves the
6662 specified interval. In other words, the command is sent when the
6663 previous frame timestamp was in the given interval, and the
6667 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6670 @var{TARGET} specifies the target of the command, usually the name of
6671 the filter class or a specific filter instance name.
6673 @var{COMMAND} specifies the name of the command for the target filter.
6675 @var{ARG} is optional and specifies the optional list of argument for
6676 the given @var{COMMAND}.
6678 Between one interval specification and another, whitespaces, or
6679 sequences of characters starting with @code{#} until the end of line,
6680 are ignored and can be used to annotate comments.
6682 A simplified BNF description of the commands specification syntax
6685 @var{COMMAND_FLAG} ::= "enter" | "leave"
6686 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6687 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6688 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6689 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6690 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6693 @subsection Examples
6697 Specify audio tempo change at second 4:
6699 asendcmd=c='4.0 atempo tempo 1.5',atempo
6703 Specify a list of drawtext and hue commands in a file.
6705 # show text in the interval 5-10
6706 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6707 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6709 # desaturate the image in the interval 15-20
6710 15.0-20.0 [enter] hue reinit s=0,
6711 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6712 [leave] hue reinit s=1,
6713 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6715 # apply an exponential saturation fade-out effect, starting from time 25
6716 25 [enter] hue s=exp(t-25)
6719 A filtergraph allowing to read and process the above command list
6720 stored in a file @file{test.cmd}, can be specified with:
6722 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6727 @section asetpts, setpts
6729 Change the PTS (presentation timestamp) of the input frames.
6731 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6733 This filter accepts the following options:
6738 The expression which is evaluated for each frame to construct its timestamp.
6742 The expression is evaluated through the eval API and can contain the following
6747 frame rate, only defined for constant frame-rate video
6750 the presentation timestamp in input
6753 the count of the input frame, starting from 0.
6755 @item NB_CONSUMED_SAMPLES
6756 the number of consumed samples, not including the current frame (only
6760 the number of samples in the current frame (only audio)
6766 the PTS of the first frame
6769 the time in seconds of the first frame
6772 tell if the current frame is interlaced
6775 the time in seconds of the current frame
6781 original position in the file of the frame, or undefined if undefined
6782 for the current frame
6788 previous input time in seconds
6794 previous output time in seconds
6797 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6801 wallclock (RTC) time at the start of the movie in microseconds
6804 @subsection Examples
6808 Start counting PTS from zero
6814 Apply fast motion effect:
6820 Apply slow motion effect:
6826 Set fixed rate of 25 frames per second:
6832 Set fixed rate 25 fps with some jitter:
6834 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6838 Apply an offset of 10 seconds to the input PTS:
6844 Generate timestamps from a "live source" and rebase onto the current timebase:
6846 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6852 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6853 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6854 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6855 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6857 The filter also has a video output (see the @var{video} option) with a real
6858 time graph to observe the loudness evolution. The graphic contains the logged
6859 message mentioned above, so it is not printed anymore when this option is set,
6860 unless the verbose logging is set. The main graphing area contains the
6861 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6862 the momentary loudness (400 milliseconds).
6864 More information about the Loudness Recommendation EBU R128 on
6865 @url{http://tech.ebu.ch/loudness}.
6867 The filter accepts the following options:
6872 Activate the video output. The audio stream is passed unchanged whether this
6873 option is set or no. The video stream will be the first output stream if
6874 activated. Default is @code{0}.
6877 Set the video size. This option is for video only. Default and minimum
6878 resolution is @code{640x480}.
6881 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6882 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6883 other integer value between this range is allowed.
6886 Set metadata injection. If set to @code{1}, the audio input will be segmented
6887 into 100ms output frames, each of them containing various loudness information
6888 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6890 Default is @code{0}.
6893 Force the frame logging level.
6895 Available values are:
6898 information logging level
6900 verbose logging level
6903 By default, the logging level is set to @var{info}. If the @option{video} or
6904 the @option{metadata} options are set, it switches to @var{verbose}.
6907 @subsection Examples
6911 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6913 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6917 Run an analysis with @command{ffmpeg}:
6919 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6923 @section settb, asettb
6925 Set the timebase to use for the output frames timestamps.
6926 It is mainly useful for testing timebase configuration.
6928 This filter accepts the following options:
6933 The expression which is evaluated into the output timebase.
6937 The value for @option{tb} is an arithmetic expression representing a
6938 rational. The expression can contain the constants "AVTB" (the default
6939 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6940 audio only). Default value is "intb".
6942 @subsection Examples
6946 Set the timebase to 1/25:
6952 Set the timebase to 1/10:
6958 Set the timebase to 1001/1000:
6964 Set the timebase to 2*intb:
6970 Set the default timebase value:
6978 Concatenate audio and video streams, joining them together one after the
6981 The filter works on segments of synchronized video and audio streams. All
6982 segments must have the same number of streams of each type, and that will
6983 also be the number of streams at output.
6985 The filter accepts the following options:
6990 Set the number of segments. Default is 2.
6993 Set the number of output video streams, that is also the number of video
6994 streams in each segment. Default is 1.
6997 Set the number of output audio streams, that is also the number of video
6998 streams in each segment. Default is 0.
7001 Activate unsafe mode: do not fail if segments have a different format.
7005 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
7006 @var{a} audio outputs.
7008 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
7009 segment, in the same order as the outputs, then the inputs for the second
7012 Related streams do not always have exactly the same duration, for various
7013 reasons including codec frame size or sloppy authoring. For that reason,
7014 related synchronized streams (e.g. a video and its audio track) should be
7015 concatenated at once. The concat filter will use the duration of the longest
7016 stream in each segment (except the last one), and if necessary pad shorter
7017 audio streams with silence.
7019 For this filter to work correctly, all segments must start at timestamp 0.
7021 All corresponding streams must have the same parameters in all segments; the
7022 filtering system will automatically select a common pixel format for video
7023 streams, and a common sample format, sample rate and channel layout for
7024 audio streams, but other settings, such as resolution, must be converted
7025 explicitly by the user.
7027 Different frame rates are acceptable but will result in variable frame rate
7028 at output; be sure to configure the output file to handle it.
7030 @subsection Examples
7034 Concatenate an opening, an episode and an ending, all in bilingual version
7035 (video in stream 0, audio in streams 1 and 2):
7037 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
7038 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7039 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7040 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7044 Concatenate two parts, handling audio and video separately, using the
7045 (a)movie sources, and adjusting the resolution:
7047 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7048 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7049 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7051 Note that a desync will happen at the stitch if the audio and video streams
7052 do not have exactly the same duration in the first file.
7056 @section showspectrum
7058 Convert input audio to a video output, representing the audio frequency
7061 The filter accepts the following options:
7065 Specify the video size for the output. Default value is @code{640x512}.
7068 Specify if the spectrum should slide along the window. Default value is
7072 Specify display mode.
7074 It accepts the following values:
7077 all channels are displayed in the same row
7079 all channels are displayed in separate rows
7082 Default value is @samp{combined}.
7085 Specify display color mode.
7087 It accepts the following values:
7090 each channel is displayed in a separate color
7092 each channel is is displayed using the same color scheme
7095 Default value is @samp{channel}.
7098 Specify scale used for calculating intensity color values.
7100 It accepts the following values:
7105 square root, default
7112 Default value is @samp{sqrt}.
7115 Set saturation modifier for displayed colors. Negative values provide
7116 alternative color scheme. @code{0} is no saturation at all.
7117 Saturation must be in [-10.0, 10.0] range.
7118 Default value is @code{1}.
7121 The usage is very similar to the showwaves filter; see the examples in that
7124 @subsection Examples
7128 Large window with logarithmic color scaling:
7130 showspectrum=s=1280x480:scale=log
7134 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7136 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7137 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7143 Convert input audio to a video output, representing the samples waves.
7145 The filter accepts the following options:
7149 Specify the video size for the output. Default value is "600x240".
7154 Available values are:
7157 Draw a point for each sample.
7160 Draw a vertical line for each sample.
7163 Default value is @code{point}.
7166 Set the number of samples which are printed on the same column. A
7167 larger value will decrease the frame rate. Must be a positive
7168 integer. This option can be set only if the value for @var{rate}
7169 is not explicitly specified.
7172 Set the (approximate) output frame rate. This is done by setting the
7173 option @var{n}. Default value is "25".
7177 @subsection Examples
7181 Output the input file audio and the corresponding video representation
7184 amovie=a.mp3,asplit[out0],showwaves[out1]
7188 Create a synthetic signal and show it with showwaves, forcing a
7189 frame rate of 30 frames per second:
7191 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7195 @c man end MULTIMEDIA FILTERS
7197 @chapter Multimedia Sources
7198 @c man begin MULTIMEDIA SOURCES
7200 Below is a description of the currently available multimedia sources.
7204 This is the same as @ref{movie} source, except it selects an audio
7210 Read audio and/or video stream(s) from a movie container.
7212 This filter accepts the following options:
7216 The name of the resource to read (not necessarily a file but also a device or a
7217 stream accessed through some protocol).
7219 @item format_name, f
7220 Specifies the format assumed for the movie to read, and can be either
7221 the name of a container or an input device. If not specified the
7222 format is guessed from @var{movie_name} or by probing.
7224 @item seek_point, sp
7225 Specifies the seek point in seconds, the frames will be output
7226 starting from this seek point, the parameter is evaluated with
7227 @code{av_strtod} so the numerical value may be suffixed by an IS
7228 postfix. Default value is "0".
7231 Specifies the streams to read. Several streams can be specified,
7232 separated by "+". The source will then have as many outputs, in the
7233 same order. The syntax is explained in the ``Stream specifiers''
7234 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7235 respectively the default (best suited) video and audio stream. Default
7236 is "dv", or "da" if the filter is called as "amovie".
7238 @item stream_index, si
7239 Specifies the index of the video stream to read. If the value is -1,
7240 the best suited video stream will be automatically selected. Default
7241 value is "-1". Deprecated. If the filter is called "amovie", it will select
7242 audio instead of video.
7245 Specifies how many times to read the stream in sequence.
7246 If the value is less than 1, the stream will be read again and again.
7247 Default value is "1".
7249 Note that when the movie is looped the source timestamps are not
7250 changed, so it will generate non monotonically increasing timestamps.
7253 This filter allows to overlay a second video on top of main input of
7254 a filtergraph as shown in this graph:
7256 input -----------> deltapts0 --> overlay --> output
7259 movie --> scale--> deltapts1 -------+
7262 @subsection Examples
7266 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7267 on top of the input labelled as "in":
7269 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7270 [in] setpts=PTS-STARTPTS [main];
7271 [main][over] overlay=16:16 [out]
7275 Read from a video4linux2 device, and overlay it on top of the input
7278 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7279 [in] setpts=PTS-STARTPTS [main];
7280 [main][over] overlay=16:16 [out]
7284 Read the first video stream and the audio stream with id 0x81 from
7285 dvd.vob; the video is connected to the pad named "video" and the audio is
7286 connected to the pad named "audio":
7288 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7292 @c man end MULTIMEDIA SOURCES