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
13 input --> split ---------------------> overlay --> output
16 +-----> crop --> vflip -------+
19 This filtergraph splits the input stream in two streams, sends one
20 stream through the crop filter and the vflip filter before merging it
21 back with the other stream by overlaying it on top. You can use the
22 following command to achieve this:
25 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
28 The result will be that in output the top half of the video is mirrored
31 Filters in the same linear chain are separated by commas, and distinct
32 linear chains of filters are separated by semicolons. In our example,
33 @var{crop,vflip} are in one linear chain, @var{split} and
34 @var{overlay} are separately in another. The points where the linear
35 chains join are labelled by names enclosed in square brackets. In the
36 example, the split filter generates two outputs that are associated to
37 the labels @var{[main]} and @var{[tmp]}.
39 The stream sent to the second output of @var{split}, labelled as
40 @var{[tmp]}, is processed through the @var{crop} filter, which crops
41 away the lower half part of the video, and then vertically flipped. The
42 @var{overlay} filter takes in input the first unchanged output of the
43 split filter (which was labelled as @var{[main]}), and overlay on its
44 lower half the output generated by the @var{crop,vflip} filterchain.
46 Some filters take in input a list of parameters: they are specified
47 after the filter name and an equal sign, and are separated from each other
50 There exist so-called @var{source filters} that do not have an
51 audio/video input, and @var{sink filters} that will not have audio/video
54 @c man end FILTERING INTRODUCTION
57 @c man begin GRAPH2DOT
59 The @file{graph2dot} program included in the FFmpeg @file{tools}
60 directory can be used to parse a filtergraph description and issue a
61 corresponding textual representation in the dot language.
68 to see how to use @file{graph2dot}.
70 You can then pass the dot description to the @file{dot} program (from
71 the graphviz suite of programs) and obtain a graphical representation
74 For example the sequence of commands:
76 echo @var{GRAPH_DESCRIPTION} | \
77 tools/graph2dot -o graph.tmp && \
78 dot -Tpng graph.tmp -o graph.png && \
82 can be used to create and display an image representing the graph
83 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
84 a complete self-contained graph, with its inputs and outputs explicitly defined.
85 For example if your command line is of the form:
87 ffmpeg -i infile -vf scale=640:360 outfile
89 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
91 nullsrc,scale=640:360,nullsink
93 you may also need to set the @var{nullsrc} parameters and add a @var{format}
94 filter in order to simulate a specific input file.
98 @chapter Filtergraph description
99 @c man begin FILTERGRAPH DESCRIPTION
101 A filtergraph is a directed graph of connected filters. It can contain
102 cycles, and there can be multiple links between a pair of
103 filters. Each link has one input pad on one side connecting it to one
104 filter from which it takes its input, and one output pad on the other
105 side connecting it to the one filter accepting its output.
107 Each filter in a filtergraph is an instance of a filter class
108 registered in the application, which defines the features and the
109 number of input and output pads of the filter.
111 A filter with no input pads is called a "source", a filter with no
112 output pads is called a "sink".
114 @anchor{Filtergraph syntax}
115 @section Filtergraph syntax
117 A filtergraph can be represented using a textual representation, which is
118 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
119 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
120 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
121 @file{libavfilter/avfilter.h}.
123 A filterchain consists of a sequence of connected filters, each one
124 connected to the previous one in the sequence. A filterchain is
125 represented by a list of ","-separated filter descriptions.
127 A filtergraph consists of a sequence of filterchains. A sequence of
128 filterchains is represented by a list of ";"-separated filterchain
131 A filter is represented by a string of the form:
132 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
134 @var{filter_name} is the name of the filter class of which the
135 described filter is an instance of, and has to be the name of one of
136 the filter classes registered in the program.
137 The name of the filter class is optionally followed by a string
140 @var{arguments} is a string which contains the parameters used to
141 initialize the filter instance. It may have one of the following forms:
145 A ':'-separated list of @var{key=value} pairs.
148 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
149 the option names in the order they are declared. E.g. the @code{fade} filter
150 declares three options in this order -- @option{type}, @option{start_frame} and
151 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
152 @var{in} is assigned to the option @option{type}, @var{0} to
153 @option{start_frame} and @var{30} to @option{nb_frames}.
156 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
157 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
158 follow the same constraints order of the previous point. The following
159 @var{key=value} pairs can be set in any preferred order.
163 If the option value itself is a list of items (e.g. the @code{format} filter
164 takes a list of pixel formats), the items in the list are usually separated by
167 The list of arguments can be quoted using the character "'" as initial
168 and ending mark, and the character '\' for escaping the characters
169 within the quoted text; otherwise the argument string is considered
170 terminated when the next special character (belonging to the set
171 "[]=;,") is encountered.
173 The name and arguments of the filter are optionally preceded and
174 followed by a list of link labels.
175 A link label allows to name a link and associate it to a filter output
176 or input pad. The preceding labels @var{in_link_1}
177 ... @var{in_link_N}, are associated to the filter input pads,
178 the following labels @var{out_link_1} ... @var{out_link_M}, are
179 associated to the output pads.
181 When two link labels with the same name are found in the
182 filtergraph, a link between the corresponding input and output pad is
185 If an output pad is not labelled, it is linked by default to the first
186 unlabelled input pad of the next filter in the filterchain.
187 For example in the filterchain:
189 nullsrc, split[L1], [L2]overlay, nullsink
191 the split filter instance has two output pads, and the overlay filter
192 instance two input pads. The first output pad of split is labelled
193 "L1", the first input pad of overlay is labelled "L2", and the second
194 output pad of split is linked to the second input pad of overlay,
195 which are both unlabelled.
197 In a complete filterchain all the unlabelled filter input and output
198 pads must be connected. A filtergraph is considered valid if all the
199 filter input and output pads of all the filterchains are connected.
201 Libavfilter will automatically insert @ref{scale} filters where format
202 conversion is required. It is possible to specify swscale flags
203 for those automatically inserted scalers by prepending
204 @code{sws_flags=@var{flags};}
205 to the filtergraph description.
207 Follows a BNF description for the filtergraph syntax:
209 @var{NAME} ::= sequence of alphanumeric characters and '_'
210 @var{LINKLABEL} ::= "[" @var{NAME} "]"
211 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
212 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
213 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
214 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
215 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
218 @section Notes on filtergraph escaping
220 Some filter arguments require the use of special characters, typically
221 @code{:} to separate key=value pairs in a named options list. In this
222 case the user should perform a first level escaping when specifying
223 the filter arguments. For example, consider the following literal
224 string to be embedded in the @ref{drawtext} filter arguments:
226 this is a 'string': may contain one, or more, special characters
229 Since @code{:} is special for the filter arguments syntax, it needs to
230 be escaped, so you get:
232 text=this is a \'string\'\: may contain one, or more, special characters
235 A second level of escaping is required when embedding the filter
236 arguments in a filtergraph description, in order to escape all the
237 filtergraph special characters. Thus the example above becomes:
239 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
242 Finally an additional level of escaping may be needed when writing the
243 filtergraph description in a shell command, which depends on the
244 escaping rules of the adopted shell. For example, assuming that
245 @code{\} is special and needs to be escaped with another @code{\}, the
246 previous string will finally result in:
248 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
251 Sometimes, it might be more convenient to employ quoting in place of
252 escaping. For example the string:
254 Caesar: tu quoque, Brute, fili mi
257 Can be quoted in the filter arguments as:
259 text='Caesar: tu quoque, Brute, fili mi'
262 And finally inserted in a filtergraph like:
264 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
267 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
268 for more information about the escaping and quoting rules adopted by
271 @chapter Timeline editing
273 Some filters support a generic @option{enable} option. For the filters
274 supporting timeline editing, this option can be set to an expression which is
275 evaluated before sending a frame to the filter. If the evaluation is non-zero,
276 the filter will be enabled, otherwise the frame will be sent unchanged to the
277 next filter in the filtergraph.
279 The expression accepts the following values:
282 timestamp expressed in seconds, NAN if the input timestamp is unknown
285 sequential number of the input frame, starting from 0
288 the position in the file of the input frame, NAN if unknown
291 Additionally, these filters support an @option{enable} command that can be used
292 to re-define the expression.
294 Like any other filtering option, the @option{enable} option follows the same
297 For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3
298 minutes, and a @ref{curves} filter starting at 3 seconds:
300 smartblur = enable='between(t,10,3*60)',
301 curves = enable='gte(t,3)' : preset=cross_process
304 @c man end FILTERGRAPH DESCRIPTION
306 @chapter Audio Filters
307 @c man begin AUDIO FILTERS
309 When you configure your FFmpeg build, you can disable any of the
310 existing filters using @code{--disable-filters}.
311 The configure output will show the audio filters included in your
314 Below is a description of the currently available audio filters.
318 Convert the input audio format to the specified formats.
320 @emph{This filter is deprecated. Use @ref{aformat} instead.}
322 The filter accepts a string of the form:
323 "@var{sample_format}:@var{channel_layout}".
325 @var{sample_format} specifies the sample format, and can be a string or the
326 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
327 suffix for a planar sample format.
329 @var{channel_layout} specifies the channel layout, and can be a string
330 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
332 The special parameter "auto", signifies that the filter will
333 automatically select the output format depending on the output filter.
339 Convert input to float, planar, stereo:
345 Convert input to unsigned 8-bit, automatically select out channel layout:
353 Delay one or more audio channels.
355 Samples in delayed channel are filled with silence.
357 The filter accepts the following option:
361 Set list of delays in milliseconds for each channel separated by '|'.
362 At least one delay greater than 0 should be provided.
363 Unused delays will be silently ignored. If number of given delays is
364 smaller than number of channels all remaining channels will not be delayed.
371 Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
372 the second channel (and any other channels that may be present) unchanged.
380 Apply echoing to the input audio.
382 Echoes are reflected sound and can occur naturally amongst mountains
383 (and sometimes large buildings) when talking or shouting; digital echo
384 effects emulate this behaviour and are often used to help fill out the
385 sound of a single instrument or vocal. The time difference between the
386 original signal and the reflection is the @code{delay}, and the
387 loudness of the reflected signal is the @code{decay}.
388 Multiple echoes can have different delays and decays.
390 A description of the accepted parameters follows.
394 Set input gain of reflected signal. Default is @code{0.6}.
397 Set output gain of reflected signal. Default is @code{0.3}.
400 Set list of time intervals in milliseconds between original signal and reflections
401 separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}.
402 Default is @code{1000}.
405 Set list of loudnesses of reflected signals separated by '|'.
406 Allowed range for each @code{decay} is @code{(0 - 1.0]}.
407 Default is @code{0.5}.
414 Make it sound as if there are twice as many instruments as are actually playing:
416 aecho=0.8:0.88:60:0.4
420 If delay is very short, then it sound like a (metallic) robot playing music:
426 A longer delay will sound like an open air concert in the mountains:
428 aecho=0.8:0.9:1000:0.3
432 Same as above but with one more mountain:
434 aecho=0.8:0.9:1000|1800:0.3|0.25
440 Modify an audio signal according to the specified expressions.
442 This filter accepts one or more expressions (one for each channel),
443 which are evaluated and used to modify a corresponding audio signal.
445 This filter accepts the following options:
449 Set the '|'-separated expressions list for each separate channel. If
450 the number of input channels is greater than the number of
451 expressions, the last specified expression is used for the remaining
454 @item channel_layout, c
455 Set output channel layout. If not specified, the channel layout is
456 specified by the number of expressions. If set to @samp{same}, it will
457 use by default the same input channel layout.
460 Each expression in @var{exprs} can contain the following constants and functions:
464 channel number of the current expression
467 number of the evaluated sample, starting from 0
473 time of the evaluated sample expressed in seconds
476 @item nb_out_channels
477 input and output number of channels
480 the value of input channel with number @var{CH}
483 Note: this filter is slow. For faster processing you should use a
492 aeval=val(ch)/2:c=same
496 Invert phase of the second channel:
504 Apply fade-in/out effect to input audio.
506 A description of the accepted parameters follows.
510 Specify the effect type, can be either @code{in} for fade-in, or
511 @code{out} for a fade-out effect. Default is @code{in}.
513 @item start_sample, ss
514 Specify the number of the start sample for starting to apply the fade
515 effect. Default is 0.
518 Specify the number of samples for which the fade effect has to last. At
519 the end of the fade-in effect the output audio will have the same
520 volume as the input audio, at the end of the fade-out transition
521 the output audio will be silence. Default is 44100.
524 Specify time for starting to apply the fade effect. Default is 0.
525 The accepted syntax is:
527 [-]HH[:MM[:SS[.m...]]]
530 See also the function @code{av_parse_time()}.
531 If set this option is used instead of @var{start_sample} one.
534 Specify the duration for which the fade effect has to last. Default is 0.
535 The accepted syntax is:
537 [-]HH[:MM[:SS[.m...]]]
540 See also the function @code{av_parse_time()}.
541 At the end of the fade-in effect the output audio will have the same
542 volume as the input audio, at the end of the fade-out transition
543 the output audio will be silence.
544 If set this option is used instead of @var{nb_samples} one.
547 Set curve for fade transition.
549 It accepts the following values:
552 select triangular, linear slope (default)
554 select quarter of sine wave
556 select half of sine wave
558 select exponential sine wave
562 select inverted parabola
578 Fade in first 15 seconds of audio:
584 Fade out last 25 seconds of a 900 seconds audio:
586 afade=t=out:st=875:d=25
593 Set output format constraints for the input audio. The framework will
594 negotiate the most appropriate format to minimize conversions.
596 The filter accepts the following named parameters:
600 A '|'-separated list of requested sample formats.
603 A '|'-separated list of requested sample rates.
605 @item channel_layouts
606 A '|'-separated list of requested channel layouts.
608 See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils}
609 for the required syntax.
612 If a parameter is omitted, all values are allowed.
614 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
616 aformat=sample_fmts=u8|s16:channel_layouts=stereo
621 Apply a two-pole all-pass filter with central frequency (in Hz)
622 @var{frequency}, and filter-width @var{width}.
623 An all-pass filter changes the audio's frequency to phase relationship
624 without changing its frequency to amplitude relationship.
626 The filter accepts the following options:
633 Set method to specify band-width of filter.
646 Specify the band-width of a filter in width_type units.
651 Merge two or more audio streams into a single multi-channel stream.
653 The filter accepts the following options:
658 Set the number of inputs. Default is 2.
662 If the channel layouts of the inputs are disjoint, and therefore compatible,
663 the channel layout of the output will be set accordingly and the channels
664 will be reordered as necessary. If the channel layouts of the inputs are not
665 disjoint, the output will have all the channels of the first input then all
666 the channels of the second input, in that order, and the channel layout of
667 the output will be the default value corresponding to the total number of
670 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
671 is FC+BL+BR, then the output will be in 5.1, with the channels in the
672 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
673 first input, b1 is the first channel of the second input).
675 On the other hand, if both input are in stereo, the output channels will be
676 in the default order: a1, a2, b1, b2, and the channel layout will be
677 arbitrarily set to 4.0, which may or may not be the expected value.
679 All inputs must have the same sample rate, and format.
681 If inputs do not have the same duration, the output will stop with the
688 Merge two mono files into a stereo stream:
690 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
694 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
696 ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
702 Mixes multiple audio inputs into a single output.
706 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
708 will mix 3 input audio streams to a single output with the same duration as the
709 first input and a dropout transition time of 3 seconds.
711 The filter accepts the following named parameters:
715 Number of inputs. If unspecified, it defaults to 2.
718 How to determine the end-of-stream.
722 Duration of longest input. (default)
725 Duration of shortest input.
728 Duration of first input.
732 @item dropout_transition
733 Transition time, in seconds, for volume renormalization when an input
734 stream ends. The default value is 2 seconds.
740 Pass the audio source unchanged to the output.
744 Pad the end of a audio stream with silence, this can be used together with
745 -shortest to extend audio streams to the same length as the video stream.
748 Add a phasing effect to the input audio.
750 A phaser filter creates series of peaks and troughs in the frequency spectrum.
751 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
753 A description of the accepted parameters follows.
757 Set input gain. Default is 0.4.
760 Set output gain. Default is 0.74
763 Set delay in milliseconds. Default is 3.0.
766 Set decay. Default is 0.4.
769 Set modulation speed in Hz. Default is 0.5.
772 Set modulation type. Default is triangular.
774 It accepts the following values:
784 Resample the input audio to the specified parameters, using the
785 libswresample library. If none are specified then the filter will
786 automatically convert between its input and output.
788 This filter is also able to stretch/squeeze the audio data to make it match
789 the timestamps or to inject silence / cut out audio to make it match the
790 timestamps, do a combination of both or do neither.
792 The filter accepts the syntax
793 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
794 expresses a sample rate and @var{resampler_options} is a list of
795 @var{key}=@var{value} pairs, separated by ":". See the
796 ffmpeg-resampler manual for the complete list of supported options.
802 Resample the input audio to 44100Hz:
808 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
809 samples per second compensation:
815 @section asetnsamples
817 Set the number of samples per each output audio frame.
819 The last output packet may contain a different number of samples, as
820 the filter will flush all the remaining samples when the input audio
823 The filter accepts the following options:
827 @item nb_out_samples, n
828 Set the number of frames per each output audio frame. The number is
829 intended as the number of samples @emph{per each channel}.
830 Default value is 1024.
833 If set to 1, the filter will pad the last audio frame with zeroes, so
834 that the last frame will contain the same number of samples as the
835 previous ones. Default value is 1.
838 For example, to set the number of per-frame samples to 1234 and
839 disable padding for the last frame, use:
841 asetnsamples=n=1234:p=0
846 Set the sample rate without altering the PCM data.
847 This will result in a change of speed and pitch.
849 The filter accepts the following options:
853 Set the output sample rate. Default is 44100 Hz.
858 Show a line containing various information for each input audio frame.
859 The input audio is not modified.
861 The shown line contains a sequence of key/value pairs of the form
862 @var{key}:@var{value}.
864 A description of each shown parameter follows:
868 sequential number of the input frame, starting from 0
871 Presentation timestamp of the input frame, in time base units; the time base
872 depends on the filter input pad, and is usually 1/@var{sample_rate}.
875 presentation timestamp of the input frame in seconds
878 position of the frame in the input stream, -1 if this information in
879 unavailable and/or meaningless (for example in case of synthetic audio)
888 sample rate for the audio frame
891 number of samples (per channel) in the frame
894 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
895 the data is treated as if all the planes were concatenated.
897 @item plane_checksums
898 A list of Adler-32 checksums for each data plane.
903 Display time domain statistical information about the audio channels.
904 Statistics are calculated and displayed for each audio channel and,
905 where applicable, an overall figure is also given.
907 The filter accepts the following option:
910 Short window length in seconds, used for peak and trough RMS measurement.
911 Default is @code{0.05} (50 miliseconds). Allowed range is @code{[0.1 - 10]}.
914 A description of each shown parameter follows:
918 Mean amplitude displacement from zero.
921 Minimal sample level.
924 Maximal sample level.
928 Standard peak and RMS level measured in dBFS.
932 Peak and trough values for RMS level measured over a short window.
935 Standard ratio of peak to RMS level (note: not in dB).
938 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
939 (i.e. either @var{Min level} or @var{Max level}).
942 Number of occasions (not the number of samples) that the signal attained either
943 @var{Min level} or @var{Max level}.
948 Forward two audio streams and control the order the buffers are forwarded.
950 The filter accepts the following options:
954 Set the expression deciding which stream should be
955 forwarded next: if the result is negative, the first stream is forwarded; if
956 the result is positive or zero, the second stream is forwarded. It can use
957 the following variables:
961 number of buffers forwarded so far on each stream
963 number of samples forwarded so far on each stream
965 current timestamp of each stream
968 The default value is @code{t1-t2}, which means to always forward the stream
969 that has a smaller timestamp.
974 Stress-test @code{amerge} by randomly sending buffers on the wrong
975 input, while avoiding too much of a desynchronization:
977 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
978 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
984 Synchronize audio data with timestamps by squeezing/stretching it and/or
985 dropping samples/adding silence when needed.
987 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
989 The filter accepts the following named parameters:
993 Enable stretching/squeezing the data to make it match the timestamps. Disabled
994 by default. When disabled, time gaps are covered with silence.
997 Minimum difference between timestamps and audio data (in seconds) to trigger
998 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
999 this filter, try setting this parameter to 0.
1002 Maximum compensation in samples per second. Relevant only with compensate=1.
1006 Assume the first pts should be this value. The time base is 1 / sample rate.
1007 This allows for padding/trimming at the start of stream. By default, no
1008 assumption is made about the first frame's expected pts, so no padding or
1009 trimming is done. For example, this could be set to 0 to pad the beginning with
1010 silence if an audio stream starts after the video stream or to trim any samples
1011 with a negative pts due to encoder delay.
1019 The filter accepts exactly one parameter, the audio tempo. If not
1020 specified then the filter will assume nominal 1.0 tempo. Tempo must
1021 be in the [0.5, 2.0] range.
1023 @subsection Examples
1027 Slow down audio to 80% tempo:
1033 To speed up audio to 125% tempo:
1041 Trim the input so that the output contains one continuous subpart of the input.
1043 This filter accepts the following options:
1046 Specify time of the start of the kept section, i.e. the audio sample
1047 with the timestamp @var{start} will be the first sample in the output.
1050 Specify time of the first audio sample that will be dropped, i.e. the
1051 audio sample immediately preceding the one with the timestamp @var{end} will be
1052 the last sample in the output.
1055 Same as @var{start}, except this option sets the start timestamp in samples
1059 Same as @var{end}, except this option sets the end timestamp in samples instead
1063 Specify maximum duration of the output.
1066 Number of the first sample that should be passed to output.
1069 Number of the first sample that should be dropped.
1072 @option{start}, @option{end}, @option{duration} are expressed as time
1073 duration specifications, check the "Time duration" section in the
1074 ffmpeg-utils manual.
1076 Note that the first two sets of the start/end options and the @option{duration}
1077 option look at the frame timestamp, while the _sample options simply count the
1078 samples that pass through the filter. So start/end_pts and start/end_sample will
1079 give different results when the timestamps are wrong, inexact or do not start at
1080 zero. Also note that this filter does not modify the timestamps. If you wish
1081 that the output timestamps start at zero, insert the asetpts filter after the
1084 If multiple start or end options are set, this filter tries to be greedy and
1085 keep all samples that match at least one of the specified constraints. To keep
1086 only the part that matches all the constraints at once, chain multiple atrim
1089 The defaults are such that all the input is kept. So it is possible to set e.g.
1090 just the end values to keep everything before the specified time.
1095 drop everything except the second minute of input
1097 ffmpeg -i INPUT -af atrim=60:120
1101 keep only the first 1000 samples
1103 ffmpeg -i INPUT -af atrim=end_sample=1000
1110 Apply a two-pole Butterworth band-pass filter with central
1111 frequency @var{frequency}, and (3dB-point) band-width width.
1112 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1113 instead of the default: constant 0dB peak gain.
1114 The filter roll off at 6dB per octave (20dB per decade).
1116 The filter accepts the following options:
1120 Set the filter's central frequency. Default is @code{3000}.
1123 Constant skirt gain if set to 1. Defaults to 0.
1126 Set method to specify band-width of filter.
1139 Specify the band-width of a filter in width_type units.
1144 Apply a two-pole Butterworth band-reject filter with central
1145 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1146 The filter roll off at 6dB per octave (20dB per decade).
1148 The filter accepts the following options:
1152 Set the filter's central frequency. Default is @code{3000}.
1155 Set method to specify band-width of filter.
1168 Specify the band-width of a filter in width_type units.
1173 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1174 shelving filter with a response similar to that of a standard
1175 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1177 The filter accepts the following options:
1181 Give the gain at 0 Hz. Its useful range is about -20
1182 (for a large cut) to +20 (for a large boost).
1183 Beware of clipping when using a positive gain.
1186 Set the filter's central frequency and so can be used
1187 to extend or reduce the frequency range to be boosted or cut.
1188 The default value is @code{100} Hz.
1191 Set method to specify band-width of filter.
1204 Determine how steep is the filter's shelf transition.
1209 Apply a biquad IIR filter with the given coefficients.
1210 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1211 are the numerator and denominator coefficients respectively.
1215 Remap input channels to new locations.
1217 This filter accepts the following named parameters:
1219 @item channel_layout
1220 Channel layout of the output stream.
1223 Map channels from input to output. The argument is a '|'-separated list of
1224 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1225 @var{in_channel} form. @var{in_channel} can be either the name of the input
1226 channel (e.g. FL for front left) or its index in the input channel layout.
1227 @var{out_channel} is the name of the output channel or its index in the output
1228 channel layout. If @var{out_channel} is not given then it is implicitly an
1229 index, starting with zero and increasing by one for each mapping.
1232 If no mapping is present, the filter will implicitly map input channels to
1233 output channels preserving index.
1235 For example, assuming a 5.1+downmix input MOV file
1237 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1239 will create an output WAV file tagged as stereo from the downmix channels of
1242 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1244 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1247 @section channelsplit
1249 Split each channel in input audio stream into a separate output stream.
1251 This filter accepts the following named parameters:
1253 @item channel_layout
1254 Channel layout of the input stream. Default is "stereo".
1257 For example, assuming a stereo input MP3 file
1259 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1261 will create an output Matroska file with two audio streams, one containing only
1262 the left channel and the other the right channel.
1264 To split a 5.1 WAV file into per-channel files
1266 ffmpeg -i in.wav -filter_complex
1267 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1268 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1269 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1275 Compress or expand audio dynamic range.
1277 A description of the accepted options follows.
1282 Set list of times in seconds for each channel over which the instantaneous
1283 level of the input signal is averaged to determine its volume.
1284 @option{attacks} refers to increase of volume and @option{decays} refers
1285 to decrease of volume.
1286 For most situations, the attack time (response to the audio getting louder)
1287 should be shorter than the decay time because the human ear is more sensitive
1288 to sudden loud audio than sudden soft audio.
1289 Typical value for attack is @code{0.3} seconds and for decay @code{0.8}
1293 Set list of points for transfer function, specified in dB relative to maximum
1294 possible signal amplitude.
1295 Each key points list need to be defined using the following syntax:
1296 @code{x0/y0 x1/y1 x2/y2 ...}.
1298 The input values must be in strictly increasing order but the transfer
1299 function does not have to be monotonically rising.
1300 The point @code{0/0} is assumed but may be overridden (by @code{0/out-dBn}).
1301 Typical values for the transfer function are @code{-70/-70 -60/-20}.
1304 Set amount for which the points at where adjacent line segments on the
1305 transfer function meet will be rounded. Defaults is @code{0.01}.
1308 Set additional gain in dB to be applied at all points on the transfer function
1309 and allows easy adjustment of the overall gain.
1310 Default is @code{0}.
1313 Set initial volume in dB to be assumed for each channel when filtering starts.
1314 This permits the user to supply a nominal level initially, so that,
1315 for example, a very large gain is not applied to initial signal levels before
1316 the companding has begun to operate. A typical value for audio which is
1317 initially quiet is -90 dB. Default is @code{0}.
1320 Set delay in seconds. Default is @code{0}. The input audio
1321 is analysed immediately, but audio is delayed before being fed to the
1322 volume adjuster. Specifying a delay approximately equal to the attack/decay
1323 times allows the filter to effectively operate in predictive rather than
1327 @subsection Examples
1330 Make music with both quiet and loud passages suitable for listening
1331 in a noisy environment:
1333 compand=.3 .3:1 1:-90/-60 -60/-40 -40/-30 -20/-20:6:0:-90:0.2
1337 Noise-gate for when the noise is at a lower level than the signal:
1339 compand=.1 .1:.2 .2:-900/-900 -50.1/-900 -50/-50:.01:0:-90:.1
1343 Here is another noise-gate, this time for when the noise is at a higher level
1344 than the signal (making it, in some ways, similar to squelch):
1346 compand=.1 .1:.1 .1:-45.1/-45.1 -45/-900 0/-900:.01:45:-90:.1
1352 Make audio easier to listen to on headphones.
1354 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1355 so that when listened to on headphones the stereo image is moved from
1356 inside your head (standard for headphones) to outside and in front of
1357 the listener (standard for speakers).
1363 Apply a two-pole peaking equalisation (EQ) filter. With this
1364 filter, the signal-level at and around a selected frequency can
1365 be increased or decreased, whilst (unlike bandpass and bandreject
1366 filters) that at all other frequencies is unchanged.
1368 In order to produce complex equalisation curves, this filter can
1369 be given several times, each with a different central frequency.
1371 The filter accepts the following options:
1375 Set the filter's central frequency in Hz.
1378 Set method to specify band-width of filter.
1391 Specify the band-width of a filter in width_type units.
1394 Set the required gain or attenuation in dB.
1395 Beware of clipping when using a positive gain.
1398 @subsection Examples
1401 Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
1403 equalizer=f=1000:width_type=h:width=200:g=-10
1407 Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
1409 equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
1415 Apply a high-pass filter with 3dB point frequency.
1416 The filter can be either single-pole, or double-pole (the default).
1417 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1419 The filter accepts the following options:
1423 Set frequency in Hz. Default is 3000.
1426 Set number of poles. Default is 2.
1429 Set method to specify band-width of filter.
1442 Specify the band-width of a filter in width_type units.
1443 Applies only to double-pole filter.
1444 The default is 0.707q and gives a Butterworth response.
1449 Join multiple input streams into one multi-channel stream.
1451 The filter accepts the following named parameters:
1455 Number of input streams. Defaults to 2.
1457 @item channel_layout
1458 Desired output channel layout. Defaults to stereo.
1461 Map channels from inputs to output. The argument is a '|'-separated list of
1462 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1463 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1464 can be either the name of the input channel (e.g. FL for front left) or its
1465 index in the specified input stream. @var{out_channel} is the name of the output
1469 The filter will attempt to guess the mappings when those are not specified
1470 explicitly. It does so by first trying to find an unused matching input channel
1471 and if that fails it picks the first unused input channel.
1473 E.g. to join 3 inputs (with properly set channel layouts)
1475 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1478 To build a 5.1 output from 6 single-channel streams:
1480 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1481 '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'
1487 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
1489 To enable compilation of this filter you need to configure FFmpeg with
1490 @code{--enable-ladspa}.
1494 Specifies the name of LADSPA plugin library to load. If the environment
1495 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
1496 each one of the directories specified by the colon separated list in
1497 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
1498 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
1499 @file{/usr/lib/ladspa/}.
1502 Specifies the plugin within the library. Some libraries contain only
1503 one plugin, but others contain many of them. If this is not set filter
1504 will list all available plugins within the specified library.
1507 Set the '|' separated list of controls which are zero or more floating point
1508 values that determine the behavior of the loaded plugin (for example delay,
1510 Controls need to be defined using the following syntax:
1511 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
1512 @var{valuei} is the value set on the @var{i}-th control.
1513 If @option{controls} is set to @code{help}, all available controls and
1514 their valid ranges are printed.
1516 @item sample_rate, s
1517 Specify the sample rate, default to 44100. Only used if plugin have
1521 Set the number of samples per channel per each output frame, default
1522 is 1024. Only used if plugin have zero inputs.
1525 Set the minimum duration of the sourced audio. See the function
1526 @code{av_parse_time()} for the accepted format, also check the "Time duration"
1527 section in the ffmpeg-utils manual.
1528 Note that the resulting duration may be greater than the specified duration,
1529 as the generated audio is always cut at the end of a complete frame.
1530 If not specified, or the expressed duration is negative, the audio is
1531 supposed to be generated forever.
1532 Only used if plugin have zero inputs.
1536 @subsection Examples
1540 List all available plugins within amp (LADSPA example plugin) library:
1546 List all available controls and their valid ranges for @code{vcf_notch}
1547 plugin from @code{VCF} library:
1549 ladspa=f=vcf:p=vcf_notch:c=help
1553 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
1556 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
1560 Add reverberation to the audio using TAP-plugins
1561 (Tom's Audio Processing plugins):
1563 ladspa=file=tap_reverb:tap_reverb
1567 Generate white noise, with 0.2 amplitude:
1569 ladspa=file=cmt:noise_source_white:c=c0=.2
1573 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
1574 @code{C* Audio Plugin Suite} (CAPS) library:
1576 ladspa=file=caps:Click:c=c1=20'
1580 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
1582 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
1586 @subsection Commands
1588 This filter supports the following commands:
1591 Modify the @var{N}-th control value.
1593 If the specified value is not valid, it is ignored and prior one is kept.
1598 Apply a low-pass filter with 3dB point frequency.
1599 The filter can be either single-pole or double-pole (the default).
1600 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1602 The filter accepts the following options:
1606 Set frequency in Hz. Default is 500.
1609 Set number of poles. Default is 2.
1612 Set method to specify band-width of filter.
1625 Specify the band-width of a filter in width_type units.
1626 Applies only to double-pole filter.
1627 The default is 0.707q and gives a Butterworth response.
1632 Mix channels with specific gain levels. The filter accepts the output
1633 channel layout followed by a set of channels definitions.
1635 This filter is also designed to remap efficiently the channels of an audio
1638 The filter accepts parameters of the form:
1639 "@var{l}:@var{outdef}:@var{outdef}:..."
1643 output channel layout or number of channels
1646 output channel specification, of the form:
1647 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1650 output channel to define, either a channel name (FL, FR, etc.) or a channel
1651 number (c0, c1, etc.)
1654 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1657 input channel to use, see out_name for details; it is not possible to mix
1658 named and numbered input channels
1661 If the `=' in a channel specification is replaced by `<', then the gains for
1662 that specification will be renormalized so that the total is 1, thus
1663 avoiding clipping noise.
1665 @subsection Mixing examples
1667 For example, if you want to down-mix from stereo to mono, but with a bigger
1668 factor for the left channel:
1670 pan=1:c0=0.9*c0+0.1*c1
1673 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1674 7-channels surround:
1676 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1679 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1680 that should be preferred (see "-ac" option) unless you have very specific
1683 @subsection Remapping examples
1685 The channel remapping will be effective if, and only if:
1688 @item gain coefficients are zeroes or ones,
1689 @item only one input per channel output,
1692 If all these conditions are satisfied, the filter will notify the user ("Pure
1693 channel mapping detected"), and use an optimized and lossless method to do the
1696 For example, if you have a 5.1 source and want a stereo audio stream by
1697 dropping the extra channels:
1699 pan="stereo: c0=FL : c1=FR"
1702 Given the same source, you can also switch front left and front right channels
1703 and keep the input channel layout:
1705 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1708 If the input is a stereo audio stream, you can mute the front left channel (and
1709 still keep the stereo channel layout) with:
1714 Still with a stereo audio stream input, you can copy the right channel in both
1715 front left and right:
1717 pan="stereo: c0=FR : c1=FR"
1722 ReplayGain scanner filter. This filter takes an audio stream as an input and
1723 outputs it unchanged.
1724 At end of filtering it displays @code{track_gain} and @code{track_peak}.
1728 Convert the audio sample format, sample rate and channel layout. This filter is
1729 not meant to be used directly.
1731 @section silencedetect
1733 Detect silence in an audio stream.
1735 This filter logs a message when it detects that the input audio volume is less
1736 or equal to a noise tolerance value for a duration greater or equal to the
1737 minimum detected noise duration.
1739 The printed times and duration are expressed in seconds.
1741 The filter accepts the following options:
1745 Set silence duration until notification (default is 2 seconds).
1748 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1749 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1752 @subsection Examples
1756 Detect 5 seconds of silence with -50dB noise tolerance:
1758 silencedetect=n=-50dB:d=5
1762 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1763 tolerance in @file{silence.mp3}:
1765 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
1771 Boost or cut treble (upper) frequencies of the audio using a two-pole
1772 shelving filter with a response similar to that of a standard
1773 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1775 The filter accepts the following options:
1779 Give the gain at whichever is the lower of ~22 kHz and the
1780 Nyquist frequency. Its useful range is about -20 (for a large cut)
1781 to +20 (for a large boost). Beware of clipping when using a positive gain.
1784 Set the filter's central frequency and so can be used
1785 to extend or reduce the frequency range to be boosted or cut.
1786 The default value is @code{3000} Hz.
1789 Set method to specify band-width of filter.
1802 Determine how steep is the filter's shelf transition.
1807 Adjust the input audio volume.
1809 The filter accepts the following options:
1814 Set audio volume expression.
1816 Output values are clipped to the maximum value.
1818 The output audio volume is given by the relation:
1820 @var{output_volume} = @var{volume} * @var{input_volume}
1823 Default value for @var{volume} is "1.0".
1826 Set the mathematical precision.
1828 This determines which input sample formats will be allowed, which affects the
1829 precision of the volume scaling.
1833 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1835 32-bit floating-point; limits input sample format to FLT. (default)
1837 64-bit floating-point; limits input sample format to DBL.
1841 Set when the volume expression is evaluated.
1843 It accepts the following values:
1846 only evaluate expression once during the filter initialization, or
1847 when the @samp{volume} command is sent
1850 evaluate expression for each incoming frame
1853 Default value is @samp{once}.
1856 The volume expression can contain the following parameters.
1860 frame number (starting at zero)
1863 @item nb_consumed_samples
1864 number of samples consumed by the filter
1866 number of samples in the current frame
1868 original frame position in the file
1874 PTS at start of stream
1876 time at start of stream
1882 last set volume value
1885 Note that when @option{eval} is set to @samp{once} only the
1886 @var{sample_rate} and @var{tb} variables are available, all other
1887 variables will evaluate to NAN.
1889 @subsection Commands
1891 This filter supports the following commands:
1894 Modify the volume expression.
1895 The command accepts the same syntax of the corresponding option.
1897 If the specified expression is not valid, it is kept at its current
1901 @subsection Examples
1905 Halve the input audio volume:
1909 volume=volume=-6.0206dB
1912 In all the above example the named key for @option{volume} can be
1913 omitted, for example like in:
1919 Increase input audio power by 6 decibels using fixed-point precision:
1921 volume=volume=6dB:precision=fixed
1925 Fade volume after time 10 with an annihilation period of 5 seconds:
1927 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
1931 @section volumedetect
1933 Detect the volume of the input video.
1935 The filter has no parameters. The input is not modified. Statistics about
1936 the volume will be printed in the log when the input stream end is reached.
1938 In particular it will show the mean volume (root mean square), maximum
1939 volume (on a per-sample basis), and the beginning of a histogram of the
1940 registered volume values (from the maximum value to a cumulated 1/1000 of
1943 All volumes are in decibels relative to the maximum PCM value.
1945 @subsection Examples
1947 Here is an excerpt of the output:
1949 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1950 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1951 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1952 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1953 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1954 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1955 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1956 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1957 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1963 The mean square energy is approximately -27 dB, or 10^-2.7.
1965 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1967 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1970 In other words, raising the volume by +4 dB does not cause any clipping,
1971 raising it by +5 dB causes clipping for 6 samples, etc.
1973 @c man end AUDIO FILTERS
1975 @chapter Audio Sources
1976 @c man begin AUDIO SOURCES
1978 Below is a description of the currently available audio sources.
1982 Buffer audio frames, and make them available to the filter chain.
1984 This source is mainly intended for a programmatic use, in particular
1985 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1987 It accepts the following named parameters:
1992 Timebase which will be used for timestamps of submitted frames. It must be
1993 either a floating-point number or in @var{numerator}/@var{denominator} form.
1996 The sample rate of the incoming audio buffers.
1999 The sample format of the incoming audio buffers.
2000 Either a sample format name or its corresponging integer representation from
2001 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
2003 @item channel_layout
2004 The channel layout of the incoming audio buffers.
2005 Either a channel layout name from channel_layout_map in
2006 @file{libavutil/channel_layout.c} or its corresponding integer representation
2007 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
2010 The number of channels of the incoming audio buffers.
2011 If both @var{channels} and @var{channel_layout} are specified, then they
2016 @subsection Examples
2019 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
2022 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
2023 Since the sample format with name "s16p" corresponds to the number
2024 6 and the "stereo" channel layout corresponds to the value 0x3, this is
2027 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
2032 Generate an audio signal specified by an expression.
2034 This source accepts in input one or more expressions (one for each
2035 channel), which are evaluated and used to generate a corresponding
2038 This source accepts the following options:
2042 Set the '|'-separated expressions list for each separate channel. In case the
2043 @option{channel_layout} option is not specified, the selected channel layout
2044 depends on the number of provided expressions. Otherwise the last
2045 specified expression is applied to the remaining output channels.
2047 @item channel_layout, c
2048 Set the channel layout. The number of channels in the specified layout
2049 must be equal to the number of specified expressions.
2052 Set the minimum duration of the sourced audio. See the function
2053 @code{av_parse_time()} for the accepted format.
2054 Note that the resulting duration may be greater than the specified
2055 duration, as the generated audio is always cut at the end of a
2058 If not specified, or the expressed duration is negative, the audio is
2059 supposed to be generated forever.
2062 Set the number of samples per channel per each output frame,
2065 @item sample_rate, s
2066 Specify the sample rate, default to 44100.
2069 Each expression in @var{exprs} can contain the following constants:
2073 number of the evaluated sample, starting from 0
2076 time of the evaluated sample expressed in seconds, starting from 0
2083 @subsection Examples
2093 Generate a sin signal with frequency of 440 Hz, set sample rate to
2096 aevalsrc="sin(440*2*PI*t):s=8000"
2100 Generate a two channels signal, specify the channel layout (Front
2101 Center + Back Center) explicitly:
2103 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
2107 Generate white noise:
2109 aevalsrc="-2+random(0)"
2113 Generate an amplitude modulated signal:
2115 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
2119 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
2121 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
2128 Null audio source, return unprocessed audio frames. It is mainly useful
2129 as a template and to be employed in analysis / debugging tools, or as
2130 the source for filters which ignore the input data (for example the sox
2133 This source accepts the following options:
2137 @item channel_layout, cl
2139 Specify the channel layout, and can be either an integer or a string
2140 representing a channel layout. The default value of @var{channel_layout}
2143 Check the channel_layout_map definition in
2144 @file{libavutil/channel_layout.c} for the mapping between strings and
2145 channel layout values.
2147 @item sample_rate, r
2148 Specify the sample rate, and defaults to 44100.
2151 Set the number of samples per requested frames.
2155 @subsection Examples
2159 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
2161 anullsrc=r=48000:cl=4
2165 Do the same operation with a more obvious syntax:
2167 anullsrc=r=48000:cl=mono
2171 All the parameters need to be explicitly defined.
2175 Synthesize a voice utterance using the libflite library.
2177 To enable compilation of this filter you need to configure FFmpeg with
2178 @code{--enable-libflite}.
2180 Note that the flite library is not thread-safe.
2182 The filter accepts the following options:
2187 If set to 1, list the names of the available voices and exit
2188 immediately. Default value is 0.
2191 Set the maximum number of samples per frame. Default value is 512.
2194 Set the filename containing the text to speak.
2197 Set the text to speak.
2200 Set the voice to use for the speech synthesis. Default value is
2201 @code{kal}. See also the @var{list_voices} option.
2204 @subsection Examples
2208 Read from file @file{speech.txt}, and synthetize the text using the
2209 standard flite voice:
2211 flite=textfile=speech.txt
2215 Read the specified text selecting the @code{slt} voice:
2217 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2221 Input text to ffmpeg:
2223 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2227 Make @file{ffplay} speak the specified text, using @code{flite} and
2228 the @code{lavfi} device:
2230 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
2234 For more information about libflite, check:
2235 @url{http://www.speech.cs.cmu.edu/flite/}
2239 Generate an audio signal made of a sine wave with amplitude 1/8.
2241 The audio signal is bit-exact.
2243 The filter accepts the following options:
2248 Set the carrier frequency. Default is 440 Hz.
2250 @item beep_factor, b
2251 Enable a periodic beep every second with frequency @var{beep_factor} times
2252 the carrier frequency. Default is 0, meaning the beep is disabled.
2254 @item sample_rate, r
2255 Specify the sample rate, default is 44100.
2258 Specify the duration of the generated audio stream.
2260 @item samples_per_frame
2261 Set the number of samples per output frame, default is 1024.
2264 @subsection Examples
2269 Generate a simple 440 Hz sine wave:
2275 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
2279 sine=frequency=220:beep_factor=4:duration=5
2284 @c man end AUDIO SOURCES
2286 @chapter Audio Sinks
2287 @c man begin AUDIO SINKS
2289 Below is a description of the currently available audio sinks.
2291 @section abuffersink
2293 Buffer audio frames, and make them available to the end of filter chain.
2295 This sink is mainly intended for programmatic use, in particular
2296 through the interface defined in @file{libavfilter/buffersink.h}
2297 or the options system.
2299 It accepts a pointer to an AVABufferSinkContext structure, which
2300 defines the incoming buffers' formats, to be passed as the opaque
2301 parameter to @code{avfilter_init_filter} for initialization.
2305 Null audio sink, do absolutely nothing with the input audio. It is
2306 mainly useful as a template and to be employed in analysis / debugging
2309 @c man end AUDIO SINKS
2311 @chapter Video Filters
2312 @c man begin VIDEO FILTERS
2314 When you configure your FFmpeg build, you can disable any of the
2315 existing filters using @code{--disable-filters}.
2316 The configure output will show the video filters included in your
2319 Below is a description of the currently available video filters.
2321 @section alphaextract
2323 Extract the alpha component from the input as a grayscale video. This
2324 is especially useful with the @var{alphamerge} filter.
2328 Add or replace the alpha component of the primary input with the
2329 grayscale value of a second input. This is intended for use with
2330 @var{alphaextract} to allow the transmission or storage of frame
2331 sequences that have alpha in a format that doesn't support an alpha
2334 For example, to reconstruct full frames from a normal YUV-encoded video
2335 and a separate video created with @var{alphaextract}, you might use:
2337 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
2340 Since this filter is designed for reconstruction, it operates on frame
2341 sequences without considering timestamps, and terminates when either
2342 input reaches end of stream. This will cause problems if your encoding
2343 pipeline drops frames. If you're trying to apply an image as an
2344 overlay to a video stream, consider the @var{overlay} filter instead.
2348 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
2349 and libavformat to work. On the other hand, it is limited to ASS (Advanced
2350 Substation Alpha) subtitles files.
2354 Compute the bounding box for the non-black pixels in the input frame
2357 This filter computes the bounding box containing all the pixels with a
2358 luminance value greater than the minimum allowed value.
2359 The parameters describing the bounding box are printed on the filter
2362 The filter accepts the following option:
2366 Set the minimal luminance value. Default is @code{16}.
2369 @section blackdetect
2371 Detect video intervals that are (almost) completely black. Can be
2372 useful to detect chapter transitions, commercials, or invalid
2373 recordings. Output lines contains the time for the start, end and
2374 duration of the detected black interval expressed in seconds.
2376 In order to display the output lines, you need to set the loglevel at
2377 least to the AV_LOG_INFO value.
2379 The filter accepts the following options:
2382 @item black_min_duration, d
2383 Set the minimum detected black duration expressed in seconds. It must
2384 be a non-negative floating point number.
2386 Default value is 2.0.
2388 @item picture_black_ratio_th, pic_th
2389 Set the threshold for considering a picture "black".
2390 Express the minimum value for the ratio:
2392 @var{nb_black_pixels} / @var{nb_pixels}
2395 for which a picture is considered black.
2396 Default value is 0.98.
2398 @item pixel_black_th, pix_th
2399 Set the threshold for considering a pixel "black".
2401 The threshold expresses the maximum pixel luminance value for which a
2402 pixel is considered "black". The provided value is scaled according to
2403 the following equation:
2405 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
2408 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
2409 the input video format, the range is [0-255] for YUV full-range
2410 formats and [16-235] for YUV non full-range formats.
2412 Default value is 0.10.
2415 The following example sets the maximum pixel threshold to the minimum
2416 value, and detects only black intervals of 2 or more seconds:
2418 blackdetect=d=2:pix_th=0.00
2423 Detect frames that are (almost) completely black. Can be useful to
2424 detect chapter transitions or commercials. Output lines consist of
2425 the frame number of the detected frame, the percentage of blackness,
2426 the position in the file if known or -1 and the timestamp in seconds.
2428 In order to display the output lines, you need to set the loglevel at
2429 least to the AV_LOG_INFO value.
2431 The filter accepts the following options:
2436 Set the percentage of the pixels that have to be below the threshold, defaults
2439 @item threshold, thresh
2440 Set the threshold below which a pixel value is considered black, defaults to
2447 Blend two video frames into each other.
2449 It takes two input streams and outputs one stream, the first input is the
2450 "top" layer and second input is "bottom" layer.
2451 Output terminates when shortest input terminates.
2453 A description of the accepted options follows.
2461 Set blend mode for specific pixel component or all pixel components in case
2462 of @var{all_mode}. Default value is @code{normal}.
2464 Available values for component modes are:
2497 Set blend opacity for specific pixel component or all pixel components in case
2498 of @var{all_opacity}. Only used in combination with pixel component blend modes.
2505 Set blend expression for specific pixel component or all pixel components in case
2506 of @var{all_expr}. Note that related mode options will be ignored if those are set.
2508 The expressions can use the following variables:
2512 The sequential number of the filtered frame, starting from @code{0}.
2516 the coordinates of the current sample
2520 the width and height of currently filtered plane
2524 Width and height scale depending on the currently filtered plane. It is the
2525 ratio between the corresponding luma plane number of pixels and the current
2526 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2527 @code{0.5,0.5} for chroma planes.
2530 Time of the current frame, expressed in seconds.
2533 Value of pixel component at current location for first video frame (top layer).
2536 Value of pixel component at current location for second video frame (bottom layer).
2540 Force termination when the shortest input terminates. Default is @code{0}.
2542 Continue applying the last bottom frame after the end of the stream. A value of
2543 @code{0} disable the filter after the last frame of the bottom layer is reached.
2544 Default is @code{1}.
2547 @subsection Examples
2551 Apply transition from bottom layer to top layer in first 10 seconds:
2553 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2557 Apply 1x1 checkerboard effect:
2559 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2563 Apply uncover left effect:
2565 blend=all_expr='if(gte(N*SW+X,W),A,B)'
2569 Apply uncover down effect:
2571 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
2575 Apply uncover up-left effect:
2577 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
2583 Apply boxblur algorithm to the input video.
2585 The filter accepts the following options:
2589 @item luma_radius, lr
2590 @item luma_power, lp
2591 @item chroma_radius, cr
2592 @item chroma_power, cp
2593 @item alpha_radius, ar
2594 @item alpha_power, ap
2598 A description of the accepted options follows.
2601 @item luma_radius, lr
2602 @item chroma_radius, cr
2603 @item alpha_radius, ar
2604 Set an expression for the box radius in pixels used for blurring the
2605 corresponding input plane.
2607 The radius value must be a non-negative number, and must not be
2608 greater than the value of the expression @code{min(w,h)/2} for the
2609 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2612 Default value for @option{luma_radius} is "2". If not specified,
2613 @option{chroma_radius} and @option{alpha_radius} default to the
2614 corresponding value set for @option{luma_radius}.
2616 The expressions can contain the following constants:
2620 the input width and height in pixels
2624 the input chroma image width and height in pixels
2628 horizontal and vertical chroma subsample values. For example for the
2629 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2632 @item luma_power, lp
2633 @item chroma_power, cp
2634 @item alpha_power, ap
2635 Specify how many times the boxblur filter is applied to the
2636 corresponding plane.
2638 Default value for @option{luma_power} is 2. If not specified,
2639 @option{chroma_power} and @option{alpha_power} default to the
2640 corresponding value set for @option{luma_power}.
2642 A value of 0 will disable the effect.
2645 @subsection Examples
2649 Apply a boxblur filter with luma, chroma, and alpha radius
2652 boxblur=luma_radius=2:luma_power=1
2657 Set luma radius to 2, alpha and chroma radius to 0:
2659 boxblur=2:1:cr=0:ar=0
2663 Set luma and chroma radius to a fraction of the video dimension:
2665 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2669 @section colorbalance
2670 Modify intensity of primary colors (red, green and blue) of input frames.
2672 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
2673 regions for the red-cyan, green-magenta or blue-yellow balance.
2675 A positive adjustment value shifts the balance towards the primary color, a negative
2676 value towards the complementary color.
2678 The filter accepts the following options:
2684 Adjust red, green and blue shadows (darkest pixels).
2689 Adjust red, green and blue midtones (medium pixels).
2694 Adjust red, green and blue highlights (brightest pixels).
2696 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
2699 @subsection Examples
2703 Add red color cast to shadows:
2709 @section colorchannelmixer
2711 Adjust video input frames by re-mixing color channels.
2713 This filter modifies a color channel by adding the values associated to
2714 the other channels of the same pixels. For example if the value to
2715 modify is red, the output value will be:
2717 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
2720 The filter accepts the following options:
2727 Adjust contribution of input red, green, blue and alpha channels for output red channel.
2728 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
2734 Adjust contribution of input red, green, blue and alpha channels for output green channel.
2735 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
2741 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
2742 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
2748 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
2749 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
2751 Allowed ranges for options are @code{[-2.0, 2.0]}.
2754 @subsection Examples
2758 Convert source to grayscale:
2760 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
2763 Simulate sepia tones:
2765 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
2769 @section colormatrix
2771 Convert color matrix.
2773 The filter accepts the following options:
2778 Specify the source and destination color matrix. Both values must be
2781 The accepted values are:
2797 For example to convert from BT.601 to SMPTE-240M, use the command:
2799 colormatrix=bt601:smpte240m
2804 Copy the input source unchanged to the output. Mainly useful for
2809 Crop the input video to given dimensions.
2811 The filter accepts the following options:
2815 Width of the output video. It defaults to @code{iw}.
2816 This expression is evaluated only once during the filter
2820 Height of the output video. It defaults to @code{ih}.
2821 This expression is evaluated only once during the filter
2825 Horizontal position, in the input video, of the left edge of the output video.
2826 It defaults to @code{(in_w-out_w)/2}.
2827 This expression is evaluated per-frame.
2830 Vertical position, in the input video, of the top edge of the output video.
2831 It defaults to @code{(in_h-out_h)/2}.
2832 This expression is evaluated per-frame.
2835 If set to 1 will force the output display aspect ratio
2836 to be the same of the input, by changing the output sample aspect
2837 ratio. It defaults to 0.
2840 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2841 expressions containing the following constants:
2846 the computed values for @var{x} and @var{y}. They are evaluated for
2851 the input width and height
2855 same as @var{in_w} and @var{in_h}
2859 the output (cropped) width and height
2863 same as @var{out_w} and @var{out_h}
2866 same as @var{iw} / @var{ih}
2869 input sample aspect ratio
2872 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2876 horizontal and vertical chroma subsample values. For example for the
2877 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2880 the number of input frame, starting from 0
2883 the position in the file of the input frame, NAN if unknown
2886 timestamp expressed in seconds, NAN if the input timestamp is unknown
2890 The expression for @var{out_w} may depend on the value of @var{out_h},
2891 and the expression for @var{out_h} may depend on @var{out_w}, but they
2892 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2893 evaluated after @var{out_w} and @var{out_h}.
2895 The @var{x} and @var{y} parameters specify the expressions for the
2896 position of the top-left corner of the output (non-cropped) area. They
2897 are evaluated for each frame. If the evaluated value is not valid, it
2898 is approximated to the nearest valid value.
2900 The expression for @var{x} may depend on @var{y}, and the expression
2901 for @var{y} may depend on @var{x}.
2903 @subsection Examples
2907 Crop area with size 100x100 at position (12,34).
2912 Using named options, the example above becomes:
2914 crop=w=100:h=100:x=12:y=34
2918 Crop the central input area with size 100x100:
2924 Crop the central input area with size 2/3 of the input video:
2926 crop=2/3*in_w:2/3*in_h
2930 Crop the input video central square:
2937 Delimit the rectangle with the top-left corner placed at position
2938 100:100 and the right-bottom corner corresponding to the right-bottom
2939 corner of the input image:
2941 crop=in_w-100:in_h-100:100:100
2945 Crop 10 pixels from the left and right borders, and 20 pixels from
2946 the top and bottom borders
2948 crop=in_w-2*10:in_h-2*20
2952 Keep only the bottom right quarter of the input image:
2954 crop=in_w/2:in_h/2:in_w/2:in_h/2
2958 Crop height for getting Greek harmony:
2960 crop=in_w:1/PHI*in_w
2964 Appply trembling effect:
2966 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)
2970 Apply erratic camera effect depending on timestamp:
2972 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)"
2976 Set x depending on the value of y:
2978 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2984 Auto-detect crop size.
2986 Calculate necessary cropping parameters and prints the recommended
2987 parameters through the logging system. The detected dimensions
2988 correspond to the non-black area of the input video.
2990 The filter accepts the following options:
2995 Set higher black value threshold, which can be optionally specified
2996 from nothing (0) to everything (255). An intensity value greater
2997 to the set value is considered non-black. Default value is 24.
3000 Set the value for which the width/height should be divisible by. The
3001 offset is automatically adjusted to center the video. Use 2 to get
3002 only even dimensions (needed for 4:2:2 video). 16 is best when
3003 encoding to most video codecs. Default value is 16.
3005 @item reset_count, reset
3006 Set the counter that determines after how many frames cropdetect will
3007 reset the previously detected largest video area and start over to
3008 detect the current optimal crop area. Default value is 0.
3010 This can be useful when channel logos distort the video area. 0
3011 indicates never reset and return the largest area encountered during
3018 Apply color adjustments using curves.
3020 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
3021 component (red, green and blue) has its values defined by @var{N} key points
3022 tied from each other using a smooth curve. The x-axis represents the pixel
3023 values from the input frame, and the y-axis the new pixel values to be set for
3026 By default, a component curve is defined by the two points @var{(0;0)} and
3027 @var{(1;1)}. This creates a straight line where each original pixel value is
3028 "adjusted" to its own value, which means no change to the image.
3030 The filter allows you to redefine these two points and add some more. A new
3031 curve (using a natural cubic spline interpolation) will be define to pass
3032 smoothly through all these new coordinates. The new defined points needs to be
3033 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
3034 be in the @var{[0;1]} interval. If the computed curves happened to go outside
3035 the vector spaces, the values will be clipped accordingly.
3037 If there is no key point defined in @code{x=0}, the filter will automatically
3038 insert a @var{(0;0)} point. In the same way, if there is no key point defined
3039 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
3041 The filter accepts the following options:
3045 Select one of the available color presets. This option can be used in addition
3046 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
3047 options takes priority on the preset values.
3048 Available presets are:
3051 @item color_negative
3054 @item increase_contrast
3056 @item linear_contrast
3057 @item medium_contrast
3059 @item strong_contrast
3062 Default is @code{none}.
3064 Set the master key points. These points will define a second pass mapping. It
3065 is sometimes called a "luminance" or "value" mapping. It can be used with
3066 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
3067 post-processing LUT.
3069 Set the key points for the red component.
3071 Set the key points for the green component.
3073 Set the key points for the blue component.
3075 Set the key points for all components (not including master).
3076 Can be used in addition to the other key points component
3077 options. In this case, the unset component(s) will fallback on this
3078 @option{all} setting.
3080 Specify a Photoshop curves file (@code{.asv}) to import the settings from.
3083 To avoid some filtergraph syntax conflicts, each key points list need to be
3084 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
3086 @subsection Examples
3090 Increase slightly the middle level of blue:
3092 curves=blue='0.5/0.58'
3098 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
3100 Here we obtain the following coordinates for each components:
3103 @code{(0;0.11) (0.42;0.51) (1;0.95)}
3105 @code{(0;0) (0.50;0.48) (1;1)}
3107 @code{(0;0.22) (0.49;0.44) (1;0.80)}
3111 The previous example can also be achieved with the associated built-in preset:
3113 curves=preset=vintage
3123 Use a Photoshop preset and redefine the points of the green component:
3125 curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53'
3131 Denoise frames using 2D DCT (frequency domain filtering).
3133 This filter is not designed for real time and can be extremely slow.
3135 The filter accepts the following options:
3139 Set the noise sigma constant.
3141 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
3142 coefficient (absolute value) below this threshold with be dropped.
3144 If you need a more advanced filtering, see @option{expr}.
3146 Default is @code{0}.
3149 Set number overlapping pixels for each block. Each block is of size
3150 @code{16x16}. Since the filter can be slow, you may want to reduce this value,
3151 at the cost of a less effective filter and the risk of various artefacts.
3153 If the overlapping value doesn't allow to process the whole input width or
3154 height, a warning will be displayed and according borders won't be denoised.
3156 Default value is @code{15}.
3159 Set the coefficient factor expression.
3161 For each coefficient of a DCT block, this expression will be evaluated as a
3162 multiplier value for the coefficient.
3164 If this is option is set, the @option{sigma} option will be ignored.
3166 The absolute value of the coefficient can be accessed through the @var{c}
3170 @subsection Examples
3172 Apply a denoise with a @option{sigma} of @code{4.5}:
3177 The same operation can be achieved using the expression system:
3179 dctdnoiz=e='gte(c, 4.5*3)'
3185 Drop duplicated frames at regular intervals.
3187 The filter accepts the following options:
3191 Set the number of frames from which one will be dropped. Setting this to
3192 @var{N} means one frame in every batch of @var{N} frames will be dropped.
3193 Default is @code{5}.
3196 Set the threshold for duplicate detection. If the difference metric for a frame
3197 is less than or equal to this value, then it is declared as duplicate. Default
3201 Set scene change threshold. Default is @code{15}.
3205 Set the size of the x and y-axis blocks used during metric calculations.
3206 Larger blocks give better noise suppression, but also give worse detection of
3207 small movements. Must be a power of two. Default is @code{32}.
3210 Mark main input as a pre-processed input and activate clean source input
3211 stream. This allows the input to be pre-processed with various filters to help
3212 the metrics calculation while keeping the frame selection lossless. When set to
3213 @code{1}, the first stream is for the pre-processed input, and the second
3214 stream is the clean source from where the kept frames are chosen. Default is
3218 Set whether or not chroma is considered in the metric calculations. Default is
3224 Suppress a TV station logo by a simple interpolation of the surrounding
3225 pixels. Just set a rectangle covering the logo and watch it disappear
3226 (and sometimes something even uglier appear - your mileage may vary).
3228 This filter accepts the following options:
3233 Specify the top left corner coordinates of the logo. They must be
3238 Specify the width and height of the logo to clear. They must be
3242 Specify the thickness of the fuzzy edge of the rectangle (added to
3243 @var{w} and @var{h}). The default value is 4.
3246 When set to 1, a green rectangle is drawn on the screen to simplify
3247 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
3248 The default value is 0.
3250 The rectangle is drawn on the outermost pixels which will be (partly)
3251 replaced with interpolated values. The values of the next pixels
3252 immediately outside this rectangle in each direction will be used to
3253 compute the interpolated pixel values inside the rectangle.
3257 @subsection Examples
3261 Set a rectangle covering the area with top left corner coordinates 0,0
3262 and size 100x77, setting a band of size 10:
3264 delogo=x=0:y=0:w=100:h=77:band=10
3271 Attempt to fix small changes in horizontal and/or vertical shift. This
3272 filter helps remove camera shake from hand-holding a camera, bumping a
3273 tripod, moving on a vehicle, etc.
3275 The filter accepts the following options:
3283 Specify a rectangular area where to limit the search for motion
3285 If desired the search for motion vectors can be limited to a
3286 rectangular area of the frame defined by its top left corner, width
3287 and height. These parameters have the same meaning as the drawbox
3288 filter which can be used to visualise the position of the bounding
3291 This is useful when simultaneous movement of subjects within the frame
3292 might be confused for camera motion by the motion vector search.
3294 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
3295 then the full frame is used. This allows later options to be set
3296 without specifying the bounding box for the motion vector search.
3298 Default - search the whole frame.
3302 Specify the maximum extent of movement in x and y directions in the
3303 range 0-64 pixels. Default 16.
3306 Specify how to generate pixels to fill blanks at the edge of the
3307 frame. Available values are:
3310 Fill zeroes at blank locations
3312 Original image at blank locations
3314 Extruded edge value at blank locations
3316 Mirrored edge at blank locations
3318 Default value is @samp{mirror}.
3321 Specify the blocksize to use for motion search. Range 4-128 pixels,
3325 Specify the contrast threshold for blocks. Only blocks with more than
3326 the specified contrast (difference between darkest and lightest
3327 pixels) will be considered. Range 1-255, default 125.
3330 Specify the search strategy. Available values are:
3333 Set exhaustive search
3335 Set less exhaustive search.
3337 Default value is @samp{exhaustive}.
3340 If set then a detailed log of the motion search is written to the
3344 If set to 1, specify using OpenCL capabilities, only available if
3345 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
3351 Draw a colored box on the input image.
3353 This filter accepts the following options:
3358 The expressions which specify the top left corner coordinates of the box. Default to 0.
3362 The expressions which specify the width and height of the box, if 0 they are interpreted as
3363 the input width and height. Default to 0.
3366 Specify the color of the box to write. For the general syntax of this option,
3367 check the "Color" section in the ffmpeg-utils manual. If the special
3368 value @code{invert} is used, the box edge color is the same as the
3369 video with inverted luma.
3372 The expression which sets the thickness of the box edge. Default value is @code{3}.
3374 See below for the list of accepted constants.
3377 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3378 following constants:
3382 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3386 horizontal and vertical chroma subsample values. For example for the
3387 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3391 The input width and height.
3394 The input sample aspect ratio.
3398 The x and y offset coordinates where the box is drawn.
3402 The width and height of the drawn box.
3405 The thickness of the drawn box.
3407 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3408 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3412 @subsection Examples
3416 Draw a black box around the edge of the input image:
3422 Draw a box with color red and an opacity of 50%:
3424 drawbox=10:20:200:60:red@@0.5
3427 The previous example can be specified as:
3429 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
3433 Fill the box with pink color:
3435 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
3439 Draw a 2-pixel red 2.40:1 mask:
3441 drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red
3447 Draw a grid on the input image.
3449 This filter accepts the following options:
3454 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
3458 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
3459 input width and height, respectively, minus @code{thickness}, so image gets
3460 framed. Default to 0.
3463 Specify the color of the grid. For the general syntax of this option,
3464 check the "Color" section in the ffmpeg-utils manual. If the special
3465 value @code{invert} is used, the grid color is the same as the
3466 video with inverted luma.
3469 The expression which sets the thickness of the grid line. Default value is @code{1}.
3471 See below for the list of accepted constants.
3474 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3475 following constants:
3479 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3483 horizontal and vertical chroma subsample values. For example for the
3484 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3488 The input grid cell width and height.
3491 The input sample aspect ratio.
3495 The x and y coordinates of some point of grid intersection (meant to configure offset).
3499 The width and height of the drawn cell.
3502 The thickness of the drawn cell.
3504 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3505 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3509 @subsection Examples
3513 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
3515 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
3519 Draw a white 3x3 grid with an opacity of 50%:
3521 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
3528 Draw text string or text from specified file on top of video using the
3529 libfreetype library.
3531 To enable compilation of this filter you need to configure FFmpeg with
3532 @code{--enable-libfreetype}.
3536 The description of the accepted parameters follows.
3541 Used to draw a box around text using background color.
3542 Value should be either 1 (enable) or 0 (disable).
3543 The default value of @var{box} is 0.
3546 The color to be used for drawing box around text. For the syntax of this
3547 option, check the "Color" section in the ffmpeg-utils manual.
3549 The default value of @var{boxcolor} is "white".
3552 Set the width of the border to be drawn around the text using @var{bordercolor}.
3553 The default value of @var{borderw} is 0.
3556 Set the color to be used for drawing border around text. For the syntax of this
3557 option, check the "Color" section in the ffmpeg-utils manual.
3559 The default value of @var{bordercolor} is "black".
3562 Select how the @var{text} is expanded. Can be either @code{none},
3563 @code{strftime} (deprecated) or
3564 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
3568 If true, check and fix text coords to avoid clipping.
3571 The color to be used for drawing fonts. For the syntax of this option, check
3572 the "Color" section in the ffmpeg-utils manual.
3574 The default value of @var{fontcolor} is "black".
3577 The font file to be used for drawing text. Path must be included.
3578 This parameter is mandatory.
3581 The font size to be used for drawing text.
3582 The default value of @var{fontsize} is 16.
3585 Flags to be used for loading the fonts.
3587 The flags map the corresponding flags supported by libfreetype, and are
3588 a combination of the following values:
3595 @item vertical_layout
3596 @item force_autohint
3599 @item ignore_global_advance_width
3601 @item ignore_transform
3607 Default value is "default".
3609 For more information consult the documentation for the FT_LOAD_*
3613 The color to be used for drawing a shadow behind the drawn text. For the
3614 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
3616 The default value of @var{shadowcolor} is "black".
3620 The x and y offsets for the text shadow position with respect to the
3621 position of the text. They can be either positive or negative
3622 values. Default value for both is "0".
3625 The starting frame number for the n/frame_num variable. The default value
3629 The size in number of spaces to use for rendering the tab.
3633 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
3634 format. It can be used with or without text parameter. @var{timecode_rate}
3635 option must be specified.
3637 @item timecode_rate, rate, r
3638 Set the timecode frame rate (timecode only).
3641 The text string to be drawn. The text must be a sequence of UTF-8
3643 This parameter is mandatory if no file is specified with the parameter
3647 A text file containing text to be drawn. The text must be a sequence
3648 of UTF-8 encoded characters.
3650 This parameter is mandatory if no text string is specified with the
3651 parameter @var{text}.
3653 If both @var{text} and @var{textfile} are specified, an error is thrown.
3656 If set to 1, the @var{textfile} will be reloaded before each frame.
3657 Be sure to update it atomically, or it may be read partially, or even fail.
3661 The expressions which specify the offsets where text will be drawn
3662 within the video frame. They are relative to the top/left border of the
3665 The default value of @var{x} and @var{y} is "0".
3667 See below for the list of accepted constants and functions.
3670 The parameters for @var{x} and @var{y} are expressions containing the
3671 following constants and functions:
3675 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
3679 horizontal and vertical chroma subsample values. For example for the
3680 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3683 the height of each text line
3691 @item max_glyph_a, ascent
3692 the maximum distance from the baseline to the highest/upper grid
3693 coordinate used to place a glyph outline point, for all the rendered
3695 It is a positive value, due to the grid's orientation with the Y axis
3698 @item max_glyph_d, descent
3699 the maximum distance from the baseline to the lowest grid coordinate
3700 used to place a glyph outline point, for all the rendered glyphs.
3701 This is a negative value, due to the grid's orientation, with the Y axis
3705 maximum glyph height, that is the maximum height for all the glyphs
3706 contained in the rendered text, it is equivalent to @var{ascent} -
3710 maximum glyph width, that is the maximum width for all the glyphs
3711 contained in the rendered text
3714 the number of input frame, starting from 0
3716 @item rand(min, max)
3717 return a random number included between @var{min} and @var{max}
3720 input sample aspect ratio
3723 timestamp expressed in seconds, NAN if the input timestamp is unknown
3726 the height of the rendered text
3729 the width of the rendered text
3733 the x and y offset coordinates where the text is drawn.
3735 These parameters allow the @var{x} and @var{y} expressions to refer
3736 each other, so you can for example specify @code{y=x/dar}.
3739 If libavfilter was built with @code{--enable-fontconfig}, then
3740 @option{fontfile} can be a fontconfig pattern or omitted.
3742 @anchor{drawtext_expansion}
3743 @subsection Text expansion
3745 If @option{expansion} is set to @code{strftime},
3746 the filter recognizes strftime() sequences in the provided text and
3747 expands them accordingly. Check the documentation of strftime(). This
3748 feature is deprecated.
3750 If @option{expansion} is set to @code{none}, the text is printed verbatim.
3752 If @option{expansion} is set to @code{normal} (which is the default),
3753 the following expansion mechanism is used.
3755 The backslash character '\', followed by any character, always expands to
3756 the second character.
3758 Sequence of the form @code{%@{...@}} are expanded. The text between the
3759 braces is a function name, possibly followed by arguments separated by ':'.
3760 If the arguments contain special characters or delimiters (':' or '@}'),
3761 they should be escaped.
3763 Note that they probably must also be escaped as the value for the
3764 @option{text} option in the filter argument string and as the filter
3765 argument in the filtergraph description, and possibly also for the shell,
3766 that makes up to four levels of escaping; using a text file avoids these
3769 The following functions are available:
3774 The expression evaluation result.
3776 It must take one argument specifying the expression to be evaluated,
3777 which accepts the same constants and functions as the @var{x} and
3778 @var{y} values. Note that not all constants should be used, for
3779 example the text size is not known when evaluating the expression, so
3780 the constants @var{text_w} and @var{text_h} will have an undefined
3784 The time at which the filter is running, expressed in UTC.
3785 It can accept an argument: a strftime() format string.
3788 The time at which the filter is running, expressed in the local time zone.
3789 It can accept an argument: a strftime() format string.
3792 Frame metadata. It must take one argument specifying metadata key.
3795 The frame number, starting from 0.
3798 A 1 character description of the current picture type.
3801 The timestamp of the current frame, in seconds, with microsecond accuracy.
3805 @subsection Examples
3809 Draw "Test Text" with font FreeSerif, using the default values for the
3810 optional parameters.
3813 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
3817 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
3818 and y=50 (counting from the top-left corner of the screen), text is
3819 yellow with a red box around it. Both the text and the box have an
3823 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
3824 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
3827 Note that the double quotes are not necessary if spaces are not used
3828 within the parameter list.
3831 Show the text at the center of the video frame:
3833 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
3837 Show a text line sliding from right to left in the last row of the video
3838 frame. The file @file{LONG_LINE} is assumed to contain a single line
3841 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3845 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3847 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3851 Draw a single green letter "g", at the center of the input video.
3852 The glyph baseline is placed at half screen height.
3854 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3858 Show text for 1 second every 3 seconds:
3860 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
3864 Use fontconfig to set the font. Note that the colons need to be escaped.
3866 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3870 Print the date of a real-time encoding (see strftime(3)):
3872 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3877 For more information about libfreetype, check:
3878 @url{http://www.freetype.org/}.
3880 For more information about fontconfig, check:
3881 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3885 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3887 The filter accepts the following options:
3892 Set low and high threshold values used by the Canny thresholding
3895 The high threshold selects the "strong" edge pixels, which are then
3896 connected through 8-connectivity with the "weak" edge pixels selected
3897 by the low threshold.
3899 @var{low} and @var{high} threshold values must be choosen in the range
3900 [0,1], and @var{low} should be lesser or equal to @var{high}.
3902 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3908 edgedetect=low=0.1:high=0.4
3911 @section extractplanes
3913 Extract color channel components from input video stream into
3914 separate grayscale video streams.
3916 The filter accepts the following option:
3920 Set plane(s) to extract.
3922 Available values for planes are:
3933 Choosing planes not available in the input will result in an error.
3934 That means you cannot select @code{r}, @code{g}, @code{b} planes
3935 with @code{y}, @code{u}, @code{v} planes at same time.
3938 @subsection Examples
3942 Extract luma, u and v color channel component from input video frame
3943 into 3 grayscale outputs:
3945 ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi
3951 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
3953 For each input image, the filter will compute the optimal mapping from
3954 the input to the output given the codebook length, that is the number
3955 of distinct output colors.
3957 This filter accepts the following options.
3960 @item codebook_length, l
3961 Set codebook length. The value must be a positive integer, and
3962 represents the number of distinct output colors. Default value is 256.
3965 Set the maximum number of iterations to apply for computing the optimal
3966 mapping. The higher the value the better the result and the higher the
3967 computation time. Default value is 1.
3970 Set a random seed, must be an integer included between 0 and
3971 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
3972 will try to use a good random seed on a best effort basis.
3977 Apply fade-in/out effect to input video.
3979 This filter accepts the following options:
3983 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3985 Default is @code{in}.
3987 @item start_frame, s
3988 Specify the number of the start frame for starting to apply the fade
3989 effect. Default is 0.
3992 The number of frames for which the fade effect has to last. At the end of the
3993 fade-in effect the output video will have the same intensity as the input video,
3994 at the end of the fade-out transition the output video will be filled with the
3995 selected @option{color}.
3999 If set to 1, fade only alpha channel, if one exists on the input.
4002 @item start_time, st
4003 Specify the timestamp (in seconds) of the frame to start to apply the fade
4004 effect. If both start_frame and start_time are specified, the fade will start at
4005 whichever comes last. Default is 0.
4008 The number of seconds for which the fade effect has to last. At the end of the
4009 fade-in effect the output video will have the same intensity as the input video,
4010 at the end of the fade-out transition the output video will be filled with the
4011 selected @option{color}.
4012 If both duration and nb_frames are specified, duration is used. Default is 0.
4015 Specify the color of the fade. Default is "black".
4018 @subsection Examples
4022 Fade in first 30 frames of video:
4027 The command above is equivalent to:
4033 Fade out last 45 frames of a 200-frame video:
4036 fade=type=out:start_frame=155:nb_frames=45
4040 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
4042 fade=in:0:25, fade=out:975:25
4046 Make first 5 frames yellow, then fade in from frame 5-24:
4048 fade=in:5:20:color=yellow
4052 Fade in alpha over first 25 frames of video:
4054 fade=in:0:25:alpha=1
4058 Make first 5.5 seconds black, then fade in for 0.5 seconds:
4060 fade=t=in:st=5.5:d=0.5
4067 Extract a single field from an interlaced image using stride
4068 arithmetic to avoid wasting CPU time. The output frames are marked as
4071 The filter accepts the following options:
4075 Specify whether to extract the top (if the value is @code{0} or
4076 @code{top}) or the bottom field (if the value is @code{1} or
4082 Field matching filter for inverse telecine. It is meant to reconstruct the
4083 progressive frames from a telecined stream. The filter does not drop duplicated
4084 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
4085 followed by a decimation filter such as @ref{decimate} in the filtergraph.
4087 The separation of the field matching and the decimation is notably motivated by
4088 the possibility of inserting a de-interlacing filter fallback between the two.
4089 If the source has mixed telecined and real interlaced content,
4090 @code{fieldmatch} will not be able to match fields for the interlaced parts.
4091 But these remaining combed frames will be marked as interlaced, and thus can be
4092 de-interlaced by a later filter such as @ref{yadif} before decimation.
4094 In addition to the various configuration options, @code{fieldmatch} can take an
4095 optional second stream, activated through the @option{ppsrc} option. If
4096 enabled, the frames reconstruction will be based on the fields and frames from
4097 this second stream. This allows the first input to be pre-processed in order to
4098 help the various algorithms of the filter, while keeping the output lossless
4099 (assuming the fields are matched properly). Typically, a field-aware denoiser,
4100 or brightness/contrast adjustments can help.
4102 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
4103 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
4104 which @code{fieldmatch} is based on. While the semantic and usage are very
4105 close, some behaviour and options names can differ.
4107 The filter accepts the following options:
4111 Specify the assumed field order of the input stream. Available values are:
4115 Auto detect parity (use FFmpeg's internal parity value).
4117 Assume bottom field first.
4119 Assume top field first.
4122 Note that it is sometimes recommended not to trust the parity announced by the
4125 Default value is @var{auto}.
4128 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
4129 sense that it won't risk creating jerkiness due to duplicate frames when
4130 possible, but if there are bad edits or blended fields it will end up
4131 outputting combed frames when a good match might actually exist. On the other
4132 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
4133 but will almost always find a good frame if there is one. The other values are
4134 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
4135 jerkiness and creating duplicate frames versus finding good matches in sections
4136 with bad edits, orphaned fields, blended fields, etc.
4138 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
4140 Available values are:
4144 2-way matching (p/c)
4146 2-way matching, and trying 3rd match if still combed (p/c + n)
4148 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
4150 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
4151 still combed (p/c + n + u/b)
4153 3-way matching (p/c/n)
4155 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
4156 detected as combed (p/c/n + u/b)
4159 The parenthesis at the end indicate the matches that would be used for that
4160 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
4163 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
4166 Default value is @var{pc_n}.
4169 Mark the main input stream as a pre-processed input, and enable the secondary
4170 input stream as the clean source to pick the fields from. See the filter
4171 introduction for more details. It is similar to the @option{clip2} feature from
4174 Default value is @code{0} (disabled).
4177 Set the field to match from. It is recommended to set this to the same value as
4178 @option{order} unless you experience matching failures with that setting. In
4179 certain circumstances changing the field that is used to match from can have a
4180 large impact on matching performance. Available values are:
4184 Automatic (same value as @option{order}).
4186 Match from the bottom field.
4188 Match from the top field.
4191 Default value is @var{auto}.
4194 Set whether or not chroma is included during the match comparisons. In most
4195 cases it is recommended to leave this enabled. You should set this to @code{0}
4196 only if your clip has bad chroma problems such as heavy rainbowing or other
4197 artifacts. Setting this to @code{0} could also be used to speed things up at
4198 the cost of some accuracy.
4200 Default value is @code{1}.
4204 These define an exclusion band which excludes the lines between @option{y0} and
4205 @option{y1} from being included in the field matching decision. An exclusion
4206 band can be used to ignore subtitles, a logo, or other things that may
4207 interfere with the matching. @option{y0} sets the starting scan line and
4208 @option{y1} sets the ending line; all lines in between @option{y0} and
4209 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
4210 @option{y0} and @option{y1} to the same value will disable the feature.
4211 @option{y0} and @option{y1} defaults to @code{0}.
4214 Set the scene change detection threshold as a percentage of maximum change on
4215 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
4216 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
4217 @option{scthresh} is @code{[0.0, 100.0]}.
4219 Default value is @code{12.0}.
4222 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
4223 account the combed scores of matches when deciding what match to use as the
4224 final match. Available values are:
4228 No final matching based on combed scores.
4230 Combed scores are only used when a scene change is detected.
4232 Use combed scores all the time.
4235 Default is @var{sc}.
4238 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
4239 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
4240 Available values are:
4244 No forced calculation.
4246 Force p/c/n calculations.
4248 Force p/c/n/u/b calculations.
4251 Default value is @var{none}.
4254 This is the area combing threshold used for combed frame detection. This
4255 essentially controls how "strong" or "visible" combing must be to be detected.
4256 Larger values mean combing must be more visible and smaller values mean combing
4257 can be less visible or strong and still be detected. Valid settings are from
4258 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
4259 be detected as combed). This is basically a pixel difference value. A good
4260 range is @code{[8, 12]}.
4262 Default value is @code{9}.
4265 Sets whether or not chroma is considered in the combed frame decision. Only
4266 disable this if your source has chroma problems (rainbowing, etc.) that are
4267 causing problems for the combed frame detection with chroma enabled. Actually,
4268 using @option{chroma}=@var{0} is usually more reliable, except for the case
4269 where there is chroma only combing in the source.
4271 Default value is @code{0}.
4275 Respectively set the x-axis and y-axis size of the window used during combed
4276 frame detection. This has to do with the size of the area in which
4277 @option{combpel} pixels are required to be detected as combed for a frame to be
4278 declared combed. See the @option{combpel} parameter description for more info.
4279 Possible values are any number that is a power of 2 starting at 4 and going up
4282 Default value is @code{16}.
4285 The number of combed pixels inside any of the @option{blocky} by
4286 @option{blockx} size blocks on the frame for the frame to be detected as
4287 combed. While @option{cthresh} controls how "visible" the combing must be, this
4288 setting controls "how much" combing there must be in any localized area (a
4289 window defined by the @option{blockx} and @option{blocky} settings) on the
4290 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
4291 which point no frames will ever be detected as combed). This setting is known
4292 as @option{MI} in TFM/VFM vocabulary.
4294 Default value is @code{80}.
4297 @anchor{p/c/n/u/b meaning}
4298 @subsection p/c/n/u/b meaning
4300 @subsubsection p/c/n
4302 We assume the following telecined stream:
4305 Top fields: 1 2 2 3 4
4306 Bottom fields: 1 2 3 4 4
4309 The numbers correspond to the progressive frame the fields relate to. Here, the
4310 first two frames are progressive, the 3rd and 4th are combed, and so on.
4312 When @code{fieldmatch} is configured to run a matching from bottom
4313 (@option{field}=@var{bottom}) this is how this input stream get transformed:
4318 B 1 2 3 4 4 <-- matching reference
4327 As a result of the field matching, we can see that some frames get duplicated.
4328 To perform a complete inverse telecine, you need to rely on a decimation filter
4329 after this operation. See for instance the @ref{decimate} filter.
4331 The same operation now matching from top fields (@option{field}=@var{top})
4336 T 1 2 2 3 4 <-- matching reference
4346 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
4347 basically, they refer to the frame and field of the opposite parity:
4350 @item @var{p} matches the field of the opposite parity in the previous frame
4351 @item @var{c} matches the field of the opposite parity in the current frame
4352 @item @var{n} matches the field of the opposite parity in the next frame
4357 The @var{u} and @var{b} matching are a bit special in the sense that they match
4358 from the opposite parity flag. In the following examples, we assume that we are
4359 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
4360 'x' is placed above and below each matched fields.
4362 With bottom matching (@option{field}=@var{bottom}):
4367 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4368 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4376 With top matching (@option{field}=@var{top}):
4381 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4382 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4390 @subsection Examples
4392 Simple IVTC of a top field first telecined stream:
4394 fieldmatch=order=tff:combmatch=none, decimate
4397 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
4399 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
4404 Transform the field order of the input video.
4406 This filter accepts the following options:
4411 Output field order. Valid values are @var{tff} for top field first or @var{bff}
4412 for bottom field first.
4415 Default value is @samp{tff}.
4417 Transformation is achieved by shifting the picture content up or down
4418 by one line, and filling the remaining line with appropriate picture content.
4419 This method is consistent with most broadcast field order converters.
4421 If the input video is not flagged as being interlaced, or it is already
4422 flagged as being of the required output field order then this filter does
4423 not alter the incoming video.
4425 This filter is very useful when converting to or from PAL DV material,
4426 which is bottom field first.
4430 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
4435 Buffer input images and send them when they are requested.
4437 This filter is mainly useful when auto-inserted by the libavfilter
4440 The filter does not take parameters.
4445 Convert the input video to one of the specified pixel formats.
4446 Libavfilter will try to pick one that is supported for the input to
4449 This filter accepts the following parameters:
4453 A '|'-separated list of pixel format names, for example
4454 "pix_fmts=yuv420p|monow|rgb24".
4458 @subsection Examples
4462 Convert the input video to the format @var{yuv420p}
4464 format=pix_fmts=yuv420p
4467 Convert the input video to any of the formats in the list
4469 format=pix_fmts=yuv420p|yuv444p|yuv410p
4476 Convert the video to specified constant frame rate by duplicating or dropping
4477 frames as necessary.
4479 This filter accepts the following named parameters:
4483 Desired output frame rate. The default is @code{25}.
4488 Possible values are:
4491 zero round towards 0
4495 round towards -infinity
4497 round towards +infinity
4501 The default is @code{near}.
4504 Assume the first PTS should be the given value, in seconds. This allows for
4505 padding/trimming at the start of stream. By default, no assumption is made
4506 about the first frame's expected PTS, so no padding or trimming is done.
4507 For example, this could be set to 0 to pad the beginning with duplicates of
4508 the first frame if a video stream starts after the audio stream or to trim any
4509 frames with a negative PTS.
4513 Alternatively, the options can be specified as a flat string:
4514 @var{fps}[:@var{round}].
4516 See also the @ref{setpts} filter.
4518 @subsection Examples
4522 A typical usage in order to set the fps to 25:
4528 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
4530 fps=fps=film:round=near
4536 Pack two different video streams into a stereoscopic video, setting proper
4537 metadata on supported codecs. The two views should have the same size and
4538 framerate and processing will stop when the shorter video ends. Please note
4539 that you may conveniently adjust view properties with the @ref{scale} and
4542 This filter accepts the following named parameters:
4546 Desired packing format. Supported values are:
4551 Views are next to each other (default).
4554 Views are on top of each other.
4557 Views are packed by line.
4560 Views are eacked by column.
4563 Views are temporally interleaved.
4569 Some examples follow:
4572 # Convert left and right views into a frame sequential video.
4573 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
4575 # Convert views into a side-by-side video with the same output resolution as the input.
4576 ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
4581 Select one frame every N-th frame.
4583 This filter accepts the following option:
4586 Select frame after every @code{step} frames.
4587 Allowed values are positive integers higher than 0. Default value is @code{1}.
4593 Apply a frei0r effect to the input video.
4595 To enable compilation of this filter you need to install the frei0r
4596 header and configure FFmpeg with @code{--enable-frei0r}.
4598 This filter accepts the following options:
4603 The name to the frei0r effect to load. If the environment variable
4604 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
4605 directories specified by the colon separated list in @env{FREIOR_PATH},
4606 otherwise in the standard frei0r paths, which are in this order:
4607 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
4608 @file{/usr/lib/frei0r-1/}.
4611 A '|'-separated list of parameters to pass to the frei0r effect.
4615 A frei0r effect parameter can be a boolean (whose values are specified
4616 with "y" and "n"), a double, a color (specified by the syntax
4617 @var{R}/@var{G}/@var{B}, (@var{R}, @var{G}, and @var{B} being float
4618 numbers from 0.0 to 1.0) or by a color description specified in the "Color"
4619 section in the ffmpeg-utils manual), a position (specified by the syntax @var{X}/@var{Y},
4620 @var{X} and @var{Y} being float numbers) and a string.
4622 The number and kind of parameters depend on the loaded effect. If an
4623 effect parameter is not specified the default value is set.
4625 @subsection Examples
4629 Apply the distort0r effect, set the first two double parameters:
4631 frei0r=filter_name=distort0r:filter_params=0.5|0.01
4635 Apply the colordistance effect, take a color as first parameter:
4637 frei0r=colordistance:0.2/0.3/0.4
4638 frei0r=colordistance:violet
4639 frei0r=colordistance:0x112233
4643 Apply the perspective effect, specify the top left and top right image
4646 frei0r=perspective:0.2/0.2|0.8/0.2
4650 For more information see:
4651 @url{http://frei0r.dyne.org}
4655 The filter accepts the following options:
4659 Set the luminance expression.
4661 Set the chrominance blue expression.
4663 Set the chrominance red expression.
4665 Set the alpha expression.
4667 Set the red expression.
4669 Set the green expression.
4671 Set the blue expression.
4674 The colorspace is selected according to the specified options. If one
4675 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
4676 options is specified, the filter will automatically select a YCbCr
4677 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
4678 @option{blue_expr} options is specified, it will select an RGB
4681 If one of the chrominance expression is not defined, it falls back on the other
4682 one. If no alpha expression is specified it will evaluate to opaque value.
4683 If none of chrominance expressions are specified, they will evaluate
4684 to the luminance expression.
4686 The expressions can use the following variables and functions:
4690 The sequential number of the filtered frame, starting from @code{0}.
4694 The coordinates of the current sample.
4698 The width and height of the image.
4702 Width and height scale depending on the currently filtered plane. It is the
4703 ratio between the corresponding luma plane number of pixels and the current
4704 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4705 @code{0.5,0.5} for chroma planes.
4708 Time of the current frame, expressed in seconds.
4711 Return the value of the pixel at location (@var{x},@var{y}) of the current
4715 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
4719 Return the value of the pixel at location (@var{x},@var{y}) of the
4720 blue-difference chroma plane. Return 0 if there is no such plane.
4723 Return the value of the pixel at location (@var{x},@var{y}) of the
4724 red-difference chroma plane. Return 0 if there is no such plane.
4729 Return the value of the pixel at location (@var{x},@var{y}) of the
4730 red/green/blue component. Return 0 if there is no such component.
4733 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
4734 plane. Return 0 if there is no such plane.
4737 For functions, if @var{x} and @var{y} are outside the area, the value will be
4738 automatically clipped to the closer edge.
4740 @subsection Examples
4744 Flip the image horizontally:
4750 Generate a bidimensional sine wave, with angle @code{PI/3} and a
4751 wavelength of 100 pixels:
4753 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
4757 Generate a fancy enigmatic moving light:
4759 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
4763 Generate a quick emboss effect:
4765 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
4769 Modify RGB components depending on pixel position:
4771 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
4777 Fix the banding artifacts that are sometimes introduced into nearly flat
4778 regions by truncation to 8bit color depth.
4779 Interpolate the gradients that should go where the bands are, and
4782 This filter is designed for playback only. Do not use it prior to
4783 lossy compression, because compression tends to lose the dither and
4784 bring back the bands.
4786 This filter accepts the following options:
4791 The maximum amount by which the filter will change any one pixel. Also the
4792 threshold for detecting nearly flat regions. Acceptable values range from .51 to
4793 64, default value is 1.2, out-of-range values will be clipped to the valid
4797 The neighborhood to fit the gradient to. A larger radius makes for smoother
4798 gradients, but also prevents the filter from modifying the pixels near detailed
4799 regions. Acceptable values are 8-32, default value is 16, out-of-range values
4800 will be clipped to the valid range.
4804 Alternatively, the options can be specified as a flat string:
4805 @var{strength}[:@var{radius}]
4807 @subsection Examples
4811 Apply the filter with a @code{3.5} strength and radius of @code{8}:
4817 Specify radius, omitting the strength (which will fall-back to the default
4828 Apply a Hald CLUT to a video stream.
4830 First input is the video stream to process, and second one is the Hald CLUT.
4831 The Hald CLUT input can be a simple picture or a complete video stream.
4833 The filter accepts the following options:
4837 Force termination when the shortest input terminates. Default is @code{0}.
4839 Continue applying the last CLUT after the end of the stream. A value of
4840 @code{0} disable the filter after the last frame of the CLUT is reached.
4841 Default is @code{1}.
4844 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
4845 filters share the same internals).
4847 More information about the Hald CLUT can be found on Eskil Steenberg's website
4848 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
4850 @subsection Workflow examples
4852 @subsubsection Hald CLUT video stream
4854 Generate an identity Hald CLUT stream altered with various effects:
4856 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut
4859 Note: make sure you use a lossless codec.
4861 Then use it with @code{haldclut} to apply it on some random stream:
4863 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
4866 The Hald CLUT will be applied to the 10 first seconds (duration of
4867 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
4868 to the remaining frames of the @code{mandelbrot} stream.
4870 @subsubsection Hald CLUT with preview
4872 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
4873 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
4874 biggest possible square starting at the top left of the picture. The remaining
4875 padding pixels (bottom or right) will be ignored. This area can be used to add
4876 a preview of the Hald CLUT.
4878 Typically, the following generated Hald CLUT will be supported by the
4879 @code{haldclut} filter:
4882 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
4883 pad=iw+320 [padded_clut];
4884 smptebars=s=320x256, split [a][b];
4885 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
4886 [main][b] overlay=W-320" -frames:v 1 clut.png
4889 It contains the original and a preview of the effect of the CLUT: SMPTE color
4890 bars are displayed on the right-top, and below the same color bars processed by
4893 Then, the effect of this Hald CLUT can be visualized with:
4895 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
4900 Flip the input video horizontally.
4902 For example to horizontally flip the input video with @command{ffmpeg}:
4904 ffmpeg -i in.avi -vf "hflip" out.avi
4908 This filter applies a global color histogram equalization on a
4911 It can be used to correct video that has a compressed range of pixel
4912 intensities. The filter redistributes the pixel intensities to
4913 equalize their distribution across the intensity range. It may be
4914 viewed as an "automatically adjusting contrast filter". This filter is
4915 useful only for correcting degraded or poorly captured source
4918 The filter accepts the following options:
4922 Determine the amount of equalization to be applied. As the strength
4923 is reduced, the distribution of pixel intensities more-and-more
4924 approaches that of the input frame. The value must be a float number
4925 in the range [0,1] and defaults to 0.200.
4928 Set the maximum intensity that can generated and scale the output
4929 values appropriately. The strength should be set as desired and then
4930 the intensity can be limited if needed to avoid washing-out. The value
4931 must be a float number in the range [0,1] and defaults to 0.210.
4934 Set the antibanding level. If enabled the filter will randomly vary
4935 the luminance of output pixels by a small amount to avoid banding of
4936 the histogram. Possible values are @code{none}, @code{weak} or
4937 @code{strong}. It defaults to @code{none}.
4942 Compute and draw a color distribution histogram for the input video.
4944 The computed histogram is a representation of distribution of color components
4947 The filter accepts the following options:
4953 It accepts the following values:
4956 standard histogram that display color components distribution in an image.
4957 Displays color graph for each color component. Shows distribution
4958 of the Y, U, V, A or R, G, B components, depending on input format,
4959 in current frame. Bellow each graph is color component scale meter.
4962 chroma values in vectorscope, if brighter more such chroma values are
4963 distributed in an image.
4964 Displays chroma values (U/V color placement) in two dimensional graph
4965 (which is called a vectorscope). It can be used to read of the hue and
4966 saturation of the current frame. At a same time it is a histogram.
4967 The whiter a pixel in the vectorscope, the more pixels of the input frame
4968 correspond to that pixel (that is the more pixels have this chroma value).
4969 The V component is displayed on the horizontal (X) axis, with the leftmost
4970 side being V = 0 and the rightmost side being V = 255.
4971 The U component is displayed on the vertical (Y) axis, with the top
4972 representing U = 0 and the bottom representing U = 255.
4974 The position of a white pixel in the graph corresponds to the chroma value
4975 of a pixel of the input clip. So the graph can be used to read of the
4976 hue (color flavor) and the saturation (the dominance of the hue in the color).
4977 As the hue of a color changes, it moves around the square. At the center of
4978 the square, the saturation is zero, which means that the corresponding pixel
4979 has no color. If you increase the amount of a specific color, while leaving
4980 the other colors unchanged, the saturation increases, and you move towards
4981 the edge of the square.
4984 chroma values in vectorscope, similar as @code{color} but actual chroma values
4988 per row/column color component graph. In row mode graph in the left side represents
4989 color component value 0 and right side represents value = 255. In column mode top
4990 side represents color component value = 0 and bottom side represents value = 255.
4992 Default value is @code{levels}.
4995 Set height of level in @code{levels}. Default value is @code{200}.
4996 Allowed range is [50, 2048].
4999 Set height of color scale in @code{levels}. Default value is @code{12}.
5000 Allowed range is [0, 40].
5003 Set step for @code{waveform} mode. Smaller values are useful to find out how much
5004 of same luminance values across input rows/columns are distributed.
5005 Default value is @code{10}. Allowed range is [1, 255].
5008 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
5009 Default is @code{row}.
5011 @item waveform_mirror
5012 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
5013 means mirrored. In mirrored mode, higher values will be represented on the left
5014 side for @code{row} mode and at the top for @code{column} mode. Default is
5015 @code{0} (unmirrored).
5018 Set display mode for @code{waveform} and @code{levels}.
5019 It accepts the following values:
5022 Display separate graph for the color components side by side in
5023 @code{row} waveform mode or one below other in @code{column} waveform mode
5024 for @code{waveform} histogram mode. For @code{levels} histogram mode
5025 per color component graphs are placed one bellow other.
5027 This display mode in @code{waveform} histogram mode makes it easy to spot
5028 color casts in the highlights and shadows of an image, by comparing the
5029 contours of the top and the bottom of each waveform.
5030 Since whites, grays, and blacks are characterized by
5031 exactly equal amounts of red, green, and blue, neutral areas of the
5032 picture should display three waveforms of roughly equal width/height.
5033 If not, the correction is easy to make by making adjustments to level the
5037 Presents information that's identical to that in the @code{parade}, except
5038 that the graphs representing color components are superimposed directly
5041 This display mode in @code{waveform} histogram mode can make it easier to spot
5042 the relative differences or similarities in overlapping areas of the color
5043 components that are supposed to be identical, such as neutral whites, grays,
5046 Default is @code{parade}.
5049 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
5050 Default is @code{linear}.
5053 @subsection Examples
5058 Calculate and draw histogram:
5060 ffplay -i input -vf histogram
5068 High precision/quality 3d denoise filter. This filter aims to reduce
5069 image noise producing smooth images and making still images really
5070 still. It should enhance compressibility.
5072 It accepts the following optional parameters:
5076 a non-negative float number which specifies spatial luma strength,
5079 @item chroma_spatial
5080 a non-negative float number which specifies spatial chroma strength,
5081 defaults to 3.0*@var{luma_spatial}/4.0
5084 a float number which specifies luma temporal strength, defaults to
5085 6.0*@var{luma_spatial}/4.0
5088 a float number which specifies chroma temporal strength, defaults to
5089 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
5094 Modify the hue and/or the saturation of the input.
5096 This filter accepts the following options:
5100 Specify the hue angle as a number of degrees. It accepts an expression,
5101 and defaults to "0".
5104 Specify the saturation in the [-10,10] range. It accepts an expression and
5108 Specify the hue angle as a number of radians. It accepts an
5109 expression, and defaults to "0".
5112 Specify the brightness in the [-10,10] range. It accepts an expression and
5116 @option{h} and @option{H} are mutually exclusive, and can't be
5117 specified at the same time.
5119 The @option{b}, @option{h}, @option{H} and @option{s} option values are
5120 expressions containing the following constants:
5124 frame count of the input frame starting from 0
5127 presentation timestamp of the input frame expressed in time base units
5130 frame rate of the input video, NAN if the input frame rate is unknown
5133 timestamp expressed in seconds, NAN if the input timestamp is unknown
5136 time base of the input video
5139 @subsection Examples
5143 Set the hue to 90 degrees and the saturation to 1.0:
5149 Same command but expressing the hue in radians:
5155 Rotate hue and make the saturation swing between 0
5156 and 2 over a period of 1 second:
5158 hue="H=2*PI*t: s=sin(2*PI*t)+1"
5162 Apply a 3 seconds saturation fade-in effect starting at 0:
5167 The general fade-in expression can be written as:
5169 hue="s=min(0\, max((t-START)/DURATION\, 1))"
5173 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
5175 hue="s=max(0\, min(1\, (8-t)/3))"
5178 The general fade-out expression can be written as:
5180 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
5185 @subsection Commands
5187 This filter supports the following commands:
5193 Modify the hue and/or the saturation and/or brightness of the input video.
5194 The command accepts the same syntax of the corresponding option.
5196 If the specified expression is not valid, it is kept at its current
5202 Detect video interlacing type.
5204 This filter tries to detect if the input is interlaced or progressive,
5205 top or bottom field first.
5207 The filter accepts the following options:
5211 Set interlacing threshold.
5213 Set progressive threshold.
5218 Deinterleave or interleave fields.
5220 This filter allows to process interlaced images fields without
5221 deinterlacing them. Deinterleaving splits the input frame into 2
5222 fields (so called half pictures). Odd lines are moved to the top
5223 half of the output image, even lines to the bottom half.
5224 You can process (filter) them independently and then re-interleave them.
5226 The filter accepts the following options:
5230 @item chroma_mode, c
5232 Available values for @var{luma_mode}, @var{chroma_mode} and
5233 @var{alpha_mode} are:
5239 @item deinterleave, d
5240 Deinterleave fields, placing one above the other.
5243 Interleave fields. Reverse the effect of deinterleaving.
5245 Default value is @code{none}.
5248 @item chroma_swap, cs
5249 @item alpha_swap, as
5250 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
5255 Simple interlacing filter from progressive contents. This interleaves upper (or
5256 lower) lines from odd frames with lower (or upper) lines from even frames,
5257 halving the frame rate and preserving image height.
5260 Original Original New Frame
5261 Frame 'j' Frame 'j+1' (tff)
5262 ========== =========== ==================
5263 Line 0 --------------------> Frame 'j' Line 0
5264 Line 1 Line 1 ----> Frame 'j+1' Line 1
5265 Line 2 ---------------------> Frame 'j' Line 2
5266 Line 3 Line 3 ----> Frame 'j+1' Line 3
5268 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
5271 It accepts the following optional parameters:
5275 determines whether the interlaced frame is taken from the even (tff - default)
5276 or odd (bff) lines of the progressive frame.
5279 Enable (default) or disable the vertical lowpass filter to avoid twitter
5280 interlacing and reduce moire patterns.
5285 Deinterlace input video by applying Donald Graft's adaptive kernel
5286 deinterling. Work on interlaced parts of a video to produce
5289 The description of the accepted parameters follows.
5293 Set the threshold which affects the filter's tolerance when
5294 determining if a pixel line must be processed. It must be an integer
5295 in the range [0,255] and defaults to 10. A value of 0 will result in
5296 applying the process on every pixels.
5299 Paint pixels exceeding the threshold value to white if set to 1.
5303 Set the fields order. Swap fields if set to 1, leave fields alone if
5307 Enable additional sharpening if set to 1. Default is 0.
5310 Enable twoway sharpening if set to 1. Default is 0.
5313 @subsection Examples
5317 Apply default values:
5319 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
5323 Enable additional sharpening:
5329 Paint processed pixels in white:
5338 Apply a 3D LUT to an input video.
5340 The filter accepts the following options:
5344 Set the 3D LUT file name.
5346 Currently supported formats:
5358 Select interpolation mode.
5360 Available values are:
5364 Use values from the nearest defined point.
5366 Interpolate values using the 8 points defining a cube.
5368 Interpolate values using a tetrahedron.
5372 @section lut, lutrgb, lutyuv
5374 Compute a look-up table for binding each pixel component input value
5375 to an output value, and apply it to input video.
5377 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
5378 to an RGB input video.
5380 These filters accept the following options:
5383 set first pixel component expression
5385 set second pixel component expression
5387 set third pixel component expression
5389 set fourth pixel component expression, corresponds to the alpha component
5392 set red component expression
5394 set green component expression
5396 set blue component expression
5398 alpha component expression
5401 set Y/luminance component expression
5403 set U/Cb component expression
5405 set V/Cr component expression
5408 Each of them specifies the expression to use for computing the lookup table for
5409 the corresponding pixel component values.
5411 The exact component associated to each of the @var{c*} options depends on the
5414 The @var{lut} filter requires either YUV or RGB pixel formats in input,
5415 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
5417 The expressions can contain the following constants and functions:
5422 the input width and height
5425 input value for the pixel component
5428 the input value clipped in the @var{minval}-@var{maxval} range
5431 maximum value for the pixel component
5434 minimum value for the pixel component
5437 the negated value for the pixel component value clipped in the
5438 @var{minval}-@var{maxval} range , it corresponds to the expression
5439 "maxval-clipval+minval"
5442 the computed value in @var{val} clipped in the
5443 @var{minval}-@var{maxval} range
5445 @item gammaval(gamma)
5446 the computed gamma correction value of the pixel component value
5447 clipped in the @var{minval}-@var{maxval} range, corresponds to the
5449 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
5453 All expressions default to "val".
5455 @subsection Examples
5461 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
5462 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
5465 The above is the same as:
5467 lutrgb="r=negval:g=negval:b=negval"
5468 lutyuv="y=negval:u=negval:v=negval"
5478 Remove chroma components, turns the video into a graytone image:
5480 lutyuv="u=128:v=128"
5484 Apply a luma burning effect:
5490 Remove green and blue components:
5496 Set a constant alpha channel value on input:
5498 format=rgba,lutrgb=a="maxval-minval/2"
5502 Correct luminance gamma by a 0.5 factor:
5504 lutyuv=y=gammaval(0.5)
5508 Discard least significant bits of luma:
5510 lutyuv=y='bitand(val, 128+64+32)'
5514 @section mergeplanes
5516 Merge color channel components from several video streams.
5518 The filter accepts up to 4 input streams, and merge selected input
5519 planes to the output video.
5521 This filter accepts the following options:
5524 Set input to output plane mapping. Default is @code{0}.
5526 The mappings is specified as a bitmap. It should be specified as a
5527 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
5528 mapping for the first plane of the output stream. 'A' sets the number of
5529 the input stream to use (from 0 to 3), and 'a' the plane number of the
5530 corresponding input to use (from 0 to 3). The rest of the mappings is
5531 similar, 'Bb' describes the mapping for the output stream second
5532 plane, 'Cc' describes the mapping for the output stream third plane and
5533 'Dd' describes the mapping for the output stream fourth plane.
5536 Set output pixel format. Default is @code{yuva444p}.
5539 @subsection Examples
5543 Merge three gray video streams of same width and height into single video stream:
5545 [a0][a1][a2]mergeplanes=0x001020:yuv444p
5549 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
5551 [a0][a1]mergeplanes=0x00010210:yuva444p
5555 Swap Y and A plane in yuva444p stream:
5557 format=yuva444p,mergeplanes=0x03010200:yuva444p
5561 Swap U and V plane in yuv420p stream:
5563 format=yuv420p,mergeplanes=0x000201:yuv420p
5567 Cast a rgb24 clip to yuv444p:
5569 format=rgb24,mergeplanes=0x000102:yuv444p
5575 Apply motion-compensation deinterlacing.
5577 It needs one field per frame as input and must thus be used together
5578 with yadif=1/3 or equivalent.
5580 This filter accepts the following options:
5583 Set the deinterlacing mode.
5585 It accepts one of the following values:
5590 use iterative motion estimation
5592 like @samp{slow}, but use multiple reference frames.
5594 Default value is @samp{fast}.
5597 Set the picture field parity assumed for the input video. It must be
5598 one of the following values:
5602 assume top field first
5604 assume bottom field first
5607 Default value is @samp{bff}.
5610 Set per-block quantization parameter (QP) used by the internal
5613 Higher values should result in a smoother motion vector field but less
5614 optimal individual vectors. Default value is 1.
5619 Apply an MPlayer filter to the input video.
5621 This filter provides a wrapper around some of the filters of
5624 This wrapper is considered experimental. Some of the wrapped filters
5625 may not work properly and we may drop support for them, as they will
5626 be implemented natively into FFmpeg. Thus you should avoid
5627 depending on them when writing portable scripts.
5629 The filter accepts the parameters:
5630 @var{filter_name}[:=]@var{filter_params}
5632 @var{filter_name} is the name of a supported MPlayer filter,
5633 @var{filter_params} is a string containing the parameters accepted by
5636 The list of the currently supported filters follows:
5647 The parameter syntax and behavior for the listed filters are the same
5648 of the corresponding MPlayer filters. For detailed instructions check
5649 the "VIDEO FILTERS" section in the MPlayer manual.
5651 @subsection Examples
5655 Adjust gamma, brightness, contrast:
5661 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
5665 Drop frames that do not differ greatly from the previous frame in
5666 order to reduce frame rate.
5668 The main use of this filter is for very-low-bitrate encoding
5669 (e.g. streaming over dialup modem), but it could in theory be used for
5670 fixing movies that were inverse-telecined incorrectly.
5672 A description of the accepted options follows.
5676 Set the maximum number of consecutive frames which can be dropped (if
5677 positive), or the minimum interval between dropped frames (if
5678 negative). If the value is 0, the frame is dropped unregarding the
5679 number of previous sequentially dropped frames.
5686 Set the dropping threshold values.
5688 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
5689 represent actual pixel value differences, so a threshold of 64
5690 corresponds to 1 unit of difference for each pixel, or the same spread
5691 out differently over the block.
5693 A frame is a candidate for dropping if no 8x8 blocks differ by more
5694 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
5695 meaning the whole image) differ by more than a threshold of @option{lo}.
5697 Default value for @option{hi} is 64*12, default value for @option{lo} is
5698 64*5, and default value for @option{frac} is 0.33.
5706 This filter accepts an integer in input, if non-zero it negates the
5707 alpha component (if available). The default value in input is 0.
5711 Force libavfilter not to use any of the specified pixel formats for the
5712 input to the next filter.
5714 This filter accepts the following parameters:
5718 A '|'-separated list of pixel format names, for example
5719 "pix_fmts=yuv420p|monow|rgb24".
5723 @subsection Examples
5727 Force libavfilter to use a format different from @var{yuv420p} for the
5728 input to the vflip filter:
5730 noformat=pix_fmts=yuv420p,vflip
5734 Convert the input video to any of the formats not contained in the list:
5736 noformat=yuv420p|yuv444p|yuv410p
5742 Add noise on video input frame.
5744 The filter accepts the following options:
5752 Set noise seed for specific pixel component or all pixel components in case
5753 of @var{all_seed}. Default value is @code{123457}.
5755 @item all_strength, alls
5756 @item c0_strength, c0s
5757 @item c1_strength, c1s
5758 @item c2_strength, c2s
5759 @item c3_strength, c3s
5760 Set noise strength for specific pixel component or all pixel components in case
5761 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
5763 @item all_flags, allf
5768 Set pixel component flags or set flags for all components if @var{all_flags}.
5769 Available values for component flags are:
5772 averaged temporal noise (smoother)
5774 mix random noise with a (semi)regular pattern
5776 temporal noise (noise pattern changes between frames)
5778 uniform noise (gaussian otherwise)
5782 @subsection Examples
5784 Add temporal and uniform noise to input video:
5786 noise=alls=20:allf=t+u
5791 Pass the video source unchanged to the output.
5795 Apply video transform using libopencv.
5797 To enable this filter install libopencv library and headers and
5798 configure FFmpeg with @code{--enable-libopencv}.
5800 This filter accepts the following parameters:
5805 The name of the libopencv filter to apply.
5808 The parameters to pass to the libopencv filter. If not specified the default
5813 Refer to the official libopencv documentation for more precise
5815 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
5817 Follows the list of supported libopencv filters.
5822 Dilate an image by using a specific structuring element.
5823 This filter corresponds to the libopencv function @code{cvDilate}.
5825 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
5827 @var{struct_el} represents a structuring element, and has the syntax:
5828 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
5830 @var{cols} and @var{rows} represent the number of columns and rows of
5831 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
5832 point, and @var{shape} the shape for the structuring element, and
5833 can be one of the values "rect", "cross", "ellipse", "custom".
5835 If the value for @var{shape} is "custom", it must be followed by a
5836 string of the form "=@var{filename}". The file with name
5837 @var{filename} is assumed to represent a binary image, with each
5838 printable character corresponding to a bright pixel. When a custom
5839 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
5840 or columns and rows of the read file are assumed instead.
5842 The default value for @var{struct_el} is "3x3+0x0/rect".
5844 @var{nb_iterations} specifies the number of times the transform is
5845 applied to the image, and defaults to 1.
5847 Follow some example:
5849 # use the default values
5852 # dilate using a structuring element with a 5x5 cross, iterate two times
5853 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
5855 # read the shape from the file diamond.shape, iterate two times
5856 # the file diamond.shape may contain a pattern of characters like this:
5862 # the specified cols and rows are ignored (but not the anchor point coordinates)
5863 ocv=dilate:0x0+2x2/custom=diamond.shape|2
5868 Erode an image by using a specific structuring element.
5869 This filter corresponds to the libopencv function @code{cvErode}.
5871 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
5872 with the same syntax and semantics as the @ref{dilate} filter.
5876 Smooth the input video.
5878 The filter takes the following parameters:
5879 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
5881 @var{type} is the type of smooth filter to apply, and can be one of
5882 the following values: "blur", "blur_no_scale", "median", "gaussian",
5883 "bilateral". The default value is "gaussian".
5885 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
5886 parameters whose meanings depend on smooth type. @var{param1} and
5887 @var{param2} accept integer positive values or 0, @var{param3} and
5888 @var{param4} accept float values.
5890 The default value for @var{param1} is 3, the default value for the
5891 other parameters is 0.
5893 These parameters correspond to the parameters assigned to the
5894 libopencv function @code{cvSmooth}.
5899 Overlay one video on top of another.
5901 It takes two inputs and one output, the first input is the "main"
5902 video on which the second input is overlayed.
5904 This filter accepts the following parameters:
5906 A description of the accepted options follows.
5911 Set the expression for the x and y coordinates of the overlayed video
5912 on the main video. Default value is "0" for both expressions. In case
5913 the expression is invalid, it is set to a huge value (meaning that the
5914 overlay will not be displayed within the output visible area).
5917 Set when the expressions for @option{x}, and @option{y} are evaluated.
5919 It accepts the following values:
5922 only evaluate expressions once during the filter initialization or
5923 when a command is processed
5926 evaluate expressions for each incoming frame
5929 Default value is @samp{frame}.
5932 If set to 1, force the output to terminate when the shortest input
5933 terminates. Default value is 0.
5936 Set the format for the output video.
5938 It accepts the following values:
5950 Default value is @samp{yuv420}.
5952 @item rgb @emph{(deprecated)}
5953 If set to 1, force the filter to accept inputs in the RGB
5954 color space. Default value is 0. This option is deprecated, use
5955 @option{format} instead.
5958 If set to 1, force the filter to draw the last overlay frame over the
5959 main input until the end of the stream. A value of 0 disables this
5960 behavior. Default value is 1.
5963 The @option{x}, and @option{y} expressions can contain the following
5969 main input width and height
5973 overlay input width and height
5977 the computed values for @var{x} and @var{y}. They are evaluated for
5982 horizontal and vertical chroma subsample values of the output
5983 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
5987 the number of input frame, starting from 0
5990 the position in the file of the input frame, NAN if unknown
5993 timestamp expressed in seconds, NAN if the input timestamp is unknown
5996 Note that the @var{n}, @var{pos}, @var{t} variables are available only
5997 when evaluation is done @emph{per frame}, and will evaluate to NAN
5998 when @option{eval} is set to @samp{init}.
6000 Be aware that frames are taken from each input video in timestamp
6001 order, hence, if their initial timestamps differ, it is a good idea
6002 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
6003 have them begin in the same zero timestamp, as it does the example for
6004 the @var{movie} filter.
6006 You can chain together more overlays but you should test the
6007 efficiency of such approach.
6009 @subsection Commands
6011 This filter supports the following commands:
6015 Modify the x and y of the overlay input.
6016 The command accepts the same syntax of the corresponding option.
6018 If the specified expression is not valid, it is kept at its current
6022 @subsection Examples
6026 Draw the overlay at 10 pixels from the bottom right corner of the main
6029 overlay=main_w-overlay_w-10:main_h-overlay_h-10
6032 Using named options the example above becomes:
6034 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
6038 Insert a transparent PNG logo in the bottom left corner of the input,
6039 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
6041 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
6045 Insert 2 different transparent PNG logos (second logo on bottom
6046 right corner) using the @command{ffmpeg} tool:
6048 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
6052 Add a transparent color layer on top of the main video, @code{WxH}
6053 must specify the size of the main input to the overlay filter:
6055 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
6059 Play an original video and a filtered version (here with the deshake
6060 filter) side by side using the @command{ffplay} tool:
6062 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
6065 The above command is the same as:
6067 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
6071 Make a sliding overlay appearing from the left to the right top part of the
6072 screen starting since time 2:
6074 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
6078 Compose output by putting two input videos side to side:
6080 ffmpeg -i left.avi -i right.avi -filter_complex "
6081 nullsrc=size=200x100 [background];
6082 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
6083 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
6084 [background][left] overlay=shortest=1 [background+left];
6085 [background+left][right] overlay=shortest=1:x=100 [left+right]
6090 Chain several overlays in cascade:
6092 nullsrc=s=200x200 [bg];
6093 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
6094 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
6095 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
6096 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
6097 [in3] null, [mid2] overlay=100:100 [out0]
6104 Apply Overcomplete Wavelet denoiser.
6106 The filter accepts the following options:
6112 Larger depth values will denoise lower frequency components more, but
6113 slow down filtering.
6115 Must be an int in the range 8-16, default is @code{8}.
6117 @item luma_strength, ls
6120 Must be a double value in the range 0-1000, default is @code{1.0}.
6122 @item chroma_strength, cs
6123 Set chroma strength.
6125 Must be a double value in the range 0-1000, default is @code{1.0}.
6130 Add paddings to the input image, and place the original input at the
6131 given coordinates @var{x}, @var{y}.
6133 This filter accepts the following parameters:
6138 Specify an expression for the size of the output image with the
6139 paddings added. If the value for @var{width} or @var{height} is 0, the
6140 corresponding input size is used for the output.
6142 The @var{width} expression can reference the value set by the
6143 @var{height} expression, and vice versa.
6145 The default value of @var{width} and @var{height} is 0.
6149 Specify an expression for the offsets where to place the input image
6150 in the padded area with respect to the top/left border of the output
6153 The @var{x} expression can reference the value set by the @var{y}
6154 expression, and vice versa.
6156 The default value of @var{x} and @var{y} is 0.
6159 Specify the color of the padded area. For the syntax of this option,
6160 check the "Color" section in the ffmpeg-utils manual.
6162 The default value of @var{color} is "black".
6165 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
6166 options are expressions containing the following constants:
6171 the input video width and height
6175 same as @var{in_w} and @var{in_h}
6179 the output width and height, that is the size of the padded area as
6180 specified by the @var{width} and @var{height} expressions
6184 same as @var{out_w} and @var{out_h}
6188 x and y offsets as specified by the @var{x} and @var{y}
6189 expressions, or NAN if not yet specified
6192 same as @var{iw} / @var{ih}
6195 input sample aspect ratio
6198 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
6202 horizontal and vertical chroma subsample values. For example for the
6203 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6206 @subsection Examples
6210 Add paddings with color "violet" to the input video. Output video
6211 size is 640x480, the top-left corner of the input video is placed at
6214 pad=640:480:0:40:violet
6217 The example above is equivalent to the following command:
6219 pad=width=640:height=480:x=0:y=40:color=violet
6223 Pad the input to get an output with dimensions increased by 3/2,
6224 and put the input video at the center of the padded area:
6226 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
6230 Pad the input to get a squared output with size equal to the maximum
6231 value between the input width and height, and put the input video at
6232 the center of the padded area:
6234 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
6238 Pad the input to get a final w/h ratio of 16:9:
6240 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
6244 In case of anamorphic video, in order to set the output display aspect
6245 correctly, it is necessary to use @var{sar} in the expression,
6246 according to the relation:
6248 (ih * X / ih) * sar = output_dar
6249 X = output_dar / sar
6252 Thus the previous example needs to be modified to:
6254 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
6258 Double output size and put the input video in the bottom-right
6259 corner of the output padded area:
6261 pad="2*iw:2*ih:ow-iw:oh-ih"
6265 @section perspective
6267 Correct perspective of video not recorded perpendicular to the screen.
6269 A description of the accepted parameters follows.
6280 Set coordinates expression for top left, top right, bottom left and bottom right corners.
6281 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
6283 The expressions can use the following variables:
6288 the width and height of video frame.
6292 Set interpolation for perspective correction.
6294 It accepts the following values:
6300 Default value is @samp{linear}.
6305 Delay interlaced video by one field time so that the field order changes.
6307 The intended use is to fix PAL movies that have been captured with the
6308 opposite field order to the film-to-video transfer.
6310 A description of the accepted parameters follows.
6316 It accepts the following values:
6319 Capture field order top-first, transfer bottom-first.
6320 Filter will delay the bottom field.
6323 Capture field order bottom-first, transfer top-first.
6324 Filter will delay the top field.
6327 Capture and transfer with the same field order. This mode only exists
6328 for the documentation of the other options to refer to, but if you
6329 actually select it, the filter will faithfully do nothing.
6332 Capture field order determined automatically by field flags, transfer
6334 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
6335 basis using field flags. If no field information is available,
6336 then this works just like @samp{u}.
6339 Capture unknown or varying, transfer opposite.
6340 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
6341 analyzing the images and selecting the alternative that produces best
6342 match between the fields.
6345 Capture top-first, transfer unknown or varying.
6346 Filter selects among @samp{t} and @samp{p} using image analysis.
6349 Capture bottom-first, transfer unknown or varying.
6350 Filter selects among @samp{b} and @samp{p} using image analysis.
6353 Capture determined by field flags, transfer unknown or varying.
6354 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
6355 image analysis. If no field information is available, then this works just
6356 like @samp{U}. This is the default mode.
6359 Both capture and transfer unknown or varying.
6360 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
6364 @section pixdesctest
6366 Pixel format descriptor test filter, mainly useful for internal
6367 testing. The output video should be equal to the input video.
6371 format=monow, pixdesctest
6374 can be used to test the monowhite pixel format descriptor definition.
6378 Enable the specified chain of postprocessing subfilters using libpostproc. This
6379 library should be automatically selected with a GPL build (@code{--enable-gpl}).
6380 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
6381 Each subfilter and some options have a short and a long name that can be used
6382 interchangeably, i.e. dr/dering are the same.
6384 The filters accept the following options:
6388 Set postprocessing subfilters string.
6391 All subfilters share common options to determine their scope:
6395 Honor the quality commands for this subfilter.
6398 Do chrominance filtering, too (default).
6401 Do luminance filtering only (no chrominance).
6404 Do chrominance filtering only (no luminance).
6407 These options can be appended after the subfilter name, separated by a '|'.
6409 Available subfilters are:
6412 @item hb/hdeblock[|difference[|flatness]]
6413 Horizontal deblocking filter
6416 Difference factor where higher values mean more deblocking (default: @code{32}).
6418 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6421 @item vb/vdeblock[|difference[|flatness]]
6422 Vertical deblocking filter
6425 Difference factor where higher values mean more deblocking (default: @code{32}).
6427 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6430 @item ha/hadeblock[|difference[|flatness]]
6431 Accurate horizontal deblocking filter
6434 Difference factor where higher values mean more deblocking (default: @code{32}).
6436 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6439 @item va/vadeblock[|difference[|flatness]]
6440 Accurate vertical deblocking filter
6443 Difference factor where higher values mean more deblocking (default: @code{32}).
6445 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6449 The horizontal and vertical deblocking filters share the difference and
6450 flatness values so you cannot set different horizontal and vertical
6455 Experimental horizontal deblocking filter
6458 Experimental vertical deblocking filter
6463 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
6466 larger -> stronger filtering
6468 larger -> stronger filtering
6470 larger -> stronger filtering
6473 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
6476 Stretch luminance to @code{0-255}.
6479 @item lb/linblenddeint
6480 Linear blend deinterlacing filter that deinterlaces the given block by
6481 filtering all lines with a @code{(1 2 1)} filter.
6483 @item li/linipoldeint
6484 Linear interpolating deinterlacing filter that deinterlaces the given block by
6485 linearly interpolating every second line.
6487 @item ci/cubicipoldeint
6488 Cubic interpolating deinterlacing filter deinterlaces the given block by
6489 cubically interpolating every second line.
6491 @item md/mediandeint
6492 Median deinterlacing filter that deinterlaces the given block by applying a
6493 median filter to every second line.
6495 @item fd/ffmpegdeint
6496 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
6497 second line with a @code{(-1 4 2 4 -1)} filter.
6500 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
6501 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
6503 @item fq/forceQuant[|quantizer]
6504 Overrides the quantizer table from the input with the constant quantizer you
6512 Default pp filter combination (@code{hb|a,vb|a,dr|a})
6515 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
6518 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
6521 @subsection Examples
6525 Apply horizontal and vertical deblocking, deringing and automatic
6526 brightness/contrast:
6532 Apply default filters without brightness/contrast correction:
6538 Apply default filters and temporal denoiser:
6540 pp=default/tmpnoise|1|2|3
6544 Apply deblocking on luminance only, and switch vertical deblocking on or off
6545 automatically depending on available CPU time:
6553 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
6554 Ratio) between two input videos.
6556 This filter takes in input two input videos, the first input is
6557 considered the "main" source and is passed unchanged to the
6558 output. The second input is used as a "reference" video for computing
6561 Both video inputs must have the same resolution and pixel format for
6562 this filter to work correctly. Also it assumes that both inputs
6563 have the same number of frames, which are compared one by one.
6565 The obtained average PSNR is printed through the logging system.
6567 The filter stores the accumulated MSE (mean squared error) of each
6568 frame, and at the end of the processing it is averaged across all frames
6569 equally, and the following formula is applied to obtain the PSNR:
6572 PSNR = 10*log10(MAX^2/MSE)
6575 Where MAX is the average of the maximum values of each component of the
6578 The description of the accepted parameters follows.
6582 If specified the filter will use the named file to save the PSNR of
6583 each individual frame.
6586 The file printed if @var{stats_file} is selected, contains a sequence of
6587 key/value pairs of the form @var{key}:@var{value} for each compared
6590 A description of each shown parameter follows:
6594 sequential number of the input frame, starting from 1
6597 Mean Square Error pixel-by-pixel average difference of the compared
6598 frames, averaged over all the image components.
6600 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
6601 Mean Square Error pixel-by-pixel average difference of the compared
6602 frames for the component specified by the suffix.
6604 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
6605 Peak Signal to Noise ratio of the compared frames for the component
6606 specified by the suffix.
6611 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
6612 [main][ref] psnr="stats_file=stats.log" [out]
6615 On this example the input file being processed is compared with the
6616 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
6617 is stored in @file{stats.log}.
6621 Pulldown reversal (inverse telecine) filter, capable of handling mixed
6622 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
6625 The pullup filter is designed to take advantage of future context in making
6626 its decisions. This filter is stateless in the sense that it does not lock
6627 onto a pattern to follow, but it instead looks forward to the following
6628 fields in order to identify matches and rebuild progressive frames.
6630 To produce content with an even framerate, insert the fps filter after
6631 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
6632 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
6634 The filter accepts the following options:
6641 These options set the amount of "junk" to ignore at the left, right, top, and
6642 bottom of the image, respectively. Left and right are in units of 8 pixels,
6643 while top and bottom are in units of 2 lines.
6644 The default is 8 pixels on each side.
6647 Set the strict breaks. Setting this option to 1 will reduce the chances of
6648 filter generating an occasional mismatched frame, but it may also cause an
6649 excessive number of frames to be dropped during high motion sequences.
6650 Conversely, setting it to -1 will make filter match fields more easily.
6651 This may help processing of video where there is slight blurring between
6652 the fields, but may also cause there to be interlaced frames in the output.
6653 Default value is @code{0}.
6656 Set the metric plane to use. It accepts the following values:
6662 Use chroma blue plane.
6665 Use chroma red plane.
6668 This option may be set to use chroma plane instead of the default luma plane
6669 for doing filter's computations. This may improve accuracy on very clean
6670 source material, but more likely will decrease accuracy, especially if there
6671 is chroma noise (rainbow effect) or any grayscale video.
6672 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
6673 load and make pullup usable in realtime on slow machines.
6676 For best results (without duplicated frames in the output file) it is
6677 necessary to change the output frame rate. For example, to inverse
6678 telecine NTSC input:
6680 ffmpeg -i input -vf pullup -r 24000/1001 ...
6685 Suppress a TV station logo, using an image file to determine which
6686 pixels comprise the logo. It works by filling in the pixels that
6687 comprise the logo with neighboring pixels.
6689 The filter accepts the following options:
6693 Set the filter bitmap file, which can be any image format supported by
6694 libavformat. The width and height of the image file must match those of the
6695 video stream being processed.
6698 Pixels in the provided bitmap image with a value of zero are not
6699 considered part of the logo, non-zero pixels are considered part of
6700 the logo. If you use white (255) for the logo and black (0) for the
6701 rest, you will be safe. For making the filter bitmap, it is
6702 recommended to take a screen capture of a black frame with the logo
6703 visible, and then using a threshold filter followed by the erode
6704 filter once or twice.
6706 If needed, little splotches can be fixed manually. Remember that if
6707 logo pixels are not covered, the filter quality will be much
6708 reduced. Marking too many pixels as part of the logo does not hurt as
6709 much, but it will increase the amount of blurring needed to cover over
6710 the image and will destroy more information than necessary, and extra
6711 pixels will slow things down on a large logo.
6715 Rotate video by an arbitrary angle expressed in radians.
6717 The filter accepts the following options:
6719 A description of the optional parameters follows.
6722 Set an expression for the angle by which to rotate the input video
6723 clockwise, expressed as a number of radians. A negative value will
6724 result in a counter-clockwise rotation. By default it is set to "0".
6726 This expression is evaluated for each frame.
6729 Set the output width expression, default value is "iw".
6730 This expression is evaluated just once during configuration.
6733 Set the output height expression, default value is "ih".
6734 This expression is evaluated just once during configuration.
6737 Enable bilinear interpolation if set to 1, a value of 0 disables
6738 it. Default value is 1.
6741 Set the color used to fill the output area not covered by the rotated
6742 image. For the generalsyntax of this option, check the "Color" section in the
6743 ffmpeg-utils manual. If the special value "none" is selected then no
6744 background is printed (useful for example if the background is never shown).
6746 Default value is "black".
6749 The expressions for the angle and the output size can contain the
6750 following constants and functions:
6754 sequential number of the input frame, starting from 0. It is always NAN
6755 before the first frame is filtered.
6758 time in seconds of the input frame, it is set to 0 when the filter is
6759 configured. It is always NAN before the first frame is filtered.
6763 horizontal and vertical chroma subsample values. For example for the
6764 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6768 the input video width and heigth
6772 the output width and heigth, that is the size of the padded area as
6773 specified by the @var{width} and @var{height} expressions
6777 the minimal width/height required for completely containing the input
6778 video rotated by @var{a} radians.
6780 These are only available when computing the @option{out_w} and
6781 @option{out_h} expressions.
6784 @subsection Examples
6788 Rotate the input by PI/6 radians clockwise:
6794 Rotate the input by PI/6 radians counter-clockwise:
6800 Rotate the input by 45 degrees clockwise:
6806 Apply a constant rotation with period T, starting from an angle of PI/3:
6808 rotate=PI/3+2*PI*t/T
6812 Make the input video rotation oscillating with a period of T
6813 seconds and an amplitude of A radians:
6815 rotate=A*sin(2*PI/T*t)
6819 Rotate the video, output size is choosen so that the whole rotating
6820 input video is always completely contained in the output:
6822 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
6826 Rotate the video, reduce the output size so that no background is ever
6829 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
6833 @subsection Commands
6835 The filter supports the following commands:
6839 Set the angle expression.
6840 The command accepts the same syntax of the corresponding option.
6842 If the specified expression is not valid, it is kept at its current
6848 Apply Shape Adaptive Blur.
6850 The filter accepts the following options:
6853 @item luma_radius, lr
6854 Set luma blur filter strength, must be a value in range 0.1-4.0, default
6855 value is 1.0. A greater value will result in a more blurred image, and
6856 in slower processing.
6858 @item luma_pre_filter_radius, lpfr
6859 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
6862 @item luma_strength, ls
6863 Set luma maximum difference between pixels to still be considered, must
6864 be a value in the 0.1-100.0 range, default value is 1.0.
6866 @item chroma_radius, cr
6867 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
6868 greater value will result in a more blurred image, and in slower
6871 @item chroma_pre_filter_radius, cpfr
6872 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
6874 @item chroma_strength, cs
6875 Set chroma maximum difference between pixels to still be considered,
6876 must be a value in the 0.1-100.0 range.
6879 Each chroma option value, if not explicitly specified, is set to the
6880 corresponding luma option value.
6885 Scale (resize) the input video, using the libswscale library.
6887 The scale filter forces the output display aspect ratio to be the same
6888 of the input, by changing the output sample aspect ratio.
6890 If the input image format is different from the format requested by
6891 the next filter, the scale filter will convert the input to the
6895 The filter accepts the following options, or any of the options
6896 supported by the libswscale scaler.
6898 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
6899 the complete list of scaler options.
6904 Set the output video dimension expression. Default value is the input
6907 If the value is 0, the input width is used for the output.
6909 If one of the values is -1, the scale filter will use a value that
6910 maintains the aspect ratio of the input image, calculated from the
6911 other specified dimension. If both of them are -1, the input size is
6914 See below for the list of accepted constants for use in the dimension
6918 Set the interlacing mode. It accepts the following values:
6922 Force interlaced aware scaling.
6925 Do not apply interlaced scaling.
6928 Select interlaced aware scaling depending on whether the source frames
6929 are flagged as interlaced or not.
6932 Default value is @samp{0}.
6935 Set libswscale scaling flags. See
6936 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
6937 complete list of values. If not explictly specified the filter applies
6941 Set the video size. For the syntax of this option, check the "Video size"
6942 section in the ffmpeg-utils manual.
6944 @item in_color_matrix
6945 @item out_color_matrix
6946 Set in/output YCbCr color space type.
6948 This allows the autodetected value to be overridden as well as allows forcing
6949 a specific value used for the output and encoder.
6951 If not specified, the color space type depends on the pixel format.
6957 Choose automatically.
6960 Format conforming to International Telecommunication Union (ITU)
6961 Recommendation BT.709.
6964 Set color space conforming to the United States Federal Communications
6965 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
6968 Set color space conforming to:
6972 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
6975 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
6978 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
6983 Set color space conforming to SMPTE ST 240:1999.
6988 Set in/output YCbCr sample range.
6990 This allows the autodetected value to be overridden as well as allows forcing
6991 a specific value used for the output and encoder. If not specified, the
6992 range depends on the pixel format. Possible values:
6996 Choose automatically.
6999 Set full range (0-255 in case of 8-bit luma).
7002 Set "MPEG" range (16-235 in case of 8-bit luma).
7005 @item force_original_aspect_ratio
7006 Enable decreasing or increasing output video width or height if necessary to
7007 keep the original aspect ratio. Possible values:
7011 Scale the video as specified and disable this feature.
7014 The output video dimensions will automatically be decreased if needed.
7017 The output video dimensions will automatically be increased if needed.
7021 One useful instance of this option is that when you know a specific device's
7022 maximum allowed resolution, you can use this to limit the output video to
7023 that, while retaining the aspect ratio. For example, device A allows
7024 1280x720 playback, and your video is 1920x800. Using this option (set it to
7025 decrease) and specifying 1280x720 to the command line makes the output
7028 Please note that this is a different thing than specifying -1 for @option{w}
7029 or @option{h}, you still need to specify the output resolution for this option
7034 The values of the @option{w} and @option{h} options are expressions
7035 containing the following constants:
7040 the input width and height
7044 same as @var{in_w} and @var{in_h}
7048 the output (scaled) width and height
7052 same as @var{out_w} and @var{out_h}
7055 same as @var{iw} / @var{ih}
7058 input sample aspect ratio
7061 input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
7065 horizontal and vertical input chroma subsample values. For example for the
7066 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7070 horizontal and vertical output chroma subsample values. For example for the
7071 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7074 @subsection Examples
7078 Scale the input video to a size of 200x100:
7083 This is equivalent to:
7094 Specify a size abbreviation for the output size:
7099 which can also be written as:
7105 Scale the input to 2x:
7111 The above is the same as:
7117 Scale the input to 2x with forced interlaced scaling:
7119 scale=2*iw:2*ih:interl=1
7123 Scale the input to half size:
7129 Increase the width, and set the height to the same size:
7135 Seek for Greek harmony:
7142 Increase the height, and set the width to 3/2 of the height:
7144 scale=w=3/2*oh:h=3/5*ih
7148 Increase the size, but make the size a multiple of the chroma
7151 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
7155 Increase the width to a maximum of 500 pixels, keep the same input
7158 scale=w='min(500\, iw*3/2):h=-1'
7162 @section separatefields
7164 The @code{separatefields} takes a frame-based video input and splits
7165 each frame into its components fields, producing a new half height clip
7166 with twice the frame rate and twice the frame count.
7168 This filter use field-dominance information in frame to decide which
7169 of each pair of fields to place first in the output.
7170 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
7172 @section setdar, setsar
7174 The @code{setdar} filter sets the Display Aspect Ratio for the filter
7177 This is done by changing the specified Sample (aka Pixel) Aspect
7178 Ratio, according to the following equation:
7180 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
7183 Keep in mind that the @code{setdar} filter does not modify the pixel
7184 dimensions of the video frame. Also the display aspect ratio set by
7185 this filter may be changed by later filters in the filterchain,
7186 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
7189 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
7190 the filter output video.
7192 Note that as a consequence of the application of this filter, the
7193 output display aspect ratio will change according to the equation
7196 Keep in mind that the sample aspect ratio set by the @code{setsar}
7197 filter may be changed by later filters in the filterchain, e.g. if
7198 another "setsar" or a "setdar" filter is applied.
7200 The filters accept the following options:
7203 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
7204 Set the aspect ratio used by the filter.
7206 The parameter can be a floating point number string, an expression, or
7207 a string of the form @var{num}:@var{den}, where @var{num} and
7208 @var{den} are the numerator and denominator of the aspect ratio. If
7209 the parameter is not specified, it is assumed the value "0".
7210 In case the form "@var{num}:@var{den}" is used, the @code{:} character
7214 Set the maximum integer value to use for expressing numerator and
7215 denominator when reducing the expressed aspect ratio to a rational.
7216 Default value is @code{100}.
7220 The parameter @var{sar} is an expression containing
7221 the following constants:
7225 the corresponding mathematical approximated values for e
7226 (euler number), pi (greek PI), phi (golden ratio)
7229 the input width and height
7232 same as @var{w} / @var{h}
7235 input sample aspect ratio
7238 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
7241 horizontal and vertical chroma subsample values. For example for the
7242 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7245 @subsection Examples
7250 To change the display aspect ratio to 16:9, specify one of the following:
7258 To change the sample aspect ratio to 10:11, specify:
7264 To set a display aspect ratio of 16:9, and specify a maximum integer value of
7265 1000 in the aspect ratio reduction, use the command:
7267 setdar=ratio=16/9:max=1000
7275 Force field for the output video frame.
7277 The @code{setfield} filter marks the interlace type field for the
7278 output frames. It does not change the input frame, but only sets the
7279 corresponding property, which affects how the frame is treated by
7280 following filters (e.g. @code{fieldorder} or @code{yadif}).
7282 The filter accepts the following options:
7287 Available values are:
7291 Keep the same field property.
7294 Mark the frame as bottom-field-first.
7297 Mark the frame as top-field-first.
7300 Mark the frame as progressive.
7306 Show a line containing various information for each input video frame.
7307 The input video is not modified.
7309 The shown line contains a sequence of key/value pairs of the form
7310 @var{key}:@var{value}.
7312 A description of each shown parameter follows:
7316 sequential number of the input frame, starting from 0
7319 Presentation TimeStamp of the input frame, expressed as a number of
7320 time base units. The time base unit depends on the filter input pad.
7323 Presentation TimeStamp of the input frame, expressed as a number of
7327 position of the frame in the input stream, -1 if this information in
7328 unavailable and/or meaningless (for example in case of synthetic video)
7334 sample aspect ratio of the input frame, expressed in the form
7338 size of the input frame. For the syntax of this option, check the "Video size"
7339 section in the ffmpeg-utils manual.
7342 interlaced mode ("P" for "progressive", "T" for top field first, "B"
7343 for bottom field first)
7346 1 if the frame is a key frame, 0 otherwise
7349 picture type of the input frame ("I" for an I-frame, "P" for a
7350 P-frame, "B" for a B-frame, "?" for unknown type).
7351 Check also the documentation of the @code{AVPictureType} enum and of
7352 the @code{av_get_picture_type_char} function defined in
7353 @file{libavutil/avutil.h}.
7356 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
7358 @item plane_checksum
7359 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
7360 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
7366 Blur the input video without impacting the outlines.
7368 The filter accepts the following options:
7371 @item luma_radius, lr
7372 Set the luma radius. The option value must be a float number in
7373 the range [0.1,5.0] that specifies the variance of the gaussian filter
7374 used to blur the image (slower if larger). Default value is 1.0.
7376 @item luma_strength, ls
7377 Set the luma strength. The option value must be a float number
7378 in the range [-1.0,1.0] that configures the blurring. A value included
7379 in [0.0,1.0] will blur the image whereas a value included in
7380 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7382 @item luma_threshold, lt
7383 Set the luma threshold used as a coefficient to determine
7384 whether a pixel should be blurred or not. The option value must be an
7385 integer in the range [-30,30]. A value of 0 will filter all the image,
7386 a value included in [0,30] will filter flat areas and a value included
7387 in [-30,0] will filter edges. Default value is 0.
7389 @item chroma_radius, cr
7390 Set the chroma radius. The option value must be a float number in
7391 the range [0.1,5.0] that specifies the variance of the gaussian filter
7392 used to blur the image (slower if larger). Default value is 1.0.
7394 @item chroma_strength, cs
7395 Set the chroma strength. The option value must be a float number
7396 in the range [-1.0,1.0] that configures the blurring. A value included
7397 in [0.0,1.0] will blur the image whereas a value included in
7398 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7400 @item chroma_threshold, ct
7401 Set the chroma threshold used as a coefficient to determine
7402 whether a pixel should be blurred or not. The option value must be an
7403 integer in the range [-30,30]. A value of 0 will filter all the image,
7404 a value included in [0,30] will filter flat areas and a value included
7405 in [-30,0] will filter edges. Default value is 0.
7408 If a chroma option is not explicitly set, the corresponding luma value
7413 Convert between different stereoscopic image formats.
7415 The filters accept the following options:
7419 Set stereoscopic image format of input.
7421 Available values for input image formats are:
7424 side by side parallel (left eye left, right eye right)
7427 side by side crosseye (right eye left, left eye right)
7430 side by side parallel with half width resolution
7431 (left eye left, right eye right)
7434 side by side crosseye with half width resolution
7435 (right eye left, left eye right)
7438 above-below (left eye above, right eye below)
7441 above-below (right eye above, left eye below)
7444 above-below with half height resolution
7445 (left eye above, right eye below)
7448 above-below with half height resolution
7449 (right eye above, left eye below)
7452 alternating frames (left eye first, right eye second)
7455 alternating frames (right eye first, left eye second)
7457 Default value is @samp{sbsl}.
7461 Set stereoscopic image format of output.
7463 Available values for output image formats are all the input formats as well as:
7466 anaglyph red/blue gray
7467 (red filter on left eye, blue filter on right eye)
7470 anaglyph red/green gray
7471 (red filter on left eye, green filter on right eye)
7474 anaglyph red/cyan gray
7475 (red filter on left eye, cyan filter on right eye)
7478 anaglyph red/cyan half colored
7479 (red filter on left eye, cyan filter on right eye)
7482 anaglyph red/cyan color
7483 (red filter on left eye, cyan filter on right eye)
7486 anaglyph red/cyan color optimized with the least squares projection of dubois
7487 (red filter on left eye, cyan filter on right eye)
7490 anaglyph green/magenta gray
7491 (green filter on left eye, magenta filter on right eye)
7494 anaglyph green/magenta half colored
7495 (green filter on left eye, magenta filter on right eye)
7498 anaglyph green/magenta colored
7499 (green filter on left eye, magenta filter on right eye)
7502 anaglyph green/magenta color optimized with the least squares projection of dubois
7503 (green filter on left eye, magenta filter on right eye)
7506 anaglyph yellow/blue gray
7507 (yellow filter on left eye, blue filter on right eye)
7510 anaglyph yellow/blue half colored
7511 (yellow filter on left eye, blue filter on right eye)
7514 anaglyph yellow/blue colored
7515 (yellow filter on left eye, blue filter on right eye)
7518 anaglyph yellow/blue color optimized with the least squares projection of dubois
7519 (yellow filter on left eye, blue filter on right eye)
7522 interleaved rows (left eye has top row, right eye starts on next row)
7525 interleaved rows (right eye has top row, left eye starts on next row)
7528 mono output (left eye only)
7531 mono output (right eye only)
7534 Default value is @samp{arcd}.
7537 @subsection Examples
7541 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
7547 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
7555 Apply a simple postprocessing filter that compresses and decompresses the image
7556 at several (or - in the case of @option{quality} level @code{6} - all) shifts
7557 and average the results.
7559 The filter accepts the following options:
7563 Set quality. This option defines the number of levels for averaging. It accepts
7564 an integer in the range 0-6. If set to @code{0}, the filter will have no
7565 effect. A value of @code{6} means the higher quality. For each increment of
7566 that value the speed drops by a factor of approximately 2. Default value is
7570 Force a constant quantization parameter. If not set, the filter will use the QP
7571 from the video stream (if available).
7574 Set thresholding mode. Available modes are:
7578 Set hard thresholding (default).
7580 Set soft thresholding (better de-ringing effect, but likely blurrier).
7584 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
7585 option may cause flicker since the B-Frames have often larger QP. Default is
7586 @code{0} (not enabled).
7592 Draw subtitles on top of input video using the libass library.
7594 To enable compilation of this filter you need to configure FFmpeg with
7595 @code{--enable-libass}. This filter also requires a build with libavcodec and
7596 libavformat to convert the passed subtitles file to ASS (Advanced Substation
7597 Alpha) subtitles format.
7599 The filter accepts the following options:
7603 Set the filename of the subtitle file to read. It must be specified.
7606 Specify the size of the original video, the video for which the ASS file
7607 was composed. For the syntax of this option, check the "Video size" section in
7608 the ffmpeg-utils manual. Due to a misdesign in ASS aspect ratio arithmetic,
7609 this is necessary to correctly scale the fonts if the aspect ratio has been
7613 Set subtitles input character encoding. @code{subtitles} filter only. Only
7614 useful if not UTF-8.
7617 If the first key is not specified, it is assumed that the first value
7618 specifies the @option{filename}.
7620 For example, to render the file @file{sub.srt} on top of the input
7621 video, use the command:
7626 which is equivalent to:
7628 subtitles=filename=sub.srt
7633 Scale the input by 2x and smooth using the Super2xSaI (Scale and
7634 Interpolate) pixel art scaling algorithm.
7636 Useful for enlarging pixel art images without reducing sharpness.
7643 Apply telecine process to the video.
7645 This filter accepts the following options:
7654 The default value is @code{top}.
7658 A string of numbers representing the pulldown pattern you wish to apply.
7659 The default value is @code{23}.
7663 Some typical patterns:
7668 24p: 2332 (preferred)
7675 24p: 222222222223 ("Euro pulldown")
7681 Select the most representative frame in a given sequence of consecutive frames.
7683 The filter accepts the following options:
7687 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
7688 will pick one of them, and then handle the next batch of @var{n} frames until
7689 the end. Default is @code{100}.
7692 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
7693 value will result in a higher memory usage, so a high value is not recommended.
7695 @subsection Examples
7699 Extract one picture each 50 frames:
7705 Complete example of a thumbnail creation with @command{ffmpeg}:
7707 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
7713 Tile several successive frames together.
7715 The filter accepts the following options:
7720 Set the grid size (i.e. the number of lines and columns). For the syntax of
7721 this option, check the "Video size" section in the ffmpeg-utils manual.
7724 Set the maximum number of frames to render in the given area. It must be less
7725 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
7726 the area will be used.
7729 Set the outer border margin in pixels.
7732 Set the inner border thickness (i.e. the number of pixels between frames). For
7733 more advanced padding options (such as having different values for the edges),
7734 refer to the pad video filter.
7737 Specify the color of the unused areaFor the syntax of this option, check the
7738 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
7742 @subsection Examples
7746 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
7748 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
7750 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
7751 duplicating each output frame to accomodate the originally detected frame
7755 Display @code{5} pictures in an area of @code{3x2} frames,
7756 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
7757 mixed flat and named options:
7759 tile=3x2:nb_frames=5:padding=7:margin=2
7765 Perform various types of temporal field interlacing.
7767 Frames are counted starting from 1, so the first input frame is
7770 The filter accepts the following options:
7775 Specify the mode of the interlacing. This option can also be specified
7776 as a value alone. See below for a list of values for this option.
7778 Available values are:
7782 Move odd frames into the upper field, even into the lower field,
7783 generating a double height frame at half frame rate.
7786 Only output even frames, odd frames are dropped, generating a frame with
7787 unchanged height at half frame rate.
7790 Only output odd frames, even frames are dropped, generating a frame with
7791 unchanged height at half frame rate.
7794 Expand each frame to full height, but pad alternate lines with black,
7795 generating a frame with double height at the same input frame rate.
7797 @item interleave_top, 4
7798 Interleave the upper field from odd frames with the lower field from
7799 even frames, generating a frame with unchanged height at half frame rate.
7801 @item interleave_bottom, 5
7802 Interleave the lower field from odd frames with the upper field from
7803 even frames, generating a frame with unchanged height at half frame rate.
7805 @item interlacex2, 6
7806 Double frame rate with unchanged height. Frames are inserted each
7807 containing the second temporal field from the previous input frame and
7808 the first temporal field from the next input frame. This mode relies on
7809 the top_field_first flag. Useful for interlaced video displays with no
7810 field synchronisation.
7813 Numeric values are deprecated but are accepted for backward
7814 compatibility reasons.
7816 Default mode is @code{merge}.
7819 Specify flags influencing the filter process.
7821 Available value for @var{flags} is:
7824 @item low_pass_filter, vlfp
7825 Enable vertical low-pass filtering in the filter.
7826 Vertical low-pass filtering is required when creating an interlaced
7827 destination from a progressive source which contains high-frequency
7828 vertical detail. Filtering will reduce interlace 'twitter' and Moire
7831 Vertical low-pass filtering can only be enabled for @option{mode}
7832 @var{interleave_top} and @var{interleave_bottom}.
7839 Transpose rows with columns in the input video and optionally flip it.
7841 This filter accepts the following options:
7846 Specify the transposition direction.
7848 Can assume the following values:
7850 @item 0, 4, cclock_flip
7851 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
7859 Rotate by 90 degrees clockwise, that is:
7867 Rotate by 90 degrees counterclockwise, that is:
7874 @item 3, 7, clock_flip
7875 Rotate by 90 degrees clockwise and vertically flip, that is:
7883 For values between 4-7, the transposition is only done if the input
7884 video geometry is portrait and not landscape. These values are
7885 deprecated, the @code{passthrough} option should be used instead.
7887 Numerical values are deprecated, and should be dropped in favor of
7891 Do not apply the transposition if the input geometry matches the one
7892 specified by the specified value. It accepts the following values:
7895 Always apply transposition.
7897 Preserve portrait geometry (when @var{height} >= @var{width}).
7899 Preserve landscape geometry (when @var{width} >= @var{height}).
7902 Default value is @code{none}.
7905 For example to rotate by 90 degrees clockwise and preserve portrait
7908 transpose=dir=1:passthrough=portrait
7911 The command above can also be specified as:
7913 transpose=1:portrait
7917 Trim the input so that the output contains one continuous subpart of the input.
7919 This filter accepts the following options:
7922 Specify time of the start of the kept section, i.e. the frame with the
7923 timestamp @var{start} will be the first frame in the output.
7926 Specify time of the first frame that will be dropped, i.e. the frame
7927 immediately preceding the one with the timestamp @var{end} will be the last
7928 frame in the output.
7931 Same as @var{start}, except this option sets the start timestamp in timebase
7932 units instead of seconds.
7935 Same as @var{end}, except this option sets the end timestamp in timebase units
7939 Specify maximum duration of the output.
7942 Number of the first frame that should be passed to output.
7945 Number of the first frame that should be dropped.
7948 @option{start}, @option{end}, @option{duration} are expressed as time
7949 duration specifications, check the "Time duration" section in the
7950 ffmpeg-utils manual.
7952 Note that the first two sets of the start/end options and the @option{duration}
7953 option look at the frame timestamp, while the _frame variants simply count the
7954 frames that pass through the filter. Also note that this filter does not modify
7955 the timestamps. If you wish that the output timestamps start at zero, insert a
7956 setpts filter after the trim filter.
7958 If multiple start or end options are set, this filter tries to be greedy and
7959 keep all the frames that match at least one of the specified constraints. To keep
7960 only the part that matches all the constraints at once, chain multiple trim
7963 The defaults are such that all the input is kept. So it is possible to set e.g.
7964 just the end values to keep everything before the specified time.
7969 drop everything except the second minute of input
7971 ffmpeg -i INPUT -vf trim=60:120
7975 keep only the first second
7977 ffmpeg -i INPUT -vf trim=duration=1
7985 Sharpen or blur the input video.
7987 It accepts the following parameters:
7990 @item luma_msize_x, lx
7991 Set the luma matrix horizontal size. It must be an odd integer between
7992 3 and 63, default value is 5.
7994 @item luma_msize_y, ly
7995 Set the luma matrix vertical size. It must be an odd integer between 3
7996 and 63, default value is 5.
7998 @item luma_amount, la
7999 Set the luma effect strength. It can be a float number, reasonable
8000 values lay between -1.5 and 1.5.
8002 Negative values will blur the input video, while positive values will
8003 sharpen it, a value of zero will disable the effect.
8005 Default value is 1.0.
8007 @item chroma_msize_x, cx
8008 Set the chroma matrix horizontal size. It must be an odd integer
8009 between 3 and 63, default value is 5.
8011 @item chroma_msize_y, cy
8012 Set the chroma matrix vertical size. It must be an odd integer
8013 between 3 and 63, default value is 5.
8015 @item chroma_amount, ca
8016 Set the chroma effect strength. It can be a float number, reasonable
8017 values lay between -1.5 and 1.5.
8019 Negative values will blur the input video, while positive values will
8020 sharpen it, a value of zero will disable the effect.
8022 Default value is 0.0.
8025 If set to 1, specify using OpenCL capabilities, only available if
8026 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
8030 All parameters are optional and default to the equivalent of the
8031 string '5:5:1.0:5:5:0.0'.
8033 @subsection Examples
8037 Apply strong luma sharpen effect:
8039 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
8043 Apply strong blur of both luma and chroma parameters:
8045 unsharp=7:7:-2:7:7:-2
8049 @anchor{vidstabdetect}
8050 @section vidstabdetect
8052 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
8053 @ref{vidstabtransform} for pass 2.
8055 This filter generates a file with relative translation and rotation
8056 transform information about subsequent frames, which is then used by
8057 the @ref{vidstabtransform} filter.
8059 To enable compilation of this filter you need to configure FFmpeg with
8060 @code{--enable-libvidstab}.
8062 This filter accepts the following options:
8066 Set the path to the file used to write the transforms information.
8067 Default value is @file{transforms.trf}.
8070 Set how shaky the video is and how quick the camera is. It accepts an
8071 integer in the range 1-10, a value of 1 means little shakiness, a
8072 value of 10 means strong shakiness. Default value is 5.
8075 Set the accuracy of the detection process. It must be a value in the
8076 range 1-15. A value of 1 means low accuracy, a value of 15 means high
8077 accuracy. Default value is 15.
8080 Set stepsize of the search process. The region around minimum is
8081 scanned with 1 pixel resolution. Default value is 6.
8084 Set minimum contrast. Below this value a local measurement field is
8085 discarded. Must be a floating point value in the range 0-1. Default
8089 Set reference frame number for tripod mode.
8091 If enabled, the motion of the frames is compared to a reference frame
8092 in the filtered stream, identified by the specified number. The idea
8093 is to compensate all movements in a more-or-less static scene and keep
8094 the camera view absolutely still.
8096 If set to 0, it is disabled. The frames are counted starting from 1.
8099 Show fields and transforms in the resulting frames. It accepts an
8100 integer in the range 0-2. Default value is 0, which disables any
8104 @subsection Examples
8114 Analyze strongly shaky movie and put the results in file
8115 @file{mytransforms.trf}:
8117 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
8121 Visualize the result of internal transformations in the resulting
8124 vidstabdetect=show=1
8128 Analyze a video with medium shakiness using @command{ffmpeg}:
8130 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
8134 @anchor{vidstabtransform}
8135 @section vidstabtransform
8137 Video stabilization/deshaking: pass 2 of 2,
8138 see @ref{vidstabdetect} for pass 1.
8140 Read a file with transform information for each frame and
8141 apply/compensate them. Together with the @ref{vidstabdetect}
8142 filter this can be used to deshake videos. See also
8143 @url{http://public.hronopik.de/vid.stab}. It is important to also use
8144 the unsharp filter, see below.
8146 To enable compilation of this filter you need to configure FFmpeg with
8147 @code{--enable-libvidstab}.
8153 Set path to the file used to read the transforms. Default value is
8154 @file{transforms.trf}).
8157 Set the number of frames (value*2 + 1) used for lowpass filtering the
8158 camera movements. Default value is 10.
8160 For example a number of 10 means that 21 frames are used (10 in the
8161 past and 10 in the future) to smoothen the motion in the video. A
8162 larger values leads to a smoother video, but limits the acceleration
8163 of the camera (pan/tilt movements). 0 is a special case where a
8164 static camera is simulated.
8167 Set the camera path optimization algorithm.
8169 Accepted values are:
8172 gaussian kernel low-pass filter on camera motion (default)
8174 averaging on transformations
8178 Set maximal number of pixels to translate frames. Default value is -1,
8182 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
8183 value is -1, meaning no limit.
8186 Specify how to deal with borders that may be visible due to movement
8189 Available values are:
8192 keep image information from previous frame (default)
8194 fill the border black
8198 Invert transforms if set to 1. Default value is 0.
8201 Consider transforms as relative to previsou frame if set to 1,
8202 absolute if set to 0. Default value is 0.
8205 Set percentage to zoom. A positive value will result in a zoom-in
8206 effect, a negative value in a zoom-out effect. Default value is 0 (no
8210 Set optimal zooming to avoid borders.
8212 Accepted values are:
8217 optimal static zoom value is determined (only very strong movements
8218 will lead to visible borders) (default)
8220 optimal adaptive zoom value is determined (no borders will be
8221 visible), see @option{zoomspeed}
8224 Note that the value given at zoom is added to the one calculated here.
8227 Set percent to zoom maximally each frame (enabled when
8228 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
8232 Specify type of interpolation.
8234 Available values are:
8239 linear only horizontal
8241 linear in both directions (default)
8243 cubic in both directions (slow)
8247 Enable virtual tripod mode if set to 1, which is equivalent to
8248 @code{relative=0:smoothing=0}. Default value is 0.
8250 Use also @code{tripod} option of @ref{vidstabdetect}.
8253 Increase log verbosity if set to 1. Also the detected global motions
8254 are written to the temporary file @file{global_motions.trf}. Default
8258 @subsection Examples
8262 Use @command{ffmpeg} for a typical stabilization with default values:
8264 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
8267 Note the use of the unsharp filter which is always recommended.
8270 Zoom in a bit more and load transform data from a given file:
8272 vidstabtransform=zoom=5:input="mytransforms.trf"
8276 Smoothen the video even more:
8278 vidstabtransform=smoothing=30
8284 Flip the input video vertically.
8286 For example, to vertically flip a video with @command{ffmpeg}:
8288 ffmpeg -i in.avi -vf "vflip" out.avi
8293 Make or reverse a natural vignetting effect.
8295 The filter accepts the following options:
8299 Set lens angle expression as a number of radians.
8301 The value is clipped in the @code{[0,PI/2]} range.
8303 Default value: @code{"PI/5"}
8307 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
8311 Set forward/backward mode.
8313 Available modes are:
8316 The larger the distance from the central point, the darker the image becomes.
8319 The larger the distance from the central point, the brighter the image becomes.
8320 This can be used to reverse a vignette effect, though there is no automatic
8321 detection to extract the lens @option{angle} and other settings (yet). It can
8322 also be used to create a burning effect.
8325 Default value is @samp{forward}.
8328 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
8330 It accepts the following values:
8333 Evaluate expressions only once during the filter initialization.
8336 Evaluate expressions for each incoming frame. This is way slower than the
8337 @samp{init} mode since it requires all the scalers to be re-computed, but it
8338 allows advanced dynamic expressions.
8341 Default value is @samp{init}.
8344 Set dithering to reduce the circular banding effects. Default is @code{1}
8348 Set vignette aspect. This setting allows to adjust the shape of the vignette.
8349 Setting this value to the SAR of the input will make a rectangular vignetting
8350 following the dimensions of the video.
8352 Default is @code{1/1}.
8355 @subsection Expressions
8357 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
8358 following parameters.
8363 input width and height
8366 the number of input frame, starting from 0
8369 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
8370 @var{TB} units, NAN if undefined
8373 frame rate of the input video, NAN if the input frame rate is unknown
8376 the PTS (Presentation TimeStamp) of the filtered video frame,
8377 expressed in seconds, NAN if undefined
8380 time base of the input video
8384 @subsection Examples
8388 Apply simple strong vignetting effect:
8394 Make a flickering vignetting:
8396 vignette='PI/4+random(1)*PI/50':eval=frame
8403 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
8404 Deinterlacing Filter").
8406 Based on the process described by Martin Weston for BBC R&D, and
8407 implemented based on the de-interlace algorithm written by Jim
8408 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
8409 uses filter coefficients calculated by BBC R&D.
8411 There are two sets of filter coefficients, so called "simple":
8412 and "complex". Which set of filter coefficients is used can
8413 be set by passing an optional parameter:
8417 Set the interlacing filter coefficients. Accepts one of the following values:
8421 Simple filter coefficient set.
8423 More-complex filter coefficient set.
8425 Default value is @samp{complex}.
8428 Specify which frames to deinterlace. Accept one of the following values:
8432 Deinterlace all frames,
8434 Only deinterlace frames marked as interlaced.
8437 Default value is @samp{all}.
8443 Deinterlace the input video ("yadif" means "yet another deinterlacing
8446 This filter accepts the following options:
8452 The interlacing mode to adopt, accepts one of the following values:
8456 output 1 frame for each frame
8458 output 1 frame for each field
8459 @item 2, send_frame_nospatial
8460 like @code{send_frame} but skip spatial interlacing check
8461 @item 3, send_field_nospatial
8462 like @code{send_field} but skip spatial interlacing check
8465 Default value is @code{send_frame}.
8468 The picture field parity assumed for the input interlaced video, accepts one of
8469 the following values:
8473 assume top field first
8475 assume bottom field first
8477 enable automatic detection
8480 Default value is @code{auto}.
8481 If interlacing is unknown or decoder does not export this information,
8482 top field first will be assumed.
8485 Specify which frames to deinterlace. Accept one of the following
8490 deinterlace all frames
8492 only deinterlace frames marked as interlaced
8495 Default value is @code{all}.
8498 @c man end VIDEO FILTERS
8500 @chapter Video Sources
8501 @c man begin VIDEO SOURCES
8503 Below is a description of the currently available video sources.
8507 Buffer video frames, and make them available to the filter chain.
8509 This source is mainly intended for a programmatic use, in particular
8510 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
8512 This source accepts the following options:
8517 Specify the size (width and height) of the buffered video frames. For the
8518 syntax of this option, check the "Video size" section in the ffmpeg-utils
8528 A string representing the pixel format of the buffered video frames.
8529 It may be a number corresponding to a pixel format, or a pixel format
8533 Specify the timebase assumed by the timestamps of the buffered frames.
8536 Specify the frame rate expected for the video stream.
8538 @item pixel_aspect, sar
8539 Specify the sample aspect ratio assumed by the video frames.
8542 Specify the optional parameters to be used for the scale filter which
8543 is automatically inserted when an input change is detected in the
8544 input size or format.
8549 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
8552 will instruct the source to accept video frames with size 320x240 and
8553 with format "yuv410p", assuming 1/24 as the timestamps timebase and
8554 square pixels (1:1 sample aspect ratio).
8555 Since the pixel format with name "yuv410p" corresponds to the number 6
8556 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
8557 this example corresponds to:
8559 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
8562 Alternatively, the options can be specified as a flat string, but this
8563 syntax is deprecated:
8565 @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}]
8569 Create a pattern generated by an elementary cellular automaton.
8571 The initial state of the cellular automaton can be defined through the
8572 @option{filename}, and @option{pattern} options. If such options are
8573 not specified an initial state is created randomly.
8575 At each new frame a new row in the video is filled with the result of
8576 the cellular automaton next generation. The behavior when the whole
8577 frame is filled is defined by the @option{scroll} option.
8579 This source accepts the following options:
8583 Read the initial cellular automaton state, i.e. the starting row, from
8585 In the file, each non-whitespace character is considered an alive
8586 cell, a newline will terminate the row, and further characters in the
8587 file will be ignored.
8590 Read the initial cellular automaton state, i.e. the starting row, from
8591 the specified string.
8593 Each non-whitespace character in the string is considered an alive
8594 cell, a newline will terminate the row, and further characters in the
8595 string will be ignored.
8598 Set the video rate, that is the number of frames generated per second.
8601 @item random_fill_ratio, ratio
8602 Set the random fill ratio for the initial cellular automaton row. It
8603 is a floating point number value ranging from 0 to 1, defaults to
8606 This option is ignored when a file or a pattern is specified.
8608 @item random_seed, seed
8609 Set the seed for filling randomly the initial row, must be an integer
8610 included between 0 and UINT32_MAX. If not specified, or if explicitly
8611 set to -1, the filter will try to use a good random seed on a best
8615 Set the cellular automaton rule, it is a number ranging from 0 to 255.
8616 Default value is 110.
8619 Set the size of the output video. For the syntax of this option, check
8620 the "Video size" section in the ffmpeg-utils manual.
8622 If @option{filename} or @option{pattern} is specified, the size is set
8623 by default to the width of the specified initial state row, and the
8624 height is set to @var{width} * PHI.
8626 If @option{size} is set, it must contain the width of the specified
8627 pattern string, and the specified pattern will be centered in the
8630 If a filename or a pattern string is not specified, the size value
8631 defaults to "320x518" (used for a randomly generated initial state).
8634 If set to 1, scroll the output upward when all the rows in the output
8635 have been already filled. If set to 0, the new generated row will be
8636 written over the top row just after the bottom row is filled.
8639 @item start_full, full
8640 If set to 1, completely fill the output with generated rows before
8641 outputting the first frame.
8642 This is the default behavior, for disabling set the value to 0.
8645 If set to 1, stitch the left and right row edges together.
8646 This is the default behavior, for disabling set the value to 0.
8649 @subsection Examples
8653 Read the initial state from @file{pattern}, and specify an output of
8656 cellauto=f=pattern:s=200x400
8660 Generate a random initial row with a width of 200 cells, with a fill
8663 cellauto=ratio=2/3:s=200x200
8667 Create a pattern generated by rule 18 starting by a single alive cell
8668 centered on an initial row with width 100:
8670 cellauto=p=@@:s=100x400:full=0:rule=18
8674 Specify a more elaborated initial pattern:
8676 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
8683 Generate a Mandelbrot set fractal, and progressively zoom towards the
8684 point specified with @var{start_x} and @var{start_y}.
8686 This source accepts the following options:
8691 Set the terminal pts value. Default value is 400.
8694 Set the terminal scale value.
8695 Must be a floating point value. Default value is 0.3.
8698 Set the inner coloring mode, that is the algorithm used to draw the
8699 Mandelbrot fractal internal region.
8701 It shall assume one of the following values:
8706 Show time until convergence.
8708 Set color based on point closest to the origin of the iterations.
8713 Default value is @var{mincol}.
8716 Set the bailout value. Default value is 10.0.
8719 Set the maximum of iterations performed by the rendering
8720 algorithm. Default value is 7189.
8723 Set outer coloring mode.
8724 It shall assume one of following values:
8726 @item iteration_count
8727 Set iteration cound mode.
8728 @item normalized_iteration_count
8729 set normalized iteration count mode.
8731 Default value is @var{normalized_iteration_count}.
8734 Set frame rate, expressed as number of frames per second. Default
8738 Set frame size. For the syntax of this option, check the "Video
8739 size" section in the ffmpeg-utils manual. Default value is "640x480".
8742 Set the initial scale value. Default value is 3.0.
8745 Set the initial x position. Must be a floating point value between
8746 -100 and 100. Default value is -0.743643887037158704752191506114774.
8749 Set the initial y position. Must be a floating point value between
8750 -100 and 100. Default value is -0.131825904205311970493132056385139.
8755 Generate various test patterns, as generated by the MPlayer test filter.
8757 The size of the generated video is fixed, and is 256x256.
8758 This source is useful in particular for testing encoding features.
8760 This source accepts the following options:
8765 Specify the frame rate of the sourced video, as the number of frames
8766 generated per second. It has to be a string in the format
8767 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
8768 number or a valid video frame rate abbreviation. The default value is
8772 Set the video duration of the sourced video. The accepted syntax is:
8777 See also the function @code{av_parse_time()}.
8779 If not specified, or the expressed duration is negative, the video is
8780 supposed to be generated forever.
8784 Set the number or the name of the test to perform. Supported tests are:
8799 Default value is "all", which will cycle through the list of all tests.
8802 For example the following:
8807 will generate a "dc_luma" test pattern.
8811 Provide a frei0r source.
8813 To enable compilation of this filter you need to install the frei0r
8814 header and configure FFmpeg with @code{--enable-frei0r}.
8816 This source accepts the following options:
8821 The size of the video to generate. For the syntax of this option, check the
8822 "Video size" section in the ffmpeg-utils manual.
8825 Framerate of the generated video, may be a string of the form
8826 @var{num}/@var{den} or a frame rate abbreviation.
8829 The name to the frei0r source to load. For more information regarding frei0r and
8830 how to set the parameters read the section @ref{frei0r} in the description of
8834 A '|'-separated list of parameters to pass to the frei0r source.
8838 For example, to generate a frei0r partik0l source with size 200x200
8839 and frame rate 10 which is overlayed on the overlay filter main input:
8841 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
8846 Generate a life pattern.
8848 This source is based on a generalization of John Conway's life game.
8850 The sourced input represents a life grid, each pixel represents a cell
8851 which can be in one of two possible states, alive or dead. Every cell
8852 interacts with its eight neighbours, which are the cells that are
8853 horizontally, vertically, or diagonally adjacent.
8855 At each interaction the grid evolves according to the adopted rule,
8856 which specifies the number of neighbor alive cells which will make a
8857 cell stay alive or born. The @option{rule} option allows to specify
8860 This source accepts the following options:
8864 Set the file from which to read the initial grid state. In the file,
8865 each non-whitespace character is considered an alive cell, and newline
8866 is used to delimit the end of each row.
8868 If this option is not specified, the initial grid is generated
8872 Set the video rate, that is the number of frames generated per second.
8875 @item random_fill_ratio, ratio
8876 Set the random fill ratio for the initial random grid. It is a
8877 floating point number value ranging from 0 to 1, defaults to 1/PHI.
8878 It is ignored when a file is specified.
8880 @item random_seed, seed
8881 Set the seed for filling the initial random grid, must be an integer
8882 included between 0 and UINT32_MAX. If not specified, or if explicitly
8883 set to -1, the filter will try to use a good random seed on a best
8889 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
8890 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
8891 @var{NS} specifies the number of alive neighbor cells which make a
8892 live cell stay alive, and @var{NB} the number of alive neighbor cells
8893 which make a dead cell to become alive (i.e. to "born").
8894 "s" and "b" can be used in place of "S" and "B", respectively.
8896 Alternatively a rule can be specified by an 18-bits integer. The 9
8897 high order bits are used to encode the next cell state if it is alive
8898 for each number of neighbor alive cells, the low order bits specify
8899 the rule for "borning" new cells. Higher order bits encode for an
8900 higher number of neighbor cells.
8901 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
8902 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
8904 Default value is "S23/B3", which is the original Conway's game of life
8905 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
8906 cells, and will born a new cell if there are three alive cells around
8910 Set the size of the output video. For the syntax of this option, check the
8911 "Video size" section in the ffmpeg-utils manual.
8913 If @option{filename} is specified, the size is set by default to the
8914 same size of the input file. If @option{size} is set, it must contain
8915 the size specified in the input file, and the initial grid defined in
8916 that file is centered in the larger resulting area.
8918 If a filename is not specified, the size value defaults to "320x240"
8919 (used for a randomly generated initial grid).
8922 If set to 1, stitch the left and right grid edges together, and the
8923 top and bottom edges also. Defaults to 1.
8926 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
8927 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
8928 value from 0 to 255.
8931 Set the color of living (or new born) cells.
8934 Set the color of dead cells. If @option{mold} is set, this is the first color
8935 used to represent a dead cell.
8938 Set mold color, for definitely dead and moldy cells.
8940 For the syntax of these 3 color options, check the "Color" section in the
8941 ffmpeg-utils manual.
8944 @subsection Examples
8948 Read a grid from @file{pattern}, and center it on a grid of size
8951 life=f=pattern:s=300x300
8955 Generate a random grid of size 200x200, with a fill ratio of 2/3:
8957 life=ratio=2/3:s=200x200
8961 Specify a custom rule for evolving a randomly generated grid:
8967 Full example with slow death effect (mold) using @command{ffplay}:
8969 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
8974 @anchor{haldclutsrc}
8978 @anchor{smptehdbars}
8980 @section color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
8982 The @code{color} source provides an uniformly colored input.
8984 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
8985 @ref{haldclut} filter.
8987 The @code{nullsrc} source returns unprocessed video frames. It is
8988 mainly useful to be employed in analysis / debugging tools, or as the
8989 source for filters which ignore the input data.
8991 The @code{rgbtestsrc} source generates an RGB test pattern useful for
8992 detecting RGB vs BGR issues. You should see a red, green and blue
8993 stripe from top to bottom.
8995 The @code{smptebars} source generates a color bars pattern, based on
8996 the SMPTE Engineering Guideline EG 1-1990.
8998 The @code{smptehdbars} source generates a color bars pattern, based on
8999 the SMPTE RP 219-2002.
9001 The @code{testsrc} source generates a test video pattern, showing a
9002 color pattern, a scrolling gradient and a timestamp. This is mainly
9003 intended for testing purposes.
9005 The sources accept the following options:
9010 Specify the color of the source, only available in the @code{color}
9011 source. For the syntax of this option, check the "Color" section in the
9012 ffmpeg-utils manual.
9015 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
9016 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
9017 pixels to be used as identity matrix for 3D lookup tables. Each component is
9018 coded on a @code{1/(N*N)} scale.
9021 Specify the size of the sourced video. For the syntax of this option, check the
9022 "Video size" section in the ffmpeg-utils manual. The default value is
9025 This option is not available with the @code{haldclutsrc} filter.
9028 Specify the frame rate of the sourced video, as the number of frames
9029 generated per second. It has to be a string in the format
9030 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
9031 number or a valid video frame rate abbreviation. The default value is
9035 Set the sample aspect ratio of the sourced video.
9038 Set the video duration of the sourced video. The accepted syntax is:
9040 [-]HH[:MM[:SS[.m...]]]
9043 See also the function @code{av_parse_time()}.
9045 If not specified, or the expressed duration is negative, the video is
9046 supposed to be generated forever.
9049 Set the number of decimals to show in the timestamp, only available in the
9050 @code{testsrc} source.
9052 The displayed timestamp value will correspond to the original
9053 timestamp value multiplied by the power of 10 of the specified
9054 value. Default value is 0.
9057 For example the following:
9059 testsrc=duration=5.3:size=qcif:rate=10
9062 will generate a video with a duration of 5.3 seconds, with size
9063 176x144 and a frame rate of 10 frames per second.
9065 The following graph description will generate a red source
9066 with an opacity of 0.2, with size "qcif" and a frame rate of 10
9069 color=c=red@@0.2:s=qcif:r=10
9072 If the input content is to be ignored, @code{nullsrc} can be used. The
9073 following command generates noise in the luminance plane by employing
9074 the @code{geq} filter:
9076 nullsrc=s=256x256, geq=random(1)*255:128:128
9079 @subsection Commands
9081 The @code{color} source supports the following commands:
9085 Set the color of the created image. Accepts the same syntax of the
9086 corresponding @option{color} option.
9089 @c man end VIDEO SOURCES
9091 @chapter Video Sinks
9092 @c man begin VIDEO SINKS
9094 Below is a description of the currently available video sinks.
9098 Buffer video frames, and make them available to the end of the filter
9101 This sink is mainly intended for a programmatic use, in particular
9102 through the interface defined in @file{libavfilter/buffersink.h}
9103 or the options system.
9105 It accepts a pointer to an AVBufferSinkContext structure, which
9106 defines the incoming buffers' formats, to be passed as the opaque
9107 parameter to @code{avfilter_init_filter} for initialization.
9111 Null video sink, do absolutely nothing with the input video. It is
9112 mainly useful as a template and to be employed in analysis / debugging
9115 @c man end VIDEO SINKS
9117 @chapter Multimedia Filters
9118 @c man begin MULTIMEDIA FILTERS
9120 Below is a description of the currently available multimedia filters.
9122 @section avectorscope
9124 Convert input audio to a video output, representing the audio vector
9127 The filter is used to measure the difference between channels of stereo
9128 audio stream. A monoaural signal, consisting of identical left and right
9129 signal, results in straight vertical line. Any stereo separation is visible
9130 as a deviation from this line, creating a Lissajous figure.
9131 If the straight (or deviation from it) but horizontal line appears this
9132 indicates that the left and right channels are out of phase.
9134 The filter accepts the following options:
9138 Set the vectorscope mode.
9140 Available values are:
9143 Lissajous rotated by 45 degrees.
9146 Same as above but not rotated.
9149 Default value is @samp{lissajous}.
9152 Set the video size for the output. For the syntax of this option, check the "Video size"
9153 section in the ffmpeg-utils manual. Default value is @code{400x400}.
9156 Set the output frame rate. Default value is @code{25}.
9161 Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}.
9162 Allowed range is @code{[0, 255]}.
9167 Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}.
9168 Allowed range is @code{[0, 255]}.
9171 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
9174 @subsection Examples
9178 Complete example using @command{ffplay}:
9180 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
9181 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
9187 Concatenate audio and video streams, joining them together one after the
9190 The filter works on segments of synchronized video and audio streams. All
9191 segments must have the same number of streams of each type, and that will
9192 also be the number of streams at output.
9194 The filter accepts the following options:
9199 Set the number of segments. Default is 2.
9202 Set the number of output video streams, that is also the number of video
9203 streams in each segment. Default is 1.
9206 Set the number of output audio streams, that is also the number of video
9207 streams in each segment. Default is 0.
9210 Activate unsafe mode: do not fail if segments have a different format.
9214 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
9215 @var{a} audio outputs.
9217 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
9218 segment, in the same order as the outputs, then the inputs for the second
9221 Related streams do not always have exactly the same duration, for various
9222 reasons including codec frame size or sloppy authoring. For that reason,
9223 related synchronized streams (e.g. a video and its audio track) should be
9224 concatenated at once. The concat filter will use the duration of the longest
9225 stream in each segment (except the last one), and if necessary pad shorter
9226 audio streams with silence.
9228 For this filter to work correctly, all segments must start at timestamp 0.
9230 All corresponding streams must have the same parameters in all segments; the
9231 filtering system will automatically select a common pixel format for video
9232 streams, and a common sample format, sample rate and channel layout for
9233 audio streams, but other settings, such as resolution, must be converted
9234 explicitly by the user.
9236 Different frame rates are acceptable but will result in variable frame rate
9237 at output; be sure to configure the output file to handle it.
9239 @subsection Examples
9243 Concatenate an opening, an episode and an ending, all in bilingual version
9244 (video in stream 0, audio in streams 1 and 2):
9246 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
9247 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
9248 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
9249 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
9253 Concatenate two parts, handling audio and video separately, using the
9254 (a)movie sources, and adjusting the resolution:
9256 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
9257 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
9258 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
9260 Note that a desync will happen at the stitch if the audio and video streams
9261 do not have exactly the same duration in the first file.
9267 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
9268 it unchanged. By default, it logs a message at a frequency of 10Hz with the
9269 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
9270 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
9272 The filter also has a video output (see the @var{video} option) with a real
9273 time graph to observe the loudness evolution. The graphic contains the logged
9274 message mentioned above, so it is not printed anymore when this option is set,
9275 unless the verbose logging is set. The main graphing area contains the
9276 short-term loudness (3 seconds of analysis), and the gauge on the right is for
9277 the momentary loudness (400 milliseconds).
9279 More information about the Loudness Recommendation EBU R128 on
9280 @url{http://tech.ebu.ch/loudness}.
9282 The filter accepts the following options:
9287 Activate the video output. The audio stream is passed unchanged whether this
9288 option is set or no. The video stream will be the first output stream if
9289 activated. Default is @code{0}.
9292 Set the video size. This option is for video only. For the syntax of this
9293 option, check the "Video size" section in the ffmpeg-utils manual. Default
9294 and minimum resolution is @code{640x480}.
9297 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
9298 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
9299 other integer value between this range is allowed.
9302 Set metadata injection. If set to @code{1}, the audio input will be segmented
9303 into 100ms output frames, each of them containing various loudness information
9304 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
9306 Default is @code{0}.
9309 Force the frame logging level.
9311 Available values are:
9314 information logging level
9316 verbose logging level
9319 By default, the logging level is set to @var{info}. If the @option{video} or
9320 the @option{metadata} options are set, it switches to @var{verbose}.
9323 @subsection Examples
9327 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
9329 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
9333 Run an analysis with @command{ffmpeg}:
9335 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
9339 @section interleave, ainterleave
9341 Temporally interleave frames from several inputs.
9343 @code{interleave} works with video inputs, @code{ainterleave} with audio.
9345 These filters read frames from several inputs and send the oldest
9346 queued frame to the output.
9348 Input streams must have a well defined, monotonically increasing frame
9351 In order to submit one frame to output, these filters need to enqueue
9352 at least one frame for each input, so they cannot work in case one
9353 input is not yet terminated and will not receive incoming frames.
9355 For example consider the case when one input is a @code{select} filter
9356 which always drop input frames. The @code{interleave} filter will keep
9357 reading from that input, but it will never be able to send new frames
9358 to output until the input will send an end-of-stream signal.
9360 Also, depending on inputs synchronization, the filters will drop
9361 frames in case one input receives more frames than the other ones, and
9362 the queue is already filled.
9364 These filters accept the following options:
9368 Set the number of different inputs, it is 2 by default.
9371 @subsection Examples
9375 Interleave frames belonging to different streams using @command{ffmpeg}:
9377 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
9381 Add flickering blur effect:
9383 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
9387 @section perms, aperms
9389 Set read/write permissions for the output frames.
9391 These filters are mainly aimed at developers to test direct path in the
9392 following filter in the filtergraph.
9394 The filters accept the following options:
9398 Select the permissions mode.
9400 It accepts the following values:
9403 Do nothing. This is the default.
9405 Set all the output frames read-only.
9407 Set all the output frames directly writable.
9409 Make the frame read-only if writable, and writable if read-only.
9411 Set each output frame read-only or writable randomly.
9415 Set the seed for the @var{random} mode, must be an integer included between
9416 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9417 @code{-1}, the filter will try to use a good random seed on a best effort
9421 Note: in case of auto-inserted filter between the permission filter and the
9422 following one, the permission might not be received as expected in that
9423 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
9424 perms/aperms filter can avoid this problem.
9426 @section select, aselect
9428 Select frames to pass in output.
9430 This filter accepts the following options:
9435 Set expression, which is evaluated for each input frame.
9437 If the expression is evaluated to zero, the frame is discarded.
9439 If the evaluation result is negative or NaN, the frame is sent to the
9440 first output; otherwise it is sent to the output with index
9441 @code{ceil(val)-1}, assuming that the input index starts from 0.
9443 For example a value of @code{1.2} corresponds to the output with index
9444 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
9447 Set the number of outputs. The output to which to send the selected
9448 frame is based on the result of the evaluation. Default value is 1.
9451 The expression can contain the following constants:
9455 the sequential number of the filtered frame, starting from 0
9458 the sequential number of the selected frame, starting from 0
9460 @item prev_selected_n
9461 the sequential number of the last selected frame, NAN if undefined
9464 timebase of the input timestamps
9467 the PTS (Presentation TimeStamp) of the filtered video frame,
9468 expressed in @var{TB} units, NAN if undefined
9471 the PTS (Presentation TimeStamp) of the filtered video frame,
9472 expressed in seconds, NAN if undefined
9475 the PTS of the previously filtered video frame, NAN if undefined
9477 @item prev_selected_pts
9478 the PTS of the last previously filtered video frame, NAN if undefined
9480 @item prev_selected_t
9481 the PTS of the last previously selected video frame, NAN if undefined
9484 the PTS of the first video frame in the video, NAN if undefined
9487 the time of the first video frame in the video, NAN if undefined
9489 @item pict_type @emph{(video only)}
9490 the type of the filtered frame, can assume one of the following
9502 @item interlace_type @emph{(video only)}
9503 the frame interlace type, can assume one of the following values:
9506 the frame is progressive (not interlaced)
9508 the frame is top-field-first
9510 the frame is bottom-field-first
9513 @item consumed_sample_n @emph{(audio only)}
9514 the number of selected samples before the current frame
9516 @item samples_n @emph{(audio only)}
9517 the number of samples in the current frame
9519 @item sample_rate @emph{(audio only)}
9520 the input sample rate
9523 1 if the filtered frame is a key-frame, 0 otherwise
9526 the position in the file of the filtered frame, -1 if the information
9527 is not available (e.g. for synthetic video)
9529 @item scene @emph{(video only)}
9530 value between 0 and 1 to indicate a new scene; a low value reflects a low
9531 probability for the current frame to introduce a new scene, while a higher
9532 value means the current frame is more likely to be one (see the example below)
9536 The default value of the select expression is "1".
9538 @subsection Examples
9542 Select all frames in input:
9547 The example above is the same as:
9559 Select only I-frames:
9561 select='eq(pict_type\,I)'
9565 Select one frame every 100:
9567 select='not(mod(n\,100))'
9571 Select only frames contained in the 10-20 time interval:
9573 select=between(t\,10\,20)
9577 Select only I frames contained in the 10-20 time interval:
9579 select=between(t\,10\,20)*eq(pict_type\,I)
9583 Select frames with a minimum distance of 10 seconds:
9585 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
9589 Use aselect to select only audio frames with samples number > 100:
9591 aselect='gt(samples_n\,100)'
9595 Create a mosaic of the first scenes:
9597 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
9600 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
9604 Send even and odd frames to separate outputs, and compose them:
9606 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
9610 @section sendcmd, asendcmd
9612 Send commands to filters in the filtergraph.
9614 These filters read commands to be sent to other filters in the
9617 @code{sendcmd} must be inserted between two video filters,
9618 @code{asendcmd} must be inserted between two audio filters, but apart
9619 from that they act the same way.
9621 The specification of commands can be provided in the filter arguments
9622 with the @var{commands} option, or in a file specified by the
9623 @var{filename} option.
9625 These filters accept the following options:
9628 Set the commands to be read and sent to the other filters.
9630 Set the filename of the commands to be read and sent to the other
9634 @subsection Commands syntax
9636 A commands description consists of a sequence of interval
9637 specifications, comprising a list of commands to be executed when a
9638 particular event related to that interval occurs. The occurring event
9639 is typically the current frame time entering or leaving a given time
9642 An interval is specified by the following syntax:
9644 @var{START}[-@var{END}] @var{COMMANDS};
9647 The time interval is specified by the @var{START} and @var{END} times.
9648 @var{END} is optional and defaults to the maximum time.
9650 The current frame time is considered within the specified interval if
9651 it is included in the interval [@var{START}, @var{END}), that is when
9652 the time is greater or equal to @var{START} and is lesser than
9655 @var{COMMANDS} consists of a sequence of one or more command
9656 specifications, separated by ",", relating to that interval. The
9657 syntax of a command specification is given by:
9659 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
9662 @var{FLAGS} is optional and specifies the type of events relating to
9663 the time interval which enable sending the specified command, and must
9664 be a non-null sequence of identifier flags separated by "+" or "|" and
9665 enclosed between "[" and "]".
9667 The following flags are recognized:
9670 The command is sent when the current frame timestamp enters the
9671 specified interval. In other words, the command is sent when the
9672 previous frame timestamp was not in the given interval, and the
9676 The command is sent when the current frame timestamp leaves the
9677 specified interval. In other words, the command is sent when the
9678 previous frame timestamp was in the given interval, and the
9682 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
9685 @var{TARGET} specifies the target of the command, usually the name of
9686 the filter class or a specific filter instance name.
9688 @var{COMMAND} specifies the name of the command for the target filter.
9690 @var{ARG} is optional and specifies the optional list of argument for
9691 the given @var{COMMAND}.
9693 Between one interval specification and another, whitespaces, or
9694 sequences of characters starting with @code{#} until the end of line,
9695 are ignored and can be used to annotate comments.
9697 A simplified BNF description of the commands specification syntax
9700 @var{COMMAND_FLAG} ::= "enter" | "leave"
9701 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
9702 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
9703 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
9704 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
9705 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
9708 @subsection Examples
9712 Specify audio tempo change at second 4:
9714 asendcmd=c='4.0 atempo tempo 1.5',atempo
9718 Specify a list of drawtext and hue commands in a file.
9720 # show text in the interval 5-10
9721 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
9722 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
9724 # desaturate the image in the interval 15-20
9725 15.0-20.0 [enter] hue s 0,
9726 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
9728 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
9730 # apply an exponential saturation fade-out effect, starting from time 25
9731 25 [enter] hue s exp(25-t)
9734 A filtergraph allowing to read and process the above command list
9735 stored in a file @file{test.cmd}, can be specified with:
9737 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
9742 @section setpts, asetpts
9744 Change the PTS (presentation timestamp) of the input frames.
9746 @code{setpts} works on video frames, @code{asetpts} on audio frames.
9748 This filter accepts the following options:
9753 The expression which is evaluated for each frame to construct its timestamp.
9757 The expression is evaluated through the eval API and can contain the following
9762 frame rate, only defined for constant frame-rate video
9765 the presentation timestamp in input
9768 the count of the input frame for video or the number of consumed samples,
9769 not including the current frame for audio, starting from 0.
9771 @item NB_CONSUMED_SAMPLES
9772 the number of consumed samples, not including the current frame (only
9776 the number of samples in the current frame (only audio)
9778 @item SAMPLE_RATE, SR
9782 the PTS of the first frame
9785 the time in seconds of the first frame
9788 tell if the current frame is interlaced
9791 the time in seconds of the current frame
9794 original position in the file of the frame, or undefined if undefined
9795 for the current frame
9801 previous input time in seconds
9807 previous output time in seconds
9810 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
9814 wallclock (RTC) time at the start of the movie in microseconds
9817 timebase of the input timestamps
9821 @subsection Examples
9825 Start counting PTS from zero
9831 Apply fast motion effect:
9837 Apply slow motion effect:
9843 Set fixed rate of 25 frames per second:
9849 Set fixed rate 25 fps with some jitter:
9851 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
9855 Apply an offset of 10 seconds to the input PTS:
9861 Generate timestamps from a "live source" and rebase onto the current timebase:
9863 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
9867 Generate timestamps by counting samples:
9874 @section settb, asettb
9876 Set the timebase to use for the output frames timestamps.
9877 It is mainly useful for testing timebase configuration.
9879 This filter accepts the following options:
9884 The expression which is evaluated into the output timebase.
9888 The value for @option{tb} is an arithmetic expression representing a
9889 rational. The expression can contain the constants "AVTB" (the default
9890 timebase), "intb" (the input timebase) and "sr" (the sample rate,
9891 audio only). Default value is "intb".
9893 @subsection Examples
9897 Set the timebase to 1/25:
9903 Set the timebase to 1/10:
9909 Set the timebase to 1001/1000:
9915 Set the timebase to 2*intb:
9921 Set the default timebase value:
9927 @section showspectrum
9929 Convert input audio to a video output, representing the audio frequency
9932 The filter accepts the following options:
9936 Specify the video size for the output. For the syntax of this option, check
9937 the "Video size" section in the ffmpeg-utils manual. Default value is
9941 Specify if the spectrum should slide along the window. Default value is
9945 Specify display mode.
9947 It accepts the following values:
9950 all channels are displayed in the same row
9952 all channels are displayed in separate rows
9955 Default value is @samp{combined}.
9958 Specify display color mode.
9960 It accepts the following values:
9963 each channel is displayed in a separate color
9965 each channel is is displayed using the same color scheme
9968 Default value is @samp{channel}.
9971 Specify scale used for calculating intensity color values.
9973 It accepts the following values:
9978 square root, default
9985 Default value is @samp{sqrt}.
9988 Set saturation modifier for displayed colors. Negative values provide
9989 alternative color scheme. @code{0} is no saturation at all.
9990 Saturation must be in [-10.0, 10.0] range.
9991 Default value is @code{1}.
9994 Set window function.
9996 It accepts the following values:
9999 No samples pre-processing (do not expect this to be faster)
10008 Default value is @code{hann}.
10011 The usage is very similar to the showwaves filter; see the examples in that
10014 @subsection Examples
10018 Large window with logarithmic color scaling:
10020 showspectrum=s=1280x480:scale=log
10024 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
10026 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
10027 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
10033 Convert input audio to a video output, representing the samples waves.
10035 The filter accepts the following options:
10039 Specify the video size for the output. For the syntax of this option, check
10040 the "Video size" section in the ffmpeg-utils manual. Default value
10046 Available values are:
10049 Draw a point for each sample.
10052 Draw a vertical line for each sample.
10055 Default value is @code{point}.
10058 Set the number of samples which are printed on the same column. A
10059 larger value will decrease the frame rate. Must be a positive
10060 integer. This option can be set only if the value for @var{rate}
10061 is not explicitly specified.
10064 Set the (approximate) output frame rate. This is done by setting the
10065 option @var{n}. Default value is "25".
10069 @subsection Examples
10073 Output the input file audio and the corresponding video representation
10076 amovie=a.mp3,asplit[out0],showwaves[out1]
10080 Create a synthetic signal and show it with showwaves, forcing a
10081 frame rate of 30 frames per second:
10083 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
10087 @section split, asplit
10089 Split input into several identical outputs.
10091 @code{asplit} works with audio input, @code{split} with video.
10093 The filter accepts a single parameter which specifies the number of outputs. If
10094 unspecified, it defaults to 2.
10096 @subsection Examples
10100 Create two separate outputs from the same input:
10102 [in] split [out0][out1]
10106 To create 3 or more outputs, you need to specify the number of
10109 [in] asplit=3 [out0][out1][out2]
10113 Create two separate outputs from the same input, one cropped and
10116 [in] split [splitout1][splitout2];
10117 [splitout1] crop=100:100:0:0 [cropout];
10118 [splitout2] pad=200:200:100:100 [padout];
10122 Create 5 copies of the input audio with @command{ffmpeg}:
10124 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
10130 Receive commands sent through a libzmq client, and forward them to
10131 filters in the filtergraph.
10133 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
10134 must be inserted between two video filters, @code{azmq} between two
10137 To enable these filters you need to install the libzmq library and
10138 headers and configure FFmpeg with @code{--enable-libzmq}.
10140 For more information about libzmq see:
10141 @url{http://www.zeromq.org/}
10143 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
10144 receives messages sent through a network interface defined by the
10145 @option{bind_address} option.
10147 The received message must be in the form:
10149 @var{TARGET} @var{COMMAND} [@var{ARG}]
10152 @var{TARGET} specifies the target of the command, usually the name of
10153 the filter class or a specific filter instance name.
10155 @var{COMMAND} specifies the name of the command for the target filter.
10157 @var{ARG} is optional and specifies the optional argument list for the
10158 given @var{COMMAND}.
10160 Upon reception, the message is processed and the corresponding command
10161 is injected into the filtergraph. Depending on the result, the filter
10162 will send a reply to the client, adopting the format:
10164 @var{ERROR_CODE} @var{ERROR_REASON}
10168 @var{MESSAGE} is optional.
10170 @subsection Examples
10172 Look at @file{tools/zmqsend} for an example of a zmq client which can
10173 be used to send commands processed by these filters.
10175 Consider the following filtergraph generated by @command{ffplay}
10177 ffplay -dumpgraph 1 -f lavfi "
10178 color=s=100x100:c=red [l];
10179 color=s=100x100:c=blue [r];
10180 nullsrc=s=200x100, zmq [bg];
10181 [bg][l] overlay [bg+l];
10182 [bg+l][r] overlay=x=100 "
10185 To change the color of the left side of the video, the following
10186 command can be used:
10188 echo Parsed_color_0 c yellow | tools/zmqsend
10191 To change the right side:
10193 echo Parsed_color_1 c pink | tools/zmqsend
10196 @c man end MULTIMEDIA FILTERS
10198 @chapter Multimedia Sources
10199 @c man begin MULTIMEDIA SOURCES
10201 Below is a description of the currently available multimedia sources.
10205 This is the same as @ref{movie} source, except it selects an audio
10211 Read audio and/or video stream(s) from a movie container.
10213 This filter accepts the following options:
10217 The name of the resource to read (not necessarily a file but also a device or a
10218 stream accessed through some protocol).
10220 @item format_name, f
10221 Specifies the format assumed for the movie to read, and can be either
10222 the name of a container or an input device. If not specified the
10223 format is guessed from @var{movie_name} or by probing.
10225 @item seek_point, sp
10226 Specifies the seek point in seconds, the frames will be output
10227 starting from this seek point, the parameter is evaluated with
10228 @code{av_strtod} so the numerical value may be suffixed by an IS
10229 postfix. Default value is "0".
10232 Specifies the streams to read. Several streams can be specified,
10233 separated by "+". The source will then have as many outputs, in the
10234 same order. The syntax is explained in the ``Stream specifiers''
10235 section in the ffmpeg manual. Two special names, "dv" and "da" specify
10236 respectively the default (best suited) video and audio stream. Default
10237 is "dv", or "da" if the filter is called as "amovie".
10239 @item stream_index, si
10240 Specifies the index of the video stream to read. If the value is -1,
10241 the best suited video stream will be automatically selected. Default
10242 value is "-1". Deprecated. If the filter is called "amovie", it will select
10243 audio instead of video.
10246 Specifies how many times to read the stream in sequence.
10247 If the value is less than 1, the stream will be read again and again.
10248 Default value is "1".
10250 Note that when the movie is looped the source timestamps are not
10251 changed, so it will generate non monotonically increasing timestamps.
10254 This filter allows to overlay a second video on top of main input of
10255 a filtergraph as shown in this graph:
10257 input -----------> deltapts0 --> overlay --> output
10260 movie --> scale--> deltapts1 -------+
10263 @subsection Examples
10267 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
10268 on top of the input labelled as "in":
10270 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
10271 [in] setpts=PTS-STARTPTS [main];
10272 [main][over] overlay=16:16 [out]
10276 Read from a video4linux2 device, and overlay it on top of the input
10279 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
10280 [in] setpts=PTS-STARTPTS [main];
10281 [main][over] overlay=16:16 [out]
10285 Read the first video stream and the audio stream with id 0x81 from
10286 dvd.vob; the video is connected to the pad named "video" and the audio is
10287 connected to the pad named "audio":
10289 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
10293 @c man end MULTIMEDIA SOURCES