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 Select how the @var{text} is expanded. Can be either @code{none},
3553 @code{strftime} (deprecated) or
3554 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
3558 If true, check and fix text coords to avoid clipping.
3561 The color to be used for drawing fonts. For the syntax of this option, check
3562 the "Color" section in the ffmpeg-utils manual.
3564 The default value of @var{fontcolor} is "black".
3567 The font file to be used for drawing text. Path must be included.
3568 This parameter is mandatory.
3571 The font size to be used for drawing text.
3572 The default value of @var{fontsize} is 16.
3575 Flags to be used for loading the fonts.
3577 The flags map the corresponding flags supported by libfreetype, and are
3578 a combination of the following values:
3585 @item vertical_layout
3586 @item force_autohint
3589 @item ignore_global_advance_width
3591 @item ignore_transform
3597 Default value is "render".
3599 For more information consult the documentation for the FT_LOAD_*
3603 The color to be used for drawing a shadow behind the drawn text. For the
3604 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
3606 The default value of @var{shadowcolor} is "black".
3610 The x and y offsets for the text shadow position with respect to the
3611 position of the text. They can be either positive or negative
3612 values. Default value for both is "0".
3615 The starting frame number for the n/frame_num variable. The default value
3619 The size in number of spaces to use for rendering the tab.
3623 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
3624 format. It can be used with or without text parameter. @var{timecode_rate}
3625 option must be specified.
3627 @item timecode_rate, rate, r
3628 Set the timecode frame rate (timecode only).
3631 The text string to be drawn. The text must be a sequence of UTF-8
3633 This parameter is mandatory if no file is specified with the parameter
3637 A text file containing text to be drawn. The text must be a sequence
3638 of UTF-8 encoded characters.
3640 This parameter is mandatory if no text string is specified with the
3641 parameter @var{text}.
3643 If both @var{text} and @var{textfile} are specified, an error is thrown.
3646 If set to 1, the @var{textfile} will be reloaded before each frame.
3647 Be sure to update it atomically, or it may be read partially, or even fail.
3651 The expressions which specify the offsets where text will be drawn
3652 within the video frame. They are relative to the top/left border of the
3655 The default value of @var{x} and @var{y} is "0".
3657 See below for the list of accepted constants and functions.
3660 The parameters for @var{x} and @var{y} are expressions containing the
3661 following constants and functions:
3665 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
3669 horizontal and vertical chroma subsample values. For example for the
3670 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3673 the height of each text line
3681 @item max_glyph_a, ascent
3682 the maximum distance from the baseline to the highest/upper grid
3683 coordinate used to place a glyph outline point, for all the rendered
3685 It is a positive value, due to the grid's orientation with the Y axis
3688 @item max_glyph_d, descent
3689 the maximum distance from the baseline to the lowest grid coordinate
3690 used to place a glyph outline point, for all the rendered glyphs.
3691 This is a negative value, due to the grid's orientation, with the Y axis
3695 maximum glyph height, that is the maximum height for all the glyphs
3696 contained in the rendered text, it is equivalent to @var{ascent} -
3700 maximum glyph width, that is the maximum width for all the glyphs
3701 contained in the rendered text
3704 the number of input frame, starting from 0
3706 @item rand(min, max)
3707 return a random number included between @var{min} and @var{max}
3710 input sample aspect ratio
3713 timestamp expressed in seconds, NAN if the input timestamp is unknown
3716 the height of the rendered text
3719 the width of the rendered text
3723 the x and y offset coordinates where the text is drawn.
3725 These parameters allow the @var{x} and @var{y} expressions to refer
3726 each other, so you can for example specify @code{y=x/dar}.
3729 If libavfilter was built with @code{--enable-fontconfig}, then
3730 @option{fontfile} can be a fontconfig pattern or omitted.
3732 @anchor{drawtext_expansion}
3733 @subsection Text expansion
3735 If @option{expansion} is set to @code{strftime},
3736 the filter recognizes strftime() sequences in the provided text and
3737 expands them accordingly. Check the documentation of strftime(). This
3738 feature is deprecated.
3740 If @option{expansion} is set to @code{none}, the text is printed verbatim.
3742 If @option{expansion} is set to @code{normal} (which is the default),
3743 the following expansion mechanism is used.
3745 The backslash character '\', followed by any character, always expands to
3746 the second character.
3748 Sequence of the form @code{%@{...@}} are expanded. The text between the
3749 braces is a function name, possibly followed by arguments separated by ':'.
3750 If the arguments contain special characters or delimiters (':' or '@}'),
3751 they should be escaped.
3753 Note that they probably must also be escaped as the value for the
3754 @option{text} option in the filter argument string and as the filter
3755 argument in the filtergraph description, and possibly also for the shell,
3756 that makes up to four levels of escaping; using a text file avoids these
3759 The following functions are available:
3764 The expression evaluation result.
3766 It must take one argument specifying the expression to be evaluated,
3767 which accepts the same constants and functions as the @var{x} and
3768 @var{y} values. Note that not all constants should be used, for
3769 example the text size is not known when evaluating the expression, so
3770 the constants @var{text_w} and @var{text_h} will have an undefined
3774 The time at which the filter is running, expressed in UTC.
3775 It can accept an argument: a strftime() format string.
3778 The time at which the filter is running, expressed in the local time zone.
3779 It can accept an argument: a strftime() format string.
3782 Frame metadata. It must take one argument specifying metadata key.
3785 The frame number, starting from 0.
3788 A 1 character description of the current picture type.
3791 The timestamp of the current frame, in seconds, with microsecond accuracy.
3795 @subsection Examples
3799 Draw "Test Text" with font FreeSerif, using the default values for the
3800 optional parameters.
3803 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
3807 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
3808 and y=50 (counting from the top-left corner of the screen), text is
3809 yellow with a red box around it. Both the text and the box have an
3813 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
3814 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
3817 Note that the double quotes are not necessary if spaces are not used
3818 within the parameter list.
3821 Show the text at the center of the video frame:
3823 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
3827 Show a text line sliding from right to left in the last row of the video
3828 frame. The file @file{LONG_LINE} is assumed to contain a single line
3831 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3835 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3837 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3841 Draw a single green letter "g", at the center of the input video.
3842 The glyph baseline is placed at half screen height.
3844 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3848 Show text for 1 second every 3 seconds:
3850 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
3854 Use fontconfig to set the font. Note that the colons need to be escaped.
3856 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3860 Print the date of a real-time encoding (see strftime(3)):
3862 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3867 For more information about libfreetype, check:
3868 @url{http://www.freetype.org/}.
3870 For more information about fontconfig, check:
3871 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3875 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3877 The filter accepts the following options:
3882 Set low and high threshold values used by the Canny thresholding
3885 The high threshold selects the "strong" edge pixels, which are then
3886 connected through 8-connectivity with the "weak" edge pixels selected
3887 by the low threshold.
3889 @var{low} and @var{high} threshold values must be choosen in the range
3890 [0,1], and @var{low} should be lesser or equal to @var{high}.
3892 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3898 edgedetect=low=0.1:high=0.4
3901 @section extractplanes
3903 Extract color channel components from input video stream into
3904 separate grayscale video streams.
3906 The filter accepts the following option:
3910 Set plane(s) to extract.
3912 Available values for planes are:
3923 Choosing planes not available in the input will result in an error.
3924 That means you cannot select @code{r}, @code{g}, @code{b} planes
3925 with @code{y}, @code{u}, @code{v} planes at same time.
3928 @subsection Examples
3932 Extract luma, u and v color channel component from input video frame
3933 into 3 grayscale outputs:
3935 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
3941 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
3943 For each input image, the filter will compute the optimal mapping from
3944 the input to the output given the codebook length, that is the number
3945 of distinct output colors.
3947 This filter accepts the following options.
3950 @item codebook_length, l
3951 Set codebook length. The value must be a positive integer, and
3952 represents the number of distinct output colors. Default value is 256.
3955 Set the maximum number of iterations to apply for computing the optimal
3956 mapping. The higher the value the better the result and the higher the
3957 computation time. Default value is 1.
3960 Set a random seed, must be an integer included between 0 and
3961 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
3962 will try to use a good random seed on a best effort basis.
3967 Apply fade-in/out effect to input video.
3969 This filter accepts the following options:
3973 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3975 Default is @code{in}.
3977 @item start_frame, s
3978 Specify the number of the start frame for starting to apply the fade
3979 effect. Default is 0.
3982 The number of frames for which the fade effect has to last. At the end of the
3983 fade-in effect the output video will have the same intensity as the input video,
3984 at the end of the fade-out transition the output video will be filled with the
3985 selected @option{color}.
3989 If set to 1, fade only alpha channel, if one exists on the input.
3992 @item start_time, st
3993 Specify the timestamp (in seconds) of the frame to start to apply the fade
3994 effect. If both start_frame and start_time are specified, the fade will start at
3995 whichever comes last. Default is 0.
3998 The number of seconds for which the fade effect has to last. At the end of the
3999 fade-in effect the output video will have the same intensity as the input video,
4000 at the end of the fade-out transition the output video will be filled with the
4001 selected @option{color}.
4002 If both duration and nb_frames are specified, duration is used. Default is 0.
4005 Specify the color of the fade. Default is "black".
4008 @subsection Examples
4012 Fade in first 30 frames of video:
4017 The command above is equivalent to:
4023 Fade out last 45 frames of a 200-frame video:
4026 fade=type=out:start_frame=155:nb_frames=45
4030 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
4032 fade=in:0:25, fade=out:975:25
4036 Make first 5 frames yellow, then fade in from frame 5-24:
4038 fade=in:5:20:color=yellow
4042 Fade in alpha over first 25 frames of video:
4044 fade=in:0:25:alpha=1
4048 Make first 5.5 seconds black, then fade in for 0.5 seconds:
4050 fade=t=in:st=5.5:d=0.5
4057 Extract a single field from an interlaced image using stride
4058 arithmetic to avoid wasting CPU time. The output frames are marked as
4061 The filter accepts the following options:
4065 Specify whether to extract the top (if the value is @code{0} or
4066 @code{top}) or the bottom field (if the value is @code{1} or
4072 Field matching filter for inverse telecine. It is meant to reconstruct the
4073 progressive frames from a telecined stream. The filter does not drop duplicated
4074 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
4075 followed by a decimation filter such as @ref{decimate} in the filtergraph.
4077 The separation of the field matching and the decimation is notably motivated by
4078 the possibility of inserting a de-interlacing filter fallback between the two.
4079 If the source has mixed telecined and real interlaced content,
4080 @code{fieldmatch} will not be able to match fields for the interlaced parts.
4081 But these remaining combed frames will be marked as interlaced, and thus can be
4082 de-interlaced by a later filter such as @ref{yadif} before decimation.
4084 In addition to the various configuration options, @code{fieldmatch} can take an
4085 optional second stream, activated through the @option{ppsrc} option. If
4086 enabled, the frames reconstruction will be based on the fields and frames from
4087 this second stream. This allows the first input to be pre-processed in order to
4088 help the various algorithms of the filter, while keeping the output lossless
4089 (assuming the fields are matched properly). Typically, a field-aware denoiser,
4090 or brightness/contrast adjustments can help.
4092 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
4093 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
4094 which @code{fieldmatch} is based on. While the semantic and usage are very
4095 close, some behaviour and options names can differ.
4097 The filter accepts the following options:
4101 Specify the assumed field order of the input stream. Available values are:
4105 Auto detect parity (use FFmpeg's internal parity value).
4107 Assume bottom field first.
4109 Assume top field first.
4112 Note that it is sometimes recommended not to trust the parity announced by the
4115 Default value is @var{auto}.
4118 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
4119 sense that it won't risk creating jerkiness due to duplicate frames when
4120 possible, but if there are bad edits or blended fields it will end up
4121 outputting combed frames when a good match might actually exist. On the other
4122 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
4123 but will almost always find a good frame if there is one. The other values are
4124 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
4125 jerkiness and creating duplicate frames versus finding good matches in sections
4126 with bad edits, orphaned fields, blended fields, etc.
4128 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
4130 Available values are:
4134 2-way matching (p/c)
4136 2-way matching, and trying 3rd match if still combed (p/c + n)
4138 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
4140 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
4141 still combed (p/c + n + u/b)
4143 3-way matching (p/c/n)
4145 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
4146 detected as combed (p/c/n + u/b)
4149 The parenthesis at the end indicate the matches that would be used for that
4150 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
4153 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
4156 Default value is @var{pc_n}.
4159 Mark the main input stream as a pre-processed input, and enable the secondary
4160 input stream as the clean source to pick the fields from. See the filter
4161 introduction for more details. It is similar to the @option{clip2} feature from
4164 Default value is @code{0} (disabled).
4167 Set the field to match from. It is recommended to set this to the same value as
4168 @option{order} unless you experience matching failures with that setting. In
4169 certain circumstances changing the field that is used to match from can have a
4170 large impact on matching performance. Available values are:
4174 Automatic (same value as @option{order}).
4176 Match from the bottom field.
4178 Match from the top field.
4181 Default value is @var{auto}.
4184 Set whether or not chroma is included during the match comparisons. In most
4185 cases it is recommended to leave this enabled. You should set this to @code{0}
4186 only if your clip has bad chroma problems such as heavy rainbowing or other
4187 artifacts. Setting this to @code{0} could also be used to speed things up at
4188 the cost of some accuracy.
4190 Default value is @code{1}.
4194 These define an exclusion band which excludes the lines between @option{y0} and
4195 @option{y1} from being included in the field matching decision. An exclusion
4196 band can be used to ignore subtitles, a logo, or other things that may
4197 interfere with the matching. @option{y0} sets the starting scan line and
4198 @option{y1} sets the ending line; all lines in between @option{y0} and
4199 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
4200 @option{y0} and @option{y1} to the same value will disable the feature.
4201 @option{y0} and @option{y1} defaults to @code{0}.
4204 Set the scene change detection threshold as a percentage of maximum change on
4205 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
4206 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
4207 @option{scthresh} is @code{[0.0, 100.0]}.
4209 Default value is @code{12.0}.
4212 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
4213 account the combed scores of matches when deciding what match to use as the
4214 final match. Available values are:
4218 No final matching based on combed scores.
4220 Combed scores are only used when a scene change is detected.
4222 Use combed scores all the time.
4225 Default is @var{sc}.
4228 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
4229 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
4230 Available values are:
4234 No forced calculation.
4236 Force p/c/n calculations.
4238 Force p/c/n/u/b calculations.
4241 Default value is @var{none}.
4244 This is the area combing threshold used for combed frame detection. This
4245 essentially controls how "strong" or "visible" combing must be to be detected.
4246 Larger values mean combing must be more visible and smaller values mean combing
4247 can be less visible or strong and still be detected. Valid settings are from
4248 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
4249 be detected as combed). This is basically a pixel difference value. A good
4250 range is @code{[8, 12]}.
4252 Default value is @code{9}.
4255 Sets whether or not chroma is considered in the combed frame decision. Only
4256 disable this if your source has chroma problems (rainbowing, etc.) that are
4257 causing problems for the combed frame detection with chroma enabled. Actually,
4258 using @option{chroma}=@var{0} is usually more reliable, except for the case
4259 where there is chroma only combing in the source.
4261 Default value is @code{0}.
4265 Respectively set the x-axis and y-axis size of the window used during combed
4266 frame detection. This has to do with the size of the area in which
4267 @option{combpel} pixels are required to be detected as combed for a frame to be
4268 declared combed. See the @option{combpel} parameter description for more info.
4269 Possible values are any number that is a power of 2 starting at 4 and going up
4272 Default value is @code{16}.
4275 The number of combed pixels inside any of the @option{blocky} by
4276 @option{blockx} size blocks on the frame for the frame to be detected as
4277 combed. While @option{cthresh} controls how "visible" the combing must be, this
4278 setting controls "how much" combing there must be in any localized area (a
4279 window defined by the @option{blockx} and @option{blocky} settings) on the
4280 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
4281 which point no frames will ever be detected as combed). This setting is known
4282 as @option{MI} in TFM/VFM vocabulary.
4284 Default value is @code{80}.
4287 @anchor{p/c/n/u/b meaning}
4288 @subsection p/c/n/u/b meaning
4290 @subsubsection p/c/n
4292 We assume the following telecined stream:
4295 Top fields: 1 2 2 3 4
4296 Bottom fields: 1 2 3 4 4
4299 The numbers correspond to the progressive frame the fields relate to. Here, the
4300 first two frames are progressive, the 3rd and 4th are combed, and so on.
4302 When @code{fieldmatch} is configured to run a matching from bottom
4303 (@option{field}=@var{bottom}) this is how this input stream get transformed:
4308 B 1 2 3 4 4 <-- matching reference
4317 As a result of the field matching, we can see that some frames get duplicated.
4318 To perform a complete inverse telecine, you need to rely on a decimation filter
4319 after this operation. See for instance the @ref{decimate} filter.
4321 The same operation now matching from top fields (@option{field}=@var{top})
4326 T 1 2 2 3 4 <-- matching reference
4336 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
4337 basically, they refer to the frame and field of the opposite parity:
4340 @item @var{p} matches the field of the opposite parity in the previous frame
4341 @item @var{c} matches the field of the opposite parity in the current frame
4342 @item @var{n} matches the field of the opposite parity in the next frame
4347 The @var{u} and @var{b} matching are a bit special in the sense that they match
4348 from the opposite parity flag. In the following examples, we assume that we are
4349 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
4350 'x' is placed above and below each matched fields.
4352 With bottom matching (@option{field}=@var{bottom}):
4357 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4358 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4366 With top matching (@option{field}=@var{top}):
4371 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4372 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4380 @subsection Examples
4382 Simple IVTC of a top field first telecined stream:
4384 fieldmatch=order=tff:combmatch=none, decimate
4387 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
4389 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
4394 Transform the field order of the input video.
4396 This filter accepts the following options:
4401 Output field order. Valid values are @var{tff} for top field first or @var{bff}
4402 for bottom field first.
4405 Default value is @samp{tff}.
4407 Transformation is achieved by shifting the picture content up or down
4408 by one line, and filling the remaining line with appropriate picture content.
4409 This method is consistent with most broadcast field order converters.
4411 If the input video is not flagged as being interlaced, or it is already
4412 flagged as being of the required output field order then this filter does
4413 not alter the incoming video.
4415 This filter is very useful when converting to or from PAL DV material,
4416 which is bottom field first.
4420 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
4425 Buffer input images and send them when they are requested.
4427 This filter is mainly useful when auto-inserted by the libavfilter
4430 The filter does not take parameters.
4435 Convert the input video to one of the specified pixel formats.
4436 Libavfilter will try to pick one that is supported for the input to
4439 This filter accepts the following parameters:
4443 A '|'-separated list of pixel format names, for example
4444 "pix_fmts=yuv420p|monow|rgb24".
4448 @subsection Examples
4452 Convert the input video to the format @var{yuv420p}
4454 format=pix_fmts=yuv420p
4457 Convert the input video to any of the formats in the list
4459 format=pix_fmts=yuv420p|yuv444p|yuv410p
4466 Convert the video to specified constant frame rate by duplicating or dropping
4467 frames as necessary.
4469 This filter accepts the following named parameters:
4473 Desired output frame rate. The default is @code{25}.
4478 Possible values are:
4481 zero round towards 0
4485 round towards -infinity
4487 round towards +infinity
4491 The default is @code{near}.
4494 Assume the first PTS should be the given value, in seconds. This allows for
4495 padding/trimming at the start of stream. By default, no assumption is made
4496 about the first frame's expected PTS, so no padding or trimming is done.
4497 For example, this could be set to 0 to pad the beginning with duplicates of
4498 the first frame if a video stream starts after the audio stream or to trim any
4499 frames with a negative PTS.
4503 Alternatively, the options can be specified as a flat string:
4504 @var{fps}[:@var{round}].
4506 See also the @ref{setpts} filter.
4508 @subsection Examples
4512 A typical usage in order to set the fps to 25:
4518 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
4520 fps=fps=film:round=near
4526 Pack two different video streams into a stereoscopic video, setting proper
4527 metadata on supported codecs. The two views should have the same size and
4528 framerate and processing will stop when the shorter video ends. Please note
4529 that you may conveniently adjust view properties with the @ref{scale} and
4532 This filter accepts the following named parameters:
4536 Desired packing format. Supported values are:
4541 Views are next to each other (default).
4544 Views are on top of each other.
4547 Views are packed by line.
4550 Views are eacked by column.
4553 Views are temporally interleaved.
4559 Some examples follow:
4562 # Convert left and right views into a frame sequential video.
4563 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
4565 # Convert views into a side-by-side video with the same output resolution as the input.
4566 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
4571 Select one frame every N-th frame.
4573 This filter accepts the following option:
4576 Select frame after every @code{step} frames.
4577 Allowed values are positive integers higher than 0. Default value is @code{1}.
4583 Apply a frei0r effect to the input video.
4585 To enable compilation of this filter you need to install the frei0r
4586 header and configure FFmpeg with @code{--enable-frei0r}.
4588 This filter accepts the following options:
4593 The name to the frei0r effect to load. If the environment variable
4594 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
4595 directories specified by the colon separated list in @env{FREIOR_PATH},
4596 otherwise in the standard frei0r paths, which are in this order:
4597 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
4598 @file{/usr/lib/frei0r-1/}.
4601 A '|'-separated list of parameters to pass to the frei0r effect.
4605 A frei0r effect parameter can be a boolean (whose values are specified
4606 with "y" and "n"), a double, a color (specified by the syntax
4607 @var{R}/@var{G}/@var{B}, (@var{R}, @var{G}, and @var{B} being float
4608 numbers from 0.0 to 1.0) or by a color description specified in the "Color"
4609 section in the ffmpeg-utils manual), a position (specified by the syntax @var{X}/@var{Y},
4610 @var{X} and @var{Y} being float numbers) and a string.
4612 The number and kind of parameters depend on the loaded effect. If an
4613 effect parameter is not specified the default value is set.
4615 @subsection Examples
4619 Apply the distort0r effect, set the first two double parameters:
4621 frei0r=filter_name=distort0r:filter_params=0.5|0.01
4625 Apply the colordistance effect, take a color as first parameter:
4627 frei0r=colordistance:0.2/0.3/0.4
4628 frei0r=colordistance:violet
4629 frei0r=colordistance:0x112233
4633 Apply the perspective effect, specify the top left and top right image
4636 frei0r=perspective:0.2/0.2|0.8/0.2
4640 For more information see:
4641 @url{http://frei0r.dyne.org}
4645 The filter accepts the following options:
4649 Set the luminance expression.
4651 Set the chrominance blue expression.
4653 Set the chrominance red expression.
4655 Set the alpha expression.
4657 Set the red expression.
4659 Set the green expression.
4661 Set the blue expression.
4664 The colorspace is selected according to the specified options. If one
4665 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
4666 options is specified, the filter will automatically select a YCbCr
4667 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
4668 @option{blue_expr} options is specified, it will select an RGB
4671 If one of the chrominance expression is not defined, it falls back on the other
4672 one. If no alpha expression is specified it will evaluate to opaque value.
4673 If none of chrominance expressions are specified, they will evaluate
4674 to the luminance expression.
4676 The expressions can use the following variables and functions:
4680 The sequential number of the filtered frame, starting from @code{0}.
4684 The coordinates of the current sample.
4688 The width and height of the image.
4692 Width and height scale depending on the currently filtered plane. It is the
4693 ratio between the corresponding luma plane number of pixels and the current
4694 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4695 @code{0.5,0.5} for chroma planes.
4698 Time of the current frame, expressed in seconds.
4701 Return the value of the pixel at location (@var{x},@var{y}) of the current
4705 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
4709 Return the value of the pixel at location (@var{x},@var{y}) of the
4710 blue-difference chroma plane. Return 0 if there is no such plane.
4713 Return the value of the pixel at location (@var{x},@var{y}) of the
4714 red-difference chroma plane. Return 0 if there is no such plane.
4719 Return the value of the pixel at location (@var{x},@var{y}) of the
4720 red/green/blue component. Return 0 if there is no such component.
4723 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
4724 plane. Return 0 if there is no such plane.
4727 For functions, if @var{x} and @var{y} are outside the area, the value will be
4728 automatically clipped to the closer edge.
4730 @subsection Examples
4734 Flip the image horizontally:
4740 Generate a bidimensional sine wave, with angle @code{PI/3} and a
4741 wavelength of 100 pixels:
4743 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
4747 Generate a fancy enigmatic moving light:
4749 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
4753 Generate a quick emboss effect:
4755 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
4759 Modify RGB components depending on pixel position:
4761 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
4767 Fix the banding artifacts that are sometimes introduced into nearly flat
4768 regions by truncation to 8bit color depth.
4769 Interpolate the gradients that should go where the bands are, and
4772 This filter is designed for playback only. Do not use it prior to
4773 lossy compression, because compression tends to lose the dither and
4774 bring back the bands.
4776 This filter accepts the following options:
4781 The maximum amount by which the filter will change any one pixel. Also the
4782 threshold for detecting nearly flat regions. Acceptable values range from .51 to
4783 64, default value is 1.2, out-of-range values will be clipped to the valid
4787 The neighborhood to fit the gradient to. A larger radius makes for smoother
4788 gradients, but also prevents the filter from modifying the pixels near detailed
4789 regions. Acceptable values are 8-32, default value is 16, out-of-range values
4790 will be clipped to the valid range.
4794 Alternatively, the options can be specified as a flat string:
4795 @var{strength}[:@var{radius}]
4797 @subsection Examples
4801 Apply the filter with a @code{3.5} strength and radius of @code{8}:
4807 Specify radius, omitting the strength (which will fall-back to the default
4818 Apply a Hald CLUT to a video stream.
4820 First input is the video stream to process, and second one is the Hald CLUT.
4821 The Hald CLUT input can be a simple picture or a complete video stream.
4823 The filter accepts the following options:
4827 Force termination when the shortest input terminates. Default is @code{0}.
4829 Continue applying the last CLUT after the end of the stream. A value of
4830 @code{0} disable the filter after the last frame of the CLUT is reached.
4831 Default is @code{1}.
4834 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
4835 filters share the same internals).
4837 More information about the Hald CLUT can be found on Eskil Steenberg's website
4838 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
4840 @subsection Workflow examples
4842 @subsubsection Hald CLUT video stream
4844 Generate an identity Hald CLUT stream altered with various effects:
4846 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
4849 Note: make sure you use a lossless codec.
4851 Then use it with @code{haldclut} to apply it on some random stream:
4853 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
4856 The Hald CLUT will be applied to the 10 first seconds (duration of
4857 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
4858 to the remaining frames of the @code{mandelbrot} stream.
4860 @subsubsection Hald CLUT with preview
4862 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
4863 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
4864 biggest possible square starting at the top left of the picture. The remaining
4865 padding pixels (bottom or right) will be ignored. This area can be used to add
4866 a preview of the Hald CLUT.
4868 Typically, the following generated Hald CLUT will be supported by the
4869 @code{haldclut} filter:
4872 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
4873 pad=iw+320 [padded_clut];
4874 smptebars=s=320x256, split [a][b];
4875 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
4876 [main][b] overlay=W-320" -frames:v 1 clut.png
4879 It contains the original and a preview of the effect of the CLUT: SMPTE color
4880 bars are displayed on the right-top, and below the same color bars processed by
4883 Then, the effect of this Hald CLUT can be visualized with:
4885 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
4890 Flip the input video horizontally.
4892 For example to horizontally flip the input video with @command{ffmpeg}:
4894 ffmpeg -i in.avi -vf "hflip" out.avi
4898 This filter applies a global color histogram equalization on a
4901 It can be used to correct video that has a compressed range of pixel
4902 intensities. The filter redistributes the pixel intensities to
4903 equalize their distribution across the intensity range. It may be
4904 viewed as an "automatically adjusting contrast filter". This filter is
4905 useful only for correcting degraded or poorly captured source
4908 The filter accepts the following options:
4912 Determine the amount of equalization to be applied. As the strength
4913 is reduced, the distribution of pixel intensities more-and-more
4914 approaches that of the input frame. The value must be a float number
4915 in the range [0,1] and defaults to 0.200.
4918 Set the maximum intensity that can generated and scale the output
4919 values appropriately. The strength should be set as desired and then
4920 the intensity can be limited if needed to avoid washing-out. The value
4921 must be a float number in the range [0,1] and defaults to 0.210.
4924 Set the antibanding level. If enabled the filter will randomly vary
4925 the luminance of output pixels by a small amount to avoid banding of
4926 the histogram. Possible values are @code{none}, @code{weak} or
4927 @code{strong}. It defaults to @code{none}.
4932 Compute and draw a color distribution histogram for the input video.
4934 The computed histogram is a representation of distribution of color components
4937 The filter accepts the following options:
4943 It accepts the following values:
4946 standard histogram that display color components distribution in an image.
4947 Displays color graph for each color component. Shows distribution
4948 of the Y, U, V, A or R, G, B components, depending on input format,
4949 in current frame. Bellow each graph is color component scale meter.
4952 chroma values in vectorscope, if brighter more such chroma values are
4953 distributed in an image.
4954 Displays chroma values (U/V color placement) in two dimensional graph
4955 (which is called a vectorscope). It can be used to read of the hue and
4956 saturation of the current frame. At a same time it is a histogram.
4957 The whiter a pixel in the vectorscope, the more pixels of the input frame
4958 correspond to that pixel (that is the more pixels have this chroma value).
4959 The V component is displayed on the horizontal (X) axis, with the leftmost
4960 side being V = 0 and the rightmost side being V = 255.
4961 The U component is displayed on the vertical (Y) axis, with the top
4962 representing U = 0 and the bottom representing U = 255.
4964 The position of a white pixel in the graph corresponds to the chroma value
4965 of a pixel of the input clip. So the graph can be used to read of the
4966 hue (color flavor) and the saturation (the dominance of the hue in the color).
4967 As the hue of a color changes, it moves around the square. At the center of
4968 the square, the saturation is zero, which means that the corresponding pixel
4969 has no color. If you increase the amount of a specific color, while leaving
4970 the other colors unchanged, the saturation increases, and you move towards
4971 the edge of the square.
4974 chroma values in vectorscope, similar as @code{color} but actual chroma values
4978 per row/column color component graph. In row mode graph in the left side represents
4979 color component value 0 and right side represents value = 255. In column mode top
4980 side represents color component value = 0 and bottom side represents value = 255.
4982 Default value is @code{levels}.
4985 Set height of level in @code{levels}. Default value is @code{200}.
4986 Allowed range is [50, 2048].
4989 Set height of color scale in @code{levels}. Default value is @code{12}.
4990 Allowed range is [0, 40].
4993 Set step for @code{waveform} mode. Smaller values are useful to find out how much
4994 of same luminance values across input rows/columns are distributed.
4995 Default value is @code{10}. Allowed range is [1, 255].
4998 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
4999 Default is @code{row}.
5001 @item waveform_mirror
5002 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
5003 means mirrored. In mirrored mode, higher values will be represented on the left
5004 side for @code{row} mode and at the top for @code{column} mode. Default is
5005 @code{0} (unmirrored).
5008 Set display mode for @code{waveform} and @code{levels}.
5009 It accepts the following values:
5012 Display separate graph for the color components side by side in
5013 @code{row} waveform mode or one below other in @code{column} waveform mode
5014 for @code{waveform} histogram mode. For @code{levels} histogram mode
5015 per color component graphs are placed one bellow other.
5017 This display mode in @code{waveform} histogram mode makes it easy to spot
5018 color casts in the highlights and shadows of an image, by comparing the
5019 contours of the top and the bottom of each waveform.
5020 Since whites, grays, and blacks are characterized by
5021 exactly equal amounts of red, green, and blue, neutral areas of the
5022 picture should display three waveforms of roughly equal width/height.
5023 If not, the correction is easy to make by making adjustments to level the
5027 Presents information that's identical to that in the @code{parade}, except
5028 that the graphs representing color components are superimposed directly
5031 This display mode in @code{waveform} histogram mode can make it easier to spot
5032 the relative differences or similarities in overlapping areas of the color
5033 components that are supposed to be identical, such as neutral whites, grays,
5036 Default is @code{parade}.
5039 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
5040 Default is @code{linear}.
5043 @subsection Examples
5048 Calculate and draw histogram:
5050 ffplay -i input -vf histogram
5058 High precision/quality 3d denoise filter. This filter aims to reduce
5059 image noise producing smooth images and making still images really
5060 still. It should enhance compressibility.
5062 It accepts the following optional parameters:
5066 a non-negative float number which specifies spatial luma strength,
5069 @item chroma_spatial
5070 a non-negative float number which specifies spatial chroma strength,
5071 defaults to 3.0*@var{luma_spatial}/4.0
5074 a float number which specifies luma temporal strength, defaults to
5075 6.0*@var{luma_spatial}/4.0
5078 a float number which specifies chroma temporal strength, defaults to
5079 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
5084 Modify the hue and/or the saturation of the input.
5086 This filter accepts the following options:
5090 Specify the hue angle as a number of degrees. It accepts an expression,
5091 and defaults to "0".
5094 Specify the saturation in the [-10,10] range. It accepts an expression and
5098 Specify the hue angle as a number of radians. It accepts an
5099 expression, and defaults to "0".
5102 Specify the brightness in the [-10,10] range. It accepts an expression and
5106 @option{h} and @option{H} are mutually exclusive, and can't be
5107 specified at the same time.
5109 The @option{b}, @option{h}, @option{H} and @option{s} option values are
5110 expressions containing the following constants:
5114 frame count of the input frame starting from 0
5117 presentation timestamp of the input frame expressed in time base units
5120 frame rate of the input video, NAN if the input frame rate is unknown
5123 timestamp expressed in seconds, NAN if the input timestamp is unknown
5126 time base of the input video
5129 @subsection Examples
5133 Set the hue to 90 degrees and the saturation to 1.0:
5139 Same command but expressing the hue in radians:
5145 Rotate hue and make the saturation swing between 0
5146 and 2 over a period of 1 second:
5148 hue="H=2*PI*t: s=sin(2*PI*t)+1"
5152 Apply a 3 seconds saturation fade-in effect starting at 0:
5157 The general fade-in expression can be written as:
5159 hue="s=min(0\, max((t-START)/DURATION\, 1))"
5163 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
5165 hue="s=max(0\, min(1\, (8-t)/3))"
5168 The general fade-out expression can be written as:
5170 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
5175 @subsection Commands
5177 This filter supports the following commands:
5183 Modify the hue and/or the saturation and/or brightness of the input video.
5184 The command accepts the same syntax of the corresponding option.
5186 If the specified expression is not valid, it is kept at its current
5192 Detect video interlacing type.
5194 This filter tries to detect if the input is interlaced or progressive,
5195 top or bottom field first.
5197 The filter accepts the following options:
5201 Set interlacing threshold.
5203 Set progressive threshold.
5208 Deinterleave or interleave fields.
5210 This filter allows to process interlaced images fields without
5211 deinterlacing them. Deinterleaving splits the input frame into 2
5212 fields (so called half pictures). Odd lines are moved to the top
5213 half of the output image, even lines to the bottom half.
5214 You can process (filter) them independently and then re-interleave them.
5216 The filter accepts the following options:
5220 @item chroma_mode, c
5222 Available values for @var{luma_mode}, @var{chroma_mode} and
5223 @var{alpha_mode} are:
5229 @item deinterleave, d
5230 Deinterleave fields, placing one above the other.
5233 Interleave fields. Reverse the effect of deinterleaving.
5235 Default value is @code{none}.
5238 @item chroma_swap, cs
5239 @item alpha_swap, as
5240 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
5245 Simple interlacing filter from progressive contents. This interleaves upper (or
5246 lower) lines from odd frames with lower (or upper) lines from even frames,
5247 halving the frame rate and preserving image height.
5250 Original Original New Frame
5251 Frame 'j' Frame 'j+1' (tff)
5252 ========== =========== ==================
5253 Line 0 --------------------> Frame 'j' Line 0
5254 Line 1 Line 1 ----> Frame 'j+1' Line 1
5255 Line 2 ---------------------> Frame 'j' Line 2
5256 Line 3 Line 3 ----> Frame 'j+1' Line 3
5258 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
5261 It accepts the following optional parameters:
5265 determines whether the interlaced frame is taken from the even (tff - default)
5266 or odd (bff) lines of the progressive frame.
5269 Enable (default) or disable the vertical lowpass filter to avoid twitter
5270 interlacing and reduce moire patterns.
5275 Deinterlace input video by applying Donald Graft's adaptive kernel
5276 deinterling. Work on interlaced parts of a video to produce
5279 The description of the accepted parameters follows.
5283 Set the threshold which affects the filter's tolerance when
5284 determining if a pixel line must be processed. It must be an integer
5285 in the range [0,255] and defaults to 10. A value of 0 will result in
5286 applying the process on every pixels.
5289 Paint pixels exceeding the threshold value to white if set to 1.
5293 Set the fields order. Swap fields if set to 1, leave fields alone if
5297 Enable additional sharpening if set to 1. Default is 0.
5300 Enable twoway sharpening if set to 1. Default is 0.
5303 @subsection Examples
5307 Apply default values:
5309 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
5313 Enable additional sharpening:
5319 Paint processed pixels in white:
5328 Apply a 3D LUT to an input video.
5330 The filter accepts the following options:
5334 Set the 3D LUT file name.
5336 Currently supported formats:
5348 Select interpolation mode.
5350 Available values are:
5354 Use values from the nearest defined point.
5356 Interpolate values using the 8 points defining a cube.
5358 Interpolate values using a tetrahedron.
5362 @section lut, lutrgb, lutyuv
5364 Compute a look-up table for binding each pixel component input value
5365 to an output value, and apply it to input video.
5367 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
5368 to an RGB input video.
5370 These filters accept the following options:
5373 set first pixel component expression
5375 set second pixel component expression
5377 set third pixel component expression
5379 set fourth pixel component expression, corresponds to the alpha component
5382 set red component expression
5384 set green component expression
5386 set blue component expression
5388 alpha component expression
5391 set Y/luminance component expression
5393 set U/Cb component expression
5395 set V/Cr component expression
5398 Each of them specifies the expression to use for computing the lookup table for
5399 the corresponding pixel component values.
5401 The exact component associated to each of the @var{c*} options depends on the
5404 The @var{lut} filter requires either YUV or RGB pixel formats in input,
5405 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
5407 The expressions can contain the following constants and functions:
5412 the input width and height
5415 input value for the pixel component
5418 the input value clipped in the @var{minval}-@var{maxval} range
5421 maximum value for the pixel component
5424 minimum value for the pixel component
5427 the negated value for the pixel component value clipped in the
5428 @var{minval}-@var{maxval} range , it corresponds to the expression
5429 "maxval-clipval+minval"
5432 the computed value in @var{val} clipped in the
5433 @var{minval}-@var{maxval} range
5435 @item gammaval(gamma)
5436 the computed gamma correction value of the pixel component value
5437 clipped in the @var{minval}-@var{maxval} range, corresponds to the
5439 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
5443 All expressions default to "val".
5445 @subsection Examples
5451 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
5452 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
5455 The above is the same as:
5457 lutrgb="r=negval:g=negval:b=negval"
5458 lutyuv="y=negval:u=negval:v=negval"
5468 Remove chroma components, turns the video into a graytone image:
5470 lutyuv="u=128:v=128"
5474 Apply a luma burning effect:
5480 Remove green and blue components:
5486 Set a constant alpha channel value on input:
5488 format=rgba,lutrgb=a="maxval-minval/2"
5492 Correct luminance gamma by a 0.5 factor:
5494 lutyuv=y=gammaval(0.5)
5498 Discard least significant bits of luma:
5500 lutyuv=y='bitand(val, 128+64+32)'
5504 @section mergeplanes
5506 Merge color channel components from several video streams.
5508 The filter accepts up to 4 input streams, and merge selected input
5509 planes to the output video.
5511 This filter accepts the following options:
5514 Set input to output plane mapping. Default is @code{0}.
5516 The mappings is specified as a bitmap. It should be specified as a
5517 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
5518 mapping for the first plane of the output stream. 'A' sets the number of
5519 the input stream to use (from 0 to 3), and 'a' the plane number of the
5520 corresponding input to use (from 0 to 3). The rest of the mappings is
5521 similar, 'Bb' describes the mapping for the output stream second
5522 plane, 'Cc' describes the mapping for the output stream third plane and
5523 'Dd' describes the mapping for the output stream fourth plane.
5526 Set output pixel format. Default is @code{yuva444p}.
5529 @subsection Examples
5533 Merge three gray video streams of same width and height into single video stream:
5535 [a0][a1][a2]mergeplanes=0x001020:yuv444p
5539 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
5541 [a0][a1]mergeplanes=0x00010210:yuva444p
5545 Swap Y and A plane in yuva444p stream:
5547 format=yuva444p,mergeplanes=0x03010200:yuva444p
5551 Swap U and V plane in yuv420p stream:
5553 format=yuv420p,mergeplanes=0x000201:yuv420p
5557 Cast a rgb24 clip to yuv444p:
5559 format=rgb24,mergeplanes=0x000102:yuv444p
5565 Apply motion-compensation deinterlacing.
5567 It needs one field per frame as input and must thus be used together
5568 with yadif=1/3 or equivalent.
5570 This filter accepts the following options:
5573 Set the deinterlacing mode.
5575 It accepts one of the following values:
5580 use iterative motion estimation
5582 like @samp{slow}, but use multiple reference frames.
5584 Default value is @samp{fast}.
5587 Set the picture field parity assumed for the input video. It must be
5588 one of the following values:
5592 assume top field first
5594 assume bottom field first
5597 Default value is @samp{bff}.
5600 Set per-block quantization parameter (QP) used by the internal
5603 Higher values should result in a smoother motion vector field but less
5604 optimal individual vectors. Default value is 1.
5609 Apply an MPlayer filter to the input video.
5611 This filter provides a wrapper around some of the filters of
5614 This wrapper is considered experimental. Some of the wrapped filters
5615 may not work properly and we may drop support for them, as they will
5616 be implemented natively into FFmpeg. Thus you should avoid
5617 depending on them when writing portable scripts.
5619 The filter accepts the parameters:
5620 @var{filter_name}[:=]@var{filter_params}
5622 @var{filter_name} is the name of a supported MPlayer filter,
5623 @var{filter_params} is a string containing the parameters accepted by
5626 The list of the currently supported filters follows:
5637 The parameter syntax and behavior for the listed filters are the same
5638 of the corresponding MPlayer filters. For detailed instructions check
5639 the "VIDEO FILTERS" section in the MPlayer manual.
5641 @subsection Examples
5645 Adjust gamma, brightness, contrast:
5651 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
5655 Drop frames that do not differ greatly from the previous frame in
5656 order to reduce frame rate.
5658 The main use of this filter is for very-low-bitrate encoding
5659 (e.g. streaming over dialup modem), but it could in theory be used for
5660 fixing movies that were inverse-telecined incorrectly.
5662 A description of the accepted options follows.
5666 Set the maximum number of consecutive frames which can be dropped (if
5667 positive), or the minimum interval between dropped frames (if
5668 negative). If the value is 0, the frame is dropped unregarding the
5669 number of previous sequentially dropped frames.
5676 Set the dropping threshold values.
5678 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
5679 represent actual pixel value differences, so a threshold of 64
5680 corresponds to 1 unit of difference for each pixel, or the same spread
5681 out differently over the block.
5683 A frame is a candidate for dropping if no 8x8 blocks differ by more
5684 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
5685 meaning the whole image) differ by more than a threshold of @option{lo}.
5687 Default value for @option{hi} is 64*12, default value for @option{lo} is
5688 64*5, and default value for @option{frac} is 0.33.
5696 This filter accepts an integer in input, if non-zero it negates the
5697 alpha component (if available). The default value in input is 0.
5701 Force libavfilter not to use any of the specified pixel formats for the
5702 input to the next filter.
5704 This filter accepts the following parameters:
5708 A '|'-separated list of pixel format names, for example
5709 "pix_fmts=yuv420p|monow|rgb24".
5713 @subsection Examples
5717 Force libavfilter to use a format different from @var{yuv420p} for the
5718 input to the vflip filter:
5720 noformat=pix_fmts=yuv420p,vflip
5724 Convert the input video to any of the formats not contained in the list:
5726 noformat=yuv420p|yuv444p|yuv410p
5732 Add noise on video input frame.
5734 The filter accepts the following options:
5742 Set noise seed for specific pixel component or all pixel components in case
5743 of @var{all_seed}. Default value is @code{123457}.
5745 @item all_strength, alls
5746 @item c0_strength, c0s
5747 @item c1_strength, c1s
5748 @item c2_strength, c2s
5749 @item c3_strength, c3s
5750 Set noise strength for specific pixel component or all pixel components in case
5751 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
5753 @item all_flags, allf
5758 Set pixel component flags or set flags for all components if @var{all_flags}.
5759 Available values for component flags are:
5762 averaged temporal noise (smoother)
5764 mix random noise with a (semi)regular pattern
5766 temporal noise (noise pattern changes between frames)
5768 uniform noise (gaussian otherwise)
5772 @subsection Examples
5774 Add temporal and uniform noise to input video:
5776 noise=alls=20:allf=t+u
5781 Pass the video source unchanged to the output.
5785 Apply video transform using libopencv.
5787 To enable this filter install libopencv library and headers and
5788 configure FFmpeg with @code{--enable-libopencv}.
5790 This filter accepts the following parameters:
5795 The name of the libopencv filter to apply.
5798 The parameters to pass to the libopencv filter. If not specified the default
5803 Refer to the official libopencv documentation for more precise
5805 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
5807 Follows the list of supported libopencv filters.
5812 Dilate an image by using a specific structuring element.
5813 This filter corresponds to the libopencv function @code{cvDilate}.
5815 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
5817 @var{struct_el} represents a structuring element, and has the syntax:
5818 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
5820 @var{cols} and @var{rows} represent the number of columns and rows of
5821 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
5822 point, and @var{shape} the shape for the structuring element, and
5823 can be one of the values "rect", "cross", "ellipse", "custom".
5825 If the value for @var{shape} is "custom", it must be followed by a
5826 string of the form "=@var{filename}". The file with name
5827 @var{filename} is assumed to represent a binary image, with each
5828 printable character corresponding to a bright pixel. When a custom
5829 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
5830 or columns and rows of the read file are assumed instead.
5832 The default value for @var{struct_el} is "3x3+0x0/rect".
5834 @var{nb_iterations} specifies the number of times the transform is
5835 applied to the image, and defaults to 1.
5837 Follow some example:
5839 # use the default values
5842 # dilate using a structuring element with a 5x5 cross, iterate two times
5843 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
5845 # read the shape from the file diamond.shape, iterate two times
5846 # the file diamond.shape may contain a pattern of characters like this:
5852 # the specified cols and rows are ignored (but not the anchor point coordinates)
5853 ocv=dilate:0x0+2x2/custom=diamond.shape|2
5858 Erode an image by using a specific structuring element.
5859 This filter corresponds to the libopencv function @code{cvErode}.
5861 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
5862 with the same syntax and semantics as the @ref{dilate} filter.
5866 Smooth the input video.
5868 The filter takes the following parameters:
5869 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
5871 @var{type} is the type of smooth filter to apply, and can be one of
5872 the following values: "blur", "blur_no_scale", "median", "gaussian",
5873 "bilateral". The default value is "gaussian".
5875 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
5876 parameters whose meanings depend on smooth type. @var{param1} and
5877 @var{param2} accept integer positive values or 0, @var{param3} and
5878 @var{param4} accept float values.
5880 The default value for @var{param1} is 3, the default value for the
5881 other parameters is 0.
5883 These parameters correspond to the parameters assigned to the
5884 libopencv function @code{cvSmooth}.
5889 Overlay one video on top of another.
5891 It takes two inputs and one output, the first input is the "main"
5892 video on which the second input is overlayed.
5894 This filter accepts the following parameters:
5896 A description of the accepted options follows.
5901 Set the expression for the x and y coordinates of the overlayed video
5902 on the main video. Default value is "0" for both expressions. In case
5903 the expression is invalid, it is set to a huge value (meaning that the
5904 overlay will not be displayed within the output visible area).
5907 Set when the expressions for @option{x}, and @option{y} are evaluated.
5909 It accepts the following values:
5912 only evaluate expressions once during the filter initialization or
5913 when a command is processed
5916 evaluate expressions for each incoming frame
5919 Default value is @samp{frame}.
5922 If set to 1, force the output to terminate when the shortest input
5923 terminates. Default value is 0.
5926 Set the format for the output video.
5928 It accepts the following values:
5940 Default value is @samp{yuv420}.
5942 @item rgb @emph{(deprecated)}
5943 If set to 1, force the filter to accept inputs in the RGB
5944 color space. Default value is 0. This option is deprecated, use
5945 @option{format} instead.
5948 If set to 1, force the filter to draw the last overlay frame over the
5949 main input until the end of the stream. A value of 0 disables this
5950 behavior. Default value is 1.
5953 The @option{x}, and @option{y} expressions can contain the following
5959 main input width and height
5963 overlay input width and height
5967 the computed values for @var{x} and @var{y}. They are evaluated for
5972 horizontal and vertical chroma subsample values of the output
5973 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
5977 the number of input frame, starting from 0
5980 the position in the file of the input frame, NAN if unknown
5983 timestamp expressed in seconds, NAN if the input timestamp is unknown
5986 Note that the @var{n}, @var{pos}, @var{t} variables are available only
5987 when evaluation is done @emph{per frame}, and will evaluate to NAN
5988 when @option{eval} is set to @samp{init}.
5990 Be aware that frames are taken from each input video in timestamp
5991 order, hence, if their initial timestamps differ, it is a good idea
5992 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
5993 have them begin in the same zero timestamp, as it does the example for
5994 the @var{movie} filter.
5996 You can chain together more overlays but you should test the
5997 efficiency of such approach.
5999 @subsection Commands
6001 This filter supports the following commands:
6005 Modify the x and y of the overlay input.
6006 The command accepts the same syntax of the corresponding option.
6008 If the specified expression is not valid, it is kept at its current
6012 @subsection Examples
6016 Draw the overlay at 10 pixels from the bottom right corner of the main
6019 overlay=main_w-overlay_w-10:main_h-overlay_h-10
6022 Using named options the example above becomes:
6024 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
6028 Insert a transparent PNG logo in the bottom left corner of the input,
6029 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
6031 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
6035 Insert 2 different transparent PNG logos (second logo on bottom
6036 right corner) using the @command{ffmpeg} tool:
6038 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
6042 Add a transparent color layer on top of the main video, @code{WxH}
6043 must specify the size of the main input to the overlay filter:
6045 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
6049 Play an original video and a filtered version (here with the deshake
6050 filter) side by side using the @command{ffplay} tool:
6052 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
6055 The above command is the same as:
6057 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
6061 Make a sliding overlay appearing from the left to the right top part of the
6062 screen starting since time 2:
6064 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
6068 Compose output by putting two input videos side to side:
6070 ffmpeg -i left.avi -i right.avi -filter_complex "
6071 nullsrc=size=200x100 [background];
6072 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
6073 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
6074 [background][left] overlay=shortest=1 [background+left];
6075 [background+left][right] overlay=shortest=1:x=100 [left+right]
6080 Chain several overlays in cascade:
6082 nullsrc=s=200x200 [bg];
6083 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
6084 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
6085 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
6086 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
6087 [in3] null, [mid2] overlay=100:100 [out0]
6094 Apply Overcomplete Wavelet denoiser.
6096 The filter accepts the following options:
6102 Larger depth values will denoise lower frequency components more, but
6103 slow down filtering.
6105 Must be an int in the range 8-16, default is @code{8}.
6107 @item luma_strength, ls
6110 Must be a double value in the range 0-1000, default is @code{1.0}.
6112 @item chroma_strength, cs
6113 Set chroma strength.
6115 Must be a double value in the range 0-1000, default is @code{1.0}.
6120 Add paddings to the input image, and place the original input at the
6121 given coordinates @var{x}, @var{y}.
6123 This filter accepts the following parameters:
6128 Specify an expression for the size of the output image with the
6129 paddings added. If the value for @var{width} or @var{height} is 0, the
6130 corresponding input size is used for the output.
6132 The @var{width} expression can reference the value set by the
6133 @var{height} expression, and vice versa.
6135 The default value of @var{width} and @var{height} is 0.
6139 Specify an expression for the offsets where to place the input image
6140 in the padded area with respect to the top/left border of the output
6143 The @var{x} expression can reference the value set by the @var{y}
6144 expression, and vice versa.
6146 The default value of @var{x} and @var{y} is 0.
6149 Specify the color of the padded area. For the syntax of this option,
6150 check the "Color" section in the ffmpeg-utils manual.
6152 The default value of @var{color} is "black".
6155 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
6156 options are expressions containing the following constants:
6161 the input video width and height
6165 same as @var{in_w} and @var{in_h}
6169 the output width and height, that is the size of the padded area as
6170 specified by the @var{width} and @var{height} expressions
6174 same as @var{out_w} and @var{out_h}
6178 x and y offsets as specified by the @var{x} and @var{y}
6179 expressions, or NAN if not yet specified
6182 same as @var{iw} / @var{ih}
6185 input sample aspect ratio
6188 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
6192 horizontal and vertical chroma subsample values. For example for the
6193 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6196 @subsection Examples
6200 Add paddings with color "violet" to the input video. Output video
6201 size is 640x480, the top-left corner of the input video is placed at
6204 pad=640:480:0:40:violet
6207 The example above is equivalent to the following command:
6209 pad=width=640:height=480:x=0:y=40:color=violet
6213 Pad the input to get an output with dimensions increased by 3/2,
6214 and put the input video at the center of the padded area:
6216 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
6220 Pad the input to get a squared output with size equal to the maximum
6221 value between the input width and height, and put the input video at
6222 the center of the padded area:
6224 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
6228 Pad the input to get a final w/h ratio of 16:9:
6230 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
6234 In case of anamorphic video, in order to set the output display aspect
6235 correctly, it is necessary to use @var{sar} in the expression,
6236 according to the relation:
6238 (ih * X / ih) * sar = output_dar
6239 X = output_dar / sar
6242 Thus the previous example needs to be modified to:
6244 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
6248 Double output size and put the input video in the bottom-right
6249 corner of the output padded area:
6251 pad="2*iw:2*ih:ow-iw:oh-ih"
6255 @section perspective
6257 Correct perspective of video not recorded perpendicular to the screen.
6259 A description of the accepted parameters follows.
6270 Set coordinates expression for top left, top right, bottom left and bottom right corners.
6271 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
6273 The expressions can use the following variables:
6278 the width and height of video frame.
6282 Set interpolation for perspective correction.
6284 It accepts the following values:
6290 Default value is @samp{linear}.
6295 Delay interlaced video by one field time so that the field order changes.
6297 The intended use is to fix PAL movies that have been captured with the
6298 opposite field order to the film-to-video transfer.
6300 A description of the accepted parameters follows.
6306 It accepts the following values:
6309 Capture field order top-first, transfer bottom-first.
6310 Filter will delay the bottom field.
6313 Capture field order bottom-first, transfer top-first.
6314 Filter will delay the top field.
6317 Capture and transfer with the same field order. This mode only exists
6318 for the documentation of the other options to refer to, but if you
6319 actually select it, the filter will faithfully do nothing.
6322 Capture field order determined automatically by field flags, transfer
6324 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
6325 basis using field flags. If no field information is available,
6326 then this works just like @samp{u}.
6329 Capture unknown or varying, transfer opposite.
6330 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
6331 analyzing the images and selecting the alternative that produces best
6332 match between the fields.
6335 Capture top-first, transfer unknown or varying.
6336 Filter selects among @samp{t} and @samp{p} using image analysis.
6339 Capture bottom-first, transfer unknown or varying.
6340 Filter selects among @samp{b} and @samp{p} using image analysis.
6343 Capture determined by field flags, transfer unknown or varying.
6344 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
6345 image analysis. If no field information is available, then this works just
6346 like @samp{U}. This is the default mode.
6349 Both capture and transfer unknown or varying.
6350 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
6354 @section pixdesctest
6356 Pixel format descriptor test filter, mainly useful for internal
6357 testing. The output video should be equal to the input video.
6361 format=monow, pixdesctest
6364 can be used to test the monowhite pixel format descriptor definition.
6368 Enable the specified chain of postprocessing subfilters using libpostproc. This
6369 library should be automatically selected with a GPL build (@code{--enable-gpl}).
6370 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
6371 Each subfilter and some options have a short and a long name that can be used
6372 interchangeably, i.e. dr/dering are the same.
6374 The filters accept the following options:
6378 Set postprocessing subfilters string.
6381 All subfilters share common options to determine their scope:
6385 Honor the quality commands for this subfilter.
6388 Do chrominance filtering, too (default).
6391 Do luminance filtering only (no chrominance).
6394 Do chrominance filtering only (no luminance).
6397 These options can be appended after the subfilter name, separated by a '|'.
6399 Available subfilters are:
6402 @item hb/hdeblock[|difference[|flatness]]
6403 Horizontal deblocking filter
6406 Difference factor where higher values mean more deblocking (default: @code{32}).
6408 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6411 @item vb/vdeblock[|difference[|flatness]]
6412 Vertical deblocking filter
6415 Difference factor where higher values mean more deblocking (default: @code{32}).
6417 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6420 @item ha/hadeblock[|difference[|flatness]]
6421 Accurate horizontal deblocking filter
6424 Difference factor where higher values mean more deblocking (default: @code{32}).
6426 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6429 @item va/vadeblock[|difference[|flatness]]
6430 Accurate vertical deblocking filter
6433 Difference factor where higher values mean more deblocking (default: @code{32}).
6435 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6439 The horizontal and vertical deblocking filters share the difference and
6440 flatness values so you cannot set different horizontal and vertical
6445 Experimental horizontal deblocking filter
6448 Experimental vertical deblocking filter
6453 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
6456 larger -> stronger filtering
6458 larger -> stronger filtering
6460 larger -> stronger filtering
6463 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
6466 Stretch luminance to @code{0-255}.
6469 @item lb/linblenddeint
6470 Linear blend deinterlacing filter that deinterlaces the given block by
6471 filtering all lines with a @code{(1 2 1)} filter.
6473 @item li/linipoldeint
6474 Linear interpolating deinterlacing filter that deinterlaces the given block by
6475 linearly interpolating every second line.
6477 @item ci/cubicipoldeint
6478 Cubic interpolating deinterlacing filter deinterlaces the given block by
6479 cubically interpolating every second line.
6481 @item md/mediandeint
6482 Median deinterlacing filter that deinterlaces the given block by applying a
6483 median filter to every second line.
6485 @item fd/ffmpegdeint
6486 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
6487 second line with a @code{(-1 4 2 4 -1)} filter.
6490 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
6491 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
6493 @item fq/forceQuant[|quantizer]
6494 Overrides the quantizer table from the input with the constant quantizer you
6502 Default pp filter combination (@code{hb|a,vb|a,dr|a})
6505 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
6508 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
6511 @subsection Examples
6515 Apply horizontal and vertical deblocking, deringing and automatic
6516 brightness/contrast:
6522 Apply default filters without brightness/contrast correction:
6528 Apply default filters and temporal denoiser:
6530 pp=default/tmpnoise|1|2|3
6534 Apply deblocking on luminance only, and switch vertical deblocking on or off
6535 automatically depending on available CPU time:
6543 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
6544 Ratio) between two input videos.
6546 This filter takes in input two input videos, the first input is
6547 considered the "main" source and is passed unchanged to the
6548 output. The second input is used as a "reference" video for computing
6551 Both video inputs must have the same resolution and pixel format for
6552 this filter to work correctly. Also it assumes that both inputs
6553 have the same number of frames, which are compared one by one.
6555 The obtained average PSNR is printed through the logging system.
6557 The filter stores the accumulated MSE (mean squared error) of each
6558 frame, and at the end of the processing it is averaged across all frames
6559 equally, and the following formula is applied to obtain the PSNR:
6562 PSNR = 10*log10(MAX^2/MSE)
6565 Where MAX is the average of the maximum values of each component of the
6568 The description of the accepted parameters follows.
6572 If specified the filter will use the named file to save the PSNR of
6573 each individual frame.
6576 The file printed if @var{stats_file} is selected, contains a sequence of
6577 key/value pairs of the form @var{key}:@var{value} for each compared
6580 A description of each shown parameter follows:
6584 sequential number of the input frame, starting from 1
6587 Mean Square Error pixel-by-pixel average difference of the compared
6588 frames, averaged over all the image components.
6590 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
6591 Mean Square Error pixel-by-pixel average difference of the compared
6592 frames for the component specified by the suffix.
6594 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
6595 Peak Signal to Noise ratio of the compared frames for the component
6596 specified by the suffix.
6601 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
6602 [main][ref] psnr="stats_file=stats.log" [out]
6605 On this example the input file being processed is compared with the
6606 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
6607 is stored in @file{stats.log}.
6611 Pulldown reversal (inverse telecine) filter, capable of handling mixed
6612 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
6615 The pullup filter is designed to take advantage of future context in making
6616 its decisions. This filter is stateless in the sense that it does not lock
6617 onto a pattern to follow, but it instead looks forward to the following
6618 fields in order to identify matches and rebuild progressive frames.
6620 To produce content with an even framerate, insert the fps filter after
6621 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
6622 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
6624 The filter accepts the following options:
6631 These options set the amount of "junk" to ignore at the left, right, top, and
6632 bottom of the image, respectively. Left and right are in units of 8 pixels,
6633 while top and bottom are in units of 2 lines.
6634 The default is 8 pixels on each side.
6637 Set the strict breaks. Setting this option to 1 will reduce the chances of
6638 filter generating an occasional mismatched frame, but it may also cause an
6639 excessive number of frames to be dropped during high motion sequences.
6640 Conversely, setting it to -1 will make filter match fields more easily.
6641 This may help processing of video where there is slight blurring between
6642 the fields, but may also cause there to be interlaced frames in the output.
6643 Default value is @code{0}.
6646 Set the metric plane to use. It accepts the following values:
6652 Use chroma blue plane.
6655 Use chroma red plane.
6658 This option may be set to use chroma plane instead of the default luma plane
6659 for doing filter's computations. This may improve accuracy on very clean
6660 source material, but more likely will decrease accuracy, especially if there
6661 is chroma noise (rainbow effect) or any grayscale video.
6662 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
6663 load and make pullup usable in realtime on slow machines.
6666 For best results (without duplicated frames in the output file) it is
6667 necessary to change the output frame rate. For example, to inverse
6668 telecine NTSC input:
6670 ffmpeg -i input -vf pullup -r 24000/1001 ...
6675 Suppress a TV station logo, using an image file to determine which
6676 pixels comprise the logo. It works by filling in the pixels that
6677 comprise the logo with neighboring pixels.
6679 The filter accepts the following options:
6683 Set the filter bitmap file, which can be any image format supported by
6684 libavformat. The width and height of the image file must match those of the
6685 video stream being processed.
6688 Pixels in the provided bitmap image with a value of zero are not
6689 considered part of the logo, non-zero pixels are considered part of
6690 the logo. If you use white (255) for the logo and black (0) for the
6691 rest, you will be safe. For making the filter bitmap, it is
6692 recommended to take a screen capture of a black frame with the logo
6693 visible, and then using a threshold filter followed by the erode
6694 filter once or twice.
6696 If needed, little splotches can be fixed manually. Remember that if
6697 logo pixels are not covered, the filter quality will be much
6698 reduced. Marking too many pixels as part of the logo does not hurt as
6699 much, but it will increase the amount of blurring needed to cover over
6700 the image and will destroy more information than necessary, and extra
6701 pixels will slow things down on a large logo.
6705 Rotate video by an arbitrary angle expressed in radians.
6707 The filter accepts the following options:
6709 A description of the optional parameters follows.
6712 Set an expression for the angle by which to rotate the input video
6713 clockwise, expressed as a number of radians. A negative value will
6714 result in a counter-clockwise rotation. By default it is set to "0".
6716 This expression is evaluated for each frame.
6719 Set the output width expression, default value is "iw".
6720 This expression is evaluated just once during configuration.
6723 Set the output height expression, default value is "ih".
6724 This expression is evaluated just once during configuration.
6727 Enable bilinear interpolation if set to 1, a value of 0 disables
6728 it. Default value is 1.
6731 Set the color used to fill the output area not covered by the rotated
6732 image. For the generalsyntax of this option, check the "Color" section in the
6733 ffmpeg-utils manual. If the special value "none" is selected then no
6734 background is printed (useful for example if the background is never shown).
6736 Default value is "black".
6739 The expressions for the angle and the output size can contain the
6740 following constants and functions:
6744 sequential number of the input frame, starting from 0. It is always NAN
6745 before the first frame is filtered.
6748 time in seconds of the input frame, it is set to 0 when the filter is
6749 configured. It is always NAN before the first frame is filtered.
6753 horizontal and vertical chroma subsample values. For example for the
6754 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6758 the input video width and heigth
6762 the output width and heigth, that is the size of the padded area as
6763 specified by the @var{width} and @var{height} expressions
6767 the minimal width/height required for completely containing the input
6768 video rotated by @var{a} radians.
6770 These are only available when computing the @option{out_w} and
6771 @option{out_h} expressions.
6774 @subsection Examples
6778 Rotate the input by PI/6 radians clockwise:
6784 Rotate the input by PI/6 radians counter-clockwise:
6790 Rotate the input by 45 degrees clockwise:
6796 Apply a constant rotation with period T, starting from an angle of PI/3:
6798 rotate=PI/3+2*PI*t/T
6802 Make the input video rotation oscillating with a period of T
6803 seconds and an amplitude of A radians:
6805 rotate=A*sin(2*PI/T*t)
6809 Rotate the video, output size is choosen so that the whole rotating
6810 input video is always completely contained in the output:
6812 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
6816 Rotate the video, reduce the output size so that no background is ever
6819 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
6823 @subsection Commands
6825 The filter supports the following commands:
6829 Set the angle expression.
6830 The command accepts the same syntax of the corresponding option.
6832 If the specified expression is not valid, it is kept at its current
6838 Apply Shape Adaptive Blur.
6840 The filter accepts the following options:
6843 @item luma_radius, lr
6844 Set luma blur filter strength, must be a value in range 0.1-4.0, default
6845 value is 1.0. A greater value will result in a more blurred image, and
6846 in slower processing.
6848 @item luma_pre_filter_radius, lpfr
6849 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
6852 @item luma_strength, ls
6853 Set luma maximum difference between pixels to still be considered, must
6854 be a value in the 0.1-100.0 range, default value is 1.0.
6856 @item chroma_radius, cr
6857 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
6858 greater value will result in a more blurred image, and in slower
6861 @item chroma_pre_filter_radius, cpfr
6862 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
6864 @item chroma_strength, cs
6865 Set chroma maximum difference between pixels to still be considered,
6866 must be a value in the 0.1-100.0 range.
6869 Each chroma option value, if not explicitly specified, is set to the
6870 corresponding luma option value.
6875 Scale (resize) the input video, using the libswscale library.
6877 The scale filter forces the output display aspect ratio to be the same
6878 of the input, by changing the output sample aspect ratio.
6880 If the input image format is different from the format requested by
6881 the next filter, the scale filter will convert the input to the
6885 The filter accepts the following options, or any of the options
6886 supported by the libswscale scaler.
6888 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
6889 the complete list of scaler options.
6894 Set the output video dimension expression. Default value is the input
6897 If the value is 0, the input width is used for the output.
6899 If one of the values is -1, the scale filter will use a value that
6900 maintains the aspect ratio of the input image, calculated from the
6901 other specified dimension. If both of them are -1, the input size is
6904 See below for the list of accepted constants for use in the dimension
6908 Set the interlacing mode. It accepts the following values:
6912 Force interlaced aware scaling.
6915 Do not apply interlaced scaling.
6918 Select interlaced aware scaling depending on whether the source frames
6919 are flagged as interlaced or not.
6922 Default value is @samp{0}.
6925 Set libswscale scaling flags. See
6926 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
6927 complete list of values. If not explictly specified the filter applies
6931 Set the video size. For the syntax of this option, check the "Video size"
6932 section in the ffmpeg-utils manual.
6934 @item in_color_matrix
6935 @item out_color_matrix
6936 Set in/output YCbCr color space type.
6938 This allows the autodetected value to be overridden as well as allows forcing
6939 a specific value used for the output and encoder.
6941 If not specified, the color space type depends on the pixel format.
6947 Choose automatically.
6950 Format conforming to International Telecommunication Union (ITU)
6951 Recommendation BT.709.
6954 Set color space conforming to the United States Federal Communications
6955 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
6958 Set color space conforming to:
6962 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
6965 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
6968 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
6973 Set color space conforming to SMPTE ST 240:1999.
6978 Set in/output YCbCr sample range.
6980 This allows the autodetected value to be overridden as well as allows forcing
6981 a specific value used for the output and encoder. If not specified, the
6982 range depends on the pixel format. Possible values:
6986 Choose automatically.
6989 Set full range (0-255 in case of 8-bit luma).
6992 Set "MPEG" range (16-235 in case of 8-bit luma).
6995 @item force_original_aspect_ratio
6996 Enable decreasing or increasing output video width or height if necessary to
6997 keep the original aspect ratio. Possible values:
7001 Scale the video as specified and disable this feature.
7004 The output video dimensions will automatically be decreased if needed.
7007 The output video dimensions will automatically be increased if needed.
7011 One useful instance of this option is that when you know a specific device's
7012 maximum allowed resolution, you can use this to limit the output video to
7013 that, while retaining the aspect ratio. For example, device A allows
7014 1280x720 playback, and your video is 1920x800. Using this option (set it to
7015 decrease) and specifying 1280x720 to the command line makes the output
7018 Please note that this is a different thing than specifying -1 for @option{w}
7019 or @option{h}, you still need to specify the output resolution for this option
7024 The values of the @option{w} and @option{h} options are expressions
7025 containing the following constants:
7030 the input width and height
7034 same as @var{in_w} and @var{in_h}
7038 the output (scaled) width and height
7042 same as @var{out_w} and @var{out_h}
7045 same as @var{iw} / @var{ih}
7048 input sample aspect ratio
7051 input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
7055 horizontal and vertical input chroma subsample values. For example for the
7056 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7060 horizontal and vertical output chroma subsample values. For example for the
7061 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7064 @subsection Examples
7068 Scale the input video to a size of 200x100:
7073 This is equivalent to:
7084 Specify a size abbreviation for the output size:
7089 which can also be written as:
7095 Scale the input to 2x:
7101 The above is the same as:
7107 Scale the input to 2x with forced interlaced scaling:
7109 scale=2*iw:2*ih:interl=1
7113 Scale the input to half size:
7119 Increase the width, and set the height to the same size:
7125 Seek for Greek harmony:
7132 Increase the height, and set the width to 3/2 of the height:
7134 scale=w=3/2*oh:h=3/5*ih
7138 Increase the size, but make the size a multiple of the chroma
7141 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
7145 Increase the width to a maximum of 500 pixels, keep the same input
7148 scale=w='min(500\, iw*3/2):h=-1'
7152 @section separatefields
7154 The @code{separatefields} takes a frame-based video input and splits
7155 each frame into its components fields, producing a new half height clip
7156 with twice the frame rate and twice the frame count.
7158 This filter use field-dominance information in frame to decide which
7159 of each pair of fields to place first in the output.
7160 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
7162 @section setdar, setsar
7164 The @code{setdar} filter sets the Display Aspect Ratio for the filter
7167 This is done by changing the specified Sample (aka Pixel) Aspect
7168 Ratio, according to the following equation:
7170 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
7173 Keep in mind that the @code{setdar} filter does not modify the pixel
7174 dimensions of the video frame. Also the display aspect ratio set by
7175 this filter may be changed by later filters in the filterchain,
7176 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
7179 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
7180 the filter output video.
7182 Note that as a consequence of the application of this filter, the
7183 output display aspect ratio will change according to the equation
7186 Keep in mind that the sample aspect ratio set by the @code{setsar}
7187 filter may be changed by later filters in the filterchain, e.g. if
7188 another "setsar" or a "setdar" filter is applied.
7190 The filters accept the following options:
7193 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
7194 Set the aspect ratio used by the filter.
7196 The parameter can be a floating point number string, an expression, or
7197 a string of the form @var{num}:@var{den}, where @var{num} and
7198 @var{den} are the numerator and denominator of the aspect ratio. If
7199 the parameter is not specified, it is assumed the value "0".
7200 In case the form "@var{num}:@var{den}" is used, the @code{:} character
7204 Set the maximum integer value to use for expressing numerator and
7205 denominator when reducing the expressed aspect ratio to a rational.
7206 Default value is @code{100}.
7210 The parameter @var{sar} is an expression containing
7211 the following constants:
7215 the corresponding mathematical approximated values for e
7216 (euler number), pi (greek PI), phi (golden ratio)
7219 the input width and height
7222 same as @var{w} / @var{h}
7225 input sample aspect ratio
7228 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
7231 horizontal and vertical chroma subsample values. For example for the
7232 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7235 @subsection Examples
7240 To change the display aspect ratio to 16:9, specify one of the following:
7248 To change the sample aspect ratio to 10:11, specify:
7254 To set a display aspect ratio of 16:9, and specify a maximum integer value of
7255 1000 in the aspect ratio reduction, use the command:
7257 setdar=ratio=16/9:max=1000
7265 Force field for the output video frame.
7267 The @code{setfield} filter marks the interlace type field for the
7268 output frames. It does not change the input frame, but only sets the
7269 corresponding property, which affects how the frame is treated by
7270 following filters (e.g. @code{fieldorder} or @code{yadif}).
7272 The filter accepts the following options:
7277 Available values are:
7281 Keep the same field property.
7284 Mark the frame as bottom-field-first.
7287 Mark the frame as top-field-first.
7290 Mark the frame as progressive.
7296 Show a line containing various information for each input video frame.
7297 The input video is not modified.
7299 The shown line contains a sequence of key/value pairs of the form
7300 @var{key}:@var{value}.
7302 A description of each shown parameter follows:
7306 sequential number of the input frame, starting from 0
7309 Presentation TimeStamp of the input frame, expressed as a number of
7310 time base units. The time base unit depends on the filter input pad.
7313 Presentation TimeStamp of the input frame, expressed as a number of
7317 position of the frame in the input stream, -1 if this information in
7318 unavailable and/or meaningless (for example in case of synthetic video)
7324 sample aspect ratio of the input frame, expressed in the form
7328 size of the input frame. For the syntax of this option, check the "Video size"
7329 section in the ffmpeg-utils manual.
7332 interlaced mode ("P" for "progressive", "T" for top field first, "B"
7333 for bottom field first)
7336 1 if the frame is a key frame, 0 otherwise
7339 picture type of the input frame ("I" for an I-frame, "P" for a
7340 P-frame, "B" for a B-frame, "?" for unknown type).
7341 Check also the documentation of the @code{AVPictureType} enum and of
7342 the @code{av_get_picture_type_char} function defined in
7343 @file{libavutil/avutil.h}.
7346 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
7348 @item plane_checksum
7349 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
7350 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
7356 Blur the input video without impacting the outlines.
7358 The filter accepts the following options:
7361 @item luma_radius, lr
7362 Set the luma radius. The option value must be a float number in
7363 the range [0.1,5.0] that specifies the variance of the gaussian filter
7364 used to blur the image (slower if larger). Default value is 1.0.
7366 @item luma_strength, ls
7367 Set the luma strength. The option value must be a float number
7368 in the range [-1.0,1.0] that configures the blurring. A value included
7369 in [0.0,1.0] will blur the image whereas a value included in
7370 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7372 @item luma_threshold, lt
7373 Set the luma threshold used as a coefficient to determine
7374 whether a pixel should be blurred or not. The option value must be an
7375 integer in the range [-30,30]. A value of 0 will filter all the image,
7376 a value included in [0,30] will filter flat areas and a value included
7377 in [-30,0] will filter edges. Default value is 0.
7379 @item chroma_radius, cr
7380 Set the chroma radius. The option value must be a float number in
7381 the range [0.1,5.0] that specifies the variance of the gaussian filter
7382 used to blur the image (slower if larger). Default value is 1.0.
7384 @item chroma_strength, cs
7385 Set the chroma strength. The option value must be a float number
7386 in the range [-1.0,1.0] that configures the blurring. A value included
7387 in [0.0,1.0] will blur the image whereas a value included in
7388 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7390 @item chroma_threshold, ct
7391 Set the chroma threshold used as a coefficient to determine
7392 whether a pixel should be blurred or not. The option value must be an
7393 integer in the range [-30,30]. A value of 0 will filter all the image,
7394 a value included in [0,30] will filter flat areas and a value included
7395 in [-30,0] will filter edges. Default value is 0.
7398 If a chroma option is not explicitly set, the corresponding luma value
7403 Convert between different stereoscopic image formats.
7405 The filters accept the following options:
7409 Set stereoscopic image format of input.
7411 Available values for input image formats are:
7414 side by side parallel (left eye left, right eye right)
7417 side by side crosseye (right eye left, left eye right)
7420 side by side parallel with half width resolution
7421 (left eye left, right eye right)
7424 side by side crosseye with half width resolution
7425 (right eye left, left eye right)
7428 above-below (left eye above, right eye below)
7431 above-below (right eye above, left eye below)
7434 above-below with half height resolution
7435 (left eye above, right eye below)
7438 above-below with half height resolution
7439 (right eye above, left eye below)
7442 alternating frames (left eye first, right eye second)
7445 alternating frames (right eye first, left eye second)
7447 Default value is @samp{sbsl}.
7451 Set stereoscopic image format of output.
7453 Available values for output image formats are all the input formats as well as:
7456 anaglyph red/blue gray
7457 (red filter on left eye, blue filter on right eye)
7460 anaglyph red/green gray
7461 (red filter on left eye, green filter on right eye)
7464 anaglyph red/cyan gray
7465 (red filter on left eye, cyan filter on right eye)
7468 anaglyph red/cyan half colored
7469 (red filter on left eye, cyan filter on right eye)
7472 anaglyph red/cyan color
7473 (red filter on left eye, cyan filter on right eye)
7476 anaglyph red/cyan color optimized with the least squares projection of dubois
7477 (red filter on left eye, cyan filter on right eye)
7480 anaglyph green/magenta gray
7481 (green filter on left eye, magenta filter on right eye)
7484 anaglyph green/magenta half colored
7485 (green filter on left eye, magenta filter on right eye)
7488 anaglyph green/magenta colored
7489 (green filter on left eye, magenta filter on right eye)
7492 anaglyph green/magenta color optimized with the least squares projection of dubois
7493 (green filter on left eye, magenta filter on right eye)
7496 anaglyph yellow/blue gray
7497 (yellow filter on left eye, blue filter on right eye)
7500 anaglyph yellow/blue half colored
7501 (yellow filter on left eye, blue filter on right eye)
7504 anaglyph yellow/blue colored
7505 (yellow filter on left eye, blue filter on right eye)
7508 anaglyph yellow/blue color optimized with the least squares projection of dubois
7509 (yellow filter on left eye, blue filter on right eye)
7512 interleaved rows (left eye has top row, right eye starts on next row)
7515 interleaved rows (right eye has top row, left eye starts on next row)
7518 mono output (left eye only)
7521 mono output (right eye only)
7524 Default value is @samp{arcd}.
7527 @subsection Examples
7531 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
7537 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
7545 Apply a simple postprocessing filter that compresses and decompresses the image
7546 at several (or - in the case of @option{quality} level @code{6} - all) shifts
7547 and average the results.
7549 The filter accepts the following options:
7553 Set quality. This option defines the number of levels for averaging. It accepts
7554 an integer in the range 0-6. If set to @code{0}, the filter will have no
7555 effect. A value of @code{6} means the higher quality. For each increment of
7556 that value the speed drops by a factor of approximately 2. Default value is
7560 Force a constant quantization parameter. If not set, the filter will use the QP
7561 from the video stream (if available).
7564 Set thresholding mode. Available modes are:
7568 Set hard thresholding (default).
7570 Set soft thresholding (better de-ringing effect, but likely blurrier).
7574 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
7575 option may cause flicker since the B-Frames have often larger QP. Default is
7576 @code{0} (not enabled).
7582 Draw subtitles on top of input video using the libass library.
7584 To enable compilation of this filter you need to configure FFmpeg with
7585 @code{--enable-libass}. This filter also requires a build with libavcodec and
7586 libavformat to convert the passed subtitles file to ASS (Advanced Substation
7587 Alpha) subtitles format.
7589 The filter accepts the following options:
7593 Set the filename of the subtitle file to read. It must be specified.
7596 Specify the size of the original video, the video for which the ASS file
7597 was composed. For the syntax of this option, check the "Video size" section in
7598 the ffmpeg-utils manual. Due to a misdesign in ASS aspect ratio arithmetic,
7599 this is necessary to correctly scale the fonts if the aspect ratio has been
7603 Set subtitles input character encoding. @code{subtitles} filter only. Only
7604 useful if not UTF-8.
7607 If the first key is not specified, it is assumed that the first value
7608 specifies the @option{filename}.
7610 For example, to render the file @file{sub.srt} on top of the input
7611 video, use the command:
7616 which is equivalent to:
7618 subtitles=filename=sub.srt
7623 Scale the input by 2x and smooth using the Super2xSaI (Scale and
7624 Interpolate) pixel art scaling algorithm.
7626 Useful for enlarging pixel art images without reducing sharpness.
7633 Apply telecine process to the video.
7635 This filter accepts the following options:
7644 The default value is @code{top}.
7648 A string of numbers representing the pulldown pattern you wish to apply.
7649 The default value is @code{23}.
7653 Some typical patterns:
7658 24p: 2332 (preferred)
7665 24p: 222222222223 ("Euro pulldown")
7671 Select the most representative frame in a given sequence of consecutive frames.
7673 The filter accepts the following options:
7677 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
7678 will pick one of them, and then handle the next batch of @var{n} frames until
7679 the end. Default is @code{100}.
7682 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
7683 value will result in a higher memory usage, so a high value is not recommended.
7685 @subsection Examples
7689 Extract one picture each 50 frames:
7695 Complete example of a thumbnail creation with @command{ffmpeg}:
7697 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
7703 Tile several successive frames together.
7705 The filter accepts the following options:
7710 Set the grid size (i.e. the number of lines and columns). For the syntax of
7711 this option, check the "Video size" section in the ffmpeg-utils manual.
7714 Set the maximum number of frames to render in the given area. It must be less
7715 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
7716 the area will be used.
7719 Set the outer border margin in pixels.
7722 Set the inner border thickness (i.e. the number of pixels between frames). For
7723 more advanced padding options (such as having different values for the edges),
7724 refer to the pad video filter.
7727 Specify the color of the unused areaFor the syntax of this option, check the
7728 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
7732 @subsection Examples
7736 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
7738 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
7740 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
7741 duplicating each output frame to accomodate the originally detected frame
7745 Display @code{5} pictures in an area of @code{3x2} frames,
7746 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
7747 mixed flat and named options:
7749 tile=3x2:nb_frames=5:padding=7:margin=2
7755 Perform various types of temporal field interlacing.
7757 Frames are counted starting from 1, so the first input frame is
7760 The filter accepts the following options:
7765 Specify the mode of the interlacing. This option can also be specified
7766 as a value alone. See below for a list of values for this option.
7768 Available values are:
7772 Move odd frames into the upper field, even into the lower field,
7773 generating a double height frame at half frame rate.
7776 Only output even frames, odd frames are dropped, generating a frame with
7777 unchanged height at half frame rate.
7780 Only output odd frames, even frames are dropped, generating a frame with
7781 unchanged height at half frame rate.
7784 Expand each frame to full height, but pad alternate lines with black,
7785 generating a frame with double height at the same input frame rate.
7787 @item interleave_top, 4
7788 Interleave the upper field from odd frames with the lower field from
7789 even frames, generating a frame with unchanged height at half frame rate.
7791 @item interleave_bottom, 5
7792 Interleave the lower field from odd frames with the upper field from
7793 even frames, generating a frame with unchanged height at half frame rate.
7795 @item interlacex2, 6
7796 Double frame rate with unchanged height. Frames are inserted each
7797 containing the second temporal field from the previous input frame and
7798 the first temporal field from the next input frame. This mode relies on
7799 the top_field_first flag. Useful for interlaced video displays with no
7800 field synchronisation.
7803 Numeric values are deprecated but are accepted for backward
7804 compatibility reasons.
7806 Default mode is @code{merge}.
7809 Specify flags influencing the filter process.
7811 Available value for @var{flags} is:
7814 @item low_pass_filter, vlfp
7815 Enable vertical low-pass filtering in the filter.
7816 Vertical low-pass filtering is required when creating an interlaced
7817 destination from a progressive source which contains high-frequency
7818 vertical detail. Filtering will reduce interlace 'twitter' and Moire
7821 Vertical low-pass filtering can only be enabled for @option{mode}
7822 @var{interleave_top} and @var{interleave_bottom}.
7829 Transpose rows with columns in the input video and optionally flip it.
7831 This filter accepts the following options:
7836 Specify the transposition direction.
7838 Can assume the following values:
7840 @item 0, 4, cclock_flip
7841 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
7849 Rotate by 90 degrees clockwise, that is:
7857 Rotate by 90 degrees counterclockwise, that is:
7864 @item 3, 7, clock_flip
7865 Rotate by 90 degrees clockwise and vertically flip, that is:
7873 For values between 4-7, the transposition is only done if the input
7874 video geometry is portrait and not landscape. These values are
7875 deprecated, the @code{passthrough} option should be used instead.
7877 Numerical values are deprecated, and should be dropped in favor of
7881 Do not apply the transposition if the input geometry matches the one
7882 specified by the specified value. It accepts the following values:
7885 Always apply transposition.
7887 Preserve portrait geometry (when @var{height} >= @var{width}).
7889 Preserve landscape geometry (when @var{width} >= @var{height}).
7892 Default value is @code{none}.
7895 For example to rotate by 90 degrees clockwise and preserve portrait
7898 transpose=dir=1:passthrough=portrait
7901 The command above can also be specified as:
7903 transpose=1:portrait
7907 Trim the input so that the output contains one continuous subpart of the input.
7909 This filter accepts the following options:
7912 Specify time of the start of the kept section, i.e. the frame with the
7913 timestamp @var{start} will be the first frame in the output.
7916 Specify time of the first frame that will be dropped, i.e. the frame
7917 immediately preceding the one with the timestamp @var{end} will be the last
7918 frame in the output.
7921 Same as @var{start}, except this option sets the start timestamp in timebase
7922 units instead of seconds.
7925 Same as @var{end}, except this option sets the end timestamp in timebase units
7929 Specify maximum duration of the output.
7932 Number of the first frame that should be passed to output.
7935 Number of the first frame that should be dropped.
7938 @option{start}, @option{end}, @option{duration} are expressed as time
7939 duration specifications, check the "Time duration" section in the
7940 ffmpeg-utils manual.
7942 Note that the first two sets of the start/end options and the @option{duration}
7943 option look at the frame timestamp, while the _frame variants simply count the
7944 frames that pass through the filter. Also note that this filter does not modify
7945 the timestamps. If you wish that the output timestamps start at zero, insert a
7946 setpts filter after the trim filter.
7948 If multiple start or end options are set, this filter tries to be greedy and
7949 keep all the frames that match at least one of the specified constraints. To keep
7950 only the part that matches all the constraints at once, chain multiple trim
7953 The defaults are such that all the input is kept. So it is possible to set e.g.
7954 just the end values to keep everything before the specified time.
7959 drop everything except the second minute of input
7961 ffmpeg -i INPUT -vf trim=60:120
7965 keep only the first second
7967 ffmpeg -i INPUT -vf trim=duration=1
7975 Sharpen or blur the input video.
7977 It accepts the following parameters:
7980 @item luma_msize_x, lx
7981 Set the luma matrix horizontal size. It must be an odd integer between
7982 3 and 63, default value is 5.
7984 @item luma_msize_y, ly
7985 Set the luma matrix vertical size. It must be an odd integer between 3
7986 and 63, default value is 5.
7988 @item luma_amount, la
7989 Set the luma effect strength. It can be a float number, reasonable
7990 values lay between -1.5 and 1.5.
7992 Negative values will blur the input video, while positive values will
7993 sharpen it, a value of zero will disable the effect.
7995 Default value is 1.0.
7997 @item chroma_msize_x, cx
7998 Set the chroma matrix horizontal size. It must be an odd integer
7999 between 3 and 63, default value is 5.
8001 @item chroma_msize_y, cy
8002 Set the chroma matrix vertical size. It must be an odd integer
8003 between 3 and 63, default value is 5.
8005 @item chroma_amount, ca
8006 Set the chroma effect strength. It can be a float number, reasonable
8007 values lay between -1.5 and 1.5.
8009 Negative values will blur the input video, while positive values will
8010 sharpen it, a value of zero will disable the effect.
8012 Default value is 0.0.
8015 If set to 1, specify using OpenCL capabilities, only available if
8016 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
8020 All parameters are optional and default to the equivalent of the
8021 string '5:5:1.0:5:5:0.0'.
8023 @subsection Examples
8027 Apply strong luma sharpen effect:
8029 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
8033 Apply strong blur of both luma and chroma parameters:
8035 unsharp=7:7:-2:7:7:-2
8039 @anchor{vidstabdetect}
8040 @section vidstabdetect
8042 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
8043 @ref{vidstabtransform} for pass 2.
8045 This filter generates a file with relative translation and rotation
8046 transform information about subsequent frames, which is then used by
8047 the @ref{vidstabtransform} filter.
8049 To enable compilation of this filter you need to configure FFmpeg with
8050 @code{--enable-libvidstab}.
8052 This filter accepts the following options:
8056 Set the path to the file used to write the transforms information.
8057 Default value is @file{transforms.trf}.
8060 Set how shaky the video is and how quick the camera is. It accepts an
8061 integer in the range 1-10, a value of 1 means little shakiness, a
8062 value of 10 means strong shakiness. Default value is 5.
8065 Set the accuracy of the detection process. It must be a value in the
8066 range 1-15. A value of 1 means low accuracy, a value of 15 means high
8067 accuracy. Default value is 15.
8070 Set stepsize of the search process. The region around minimum is
8071 scanned with 1 pixel resolution. Default value is 6.
8074 Set minimum contrast. Below this value a local measurement field is
8075 discarded. Must be a floating point value in the range 0-1. Default
8079 Set reference frame number for tripod mode.
8081 If enabled, the motion of the frames is compared to a reference frame
8082 in the filtered stream, identified by the specified number. The idea
8083 is to compensate all movements in a more-or-less static scene and keep
8084 the camera view absolutely still.
8086 If set to 0, it is disabled. The frames are counted starting from 1.
8089 Show fields and transforms in the resulting frames. It accepts an
8090 integer in the range 0-2. Default value is 0, which disables any
8094 @subsection Examples
8104 Analyze strongly shaky movie and put the results in file
8105 @file{mytransforms.trf}:
8107 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
8111 Visualize the result of internal transformations in the resulting
8114 vidstabdetect=show=1
8118 Analyze a video with medium shakiness using @command{ffmpeg}:
8120 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
8124 @anchor{vidstabtransform}
8125 @section vidstabtransform
8127 Video stabilization/deshaking: pass 2 of 2,
8128 see @ref{vidstabdetect} for pass 1.
8130 Read a file with transform information for each frame and
8131 apply/compensate them. Together with the @ref{vidstabdetect}
8132 filter this can be used to deshake videos. See also
8133 @url{http://public.hronopik.de/vid.stab}. It is important to also use
8134 the unsharp filter, see below.
8136 To enable compilation of this filter you need to configure FFmpeg with
8137 @code{--enable-libvidstab}.
8143 Set path to the file used to read the transforms. Default value is
8144 @file{transforms.trf}).
8147 Set the number of frames (value*2 + 1) used for lowpass filtering the
8148 camera movements. Default value is 10.
8150 For example a number of 10 means that 21 frames are used (10 in the
8151 past and 10 in the future) to smoothen the motion in the video. A
8152 larger values leads to a smoother video, but limits the acceleration
8153 of the camera (pan/tilt movements). 0 is a special case where a
8154 static camera is simulated.
8157 Set the camera path optimization algorithm.
8159 Accepted values are:
8162 gaussian kernel low-pass filter on camera motion (default)
8164 averaging on transformations
8168 Set maximal number of pixels to translate frames. Default value is -1,
8172 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
8173 value is -1, meaning no limit.
8176 Specify how to deal with borders that may be visible due to movement
8179 Available values are:
8182 keep image information from previous frame (default)
8184 fill the border black
8188 Invert transforms if set to 1. Default value is 0.
8191 Consider transforms as relative to previsou frame if set to 1,
8192 absolute if set to 0. Default value is 0.
8195 Set percentage to zoom. A positive value will result in a zoom-in
8196 effect, a negative value in a zoom-out effect. Default value is 0 (no
8200 Set optimal zooming to avoid borders.
8202 Accepted values are:
8207 optimal static zoom value is determined (only very strong movements
8208 will lead to visible borders) (default)
8210 optimal adaptive zoom value is determined (no borders will be
8211 visible), see @option{zoomspeed}
8214 Note that the value given at zoom is added to the one calculated here.
8217 Set percent to zoom maximally each frame (enabled when
8218 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
8222 Specify type of interpolation.
8224 Available values are:
8229 linear only horizontal
8231 linear in both directions (default)
8233 cubic in both directions (slow)
8237 Enable virtual tripod mode if set to 1, which is equivalent to
8238 @code{relative=0:smoothing=0}. Default value is 0.
8240 Use also @code{tripod} option of @ref{vidstabdetect}.
8243 Increase log verbosity if set to 1. Also the detected global motions
8244 are written to the temporary file @file{global_motions.trf}. Default
8248 @subsection Examples
8252 Use @command{ffmpeg} for a typical stabilization with default values:
8254 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
8257 Note the use of the unsharp filter which is always recommended.
8260 Zoom in a bit more and load transform data from a given file:
8262 vidstabtransform=zoom=5:input="mytransforms.trf"
8266 Smoothen the video even more:
8268 vidstabtransform=smoothing=30
8274 Flip the input video vertically.
8276 For example, to vertically flip a video with @command{ffmpeg}:
8278 ffmpeg -i in.avi -vf "vflip" out.avi
8283 Make or reverse a natural vignetting effect.
8285 The filter accepts the following options:
8289 Set lens angle expression as a number of radians.
8291 The value is clipped in the @code{[0,PI/2]} range.
8293 Default value: @code{"PI/5"}
8297 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
8301 Set forward/backward mode.
8303 Available modes are:
8306 The larger the distance from the central point, the darker the image becomes.
8309 The larger the distance from the central point, the brighter the image becomes.
8310 This can be used to reverse a vignette effect, though there is no automatic
8311 detection to extract the lens @option{angle} and other settings (yet). It can
8312 also be used to create a burning effect.
8315 Default value is @samp{forward}.
8318 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
8320 It accepts the following values:
8323 Evaluate expressions only once during the filter initialization.
8326 Evaluate expressions for each incoming frame. This is way slower than the
8327 @samp{init} mode since it requires all the scalers to be re-computed, but it
8328 allows advanced dynamic expressions.
8331 Default value is @samp{init}.
8334 Set dithering to reduce the circular banding effects. Default is @code{1}
8338 Set vignette aspect. This setting allows to adjust the shape of the vignette.
8339 Setting this value to the SAR of the input will make a rectangular vignetting
8340 following the dimensions of the video.
8342 Default is @code{1/1}.
8345 @subsection Expressions
8347 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
8348 following parameters.
8353 input width and height
8356 the number of input frame, starting from 0
8359 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
8360 @var{TB} units, NAN if undefined
8363 frame rate of the input video, NAN if the input frame rate is unknown
8366 the PTS (Presentation TimeStamp) of the filtered video frame,
8367 expressed in seconds, NAN if undefined
8370 time base of the input video
8374 @subsection Examples
8378 Apply simple strong vignetting effect:
8384 Make a flickering vignetting:
8386 vignette='PI/4+random(1)*PI/50':eval=frame
8393 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
8394 Deinterlacing Filter").
8396 Based on the process described by Martin Weston for BBC R&D, and
8397 implemented based on the de-interlace algorithm written by Jim
8398 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
8399 uses filter coefficients calculated by BBC R&D.
8401 There are two sets of filter coefficients, so called "simple":
8402 and "complex". Which set of filter coefficients is used can
8403 be set by passing an optional parameter:
8407 Set the interlacing filter coefficients. Accepts one of the following values:
8411 Simple filter coefficient set.
8413 More-complex filter coefficient set.
8415 Default value is @samp{complex}.
8418 Specify which frames to deinterlace. Accept one of the following values:
8422 Deinterlace all frames,
8424 Only deinterlace frames marked as interlaced.
8427 Default value is @samp{all}.
8433 Deinterlace the input video ("yadif" means "yet another deinterlacing
8436 This filter accepts the following options:
8442 The interlacing mode to adopt, accepts one of the following values:
8446 output 1 frame for each frame
8448 output 1 frame for each field
8449 @item 2, send_frame_nospatial
8450 like @code{send_frame} but skip spatial interlacing check
8451 @item 3, send_field_nospatial
8452 like @code{send_field} but skip spatial interlacing check
8455 Default value is @code{send_frame}.
8458 The picture field parity assumed for the input interlaced video, accepts one of
8459 the following values:
8463 assume top field first
8465 assume bottom field first
8467 enable automatic detection
8470 Default value is @code{auto}.
8471 If interlacing is unknown or decoder does not export this information,
8472 top field first will be assumed.
8475 Specify which frames to deinterlace. Accept one of the following
8480 deinterlace all frames
8482 only deinterlace frames marked as interlaced
8485 Default value is @code{all}.
8488 @c man end VIDEO FILTERS
8490 @chapter Video Sources
8491 @c man begin VIDEO SOURCES
8493 Below is a description of the currently available video sources.
8497 Buffer video frames, and make them available to the filter chain.
8499 This source is mainly intended for a programmatic use, in particular
8500 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
8502 This source accepts the following options:
8507 Specify the size (width and height) of the buffered video frames. For the
8508 syntax of this option, check the "Video size" section in the ffmpeg-utils
8518 A string representing the pixel format of the buffered video frames.
8519 It may be a number corresponding to a pixel format, or a pixel format
8523 Specify the timebase assumed by the timestamps of the buffered frames.
8526 Specify the frame rate expected for the video stream.
8528 @item pixel_aspect, sar
8529 Specify the sample aspect ratio assumed by the video frames.
8532 Specify the optional parameters to be used for the scale filter which
8533 is automatically inserted when an input change is detected in the
8534 input size or format.
8539 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
8542 will instruct the source to accept video frames with size 320x240 and
8543 with format "yuv410p", assuming 1/24 as the timestamps timebase and
8544 square pixels (1:1 sample aspect ratio).
8545 Since the pixel format with name "yuv410p" corresponds to the number 6
8546 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
8547 this example corresponds to:
8549 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
8552 Alternatively, the options can be specified as a flat string, but this
8553 syntax is deprecated:
8555 @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}]
8559 Create a pattern generated by an elementary cellular automaton.
8561 The initial state of the cellular automaton can be defined through the
8562 @option{filename}, and @option{pattern} options. If such options are
8563 not specified an initial state is created randomly.
8565 At each new frame a new row in the video is filled with the result of
8566 the cellular automaton next generation. The behavior when the whole
8567 frame is filled is defined by the @option{scroll} option.
8569 This source accepts the following options:
8573 Read the initial cellular automaton state, i.e. the starting row, from
8575 In the file, each non-whitespace character is considered an alive
8576 cell, a newline will terminate the row, and further characters in the
8577 file will be ignored.
8580 Read the initial cellular automaton state, i.e. the starting row, from
8581 the specified string.
8583 Each non-whitespace character in the string is considered an alive
8584 cell, a newline will terminate the row, and further characters in the
8585 string will be ignored.
8588 Set the video rate, that is the number of frames generated per second.
8591 @item random_fill_ratio, ratio
8592 Set the random fill ratio for the initial cellular automaton row. It
8593 is a floating point number value ranging from 0 to 1, defaults to
8596 This option is ignored when a file or a pattern is specified.
8598 @item random_seed, seed
8599 Set the seed for filling randomly the initial row, must be an integer
8600 included between 0 and UINT32_MAX. If not specified, or if explicitly
8601 set to -1, the filter will try to use a good random seed on a best
8605 Set the cellular automaton rule, it is a number ranging from 0 to 255.
8606 Default value is 110.
8609 Set the size of the output video. For the syntax of this option, check
8610 the "Video size" section in the ffmpeg-utils manual.
8612 If @option{filename} or @option{pattern} is specified, the size is set
8613 by default to the width of the specified initial state row, and the
8614 height is set to @var{width} * PHI.
8616 If @option{size} is set, it must contain the width of the specified
8617 pattern string, and the specified pattern will be centered in the
8620 If a filename or a pattern string is not specified, the size value
8621 defaults to "320x518" (used for a randomly generated initial state).
8624 If set to 1, scroll the output upward when all the rows in the output
8625 have been already filled. If set to 0, the new generated row will be
8626 written over the top row just after the bottom row is filled.
8629 @item start_full, full
8630 If set to 1, completely fill the output with generated rows before
8631 outputting the first frame.
8632 This is the default behavior, for disabling set the value to 0.
8635 If set to 1, stitch the left and right row edges together.
8636 This is the default behavior, for disabling set the value to 0.
8639 @subsection Examples
8643 Read the initial state from @file{pattern}, and specify an output of
8646 cellauto=f=pattern:s=200x400
8650 Generate a random initial row with a width of 200 cells, with a fill
8653 cellauto=ratio=2/3:s=200x200
8657 Create a pattern generated by rule 18 starting by a single alive cell
8658 centered on an initial row with width 100:
8660 cellauto=p=@@:s=100x400:full=0:rule=18
8664 Specify a more elaborated initial pattern:
8666 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
8673 Generate a Mandelbrot set fractal, and progressively zoom towards the
8674 point specified with @var{start_x} and @var{start_y}.
8676 This source accepts the following options:
8681 Set the terminal pts value. Default value is 400.
8684 Set the terminal scale value.
8685 Must be a floating point value. Default value is 0.3.
8688 Set the inner coloring mode, that is the algorithm used to draw the
8689 Mandelbrot fractal internal region.
8691 It shall assume one of the following values:
8696 Show time until convergence.
8698 Set color based on point closest to the origin of the iterations.
8703 Default value is @var{mincol}.
8706 Set the bailout value. Default value is 10.0.
8709 Set the maximum of iterations performed by the rendering
8710 algorithm. Default value is 7189.
8713 Set outer coloring mode.
8714 It shall assume one of following values:
8716 @item iteration_count
8717 Set iteration cound mode.
8718 @item normalized_iteration_count
8719 set normalized iteration count mode.
8721 Default value is @var{normalized_iteration_count}.
8724 Set frame rate, expressed as number of frames per second. Default
8728 Set frame size. For the syntax of this option, check the "Video
8729 size" section in the ffmpeg-utils manual. Default value is "640x480".
8732 Set the initial scale value. Default value is 3.0.
8735 Set the initial x position. Must be a floating point value between
8736 -100 and 100. Default value is -0.743643887037158704752191506114774.
8739 Set the initial y position. Must be a floating point value between
8740 -100 and 100. Default value is -0.131825904205311970493132056385139.
8745 Generate various test patterns, as generated by the MPlayer test filter.
8747 The size of the generated video is fixed, and is 256x256.
8748 This source is useful in particular for testing encoding features.
8750 This source accepts the following options:
8755 Specify the frame rate of the sourced video, as the number of frames
8756 generated per second. It has to be a string in the format
8757 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
8758 number or a valid video frame rate abbreviation. The default value is
8762 Set the video duration of the sourced video. The accepted syntax is:
8767 See also the function @code{av_parse_time()}.
8769 If not specified, or the expressed duration is negative, the video is
8770 supposed to be generated forever.
8774 Set the number or the name of the test to perform. Supported tests are:
8789 Default value is "all", which will cycle through the list of all tests.
8792 For example the following:
8797 will generate a "dc_luma" test pattern.
8801 Provide a frei0r source.
8803 To enable compilation of this filter you need to install the frei0r
8804 header and configure FFmpeg with @code{--enable-frei0r}.
8806 This source accepts the following options:
8811 The size of the video to generate. For the syntax of this option, check the
8812 "Video size" section in the ffmpeg-utils manual.
8815 Framerate of the generated video, may be a string of the form
8816 @var{num}/@var{den} or a frame rate abbreviation.
8819 The name to the frei0r source to load. For more information regarding frei0r and
8820 how to set the parameters read the section @ref{frei0r} in the description of
8824 A '|'-separated list of parameters to pass to the frei0r source.
8828 For example, to generate a frei0r partik0l source with size 200x200
8829 and frame rate 10 which is overlayed on the overlay filter main input:
8831 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
8836 Generate a life pattern.
8838 This source is based on a generalization of John Conway's life game.
8840 The sourced input represents a life grid, each pixel represents a cell
8841 which can be in one of two possible states, alive or dead. Every cell
8842 interacts with its eight neighbours, which are the cells that are
8843 horizontally, vertically, or diagonally adjacent.
8845 At each interaction the grid evolves according to the adopted rule,
8846 which specifies the number of neighbor alive cells which will make a
8847 cell stay alive or born. The @option{rule} option allows to specify
8850 This source accepts the following options:
8854 Set the file from which to read the initial grid state. In the file,
8855 each non-whitespace character is considered an alive cell, and newline
8856 is used to delimit the end of each row.
8858 If this option is not specified, the initial grid is generated
8862 Set the video rate, that is the number of frames generated per second.
8865 @item random_fill_ratio, ratio
8866 Set the random fill ratio for the initial random grid. It is a
8867 floating point number value ranging from 0 to 1, defaults to 1/PHI.
8868 It is ignored when a file is specified.
8870 @item random_seed, seed
8871 Set the seed for filling the initial random grid, must be an integer
8872 included between 0 and UINT32_MAX. If not specified, or if explicitly
8873 set to -1, the filter will try to use a good random seed on a best
8879 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
8880 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
8881 @var{NS} specifies the number of alive neighbor cells which make a
8882 live cell stay alive, and @var{NB} the number of alive neighbor cells
8883 which make a dead cell to become alive (i.e. to "born").
8884 "s" and "b" can be used in place of "S" and "B", respectively.
8886 Alternatively a rule can be specified by an 18-bits integer. The 9
8887 high order bits are used to encode the next cell state if it is alive
8888 for each number of neighbor alive cells, the low order bits specify
8889 the rule for "borning" new cells. Higher order bits encode for an
8890 higher number of neighbor cells.
8891 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
8892 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
8894 Default value is "S23/B3", which is the original Conway's game of life
8895 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
8896 cells, and will born a new cell if there are three alive cells around
8900 Set the size of the output video. For the syntax of this option, check the
8901 "Video size" section in the ffmpeg-utils manual.
8903 If @option{filename} is specified, the size is set by default to the
8904 same size of the input file. If @option{size} is set, it must contain
8905 the size specified in the input file, and the initial grid defined in
8906 that file is centered in the larger resulting area.
8908 If a filename is not specified, the size value defaults to "320x240"
8909 (used for a randomly generated initial grid).
8912 If set to 1, stitch the left and right grid edges together, and the
8913 top and bottom edges also. Defaults to 1.
8916 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
8917 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
8918 value from 0 to 255.
8921 Set the color of living (or new born) cells.
8924 Set the color of dead cells. If @option{mold} is set, this is the first color
8925 used to represent a dead cell.
8928 Set mold color, for definitely dead and moldy cells.
8930 For the syntax of these 3 color options, check the "Color" section in the
8931 ffmpeg-utils manual.
8934 @subsection Examples
8938 Read a grid from @file{pattern}, and center it on a grid of size
8941 life=f=pattern:s=300x300
8945 Generate a random grid of size 200x200, with a fill ratio of 2/3:
8947 life=ratio=2/3:s=200x200
8951 Specify a custom rule for evolving a randomly generated grid:
8957 Full example with slow death effect (mold) using @command{ffplay}:
8959 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
8964 @anchor{haldclutsrc}
8968 @anchor{smptehdbars}
8970 @section color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
8972 The @code{color} source provides an uniformly colored input.
8974 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
8975 @ref{haldclut} filter.
8977 The @code{nullsrc} source returns unprocessed video frames. It is
8978 mainly useful to be employed in analysis / debugging tools, or as the
8979 source for filters which ignore the input data.
8981 The @code{rgbtestsrc} source generates an RGB test pattern useful for
8982 detecting RGB vs BGR issues. You should see a red, green and blue
8983 stripe from top to bottom.
8985 The @code{smptebars} source generates a color bars pattern, based on
8986 the SMPTE Engineering Guideline EG 1-1990.
8988 The @code{smptehdbars} source generates a color bars pattern, based on
8989 the SMPTE RP 219-2002.
8991 The @code{testsrc} source generates a test video pattern, showing a
8992 color pattern, a scrolling gradient and a timestamp. This is mainly
8993 intended for testing purposes.
8995 The sources accept the following options:
9000 Specify the color of the source, only available in the @code{color}
9001 source. For the syntax of this option, check the "Color" section in the
9002 ffmpeg-utils manual.
9005 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
9006 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
9007 pixels to be used as identity matrix for 3D lookup tables. Each component is
9008 coded on a @code{1/(N*N)} scale.
9011 Specify the size of the sourced video. For the syntax of this option, check the
9012 "Video size" section in the ffmpeg-utils manual. The default value is
9015 This option is not available with the @code{haldclutsrc} filter.
9018 Specify the frame rate of the sourced video, as the number of frames
9019 generated per second. It has to be a string in the format
9020 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
9021 number or a valid video frame rate abbreviation. The default value is
9025 Set the sample aspect ratio of the sourced video.
9028 Set the video duration of the sourced video. The accepted syntax is:
9030 [-]HH[:MM[:SS[.m...]]]
9033 See also the function @code{av_parse_time()}.
9035 If not specified, or the expressed duration is negative, the video is
9036 supposed to be generated forever.
9039 Set the number of decimals to show in the timestamp, only available in the
9040 @code{testsrc} source.
9042 The displayed timestamp value will correspond to the original
9043 timestamp value multiplied by the power of 10 of the specified
9044 value. Default value is 0.
9047 For example the following:
9049 testsrc=duration=5.3:size=qcif:rate=10
9052 will generate a video with a duration of 5.3 seconds, with size
9053 176x144 and a frame rate of 10 frames per second.
9055 The following graph description will generate a red source
9056 with an opacity of 0.2, with size "qcif" and a frame rate of 10
9059 color=c=red@@0.2:s=qcif:r=10
9062 If the input content is to be ignored, @code{nullsrc} can be used. The
9063 following command generates noise in the luminance plane by employing
9064 the @code{geq} filter:
9066 nullsrc=s=256x256, geq=random(1)*255:128:128
9069 @subsection Commands
9071 The @code{color} source supports the following commands:
9075 Set the color of the created image. Accepts the same syntax of the
9076 corresponding @option{color} option.
9079 @c man end VIDEO SOURCES
9081 @chapter Video Sinks
9082 @c man begin VIDEO SINKS
9084 Below is a description of the currently available video sinks.
9088 Buffer video frames, and make them available to the end of the filter
9091 This sink is mainly intended for a programmatic use, in particular
9092 through the interface defined in @file{libavfilter/buffersink.h}
9093 or the options system.
9095 It accepts a pointer to an AVBufferSinkContext structure, which
9096 defines the incoming buffers' formats, to be passed as the opaque
9097 parameter to @code{avfilter_init_filter} for initialization.
9101 Null video sink, do absolutely nothing with the input video. It is
9102 mainly useful as a template and to be employed in analysis / debugging
9105 @c man end VIDEO SINKS
9107 @chapter Multimedia Filters
9108 @c man begin MULTIMEDIA FILTERS
9110 Below is a description of the currently available multimedia filters.
9112 @section avectorscope
9114 Convert input audio to a video output, representing the audio vector
9117 The filter is used to measure the difference between channels of stereo
9118 audio stream. A monoaural signal, consisting of identical left and right
9119 signal, results in straight vertical line. Any stereo separation is visible
9120 as a deviation from this line, creating a Lissajous figure.
9121 If the straight (or deviation from it) but horizontal line appears this
9122 indicates that the left and right channels are out of phase.
9124 The filter accepts the following options:
9128 Set the vectorscope mode.
9130 Available values are:
9133 Lissajous rotated by 45 degrees.
9136 Same as above but not rotated.
9139 Default value is @samp{lissajous}.
9142 Set the video size for the output. For the syntax of this option, check the "Video size"
9143 section in the ffmpeg-utils manual. Default value is @code{400x400}.
9146 Set the output frame rate. Default value is @code{25}.
9151 Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}.
9152 Allowed range is @code{[0, 255]}.
9157 Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}.
9158 Allowed range is @code{[0, 255]}.
9161 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
9164 @subsection Examples
9168 Complete example using @command{ffplay}:
9170 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
9171 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
9177 Concatenate audio and video streams, joining them together one after the
9180 The filter works on segments of synchronized video and audio streams. All
9181 segments must have the same number of streams of each type, and that will
9182 also be the number of streams at output.
9184 The filter accepts the following options:
9189 Set the number of segments. Default is 2.
9192 Set the number of output video streams, that is also the number of video
9193 streams in each segment. Default is 1.
9196 Set the number of output audio streams, that is also the number of video
9197 streams in each segment. Default is 0.
9200 Activate unsafe mode: do not fail if segments have a different format.
9204 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
9205 @var{a} audio outputs.
9207 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
9208 segment, in the same order as the outputs, then the inputs for the second
9211 Related streams do not always have exactly the same duration, for various
9212 reasons including codec frame size or sloppy authoring. For that reason,
9213 related synchronized streams (e.g. a video and its audio track) should be
9214 concatenated at once. The concat filter will use the duration of the longest
9215 stream in each segment (except the last one), and if necessary pad shorter
9216 audio streams with silence.
9218 For this filter to work correctly, all segments must start at timestamp 0.
9220 All corresponding streams must have the same parameters in all segments; the
9221 filtering system will automatically select a common pixel format for video
9222 streams, and a common sample format, sample rate and channel layout for
9223 audio streams, but other settings, such as resolution, must be converted
9224 explicitly by the user.
9226 Different frame rates are acceptable but will result in variable frame rate
9227 at output; be sure to configure the output file to handle it.
9229 @subsection Examples
9233 Concatenate an opening, an episode and an ending, all in bilingual version
9234 (video in stream 0, audio in streams 1 and 2):
9236 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
9237 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
9238 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
9239 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
9243 Concatenate two parts, handling audio and video separately, using the
9244 (a)movie sources, and adjusting the resolution:
9246 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
9247 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
9248 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
9250 Note that a desync will happen at the stitch if the audio and video streams
9251 do not have exactly the same duration in the first file.
9257 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
9258 it unchanged. By default, it logs a message at a frequency of 10Hz with the
9259 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
9260 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
9262 The filter also has a video output (see the @var{video} option) with a real
9263 time graph to observe the loudness evolution. The graphic contains the logged
9264 message mentioned above, so it is not printed anymore when this option is set,
9265 unless the verbose logging is set. The main graphing area contains the
9266 short-term loudness (3 seconds of analysis), and the gauge on the right is for
9267 the momentary loudness (400 milliseconds).
9269 More information about the Loudness Recommendation EBU R128 on
9270 @url{http://tech.ebu.ch/loudness}.
9272 The filter accepts the following options:
9277 Activate the video output. The audio stream is passed unchanged whether this
9278 option is set or no. The video stream will be the first output stream if
9279 activated. Default is @code{0}.
9282 Set the video size. This option is for video only. For the syntax of this
9283 option, check the "Video size" section in the ffmpeg-utils manual. Default
9284 and minimum resolution is @code{640x480}.
9287 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
9288 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
9289 other integer value between this range is allowed.
9292 Set metadata injection. If set to @code{1}, the audio input will be segmented
9293 into 100ms output frames, each of them containing various loudness information
9294 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
9296 Default is @code{0}.
9299 Force the frame logging level.
9301 Available values are:
9304 information logging level
9306 verbose logging level
9309 By default, the logging level is set to @var{info}. If the @option{video} or
9310 the @option{metadata} options are set, it switches to @var{verbose}.
9313 @subsection Examples
9317 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
9319 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
9323 Run an analysis with @command{ffmpeg}:
9325 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
9329 @section interleave, ainterleave
9331 Temporally interleave frames from several inputs.
9333 @code{interleave} works with video inputs, @code{ainterleave} with audio.
9335 These filters read frames from several inputs and send the oldest
9336 queued frame to the output.
9338 Input streams must have a well defined, monotonically increasing frame
9341 In order to submit one frame to output, these filters need to enqueue
9342 at least one frame for each input, so they cannot work in case one
9343 input is not yet terminated and will not receive incoming frames.
9345 For example consider the case when one input is a @code{select} filter
9346 which always drop input frames. The @code{interleave} filter will keep
9347 reading from that input, but it will never be able to send new frames
9348 to output until the input will send an end-of-stream signal.
9350 Also, depending on inputs synchronization, the filters will drop
9351 frames in case one input receives more frames than the other ones, and
9352 the queue is already filled.
9354 These filters accept the following options:
9358 Set the number of different inputs, it is 2 by default.
9361 @subsection Examples
9365 Interleave frames belonging to different streams using @command{ffmpeg}:
9367 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
9371 Add flickering blur effect:
9373 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
9377 @section perms, aperms
9379 Set read/write permissions for the output frames.
9381 These filters are mainly aimed at developers to test direct path in the
9382 following filter in the filtergraph.
9384 The filters accept the following options:
9388 Select the permissions mode.
9390 It accepts the following values:
9393 Do nothing. This is the default.
9395 Set all the output frames read-only.
9397 Set all the output frames directly writable.
9399 Make the frame read-only if writable, and writable if read-only.
9401 Set each output frame read-only or writable randomly.
9405 Set the seed for the @var{random} mode, must be an integer included between
9406 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9407 @code{-1}, the filter will try to use a good random seed on a best effort
9411 Note: in case of auto-inserted filter between the permission filter and the
9412 following one, the permission might not be received as expected in that
9413 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
9414 perms/aperms filter can avoid this problem.
9416 @section select, aselect
9418 Select frames to pass in output.
9420 This filter accepts the following options:
9425 Set expression, which is evaluated for each input frame.
9427 If the expression is evaluated to zero, the frame is discarded.
9429 If the evaluation result is negative or NaN, the frame is sent to the
9430 first output; otherwise it is sent to the output with index
9431 @code{ceil(val)-1}, assuming that the input index starts from 0.
9433 For example a value of @code{1.2} corresponds to the output with index
9434 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
9437 Set the number of outputs. The output to which to send the selected
9438 frame is based on the result of the evaluation. Default value is 1.
9441 The expression can contain the following constants:
9445 the sequential number of the filtered frame, starting from 0
9448 the sequential number of the selected frame, starting from 0
9450 @item prev_selected_n
9451 the sequential number of the last selected frame, NAN if undefined
9454 timebase of the input timestamps
9457 the PTS (Presentation TimeStamp) of the filtered video frame,
9458 expressed in @var{TB} units, NAN if undefined
9461 the PTS (Presentation TimeStamp) of the filtered video frame,
9462 expressed in seconds, NAN if undefined
9465 the PTS of the previously filtered video frame, NAN if undefined
9467 @item prev_selected_pts
9468 the PTS of the last previously filtered video frame, NAN if undefined
9470 @item prev_selected_t
9471 the PTS of the last previously selected video frame, NAN if undefined
9474 the PTS of the first video frame in the video, NAN if undefined
9477 the time of the first video frame in the video, NAN if undefined
9479 @item pict_type @emph{(video only)}
9480 the type of the filtered frame, can assume one of the following
9492 @item interlace_type @emph{(video only)}
9493 the frame interlace type, can assume one of the following values:
9496 the frame is progressive (not interlaced)
9498 the frame is top-field-first
9500 the frame is bottom-field-first
9503 @item consumed_sample_n @emph{(audio only)}
9504 the number of selected samples before the current frame
9506 @item samples_n @emph{(audio only)}
9507 the number of samples in the current frame
9509 @item sample_rate @emph{(audio only)}
9510 the input sample rate
9513 1 if the filtered frame is a key-frame, 0 otherwise
9516 the position in the file of the filtered frame, -1 if the information
9517 is not available (e.g. for synthetic video)
9519 @item scene @emph{(video only)}
9520 value between 0 and 1 to indicate a new scene; a low value reflects a low
9521 probability for the current frame to introduce a new scene, while a higher
9522 value means the current frame is more likely to be one (see the example below)
9526 The default value of the select expression is "1".
9528 @subsection Examples
9532 Select all frames in input:
9537 The example above is the same as:
9549 Select only I-frames:
9551 select='eq(pict_type\,I)'
9555 Select one frame every 100:
9557 select='not(mod(n\,100))'
9561 Select only frames contained in the 10-20 time interval:
9563 select=between(t\,10\,20)
9567 Select only I frames contained in the 10-20 time interval:
9569 select=between(t\,10\,20)*eq(pict_type\,I)
9573 Select frames with a minimum distance of 10 seconds:
9575 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
9579 Use aselect to select only audio frames with samples number > 100:
9581 aselect='gt(samples_n\,100)'
9585 Create a mosaic of the first scenes:
9587 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
9590 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
9594 Send even and odd frames to separate outputs, and compose them:
9596 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
9600 @section sendcmd, asendcmd
9602 Send commands to filters in the filtergraph.
9604 These filters read commands to be sent to other filters in the
9607 @code{sendcmd} must be inserted between two video filters,
9608 @code{asendcmd} must be inserted between two audio filters, but apart
9609 from that they act the same way.
9611 The specification of commands can be provided in the filter arguments
9612 with the @var{commands} option, or in a file specified by the
9613 @var{filename} option.
9615 These filters accept the following options:
9618 Set the commands to be read and sent to the other filters.
9620 Set the filename of the commands to be read and sent to the other
9624 @subsection Commands syntax
9626 A commands description consists of a sequence of interval
9627 specifications, comprising a list of commands to be executed when a
9628 particular event related to that interval occurs. The occurring event
9629 is typically the current frame time entering or leaving a given time
9632 An interval is specified by the following syntax:
9634 @var{START}[-@var{END}] @var{COMMANDS};
9637 The time interval is specified by the @var{START} and @var{END} times.
9638 @var{END} is optional and defaults to the maximum time.
9640 The current frame time is considered within the specified interval if
9641 it is included in the interval [@var{START}, @var{END}), that is when
9642 the time is greater or equal to @var{START} and is lesser than
9645 @var{COMMANDS} consists of a sequence of one or more command
9646 specifications, separated by ",", relating to that interval. The
9647 syntax of a command specification is given by:
9649 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
9652 @var{FLAGS} is optional and specifies the type of events relating to
9653 the time interval which enable sending the specified command, and must
9654 be a non-null sequence of identifier flags separated by "+" or "|" and
9655 enclosed between "[" and "]".
9657 The following flags are recognized:
9660 The command is sent when the current frame timestamp enters the
9661 specified interval. In other words, the command is sent when the
9662 previous frame timestamp was not in the given interval, and the
9666 The command is sent when the current frame timestamp leaves the
9667 specified interval. In other words, the command is sent when the
9668 previous frame timestamp was in the given interval, and the
9672 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
9675 @var{TARGET} specifies the target of the command, usually the name of
9676 the filter class or a specific filter instance name.
9678 @var{COMMAND} specifies the name of the command for the target filter.
9680 @var{ARG} is optional and specifies the optional list of argument for
9681 the given @var{COMMAND}.
9683 Between one interval specification and another, whitespaces, or
9684 sequences of characters starting with @code{#} until the end of line,
9685 are ignored and can be used to annotate comments.
9687 A simplified BNF description of the commands specification syntax
9690 @var{COMMAND_FLAG} ::= "enter" | "leave"
9691 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
9692 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
9693 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
9694 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
9695 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
9698 @subsection Examples
9702 Specify audio tempo change at second 4:
9704 asendcmd=c='4.0 atempo tempo 1.5',atempo
9708 Specify a list of drawtext and hue commands in a file.
9710 # show text in the interval 5-10
9711 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
9712 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
9714 # desaturate the image in the interval 15-20
9715 15.0-20.0 [enter] hue s 0,
9716 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
9718 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
9720 # apply an exponential saturation fade-out effect, starting from time 25
9721 25 [enter] hue s exp(25-t)
9724 A filtergraph allowing to read and process the above command list
9725 stored in a file @file{test.cmd}, can be specified with:
9727 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
9732 @section setpts, asetpts
9734 Change the PTS (presentation timestamp) of the input frames.
9736 @code{setpts} works on video frames, @code{asetpts} on audio frames.
9738 This filter accepts the following options:
9743 The expression which is evaluated for each frame to construct its timestamp.
9747 The expression is evaluated through the eval API and can contain the following
9752 frame rate, only defined for constant frame-rate video
9755 the presentation timestamp in input
9758 the count of the input frame for video or the number of consumed samples,
9759 not including the current frame for audio, starting from 0.
9761 @item NB_CONSUMED_SAMPLES
9762 the number of consumed samples, not including the current frame (only
9766 the number of samples in the current frame (only audio)
9768 @item SAMPLE_RATE, SR
9772 the PTS of the first frame
9775 the time in seconds of the first frame
9778 tell if the current frame is interlaced
9781 the time in seconds of the current frame
9784 original position in the file of the frame, or undefined if undefined
9785 for the current frame
9791 previous input time in seconds
9797 previous output time in seconds
9800 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
9804 wallclock (RTC) time at the start of the movie in microseconds
9807 timebase of the input timestamps
9811 @subsection Examples
9815 Start counting PTS from zero
9821 Apply fast motion effect:
9827 Apply slow motion effect:
9833 Set fixed rate of 25 frames per second:
9839 Set fixed rate 25 fps with some jitter:
9841 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
9845 Apply an offset of 10 seconds to the input PTS:
9851 Generate timestamps from a "live source" and rebase onto the current timebase:
9853 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
9857 Generate timestamps by counting samples:
9864 @section settb, asettb
9866 Set the timebase to use for the output frames timestamps.
9867 It is mainly useful for testing timebase configuration.
9869 This filter accepts the following options:
9874 The expression which is evaluated into the output timebase.
9878 The value for @option{tb} is an arithmetic expression representing a
9879 rational. The expression can contain the constants "AVTB" (the default
9880 timebase), "intb" (the input timebase) and "sr" (the sample rate,
9881 audio only). Default value is "intb".
9883 @subsection Examples
9887 Set the timebase to 1/25:
9893 Set the timebase to 1/10:
9899 Set the timebase to 1001/1000:
9905 Set the timebase to 2*intb:
9911 Set the default timebase value:
9917 @section showspectrum
9919 Convert input audio to a video output, representing the audio frequency
9922 The filter accepts the following options:
9926 Specify the video size for the output. For the syntax of this option, check
9927 the "Video size" section in the ffmpeg-utils manual. Default value is
9931 Specify if the spectrum should slide along the window. Default value is
9935 Specify display mode.
9937 It accepts the following values:
9940 all channels are displayed in the same row
9942 all channels are displayed in separate rows
9945 Default value is @samp{combined}.
9948 Specify display color mode.
9950 It accepts the following values:
9953 each channel is displayed in a separate color
9955 each channel is is displayed using the same color scheme
9958 Default value is @samp{channel}.
9961 Specify scale used for calculating intensity color values.
9963 It accepts the following values:
9968 square root, default
9975 Default value is @samp{sqrt}.
9978 Set saturation modifier for displayed colors. Negative values provide
9979 alternative color scheme. @code{0} is no saturation at all.
9980 Saturation must be in [-10.0, 10.0] range.
9981 Default value is @code{1}.
9984 Set window function.
9986 It accepts the following values:
9989 No samples pre-processing (do not expect this to be faster)
9998 Default value is @code{hann}.
10001 The usage is very similar to the showwaves filter; see the examples in that
10004 @subsection Examples
10008 Large window with logarithmic color scaling:
10010 showspectrum=s=1280x480:scale=log
10014 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
10016 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
10017 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
10023 Convert input audio to a video output, representing the samples waves.
10025 The filter accepts the following options:
10029 Specify the video size for the output. For the syntax of this option, check
10030 the "Video size" section in the ffmpeg-utils manual. Default value
10036 Available values are:
10039 Draw a point for each sample.
10042 Draw a vertical line for each sample.
10045 Default value is @code{point}.
10048 Set the number of samples which are printed on the same column. A
10049 larger value will decrease the frame rate. Must be a positive
10050 integer. This option can be set only if the value for @var{rate}
10051 is not explicitly specified.
10054 Set the (approximate) output frame rate. This is done by setting the
10055 option @var{n}. Default value is "25".
10059 @subsection Examples
10063 Output the input file audio and the corresponding video representation
10066 amovie=a.mp3,asplit[out0],showwaves[out1]
10070 Create a synthetic signal and show it with showwaves, forcing a
10071 frame rate of 30 frames per second:
10073 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
10077 @section split, asplit
10079 Split input into several identical outputs.
10081 @code{asplit} works with audio input, @code{split} with video.
10083 The filter accepts a single parameter which specifies the number of outputs. If
10084 unspecified, it defaults to 2.
10086 @subsection Examples
10090 Create two separate outputs from the same input:
10092 [in] split [out0][out1]
10096 To create 3 or more outputs, you need to specify the number of
10099 [in] asplit=3 [out0][out1][out2]
10103 Create two separate outputs from the same input, one cropped and
10106 [in] split [splitout1][splitout2];
10107 [splitout1] crop=100:100:0:0 [cropout];
10108 [splitout2] pad=200:200:100:100 [padout];
10112 Create 5 copies of the input audio with @command{ffmpeg}:
10114 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
10120 Receive commands sent through a libzmq client, and forward them to
10121 filters in the filtergraph.
10123 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
10124 must be inserted between two video filters, @code{azmq} between two
10127 To enable these filters you need to install the libzmq library and
10128 headers and configure FFmpeg with @code{--enable-libzmq}.
10130 For more information about libzmq see:
10131 @url{http://www.zeromq.org/}
10133 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
10134 receives messages sent through a network interface defined by the
10135 @option{bind_address} option.
10137 The received message must be in the form:
10139 @var{TARGET} @var{COMMAND} [@var{ARG}]
10142 @var{TARGET} specifies the target of the command, usually the name of
10143 the filter class or a specific filter instance name.
10145 @var{COMMAND} specifies the name of the command for the target filter.
10147 @var{ARG} is optional and specifies the optional argument list for the
10148 given @var{COMMAND}.
10150 Upon reception, the message is processed and the corresponding command
10151 is injected into the filtergraph. Depending on the result, the filter
10152 will send a reply to the client, adopting the format:
10154 @var{ERROR_CODE} @var{ERROR_REASON}
10158 @var{MESSAGE} is optional.
10160 @subsection Examples
10162 Look at @file{tools/zmqsend} for an example of a zmq client which can
10163 be used to send commands processed by these filters.
10165 Consider the following filtergraph generated by @command{ffplay}
10167 ffplay -dumpgraph 1 -f lavfi "
10168 color=s=100x100:c=red [l];
10169 color=s=100x100:c=blue [r];
10170 nullsrc=s=200x100, zmq [bg];
10171 [bg][l] overlay [bg+l];
10172 [bg+l][r] overlay=x=100 "
10175 To change the color of the left side of the video, the following
10176 command can be used:
10178 echo Parsed_color_0 c yellow | tools/zmqsend
10181 To change the right side:
10183 echo Parsed_color_1 c pink | tools/zmqsend
10186 @c man end MULTIMEDIA FILTERS
10188 @chapter Multimedia Sources
10189 @c man begin MULTIMEDIA SOURCES
10191 Below is a description of the currently available multimedia sources.
10195 This is the same as @ref{movie} source, except it selects an audio
10201 Read audio and/or video stream(s) from a movie container.
10203 This filter accepts the following options:
10207 The name of the resource to read (not necessarily a file but also a device or a
10208 stream accessed through some protocol).
10210 @item format_name, f
10211 Specifies the format assumed for the movie to read, and can be either
10212 the name of a container or an input device. If not specified the
10213 format is guessed from @var{movie_name} or by probing.
10215 @item seek_point, sp
10216 Specifies the seek point in seconds, the frames will be output
10217 starting from this seek point, the parameter is evaluated with
10218 @code{av_strtod} so the numerical value may be suffixed by an IS
10219 postfix. Default value is "0".
10222 Specifies the streams to read. Several streams can be specified,
10223 separated by "+". The source will then have as many outputs, in the
10224 same order. The syntax is explained in the ``Stream specifiers''
10225 section in the ffmpeg manual. Two special names, "dv" and "da" specify
10226 respectively the default (best suited) video and audio stream. Default
10227 is "dv", or "da" if the filter is called as "amovie".
10229 @item stream_index, si
10230 Specifies the index of the video stream to read. If the value is -1,
10231 the best suited video stream will be automatically selected. Default
10232 value is "-1". Deprecated. If the filter is called "amovie", it will select
10233 audio instead of video.
10236 Specifies how many times to read the stream in sequence.
10237 If the value is less than 1, the stream will be read again and again.
10238 Default value is "1".
10240 Note that when the movie is looped the source timestamps are not
10241 changed, so it will generate non monotonically increasing timestamps.
10244 This filter allows to overlay a second video on top of main input of
10245 a filtergraph as shown in this graph:
10247 input -----------> deltapts0 --> overlay --> output
10250 movie --> scale--> deltapts1 -------+
10253 @subsection Examples
10257 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
10258 on top of the input labelled as "in":
10260 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
10261 [in] setpts=PTS-STARTPTS [main];
10262 [main][over] overlay=16:16 [out]
10266 Read from a video4linux2 device, and overlay it on top of the input
10269 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
10270 [in] setpts=PTS-STARTPTS [main];
10271 [main][over] overlay=16:16 [out]
10275 Read the first video stream and the audio stream with id 0x81 from
10276 dvd.vob; the video is connected to the pad named "video" and the audio is
10277 connected to the pad named "audio":
10279 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
10283 @c man end MULTIMEDIA SOURCES