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 the following options:
909 @item nb_out_samples, n
910 Set the number of frames per each output audio frame. The number is
911 intended as the number of samples @emph{per each channel}.
912 Default value is 1024.
915 If set to 1, the filter will pad the last audio frame with zeroes, so
916 that the last frame will contain the same number of samples as the
917 previous ones. Default value is 1.
920 For example, to set the number of per-frame samples to 1234 and
921 disable padding for the last frame, use:
923 asetnsamples=n=1234:p=0
928 Show a line containing various information for each input audio frame.
929 The input audio is not modified.
931 The shown line contains a sequence of key/value pairs of the form
932 @var{key}:@var{value}.
934 A description of each shown parameter follows:
938 sequential number of the input frame, starting from 0
941 Presentation timestamp of the input frame, in time base units; the time base
942 depends on the filter input pad, and is usually 1/@var{sample_rate}.
945 presentation timestamp of the input frame in seconds
948 position of the frame in the input stream, -1 if this information in
949 unavailable and/or meaningless (for example in case of synthetic audio)
958 sample rate for the audio frame
961 number of samples (per channel) in the frame
964 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
965 the data is treated as if all the planes were concatenated.
967 @item plane_checksums
968 A list of Adler-32 checksums for each data plane.
973 Split input audio into several identical outputs.
975 The filter accepts a single parameter which specifies the number of outputs. If
976 unspecified, it defaults to 2.
980 [in] asplit [out0][out1]
983 will create two separate outputs from the same input.
985 To create 3 or more outputs, you need to specify the number of
988 [in] asplit=3 [out0][out1][out2]
992 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
994 will create 5 copies of the input audio.
999 Forward two audio streams and control the order the buffers are forwarded.
1001 The filter accepts the following options:
1005 Set the expression deciding which stream should be
1006 forwarded next: if the result is negative, the first stream is forwarded; if
1007 the result is positive or zero, the second stream is forwarded. It can use
1008 the following variables:
1012 number of buffers forwarded so far on each stream
1014 number of samples forwarded so far on each stream
1016 current timestamp of each stream
1019 The default value is @code{t1-t2}, which means to always forward the stream
1020 that has a smaller timestamp.
1023 @subsection Examples
1025 Stress-test @code{amerge} by randomly sending buffers on the wrong
1026 input, while avoiding too much of a desynchronization:
1028 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1029 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1037 The filter accepts exactly one parameter, the audio tempo. If not
1038 specified then the filter will assume nominal 1.0 tempo. Tempo must
1039 be in the [0.5, 2.0] range.
1041 @subsection Examples
1045 Slow down audio to 80% tempo:
1051 To speed up audio to 125% tempo:
1059 Make audio easier to listen to on headphones.
1061 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1062 so that when listened to on headphones the stereo image is moved from
1063 inside your head (standard for headphones) to outside and in front of
1064 the listener (standard for speakers).
1070 Mix channels with specific gain levels. The filter accepts the output
1071 channel layout followed by a set of channels definitions.
1073 This filter is also designed to remap efficiently the channels of an audio
1076 The filter accepts parameters of the form:
1077 "@var{l}:@var{outdef}:@var{outdef}:..."
1081 output channel layout or number of channels
1084 output channel specification, of the form:
1085 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1088 output channel to define, either a channel name (FL, FR, etc.) or a channel
1089 number (c0, c1, etc.)
1092 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1095 input channel to use, see out_name for details; it is not possible to mix
1096 named and numbered input channels
1099 If the `=' in a channel specification is replaced by `<', then the gains for
1100 that specification will be renormalized so that the total is 1, thus
1101 avoiding clipping noise.
1103 @subsection Mixing examples
1105 For example, if you want to down-mix from stereo to mono, but with a bigger
1106 factor for the left channel:
1108 pan=1:c0=0.9*c0+0.1*c1
1111 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1112 7-channels surround:
1114 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1117 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1118 that should be preferred (see "-ac" option) unless you have very specific
1121 @subsection Remapping examples
1123 The channel remapping will be effective if, and only if:
1126 @item gain coefficients are zeroes or ones,
1127 @item only one input per channel output,
1130 If all these conditions are satisfied, the filter will notify the user ("Pure
1131 channel mapping detected"), and use an optimized and lossless method to do the
1134 For example, if you have a 5.1 source and want a stereo audio stream by
1135 dropping the extra channels:
1137 pan="stereo: c0=FL : c1=FR"
1140 Given the same source, you can also switch front left and front right channels
1141 and keep the input channel layout:
1143 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1146 If the input is a stereo audio stream, you can mute the front left channel (and
1147 still keep the stereo channel layout) with:
1152 Still with a stereo audio stream input, you can copy the right channel in both
1153 front left and right:
1155 pan="stereo: c0=FR : c1=FR"
1158 @section silencedetect
1160 Detect silence in an audio stream.
1162 This filter logs a message when it detects that the input audio volume is less
1163 or equal to a noise tolerance value for a duration greater or equal to the
1164 minimum detected noise duration.
1166 The printed times and duration are expressed in seconds.
1168 The filter accepts the following options:
1172 Set silence duration until notification (default is 2 seconds).
1175 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1176 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1179 @subsection Examples
1183 Detect 5 seconds of silence with -50dB noise tolerance:
1185 silencedetect=n=-50dB:d=5
1189 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1190 tolerance in @file{silence.mp3}:
1192 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1197 Synchronize audio data with timestamps by squeezing/stretching it and/or
1198 dropping samples/adding silence when needed.
1200 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1202 The filter accepts the following named parameters:
1206 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1207 by default. When disabled, time gaps are covered with silence.
1210 Minimum difference between timestamps and audio data (in seconds) to trigger
1211 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1212 this filter, try setting this parameter to 0.
1215 Maximum compensation in samples per second. Relevant only with compensate=1.
1219 Assume the first pts should be this value. The time base is 1 / sample rate.
1220 This allows for padding/trimming at the start of stream. By default, no
1221 assumption is made about the first frame's expected pts, so no padding or
1222 trimming is done. For example, this could be set to 0 to pad the beginning with
1223 silence if an audio stream starts after the video stream or to trim any samples
1224 with a negative pts due to encoder delay.
1228 @section channelsplit
1229 Split each channel in input audio stream into a separate output stream.
1231 This filter accepts the following named parameters:
1233 @item channel_layout
1234 Channel layout of the input stream. Default is "stereo".
1237 For example, assuming a stereo input MP3 file
1239 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1241 will create an output Matroska file with two audio streams, one containing only
1242 the left channel and the other the right channel.
1244 To split a 5.1 WAV file into per-channel files
1246 ffmpeg -i in.wav -filter_complex
1247 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1248 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1249 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1254 Remap input channels to new locations.
1256 This filter accepts the following named parameters:
1258 @item channel_layout
1259 Channel layout of the output stream.
1262 Map channels from input to output. The argument is a '|'-separated list of
1263 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1264 @var{in_channel} form. @var{in_channel} can be either the name of the input
1265 channel (e.g. FL for front left) or its index in the input channel layout.
1266 @var{out_channel} is the name of the output channel or its index in the output
1267 channel layout. If @var{out_channel} is not given then it is implicitly an
1268 index, starting with zero and increasing by one for each mapping.
1271 If no mapping is present, the filter will implicitly map input channels to
1272 output channels preserving index.
1274 For example, assuming a 5.1+downmix input MOV file
1276 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1278 will create an output WAV file tagged as stereo from the downmix channels of
1281 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1283 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1287 Join multiple input streams into one multi-channel stream.
1289 The filter accepts the following named parameters:
1293 Number of input streams. Defaults to 2.
1295 @item channel_layout
1296 Desired output channel layout. Defaults to stereo.
1299 Map channels from inputs to output. The argument is a '|'-separated list of
1300 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1301 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1302 can be either the name of the input channel (e.g. FL for front left) or its
1303 index in the specified input stream. @var{out_channel} is the name of the output
1307 The filter will attempt to guess the mappings when those are not specified
1308 explicitly. It does so by first trying to find an unused matching input channel
1309 and if that fails it picks the first unused input channel.
1311 E.g. to join 3 inputs (with properly set channel layouts)
1313 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1316 To build a 5.1 output from 6 single-channel streams:
1318 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1319 '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'
1324 Convert the audio sample format, sample rate and channel layout. This filter is
1325 not meant to be used directly.
1329 Adjust the input audio volume.
1331 The filter accepts the following named parameters. If the key of the
1332 first options is omitted, the arguments are interpreted according to
1333 the following syntax:
1335 volume=@var{volume}:@var{precision}
1341 Expresses how the audio volume will be increased or decreased.
1343 Output values are clipped to the maximum value.
1345 The output audio volume is given by the relation:
1347 @var{output_volume} = @var{volume} * @var{input_volume}
1350 Default value for @var{volume} is 1.0.
1353 Set the mathematical precision.
1355 This determines which input sample formats will be allowed, which affects the
1356 precision of the volume scaling.
1360 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1362 32-bit floating-point; limits input sample format to FLT. (default)
1364 64-bit floating-point; limits input sample format to DBL.
1368 @subsection Examples
1372 Halve the input audio volume:
1376 volume=volume=-6.0206dB
1379 In all the above example the named key for @option{volume} can be
1380 omitted, for example like in:
1386 Increase input audio power by 6 decibels using fixed-point precision:
1388 volume=volume=6dB:precision=fixed
1392 @section volumedetect
1394 Detect the volume of the input video.
1396 The filter has no parameters. The input is not modified. Statistics about
1397 the volume will be printed in the log when the input stream end is reached.
1399 In particular it will show the mean volume (root mean square), maximum
1400 volume (on a per-sample basis), and the beginning of an histogram of the
1401 registered volume values (from the maximum value to a cumulated 1/1000 of
1404 All volumes are in decibels relative to the maximum PCM value.
1406 @subsection Examples
1408 Here is an excerpt of the output:
1410 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1411 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1412 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1413 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1414 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1415 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1416 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1417 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1418 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1424 The mean square energy is approximately -27 dB, or 10^-2.7.
1426 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1428 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1431 In other words, raising the volume by +4 dB does not cause any clipping,
1432 raising it by +5 dB causes clipping for 6 samples, etc.
1434 @c man end AUDIO FILTERS
1436 @chapter Audio Sources
1437 @c man begin AUDIO SOURCES
1439 Below is a description of the currently available audio sources.
1443 Buffer audio frames, and make them available to the filter chain.
1445 This source is mainly intended for a programmatic use, in particular
1446 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1448 It accepts the following named parameters:
1453 Timebase which will be used for timestamps of submitted frames. It must be
1454 either a floating-point number or in @var{numerator}/@var{denominator} form.
1457 The sample rate of the incoming audio buffers.
1460 The sample format of the incoming audio buffers.
1461 Either a sample format name or its corresponging integer representation from
1462 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1464 @item channel_layout
1465 The channel layout of the incoming audio buffers.
1466 Either a channel layout name from channel_layout_map in
1467 @file{libavutil/channel_layout.c} or its corresponding integer representation
1468 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1471 The number of channels of the incoming audio buffers.
1472 If both @var{channels} and @var{channel_layout} are specified, then they
1477 @subsection Examples
1480 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1483 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1484 Since the sample format with name "s16p" corresponds to the number
1485 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1488 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1493 Generate an audio signal specified by an expression.
1495 This source accepts in input one or more expressions (one for each
1496 channel), which are evaluated and used to generate a corresponding
1499 This source accepts the following options:
1503 Set the '|'-separated expressions list for each separate channel. In case the
1504 @option{channel_layout} option is not specified, the selected channel layout
1505 depends on the number of provided expressions.
1507 @item channel_layout, c
1508 Set the channel layout. The number of channels in the specified layout
1509 must be equal to the number of specified expressions.
1512 Set the minimum duration of the sourced audio. See the function
1513 @code{av_parse_time()} for the accepted format.
1514 Note that the resulting duration may be greater than the specified
1515 duration, as the generated audio is always cut at the end of a
1518 If not specified, or the expressed duration is negative, the audio is
1519 supposed to be generated forever.
1522 Set the number of samples per channel per each output frame,
1525 @item sample_rate, s
1526 Specify the sample rate, default to 44100.
1529 Each expression in @var{exprs} can contain the following constants:
1533 number of the evaluated sample, starting from 0
1536 time of the evaluated sample expressed in seconds, starting from 0
1543 @subsection Examples
1553 Generate a sin signal with frequency of 440 Hz, set sample rate to
1556 aevalsrc="sin(440*2*PI*t):s=8000"
1560 Generate a two channels signal, specify the channel layout (Front
1561 Center + Back Center) explicitly:
1563 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
1567 Generate white noise:
1569 aevalsrc="-2+random(0)"
1573 Generate an amplitude modulated signal:
1575 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1579 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1581 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
1588 Null audio source, return unprocessed audio frames. It is mainly useful
1589 as a template and to be employed in analysis / debugging tools, or as
1590 the source for filters which ignore the input data (for example the sox
1593 This source accepts the following options:
1597 @item channel_layout, cl
1599 Specify the channel layout, and can be either an integer or a string
1600 representing a channel layout. The default value of @var{channel_layout}
1603 Check the channel_layout_map definition in
1604 @file{libavutil/channel_layout.c} for the mapping between strings and
1605 channel layout values.
1607 @item sample_rate, r
1608 Specify the sample rate, and defaults to 44100.
1611 Set the number of samples per requested frames.
1615 @subsection Examples
1619 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1621 anullsrc=r=48000:cl=4
1625 Do the same operation with a more obvious syntax:
1627 anullsrc=r=48000:cl=mono
1632 Buffer audio frames, and make them available to the filter chain.
1634 This source is not intended to be part of user-supplied graph descriptions but
1635 for insertion by calling programs through the interface defined in
1636 @file{libavfilter/buffersrc.h}.
1638 It accepts the following named parameters:
1642 Timebase which will be used for timestamps of submitted frames. It must be
1643 either a floating-point number or in @var{numerator}/@var{denominator} form.
1649 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1651 @item channel_layout
1652 Channel layout of the audio data, in the form that can be accepted by
1653 @code{av_get_channel_layout()}.
1656 All the parameters need to be explicitly defined.
1660 Synthesize a voice utterance using the libflite library.
1662 To enable compilation of this filter you need to configure FFmpeg with
1663 @code{--enable-libflite}.
1665 Note that the flite library is not thread-safe.
1667 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1670 The description of the accepted parameters follows.
1675 If set to 1, list the names of the available voices and exit
1676 immediately. Default value is 0.
1679 Set the maximum number of samples per frame. Default value is 512.
1682 Set the filename containing the text to speak.
1685 Set the text to speak.
1688 Set the voice to use for the speech synthesis. Default value is
1689 @code{kal}. See also the @var{list_voices} option.
1692 @subsection Examples
1696 Read from file @file{speech.txt}, and synthetize the text using the
1697 standard flite voice:
1699 flite=textfile=speech.txt
1703 Read the specified text selecting the @code{slt} voice:
1705 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1709 Input text to ffmpeg:
1711 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1715 Make @file{ffplay} speak the specified text, using @code{flite} and
1716 the @code{lavfi} device:
1718 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1722 For more information about libflite, check:
1723 @url{http://www.speech.cs.cmu.edu/flite/}
1727 Generate an audio signal made of a sine wave with amplitude 1/8.
1729 The audio signal is bit-exact.
1731 The filter accepts the following options:
1736 Set the carrier frequency. Default is 440 Hz.
1738 @item beep_factor, b
1739 Enable a periodic beep every second with frequency @var{beep_factor} times
1740 the carrier frequency. Default is 0, meaning the beep is disabled.
1742 @item sample_rate, s
1743 Specify the sample rate, default is 44100.
1746 Specify the duration of the generated audio stream.
1748 @item samples_per_frame
1749 Set the number of samples per output frame, default is 1024.
1752 @subsection Examples
1757 Generate a simple 440 Hz sine wave:
1763 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1767 sine=frequency=220:beep_factor=4:duration=5
1772 @c man end AUDIO SOURCES
1774 @chapter Audio Sinks
1775 @c man begin AUDIO SINKS
1777 Below is a description of the currently available audio sinks.
1779 @section abuffersink
1781 Buffer audio frames, and make them available to the end of filter chain.
1783 This sink is mainly intended for programmatic use, in particular
1784 through the interface defined in @file{libavfilter/buffersink.h}.
1786 It requires a pointer to an AVABufferSinkContext structure, which
1787 defines the incoming buffers' formats, to be passed as the opaque
1788 parameter to @code{avfilter_init_filter} for initialization.
1792 Null audio sink, do absolutely nothing with the input audio. It is
1793 mainly useful as a template and to be employed in analysis / debugging
1796 @section abuffersink
1797 This sink is intended for programmatic use. Frames that arrive on this sink can
1798 be retrieved by the calling program using the interface defined in
1799 @file{libavfilter/buffersink.h}.
1801 This filter accepts no parameters.
1803 @c man end AUDIO SINKS
1805 @chapter Video Filters
1806 @c man begin VIDEO FILTERS
1808 When you configure your FFmpeg build, you can disable any of the
1809 existing filters using @code{--disable-filters}.
1810 The configure output will show the video filters included in your
1813 Below is a description of the currently available video filters.
1815 @section alphaextract
1817 Extract the alpha component from the input as a grayscale video. This
1818 is especially useful with the @var{alphamerge} filter.
1822 Add or replace the alpha component of the primary input with the
1823 grayscale value of a second input. This is intended for use with
1824 @var{alphaextract} to allow the transmission or storage of frame
1825 sequences that have alpha in a format that doesn't support an alpha
1828 For example, to reconstruct full frames from a normal YUV-encoded video
1829 and a separate video created with @var{alphaextract}, you might use:
1831 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1834 Since this filter is designed for reconstruction, it operates on frame
1835 sequences without considering timestamps, and terminates when either
1836 input reaches end of stream. This will cause problems if your encoding
1837 pipeline drops frames. If you're trying to apply an image as an
1838 overlay to a video stream, consider the @var{overlay} filter instead.
1842 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1843 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1844 Substation Alpha) subtitles files.
1848 Compute the bounding box for the non-black pixels in the input frame
1851 This filter computes the bounding box containing all the pixels with a
1852 luminance value greater than the minimum allowed value.
1853 The parameters describing the bounding box are printed on the filter
1856 @section blackdetect
1858 Detect video intervals that are (almost) completely black. Can be
1859 useful to detect chapter transitions, commercials, or invalid
1860 recordings. Output lines contains the time for the start, end and
1861 duration of the detected black interval expressed in seconds.
1863 In order to display the output lines, you need to set the loglevel at
1864 least to the AV_LOG_INFO value.
1866 The filter accepts the following options:
1869 @item black_min_duration, d
1870 Set the minimum detected black duration expressed in seconds. It must
1871 be a non-negative floating point number.
1873 Default value is 2.0.
1875 @item picture_black_ratio_th, pic_th
1876 Set the threshold for considering a picture "black".
1877 Express the minimum value for the ratio:
1879 @var{nb_black_pixels} / @var{nb_pixels}
1882 for which a picture is considered black.
1883 Default value is 0.98.
1885 @item pixel_black_th, pix_th
1886 Set the threshold for considering a pixel "black".
1888 The threshold expresses the maximum pixel luminance value for which a
1889 pixel is considered "black". The provided value is scaled according to
1890 the following equation:
1892 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1895 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1896 the input video format, the range is [0-255] for YUV full-range
1897 formats and [16-235] for YUV non full-range formats.
1899 Default value is 0.10.
1902 The following example sets the maximum pixel threshold to the minimum
1903 value, and detects only black intervals of 2 or more seconds:
1905 blackdetect=d=2:pix_th=0.00
1910 Detect frames that are (almost) completely black. Can be useful to
1911 detect chapter transitions or commercials. Output lines consist of
1912 the frame number of the detected frame, the percentage of blackness,
1913 the position in the file if known or -1 and the timestamp in seconds.
1915 In order to display the output lines, you need to set the loglevel at
1916 least to the AV_LOG_INFO value.
1918 The filter accepts parameters as a list of @var{key}=@var{value}
1919 pairs, separated by ":". If the key of the first options is omitted,
1920 the arguments are interpreted according to the syntax
1921 blackframe[=@var{amount}[:@var{threshold}]].
1923 The filter accepts the following options:
1928 The percentage of the pixels that have to be below the threshold, defaults to
1932 Threshold below which a pixel value is considered black, defaults to 32.
1938 Blend two video frames into each other.
1940 It takes two input streams and outputs one stream, the first input is the
1941 "top" layer and second input is "bottom" layer.
1942 Output terminates when shortest input terminates.
1944 A description of the accepted options follows.
1952 Set blend mode for specific pixel component or all pixel components in case
1953 of @var{all_mode}. Default value is @code{normal}.
1955 Available values for component modes are:
1988 Set blend opacity for specific pixel component or all pixel components in case
1989 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1996 Set blend expression for specific pixel component or all pixel components in case
1997 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1999 The expressions can use the following variables:
2003 The sequential number of the filtered frame, starting from @code{0}.
2007 the coordinates of the current sample
2011 the width and height of currently filtered plane
2015 Width and height scale depending on the currently filtered plane. It is the
2016 ratio between the corresponding luma plane number of pixels and the current
2017 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2018 @code{0.5,0.5} for chroma planes.
2021 Time of the current frame, expressed in seconds.
2024 Value of pixel component at current location for first video frame (top layer).
2027 Value of pixel component at current location for second video frame (bottom layer).
2031 @subsection Examples
2035 Apply transition from bottom layer to top layer in first 10 seconds:
2037 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2041 Apply 1x1 checkerboard effect:
2043 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2049 Apply boxblur algorithm to the input video.
2051 The filter accepts parameters as a list of @var{key}=@var{value}
2052 pairs, separated by ":". If the key of the first options is omitted,
2053 the arguments are interpreted according to the syntax
2054 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2056 This filter accepts the following options:
2069 A description of the accepted options follows.
2072 @item luma_radius, lr
2073 @item chroma_radius, cr
2074 @item alpha_radius, ar
2075 Set an expression for the box radius in pixels used for blurring the
2076 corresponding input plane.
2078 The radius value must be a non-negative number, and must not be
2079 greater than the value of the expression @code{min(w,h)/2} for the
2080 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2083 Default value for @option{luma_radius} is "2". If not specified,
2084 @option{chroma_radius} and @option{alpha_radius} default to the
2085 corresponding value set for @option{luma_radius}.
2087 The expressions can contain the following constants:
2090 the input width and height in pixels
2093 the input chroma image width and height in pixels
2096 horizontal and vertical chroma subsample values. For example for the
2097 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2100 @item luma_power, lp
2101 @item chroma_power, cp
2102 @item alpha_power, ap
2103 Specify how many times the boxblur filter is applied to the
2104 corresponding plane.
2106 Default value for @option{luma_power} is 2. If not specified,
2107 @option{chroma_power} and @option{alpha_power} default to the
2108 corresponding value set for @option{luma_power}.
2110 A value of 0 will disable the effect.
2113 @subsection Examples
2117 Apply a boxblur filter with luma, chroma, and alpha radius
2120 boxblur=luma_radius=2:luma_power=1
2125 Set luma radius to 2, alpha and chroma radius to 0:
2127 boxblur=2:1:cr=0:ar=0
2131 Set luma and chroma radius to a fraction of the video dimension:
2133 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2137 @section colormatrix
2139 Convert color matrix.
2141 The filter accepts the following options:
2146 Specify the source and destination color matrix. Both values must be
2149 The accepted values are:
2165 For example to convert from BT.601 to SMPTE-240M, use the command:
2167 colormatrix=bt601:smpte240m
2172 Copy the input source unchanged to the output. Mainly useful for
2177 Crop the input video to given dimensions.
2179 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2180 separated by ':'. If the key of the first options is omitted, the
2181 arguments are interpreted according to the syntax
2182 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2184 A description of the accepted options follows:
2187 Width of the output video. It defaults to @code{iw}.
2188 This expression is evaluated only once during the filter
2192 Height of the output video. It defaults to @code{ih}.
2193 This expression is evaluated only once during the filter
2197 Horizontal position, in the input video, of the left edge of the output video.
2198 It defaults to @code{(in_w-out_w)/2}.
2199 This expression is evaluated per-frame.
2202 Vertical position, in the input video, of the top edge of the output video.
2203 It defaults to @code{(in_h-out_h)/2}.
2204 This expression is evaluated per-frame.
2207 If set to 1 will force the output display aspect ratio
2208 to be the same of the input, by changing the output sample aspect
2209 ratio. It defaults to 0.
2212 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2213 expressions containing the following constants:
2217 the computed values for @var{x} and @var{y}. They are evaluated for
2221 the input width and height
2224 same as @var{in_w} and @var{in_h}
2227 the output (cropped) width and height
2230 same as @var{out_w} and @var{out_h}
2233 same as @var{iw} / @var{ih}
2236 input sample aspect ratio
2239 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2242 horizontal and vertical chroma subsample values. For example for the
2243 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2246 the number of input frame, starting from 0
2249 timestamp expressed in seconds, NAN if the input timestamp is unknown
2253 The expression for @var{out_w} may depend on the value of @var{out_h},
2254 and the expression for @var{out_h} may depend on @var{out_w}, but they
2255 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2256 evaluated after @var{out_w} and @var{out_h}.
2258 The @var{x} and @var{y} parameters specify the expressions for the
2259 position of the top-left corner of the output (non-cropped) area. They
2260 are evaluated for each frame. If the evaluated value is not valid, it
2261 is approximated to the nearest valid value.
2263 The expression for @var{x} may depend on @var{y}, and the expression
2264 for @var{y} may depend on @var{x}.
2266 @subsection Examples
2270 Crop area with size 100x100 at position (12,34).
2275 Using named options, the example above becomes:
2277 crop=w=100:h=100:x=12:y=34
2281 Crop the central input area with size 100x100:
2287 Crop the central input area with size 2/3 of the input video:
2289 crop=2/3*in_w:2/3*in_h
2293 Crop the input video central square:
2300 Delimit the rectangle with the top-left corner placed at position
2301 100:100 and the right-bottom corner corresponding to the right-bottom
2302 corner of the input image:
2304 crop=in_w-100:in_h-100:100:100
2308 Crop 10 pixels from the left and right borders, and 20 pixels from
2309 the top and bottom borders
2311 crop=in_w-2*10:in_h-2*20
2315 Keep only the bottom right quarter of the input image:
2317 crop=in_w/2:in_h/2:in_w/2:in_h/2
2321 Crop height for getting Greek harmony:
2323 crop=in_w:1/PHI*in_w
2327 Appply trembling effect:
2329 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)
2333 Apply erratic camera effect depending on timestamp:
2335 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)"
2339 Set x depending on the value of y:
2341 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2347 Auto-detect crop size.
2349 Calculate necessary cropping parameters and prints the recommended
2350 parameters through the logging system. The detected dimensions
2351 correspond to the non-black area of the input video.
2353 The filter accepts parameters as a list of @var{key}=@var{value}
2354 pairs, separated by ":". If the key of the first options is omitted,
2355 the arguments are interpreted according to the syntax
2356 [@option{limit}[:@option{round}[:@option{reset}]]].
2358 A description of the accepted options follows.
2363 Set higher black value threshold, which can be optionally specified
2364 from nothing (0) to everything (255). An intensity value greater
2365 to the set value is considered non-black. Default value is 24.
2368 Set the value for which the width/height should be divisible by. The
2369 offset is automatically adjusted to center the video. Use 2 to get
2370 only even dimensions (needed for 4:2:2 video). 16 is best when
2371 encoding to most video codecs. Default value is 16.
2374 Set the counter that determines after how many frames cropdetect will
2375 reset the previously detected largest video area and start over to
2376 detect the current optimal crop area. Default value is 0.
2378 This can be useful when channel logos distort the video area. 0
2379 indicates never reset and return the largest area encountered during
2385 Apply color adjustments using curves.
2387 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2388 component (red, green and blue) has its values defined by @var{N} key points
2389 tied from each other using a smooth curve. The x-axis represents the pixel
2390 values from the input frame, and the y-axis the new pixel values to be set for
2393 By default, a component curve is defined by the two points @var{(0;0)} and
2394 @var{(1;1)}. This creates a straight line where each original pixel value is
2395 "adjusted" to its own value, which means no change to the image.
2397 The filter allows you to redefine these two points and add some more. A new
2398 curve (using a natural cubic spline interpolation) will be define to pass
2399 smoothly through all these new coordinates. The new defined points needs to be
2400 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2401 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2402 the vector spaces, the values will be clipped accordingly.
2404 If there is no key point defined in @code{x=0}, the filter will automatically
2405 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2406 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2408 The filter accepts the following options:
2412 Select one of the available color presets. This option can be used in addition
2413 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2414 options takes priority on the preset values.
2415 Available presets are:
2418 @item color_negative
2421 @item increase_contrast
2423 @item linear_contrast
2424 @item medium_contrast
2426 @item strong_contrast
2429 Default is @code{none}.
2431 Set the key points for the red component.
2433 Set the key points for the green component.
2435 Set the key points for the blue component.
2437 Set the key points for all components.
2438 Can be used in addition to the other key points component
2439 options. In this case, the unset component(s) will fallback on this
2440 @option{all} setting.
2443 To avoid some filtergraph syntax conflicts, each key points list need to be
2444 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2446 @subsection Examples
2450 Increase slightly the middle level of blue:
2452 curves=blue='0.5/0.58'
2458 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2460 Here we obtain the following coordinates for each components:
2463 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2465 @code{(0;0) (0.50;0.48) (1;1)}
2467 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2471 The previous example can also be achieved with the associated built-in preset:
2473 curves=preset=vintage
2485 Drop frames that do not differ greatly from the previous frame in
2486 order to reduce frame rate.
2488 The main use of this filter is for very-low-bitrate encoding
2489 (e.g. streaming over dialup modem), but it could in theory be used for
2490 fixing movies that were inverse-telecined incorrectly.
2492 A description of the accepted options follows.
2496 Set the maximum number of consecutive frames which can be dropped (if
2497 positive), or the minimum interval between dropped frames (if
2498 negative). If the value is 0, the frame is dropped unregarding the
2499 number of previous sequentially dropped frames.
2506 Set the dropping threshold values.
2508 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2509 represent actual pixel value differences, so a threshold of 64
2510 corresponds to 1 unit of difference for each pixel, or the same spread
2511 out differently over the block.
2513 A frame is a candidate for dropping if no 8x8 blocks differ by more
2514 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2515 meaning the whole image) differ by more than a threshold of @option{lo}.
2517 Default value for @option{hi} is 64*12, default value for @option{lo} is
2518 64*5, and default value for @option{frac} is 0.33.
2523 Suppress a TV station logo by a simple interpolation of the surrounding
2524 pixels. Just set a rectangle covering the logo and watch it disappear
2525 (and sometimes something even uglier appear - your mileage may vary).
2527 This filter accepts the following options:
2531 Specify the top left corner coordinates of the logo. They must be
2535 Specify the width and height of the logo to clear. They must be
2539 Specify the thickness of the fuzzy edge of the rectangle (added to
2540 @var{w} and @var{h}). The default value is 4.
2543 When set to 1, a green rectangle is drawn on the screen to simplify
2544 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2545 @var{band} is set to 4. The default value is 0.
2549 @subsection Examples
2553 Set a rectangle covering the area with top left corner coordinates 0,0
2554 and size 100x77, setting a band of size 10:
2556 delogo=x=0:y=0:w=100:h=77:band=10
2563 Attempt to fix small changes in horizontal and/or vertical shift. This
2564 filter helps remove camera shake from hand-holding a camera, bumping a
2565 tripod, moving on a vehicle, etc.
2567 The filter accepts the following options:
2575 Specify a rectangular area where to limit the search for motion
2577 If desired the search for motion vectors can be limited to a
2578 rectangular area of the frame defined by its top left corner, width
2579 and height. These parameters have the same meaning as the drawbox
2580 filter which can be used to visualise the position of the bounding
2583 This is useful when simultaneous movement of subjects within the frame
2584 might be confused for camera motion by the motion vector search.
2586 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2587 then the full frame is used. This allows later options to be set
2588 without specifying the bounding box for the motion vector search.
2590 Default - search the whole frame.
2594 Specify the maximum extent of movement in x and y directions in the
2595 range 0-64 pixels. Default 16.
2598 Specify how to generate pixels to fill blanks at the edge of the
2599 frame. Available values are:
2602 Fill zeroes at blank locations
2604 Original image at blank locations
2606 Extruded edge value at blank locations
2608 Mirrored edge at blank locations
2610 Default value is @samp{mirror}.
2613 Specify the blocksize to use for motion search. Range 4-128 pixels,
2617 Specify the contrast threshold for blocks. Only blocks with more than
2618 the specified contrast (difference between darkest and lightest
2619 pixels) will be considered. Range 1-255, default 125.
2622 Specify the search strategy. Available values are:
2625 Set exhaustive search
2627 Set less exhaustive search.
2629 Default value is @samp{exhaustive}.
2632 If set then a detailed log of the motion search is written to the
2636 If set to 1, specify using OpenCL capabilities, only available if
2637 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2643 Draw a colored box on the input image.
2645 This filter accepts the following options:
2649 Specify the top left corner coordinates of the box. Default to 0.
2653 Specify the width and height of the box, if 0 they are interpreted as
2654 the input width and height. Default to 0.
2657 Specify the color of the box to write, it can be the name of a color
2658 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2659 value @code{invert} is used, the box edge color is the same as the
2660 video with inverted luma.
2663 Set the thickness of the box edge. Default value is @code{4}.
2666 @subsection Examples
2670 Draw a black box around the edge of the input image:
2676 Draw a box with color red and an opacity of 50%:
2678 drawbox=10:20:200:60:red@@0.5
2681 The previous example can be specified as:
2683 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2687 Fill the box with pink color:
2689 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2696 Draw text string or text from specified file on top of video using the
2697 libfreetype library.
2699 To enable compilation of this filter you need to configure FFmpeg with
2700 @code{--enable-libfreetype}.
2704 The description of the accepted parameters follows.
2709 Used to draw a box around text using background color.
2710 Value should be either 1 (enable) or 0 (disable).
2711 The default value of @var{box} is 0.
2714 The color to be used for drawing box around text.
2715 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2716 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2717 The default value of @var{boxcolor} is "white".
2720 Set an expression which specifies if the text should be drawn. If the
2721 expression evaluates to 0, the text is not drawn. This is useful for
2722 specifying that the text should be drawn only when specific conditions
2725 Default value is "1".
2727 See below for the list of accepted constants and functions.
2730 Select how the @var{text} is expanded. Can be either @code{none},
2731 @code{strftime} (deprecated) or
2732 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2736 If true, check and fix text coords to avoid clipping.
2739 The color to be used for drawing fonts.
2740 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2741 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2742 The default value of @var{fontcolor} is "black".
2745 The font file to be used for drawing text. Path must be included.
2746 This parameter is mandatory.
2749 The font size to be used for drawing text.
2750 The default value of @var{fontsize} is 16.
2753 Flags to be used for loading the fonts.
2755 The flags map the corresponding flags supported by libfreetype, and are
2756 a combination of the following values:
2763 @item vertical_layout
2764 @item force_autohint
2767 @item ignore_global_advance_width
2769 @item ignore_transform
2776 Default value is "render".
2778 For more information consult the documentation for the FT_LOAD_*
2782 The color to be used for drawing a shadow behind the drawn text. It
2783 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2784 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2785 The default value of @var{shadowcolor} is "black".
2787 @item shadowx, shadowy
2788 The x and y offsets for the text shadow position with respect to the
2789 position of the text. They can be either positive or negative
2790 values. Default value for both is "0".
2793 The size in number of spaces to use for rendering the tab.
2797 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2798 format. It can be used with or without text parameter. @var{timecode_rate}
2799 option must be specified.
2801 @item timecode_rate, rate, r
2802 Set the timecode frame rate (timecode only).
2805 The text string to be drawn. The text must be a sequence of UTF-8
2807 This parameter is mandatory if no file is specified with the parameter
2811 A text file containing text to be drawn. The text must be a sequence
2812 of UTF-8 encoded characters.
2814 This parameter is mandatory if no text string is specified with the
2815 parameter @var{text}.
2817 If both @var{text} and @var{textfile} are specified, an error is thrown.
2820 If set to 1, the @var{textfile} will be reloaded before each frame.
2821 Be sure to update it atomically, or it may be read partially, or even fail.
2824 The expressions which specify the offsets where text will be drawn
2825 within the video frame. They are relative to the top/left border of the
2828 The default value of @var{x} and @var{y} is "0".
2830 See below for the list of accepted constants and functions.
2833 The parameters for @var{x} and @var{y} are expressions containing the
2834 following constants and functions:
2838 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2841 horizontal and vertical chroma subsample values. For example for the
2842 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2845 the height of each text line
2853 @item max_glyph_a, ascent
2854 the maximum distance from the baseline to the highest/upper grid
2855 coordinate used to place a glyph outline point, for all the rendered
2857 It is a positive value, due to the grid's orientation with the Y axis
2860 @item max_glyph_d, descent
2861 the maximum distance from the baseline to the lowest grid coordinate
2862 used to place a glyph outline point, for all the rendered glyphs.
2863 This is a negative value, due to the grid's orientation, with the Y axis
2867 maximum glyph height, that is the maximum height for all the glyphs
2868 contained in the rendered text, it is equivalent to @var{ascent} -
2872 maximum glyph width, that is the maximum width for all the glyphs
2873 contained in the rendered text
2876 the number of input frame, starting from 0
2878 @item rand(min, max)
2879 return a random number included between @var{min} and @var{max}
2882 input sample aspect ratio
2885 timestamp expressed in seconds, NAN if the input timestamp is unknown
2888 the height of the rendered text
2891 the width of the rendered text
2894 the x and y offset coordinates where the text is drawn.
2896 These parameters allow the @var{x} and @var{y} expressions to refer
2897 each other, so you can for example specify @code{y=x/dar}.
2900 If libavfilter was built with @code{--enable-fontconfig}, then
2901 @option{fontfile} can be a fontconfig pattern or omitted.
2903 @anchor{drawtext_expansion}
2904 @subsection Text expansion
2906 If @option{expansion} is set to @code{strftime},
2907 the filter recognizes strftime() sequences in the provided text and
2908 expands them accordingly. Check the documentation of strftime(). This
2909 feature is deprecated.
2911 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2913 If @option{expansion} is set to @code{normal} (which is the default),
2914 the following expansion mechanism is used.
2916 The backslash character '\', followed by any character, always expands to
2917 the second character.
2919 Sequence of the form @code{%@{...@}} are expanded. The text between the
2920 braces is a function name, possibly followed by arguments separated by ':'.
2921 If the arguments contain special characters or delimiters (':' or '@}'),
2922 they should be escaped.
2924 Note that they probably must also be escaped as the value for the
2925 @option{text} option in the filter argument string and as the filter
2926 argument in the filtergraph description, and possibly also for the shell,
2927 that makes up to four levels of escaping; using a text file avoids these
2930 The following functions are available:
2935 The expression evaluation result.
2937 It must take one argument specifying the expression to be evaluated,
2938 which accepts the same constants and functions as the @var{x} and
2939 @var{y} values. Note that not all constants should be used, for
2940 example the text size is not known when evaluating the expression, so
2941 the constants @var{text_w} and @var{text_h} will have an undefined
2945 The time at which the filter is running, expressed in UTC.
2946 It can accept an argument: a strftime() format string.
2949 The time at which the filter is running, expressed in the local time zone.
2950 It can accept an argument: a strftime() format string.
2953 The frame number, starting from 0.
2956 The timestamp of the current frame, in seconds, with microsecond accuracy.
2960 @subsection Examples
2964 Draw "Test Text" with font FreeSerif, using the default values for the
2965 optional parameters.
2968 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2972 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2973 and y=50 (counting from the top-left corner of the screen), text is
2974 yellow with a red box around it. Both the text and the box have an
2978 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2979 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2982 Note that the double quotes are not necessary if spaces are not used
2983 within the parameter list.
2986 Show the text at the center of the video frame:
2988 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2992 Show a text line sliding from right to left in the last row of the video
2993 frame. The file @file{LONG_LINE} is assumed to contain a single line
2996 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3000 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3002 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3006 Draw a single green letter "g", at the center of the input video.
3007 The glyph baseline is placed at half screen height.
3009 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3013 Show text for 1 second every 3 seconds:
3015 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3019 Use fontconfig to set the font. Note that the colons need to be escaped.
3021 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3025 Print the date of a real-time encoding (see strftime(3)):
3027 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3032 For more information about libfreetype, check:
3033 @url{http://www.freetype.org/}.
3035 For more information about fontconfig, check:
3036 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3040 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3042 The filter accepts the following options:
3046 Set low and high threshold values used by the Canny thresholding
3049 The high threshold selects the "strong" edge pixels, which are then
3050 connected through 8-connectivity with the "weak" edge pixels selected
3051 by the low threshold.
3053 @var{low} and @var{high} threshold values must be choosen in the range
3054 [0,1], and @var{low} should be lesser or equal to @var{high}.
3056 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3062 edgedetect=low=0.1:high=0.4
3067 Apply fade-in/out effect to input video.
3069 This filter accepts the following options:
3073 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3075 Default is @code{in}.
3077 @item start_frame, s
3078 Specify the number of the start frame for starting to apply the fade
3079 effect. Default is 0.
3082 The number of frames for which the fade effect has to last. At the end of the
3083 fade-in effect the output video will have the same intensity as the input video,
3084 at the end of the fade-out transition the output video will be completely black.
3088 If set to 1, fade only alpha channel, if one exists on the input.
3092 @subsection Examples
3096 Fade in first 30 frames of video:
3101 The command above is equivalent to:
3107 Fade out last 45 frames of a 200-frame video:
3110 fade=type=out:start_frame=155:nb_frames=45
3114 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3116 fade=in:0:25, fade=out:975:25
3120 Make first 5 frames black, then fade in from frame 5-24:
3126 Fade in alpha over first 25 frames of video:
3128 fade=in:0:25:alpha=1
3134 Extract a single field from an interlaced image using stride
3135 arithmetic to avoid wasting CPU time. The output frames are marked as
3138 The filter accepts the following options:
3142 Specify whether to extract the top (if the value is @code{0} or
3143 @code{top}) or the bottom field (if the value is @code{1} or
3149 Transform the field order of the input video.
3151 This filter accepts the following options:
3156 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3157 for bottom field first.
3160 Default value is @samp{tff}.
3162 Transformation is achieved by shifting the picture content up or down
3163 by one line, and filling the remaining line with appropriate picture content.
3164 This method is consistent with most broadcast field order converters.
3166 If the input video is not flagged as being interlaced, or it is already
3167 flagged as being of the required output field order then this filter does
3168 not alter the incoming video.
3170 This filter is very useful when converting to or from PAL DV material,
3171 which is bottom field first.
3175 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3180 Buffer input images and send them when they are requested.
3182 This filter is mainly useful when auto-inserted by the libavfilter
3185 The filter does not take parameters.
3190 Convert the input video to one of the specified pixel formats.
3191 Libavfilter will try to pick one that is supported for the input to
3194 This filter accepts the following parameters:
3198 A '|'-separated list of pixel format names, for example
3199 "pix_fmts=yuv420p|monow|rgb24".
3203 @subsection Examples
3207 Convert the input video to the format @var{yuv420p}
3209 format=pix_fmts=yuv420p
3212 Convert the input video to any of the formats in the list
3214 format=pix_fmts=yuv420p|yuv444p|yuv410p
3220 Convert the video to specified constant frame rate by duplicating or dropping
3221 frames as necessary.
3223 This filter accepts the following named parameters:
3227 Desired output frame rate. The default is @code{25}.
3232 Possible values are:
3235 zero round towards 0
3239 round towards -infinity
3241 round towards +infinity
3245 The default is @code{near}.
3249 Alternatively, the options can be specified as a flat string:
3250 @var{fps}[:@var{round}].
3252 See also the @ref{setpts} filter.
3256 Select one frame every N-th frame.
3258 This filter accepts the following option:
3261 Select frame after every @code{step} frames.
3262 Allowed values are positive integers higher than 0. Default value is @code{1}.
3268 Apply a frei0r effect to the input video.
3270 To enable compilation of this filter you need to install the frei0r
3271 header and configure FFmpeg with @code{--enable-frei0r}.
3273 This filter accepts the following options:
3278 The name to the frei0r effect to load. If the environment variable
3279 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3280 directories specified by the colon separated list in @env{FREIOR_PATH},
3281 otherwise in the standard frei0r paths, which are in this order:
3282 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3283 @file{/usr/lib/frei0r-1/}.
3286 A '|'-separated list of parameters to pass to the frei0r effect.
3290 A frei0r effect parameter can be a boolean (whose values are specified
3291 with "y" and "n"), a double, a color (specified by the syntax
3292 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3293 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3294 description), a position (specified by the syntax @var{X}/@var{Y},
3295 @var{X} and @var{Y} being float numbers) and a string.
3297 The number and kind of parameters depend on the loaded effect. If an
3298 effect parameter is not specified the default value is set.
3300 @subsection Examples
3304 Apply the distort0r effect, set the first two double parameters:
3306 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3310 Apply the colordistance effect, take a color as first parameter:
3312 frei0r=colordistance:0.2/0.3/0.4
3313 frei0r=colordistance:violet
3314 frei0r=colordistance:0x112233
3318 Apply the perspective effect, specify the top left and top right image
3321 frei0r=perspective:0.2/0.2|0.8/0.2
3325 For more information see:
3326 @url{http://frei0r.dyne.org}
3330 The filter accepts the following options:
3334 the luminance expression
3336 the chrominance blue expression
3338 the chrominance red expression
3340 the alpha expression
3343 If one of the chrominance expression is not defined, it falls back on the other
3344 one. If no alpha expression is specified it will evaluate to opaque value.
3345 If none of chrominance expressions are
3346 specified, they will evaluate the luminance expression.
3348 The expressions can use the following variables and functions:
3352 The sequential number of the filtered frame, starting from @code{0}.
3356 The coordinates of the current sample.
3360 The width and height of the image.
3364 Width and height scale depending on the currently filtered plane. It is the
3365 ratio between the corresponding luma plane number of pixels and the current
3366 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3367 @code{0.5,0.5} for chroma planes.
3370 Time of the current frame, expressed in seconds.
3373 Return the value of the pixel at location (@var{x},@var{y}) of the current
3377 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3381 Return the value of the pixel at location (@var{x},@var{y}) of the
3382 blue-difference chroma plane. Returns 0 if there is no such plane.
3385 Return the value of the pixel at location (@var{x},@var{y}) of the
3386 red-difference chroma plane. Returns 0 if there is no such plane.
3389 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3390 plane. Returns 0 if there is no such plane.
3393 For functions, if @var{x} and @var{y} are outside the area, the value will be
3394 automatically clipped to the closer edge.
3396 @subsection Examples
3400 Flip the image horizontally:
3406 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3407 wavelength of 100 pixels:
3409 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3413 Generate a fancy enigmatic moving light:
3415 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
3421 Fix the banding artifacts that are sometimes introduced into nearly flat
3422 regions by truncation to 8bit color depth.
3423 Interpolate the gradients that should go where the bands are, and
3426 This filter is designed for playback only. Do not use it prior to
3427 lossy compression, because compression tends to lose the dither and
3428 bring back the bands.
3430 This filter accepts the following options:
3435 The maximum amount by which the filter will change any one pixel. Also the
3436 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3437 64, default value is 1.2, out-of-range values will be clipped to the valid
3441 The neighborhood to fit the gradient to. A larger radius makes for smoother
3442 gradients, but also prevents the filter from modifying the pixels near detailed
3443 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3444 will be clipped to the valid range.
3448 Alternatively, the options can be specified as a flat string:
3449 @var{strength}[:@var{radius}]
3451 @subsection Examples
3455 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3461 Specify radius, omitting the strength (which will fall-back to the default
3471 Flip the input video horizontally.
3473 For example to horizontally flip the input video with @command{ffmpeg}:
3475 ffmpeg -i in.avi -vf "hflip" out.avi
3479 This filter applies a global color histogram equalization on a
3482 It can be used to correct video that has a compressed range of pixel
3483 intensities. The filter redistributes the pixel intensities to
3484 equalize their distribution across the intensity range. It may be
3485 viewed as an "automatically adjusting contrast filter". This filter is
3486 useful only for correcting degraded or poorly captured source
3489 The filter accepts the following options:
3493 Determine the amount of equalization to be applied. As the strength
3494 is reduced, the distribution of pixel intensities more-and-more
3495 approaches that of the input frame. The value must be a float number
3496 in the range [0,1] and defaults to 0.200.
3499 Set the maximum intensity that can generated and scale the output
3500 values appropriately. The strength should be set as desired and then
3501 the intensity can be limited if needed to avoid washing-out. The value
3502 must be a float number in the range [0,1] and defaults to 0.210.
3505 Set the antibanding level. If enabled the filter will randomly vary
3506 the luminance of output pixels by a small amount to avoid banding of
3507 the histogram. Possible values are @code{none}, @code{weak} or
3508 @code{strong}. It defaults to @code{none}.
3513 Compute and draw a color distribution histogram for the input video.
3515 The computed histogram is a representation of distribution of color components
3518 The filter accepts the following options:
3524 It accepts the following values:
3527 standard histogram that display color components distribution in an image.
3528 Displays color graph for each color component. Shows distribution
3529 of the Y, U, V, A or G, B, R components, depending on input format,
3530 in current frame. Bellow each graph is color component scale meter.
3533 chroma values in vectorscope, if brighter more such chroma values are
3534 distributed in an image.
3535 Displays chroma values (U/V color placement) in two dimensional graph
3536 (which is called a vectorscope). It can be used to read of the hue and
3537 saturation of the current frame. At a same time it is a histogram.
3538 The whiter a pixel in the vectorscope, the more pixels of the input frame
3539 correspond to that pixel (that is the more pixels have this chroma value).
3540 The V component is displayed on the horizontal (X) axis, with the leftmost
3541 side being V = 0 and the rightmost side being V = 255.
3542 The U component is displayed on the vertical (Y) axis, with the top
3543 representing U = 0 and the bottom representing U = 255.
3545 The position of a white pixel in the graph corresponds to the chroma value
3546 of a pixel of the input clip. So the graph can be used to read of the
3547 hue (color flavor) and the saturation (the dominance of the hue in the color).
3548 As the hue of a color changes, it moves around the square. At the center of
3549 the square, the saturation is zero, which means that the corresponding pixel
3550 has no color. If you increase the amount of a specific color, while leaving
3551 the other colors unchanged, the saturation increases, and you move towards
3552 the edge of the square.
3555 chroma values in vectorscope, similar as @code{color} but actual chroma values
3559 per row/column color component graph. In row mode graph in the left side represents
3560 color component value 0 and right side represents value = 255. In column mode top
3561 side represents color component value = 0 and bottom side represents value = 255.
3563 Default value is @code{levels}.
3566 Set height of level in @code{levels}. Default value is @code{200}.
3567 Allowed range is [50, 2048].
3570 Set height of color scale in @code{levels}. Default value is @code{12}.
3571 Allowed range is [0, 40].
3574 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3575 of same luminance values across input rows/columns are distributed.
3576 Default value is @code{10}. Allowed range is [1, 255].
3579 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3580 Default is @code{row}.
3583 Set display mode for @code{waveform} and @code{levels}.
3584 It accepts the following values:
3587 Display separate graph for the color components side by side in
3588 @code{row} waveform mode or one below other in @code{column} waveform mode
3589 for @code{waveform} histogram mode. For @code{levels} histogram mode
3590 per color component graphs are placed one bellow other.
3592 This display mode in @code{waveform} histogram mode makes it easy to spot
3593 color casts in the highlights and shadows of an image, by comparing the
3594 contours of the top and the bottom of each waveform.
3595 Since whites, grays, and blacks are characterized by
3596 exactly equal amounts of red, green, and blue, neutral areas of the
3597 picture should display three waveforms of roughly equal width/height.
3598 If not, the correction is easy to make by making adjustments to level the
3602 Presents information that's identical to that in the @code{parade}, except
3603 that the graphs representing color components are superimposed directly
3606 This display mode in @code{waveform} histogram mode can make it easier to spot
3607 the relative differences or similarities in overlapping areas of the color
3608 components that are supposed to be identical, such as neutral whites, grays,
3611 Default is @code{parade}.
3614 @subsection Examples
3619 Calculate and draw histogram:
3621 ffplay -i input -vf histogram
3628 High precision/quality 3d denoise filter. This filter aims to reduce
3629 image noise producing smooth images and making still images really
3630 still. It should enhance compressibility.
3632 It accepts the following optional parameters:
3636 a non-negative float number which specifies spatial luma strength,
3639 @item chroma_spatial
3640 a non-negative float number which specifies spatial chroma strength,
3641 defaults to 3.0*@var{luma_spatial}/4.0
3644 a float number which specifies luma temporal strength, defaults to
3645 6.0*@var{luma_spatial}/4.0
3648 a float number which specifies chroma temporal strength, defaults to
3649 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3654 Modify the hue and/or the saturation of the input.
3656 This filter accepts the following optional named options:
3660 Specify the hue angle as a number of degrees. It accepts a float
3661 number or an expression, and defaults to 0.0.
3664 Specify the hue angle as a number of radians. It accepts a float
3665 number or an expression, and defaults to 0.0.
3668 Specify the saturation in the [-10,10] range. It accepts a float number and
3672 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3673 following constants:
3677 frame count of the input frame starting from 0
3680 presentation timestamp of the input frame expressed in time base units
3683 frame rate of the input video, NAN if the input frame rate is unknown
3686 timestamp expressed in seconds, NAN if the input timestamp is unknown
3689 time base of the input video
3692 The options can also be set using the syntax: @var{hue}:@var{saturation}
3694 In this case @var{hue} is expressed in degrees.
3696 @subsection Examples
3700 Set the hue to 90 degrees and the saturation to 1.0:
3706 Same command but expressing the hue in radians:
3712 Same command without named options, hue must be expressed in degrees:
3718 Note that "h:s" syntax does not support expressions for the values of
3719 h and s, so the following example will issue an error:
3725 Rotate hue and make the saturation swing between 0
3726 and 2 over a period of 1 second:
3728 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3732 Apply a 3 seconds saturation fade-in effect starting at 0:
3737 The general fade-in expression can be written as:
3739 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3743 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3745 hue="s=max(0\, min(1\, (8-t)/3))"
3748 The general fade-out expression can be written as:
3750 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3755 @subsection Commands
3757 This filter supports the following command:
3760 Modify the hue and/or the saturation of the input video.
3761 The command accepts the same named options and syntax than when calling the
3762 filter from the command-line.
3764 If a parameter is omitted, it is kept at its current value.
3769 Detect video interlacing type.
3771 This filter tries to detect if the input is interlaced or progressive,
3772 top or bottom field first.
3774 The filter accepts the following options:
3778 Set interlacing threshold.
3780 Set progressive threshold.
3785 Deinterleave or interleave fields.
3787 This filter allows to process interlaced images fields without
3788 deinterlacing them. Deinterleaving splits the input frame into 2
3789 fields (so called half pictures). Odd lines are moved to the top
3790 half of the output image, even lines to the bottom half.
3791 You can process (filter) them independently and then re-interleave them.
3793 The filter accepts the following options:
3797 @item chroma_mode, s
3799 Available values for @var{luma_mode}, @var{chroma_mode} and
3800 @var{alpha_mode} are:
3806 @item deinterleave, d
3807 Deinterleave fields, placing one above the other.
3810 Interleave fields. Reverse the effect of deinterleaving.
3812 Default value is @code{none}.
3815 @item chroma_swap, cs
3816 @item alpha_swap, as
3817 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3822 Deinterlace input video by applying Donald Graft's adaptive kernel
3823 deinterling. Work on interlaced parts of a video to produce
3826 The description of the accepted parameters follows.
3830 Set the threshold which affects the filter's tolerance when
3831 determining if a pixel line must be processed. It must be an integer
3832 in the range [0,255] and defaults to 10. A value of 0 will result in
3833 applying the process on every pixels.
3836 Paint pixels exceeding the threshold value to white if set to 1.
3840 Set the fields order. Swap fields if set to 1, leave fields alone if
3844 Enable additional sharpening if set to 1. Default is 0.
3847 Enable twoway sharpening if set to 1. Default is 0.
3850 @subsection Examples
3854 Apply default values:
3856 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3860 Enable additional sharpening:
3866 Paint processed pixels in white:
3872 @section lut, lutrgb, lutyuv
3874 Compute a look-up table for binding each pixel component input value
3875 to an output value, and apply it to input video.
3877 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3878 to an RGB input video.
3880 These filters accept the following options:
3883 set first pixel component expression
3885 set second pixel component expression
3887 set third pixel component expression
3889 set fourth pixel component expression, corresponds to the alpha component
3892 set red component expression
3894 set green component expression
3896 set blue component expression
3898 alpha component expression
3901 set Y/luminance component expression
3903 set U/Cb component expression
3905 set V/Cr component expression
3908 Each of them specifies the expression to use for computing the lookup table for
3909 the corresponding pixel component values.
3911 The exact component associated to each of the @var{c*} options depends on the
3914 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3915 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3917 The expressions can contain the following constants and functions:
3921 the input width and height
3924 input value for the pixel component
3927 the input value clipped in the @var{minval}-@var{maxval} range
3930 maximum value for the pixel component
3933 minimum value for the pixel component
3936 the negated value for the pixel component value clipped in the
3937 @var{minval}-@var{maxval} range , it corresponds to the expression
3938 "maxval-clipval+minval"
3941 the computed value in @var{val} clipped in the
3942 @var{minval}-@var{maxval} range
3944 @item gammaval(gamma)
3945 the computed gamma correction value of the pixel component value
3946 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3948 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3952 All expressions default to "val".
3954 @subsection Examples
3960 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3961 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3964 The above is the same as:
3966 lutrgb="r=negval:g=negval:b=negval"
3967 lutyuv="y=negval:u=negval:v=negval"
3977 Remove chroma components, turns the video into a graytone image:
3979 lutyuv="u=128:v=128"
3983 Apply a luma burning effect:
3989 Remove green and blue components:
3995 Set a constant alpha channel value on input:
3997 format=rgba,lutrgb=a="maxval-minval/2"
4001 Correct luminance gamma by a 0.5 factor:
4003 lutyuv=y=gammaval(0.5)
4007 Discard least significant bits of luma:
4009 lutyuv=y='bitand(val, 128+64+32)'
4015 Apply an MPlayer filter to the input video.
4017 This filter provides a wrapper around most of the filters of
4020 This wrapper is considered experimental. Some of the wrapped filters
4021 may not work properly and we may drop support for them, as they will
4022 be implemented natively into FFmpeg. Thus you should avoid
4023 depending on them when writing portable scripts.
4025 The filters accepts the parameters:
4026 @var{filter_name}[:=]@var{filter_params}
4028 @var{filter_name} is the name of a supported MPlayer filter,
4029 @var{filter_params} is a string containing the parameters accepted by
4032 The list of the currently supported filters follows:
4059 The parameter syntax and behavior for the listed filters are the same
4060 of the corresponding MPlayer filters. For detailed instructions check
4061 the "VIDEO FILTERS" section in the MPlayer manual.
4063 @subsection Examples
4067 Adjust gamma, brightness, contrast:
4073 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4079 This filter accepts an integer in input, if non-zero it negates the
4080 alpha component (if available). The default value in input is 0.
4084 Force libavfilter not to use any of the specified pixel formats for the
4085 input to the next filter.
4087 This filter accepts the following parameters:
4091 A '|'-separated list of pixel format names, for example
4092 "pix_fmts=yuv420p|monow|rgb24".
4096 @subsection Examples
4100 Force libavfilter to use a format different from @var{yuv420p} for the
4101 input to the vflip filter:
4103 noformat=pix_fmts=yuv420p,vflip
4107 Convert the input video to any of the formats not contained in the list:
4109 noformat=yuv420p|yuv444p|yuv410p
4115 Add noise on video input frame.
4117 The filter accepts the following options:
4125 Set noise seed for specific pixel component or all pixel components in case
4126 of @var{all_seed}. Default value is @code{123457}.
4128 @item all_strength, alls
4129 @item c0_strength, c0s
4130 @item c1_strength, c1s
4131 @item c2_strength, c2s
4132 @item c3_strength, c3s
4133 Set noise strength for specific pixel component or all pixel components in case
4134 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4136 @item all_flags, allf
4141 Set pixel component flags or set flags for all components if @var{all_flags}.
4142 Available values for component flags are:
4145 averaged temporal noise (smoother)
4147 mix random noise with a (semi)regular pattern
4149 higher quality (slightly better looking, slightly slower)
4151 temporal noise (noise pattern changes between frames)
4153 uniform noise (gaussian otherwise)
4157 @subsection Examples
4159 Add temporal and uniform noise to input video:
4161 noise=alls=20:allf=t+u
4166 Pass the video source unchanged to the output.
4170 Apply video transform using libopencv.
4172 To enable this filter install libopencv library and headers and
4173 configure FFmpeg with @code{--enable-libopencv}.
4175 This filter accepts the following parameters:
4180 The name of the libopencv filter to apply.
4183 The parameters to pass to the libopencv filter. If not specified the default
4188 Refer to the official libopencv documentation for more precise
4190 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4192 Follows the list of supported libopencv filters.
4197 Dilate an image by using a specific structuring element.
4198 This filter corresponds to the libopencv function @code{cvDilate}.
4200 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4202 @var{struct_el} represents a structuring element, and has the syntax:
4203 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4205 @var{cols} and @var{rows} represent the number of columns and rows of
4206 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4207 point, and @var{shape} the shape for the structuring element, and
4208 can be one of the values "rect", "cross", "ellipse", "custom".
4210 If the value for @var{shape} is "custom", it must be followed by a
4211 string of the form "=@var{filename}". The file with name
4212 @var{filename} is assumed to represent a binary image, with each
4213 printable character corresponding to a bright pixel. When a custom
4214 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4215 or columns and rows of the read file are assumed instead.
4217 The default value for @var{struct_el} is "3x3+0x0/rect".
4219 @var{nb_iterations} specifies the number of times the transform is
4220 applied to the image, and defaults to 1.
4222 Follow some example:
4224 # use the default values
4227 # dilate using a structuring element with a 5x5 cross, iterate two times
4228 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4230 # read the shape from the file diamond.shape, iterate two times
4231 # the file diamond.shape may contain a pattern of characters like this:
4237 # the specified cols and rows are ignored (but not the anchor point coordinates)
4238 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4243 Erode an image by using a specific structuring element.
4244 This filter corresponds to the libopencv function @code{cvErode}.
4246 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4247 with the same syntax and semantics as the @ref{dilate} filter.
4251 Smooth the input video.
4253 The filter takes the following parameters:
4254 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4256 @var{type} is the type of smooth filter to apply, and can be one of
4257 the following values: "blur", "blur_no_scale", "median", "gaussian",
4258 "bilateral". The default value is "gaussian".
4260 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4261 parameters whose meanings depend on smooth type. @var{param1} and
4262 @var{param2} accept integer positive values or 0, @var{param3} and
4263 @var{param4} accept float values.
4265 The default value for @var{param1} is 3, the default value for the
4266 other parameters is 0.
4268 These parameters correspond to the parameters assigned to the
4269 libopencv function @code{cvSmooth}.
4274 Overlay one video on top of another.
4276 It takes two inputs and one output, the first input is the "main"
4277 video on which the second input is overlayed.
4279 This filter accepts the following parameters:
4281 A description of the accepted options follows.
4286 Set the expression for the x and y coordinates of the overlayed video
4287 on the main video. Default value is "0" for both expressions. In case
4288 the expression is invalid, it is set to a huge value (meaning that the
4289 overlay will not be displayed within the output visible area).
4292 Set the expression which enables the overlay. If the evaluation is
4293 different from 0, the overlay is displayed on top of the input
4294 frame. By default it is "1".
4297 Set when the expressions for @option{x}, @option{y}, and
4298 @option{enable} are evaluated.
4300 It accepts the following values:
4303 only evaluate expressions once during the filter initialization or
4304 when a command is processed
4307 evaluate expressions for each incoming frame
4310 Default value is @samp{frame}.
4313 If set to 1, force the output to terminate when the shortest input
4314 terminates. Default value is 0.
4317 Set the format for the output video.
4319 It accepts the following values:
4331 Default value is @samp{yuv420}.
4333 @item rgb @emph{(deprecated)}
4334 If set to 1, force the filter to accept inputs in the RGB
4335 color space. Default value is 0. This option is deprecated, use
4336 @option{format} instead.
4339 The @option{x}, @option{y}, and @option{enable} expressions can
4340 contain the following parameters.
4345 main input width and height
4349 overlay input width and height
4353 the computed values for @var{x} and @var{y}. They are evaluated for
4358 horizontal and vertical chroma subsample values of the output
4359 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4363 the number of input frame, starting from 0
4366 the position in the file of the input frame, NAN if unknown
4369 timestamp expressed in seconds, NAN if the input timestamp is unknown
4372 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4373 when evaluation is done @emph{per frame}, and will evaluate to NAN
4374 when @option{eval} is set to @samp{init}.
4376 Be aware that frames are taken from each input video in timestamp
4377 order, hence, if their initial timestamps differ, it is a a good idea
4378 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4379 have them begin in the same zero timestamp, as it does the example for
4380 the @var{movie} filter.
4382 You can chain together more overlays but you should test the
4383 efficiency of such approach.
4385 @subsection Commands
4387 This filter supports the following command:
4390 Set the @option{x} option expression.
4393 Set the @option{y} option expression.
4396 Set the @option{enable} option expression.
4399 @subsection Examples
4403 Draw the overlay at 10 pixels from the bottom right corner of the main
4406 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4409 Using named options the example above becomes:
4411 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4415 Insert a transparent PNG logo in the bottom left corner of the input,
4416 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4418 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4422 Insert 2 different transparent PNG logos (second logo on bottom
4423 right corner) using the @command{ffmpeg} tool:
4425 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
4429 Add a transparent color layer on top of the main video, @code{WxH}
4430 must specify the size of the main input to the overlay filter:
4432 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4436 Play an original video and a filtered version (here with the deshake
4437 filter) side by side using the @command{ffplay} tool:
4439 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4442 The above command is the same as:
4444 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4448 Make a sliding overlay appearing from the left to the right top part of the
4449 screen starting since time 2:
4451 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4455 Compose output by putting two input videos side to side:
4457 ffmpeg -i left.avi -i right.avi -filter_complex "
4458 nullsrc=size=200x100 [background];
4459 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4460 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4461 [background][left] overlay=shortest=1 [background+left];
4462 [background+left][right] overlay=shortest=1:x=100 [left+right]
4467 Chain several overlays in cascade:
4469 nullsrc=s=200x200 [bg];
4470 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4471 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4472 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4473 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4474 [in3] null, [mid2] overlay=100:100 [out0]
4481 Add paddings to the input image, and place the original input at the
4482 given coordinates @var{x}, @var{y}.
4484 This filter accepts the following parameters:
4489 Specify an expression for the size of the output image with the
4490 paddings added. If the value for @var{width} or @var{height} is 0, the
4491 corresponding input size is used for the output.
4493 The @var{width} expression can reference the value set by the
4494 @var{height} expression, and vice versa.
4496 The default value of @var{width} and @var{height} is 0.
4500 Specify an expression for the offsets where to place the input image
4501 in the padded area with respect to the top/left border of the output
4504 The @var{x} expression can reference the value set by the @var{y}
4505 expression, and vice versa.
4507 The default value of @var{x} and @var{y} is 0.
4510 Specify the color of the padded area, it can be the name of a color
4511 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4513 The default value of @var{color} is "black".
4516 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4517 options are expressions containing the following constants:
4521 the input video width and height
4524 same as @var{in_w} and @var{in_h}
4527 the output width and height, that is the size of the padded area as
4528 specified by the @var{width} and @var{height} expressions
4531 same as @var{out_w} and @var{out_h}
4534 x and y offsets as specified by the @var{x} and @var{y}
4535 expressions, or NAN if not yet specified
4538 same as @var{iw} / @var{ih}
4541 input sample aspect ratio
4544 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4547 horizontal and vertical chroma subsample values. For example for the
4548 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4551 @subsection Examples
4555 Add paddings with color "violet" to the input video. Output video
4556 size is 640x480, the top-left corner of the input video is placed at
4559 pad=640:480:0:40:violet
4562 The example above is equivalent to the following command:
4564 pad=width=640:height=480:x=0:y=40:color=violet
4568 Pad the input to get an output with dimensions increased by 3/2,
4569 and put the input video at the center of the padded area:
4571 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4575 Pad the input to get a squared output with size equal to the maximum
4576 value between the input width and height, and put the input video at
4577 the center of the padded area:
4579 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4583 Pad the input to get a final w/h ratio of 16:9:
4585 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4589 In case of anamorphic video, in order to set the output display aspect
4590 correctly, it is necessary to use @var{sar} in the expression,
4591 according to the relation:
4593 (ih * X / ih) * sar = output_dar
4594 X = output_dar / sar
4597 Thus the previous example needs to be modified to:
4599 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4603 Double output size and put the input video in the bottom-right
4604 corner of the output padded area:
4606 pad="2*iw:2*ih:ow-iw:oh-ih"
4610 @section pixdesctest
4612 Pixel format descriptor test filter, mainly useful for internal
4613 testing. The output video should be equal to the input video.
4617 format=monow, pixdesctest
4620 can be used to test the monowhite pixel format descriptor definition.
4624 Enable the specified chain of postprocessing subfilters using libpostproc. This
4625 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4626 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4627 Each subfilter and some options have a short and a long name that can be used
4628 interchangeably, i.e. dr/dering are the same.
4630 The filters accept the following options:
4634 Set postprocessing subfilters string.
4637 All subfilters share common options to determine their scope:
4641 Honor the quality commands for this subfilter.
4644 Do chrominance filtering, too (default).
4647 Do luminance filtering only (no chrominance).
4650 Do chrominance filtering only (no luminance).
4653 These options can be appended after the subfilter name, separated by a '|'.
4655 Available subfilters are:
4658 @item hb/hdeblock[|difference[|flatness]]
4659 Horizontal deblocking filter
4662 Difference factor where higher values mean more deblocking (default: @code{32}).
4664 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4667 @item vb/vdeblock[|difference[|flatness]]
4668 Vertical deblocking filter
4671 Difference factor where higher values mean more deblocking (default: @code{32}).
4673 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4676 @item ha/hadeblock[|difference[|flatness]]
4677 Accurate horizontal deblocking filter
4680 Difference factor where higher values mean more deblocking (default: @code{32}).
4682 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4685 @item va/vadeblock[|difference[|flatness]]
4686 Accurate vertical deblocking filter
4689 Difference factor where higher values mean more deblocking (default: @code{32}).
4691 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4695 The horizontal and vertical deblocking filters share the difference and
4696 flatness values so you cannot set different horizontal and vertical
4701 Experimental horizontal deblocking filter
4704 Experimental vertical deblocking filter
4709 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4712 larger -> stronger filtering
4714 larger -> stronger filtering
4716 larger -> stronger filtering
4719 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4722 Stretch luminance to @code{0-255}.
4725 @item lb/linblenddeint
4726 Linear blend deinterlacing filter that deinterlaces the given block by
4727 filtering all lines with a @code{(1 2 1)} filter.
4729 @item li/linipoldeint
4730 Linear interpolating deinterlacing filter that deinterlaces the given block by
4731 linearly interpolating every second line.
4733 @item ci/cubicipoldeint
4734 Cubic interpolating deinterlacing filter deinterlaces the given block by
4735 cubically interpolating every second line.
4737 @item md/mediandeint
4738 Median deinterlacing filter that deinterlaces the given block by applying a
4739 median filter to every second line.
4741 @item fd/ffmpegdeint
4742 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4743 second line with a @code{(-1 4 2 4 -1)} filter.
4746 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4747 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4749 @item fq/forceQuant[|quantizer]
4750 Overrides the quantizer table from the input with the constant quantizer you
4758 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4761 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4764 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4767 @subsection Examples
4771 Apply horizontal and vertical deblocking, deringing and automatic
4772 brightness/contrast:
4778 Apply default filters without brightness/contrast correction:
4784 Apply default filters and temporal denoiser:
4786 pp=default/tmpnoise|1|2|3
4790 Apply deblocking on luminance only, and switch vertical deblocking on or off
4791 automatically depending on available CPU time:
4799 Suppress a TV station logo, using an image file to determine which
4800 pixels comprise the logo. It works by filling in the pixels that
4801 comprise the logo with neighboring pixels.
4803 This filter requires one argument which specifies the filter bitmap
4804 file, which can be any image format supported by libavformat. The
4805 width and height of the image file must match those of the video
4806 stream being processed.
4808 Pixels in the provided bitmap image with a value of zero are not
4809 considered part of the logo, non-zero pixels are considered part of
4810 the logo. If you use white (255) for the logo and black (0) for the
4811 rest, you will be safe. For making the filter bitmap, it is
4812 recommended to take a screen capture of a black frame with the logo
4813 visible, and then using a threshold filter followed by the erode
4814 filter once or twice.
4816 If needed, little splotches can be fixed manually. Remember that if
4817 logo pixels are not covered, the filter quality will be much
4818 reduced. Marking too many pixels as part of the logo does not hurt as
4819 much, but it will increase the amount of blurring needed to cover over
4820 the image and will destroy more information than necessary, and extra
4821 pixels will slow things down on a large logo.
4825 Scale (resize) the input video, using the libswscale library.
4827 The scale filter forces the output display aspect ratio to be the same
4828 of the input, by changing the output sample aspect ratio.
4830 This filter accepts a list of named options in the form of
4831 @var{key}=@var{value} pairs separated by ":". If the key for the first
4832 two options is not specified, the assumed keys for the first two
4833 values are @code{w} and @code{h}. If the first option has no key and
4834 can be interpreted like a video size specification, it will be used
4835 to set the video size.
4837 A description of the accepted options follows.
4842 default value is @code{iw}. See below
4843 for the list of accepted constants.
4846 Output video height.
4847 default value is @code{ih}.
4848 See below for the list of accepted constants.
4851 Set the interlacing. It accepts the following values:
4855 force interlaced aware scaling
4858 do not apply interlaced scaling
4861 select interlaced aware scaling depending on whether the source frames
4862 are flagged as interlaced or not
4865 Default value is @code{0}.
4868 Set libswscale scaling flags. If not explictly specified the filter
4869 applies a bilinear scaling algorithm.
4872 Set the video size, the value must be a valid abbreviation or in the
4873 form @var{width}x@var{height}.
4876 The values of the @var{w} and @var{h} options are expressions
4877 containing the following constants:
4881 the input width and height
4884 same as @var{in_w} and @var{in_h}
4887 the output (cropped) width and height
4890 same as @var{out_w} and @var{out_h}
4893 same as @var{iw} / @var{ih}
4896 input sample aspect ratio
4899 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4902 horizontal and vertical chroma subsample values. For example for the
4903 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4906 If the input image format is different from the format requested by
4907 the next filter, the scale filter will convert the input to the
4910 If the value for @var{w} or @var{h} is 0, the respective input
4911 size is used for the output.
4913 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4914 respective output size, a value that maintains the aspect ratio of the input
4917 @subsection Examples
4921 Scale the input video to a size of 200x100:
4926 This is equivalent to:
4937 Specify a size abbreviation for the output size:
4942 which can also be written as:
4948 Scale the input to 2x:
4954 The above is the same as:
4960 Scale the input to 2x with forced interlaced scaling:
4962 scale=2*iw:2*ih:interl=1
4966 Scale the input to half size:
4972 Increase the width, and set the height to the same size:
4978 Seek for Greek harmony:
4985 Increase the height, and set the width to 3/2 of the height:
4987 scale=w=3/2*oh:h=3/5*ih
4991 Increase the size, but make the size a multiple of the chroma
4994 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4998 Increase the width to a maximum of 500 pixels, keep the same input
5001 scale=w='min(500\, iw*3/2):h=-1'
5005 @section separatefields
5007 The @code{separatefields} takes a frame-based video input and splits
5008 each frame into its components fields, producing a new half height clip
5009 with twice the frame rate and twice the frame count.
5011 This filter use field-dominance information in frame to decide which
5012 of each pair of fields to place first in the output.
5013 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
5015 @section setdar, setsar
5017 The @code{setdar} filter sets the Display Aspect Ratio for the filter
5020 This is done by changing the specified Sample (aka Pixel) Aspect
5021 Ratio, according to the following equation:
5023 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
5026 Keep in mind that the @code{setdar} filter does not modify the pixel
5027 dimensions of the video frame. Also the display aspect ratio set by
5028 this filter may be changed by later filters in the filterchain,
5029 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5032 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5033 the filter output video.
5035 Note that as a consequence of the application of this filter, the
5036 output display aspect ratio will change according to the equation
5039 Keep in mind that the sample aspect ratio set by the @code{setsar}
5040 filter may be changed by later filters in the filterchain, e.g. if
5041 another "setsar" or a "setdar" filter is applied.
5043 The @code{setdar} and @code{setsar} filters accept a string in the
5044 form @var{num}:@var{den} expressing an aspect ratio, or the following
5045 named options, expressed as a sequence of @var{key}=@var{value} pairs,
5050 Set the maximum integer value to use for expressing numerator and
5051 denominator when reducing the expressed aspect ratio to a rational.
5052 Default value is @code{100}.
5054 @item r, ratio, dar, sar:
5055 Set the aspect ratio used by the filter.
5057 The parameter can be a floating point number string, an expression, or
5058 a string of the form @var{num}:@var{den}, where @var{num} and
5059 @var{den} are the numerator and denominator of the aspect ratio. If
5060 the parameter is not specified, it is assumed the value "0".
5061 In case the form "@var{num}:@var{den}" the @code{:} character should
5065 If the keys are omitted in the named options list, the specifed values
5066 are assumed to be @var{ratio} and @var{max} in that order.
5068 For example to change the display aspect ratio to 16:9, specify:
5071 # the above is equivalent to
5077 To change the sample aspect ratio to 10:11, specify:
5080 # the above is equivalent to
5084 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5085 1000 in the aspect ratio reduction, use the command:
5087 setdar=ratio='16:9':max=1000
5093 Force field for the output video frame.
5095 The @code{setfield} filter marks the interlace type field for the
5096 output frames. It does not change the input frame, but only sets the
5097 corresponding property, which affects how the frame is treated by
5098 following filters (e.g. @code{fieldorder} or @code{yadif}).
5100 The filter accepts the following options:
5105 Available values are:
5109 Keep the same field property.
5112 Mark the frame as bottom-field-first.
5115 Mark the frame as top-field-first.
5118 Mark the frame as progressive.
5124 Show a line containing various information for each input video frame.
5125 The input video is not modified.
5127 The shown line contains a sequence of key/value pairs of the form
5128 @var{key}:@var{value}.
5130 A description of each shown parameter follows:
5134 sequential number of the input frame, starting from 0
5137 Presentation TimeStamp of the input frame, expressed as a number of
5138 time base units. The time base unit depends on the filter input pad.
5141 Presentation TimeStamp of the input frame, expressed as a number of
5145 position of the frame in the input stream, -1 if this information in
5146 unavailable and/or meaningless (for example in case of synthetic video)
5152 sample aspect ratio of the input frame, expressed in the form
5156 size of the input frame, expressed in the form
5157 @var{width}x@var{height}
5160 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5161 for bottom field first)
5164 1 if the frame is a key frame, 0 otherwise
5167 picture type of the input frame ("I" for an I-frame, "P" for a
5168 P-frame, "B" for a B-frame, "?" for unknown type).
5169 Check also the documentation of the @code{AVPictureType} enum and of
5170 the @code{av_get_picture_type_char} function defined in
5171 @file{libavutil/avutil.h}.
5174 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5176 @item plane_checksum
5177 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5178 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5183 Blur the input video without impacting the outlines.
5185 The filter accepts the following options:
5188 @item luma_radius, lr
5189 Set the luma radius. The option value must be a float number in
5190 the range [0.1,5.0] that specifies the variance of the gaussian filter
5191 used to blur the image (slower if larger). Default value is 1.0.
5193 @item luma_strength, ls
5194 Set the luma strength. The option value must be a float number
5195 in the range [-1.0,1.0] that configures the blurring. A value included
5196 in [0.0,1.0] will blur the image whereas a value included in
5197 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5199 @item luma_threshold, lt
5200 Set the luma threshold used as a coefficient to determine
5201 whether a pixel should be blurred or not. The option value must be an
5202 integer in the range [-30,30]. A value of 0 will filter all the image,
5203 a value included in [0,30] will filter flat areas and a value included
5204 in [-30,0] will filter edges. Default value is 0.
5206 @item chroma_radius, cr
5207 Set the chroma radius. The option value must be a float number in
5208 the range [0.1,5.0] that specifies the variance of the gaussian filter
5209 used to blur the image (slower if larger). Default value is 1.0.
5211 @item chroma_strength, cs
5212 Set the chroma strength. The option value must be a float number
5213 in the range [-1.0,1.0] that configures the blurring. A value included
5214 in [0.0,1.0] will blur the image whereas a value included in
5215 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5217 @item chroma_threshold, ct
5218 Set the chroma threshold used as a coefficient to determine
5219 whether a pixel should be blurred or not. The option value must be an
5220 integer in the range [-30,30]. A value of 0 will filter all the image,
5221 a value included in [0,30] will filter flat areas and a value included
5222 in [-30,0] will filter edges. Default value is 0.
5225 If a chroma option is not explicitly set, the corresponding luma value
5230 Convert between different stereoscopic image formats.
5232 The filters accept the following options:
5236 Set stereoscopic image format of input.
5238 Available values for input image formats are:
5241 side by side parallel (left eye left, right eye right)
5244 side by side crosseye (right eye left, left eye right)
5247 side by side parallel with half width resolution
5248 (left eye left, right eye right)
5251 side by side crosseye with half width resolution
5252 (right eye left, left eye right)
5255 above-below (left eye above, right eye below)
5258 above-below (right eye above, left eye below)
5261 above-below with half height resolution
5262 (left eye above, right eye below)
5265 above-below with half height resolution
5266 (right eye above, left eye below)
5268 Default value is @samp{sbsl}.
5272 Set stereoscopic image format of output.
5274 Available values for output image formats are all the input formats as well as:
5277 anaglyph red/blue gray
5278 (red filter on left eye, blue filter on right eye)
5281 anaglyph red/green gray
5282 (red filter on left eye, green filter on right eye)
5285 anaglyph red/cyan gray
5286 (red filter on left eye, cyan filter on right eye)
5289 anaglyph red/cyan half colored
5290 (red filter on left eye, cyan filter on right eye)
5293 anaglyph red/cyan color
5294 (red filter on left eye, cyan filter on right eye)
5297 anaglyph red/cyan color optimized with the least squares projection of dubois
5298 (red filter on left eye, cyan filter on right eye)
5301 anaglyph green/magenta gray
5302 (green filter on left eye, magenta filter on right eye)
5305 anaglyph green/magenta half colored
5306 (green filter on left eye, magenta filter on right eye)
5309 anaglyph green/magenta colored
5310 (green filter on left eye, magenta filter on right eye)
5313 anaglyph green/magenta color optimized with the least squares projection of dubois
5314 (green filter on left eye, magenta filter on right eye)
5317 anaglyph yellow/blue gray
5318 (yellow filter on left eye, blue filter on right eye)
5321 anaglyph yellow/blue half colored
5322 (yellow filter on left eye, blue filter on right eye)
5325 anaglyph yellow/blue colored
5326 (yellow filter on left eye, blue filter on right eye)
5329 anaglyph yellow/blue color optimized with the least squares projection of dubois
5330 (yellow filter on left eye, blue filter on right eye)
5333 interleaved rows (left eye has top row, right eye starts on next row)
5336 interleaved rows (right eye has top row, left eye starts on next row)
5339 mono output (left eye only)
5342 mono output (right eye only)
5345 Default value is @samp{arcd}.
5351 Draw subtitles on top of input video using the libass library.
5353 To enable compilation of this filter you need to configure FFmpeg with
5354 @code{--enable-libass}. This filter also requires a build with libavcodec and
5355 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5356 Alpha) subtitles format.
5358 The filter accepts the following options:
5362 Set the filename of the subtitle file to read. It must be specified.
5365 Specify the size of the original video, the video for which the ASS file
5366 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5367 necessary to correctly scale the fonts if the aspect ratio has been changed.
5370 Set subtitles input character encoding. @code{subtitles} filter only. Only
5371 useful if not UTF-8.
5374 If the first key is not specified, it is assumed that the first value
5375 specifies the @option{filename}.
5377 For example, to render the file @file{sub.srt} on top of the input
5378 video, use the command:
5383 which is equivalent to:
5385 subtitles=filename=sub.srt
5390 Split input video into several identical outputs.
5392 The filter accepts a single parameter which specifies the number of outputs. If
5393 unspecified, it defaults to 2.
5397 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5399 will create 5 copies of the input video.
5403 [in] split [splitout1][splitout2];
5404 [splitout1] crop=100:100:0:0 [cropout];
5405 [splitout2] pad=200:200:100:100 [padout];
5408 will create two separate outputs from the same input, one cropped and
5413 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5414 Interpolate) pixel art scaling algorithm.
5416 Useful for enlarging pixel art images without reducing sharpness.
5422 Select the most representative frame in a given sequence of consecutive frames.
5424 The filter accepts the following options:
5428 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5429 will pick one of them, and then handle the next batch of @var{n} frames until
5430 the end. Default is @code{100}.
5433 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5434 value will result in a higher memory usage, so a high value is not recommended.
5436 @subsection Examples
5440 Extract one picture each 50 frames:
5446 Complete example of a thumbnail creation with @command{ffmpeg}:
5448 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5454 Tile several successive frames together.
5456 The filter accepts the following options:
5461 Set the grid size (i.e. the number of lines and columns) in the form
5465 Set the maximum number of frames to render in the given area. It must be less
5466 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5467 the area will be used.
5470 Set the outer border margin in pixels.
5473 Set the inner border thickness (i.e. the number of pixels between frames). For
5474 more advanced padding options (such as having different values for the edges),
5475 refer to the pad video filter.
5479 @subsection Examples
5483 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5485 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5487 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5488 duplicating each output frame to accomodate the originally detected frame
5492 Display @code{5} pictures in an area of @code{3x2} frames,
5493 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5494 mixed flat and named options:
5496 tile=3x2:nb_frames=5:padding=7:margin=2
5502 Perform various types of temporal field interlacing.
5504 Frames are counted starting from 1, so the first input frame is
5507 The filter accepts the following options:
5512 Specify the mode of the interlacing. This option can also be specified
5513 as a value alone. See below for a list of values for this option.
5515 Available values are:
5519 Move odd frames into the upper field, even into the lower field,
5520 generating a double height frame at half frame rate.
5523 Only output even frames, odd frames are dropped, generating a frame with
5524 unchanged height at half frame rate.
5527 Only output odd frames, even frames are dropped, generating a frame with
5528 unchanged height at half frame rate.
5531 Expand each frame to full height, but pad alternate lines with black,
5532 generating a frame with double height at the same input frame rate.
5534 @item interleave_top, 4
5535 Interleave the upper field from odd frames with the lower field from
5536 even frames, generating a frame with unchanged height at half frame rate.
5538 @item interleave_bottom, 5
5539 Interleave the lower field from odd frames with the upper field from
5540 even frames, generating a frame with unchanged height at half frame rate.
5542 @item interlacex2, 6
5543 Double frame rate with unchanged height. Frames are inserted each
5544 containing the second temporal field from the previous input frame and
5545 the first temporal field from the next input frame. This mode relies on
5546 the top_field_first flag. Useful for interlaced video displays with no
5547 field synchronisation.
5550 Numeric values are deprecated but are accepted for backward
5551 compatibility reasons.
5553 Default mode is @code{merge}.
5556 Specify flags influencing the filter process.
5558 Available value for @var{flags} is:
5561 @item low_pass_filter, vlfp
5562 Enable vertical low-pass filtering in the filter.
5563 Vertical low-pass filtering is required when creating an interlaced
5564 destination from a progressive source which contains high-frequency
5565 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5568 Vertical low-pass filtering can only be enabled for @option{mode}
5569 @var{interleave_top} and @var{interleave_bottom}.
5576 Transpose rows with columns in the input video and optionally flip it.
5578 This filter accepts the following options:
5583 The direction of the transpose.
5586 @item 0, 4, cclock_flip
5587 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5595 Rotate by 90 degrees clockwise, that is:
5603 Rotate by 90 degrees counterclockwise, that is:
5610 @item 3, 7, clock_flip
5611 Rotate by 90 degrees clockwise and vertically flip, that is:
5619 For values between 4-7, the transposition is only done if the input
5620 video geometry is portrait and not landscape. These values are
5621 deprecated, the @code{passthrough} option should be used instead.
5624 Do not apply the transposition if the input geometry matches the one
5625 specified by the specified value. It accepts the following values:
5628 Always apply transposition.
5630 Preserve portrait geometry (when @var{height} >= @var{width}).
5632 Preserve landscape geometry (when @var{width} >= @var{height}).
5635 Default value is @code{none}.
5638 For example to rotate by 90 degrees clockwise and preserve portrait
5641 transpose=dir=1:passthrough=portrait
5644 The command above can also be specified as:
5646 transpose=1:portrait
5651 Sharpen or blur the input video.
5653 It accepts the following parameters:
5656 @item luma_msize_x, lx
5657 @item chroma_msize_x, cx
5658 Set the luma/chroma matrix horizontal size. It must be an odd integer
5659 between 3 and 63, default value is 5.
5661 @item luma_msize_y, ly
5662 @item chroma_msize_y, cy
5663 Set the luma/chroma matrix vertical size. It must be an odd integer
5664 between 3 and 63, default value is 5.
5666 @item luma_amount, la
5667 @item chroma_amount, ca
5668 Set the luma/chroma effect strength. It can be a float number,
5669 reasonable values lay between -1.5 and 1.5.
5671 Negative values will blur the input video, while positive values will
5672 sharpen it, a value of zero will disable the effect.
5674 Default value is 1.0 for @option{luma_amount}, 0.0 for
5675 @option{chroma_amount}.
5678 All parameters are optional and default to the
5679 equivalent of the string '5:5:1.0:5:5:0.0'.
5681 @subsection Examples
5685 Apply strong luma sharpen effect:
5687 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5691 Apply strong blur of both luma and chroma parameters:
5693 unsharp=7:7:-2:7:7:-2
5699 Flip the input video vertically.
5702 ffmpeg -i in.avi -vf "vflip" out.avi
5707 Deinterlace the input video ("yadif" means "yet another deinterlacing
5710 This filter accepts the following options:
5716 The interlacing mode to adopt, accepts one of the following values:
5720 output 1 frame for each frame
5722 output 1 frame for each field
5723 @item 2, send_frame_nospatial
5724 like @code{send_frame} but skip spatial interlacing check
5725 @item 3, send_field_nospatial
5726 like @code{send_field} but skip spatial interlacing check
5729 Default value is @code{send_frame}.
5732 The picture field parity assumed for the input interlaced video, accepts one of
5733 the following values:
5737 assume top field first
5739 assume bottom field first
5741 enable automatic detection
5744 Default value is @code{auto}.
5745 If interlacing is unknown or decoder does not export this information,
5746 top field first will be assumed.
5749 Specify which frames to deinterlace. Accept one of the following
5754 deinterlace all frames
5756 only deinterlace frames marked as interlaced
5759 Default value is @code{all}.
5762 @c man end VIDEO FILTERS
5764 @chapter Video Sources
5765 @c man begin VIDEO SOURCES
5767 Below is a description of the currently available video sources.
5771 Buffer video frames, and make them available to the filter chain.
5773 This source is mainly intended for a programmatic use, in particular
5774 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5776 It accepts a list of options in the form of @var{key}=@var{value} pairs
5777 separated by ":". A description of the accepted options follows.
5782 Specify the size (width and height) of the buffered video frames.
5791 A string representing the pixel format of the buffered video frames.
5792 It may be a number corresponding to a pixel format, or a pixel format
5796 Specify the timebase assumed by the timestamps of the buffered frames.
5799 Specify the frame rate expected for the video stream.
5801 @item pixel_aspect, sar
5802 Specify the sample aspect ratio assumed by the video frames.
5805 Specify the optional parameters to be used for the scale filter which
5806 is automatically inserted when an input change is detected in the
5807 input size or format.
5812 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
5815 will instruct the source to accept video frames with size 320x240 and
5816 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5817 square pixels (1:1 sample aspect ratio).
5818 Since the pixel format with name "yuv410p" corresponds to the number 6
5819 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5820 this example corresponds to:
5822 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5825 Alternatively, the options can be specified as a flat string, but this
5826 syntax is deprecated:
5828 @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}]
5832 Create a pattern generated by an elementary cellular automaton.
5834 The initial state of the cellular automaton can be defined through the
5835 @option{filename}, and @option{pattern} options. If such options are
5836 not specified an initial state is created randomly.
5838 At each new frame a new row in the video is filled with the result of
5839 the cellular automaton next generation. The behavior when the whole
5840 frame is filled is defined by the @option{scroll} option.
5842 This source accepts the following options:
5846 Read the initial cellular automaton state, i.e. the starting row, from
5848 In the file, each non-whitespace character is considered an alive
5849 cell, a newline will terminate the row, and further characters in the
5850 file will be ignored.
5853 Read the initial cellular automaton state, i.e. the starting row, from
5854 the specified string.
5856 Each non-whitespace character in the string is considered an alive
5857 cell, a newline will terminate the row, and further characters in the
5858 string will be ignored.
5861 Set the video rate, that is the number of frames generated per second.
5864 @item random_fill_ratio, ratio
5865 Set the random fill ratio for the initial cellular automaton row. It
5866 is a floating point number value ranging from 0 to 1, defaults to
5869 This option is ignored when a file or a pattern is specified.
5871 @item random_seed, seed
5872 Set the seed for filling randomly the initial row, must be an integer
5873 included between 0 and UINT32_MAX. If not specified, or if explicitly
5874 set to -1, the filter will try to use a good random seed on a best
5878 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5879 Default value is 110.
5882 Set the size of the output video.
5884 If @option{filename} or @option{pattern} is specified, the size is set
5885 by default to the width of the specified initial state row, and the
5886 height is set to @var{width} * PHI.
5888 If @option{size} is set, it must contain the width of the specified
5889 pattern string, and the specified pattern will be centered in the
5892 If a filename or a pattern string is not specified, the size value
5893 defaults to "320x518" (used for a randomly generated initial state).
5896 If set to 1, scroll the output upward when all the rows in the output
5897 have been already filled. If set to 0, the new generated row will be
5898 written over the top row just after the bottom row is filled.
5901 @item start_full, full
5902 If set to 1, completely fill the output with generated rows before
5903 outputting the first frame.
5904 This is the default behavior, for disabling set the value to 0.
5907 If set to 1, stitch the left and right row edges together.
5908 This is the default behavior, for disabling set the value to 0.
5911 @subsection Examples
5915 Read the initial state from @file{pattern}, and specify an output of
5918 cellauto=f=pattern:s=200x400
5922 Generate a random initial row with a width of 200 cells, with a fill
5925 cellauto=ratio=2/3:s=200x200
5929 Create a pattern generated by rule 18 starting by a single alive cell
5930 centered on an initial row with width 100:
5932 cellauto=p=@@:s=100x400:full=0:rule=18
5936 Specify a more elaborated initial pattern:
5938 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5945 Generate a Mandelbrot set fractal, and progressively zoom towards the
5946 point specified with @var{start_x} and @var{start_y}.
5948 This source accepts the following options:
5953 Set the terminal pts value. Default value is 400.
5956 Set the terminal scale value.
5957 Must be a floating point value. Default value is 0.3.
5960 Set the inner coloring mode, that is the algorithm used to draw the
5961 Mandelbrot fractal internal region.
5963 It shall assume one of the following values:
5968 Show time until convergence.
5970 Set color based on point closest to the origin of the iterations.
5975 Default value is @var{mincol}.
5978 Set the bailout value. Default value is 10.0.
5981 Set the maximum of iterations performed by the rendering
5982 algorithm. Default value is 7189.
5985 Set outer coloring mode.
5986 It shall assume one of following values:
5988 @item iteration_count
5989 Set iteration cound mode.
5990 @item normalized_iteration_count
5991 set normalized iteration count mode.
5993 Default value is @var{normalized_iteration_count}.
5996 Set frame rate, expressed as number of frames per second. Default
6000 Set frame size. Default value is "640x480".
6003 Set the initial scale value. Default value is 3.0.
6006 Set the initial x position. Must be a floating point value between
6007 -100 and 100. Default value is -0.743643887037158704752191506114774.
6010 Set the initial y position. Must be a floating point value between
6011 -100 and 100. Default value is -0.131825904205311970493132056385139.
6016 Generate various test patterns, as generated by the MPlayer test filter.
6018 The size of the generated video is fixed, and is 256x256.
6019 This source is useful in particular for testing encoding features.
6021 This source accepts the following options:
6026 Specify the frame rate of the sourced video, as the number of frames
6027 generated per second. It has to be a string in the format
6028 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6029 number or a valid video frame rate abbreviation. The default value is
6033 Set the video duration of the sourced video. The accepted syntax is:
6038 See also the function @code{av_parse_time()}.
6040 If not specified, or the expressed duration is negative, the video is
6041 supposed to be generated forever.
6045 Set the number or the name of the test to perform. Supported tests are:
6060 Default value is "all", which will cycle through the list of all tests.
6063 For example the following:
6068 will generate a "dc_luma" test pattern.
6072 Provide a frei0r source.
6074 To enable compilation of this filter you need to install the frei0r
6075 header and configure FFmpeg with @code{--enable-frei0r}.
6077 This source accepts the following options:
6082 The size of the video to generate, may be a string of the form
6083 @var{width}x@var{height} or a frame size abbreviation.
6086 Framerate of the generated video, may be a string of the form
6087 @var{num}/@var{den} or a frame rate abbreviation.
6090 The name to the frei0r source to load. For more information regarding frei0r and
6091 how to set the parameters read the section @ref{frei0r} in the description of
6095 A '|'-separated list of parameters to pass to the frei0r source.
6099 For example, to generate a frei0r partik0l source with size 200x200
6100 and frame rate 10 which is overlayed on the overlay filter main input:
6102 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6107 Generate a life pattern.
6109 This source is based on a generalization of John Conway's life game.
6111 The sourced input represents a life grid, each pixel represents a cell
6112 which can be in one of two possible states, alive or dead. Every cell
6113 interacts with its eight neighbours, which are the cells that are
6114 horizontally, vertically, or diagonally adjacent.
6116 At each interaction the grid evolves according to the adopted rule,
6117 which specifies the number of neighbor alive cells which will make a
6118 cell stay alive or born. The @option{rule} option allows to specify
6121 This source accepts the following options:
6125 Set the file from which to read the initial grid state. In the file,
6126 each non-whitespace character is considered an alive cell, and newline
6127 is used to delimit the end of each row.
6129 If this option is not specified, the initial grid is generated
6133 Set the video rate, that is the number of frames generated per second.
6136 @item random_fill_ratio, ratio
6137 Set the random fill ratio for the initial random grid. It is a
6138 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6139 It is ignored when a file is specified.
6141 @item random_seed, seed
6142 Set the seed for filling the initial random grid, must be an integer
6143 included between 0 and UINT32_MAX. If not specified, or if explicitly
6144 set to -1, the filter will try to use a good random seed on a best
6150 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6151 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6152 @var{NS} specifies the number of alive neighbor cells which make a
6153 live cell stay alive, and @var{NB} the number of alive neighbor cells
6154 which make a dead cell to become alive (i.e. to "born").
6155 "s" and "b" can be used in place of "S" and "B", respectively.
6157 Alternatively a rule can be specified by an 18-bits integer. The 9
6158 high order bits are used to encode the next cell state if it is alive
6159 for each number of neighbor alive cells, the low order bits specify
6160 the rule for "borning" new cells. Higher order bits encode for an
6161 higher number of neighbor cells.
6162 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6163 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6165 Default value is "S23/B3", which is the original Conway's game of life
6166 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6167 cells, and will born a new cell if there are three alive cells around
6171 Set the size of the output video.
6173 If @option{filename} is specified, the size is set by default to the
6174 same size of the input file. If @option{size} is set, it must contain
6175 the size specified in the input file, and the initial grid defined in
6176 that file is centered in the larger resulting area.
6178 If a filename is not specified, the size value defaults to "320x240"
6179 (used for a randomly generated initial grid).
6182 If set to 1, stitch the left and right grid edges together, and the
6183 top and bottom edges also. Defaults to 1.
6186 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6187 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6188 value from 0 to 255.
6191 Set the color of living (or new born) cells.
6194 Set the color of dead cells. If @option{mold} is set, this is the first color
6195 used to represent a dead cell.
6198 Set mold color, for definitely dead and moldy cells.
6201 @subsection Examples
6205 Read a grid from @file{pattern}, and center it on a grid of size
6208 life=f=pattern:s=300x300
6212 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6214 life=ratio=2/3:s=200x200
6218 Specify a custom rule for evolving a randomly generated grid:
6224 Full example with slow death effect (mold) using @command{ffplay}:
6226 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6230 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6232 The @code{color} source provides an uniformly colored input.
6234 The @code{nullsrc} source returns unprocessed video frames. It is
6235 mainly useful to be employed in analysis / debugging tools, or as the
6236 source for filters which ignore the input data.
6238 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6239 detecting RGB vs BGR issues. You should see a red, green and blue
6240 stripe from top to bottom.
6242 The @code{smptebars} source generates a color bars pattern, based on
6243 the SMPTE Engineering Guideline EG 1-1990.
6245 The @code{testsrc} source generates a test video pattern, showing a
6246 color pattern, a scrolling gradient and a timestamp. This is mainly
6247 intended for testing purposes.
6249 The sources accept the following options:
6254 Specify the color of the source, only used in the @code{color}
6255 source. It can be the name of a color (case insensitive match) or a
6256 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6257 default value is "black".
6260 Specify the size of the sourced video, it may be a string of the form
6261 @var{width}x@var{height}, or the name of a size abbreviation. The
6262 default value is "320x240".
6265 Specify the frame rate of the sourced video, as the number of frames
6266 generated per second. It has to be a string in the format
6267 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6268 number or a valid video frame rate abbreviation. The default value is
6272 Set the sample aspect ratio of the sourced video.
6275 Set the video duration of the sourced video. The accepted syntax is:
6277 [-]HH[:MM[:SS[.m...]]]
6280 See also the function @code{av_parse_time()}.
6282 If not specified, or the expressed duration is negative, the video is
6283 supposed to be generated forever.
6286 Set the number of decimals to show in the timestamp, only used in the
6287 @code{testsrc} source.
6289 The displayed timestamp value will correspond to the original
6290 timestamp value multiplied by the power of 10 of the specified
6291 value. Default value is 0.
6294 For example the following:
6296 testsrc=duration=5.3:size=qcif:rate=10
6299 will generate a video with a duration of 5.3 seconds, with size
6300 176x144 and a frame rate of 10 frames per second.
6302 The following graph description will generate a red source
6303 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6306 color=c=red@@0.2:s=qcif:r=10
6309 If the input content is to be ignored, @code{nullsrc} can be used. The
6310 following command generates noise in the luminance plane by employing
6311 the @code{geq} filter:
6313 nullsrc=s=256x256, geq=random(1)*255:128:128
6316 @c man end VIDEO SOURCES
6318 @chapter Video Sinks
6319 @c man begin VIDEO SINKS
6321 Below is a description of the currently available video sinks.
6325 Buffer video frames, and make them available to the end of the filter
6328 This sink is mainly intended for a programmatic use, in particular
6329 through the interface defined in @file{libavfilter/buffersink.h}.
6331 It does not require a string parameter in input, but you need to
6332 specify a pointer to a list of supported pixel formats terminated by
6333 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6334 when initializing this sink.
6338 Null video sink, do absolutely nothing with the input video. It is
6339 mainly useful as a template and to be employed in analysis / debugging
6342 @c man end VIDEO SINKS
6344 @chapter Multimedia Filters
6345 @c man begin MULTIMEDIA FILTERS
6347 Below is a description of the currently available multimedia filters.
6349 @section aperms, perms
6351 Set read/write permissions for the output frames.
6353 These filters are mainly aimed at developers to test direct path in the
6354 following filter in the filtergraph.
6356 The filters accept the following options:
6360 Select the permissions mode.
6362 It accepts the following values:
6365 Do nothing. This is the default.
6367 Set all the output frames read-only.
6369 Set all the output frames directly writable.
6371 Make the frame read-only if writable, and writable if read-only.
6373 Set each output frame read-only or writable randomly.
6377 Set the seed for the @var{random} mode, must be an integer included between
6378 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6379 @code{-1}, the filter will try to use a good random seed on a best effort
6383 Note: in case of auto-inserted filter between the permission filter and the
6384 following one, the permission might not be received as expected in that
6385 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6386 perms/aperms filter can avoid this problem.
6389 Add a phasing effect to the input audio.
6391 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6392 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6394 A description of the accepted parameters follows.
6398 Set input gain. Default is 0.4.
6401 Set output gain. Default is 0.74
6404 Set delay in milliseconds. Default is 3.0.
6407 Set decay. Default is 0.4.
6410 Set modulation speed in Hz. Default is 0.5.
6413 Set modulation type. Default is triangular.
6415 It accepts the following values:
6422 @section aselect, select
6423 Select frames to pass in output.
6425 This filter accepts the following options:
6430 An expression, which is evaluated for each input frame. If the expression is
6431 evaluated to a non-zero value, the frame is selected and passed to the output,
6432 otherwise it is discarded.
6436 The expression can contain the following constants:
6440 the sequential number of the filtered frame, starting from 0
6443 the sequential number of the selected frame, starting from 0
6445 @item prev_selected_n
6446 the sequential number of the last selected frame, NAN if undefined
6449 timebase of the input timestamps
6452 the PTS (Presentation TimeStamp) of the filtered video frame,
6453 expressed in @var{TB} units, NAN if undefined
6456 the PTS (Presentation TimeStamp) of the filtered video frame,
6457 expressed in seconds, NAN if undefined
6460 the PTS of the previously filtered video frame, NAN if undefined
6462 @item prev_selected_pts
6463 the PTS of the last previously filtered video frame, NAN if undefined
6465 @item prev_selected_t
6466 the PTS of the last previously selected video frame, NAN if undefined
6469 the PTS of the first video frame in the video, NAN if undefined
6472 the time of the first video frame in the video, NAN if undefined
6474 @item pict_type @emph{(video only)}
6475 the type of the filtered frame, can assume one of the following
6487 @item interlace_type @emph{(video only)}
6488 the frame interlace type, can assume one of the following values:
6491 the frame is progressive (not interlaced)
6493 the frame is top-field-first
6495 the frame is bottom-field-first
6498 @item consumed_sample_n @emph{(audio only)}
6499 the number of selected samples before the current frame
6501 @item samples_n @emph{(audio only)}
6502 the number of samples in the current frame
6504 @item sample_rate @emph{(audio only)}
6505 the input sample rate
6508 1 if the filtered frame is a key-frame, 0 otherwise
6511 the position in the file of the filtered frame, -1 if the information
6512 is not available (e.g. for synthetic video)
6514 @item scene @emph{(video only)}
6515 value between 0 and 1 to indicate a new scene; a low value reflects a low
6516 probability for the current frame to introduce a new scene, while a higher
6517 value means the current frame is more likely to be one (see the example below)
6521 The default value of the select expression is "1".
6523 @subsection Examples
6527 Select all frames in input:
6532 The example above is the same as:
6544 Select only I-frames:
6546 select='eq(pict_type\,I)'
6550 Select one frame every 100:
6552 select='not(mod(n\,100))'
6556 Select only frames contained in the 10-20 time interval:
6558 select='gte(t\,10)*lte(t\,20)'
6562 Select only I frames contained in the 10-20 time interval:
6564 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6568 Select frames with a minimum distance of 10 seconds:
6570 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6574 Use aselect to select only audio frames with samples number > 100:
6576 aselect='gt(samples_n\,100)'
6580 Create a mosaic of the first scenes:
6582 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6585 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6589 @section asendcmd, sendcmd
6591 Send commands to filters in the filtergraph.
6593 These filters read commands to be sent to other filters in the
6596 @code{asendcmd} must be inserted between two audio filters,
6597 @code{sendcmd} must be inserted between two video filters, but apart
6598 from that they act the same way.
6600 The specification of commands can be provided in the filter arguments
6601 with the @var{commands} option, or in a file specified by the
6602 @var{filename} option.
6604 These filters accept the following options:
6607 Set the commands to be read and sent to the other filters.
6609 Set the filename of the commands to be read and sent to the other
6613 @subsection Commands syntax
6615 A commands description consists of a sequence of interval
6616 specifications, comprising a list of commands to be executed when a
6617 particular event related to that interval occurs. The occurring event
6618 is typically the current frame time entering or leaving a given time
6621 An interval is specified by the following syntax:
6623 @var{START}[-@var{END}] @var{COMMANDS};
6626 The time interval is specified by the @var{START} and @var{END} times.
6627 @var{END} is optional and defaults to the maximum time.
6629 The current frame time is considered within the specified interval if
6630 it is included in the interval [@var{START}, @var{END}), that is when
6631 the time is greater or equal to @var{START} and is lesser than
6634 @var{COMMANDS} consists of a sequence of one or more command
6635 specifications, separated by ",", relating to that interval. The
6636 syntax of a command specification is given by:
6638 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6641 @var{FLAGS} is optional and specifies the type of events relating to
6642 the time interval which enable sending the specified command, and must
6643 be a non-null sequence of identifier flags separated by "+" or "|" and
6644 enclosed between "[" and "]".
6646 The following flags are recognized:
6649 The command is sent when the current frame timestamp enters the
6650 specified interval. In other words, the command is sent when the
6651 previous frame timestamp was not in the given interval, and the
6655 The command is sent when the current frame timestamp leaves the
6656 specified interval. In other words, the command is sent when the
6657 previous frame timestamp was in the given interval, and the
6661 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6664 @var{TARGET} specifies the target of the command, usually the name of
6665 the filter class or a specific filter instance name.
6667 @var{COMMAND} specifies the name of the command for the target filter.
6669 @var{ARG} is optional and specifies the optional list of argument for
6670 the given @var{COMMAND}.
6672 Between one interval specification and another, whitespaces, or
6673 sequences of characters starting with @code{#} until the end of line,
6674 are ignored and can be used to annotate comments.
6676 A simplified BNF description of the commands specification syntax
6679 @var{COMMAND_FLAG} ::= "enter" | "leave"
6680 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6681 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6682 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6683 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6684 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6687 @subsection Examples
6691 Specify audio tempo change at second 4:
6693 asendcmd=c='4.0 atempo tempo 1.5',atempo
6697 Specify a list of drawtext and hue commands in a file.
6699 # show text in the interval 5-10
6700 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6701 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6703 # desaturate the image in the interval 15-20
6704 15.0-20.0 [enter] hue reinit s=0,
6705 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6706 [leave] hue reinit s=1,
6707 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6709 # apply an exponential saturation fade-out effect, starting from time 25
6710 25 [enter] hue s=exp(t-25)
6713 A filtergraph allowing to read and process the above command list
6714 stored in a file @file{test.cmd}, can be specified with:
6716 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6721 @section asetpts, setpts
6723 Change the PTS (presentation timestamp) of the input frames.
6725 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6727 This filter accepts the following options:
6732 The expression which is evaluated for each frame to construct its timestamp.
6736 The expression is evaluated through the eval API and can contain the following
6741 frame rate, only defined for constant frame-rate video
6744 the presentation timestamp in input
6747 the count of the input frame, starting from 0.
6749 @item NB_CONSUMED_SAMPLES
6750 the number of consumed samples, not including the current frame (only
6754 the number of samples in the current frame (only audio)
6760 the PTS of the first frame
6763 the time in seconds of the first frame
6766 tell if the current frame is interlaced
6769 the time in seconds of the current frame
6775 original position in the file of the frame, or undefined if undefined
6776 for the current frame
6782 previous input time in seconds
6788 previous output time in seconds
6791 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6795 wallclock (RTC) time at the start of the movie in microseconds
6798 @subsection Examples
6802 Start counting PTS from zero
6808 Apply fast motion effect:
6814 Apply slow motion effect:
6820 Set fixed rate of 25 frames per second:
6826 Set fixed rate 25 fps with some jitter:
6828 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6832 Apply an offset of 10 seconds to the input PTS:
6838 Generate timestamps from a "live source" and rebase onto the current timebase:
6840 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6846 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6847 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6848 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6849 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6851 The filter also has a video output (see the @var{video} option) with a real
6852 time graph to observe the loudness evolution. The graphic contains the logged
6853 message mentioned above, so it is not printed anymore when this option is set,
6854 unless the verbose logging is set. The main graphing area contains the
6855 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6856 the momentary loudness (400 milliseconds).
6858 More information about the Loudness Recommendation EBU R128 on
6859 @url{http://tech.ebu.ch/loudness}.
6861 The filter accepts the following options:
6866 Activate the video output. The audio stream is passed unchanged whether this
6867 option is set or no. The video stream will be the first output stream if
6868 activated. Default is @code{0}.
6871 Set the video size. This option is for video only. Default and minimum
6872 resolution is @code{640x480}.
6875 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6876 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6877 other integer value between this range is allowed.
6880 Set metadata injection. If set to @code{1}, the audio input will be segmented
6881 into 100ms output frames, each of them containing various loudness information
6882 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6884 Default is @code{0}.
6887 Force the frame logging level.
6889 Available values are:
6892 information logging level
6894 verbose logging level
6897 By default, the logging level is set to @var{info}. If the @option{video} or
6898 the @option{metadata} options are set, it switches to @var{verbose}.
6901 @subsection Examples
6905 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6907 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6911 Run an analysis with @command{ffmpeg}:
6913 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6917 @section settb, asettb
6919 Set the timebase to use for the output frames timestamps.
6920 It is mainly useful for testing timebase configuration.
6922 This filter accepts the following options:
6927 The expression which is evaluated into the output timebase.
6931 The value for @option{tb} is an arithmetic expression representing a
6932 rational. The expression can contain the constants "AVTB" (the default
6933 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6934 audio only). Default value is "intb".
6936 @subsection Examples
6940 Set the timebase to 1/25:
6946 Set the timebase to 1/10:
6952 Set the timebase to 1001/1000:
6958 Set the timebase to 2*intb:
6964 Set the default timebase value:
6972 Concatenate audio and video streams, joining them together one after the
6975 The filter works on segments of synchronized video and audio streams. All
6976 segments must have the same number of streams of each type, and that will
6977 also be the number of streams at output.
6979 The filter accepts the following options:
6984 Set the number of segments. Default is 2.
6987 Set the number of output video streams, that is also the number of video
6988 streams in each segment. Default is 1.
6991 Set the number of output audio streams, that is also the number of video
6992 streams in each segment. Default is 0.
6995 Activate unsafe mode: do not fail if segments have a different format.
6999 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
7000 @var{a} audio outputs.
7002 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
7003 segment, in the same order as the outputs, then the inputs for the second
7006 Related streams do not always have exactly the same duration, for various
7007 reasons including codec frame size or sloppy authoring. For that reason,
7008 related synchronized streams (e.g. a video and its audio track) should be
7009 concatenated at once. The concat filter will use the duration of the longest
7010 stream in each segment (except the last one), and if necessary pad shorter
7011 audio streams with silence.
7013 For this filter to work correctly, all segments must start at timestamp 0.
7015 All corresponding streams must have the same parameters in all segments; the
7016 filtering system will automatically select a common pixel format for video
7017 streams, and a common sample format, sample rate and channel layout for
7018 audio streams, but other settings, such as resolution, must be converted
7019 explicitly by the user.
7021 Different frame rates are acceptable but will result in variable frame rate
7022 at output; be sure to configure the output file to handle it.
7024 @subsection Examples
7028 Concatenate an opening, an episode and an ending, all in bilingual version
7029 (video in stream 0, audio in streams 1 and 2):
7031 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
7032 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7033 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7034 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7038 Concatenate two parts, handling audio and video separately, using the
7039 (a)movie sources, and adjusting the resolution:
7041 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7042 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7043 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7045 Note that a desync will happen at the stitch if the audio and video streams
7046 do not have exactly the same duration in the first file.
7050 @section showspectrum
7052 Convert input audio to a video output, representing the audio frequency
7055 The filter accepts the following options:
7059 Specify the video size for the output. Default value is @code{640x512}.
7062 Specify if the spectrum should slide along the window. Default value is
7066 Specify display mode.
7068 It accepts the following values:
7071 all channels are displayed in the same row
7073 all channels are displayed in separate rows
7076 Default value is @samp{combined}.
7079 Specify display color mode.
7081 It accepts the following values:
7084 each channel is displayed in a separate color
7086 each channel is is displayed using the same color scheme
7089 Default value is @samp{channel}.
7092 Specify scale used for calculating intensity color values.
7094 It accepts the following values:
7099 square root, default
7106 Default value is @samp{sqrt}.
7109 Set saturation modifier for displayed colors. Negative values provide
7110 alternative color scheme. @code{0} is no saturation at all.
7111 Saturation must be in [-10.0, 10.0] range.
7112 Default value is @code{1}.
7115 The usage is very similar to the showwaves filter; see the examples in that
7118 @subsection Examples
7122 Large window with logarithmic color scaling:
7124 showspectrum=s=1280x480:scale=log
7128 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7130 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7131 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7137 Convert input audio to a video output, representing the samples waves.
7139 The filter accepts the following options:
7143 Specify the video size for the output. Default value is "600x240".
7148 Available values are:
7151 Draw a point for each sample.
7154 Draw a vertical line for each sample.
7157 Default value is @code{point}.
7160 Set the number of samples which are printed on the same column. A
7161 larger value will decrease the frame rate. Must be a positive
7162 integer. This option can be set only if the value for @var{rate}
7163 is not explicitly specified.
7166 Set the (approximate) output frame rate. This is done by setting the
7167 option @var{n}. Default value is "25".
7171 @subsection Examples
7175 Output the input file audio and the corresponding video representation
7178 amovie=a.mp3,asplit[out0],showwaves[out1]
7182 Create a synthetic signal and show it with showwaves, forcing a
7183 frame rate of 30 frames per second:
7185 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7189 @c man end MULTIMEDIA FILTERS
7191 @chapter Multimedia Sources
7192 @c man begin MULTIMEDIA SOURCES
7194 Below is a description of the currently available multimedia sources.
7198 This is the same as @ref{movie} source, except it selects an audio
7204 Read audio and/or video stream(s) from a movie container.
7206 This filter accepts the following options:
7210 The name of the resource to read (not necessarily a file but also a device or a
7211 stream accessed through some protocol).
7213 @item format_name, f
7214 Specifies the format assumed for the movie to read, and can be either
7215 the name of a container or an input device. If not specified the
7216 format is guessed from @var{movie_name} or by probing.
7218 @item seek_point, sp
7219 Specifies the seek point in seconds, the frames will be output
7220 starting from this seek point, the parameter is evaluated with
7221 @code{av_strtod} so the numerical value may be suffixed by an IS
7222 postfix. Default value is "0".
7225 Specifies the streams to read. Several streams can be specified,
7226 separated by "+". The source will then have as many outputs, in the
7227 same order. The syntax is explained in the ``Stream specifiers''
7228 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7229 respectively the default (best suited) video and audio stream. Default
7230 is "dv", or "da" if the filter is called as "amovie".
7232 @item stream_index, si
7233 Specifies the index of the video stream to read. If the value is -1,
7234 the best suited video stream will be automatically selected. Default
7235 value is "-1". Deprecated. If the filter is called "amovie", it will select
7236 audio instead of video.
7239 Specifies how many times to read the stream in sequence.
7240 If the value is less than 1, the stream will be read again and again.
7241 Default value is "1".
7243 Note that when the movie is looped the source timestamps are not
7244 changed, so it will generate non monotonically increasing timestamps.
7247 This filter allows to overlay a second video on top of main input of
7248 a filtergraph as shown in this graph:
7250 input -----------> deltapts0 --> overlay --> output
7253 movie --> scale--> deltapts1 -------+
7256 @subsection Examples
7260 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7261 on top of the input labelled as "in":
7263 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7264 [in] setpts=PTS-STARTPTS [main];
7265 [main][over] overlay=16:16 [out]
7269 Read from a video4linux2 device, and overlay it on top of the input
7272 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7273 [in] setpts=PTS-STARTPTS [main];
7274 [main][over] overlay=16:16 [out]
7278 Read the first video stream and the audio stream with id 0x81 from
7279 dvd.vob; the video is connected to the pad named "video" and the audio is
7280 connected to the pad named "audio":
7282 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7286 @c man end MULTIMEDIA SOURCES