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 Filtergraph description composition entails several levels of
221 escaping. See @ref{quoting_and_escaping,,the "Quoting and escaping"
222 section in the ffmpeg-utils(1) manual,ffmpeg-utils} for more
223 information about the employed escaping procedure.
225 A first level escaping affects the content of each filter option
226 value, which may contain the special character @code{:} used to
227 separate values, or one of the escaping characters @code{\'}.
229 A second level escaping affects the whole filter description, which
230 may contain the escaping characters @code{\'} or the special
231 characters @code{[],;} used by the filtergraph description.
233 Finally, when you specify a filtergraph on a shell commandline, you
234 need to perform a third level escaping for the shell special
235 characters contained within it.
237 For example, consider the following string to be embedded in
238 the @ref{drawtext} filter description @option{text} value:
240 this is a 'string': may contain one, or more, special characters
243 This string contains the @code{'} special escaping character, and the
244 @code{:} special character, so it needs to be escaped in this way:
246 text=this is a \'string\'\: may contain one, or more, special characters
249 A second level of escaping is required when embedding the filter
250 description in a filtergraph description, in order to escape all the
251 filtergraph special characters. Thus the example above becomes:
253 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
255 (note that in addition to the @code{\'} escaping special characters,
256 also @code{,} needs to be escaped).
258 Finally an additional level of escaping is needed when writing the
259 filtergraph description in a shell command, which depends on the
260 escaping rules of the adopted shell. For example, assuming that
261 @code{\} is special and needs to be escaped with another @code{\}, the
262 previous string will finally result in:
264 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
267 @chapter Timeline editing
269 Some filters support a generic @option{enable} option. For the filters
270 supporting timeline editing, this option can be set to an expression which is
271 evaluated before sending a frame to the filter. If the evaluation is non-zero,
272 the filter will be enabled, otherwise the frame will be sent unchanged to the
273 next filter in the filtergraph.
275 The expression accepts the following values:
278 timestamp expressed in seconds, NAN if the input timestamp is unknown
281 sequential number of the input frame, starting from 0
284 the position in the file of the input frame, NAN if unknown
287 Additionally, these filters support an @option{enable} command that can be used
288 to re-define the expression.
290 Like any other filtering option, the @option{enable} option follows the same
293 For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3
294 minutes, and a @ref{curves} filter starting at 3 seconds:
296 smartblur = enable='between(t,10,3*60)',
297 curves = enable='gte(t,3)' : preset=cross_process
300 @c man end FILTERGRAPH DESCRIPTION
302 @chapter Audio Filters
303 @c man begin AUDIO FILTERS
305 When you configure your FFmpeg build, you can disable any of the
306 existing filters using @code{--disable-filters}.
307 The configure output will show the audio filters included in your
310 Below is a description of the currently available audio filters.
314 Convert the input audio format to the specified formats.
316 @emph{This filter is deprecated. Use @ref{aformat} instead.}
318 The filter accepts a string of the form:
319 "@var{sample_format}:@var{channel_layout}".
321 @var{sample_format} specifies the sample format, and can be a string or the
322 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
323 suffix for a planar sample format.
325 @var{channel_layout} specifies the channel layout, and can be a string
326 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
328 The special parameter "auto", signifies that the filter will
329 automatically select the output format depending on the output filter.
335 Convert input to float, planar, stereo:
341 Convert input to unsigned 8-bit, automatically select out channel layout:
349 Delay one or more audio channels.
351 Samples in delayed channel are filled with silence.
353 The filter accepts the following option:
357 Set list of delays in milliseconds for each channel separated by '|'.
358 At least one delay greater than 0 should be provided.
359 Unused delays will be silently ignored. If number of given delays is
360 smaller than number of channels all remaining channels will not be delayed.
367 Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
368 the second channel (and any other channels that may be present) unchanged.
376 Apply echoing to the input audio.
378 Echoes are reflected sound and can occur naturally amongst mountains
379 (and sometimes large buildings) when talking or shouting; digital echo
380 effects emulate this behaviour and are often used to help fill out the
381 sound of a single instrument or vocal. The time difference between the
382 original signal and the reflection is the @code{delay}, and the
383 loudness of the reflected signal is the @code{decay}.
384 Multiple echoes can have different delays and decays.
386 A description of the accepted parameters follows.
390 Set input gain of reflected signal. Default is @code{0.6}.
393 Set output gain of reflected signal. Default is @code{0.3}.
396 Set list of time intervals in milliseconds between original signal and reflections
397 separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}.
398 Default is @code{1000}.
401 Set list of loudnesses of reflected signals separated by '|'.
402 Allowed range for each @code{decay} is @code{(0 - 1.0]}.
403 Default is @code{0.5}.
410 Make it sound as if there are twice as many instruments as are actually playing:
412 aecho=0.8:0.88:60:0.4
416 If delay is very short, then it sound like a (metallic) robot playing music:
422 A longer delay will sound like an open air concert in the mountains:
424 aecho=0.8:0.9:1000:0.3
428 Same as above but with one more mountain:
430 aecho=0.8:0.9:1000|1800:0.3|0.25
436 Modify an audio signal according to the specified expressions.
438 This filter accepts one or more expressions (one for each channel),
439 which are evaluated and used to modify a corresponding audio signal.
441 This filter accepts the following options:
445 Set the '|'-separated expressions list for each separate channel. If
446 the number of input channels is greater than the number of
447 expressions, the last specified expression is used for the remaining
450 @item channel_layout, c
451 Set output channel layout. If not specified, the channel layout is
452 specified by the number of expressions. If set to @samp{same}, it will
453 use by default the same input channel layout.
456 Each expression in @var{exprs} can contain the following constants and functions:
460 channel number of the current expression
463 number of the evaluated sample, starting from 0
469 time of the evaluated sample expressed in seconds
472 @item nb_out_channels
473 input and output number of channels
476 the value of input channel with number @var{CH}
479 Note: this filter is slow. For faster processing you should use a
488 aeval=val(ch)/2:c=same
492 Invert phase of the second channel:
500 Apply fade-in/out effect to input audio.
502 A description of the accepted parameters follows.
506 Specify the effect type, can be either @code{in} for fade-in, or
507 @code{out} for a fade-out effect. Default is @code{in}.
509 @item start_sample, ss
510 Specify the number of the start sample for starting to apply the fade
511 effect. Default is 0.
514 Specify the number of samples for which the fade effect has to last. At
515 the end of the fade-in effect the output audio will have the same
516 volume as the input audio, at the end of the fade-out transition
517 the output audio will be silence. Default is 44100.
520 Specify time for starting to apply the fade effect. Default is 0.
521 The accepted syntax is:
523 [-]HH[:MM[:SS[.m...]]]
526 See also the function @code{av_parse_time()}.
527 If set this option is used instead of @var{start_sample} one.
530 Specify the duration for which the fade effect has to last. Default is 0.
531 The accepted syntax is:
533 [-]HH[:MM[:SS[.m...]]]
536 See also the function @code{av_parse_time()}.
537 At the end of the fade-in effect the output audio will have the same
538 volume as the input audio, at the end of the fade-out transition
539 the output audio will be silence.
540 If set this option is used instead of @var{nb_samples} one.
543 Set curve for fade transition.
545 It accepts the following values:
548 select triangular, linear slope (default)
550 select quarter of sine wave
552 select half of sine wave
554 select exponential sine wave
558 select inverted parabola
574 Fade in first 15 seconds of audio:
580 Fade out last 25 seconds of a 900 seconds audio:
582 afade=t=out:st=875:d=25
589 Set output format constraints for the input audio. The framework will
590 negotiate the most appropriate format to minimize conversions.
592 The filter accepts the following named parameters:
596 A '|'-separated list of requested sample formats.
599 A '|'-separated list of requested sample rates.
601 @item channel_layouts
602 A '|'-separated list of requested channel layouts.
604 See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils}
605 for the required syntax.
608 If a parameter is omitted, all values are allowed.
610 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
612 aformat=sample_fmts=u8|s16:channel_layouts=stereo
617 Apply a two-pole all-pass filter with central frequency (in Hz)
618 @var{frequency}, and filter-width @var{width}.
619 An all-pass filter changes the audio's frequency to phase relationship
620 without changing its frequency to amplitude relationship.
622 The filter accepts the following options:
629 Set method to specify band-width of filter.
642 Specify the band-width of a filter in width_type units.
647 Merge two or more audio streams into a single multi-channel stream.
649 The filter accepts the following options:
654 Set the number of inputs. Default is 2.
658 If the channel layouts of the inputs are disjoint, and therefore compatible,
659 the channel layout of the output will be set accordingly and the channels
660 will be reordered as necessary. If the channel layouts of the inputs are not
661 disjoint, the output will have all the channels of the first input then all
662 the channels of the second input, in that order, and the channel layout of
663 the output will be the default value corresponding to the total number of
666 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
667 is FC+BL+BR, then the output will be in 5.1, with the channels in the
668 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
669 first input, b1 is the first channel of the second input).
671 On the other hand, if both input are in stereo, the output channels will be
672 in the default order: a1, a2, b1, b2, and the channel layout will be
673 arbitrarily set to 4.0, which may or may not be the expected value.
675 All inputs must have the same sample rate, and format.
677 If inputs do not have the same duration, the output will stop with the
684 Merge two mono files into a stereo stream:
686 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
690 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
692 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
698 Mixes multiple audio inputs into a single output.
702 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
704 will mix 3 input audio streams to a single output with the same duration as the
705 first input and a dropout transition time of 3 seconds.
707 The filter accepts the following named parameters:
711 Number of inputs. If unspecified, it defaults to 2.
714 How to determine the end-of-stream.
718 Duration of longest input. (default)
721 Duration of shortest input.
724 Duration of first input.
728 @item dropout_transition
729 Transition time, in seconds, for volume renormalization when an input
730 stream ends. The default value is 2 seconds.
736 Pass the audio source unchanged to the output.
740 Pad the end of a audio stream with silence, this can be used together with
741 -shortest to extend audio streams to the same length as the video stream.
744 Add a phasing effect to the input audio.
746 A phaser filter creates series of peaks and troughs in the frequency spectrum.
747 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
749 A description of the accepted parameters follows.
753 Set input gain. Default is 0.4.
756 Set output gain. Default is 0.74
759 Set delay in milliseconds. Default is 3.0.
762 Set decay. Default is 0.4.
765 Set modulation speed in Hz. Default is 0.5.
768 Set modulation type. Default is triangular.
770 It accepts the following values:
780 Resample the input audio to the specified parameters, using the
781 libswresample library. If none are specified then the filter will
782 automatically convert between its input and output.
784 This filter is also able to stretch/squeeze the audio data to make it match
785 the timestamps or to inject silence / cut out audio to make it match the
786 timestamps, do a combination of both or do neither.
788 The filter accepts the syntax
789 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
790 expresses a sample rate and @var{resampler_options} is a list of
791 @var{key}=@var{value} pairs, separated by ":". See the
792 ffmpeg-resampler manual for the complete list of supported options.
798 Resample the input audio to 44100Hz:
804 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
805 samples per second compensation:
811 @section asetnsamples
813 Set the number of samples per each output audio frame.
815 The last output packet may contain a different number of samples, as
816 the filter will flush all the remaining samples when the input audio
819 The filter accepts the following options:
823 @item nb_out_samples, n
824 Set the number of frames per each output audio frame. The number is
825 intended as the number of samples @emph{per each channel}.
826 Default value is 1024.
829 If set to 1, the filter will pad the last audio frame with zeroes, so
830 that the last frame will contain the same number of samples as the
831 previous ones. Default value is 1.
834 For example, to set the number of per-frame samples to 1234 and
835 disable padding for the last frame, use:
837 asetnsamples=n=1234:p=0
842 Set the sample rate without altering the PCM data.
843 This will result in a change of speed and pitch.
845 The filter accepts the following options:
849 Set the output sample rate. Default is 44100 Hz.
854 Show a line containing various information for each input audio frame.
855 The input audio is not modified.
857 The shown line contains a sequence of key/value pairs of the form
858 @var{key}:@var{value}.
860 A description of each shown parameter follows:
864 sequential number of the input frame, starting from 0
867 Presentation timestamp of the input frame, in time base units; the time base
868 depends on the filter input pad, and is usually 1/@var{sample_rate}.
871 presentation timestamp of the input frame in seconds
874 position of the frame in the input stream, -1 if this information in
875 unavailable and/or meaningless (for example in case of synthetic audio)
884 sample rate for the audio frame
887 number of samples (per channel) in the frame
890 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
891 the data is treated as if all the planes were concatenated.
893 @item plane_checksums
894 A list of Adler-32 checksums for each data plane.
899 Display time domain statistical information about the audio channels.
900 Statistics are calculated and displayed for each audio channel and,
901 where applicable, an overall figure is also given.
903 The filter accepts the following option:
906 Short window length in seconds, used for peak and trough RMS measurement.
907 Default is @code{0.05} (50 miliseconds). Allowed range is @code{[0.1 - 10]}.
910 A description of each shown parameter follows:
914 Mean amplitude displacement from zero.
917 Minimal sample level.
920 Maximal sample level.
924 Standard peak and RMS level measured in dBFS.
928 Peak and trough values for RMS level measured over a short window.
931 Standard ratio of peak to RMS level (note: not in dB).
934 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
935 (i.e. either @var{Min level} or @var{Max level}).
938 Number of occasions (not the number of samples) that the signal attained either
939 @var{Min level} or @var{Max level}.
944 Forward two audio streams and control the order the buffers are forwarded.
946 The filter accepts the following options:
950 Set the expression deciding which stream should be
951 forwarded next: if the result is negative, the first stream is forwarded; if
952 the result is positive or zero, the second stream is forwarded. It can use
953 the following variables:
957 number of buffers forwarded so far on each stream
959 number of samples forwarded so far on each stream
961 current timestamp of each stream
964 The default value is @code{t1-t2}, which means to always forward the stream
965 that has a smaller timestamp.
970 Stress-test @code{amerge} by randomly sending buffers on the wrong
971 input, while avoiding too much of a desynchronization:
973 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
974 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
980 Synchronize audio data with timestamps by squeezing/stretching it and/or
981 dropping samples/adding silence when needed.
983 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
985 The filter accepts the following named parameters:
989 Enable stretching/squeezing the data to make it match the timestamps. Disabled
990 by default. When disabled, time gaps are covered with silence.
993 Minimum difference between timestamps and audio data (in seconds) to trigger
994 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
995 this filter, try setting this parameter to 0.
998 Maximum compensation in samples per second. Relevant only with compensate=1.
1002 Assume the first pts should be this value. The time base is 1 / sample rate.
1003 This allows for padding/trimming at the start of stream. By default, no
1004 assumption is made about the first frame's expected pts, so no padding or
1005 trimming is done. For example, this could be set to 0 to pad the beginning with
1006 silence if an audio stream starts after the video stream or to trim any samples
1007 with a negative pts due to encoder delay.
1015 The filter accepts exactly one parameter, the audio tempo. If not
1016 specified then the filter will assume nominal 1.0 tempo. Tempo must
1017 be in the [0.5, 2.0] range.
1019 @subsection Examples
1023 Slow down audio to 80% tempo:
1029 To speed up audio to 125% tempo:
1037 Trim the input so that the output contains one continuous subpart of the input.
1039 This filter accepts the following options:
1042 Specify time of the start of the kept section, i.e. the audio sample
1043 with the timestamp @var{start} will be the first sample in the output.
1046 Specify time of the first audio sample that will be dropped, i.e. the
1047 audio sample immediately preceding the one with the timestamp @var{end} will be
1048 the last sample in the output.
1051 Same as @var{start}, except this option sets the start timestamp in samples
1055 Same as @var{end}, except this option sets the end timestamp in samples instead
1059 Specify maximum duration of the output.
1062 Number of the first sample that should be passed to output.
1065 Number of the first sample that should be dropped.
1068 @option{start}, @option{end}, @option{duration} are expressed as time
1069 duration specifications, check the "Time duration" section in the
1070 ffmpeg-utils manual.
1072 Note that the first two sets of the start/end options and the @option{duration}
1073 option look at the frame timestamp, while the _sample options simply count the
1074 samples that pass through the filter. So start/end_pts and start/end_sample will
1075 give different results when the timestamps are wrong, inexact or do not start at
1076 zero. Also note that this filter does not modify the timestamps. If you wish
1077 that the output timestamps start at zero, insert the asetpts filter after the
1080 If multiple start or end options are set, this filter tries to be greedy and
1081 keep all samples that match at least one of the specified constraints. To keep
1082 only the part that matches all the constraints at once, chain multiple atrim
1085 The defaults are such that all the input is kept. So it is possible to set e.g.
1086 just the end values to keep everything before the specified time.
1091 drop everything except the second minute of input
1093 ffmpeg -i INPUT -af atrim=60:120
1097 keep only the first 1000 samples
1099 ffmpeg -i INPUT -af atrim=end_sample=1000
1106 Apply a two-pole Butterworth band-pass filter with central
1107 frequency @var{frequency}, and (3dB-point) band-width width.
1108 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1109 instead of the default: constant 0dB peak gain.
1110 The filter roll off at 6dB per octave (20dB per decade).
1112 The filter accepts the following options:
1116 Set the filter's central frequency. Default is @code{3000}.
1119 Constant skirt gain if set to 1. Defaults to 0.
1122 Set method to specify band-width of filter.
1135 Specify the band-width of a filter in width_type units.
1140 Apply a two-pole Butterworth band-reject filter with central
1141 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1142 The filter roll off at 6dB per octave (20dB per decade).
1144 The filter accepts the following options:
1148 Set the filter's central frequency. Default is @code{3000}.
1151 Set method to specify band-width of filter.
1164 Specify the band-width of a filter in width_type units.
1169 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1170 shelving filter with a response similar to that of a standard
1171 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1173 The filter accepts the following options:
1177 Give the gain at 0 Hz. Its useful range is about -20
1178 (for a large cut) to +20 (for a large boost).
1179 Beware of clipping when using a positive gain.
1182 Set the filter's central frequency and so can be used
1183 to extend or reduce the frequency range to be boosted or cut.
1184 The default value is @code{100} Hz.
1187 Set method to specify band-width of filter.
1200 Determine how steep is the filter's shelf transition.
1205 Apply a biquad IIR filter with the given coefficients.
1206 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1207 are the numerator and denominator coefficients respectively.
1211 Remap input channels to new locations.
1213 This filter accepts the following named parameters:
1215 @item channel_layout
1216 Channel layout of the output stream.
1219 Map channels from input to output. The argument is a '|'-separated list of
1220 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1221 @var{in_channel} form. @var{in_channel} can be either the name of the input
1222 channel (e.g. FL for front left) or its index in the input channel layout.
1223 @var{out_channel} is the name of the output channel or its index in the output
1224 channel layout. If @var{out_channel} is not given then it is implicitly an
1225 index, starting with zero and increasing by one for each mapping.
1228 If no mapping is present, the filter will implicitly map input channels to
1229 output channels preserving index.
1231 For example, assuming a 5.1+downmix input MOV file
1233 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1235 will create an output WAV file tagged as stereo from the downmix channels of
1238 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1240 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1243 @section channelsplit
1245 Split each channel in input audio stream into a separate output stream.
1247 This filter accepts the following named parameters:
1249 @item channel_layout
1250 Channel layout of the input stream. Default is "stereo".
1253 For example, assuming a stereo input MP3 file
1255 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1257 will create an output Matroska file with two audio streams, one containing only
1258 the left channel and the other the right channel.
1260 To split a 5.1 WAV file into per-channel files
1262 ffmpeg -i in.wav -filter_complex
1263 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1264 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1265 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1271 Compress or expand audio dynamic range.
1273 A description of the accepted options follows.
1278 Set list of times in seconds for each channel over which the instantaneous
1279 level of the input signal is averaged to determine its volume.
1280 @option{attacks} refers to increase of volume and @option{decays} refers
1281 to decrease of volume.
1282 For most situations, the attack time (response to the audio getting louder)
1283 should be shorter than the decay time because the human ear is more sensitive
1284 to sudden loud audio than sudden soft audio.
1285 Typical value for attack is @code{0.3} seconds and for decay @code{0.8}
1289 Set list of points for transfer function, specified in dB relative to maximum
1290 possible signal amplitude.
1291 Each key points list need to be defined using the following syntax:
1292 @code{x0/y0 x1/y1 x2/y2 ...}.
1294 The input values must be in strictly increasing order but the transfer
1295 function does not have to be monotonically rising.
1296 The point @code{0/0} is assumed but may be overridden (by @code{0/out-dBn}).
1297 Typical values for the transfer function are @code{-70/-70 -60/-20}.
1300 Set amount for which the points at where adjacent line segments on the
1301 transfer function meet will be rounded. Defaults is @code{0.01}.
1304 Set additional gain in dB to be applied at all points on the transfer function
1305 and allows easy adjustment of the overall gain.
1306 Default is @code{0}.
1309 Set initial volume in dB to be assumed for each channel when filtering starts.
1310 This permits the user to supply a nominal level initially, so that,
1311 for example, a very large gain is not applied to initial signal levels before
1312 the companding has begun to operate. A typical value for audio which is
1313 initially quiet is -90 dB. Default is @code{0}.
1316 Set delay in seconds. Default is @code{0}. The input audio
1317 is analysed immediately, but audio is delayed before being fed to the
1318 volume adjuster. Specifying a delay approximately equal to the attack/decay
1319 times allows the filter to effectively operate in predictive rather than
1323 @subsection Examples
1326 Make music with both quiet and loud passages suitable for listening
1327 in a noisy environment:
1329 compand=.3 .3:1 1:-90/-60 -60/-40 -40/-30 -20/-20:6:0:-90:0.2
1333 Noise-gate for when the noise is at a lower level than the signal:
1335 compand=.1 .1:.2 .2:-900/-900 -50.1/-900 -50/-50:.01:0:-90:.1
1339 Here is another noise-gate, this time for when the noise is at a higher level
1340 than the signal (making it, in some ways, similar to squelch):
1342 compand=.1 .1:.1 .1:-45.1/-45.1 -45/-900 0/-900:.01:45:-90:.1
1348 Make audio easier to listen to on headphones.
1350 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1351 so that when listened to on headphones the stereo image is moved from
1352 inside your head (standard for headphones) to outside and in front of
1353 the listener (standard for speakers).
1359 Apply a two-pole peaking equalisation (EQ) filter. With this
1360 filter, the signal-level at and around a selected frequency can
1361 be increased or decreased, whilst (unlike bandpass and bandreject
1362 filters) that at all other frequencies is unchanged.
1364 In order to produce complex equalisation curves, this filter can
1365 be given several times, each with a different central frequency.
1367 The filter accepts the following options:
1371 Set the filter's central frequency in Hz.
1374 Set method to specify band-width of filter.
1387 Specify the band-width of a filter in width_type units.
1390 Set the required gain or attenuation in dB.
1391 Beware of clipping when using a positive gain.
1394 @subsection Examples
1397 Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
1399 equalizer=f=1000:width_type=h:width=200:g=-10
1403 Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
1405 equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
1411 Apply a high-pass filter with 3dB point frequency.
1412 The filter can be either single-pole, or double-pole (the default).
1413 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1415 The filter accepts the following options:
1419 Set frequency in Hz. Default is 3000.
1422 Set number of poles. Default is 2.
1425 Set method to specify band-width of filter.
1438 Specify the band-width of a filter in width_type units.
1439 Applies only to double-pole filter.
1440 The default is 0.707q and gives a Butterworth response.
1445 Join multiple input streams into one multi-channel stream.
1447 The filter accepts the following named parameters:
1451 Number of input streams. Defaults to 2.
1453 @item channel_layout
1454 Desired output channel layout. Defaults to stereo.
1457 Map channels from inputs to output. The argument is a '|'-separated list of
1458 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1459 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1460 can be either the name of the input channel (e.g. FL for front left) or its
1461 index in the specified input stream. @var{out_channel} is the name of the output
1465 The filter will attempt to guess the mappings when those are not specified
1466 explicitly. It does so by first trying to find an unused matching input channel
1467 and if that fails it picks the first unused input channel.
1469 E.g. to join 3 inputs (with properly set channel layouts)
1471 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1474 To build a 5.1 output from 6 single-channel streams:
1476 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1477 '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'
1483 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
1485 To enable compilation of this filter you need to configure FFmpeg with
1486 @code{--enable-ladspa}.
1490 Specifies the name of LADSPA plugin library to load. If the environment
1491 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
1492 each one of the directories specified by the colon separated list in
1493 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
1494 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
1495 @file{/usr/lib/ladspa/}.
1498 Specifies the plugin within the library. Some libraries contain only
1499 one plugin, but others contain many of them. If this is not set filter
1500 will list all available plugins within the specified library.
1503 Set the '|' separated list of controls which are zero or more floating point
1504 values that determine the behavior of the loaded plugin (for example delay,
1506 Controls need to be defined using the following syntax:
1507 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
1508 @var{valuei} is the value set on the @var{i}-th control.
1509 If @option{controls} is set to @code{help}, all available controls and
1510 their valid ranges are printed.
1512 @item sample_rate, s
1513 Specify the sample rate, default to 44100. Only used if plugin have
1517 Set the number of samples per channel per each output frame, default
1518 is 1024. Only used if plugin have zero inputs.
1521 Set the minimum duration of the sourced audio. See the function
1522 @code{av_parse_time()} for the accepted format, also check the "Time duration"
1523 section in the ffmpeg-utils manual.
1524 Note that the resulting duration may be greater than the specified duration,
1525 as the generated audio is always cut at the end of a complete frame.
1526 If not specified, or the expressed duration is negative, the audio is
1527 supposed to be generated forever.
1528 Only used if plugin have zero inputs.
1532 @subsection Examples
1536 List all available plugins within amp (LADSPA example plugin) library:
1542 List all available controls and their valid ranges for @code{vcf_notch}
1543 plugin from @code{VCF} library:
1545 ladspa=f=vcf:p=vcf_notch:c=help
1549 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
1552 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
1556 Add reverberation to the audio using TAP-plugins
1557 (Tom's Audio Processing plugins):
1559 ladspa=file=tap_reverb:tap_reverb
1563 Generate white noise, with 0.2 amplitude:
1565 ladspa=file=cmt:noise_source_white:c=c0=.2
1569 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
1570 @code{C* Audio Plugin Suite} (CAPS) library:
1572 ladspa=file=caps:Click:c=c1=20'
1576 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
1578 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
1582 @subsection Commands
1584 This filter supports the following commands:
1587 Modify the @var{N}-th control value.
1589 If the specified value is not valid, it is ignored and prior one is kept.
1594 Apply a low-pass filter with 3dB point frequency.
1595 The filter can be either single-pole or double-pole (the default).
1596 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1598 The filter accepts the following options:
1602 Set frequency in Hz. Default is 500.
1605 Set number of poles. Default is 2.
1608 Set method to specify band-width of filter.
1621 Specify the band-width of a filter in width_type units.
1622 Applies only to double-pole filter.
1623 The default is 0.707q and gives a Butterworth response.
1628 Mix channels with specific gain levels. The filter accepts the output
1629 channel layout followed by a set of channels definitions.
1631 This filter is also designed to remap efficiently the channels of an audio
1634 The filter accepts parameters of the form:
1635 "@var{l}:@var{outdef}:@var{outdef}:..."
1639 output channel layout or number of channels
1642 output channel specification, of the form:
1643 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1646 output channel to define, either a channel name (FL, FR, etc.) or a channel
1647 number (c0, c1, etc.)
1650 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1653 input channel to use, see out_name for details; it is not possible to mix
1654 named and numbered input channels
1657 If the `=' in a channel specification is replaced by `<', then the gains for
1658 that specification will be renormalized so that the total is 1, thus
1659 avoiding clipping noise.
1661 @subsection Mixing examples
1663 For example, if you want to down-mix from stereo to mono, but with a bigger
1664 factor for the left channel:
1666 pan=1:c0=0.9*c0+0.1*c1
1669 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1670 7-channels surround:
1672 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1675 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1676 that should be preferred (see "-ac" option) unless you have very specific
1679 @subsection Remapping examples
1681 The channel remapping will be effective if, and only if:
1684 @item gain coefficients are zeroes or ones,
1685 @item only one input per channel output,
1688 If all these conditions are satisfied, the filter will notify the user ("Pure
1689 channel mapping detected"), and use an optimized and lossless method to do the
1692 For example, if you have a 5.1 source and want a stereo audio stream by
1693 dropping the extra channels:
1695 pan="stereo: c0=FL : c1=FR"
1698 Given the same source, you can also switch front left and front right channels
1699 and keep the input channel layout:
1701 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1704 If the input is a stereo audio stream, you can mute the front left channel (and
1705 still keep the stereo channel layout) with:
1710 Still with a stereo audio stream input, you can copy the right channel in both
1711 front left and right:
1713 pan="stereo: c0=FR : c1=FR"
1718 ReplayGain scanner filter. This filter takes an audio stream as an input and
1719 outputs it unchanged.
1720 At end of filtering it displays @code{track_gain} and @code{track_peak}.
1724 Convert the audio sample format, sample rate and channel layout. This filter is
1725 not meant to be used directly.
1727 @section silencedetect
1729 Detect silence in an audio stream.
1731 This filter logs a message when it detects that the input audio volume is less
1732 or equal to a noise tolerance value for a duration greater or equal to the
1733 minimum detected noise duration.
1735 The printed times and duration are expressed in seconds.
1737 The filter accepts the following options:
1741 Set silence duration until notification (default is 2 seconds).
1744 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1745 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1748 @subsection Examples
1752 Detect 5 seconds of silence with -50dB noise tolerance:
1754 silencedetect=n=-50dB:d=5
1758 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1759 tolerance in @file{silence.mp3}:
1761 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
1767 Boost or cut treble (upper) frequencies of the audio using a two-pole
1768 shelving filter with a response similar to that of a standard
1769 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1771 The filter accepts the following options:
1775 Give the gain at whichever is the lower of ~22 kHz and the
1776 Nyquist frequency. Its useful range is about -20 (for a large cut)
1777 to +20 (for a large boost). Beware of clipping when using a positive gain.
1780 Set the filter's central frequency and so can be used
1781 to extend or reduce the frequency range to be boosted or cut.
1782 The default value is @code{3000} Hz.
1785 Set method to specify band-width of filter.
1798 Determine how steep is the filter's shelf transition.
1803 Adjust the input audio volume.
1805 The filter accepts the following options:
1810 Set audio volume expression.
1812 Output values are clipped to the maximum value.
1814 The output audio volume is given by the relation:
1816 @var{output_volume} = @var{volume} * @var{input_volume}
1819 Default value for @var{volume} is "1.0".
1822 Set the mathematical precision.
1824 This determines which input sample formats will be allowed, which affects the
1825 precision of the volume scaling.
1829 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1831 32-bit floating-point; limits input sample format to FLT. (default)
1833 64-bit floating-point; limits input sample format to DBL.
1837 Set when the volume expression is evaluated.
1839 It accepts the following values:
1842 only evaluate expression once during the filter initialization, or
1843 when the @samp{volume} command is sent
1846 evaluate expression for each incoming frame
1849 Default value is @samp{once}.
1852 The volume expression can contain the following parameters.
1856 frame number (starting at zero)
1859 @item nb_consumed_samples
1860 number of samples consumed by the filter
1862 number of samples in the current frame
1864 original frame position in the file
1870 PTS at start of stream
1872 time at start of stream
1878 last set volume value
1881 Note that when @option{eval} is set to @samp{once} only the
1882 @var{sample_rate} and @var{tb} variables are available, all other
1883 variables will evaluate to NAN.
1885 @subsection Commands
1887 This filter supports the following commands:
1890 Modify the volume expression.
1891 The command accepts the same syntax of the corresponding option.
1893 If the specified expression is not valid, it is kept at its current
1897 @subsection Examples
1901 Halve the input audio volume:
1905 volume=volume=-6.0206dB
1908 In all the above example the named key for @option{volume} can be
1909 omitted, for example like in:
1915 Increase input audio power by 6 decibels using fixed-point precision:
1917 volume=volume=6dB:precision=fixed
1921 Fade volume after time 10 with an annihilation period of 5 seconds:
1923 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
1927 @section volumedetect
1929 Detect the volume of the input video.
1931 The filter has no parameters. The input is not modified. Statistics about
1932 the volume will be printed in the log when the input stream end is reached.
1934 In particular it will show the mean volume (root mean square), maximum
1935 volume (on a per-sample basis), and the beginning of a histogram of the
1936 registered volume values (from the maximum value to a cumulated 1/1000 of
1939 All volumes are in decibels relative to the maximum PCM value.
1941 @subsection Examples
1943 Here is an excerpt of the output:
1945 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1946 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1947 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1948 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1949 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1950 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1951 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1952 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1953 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1959 The mean square energy is approximately -27 dB, or 10^-2.7.
1961 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1963 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1966 In other words, raising the volume by +4 dB does not cause any clipping,
1967 raising it by +5 dB causes clipping for 6 samples, etc.
1969 @c man end AUDIO FILTERS
1971 @chapter Audio Sources
1972 @c man begin AUDIO SOURCES
1974 Below is a description of the currently available audio sources.
1978 Buffer audio frames, and make them available to the filter chain.
1980 This source is mainly intended for a programmatic use, in particular
1981 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1983 It accepts the following named parameters:
1988 Timebase which will be used for timestamps of submitted frames. It must be
1989 either a floating-point number or in @var{numerator}/@var{denominator} form.
1992 The sample rate of the incoming audio buffers.
1995 The sample format of the incoming audio buffers.
1996 Either a sample format name or its corresponging integer representation from
1997 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1999 @item channel_layout
2000 The channel layout of the incoming audio buffers.
2001 Either a channel layout name from channel_layout_map in
2002 @file{libavutil/channel_layout.c} or its corresponding integer representation
2003 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
2006 The number of channels of the incoming audio buffers.
2007 If both @var{channels} and @var{channel_layout} are specified, then they
2012 @subsection Examples
2015 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
2018 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
2019 Since the sample format with name "s16p" corresponds to the number
2020 6 and the "stereo" channel layout corresponds to the value 0x3, this is
2023 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
2028 Generate an audio signal specified by an expression.
2030 This source accepts in input one or more expressions (one for each
2031 channel), which are evaluated and used to generate a corresponding
2034 This source accepts the following options:
2038 Set the '|'-separated expressions list for each separate channel. In case the
2039 @option{channel_layout} option is not specified, the selected channel layout
2040 depends on the number of provided expressions. Otherwise the last
2041 specified expression is applied to the remaining output channels.
2043 @item channel_layout, c
2044 Set the channel layout. The number of channels in the specified layout
2045 must be equal to the number of specified expressions.
2048 Set the minimum duration of the sourced audio. See the function
2049 @code{av_parse_time()} for the accepted format.
2050 Note that the resulting duration may be greater than the specified
2051 duration, as the generated audio is always cut at the end of a
2054 If not specified, or the expressed duration is negative, the audio is
2055 supposed to be generated forever.
2058 Set the number of samples per channel per each output frame,
2061 @item sample_rate, s
2062 Specify the sample rate, default to 44100.
2065 Each expression in @var{exprs} can contain the following constants:
2069 number of the evaluated sample, starting from 0
2072 time of the evaluated sample expressed in seconds, starting from 0
2079 @subsection Examples
2089 Generate a sin signal with frequency of 440 Hz, set sample rate to
2092 aevalsrc="sin(440*2*PI*t):s=8000"
2096 Generate a two channels signal, specify the channel layout (Front
2097 Center + Back Center) explicitly:
2099 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
2103 Generate white noise:
2105 aevalsrc="-2+random(0)"
2109 Generate an amplitude modulated signal:
2111 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
2115 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
2117 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
2124 Null audio source, return unprocessed audio frames. It is mainly useful
2125 as a template and to be employed in analysis / debugging tools, or as
2126 the source for filters which ignore the input data (for example the sox
2129 This source accepts the following options:
2133 @item channel_layout, cl
2135 Specify the channel layout, and can be either an integer or a string
2136 representing a channel layout. The default value of @var{channel_layout}
2139 Check the channel_layout_map definition in
2140 @file{libavutil/channel_layout.c} for the mapping between strings and
2141 channel layout values.
2143 @item sample_rate, r
2144 Specify the sample rate, and defaults to 44100.
2147 Set the number of samples per requested frames.
2151 @subsection Examples
2155 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
2157 anullsrc=r=48000:cl=4
2161 Do the same operation with a more obvious syntax:
2163 anullsrc=r=48000:cl=mono
2167 All the parameters need to be explicitly defined.
2171 Synthesize a voice utterance using the libflite library.
2173 To enable compilation of this filter you need to configure FFmpeg with
2174 @code{--enable-libflite}.
2176 Note that the flite library is not thread-safe.
2178 The filter accepts the following options:
2183 If set to 1, list the names of the available voices and exit
2184 immediately. Default value is 0.
2187 Set the maximum number of samples per frame. Default value is 512.
2190 Set the filename containing the text to speak.
2193 Set the text to speak.
2196 Set the voice to use for the speech synthesis. Default value is
2197 @code{kal}. See also the @var{list_voices} option.
2200 @subsection Examples
2204 Read from file @file{speech.txt}, and synthetize the text using the
2205 standard flite voice:
2207 flite=textfile=speech.txt
2211 Read the specified text selecting the @code{slt} voice:
2213 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2217 Input text to ffmpeg:
2219 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2223 Make @file{ffplay} speak the specified text, using @code{flite} and
2224 the @code{lavfi} device:
2226 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
2230 For more information about libflite, check:
2231 @url{http://www.speech.cs.cmu.edu/flite/}
2235 Generate an audio signal made of a sine wave with amplitude 1/8.
2237 The audio signal is bit-exact.
2239 The filter accepts the following options:
2244 Set the carrier frequency. Default is 440 Hz.
2246 @item beep_factor, b
2247 Enable a periodic beep every second with frequency @var{beep_factor} times
2248 the carrier frequency. Default is 0, meaning the beep is disabled.
2250 @item sample_rate, r
2251 Specify the sample rate, default is 44100.
2254 Specify the duration of the generated audio stream.
2256 @item samples_per_frame
2257 Set the number of samples per output frame, default is 1024.
2260 @subsection Examples
2265 Generate a simple 440 Hz sine wave:
2271 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
2275 sine=frequency=220:beep_factor=4:duration=5
2280 @c man end AUDIO SOURCES
2282 @chapter Audio Sinks
2283 @c man begin AUDIO SINKS
2285 Below is a description of the currently available audio sinks.
2287 @section abuffersink
2289 Buffer audio frames, and make them available to the end of filter chain.
2291 This sink is mainly intended for programmatic use, in particular
2292 through the interface defined in @file{libavfilter/buffersink.h}
2293 or the options system.
2295 It accepts a pointer to an AVABufferSinkContext structure, which
2296 defines the incoming buffers' formats, to be passed as the opaque
2297 parameter to @code{avfilter_init_filter} for initialization.
2301 Null audio sink, do absolutely nothing with the input audio. It is
2302 mainly useful as a template and to be employed in analysis / debugging
2305 @c man end AUDIO SINKS
2307 @chapter Video Filters
2308 @c man begin VIDEO FILTERS
2310 When you configure your FFmpeg build, you can disable any of the
2311 existing filters using @code{--disable-filters}.
2312 The configure output will show the video filters included in your
2315 Below is a description of the currently available video filters.
2317 @section alphaextract
2319 Extract the alpha component from the input as a grayscale video. This
2320 is especially useful with the @var{alphamerge} filter.
2324 Add or replace the alpha component of the primary input with the
2325 grayscale value of a second input. This is intended for use with
2326 @var{alphaextract} to allow the transmission or storage of frame
2327 sequences that have alpha in a format that doesn't support an alpha
2330 For example, to reconstruct full frames from a normal YUV-encoded video
2331 and a separate video created with @var{alphaextract}, you might use:
2333 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
2336 Since this filter is designed for reconstruction, it operates on frame
2337 sequences without considering timestamps, and terminates when either
2338 input reaches end of stream. This will cause problems if your encoding
2339 pipeline drops frames. If you're trying to apply an image as an
2340 overlay to a video stream, consider the @var{overlay} filter instead.
2344 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
2345 and libavformat to work. On the other hand, it is limited to ASS (Advanced
2346 Substation Alpha) subtitles files.
2350 Compute the bounding box for the non-black pixels in the input frame
2353 This filter computes the bounding box containing all the pixels with a
2354 luminance value greater than the minimum allowed value.
2355 The parameters describing the bounding box are printed on the filter
2358 The filter accepts the following option:
2362 Set the minimal luminance value. Default is @code{16}.
2365 @section blackdetect
2367 Detect video intervals that are (almost) completely black. Can be
2368 useful to detect chapter transitions, commercials, or invalid
2369 recordings. Output lines contains the time for the start, end and
2370 duration of the detected black interval expressed in seconds.
2372 In order to display the output lines, you need to set the loglevel at
2373 least to the AV_LOG_INFO value.
2375 The filter accepts the following options:
2378 @item black_min_duration, d
2379 Set the minimum detected black duration expressed in seconds. It must
2380 be a non-negative floating point number.
2382 Default value is 2.0.
2384 @item picture_black_ratio_th, pic_th
2385 Set the threshold for considering a picture "black".
2386 Express the minimum value for the ratio:
2388 @var{nb_black_pixels} / @var{nb_pixels}
2391 for which a picture is considered black.
2392 Default value is 0.98.
2394 @item pixel_black_th, pix_th
2395 Set the threshold for considering a pixel "black".
2397 The threshold expresses the maximum pixel luminance value for which a
2398 pixel is considered "black". The provided value is scaled according to
2399 the following equation:
2401 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
2404 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
2405 the input video format, the range is [0-255] for YUV full-range
2406 formats and [16-235] for YUV non full-range formats.
2408 Default value is 0.10.
2411 The following example sets the maximum pixel threshold to the minimum
2412 value, and detects only black intervals of 2 or more seconds:
2414 blackdetect=d=2:pix_th=0.00
2419 Detect frames that are (almost) completely black. Can be useful to
2420 detect chapter transitions or commercials. Output lines consist of
2421 the frame number of the detected frame, the percentage of blackness,
2422 the position in the file if known or -1 and the timestamp in seconds.
2424 In order to display the output lines, you need to set the loglevel at
2425 least to the AV_LOG_INFO value.
2427 The filter accepts the following options:
2432 Set the percentage of the pixels that have to be below the threshold, defaults
2435 @item threshold, thresh
2436 Set the threshold below which a pixel value is considered black, defaults to
2443 Blend two video frames into each other.
2445 It takes two input streams and outputs one stream, the first input is the
2446 "top" layer and second input is "bottom" layer.
2447 Output terminates when shortest input terminates.
2449 A description of the accepted options follows.
2457 Set blend mode for specific pixel component or all pixel components in case
2458 of @var{all_mode}. Default value is @code{normal}.
2460 Available values for component modes are:
2493 Set blend opacity for specific pixel component or all pixel components in case
2494 of @var{all_opacity}. Only used in combination with pixel component blend modes.
2501 Set blend expression for specific pixel component or all pixel components in case
2502 of @var{all_expr}. Note that related mode options will be ignored if those are set.
2504 The expressions can use the following variables:
2508 The sequential number of the filtered frame, starting from @code{0}.
2512 the coordinates of the current sample
2516 the width and height of currently filtered plane
2520 Width and height scale depending on the currently filtered plane. It is the
2521 ratio between the corresponding luma plane number of pixels and the current
2522 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2523 @code{0.5,0.5} for chroma planes.
2526 Time of the current frame, expressed in seconds.
2529 Value of pixel component at current location for first video frame (top layer).
2532 Value of pixel component at current location for second video frame (bottom layer).
2536 Force termination when the shortest input terminates. Default is @code{0}.
2538 Continue applying the last bottom frame after the end of the stream. A value of
2539 @code{0} disable the filter after the last frame of the bottom layer is reached.
2540 Default is @code{1}.
2543 @subsection Examples
2547 Apply transition from bottom layer to top layer in first 10 seconds:
2549 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2553 Apply 1x1 checkerboard effect:
2555 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2559 Apply uncover left effect:
2561 blend=all_expr='if(gte(N*SW+X,W),A,B)'
2565 Apply uncover down effect:
2567 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
2571 Apply uncover up-left effect:
2573 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
2579 Apply boxblur algorithm to the input video.
2581 The filter accepts the following options:
2585 @item luma_radius, lr
2586 @item luma_power, lp
2587 @item chroma_radius, cr
2588 @item chroma_power, cp
2589 @item alpha_radius, ar
2590 @item alpha_power, ap
2594 A description of the accepted options follows.
2597 @item luma_radius, lr
2598 @item chroma_radius, cr
2599 @item alpha_radius, ar
2600 Set an expression for the box radius in pixels used for blurring the
2601 corresponding input plane.
2603 The radius value must be a non-negative number, and must not be
2604 greater than the value of the expression @code{min(w,h)/2} for the
2605 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2608 Default value for @option{luma_radius} is "2". If not specified,
2609 @option{chroma_radius} and @option{alpha_radius} default to the
2610 corresponding value set for @option{luma_radius}.
2612 The expressions can contain the following constants:
2616 the input width and height in pixels
2620 the input chroma image width and height in pixels
2624 horizontal and vertical chroma subsample values. For example for the
2625 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2628 @item luma_power, lp
2629 @item chroma_power, cp
2630 @item alpha_power, ap
2631 Specify how many times the boxblur filter is applied to the
2632 corresponding plane.
2634 Default value for @option{luma_power} is 2. If not specified,
2635 @option{chroma_power} and @option{alpha_power} default to the
2636 corresponding value set for @option{luma_power}.
2638 A value of 0 will disable the effect.
2641 @subsection Examples
2645 Apply a boxblur filter with luma, chroma, and alpha radius
2648 boxblur=luma_radius=2:luma_power=1
2653 Set luma radius to 2, alpha and chroma radius to 0:
2655 boxblur=2:1:cr=0:ar=0
2659 Set luma and chroma radius to a fraction of the video dimension:
2661 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2665 @section colorbalance
2666 Modify intensity of primary colors (red, green and blue) of input frames.
2668 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
2669 regions for the red-cyan, green-magenta or blue-yellow balance.
2671 A positive adjustment value shifts the balance towards the primary color, a negative
2672 value towards the complementary color.
2674 The filter accepts the following options:
2680 Adjust red, green and blue shadows (darkest pixels).
2685 Adjust red, green and blue midtones (medium pixels).
2690 Adjust red, green and blue highlights (brightest pixels).
2692 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
2695 @subsection Examples
2699 Add red color cast to shadows:
2705 @section colorchannelmixer
2707 Adjust video input frames by re-mixing color channels.
2709 This filter modifies a color channel by adding the values associated to
2710 the other channels of the same pixels. For example if the value to
2711 modify is red, the output value will be:
2713 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
2716 The filter accepts the following options:
2723 Adjust contribution of input red, green, blue and alpha channels for output red channel.
2724 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
2730 Adjust contribution of input red, green, blue and alpha channels for output green channel.
2731 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
2737 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
2738 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
2744 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
2745 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
2747 Allowed ranges for options are @code{[-2.0, 2.0]}.
2750 @subsection Examples
2754 Convert source to grayscale:
2756 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
2759 Simulate sepia tones:
2761 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
2765 @section colormatrix
2767 Convert color matrix.
2769 The filter accepts the following options:
2774 Specify the source and destination color matrix. Both values must be
2777 The accepted values are:
2793 For example to convert from BT.601 to SMPTE-240M, use the command:
2795 colormatrix=bt601:smpte240m
2800 Copy the input source unchanged to the output. Mainly useful for
2805 Crop the input video to given dimensions.
2807 The filter accepts the following options:
2811 Width of the output video. It defaults to @code{iw}.
2812 This expression is evaluated only once during the filter
2816 Height of the output video. It defaults to @code{ih}.
2817 This expression is evaluated only once during the filter
2821 Horizontal position, in the input video, of the left edge of the output video.
2822 It defaults to @code{(in_w-out_w)/2}.
2823 This expression is evaluated per-frame.
2826 Vertical position, in the input video, of the top edge of the output video.
2827 It defaults to @code{(in_h-out_h)/2}.
2828 This expression is evaluated per-frame.
2831 If set to 1 will force the output display aspect ratio
2832 to be the same of the input, by changing the output sample aspect
2833 ratio. It defaults to 0.
2836 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2837 expressions containing the following constants:
2842 the computed values for @var{x} and @var{y}. They are evaluated for
2847 the input width and height
2851 same as @var{in_w} and @var{in_h}
2855 the output (cropped) width and height
2859 same as @var{out_w} and @var{out_h}
2862 same as @var{iw} / @var{ih}
2865 input sample aspect ratio
2868 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2872 horizontal and vertical chroma subsample values. For example for the
2873 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2876 the number of input frame, starting from 0
2879 the position in the file of the input frame, NAN if unknown
2882 timestamp expressed in seconds, NAN if the input timestamp is unknown
2886 The expression for @var{out_w} may depend on the value of @var{out_h},
2887 and the expression for @var{out_h} may depend on @var{out_w}, but they
2888 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2889 evaluated after @var{out_w} and @var{out_h}.
2891 The @var{x} and @var{y} parameters specify the expressions for the
2892 position of the top-left corner of the output (non-cropped) area. They
2893 are evaluated for each frame. If the evaluated value is not valid, it
2894 is approximated to the nearest valid value.
2896 The expression for @var{x} may depend on @var{y}, and the expression
2897 for @var{y} may depend on @var{x}.
2899 @subsection Examples
2903 Crop area with size 100x100 at position (12,34).
2908 Using named options, the example above becomes:
2910 crop=w=100:h=100:x=12:y=34
2914 Crop the central input area with size 100x100:
2920 Crop the central input area with size 2/3 of the input video:
2922 crop=2/3*in_w:2/3*in_h
2926 Crop the input video central square:
2933 Delimit the rectangle with the top-left corner placed at position
2934 100:100 and the right-bottom corner corresponding to the right-bottom
2935 corner of the input image:
2937 crop=in_w-100:in_h-100:100:100
2941 Crop 10 pixels from the left and right borders, and 20 pixels from
2942 the top and bottom borders
2944 crop=in_w-2*10:in_h-2*20
2948 Keep only the bottom right quarter of the input image:
2950 crop=in_w/2:in_h/2:in_w/2:in_h/2
2954 Crop height for getting Greek harmony:
2956 crop=in_w:1/PHI*in_w
2960 Appply trembling effect:
2962 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)
2966 Apply erratic camera effect depending on timestamp:
2968 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)"
2972 Set x depending on the value of y:
2974 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2980 Auto-detect crop size.
2982 Calculate necessary cropping parameters and prints the recommended
2983 parameters through the logging system. The detected dimensions
2984 correspond to the non-black area of the input video.
2986 The filter accepts the following options:
2991 Set higher black value threshold, which can be optionally specified
2992 from nothing (0) to everything (255). An intensity value greater
2993 to the set value is considered non-black. Default value is 24.
2996 Set the value for which the width/height should be divisible by. The
2997 offset is automatically adjusted to center the video. Use 2 to get
2998 only even dimensions (needed for 4:2:2 video). 16 is best when
2999 encoding to most video codecs. Default value is 16.
3001 @item reset_count, reset
3002 Set the counter that determines after how many frames cropdetect will
3003 reset the previously detected largest video area and start over to
3004 detect the current optimal crop area. Default value is 0.
3006 This can be useful when channel logos distort the video area. 0
3007 indicates never reset and return the largest area encountered during
3014 Apply color adjustments using curves.
3016 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
3017 component (red, green and blue) has its values defined by @var{N} key points
3018 tied from each other using a smooth curve. The x-axis represents the pixel
3019 values from the input frame, and the y-axis the new pixel values to be set for
3022 By default, a component curve is defined by the two points @var{(0;0)} and
3023 @var{(1;1)}. This creates a straight line where each original pixel value is
3024 "adjusted" to its own value, which means no change to the image.
3026 The filter allows you to redefine these two points and add some more. A new
3027 curve (using a natural cubic spline interpolation) will be define to pass
3028 smoothly through all these new coordinates. The new defined points needs to be
3029 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
3030 be in the @var{[0;1]} interval. If the computed curves happened to go outside
3031 the vector spaces, the values will be clipped accordingly.
3033 If there is no key point defined in @code{x=0}, the filter will automatically
3034 insert a @var{(0;0)} point. In the same way, if there is no key point defined
3035 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
3037 The filter accepts the following options:
3041 Select one of the available color presets. This option can be used in addition
3042 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
3043 options takes priority on the preset values.
3044 Available presets are:
3047 @item color_negative
3050 @item increase_contrast
3052 @item linear_contrast
3053 @item medium_contrast
3055 @item strong_contrast
3058 Default is @code{none}.
3060 Set the master key points. These points will define a second pass mapping. It
3061 is sometimes called a "luminance" or "value" mapping. It can be used with
3062 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
3063 post-processing LUT.
3065 Set the key points for the red component.
3067 Set the key points for the green component.
3069 Set the key points for the blue component.
3071 Set the key points for all components (not including master).
3072 Can be used in addition to the other key points component
3073 options. In this case, the unset component(s) will fallback on this
3074 @option{all} setting.
3076 Specify a Photoshop curves file (@code{.asv}) to import the settings from.
3079 To avoid some filtergraph syntax conflicts, each key points list need to be
3080 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
3082 @subsection Examples
3086 Increase slightly the middle level of blue:
3088 curves=blue='0.5/0.58'
3094 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
3096 Here we obtain the following coordinates for each components:
3099 @code{(0;0.11) (0.42;0.51) (1;0.95)}
3101 @code{(0;0) (0.50;0.48) (1;1)}
3103 @code{(0;0.22) (0.49;0.44) (1;0.80)}
3107 The previous example can also be achieved with the associated built-in preset:
3109 curves=preset=vintage
3119 Use a Photoshop preset and redefine the points of the green component:
3121 curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53'
3127 Denoise frames using 2D DCT (frequency domain filtering).
3129 This filter is not designed for real time and can be extremely slow.
3131 The filter accepts the following options:
3135 Set the noise sigma constant.
3137 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
3138 coefficient (absolute value) below this threshold with be dropped.
3140 If you need a more advanced filtering, see @option{expr}.
3142 Default is @code{0}.
3145 Set number overlapping pixels for each block. Each block is of size
3146 @code{16x16}. Since the filter can be slow, you may want to reduce this value,
3147 at the cost of a less effective filter and the risk of various artefacts.
3149 If the overlapping value doesn't allow to process the whole input width or
3150 height, a warning will be displayed and according borders won't be denoised.
3152 Default value is @code{15}.
3155 Set the coefficient factor expression.
3157 For each coefficient of a DCT block, this expression will be evaluated as a
3158 multiplier value for the coefficient.
3160 If this is option is set, the @option{sigma} option will be ignored.
3162 The absolute value of the coefficient can be accessed through the @var{c}
3166 @subsection Examples
3168 Apply a denoise with a @option{sigma} of @code{4.5}:
3173 The same operation can be achieved using the expression system:
3175 dctdnoiz=e='gte(c, 4.5*3)'
3181 Drop duplicated frames at regular intervals.
3183 The filter accepts the following options:
3187 Set the number of frames from which one will be dropped. Setting this to
3188 @var{N} means one frame in every batch of @var{N} frames will be dropped.
3189 Default is @code{5}.
3192 Set the threshold for duplicate detection. If the difference metric for a frame
3193 is less than or equal to this value, then it is declared as duplicate. Default
3197 Set scene change threshold. Default is @code{15}.
3201 Set the size of the x and y-axis blocks used during metric calculations.
3202 Larger blocks give better noise suppression, but also give worse detection of
3203 small movements. Must be a power of two. Default is @code{32}.
3206 Mark main input as a pre-processed input and activate clean source input
3207 stream. This allows the input to be pre-processed with various filters to help
3208 the metrics calculation while keeping the frame selection lossless. When set to
3209 @code{1}, the first stream is for the pre-processed input, and the second
3210 stream is the clean source from where the kept frames are chosen. Default is
3214 Set whether or not chroma is considered in the metric calculations. Default is
3220 Suppress a TV station logo by a simple interpolation of the surrounding
3221 pixels. Just set a rectangle covering the logo and watch it disappear
3222 (and sometimes something even uglier appear - your mileage may vary).
3224 This filter accepts the following options:
3229 Specify the top left corner coordinates of the logo. They must be
3234 Specify the width and height of the logo to clear. They must be
3238 Specify the thickness of the fuzzy edge of the rectangle (added to
3239 @var{w} and @var{h}). The default value is 4.
3242 When set to 1, a green rectangle is drawn on the screen to simplify
3243 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
3244 The default value is 0.
3246 The rectangle is drawn on the outermost pixels which will be (partly)
3247 replaced with interpolated values. The values of the next pixels
3248 immediately outside this rectangle in each direction will be used to
3249 compute the interpolated pixel values inside the rectangle.
3253 @subsection Examples
3257 Set a rectangle covering the area with top left corner coordinates 0,0
3258 and size 100x77, setting a band of size 10:
3260 delogo=x=0:y=0:w=100:h=77:band=10
3267 Attempt to fix small changes in horizontal and/or vertical shift. This
3268 filter helps remove camera shake from hand-holding a camera, bumping a
3269 tripod, moving on a vehicle, etc.
3271 The filter accepts the following options:
3279 Specify a rectangular area where to limit the search for motion
3281 If desired the search for motion vectors can be limited to a
3282 rectangular area of the frame defined by its top left corner, width
3283 and height. These parameters have the same meaning as the drawbox
3284 filter which can be used to visualise the position of the bounding
3287 This is useful when simultaneous movement of subjects within the frame
3288 might be confused for camera motion by the motion vector search.
3290 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
3291 then the full frame is used. This allows later options to be set
3292 without specifying the bounding box for the motion vector search.
3294 Default - search the whole frame.
3298 Specify the maximum extent of movement in x and y directions in the
3299 range 0-64 pixels. Default 16.
3302 Specify how to generate pixels to fill blanks at the edge of the
3303 frame. Available values are:
3306 Fill zeroes at blank locations
3308 Original image at blank locations
3310 Extruded edge value at blank locations
3312 Mirrored edge at blank locations
3314 Default value is @samp{mirror}.
3317 Specify the blocksize to use for motion search. Range 4-128 pixels,
3321 Specify the contrast threshold for blocks. Only blocks with more than
3322 the specified contrast (difference between darkest and lightest
3323 pixels) will be considered. Range 1-255, default 125.
3326 Specify the search strategy. Available values are:
3329 Set exhaustive search
3331 Set less exhaustive search.
3333 Default value is @samp{exhaustive}.
3336 If set then a detailed log of the motion search is written to the
3340 If set to 1, specify using OpenCL capabilities, only available if
3341 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
3347 Draw a colored box on the input image.
3349 This filter accepts the following options:
3354 The expressions which specify the top left corner coordinates of the box. Default to 0.
3358 The expressions which specify the width and height of the box, if 0 they are interpreted as
3359 the input width and height. Default to 0.
3362 Specify the color of the box to write. For the general syntax of this option,
3363 check the "Color" section in the ffmpeg-utils manual. If the special
3364 value @code{invert} is used, the box edge color is the same as the
3365 video with inverted luma.
3368 The expression which sets the thickness of the box edge. Default value is @code{3}.
3370 See below for the list of accepted constants.
3373 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3374 following constants:
3378 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3382 horizontal and vertical chroma subsample values. For example for the
3383 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3387 The input width and height.
3390 The input sample aspect ratio.
3394 The x and y offset coordinates where the box is drawn.
3398 The width and height of the drawn box.
3401 The thickness of the drawn box.
3403 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3404 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3408 @subsection Examples
3412 Draw a black box around the edge of the input image:
3418 Draw a box with color red and an opacity of 50%:
3420 drawbox=10:20:200:60:red@@0.5
3423 The previous example can be specified as:
3425 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
3429 Fill the box with pink color:
3431 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
3435 Draw a 2-pixel red 2.40:1 mask:
3437 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
3443 Draw a grid on the input image.
3445 This filter accepts the following options:
3450 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
3454 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
3455 input width and height, respectively, minus @code{thickness}, so image gets
3456 framed. Default to 0.
3459 Specify the color of the grid. For the general syntax of this option,
3460 check the "Color" section in the ffmpeg-utils manual. If the special
3461 value @code{invert} is used, the grid color is the same as the
3462 video with inverted luma.
3465 The expression which sets the thickness of the grid line. Default value is @code{1}.
3467 See below for the list of accepted constants.
3470 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3471 following constants:
3475 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3479 horizontal and vertical chroma subsample values. For example for the
3480 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3484 The input grid cell width and height.
3487 The input sample aspect ratio.
3491 The x and y coordinates of some point of grid intersection (meant to configure offset).
3495 The width and height of the drawn cell.
3498 The thickness of the drawn cell.
3500 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3501 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3505 @subsection Examples
3509 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
3511 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
3515 Draw a white 3x3 grid with an opacity of 50%:
3517 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
3524 Draw text string or text from specified file on top of video using the
3525 libfreetype library.
3527 To enable compilation of this filter you need to configure FFmpeg with
3528 @code{--enable-libfreetype}.
3532 The description of the accepted parameters follows.
3537 Used to draw a box around text using background color.
3538 Value should be either 1 (enable) or 0 (disable).
3539 The default value of @var{box} is 0.
3542 The color to be used for drawing box around text. For the syntax of this
3543 option, check the "Color" section in the ffmpeg-utils manual.
3545 The default value of @var{boxcolor} is "white".
3548 Set the width of the border to be drawn around the text using @var{bordercolor}.
3549 The default value of @var{borderw} is 0.
3552 Set the color to be used for drawing border around text. For the syntax of this
3553 option, check the "Color" section in the ffmpeg-utils manual.
3555 The default value of @var{bordercolor} is "black".
3558 Select how the @var{text} is expanded. Can be either @code{none},
3559 @code{strftime} (deprecated) or
3560 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
3564 If true, check and fix text coords to avoid clipping.
3567 The color to be used for drawing fonts. For the syntax of this option, check
3568 the "Color" section in the ffmpeg-utils manual.
3570 The default value of @var{fontcolor} is "black".
3573 The font file to be used for drawing text. Path must be included.
3574 This parameter is mandatory.
3577 The font size to be used for drawing text.
3578 The default value of @var{fontsize} is 16.
3581 Flags to be used for loading the fonts.
3583 The flags map the corresponding flags supported by libfreetype, and are
3584 a combination of the following values:
3591 @item vertical_layout
3592 @item force_autohint
3595 @item ignore_global_advance_width
3597 @item ignore_transform
3603 Default value is "default".
3605 For more information consult the documentation for the FT_LOAD_*
3609 The color to be used for drawing a shadow behind the drawn text. For the
3610 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
3612 The default value of @var{shadowcolor} is "black".
3616 The x and y offsets for the text shadow position with respect to the
3617 position of the text. They can be either positive or negative
3618 values. Default value for both is "0".
3621 The starting frame number for the n/frame_num variable. The default value
3625 The size in number of spaces to use for rendering the tab.
3629 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
3630 format. It can be used with or without text parameter. @var{timecode_rate}
3631 option must be specified.
3633 @item timecode_rate, rate, r
3634 Set the timecode frame rate (timecode only).
3637 The text string to be drawn. The text must be a sequence of UTF-8
3639 This parameter is mandatory if no file is specified with the parameter
3643 A text file containing text to be drawn. The text must be a sequence
3644 of UTF-8 encoded characters.
3646 This parameter is mandatory if no text string is specified with the
3647 parameter @var{text}.
3649 If both @var{text} and @var{textfile} are specified, an error is thrown.
3652 If set to 1, the @var{textfile} will be reloaded before each frame.
3653 Be sure to update it atomically, or it may be read partially, or even fail.
3657 The expressions which specify the offsets where text will be drawn
3658 within the video frame. They are relative to the top/left border of the
3661 The default value of @var{x} and @var{y} is "0".
3663 See below for the list of accepted constants and functions.
3666 The parameters for @var{x} and @var{y} are expressions containing the
3667 following constants and functions:
3671 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
3675 horizontal and vertical chroma subsample values. For example for the
3676 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3679 the height of each text line
3687 @item max_glyph_a, ascent
3688 the maximum distance from the baseline to the highest/upper grid
3689 coordinate used to place a glyph outline point, for all the rendered
3691 It is a positive value, due to the grid's orientation with the Y axis
3694 @item max_glyph_d, descent
3695 the maximum distance from the baseline to the lowest grid coordinate
3696 used to place a glyph outline point, for all the rendered glyphs.
3697 This is a negative value, due to the grid's orientation, with the Y axis
3701 maximum glyph height, that is the maximum height for all the glyphs
3702 contained in the rendered text, it is equivalent to @var{ascent} -
3706 maximum glyph width, that is the maximum width for all the glyphs
3707 contained in the rendered text
3710 the number of input frame, starting from 0
3712 @item rand(min, max)
3713 return a random number included between @var{min} and @var{max}
3716 input sample aspect ratio
3719 timestamp expressed in seconds, NAN if the input timestamp is unknown
3722 the height of the rendered text
3725 the width of the rendered text
3729 the x and y offset coordinates where the text is drawn.
3731 These parameters allow the @var{x} and @var{y} expressions to refer
3732 each other, so you can for example specify @code{y=x/dar}.
3735 If libavfilter was built with @code{--enable-fontconfig}, then
3736 @option{fontfile} can be a fontconfig pattern or omitted.
3738 @anchor{drawtext_expansion}
3739 @subsection Text expansion
3741 If @option{expansion} is set to @code{strftime},
3742 the filter recognizes strftime() sequences in the provided text and
3743 expands them accordingly. Check the documentation of strftime(). This
3744 feature is deprecated.
3746 If @option{expansion} is set to @code{none}, the text is printed verbatim.
3748 If @option{expansion} is set to @code{normal} (which is the default),
3749 the following expansion mechanism is used.
3751 The backslash character '\', followed by any character, always expands to
3752 the second character.
3754 Sequence of the form @code{%@{...@}} are expanded. The text between the
3755 braces is a function name, possibly followed by arguments separated by ':'.
3756 If the arguments contain special characters or delimiters (':' or '@}'),
3757 they should be escaped.
3759 Note that they probably must also be escaped as the value for the
3760 @option{text} option in the filter argument string and as the filter
3761 argument in the filtergraph description, and possibly also for the shell,
3762 that makes up to four levels of escaping; using a text file avoids these
3765 The following functions are available:
3770 The expression evaluation result.
3772 It must take one argument specifying the expression to be evaluated,
3773 which accepts the same constants and functions as the @var{x} and
3774 @var{y} values. Note that not all constants should be used, for
3775 example the text size is not known when evaluating the expression, so
3776 the constants @var{text_w} and @var{text_h} will have an undefined
3780 The time at which the filter is running, expressed in UTC.
3781 It can accept an argument: a strftime() format string.
3784 The time at which the filter is running, expressed in the local time zone.
3785 It can accept an argument: a strftime() format string.
3788 Frame metadata. It must take one argument specifying metadata key.
3791 The frame number, starting from 0.
3794 A 1 character description of the current picture type.
3797 The timestamp of the current frame, in seconds, with microsecond accuracy.
3801 @subsection Examples
3805 Draw "Test Text" with font FreeSerif, using the default values for the
3806 optional parameters.
3809 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
3813 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
3814 and y=50 (counting from the top-left corner of the screen), text is
3815 yellow with a red box around it. Both the text and the box have an
3819 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
3820 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
3823 Note that the double quotes are not necessary if spaces are not used
3824 within the parameter list.
3827 Show the text at the center of the video frame:
3829 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
3833 Show a text line sliding from right to left in the last row of the video
3834 frame. The file @file{LONG_LINE} is assumed to contain a single line
3837 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3841 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3843 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3847 Draw a single green letter "g", at the center of the input video.
3848 The glyph baseline is placed at half screen height.
3850 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3854 Show text for 1 second every 3 seconds:
3856 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
3860 Use fontconfig to set the font. Note that the colons need to be escaped.
3862 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3866 Print the date of a real-time encoding (see strftime(3)):
3868 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3873 For more information about libfreetype, check:
3874 @url{http://www.freetype.org/}.
3876 For more information about fontconfig, check:
3877 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3881 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3883 The filter accepts the following options:
3888 Set low and high threshold values used by the Canny thresholding
3891 The high threshold selects the "strong" edge pixels, which are then
3892 connected through 8-connectivity with the "weak" edge pixels selected
3893 by the low threshold.
3895 @var{low} and @var{high} threshold values must be choosen in the range
3896 [0,1], and @var{low} should be lesser or equal to @var{high}.
3898 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3904 edgedetect=low=0.1:high=0.4
3907 @section extractplanes
3909 Extract color channel components from input video stream into
3910 separate grayscale video streams.
3912 The filter accepts the following option:
3916 Set plane(s) to extract.
3918 Available values for planes are:
3929 Choosing planes not available in the input will result in an error.
3930 That means you cannot select @code{r}, @code{g}, @code{b} planes
3931 with @code{y}, @code{u}, @code{v} planes at same time.
3934 @subsection Examples
3938 Extract luma, u and v color channel component from input video frame
3939 into 3 grayscale outputs:
3941 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
3947 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
3949 For each input image, the filter will compute the optimal mapping from
3950 the input to the output given the codebook length, that is the number
3951 of distinct output colors.
3953 This filter accepts the following options.
3956 @item codebook_length, l
3957 Set codebook length. The value must be a positive integer, and
3958 represents the number of distinct output colors. Default value is 256.
3961 Set the maximum number of iterations to apply for computing the optimal
3962 mapping. The higher the value the better the result and the higher the
3963 computation time. Default value is 1.
3966 Set a random seed, must be an integer included between 0 and
3967 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
3968 will try to use a good random seed on a best effort basis.
3973 Apply fade-in/out effect to input video.
3975 This filter accepts the following options:
3979 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3981 Default is @code{in}.
3983 @item start_frame, s
3984 Specify the number of the start frame for starting to apply the fade
3985 effect. Default is 0.
3988 The number of frames for which the fade effect has to last. At the end of the
3989 fade-in effect the output video will have the same intensity as the input video,
3990 at the end of the fade-out transition the output video will be filled with the
3991 selected @option{color}.
3995 If set to 1, fade only alpha channel, if one exists on the input.
3998 @item start_time, st
3999 Specify the timestamp (in seconds) of the frame to start to apply the fade
4000 effect. If both start_frame and start_time are specified, the fade will start at
4001 whichever comes last. Default is 0.
4004 The number of seconds for which the fade effect has to last. At the end of the
4005 fade-in effect the output video will have the same intensity as the input video,
4006 at the end of the fade-out transition the output video will be filled with the
4007 selected @option{color}.
4008 If both duration and nb_frames are specified, duration is used. Default is 0.
4011 Specify the color of the fade. Default is "black".
4014 @subsection Examples
4018 Fade in first 30 frames of video:
4023 The command above is equivalent to:
4029 Fade out last 45 frames of a 200-frame video:
4032 fade=type=out:start_frame=155:nb_frames=45
4036 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
4038 fade=in:0:25, fade=out:975:25
4042 Make first 5 frames yellow, then fade in from frame 5-24:
4044 fade=in:5:20:color=yellow
4048 Fade in alpha over first 25 frames of video:
4050 fade=in:0:25:alpha=1
4054 Make first 5.5 seconds black, then fade in for 0.5 seconds:
4056 fade=t=in:st=5.5:d=0.5
4063 Extract a single field from an interlaced image using stride
4064 arithmetic to avoid wasting CPU time. The output frames are marked as
4067 The filter accepts the following options:
4071 Specify whether to extract the top (if the value is @code{0} or
4072 @code{top}) or the bottom field (if the value is @code{1} or
4078 Field matching filter for inverse telecine. It is meant to reconstruct the
4079 progressive frames from a telecined stream. The filter does not drop duplicated
4080 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
4081 followed by a decimation filter such as @ref{decimate} in the filtergraph.
4083 The separation of the field matching and the decimation is notably motivated by
4084 the possibility of inserting a de-interlacing filter fallback between the two.
4085 If the source has mixed telecined and real interlaced content,
4086 @code{fieldmatch} will not be able to match fields for the interlaced parts.
4087 But these remaining combed frames will be marked as interlaced, and thus can be
4088 de-interlaced by a later filter such as @ref{yadif} before decimation.
4090 In addition to the various configuration options, @code{fieldmatch} can take an
4091 optional second stream, activated through the @option{ppsrc} option. If
4092 enabled, the frames reconstruction will be based on the fields and frames from
4093 this second stream. This allows the first input to be pre-processed in order to
4094 help the various algorithms of the filter, while keeping the output lossless
4095 (assuming the fields are matched properly). Typically, a field-aware denoiser,
4096 or brightness/contrast adjustments can help.
4098 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
4099 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
4100 which @code{fieldmatch} is based on. While the semantic and usage are very
4101 close, some behaviour and options names can differ.
4103 The filter accepts the following options:
4107 Specify the assumed field order of the input stream. Available values are:
4111 Auto detect parity (use FFmpeg's internal parity value).
4113 Assume bottom field first.
4115 Assume top field first.
4118 Note that it is sometimes recommended not to trust the parity announced by the
4121 Default value is @var{auto}.
4124 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
4125 sense that it won't risk creating jerkiness due to duplicate frames when
4126 possible, but if there are bad edits or blended fields it will end up
4127 outputting combed frames when a good match might actually exist. On the other
4128 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
4129 but will almost always find a good frame if there is one. The other values are
4130 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
4131 jerkiness and creating duplicate frames versus finding good matches in sections
4132 with bad edits, orphaned fields, blended fields, etc.
4134 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
4136 Available values are:
4140 2-way matching (p/c)
4142 2-way matching, and trying 3rd match if still combed (p/c + n)
4144 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
4146 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
4147 still combed (p/c + n + u/b)
4149 3-way matching (p/c/n)
4151 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
4152 detected as combed (p/c/n + u/b)
4155 The parenthesis at the end indicate the matches that would be used for that
4156 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
4159 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
4162 Default value is @var{pc_n}.
4165 Mark the main input stream as a pre-processed input, and enable the secondary
4166 input stream as the clean source to pick the fields from. See the filter
4167 introduction for more details. It is similar to the @option{clip2} feature from
4170 Default value is @code{0} (disabled).
4173 Set the field to match from. It is recommended to set this to the same value as
4174 @option{order} unless you experience matching failures with that setting. In
4175 certain circumstances changing the field that is used to match from can have a
4176 large impact on matching performance. Available values are:
4180 Automatic (same value as @option{order}).
4182 Match from the bottom field.
4184 Match from the top field.
4187 Default value is @var{auto}.
4190 Set whether or not chroma is included during the match comparisons. In most
4191 cases it is recommended to leave this enabled. You should set this to @code{0}
4192 only if your clip has bad chroma problems such as heavy rainbowing or other
4193 artifacts. Setting this to @code{0} could also be used to speed things up at
4194 the cost of some accuracy.
4196 Default value is @code{1}.
4200 These define an exclusion band which excludes the lines between @option{y0} and
4201 @option{y1} from being included in the field matching decision. An exclusion
4202 band can be used to ignore subtitles, a logo, or other things that may
4203 interfere with the matching. @option{y0} sets the starting scan line and
4204 @option{y1} sets the ending line; all lines in between @option{y0} and
4205 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
4206 @option{y0} and @option{y1} to the same value will disable the feature.
4207 @option{y0} and @option{y1} defaults to @code{0}.
4210 Set the scene change detection threshold as a percentage of maximum change on
4211 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
4212 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
4213 @option{scthresh} is @code{[0.0, 100.0]}.
4215 Default value is @code{12.0}.
4218 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
4219 account the combed scores of matches when deciding what match to use as the
4220 final match. Available values are:
4224 No final matching based on combed scores.
4226 Combed scores are only used when a scene change is detected.
4228 Use combed scores all the time.
4231 Default is @var{sc}.
4234 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
4235 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
4236 Available values are:
4240 No forced calculation.
4242 Force p/c/n calculations.
4244 Force p/c/n/u/b calculations.
4247 Default value is @var{none}.
4250 This is the area combing threshold used for combed frame detection. This
4251 essentially controls how "strong" or "visible" combing must be to be detected.
4252 Larger values mean combing must be more visible and smaller values mean combing
4253 can be less visible or strong and still be detected. Valid settings are from
4254 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
4255 be detected as combed). This is basically a pixel difference value. A good
4256 range is @code{[8, 12]}.
4258 Default value is @code{9}.
4261 Sets whether or not chroma is considered in the combed frame decision. Only
4262 disable this if your source has chroma problems (rainbowing, etc.) that are
4263 causing problems for the combed frame detection with chroma enabled. Actually,
4264 using @option{chroma}=@var{0} is usually more reliable, except for the case
4265 where there is chroma only combing in the source.
4267 Default value is @code{0}.
4271 Respectively set the x-axis and y-axis size of the window used during combed
4272 frame detection. This has to do with the size of the area in which
4273 @option{combpel} pixels are required to be detected as combed for a frame to be
4274 declared combed. See the @option{combpel} parameter description for more info.
4275 Possible values are any number that is a power of 2 starting at 4 and going up
4278 Default value is @code{16}.
4281 The number of combed pixels inside any of the @option{blocky} by
4282 @option{blockx} size blocks on the frame for the frame to be detected as
4283 combed. While @option{cthresh} controls how "visible" the combing must be, this
4284 setting controls "how much" combing there must be in any localized area (a
4285 window defined by the @option{blockx} and @option{blocky} settings) on the
4286 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
4287 which point no frames will ever be detected as combed). This setting is known
4288 as @option{MI} in TFM/VFM vocabulary.
4290 Default value is @code{80}.
4293 @anchor{p/c/n/u/b meaning}
4294 @subsection p/c/n/u/b meaning
4296 @subsubsection p/c/n
4298 We assume the following telecined stream:
4301 Top fields: 1 2 2 3 4
4302 Bottom fields: 1 2 3 4 4
4305 The numbers correspond to the progressive frame the fields relate to. Here, the
4306 first two frames are progressive, the 3rd and 4th are combed, and so on.
4308 When @code{fieldmatch} is configured to run a matching from bottom
4309 (@option{field}=@var{bottom}) this is how this input stream get transformed:
4314 B 1 2 3 4 4 <-- matching reference
4323 As a result of the field matching, we can see that some frames get duplicated.
4324 To perform a complete inverse telecine, you need to rely on a decimation filter
4325 after this operation. See for instance the @ref{decimate} filter.
4327 The same operation now matching from top fields (@option{field}=@var{top})
4332 T 1 2 2 3 4 <-- matching reference
4342 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
4343 basically, they refer to the frame and field of the opposite parity:
4346 @item @var{p} matches the field of the opposite parity in the previous frame
4347 @item @var{c} matches the field of the opposite parity in the current frame
4348 @item @var{n} matches the field of the opposite parity in the next frame
4353 The @var{u} and @var{b} matching are a bit special in the sense that they match
4354 from the opposite parity flag. In the following examples, we assume that we are
4355 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
4356 'x' is placed above and below each matched fields.
4358 With bottom matching (@option{field}=@var{bottom}):
4363 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4364 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4372 With top matching (@option{field}=@var{top}):
4377 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4378 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4386 @subsection Examples
4388 Simple IVTC of a top field first telecined stream:
4390 fieldmatch=order=tff:combmatch=none, decimate
4393 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
4395 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
4400 Transform the field order of the input video.
4402 This filter accepts the following options:
4407 Output field order. Valid values are @var{tff} for top field first or @var{bff}
4408 for bottom field first.
4411 Default value is @samp{tff}.
4413 Transformation is achieved by shifting the picture content up or down
4414 by one line, and filling the remaining line with appropriate picture content.
4415 This method is consistent with most broadcast field order converters.
4417 If the input video is not flagged as being interlaced, or it is already
4418 flagged as being of the required output field order then this filter does
4419 not alter the incoming video.
4421 This filter is very useful when converting to or from PAL DV material,
4422 which is bottom field first.
4426 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
4431 Buffer input images and send them when they are requested.
4433 This filter is mainly useful when auto-inserted by the libavfilter
4436 The filter does not take parameters.
4441 Convert the input video to one of the specified pixel formats.
4442 Libavfilter will try to pick one that is supported for the input to
4445 This filter accepts the following parameters:
4449 A '|'-separated list of pixel format names, for example
4450 "pix_fmts=yuv420p|monow|rgb24".
4454 @subsection Examples
4458 Convert the input video to the format @var{yuv420p}
4460 format=pix_fmts=yuv420p
4463 Convert the input video to any of the formats in the list
4465 format=pix_fmts=yuv420p|yuv444p|yuv410p
4472 Convert the video to specified constant frame rate by duplicating or dropping
4473 frames as necessary.
4475 This filter accepts the following named parameters:
4479 Desired output frame rate. The default is @code{25}.
4484 Possible values are:
4487 zero round towards 0
4491 round towards -infinity
4493 round towards +infinity
4497 The default is @code{near}.
4500 Assume the first PTS should be the given value, in seconds. This allows for
4501 padding/trimming at the start of stream. By default, no assumption is made
4502 about the first frame's expected PTS, so no padding or trimming is done.
4503 For example, this could be set to 0 to pad the beginning with duplicates of
4504 the first frame if a video stream starts after the audio stream or to trim any
4505 frames with a negative PTS.
4509 Alternatively, the options can be specified as a flat string:
4510 @var{fps}[:@var{round}].
4512 See also the @ref{setpts} filter.
4514 @subsection Examples
4518 A typical usage in order to set the fps to 25:
4524 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
4526 fps=fps=film:round=near
4532 Pack two different video streams into a stereoscopic video, setting proper
4533 metadata on supported codecs. The two views should have the same size and
4534 framerate and processing will stop when the shorter video ends. Please note
4535 that you may conveniently adjust view properties with the @ref{scale} and
4538 This filter accepts the following named parameters:
4542 Desired packing format. Supported values are:
4547 Views are next to each other (default).
4550 Views are on top of each other.
4553 Views are packed by line.
4556 Views are eacked by column.
4559 Views are temporally interleaved.
4565 Some examples follow:
4568 # Convert left and right views into a frame sequential video.
4569 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
4571 # Convert views into a side-by-side video with the same output resolution as the input.
4572 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
4577 Select one frame every N-th frame.
4579 This filter accepts the following option:
4582 Select frame after every @code{step} frames.
4583 Allowed values are positive integers higher than 0. Default value is @code{1}.
4589 Apply a frei0r effect to the input video.
4591 To enable compilation of this filter you need to install the frei0r
4592 header and configure FFmpeg with @code{--enable-frei0r}.
4594 This filter accepts the following options:
4599 The name to the frei0r effect to load. If the environment variable
4600 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
4601 directories specified by the colon separated list in @env{FREIOR_PATH},
4602 otherwise in the standard frei0r paths, which are in this order:
4603 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
4604 @file{/usr/lib/frei0r-1/}.
4607 A '|'-separated list of parameters to pass to the frei0r effect.
4611 A frei0r effect parameter can be a boolean (whose values are specified
4612 with "y" and "n"), a double, a color (specified by the syntax
4613 @var{R}/@var{G}/@var{B}, (@var{R}, @var{G}, and @var{B} being float
4614 numbers from 0.0 to 1.0) or by a color description specified in the "Color"
4615 section in the ffmpeg-utils manual), a position (specified by the syntax @var{X}/@var{Y},
4616 @var{X} and @var{Y} being float numbers) and a string.
4618 The number and kind of parameters depend on the loaded effect. If an
4619 effect parameter is not specified the default value is set.
4621 @subsection Examples
4625 Apply the distort0r effect, set the first two double parameters:
4627 frei0r=filter_name=distort0r:filter_params=0.5|0.01
4631 Apply the colordistance effect, take a color as first parameter:
4633 frei0r=colordistance:0.2/0.3/0.4
4634 frei0r=colordistance:violet
4635 frei0r=colordistance:0x112233
4639 Apply the perspective effect, specify the top left and top right image
4642 frei0r=perspective:0.2/0.2|0.8/0.2
4646 For more information see:
4647 @url{http://frei0r.dyne.org}
4651 The filter accepts the following options:
4655 Set the luminance expression.
4657 Set the chrominance blue expression.
4659 Set the chrominance red expression.
4661 Set the alpha expression.
4663 Set the red expression.
4665 Set the green expression.
4667 Set the blue expression.
4670 The colorspace is selected according to the specified options. If one
4671 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
4672 options is specified, the filter will automatically select a YCbCr
4673 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
4674 @option{blue_expr} options is specified, it will select an RGB
4677 If one of the chrominance expression is not defined, it falls back on the other
4678 one. If no alpha expression is specified it will evaluate to opaque value.
4679 If none of chrominance expressions are specified, they will evaluate
4680 to the luminance expression.
4682 The expressions can use the following variables and functions:
4686 The sequential number of the filtered frame, starting from @code{0}.
4690 The coordinates of the current sample.
4694 The width and height of the image.
4698 Width and height scale depending on the currently filtered plane. It is the
4699 ratio between the corresponding luma plane number of pixels and the current
4700 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4701 @code{0.5,0.5} for chroma planes.
4704 Time of the current frame, expressed in seconds.
4707 Return the value of the pixel at location (@var{x},@var{y}) of the current
4711 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
4715 Return the value of the pixel at location (@var{x},@var{y}) of the
4716 blue-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-difference chroma plane. Return 0 if there is no such plane.
4725 Return the value of the pixel at location (@var{x},@var{y}) of the
4726 red/green/blue component. Return 0 if there is no such component.
4729 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
4730 plane. Return 0 if there is no such plane.
4733 For functions, if @var{x} and @var{y} are outside the area, the value will be
4734 automatically clipped to the closer edge.
4736 @subsection Examples
4740 Flip the image horizontally:
4746 Generate a bidimensional sine wave, with angle @code{PI/3} and a
4747 wavelength of 100 pixels:
4749 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
4753 Generate a fancy enigmatic moving light:
4755 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
4759 Generate a quick emboss effect:
4761 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
4765 Modify RGB components depending on pixel position:
4767 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
4773 Fix the banding artifacts that are sometimes introduced into nearly flat
4774 regions by truncation to 8bit color depth.
4775 Interpolate the gradients that should go where the bands are, and
4778 This filter is designed for playback only. Do not use it prior to
4779 lossy compression, because compression tends to lose the dither and
4780 bring back the bands.
4782 This filter accepts the following options:
4787 The maximum amount by which the filter will change any one pixel. Also the
4788 threshold for detecting nearly flat regions. Acceptable values range from .51 to
4789 64, default value is 1.2, out-of-range values will be clipped to the valid
4793 The neighborhood to fit the gradient to. A larger radius makes for smoother
4794 gradients, but also prevents the filter from modifying the pixels near detailed
4795 regions. Acceptable values are 8-32, default value is 16, out-of-range values
4796 will be clipped to the valid range.
4800 Alternatively, the options can be specified as a flat string:
4801 @var{strength}[:@var{radius}]
4803 @subsection Examples
4807 Apply the filter with a @code{3.5} strength and radius of @code{8}:
4813 Specify radius, omitting the strength (which will fall-back to the default
4824 Apply a Hald CLUT to a video stream.
4826 First input is the video stream to process, and second one is the Hald CLUT.
4827 The Hald CLUT input can be a simple picture or a complete video stream.
4829 The filter accepts the following options:
4833 Force termination when the shortest input terminates. Default is @code{0}.
4835 Continue applying the last CLUT after the end of the stream. A value of
4836 @code{0} disable the filter after the last frame of the CLUT is reached.
4837 Default is @code{1}.
4840 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
4841 filters share the same internals).
4843 More information about the Hald CLUT can be found on Eskil Steenberg's website
4844 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
4846 @subsection Workflow examples
4848 @subsubsection Hald CLUT video stream
4850 Generate an identity Hald CLUT stream altered with various effects:
4852 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
4855 Note: make sure you use a lossless codec.
4857 Then use it with @code{haldclut} to apply it on some random stream:
4859 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
4862 The Hald CLUT will be applied to the 10 first seconds (duration of
4863 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
4864 to the remaining frames of the @code{mandelbrot} stream.
4866 @subsubsection Hald CLUT with preview
4868 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
4869 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
4870 biggest possible square starting at the top left of the picture. The remaining
4871 padding pixels (bottom or right) will be ignored. This area can be used to add
4872 a preview of the Hald CLUT.
4874 Typically, the following generated Hald CLUT will be supported by the
4875 @code{haldclut} filter:
4878 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
4879 pad=iw+320 [padded_clut];
4880 smptebars=s=320x256, split [a][b];
4881 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
4882 [main][b] overlay=W-320" -frames:v 1 clut.png
4885 It contains the original and a preview of the effect of the CLUT: SMPTE color
4886 bars are displayed on the right-top, and below the same color bars processed by
4889 Then, the effect of this Hald CLUT can be visualized with:
4891 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
4896 Flip the input video horizontally.
4898 For example to horizontally flip the input video with @command{ffmpeg}:
4900 ffmpeg -i in.avi -vf "hflip" out.avi
4904 This filter applies a global color histogram equalization on a
4907 It can be used to correct video that has a compressed range of pixel
4908 intensities. The filter redistributes the pixel intensities to
4909 equalize their distribution across the intensity range. It may be
4910 viewed as an "automatically adjusting contrast filter". This filter is
4911 useful only for correcting degraded or poorly captured source
4914 The filter accepts the following options:
4918 Determine the amount of equalization to be applied. As the strength
4919 is reduced, the distribution of pixel intensities more-and-more
4920 approaches that of the input frame. The value must be a float number
4921 in the range [0,1] and defaults to 0.200.
4924 Set the maximum intensity that can generated and scale the output
4925 values appropriately. The strength should be set as desired and then
4926 the intensity can be limited if needed to avoid washing-out. The value
4927 must be a float number in the range [0,1] and defaults to 0.210.
4930 Set the antibanding level. If enabled the filter will randomly vary
4931 the luminance of output pixels by a small amount to avoid banding of
4932 the histogram. Possible values are @code{none}, @code{weak} or
4933 @code{strong}. It defaults to @code{none}.
4938 Compute and draw a color distribution histogram for the input video.
4940 The computed histogram is a representation of distribution of color components
4943 The filter accepts the following options:
4949 It accepts the following values:
4952 standard histogram that display color components distribution in an image.
4953 Displays color graph for each color component. Shows distribution
4954 of the Y, U, V, A or R, G, B components, depending on input format,
4955 in current frame. Bellow each graph is color component scale meter.
4958 chroma values in vectorscope, if brighter more such chroma values are
4959 distributed in an image.
4960 Displays chroma values (U/V color placement) in two dimensional graph
4961 (which is called a vectorscope). It can be used to read of the hue and
4962 saturation of the current frame. At a same time it is a histogram.
4963 The whiter a pixel in the vectorscope, the more pixels of the input frame
4964 correspond to that pixel (that is the more pixels have this chroma value).
4965 The V component is displayed on the horizontal (X) axis, with the leftmost
4966 side being V = 0 and the rightmost side being V = 255.
4967 The U component is displayed on the vertical (Y) axis, with the top
4968 representing U = 0 and the bottom representing U = 255.
4970 The position of a white pixel in the graph corresponds to the chroma value
4971 of a pixel of the input clip. So the graph can be used to read of the
4972 hue (color flavor) and the saturation (the dominance of the hue in the color).
4973 As the hue of a color changes, it moves around the square. At the center of
4974 the square, the saturation is zero, which means that the corresponding pixel
4975 has no color. If you increase the amount of a specific color, while leaving
4976 the other colors unchanged, the saturation increases, and you move towards
4977 the edge of the square.
4980 chroma values in vectorscope, similar as @code{color} but actual chroma values
4984 per row/column color component graph. In row mode graph in the left side represents
4985 color component value 0 and right side represents value = 255. In column mode top
4986 side represents color component value = 0 and bottom side represents value = 255.
4988 Default value is @code{levels}.
4991 Set height of level in @code{levels}. Default value is @code{200}.
4992 Allowed range is [50, 2048].
4995 Set height of color scale in @code{levels}. Default value is @code{12}.
4996 Allowed range is [0, 40].
4999 Set step for @code{waveform} mode. Smaller values are useful to find out how much
5000 of same luminance values across input rows/columns are distributed.
5001 Default value is @code{10}. Allowed range is [1, 255].
5004 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
5005 Default is @code{row}.
5007 @item waveform_mirror
5008 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
5009 means mirrored. In mirrored mode, higher values will be represented on the left
5010 side for @code{row} mode and at the top for @code{column} mode. Default is
5011 @code{0} (unmirrored).
5014 Set display mode for @code{waveform} and @code{levels}.
5015 It accepts the following values:
5018 Display separate graph for the color components side by side in
5019 @code{row} waveform mode or one below other in @code{column} waveform mode
5020 for @code{waveform} histogram mode. For @code{levels} histogram mode
5021 per color component graphs are placed one bellow other.
5023 This display mode in @code{waveform} histogram mode makes it easy to spot
5024 color casts in the highlights and shadows of an image, by comparing the
5025 contours of the top and the bottom of each waveform.
5026 Since whites, grays, and blacks are characterized by
5027 exactly equal amounts of red, green, and blue, neutral areas of the
5028 picture should display three waveforms of roughly equal width/height.
5029 If not, the correction is easy to make by making adjustments to level the
5033 Presents information that's identical to that in the @code{parade}, except
5034 that the graphs representing color components are superimposed directly
5037 This display mode in @code{waveform} histogram mode can make it easier to spot
5038 the relative differences or similarities in overlapping areas of the color
5039 components that are supposed to be identical, such as neutral whites, grays,
5042 Default is @code{parade}.
5045 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
5046 Default is @code{linear}.
5049 @subsection Examples
5054 Calculate and draw histogram:
5056 ffplay -i input -vf histogram
5064 High precision/quality 3d denoise filter. This filter aims to reduce
5065 image noise producing smooth images and making still images really
5066 still. It should enhance compressibility.
5068 It accepts the following optional parameters:
5072 a non-negative float number which specifies spatial luma strength,
5075 @item chroma_spatial
5076 a non-negative float number which specifies spatial chroma strength,
5077 defaults to 3.0*@var{luma_spatial}/4.0
5080 a float number which specifies luma temporal strength, defaults to
5081 6.0*@var{luma_spatial}/4.0
5084 a float number which specifies chroma temporal strength, defaults to
5085 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
5090 Modify the hue and/or the saturation of the input.
5092 This filter accepts the following options:
5096 Specify the hue angle as a number of degrees. It accepts an expression,
5097 and defaults to "0".
5100 Specify the saturation in the [-10,10] range. It accepts an expression and
5104 Specify the hue angle as a number of radians. It accepts an
5105 expression, and defaults to "0".
5108 Specify the brightness in the [-10,10] range. It accepts an expression and
5112 @option{h} and @option{H} are mutually exclusive, and can't be
5113 specified at the same time.
5115 The @option{b}, @option{h}, @option{H} and @option{s} option values are
5116 expressions containing the following constants:
5120 frame count of the input frame starting from 0
5123 presentation timestamp of the input frame expressed in time base units
5126 frame rate of the input video, NAN if the input frame rate is unknown
5129 timestamp expressed in seconds, NAN if the input timestamp is unknown
5132 time base of the input video
5135 @subsection Examples
5139 Set the hue to 90 degrees and the saturation to 1.0:
5145 Same command but expressing the hue in radians:
5151 Rotate hue and make the saturation swing between 0
5152 and 2 over a period of 1 second:
5154 hue="H=2*PI*t: s=sin(2*PI*t)+1"
5158 Apply a 3 seconds saturation fade-in effect starting at 0:
5163 The general fade-in expression can be written as:
5165 hue="s=min(0\, max((t-START)/DURATION\, 1))"
5169 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
5171 hue="s=max(0\, min(1\, (8-t)/3))"
5174 The general fade-out expression can be written as:
5176 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
5181 @subsection Commands
5183 This filter supports the following commands:
5189 Modify the hue and/or the saturation and/or brightness of the input video.
5190 The command accepts the same syntax of the corresponding option.
5192 If the specified expression is not valid, it is kept at its current
5198 Detect video interlacing type.
5200 This filter tries to detect if the input is interlaced or progressive,
5201 top or bottom field first.
5203 The filter accepts the following options:
5207 Set interlacing threshold.
5209 Set progressive threshold.
5214 Deinterleave or interleave fields.
5216 This filter allows to process interlaced images fields without
5217 deinterlacing them. Deinterleaving splits the input frame into 2
5218 fields (so called half pictures). Odd lines are moved to the top
5219 half of the output image, even lines to the bottom half.
5220 You can process (filter) them independently and then re-interleave them.
5222 The filter accepts the following options:
5226 @item chroma_mode, c
5228 Available values for @var{luma_mode}, @var{chroma_mode} and
5229 @var{alpha_mode} are:
5235 @item deinterleave, d
5236 Deinterleave fields, placing one above the other.
5239 Interleave fields. Reverse the effect of deinterleaving.
5241 Default value is @code{none}.
5244 @item chroma_swap, cs
5245 @item alpha_swap, as
5246 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
5251 Simple interlacing filter from progressive contents. This interleaves upper (or
5252 lower) lines from odd frames with lower (or upper) lines from even frames,
5253 halving the frame rate and preserving image height.
5256 Original Original New Frame
5257 Frame 'j' Frame 'j+1' (tff)
5258 ========== =========== ==================
5259 Line 0 --------------------> Frame 'j' Line 0
5260 Line 1 Line 1 ----> Frame 'j+1' Line 1
5261 Line 2 ---------------------> Frame 'j' Line 2
5262 Line 3 Line 3 ----> Frame 'j+1' Line 3
5264 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
5267 It accepts the following optional parameters:
5271 determines whether the interlaced frame is taken from the even (tff - default)
5272 or odd (bff) lines of the progressive frame.
5275 Enable (default) or disable the vertical lowpass filter to avoid twitter
5276 interlacing and reduce moire patterns.
5281 Deinterlace input video by applying Donald Graft's adaptive kernel
5282 deinterling. Work on interlaced parts of a video to produce
5285 The description of the accepted parameters follows.
5289 Set the threshold which affects the filter's tolerance when
5290 determining if a pixel line must be processed. It must be an integer
5291 in the range [0,255] and defaults to 10. A value of 0 will result in
5292 applying the process on every pixels.
5295 Paint pixels exceeding the threshold value to white if set to 1.
5299 Set the fields order. Swap fields if set to 1, leave fields alone if
5303 Enable additional sharpening if set to 1. Default is 0.
5306 Enable twoway sharpening if set to 1. Default is 0.
5309 @subsection Examples
5313 Apply default values:
5315 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
5319 Enable additional sharpening:
5325 Paint processed pixels in white:
5334 Apply a 3D LUT to an input video.
5336 The filter accepts the following options:
5340 Set the 3D LUT file name.
5342 Currently supported formats:
5354 Select interpolation mode.
5356 Available values are:
5360 Use values from the nearest defined point.
5362 Interpolate values using the 8 points defining a cube.
5364 Interpolate values using a tetrahedron.
5368 @section lut, lutrgb, lutyuv
5370 Compute a look-up table for binding each pixel component input value
5371 to an output value, and apply it to input video.
5373 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
5374 to an RGB input video.
5376 These filters accept the following options:
5379 set first pixel component expression
5381 set second pixel component expression
5383 set third pixel component expression
5385 set fourth pixel component expression, corresponds to the alpha component
5388 set red component expression
5390 set green component expression
5392 set blue component expression
5394 alpha component expression
5397 set Y/luminance component expression
5399 set U/Cb component expression
5401 set V/Cr component expression
5404 Each of them specifies the expression to use for computing the lookup table for
5405 the corresponding pixel component values.
5407 The exact component associated to each of the @var{c*} options depends on the
5410 The @var{lut} filter requires either YUV or RGB pixel formats in input,
5411 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
5413 The expressions can contain the following constants and functions:
5418 the input width and height
5421 input value for the pixel component
5424 the input value clipped in the @var{minval}-@var{maxval} range
5427 maximum value for the pixel component
5430 minimum value for the pixel component
5433 the negated value for the pixel component value clipped in the
5434 @var{minval}-@var{maxval} range , it corresponds to the expression
5435 "maxval-clipval+minval"
5438 the computed value in @var{val} clipped in the
5439 @var{minval}-@var{maxval} range
5441 @item gammaval(gamma)
5442 the computed gamma correction value of the pixel component value
5443 clipped in the @var{minval}-@var{maxval} range, corresponds to the
5445 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
5449 All expressions default to "val".
5451 @subsection Examples
5457 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
5458 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
5461 The above is the same as:
5463 lutrgb="r=negval:g=negval:b=negval"
5464 lutyuv="y=negval:u=negval:v=negval"
5474 Remove chroma components, turns the video into a graytone image:
5476 lutyuv="u=128:v=128"
5480 Apply a luma burning effect:
5486 Remove green and blue components:
5492 Set a constant alpha channel value on input:
5494 format=rgba,lutrgb=a="maxval-minval/2"
5498 Correct luminance gamma by a 0.5 factor:
5500 lutyuv=y=gammaval(0.5)
5504 Discard least significant bits of luma:
5506 lutyuv=y='bitand(val, 128+64+32)'
5510 @section mergeplanes
5512 Merge color channel components from several video streams.
5514 The filter accepts up to 4 input streams, and merge selected input
5515 planes to the output video.
5517 This filter accepts the following options:
5520 Set input to output plane mapping. Default is @code{0}.
5522 The mappings is specified as a bitmap. It should be specified as a
5523 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
5524 mapping for the first plane of the output stream. 'A' sets the number of
5525 the input stream to use (from 0 to 3), and 'a' the plane number of the
5526 corresponding input to use (from 0 to 3). The rest of the mappings is
5527 similar, 'Bb' describes the mapping for the output stream second
5528 plane, 'Cc' describes the mapping for the output stream third plane and
5529 'Dd' describes the mapping for the output stream fourth plane.
5532 Set output pixel format. Default is @code{yuva444p}.
5535 @subsection Examples
5539 Merge three gray video streams of same width and height into single video stream:
5541 [a0][a1][a2]mergeplanes=0x001020:yuv444p
5545 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
5547 [a0][a1]mergeplanes=0x00010210:yuva444p
5551 Swap Y and A plane in yuva444p stream:
5553 format=yuva444p,mergeplanes=0x03010200:yuva444p
5557 Swap U and V plane in yuv420p stream:
5559 format=yuv420p,mergeplanes=0x000201:yuv420p
5563 Cast a rgb24 clip to yuv444p:
5565 format=rgb24,mergeplanes=0x000102:yuv444p
5571 Apply motion-compensation deinterlacing.
5573 It needs one field per frame as input and must thus be used together
5574 with yadif=1/3 or equivalent.
5576 This filter accepts the following options:
5579 Set the deinterlacing mode.
5581 It accepts one of the following values:
5586 use iterative motion estimation
5588 like @samp{slow}, but use multiple reference frames.
5590 Default value is @samp{fast}.
5593 Set the picture field parity assumed for the input video. It must be
5594 one of the following values:
5598 assume top field first
5600 assume bottom field first
5603 Default value is @samp{bff}.
5606 Set per-block quantization parameter (QP) used by the internal
5609 Higher values should result in a smoother motion vector field but less
5610 optimal individual vectors. Default value is 1.
5615 Apply an MPlayer filter to the input video.
5617 This filter provides a wrapper around some of the filters of
5620 This wrapper is considered experimental. Some of the wrapped filters
5621 may not work properly and we may drop support for them, as they will
5622 be implemented natively into FFmpeg. Thus you should avoid
5623 depending on them when writing portable scripts.
5625 The filter accepts the parameters:
5626 @var{filter_name}[:=]@var{filter_params}
5628 @var{filter_name} is the name of a supported MPlayer filter,
5629 @var{filter_params} is a string containing the parameters accepted by
5632 The list of the currently supported filters follows:
5643 The parameter syntax and behavior for the listed filters are the same
5644 of the corresponding MPlayer filters. For detailed instructions check
5645 the "VIDEO FILTERS" section in the MPlayer manual.
5647 @subsection Examples
5651 Adjust gamma, brightness, contrast:
5657 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
5661 Drop frames that do not differ greatly from the previous frame in
5662 order to reduce frame rate.
5664 The main use of this filter is for very-low-bitrate encoding
5665 (e.g. streaming over dialup modem), but it could in theory be used for
5666 fixing movies that were inverse-telecined incorrectly.
5668 A description of the accepted options follows.
5672 Set the maximum number of consecutive frames which can be dropped (if
5673 positive), or the minimum interval between dropped frames (if
5674 negative). If the value is 0, the frame is dropped unregarding the
5675 number of previous sequentially dropped frames.
5682 Set the dropping threshold values.
5684 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
5685 represent actual pixel value differences, so a threshold of 64
5686 corresponds to 1 unit of difference for each pixel, or the same spread
5687 out differently over the block.
5689 A frame is a candidate for dropping if no 8x8 blocks differ by more
5690 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
5691 meaning the whole image) differ by more than a threshold of @option{lo}.
5693 Default value for @option{hi} is 64*12, default value for @option{lo} is
5694 64*5, and default value for @option{frac} is 0.33.
5702 This filter accepts an integer in input, if non-zero it negates the
5703 alpha component (if available). The default value in input is 0.
5707 Force libavfilter not to use any of the specified pixel formats for the
5708 input to the next filter.
5710 This filter accepts the following parameters:
5714 A '|'-separated list of pixel format names, for example
5715 "pix_fmts=yuv420p|monow|rgb24".
5719 @subsection Examples
5723 Force libavfilter to use a format different from @var{yuv420p} for the
5724 input to the vflip filter:
5726 noformat=pix_fmts=yuv420p,vflip
5730 Convert the input video to any of the formats not contained in the list:
5732 noformat=yuv420p|yuv444p|yuv410p
5738 Add noise on video input frame.
5740 The filter accepts the following options:
5748 Set noise seed for specific pixel component or all pixel components in case
5749 of @var{all_seed}. Default value is @code{123457}.
5751 @item all_strength, alls
5752 @item c0_strength, c0s
5753 @item c1_strength, c1s
5754 @item c2_strength, c2s
5755 @item c3_strength, c3s
5756 Set noise strength for specific pixel component or all pixel components in case
5757 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
5759 @item all_flags, allf
5764 Set pixel component flags or set flags for all components if @var{all_flags}.
5765 Available values for component flags are:
5768 averaged temporal noise (smoother)
5770 mix random noise with a (semi)regular pattern
5772 temporal noise (noise pattern changes between frames)
5774 uniform noise (gaussian otherwise)
5778 @subsection Examples
5780 Add temporal and uniform noise to input video:
5782 noise=alls=20:allf=t+u
5787 Pass the video source unchanged to the output.
5791 Apply video transform using libopencv.
5793 To enable this filter install libopencv library and headers and
5794 configure FFmpeg with @code{--enable-libopencv}.
5796 This filter accepts the following parameters:
5801 The name of the libopencv filter to apply.
5804 The parameters to pass to the libopencv filter. If not specified the default
5809 Refer to the official libopencv documentation for more precise
5811 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
5813 Follows the list of supported libopencv filters.
5818 Dilate an image by using a specific structuring element.
5819 This filter corresponds to the libopencv function @code{cvDilate}.
5821 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
5823 @var{struct_el} represents a structuring element, and has the syntax:
5824 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
5826 @var{cols} and @var{rows} represent the number of columns and rows of
5827 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
5828 point, and @var{shape} the shape for the structuring element, and
5829 can be one of the values "rect", "cross", "ellipse", "custom".
5831 If the value for @var{shape} is "custom", it must be followed by a
5832 string of the form "=@var{filename}". The file with name
5833 @var{filename} is assumed to represent a binary image, with each
5834 printable character corresponding to a bright pixel. When a custom
5835 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
5836 or columns and rows of the read file are assumed instead.
5838 The default value for @var{struct_el} is "3x3+0x0/rect".
5840 @var{nb_iterations} specifies the number of times the transform is
5841 applied to the image, and defaults to 1.
5843 Follow some example:
5845 # use the default values
5848 # dilate using a structuring element with a 5x5 cross, iterate two times
5849 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
5851 # read the shape from the file diamond.shape, iterate two times
5852 # the file diamond.shape may contain a pattern of characters like this:
5858 # the specified cols and rows are ignored (but not the anchor point coordinates)
5859 ocv=dilate:0x0+2x2/custom=diamond.shape|2
5864 Erode an image by using a specific structuring element.
5865 This filter corresponds to the libopencv function @code{cvErode}.
5867 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
5868 with the same syntax and semantics as the @ref{dilate} filter.
5872 Smooth the input video.
5874 The filter takes the following parameters:
5875 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
5877 @var{type} is the type of smooth filter to apply, and can be one of
5878 the following values: "blur", "blur_no_scale", "median", "gaussian",
5879 "bilateral". The default value is "gaussian".
5881 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
5882 parameters whose meanings depend on smooth type. @var{param1} and
5883 @var{param2} accept integer positive values or 0, @var{param3} and
5884 @var{param4} accept float values.
5886 The default value for @var{param1} is 3, the default value for the
5887 other parameters is 0.
5889 These parameters correspond to the parameters assigned to the
5890 libopencv function @code{cvSmooth}.
5895 Overlay one video on top of another.
5897 It takes two inputs and one output, the first input is the "main"
5898 video on which the second input is overlayed.
5900 This filter accepts the following parameters:
5902 A description of the accepted options follows.
5907 Set the expression for the x and y coordinates of the overlayed video
5908 on the main video. Default value is "0" for both expressions. In case
5909 the expression is invalid, it is set to a huge value (meaning that the
5910 overlay will not be displayed within the output visible area).
5913 Set when the expressions for @option{x}, and @option{y} are evaluated.
5915 It accepts the following values:
5918 only evaluate expressions once during the filter initialization or
5919 when a command is processed
5922 evaluate expressions for each incoming frame
5925 Default value is @samp{frame}.
5928 If set to 1, force the output to terminate when the shortest input
5929 terminates. Default value is 0.
5932 Set the format for the output video.
5934 It accepts the following values:
5946 Default value is @samp{yuv420}.
5948 @item rgb @emph{(deprecated)}
5949 If set to 1, force the filter to accept inputs in the RGB
5950 color space. Default value is 0. This option is deprecated, use
5951 @option{format} instead.
5954 If set to 1, force the filter to draw the last overlay frame over the
5955 main input until the end of the stream. A value of 0 disables this
5956 behavior. Default value is 1.
5959 The @option{x}, and @option{y} expressions can contain the following
5965 main input width and height
5969 overlay input width and height
5973 the computed values for @var{x} and @var{y}. They are evaluated for
5978 horizontal and vertical chroma subsample values of the output
5979 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
5983 the number of input frame, starting from 0
5986 the position in the file of the input frame, NAN if unknown
5989 timestamp expressed in seconds, NAN if the input timestamp is unknown
5992 Note that the @var{n}, @var{pos}, @var{t} variables are available only
5993 when evaluation is done @emph{per frame}, and will evaluate to NAN
5994 when @option{eval} is set to @samp{init}.
5996 Be aware that frames are taken from each input video in timestamp
5997 order, hence, if their initial timestamps differ, it is a good idea
5998 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
5999 have them begin in the same zero timestamp, as it does the example for
6000 the @var{movie} filter.
6002 You can chain together more overlays but you should test the
6003 efficiency of such approach.
6005 @subsection Commands
6007 This filter supports the following commands:
6011 Modify the x and y of the overlay input.
6012 The command accepts the same syntax of the corresponding option.
6014 If the specified expression is not valid, it is kept at its current
6018 @subsection Examples
6022 Draw the overlay at 10 pixels from the bottom right corner of the main
6025 overlay=main_w-overlay_w-10:main_h-overlay_h-10
6028 Using named options the example above becomes:
6030 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
6034 Insert a transparent PNG logo in the bottom left corner of the input,
6035 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
6037 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
6041 Insert 2 different transparent PNG logos (second logo on bottom
6042 right corner) using the @command{ffmpeg} tool:
6044 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
6048 Add a transparent color layer on top of the main video, @code{WxH}
6049 must specify the size of the main input to the overlay filter:
6051 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
6055 Play an original video and a filtered version (here with the deshake
6056 filter) side by side using the @command{ffplay} tool:
6058 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
6061 The above command is the same as:
6063 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
6067 Make a sliding overlay appearing from the left to the right top part of the
6068 screen starting since time 2:
6070 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
6074 Compose output by putting two input videos side to side:
6076 ffmpeg -i left.avi -i right.avi -filter_complex "
6077 nullsrc=size=200x100 [background];
6078 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
6079 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
6080 [background][left] overlay=shortest=1 [background+left];
6081 [background+left][right] overlay=shortest=1:x=100 [left+right]
6086 Chain several overlays in cascade:
6088 nullsrc=s=200x200 [bg];
6089 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
6090 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
6091 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
6092 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
6093 [in3] null, [mid2] overlay=100:100 [out0]
6100 Apply Overcomplete Wavelet denoiser.
6102 The filter accepts the following options:
6108 Larger depth values will denoise lower frequency components more, but
6109 slow down filtering.
6111 Must be an int in the range 8-16, default is @code{8}.
6113 @item luma_strength, ls
6116 Must be a double value in the range 0-1000, default is @code{1.0}.
6118 @item chroma_strength, cs
6119 Set chroma strength.
6121 Must be a double value in the range 0-1000, default is @code{1.0}.
6126 Add paddings to the input image, and place the original input at the
6127 given coordinates @var{x}, @var{y}.
6129 This filter accepts the following parameters:
6134 Specify an expression for the size of the output image with the
6135 paddings added. If the value for @var{width} or @var{height} is 0, the
6136 corresponding input size is used for the output.
6138 The @var{width} expression can reference the value set by the
6139 @var{height} expression, and vice versa.
6141 The default value of @var{width} and @var{height} is 0.
6145 Specify an expression for the offsets where to place the input image
6146 in the padded area with respect to the top/left border of the output
6149 The @var{x} expression can reference the value set by the @var{y}
6150 expression, and vice versa.
6152 The default value of @var{x} and @var{y} is 0.
6155 Specify the color of the padded area. For the syntax of this option,
6156 check the "Color" section in the ffmpeg-utils manual.
6158 The default value of @var{color} is "black".
6161 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
6162 options are expressions containing the following constants:
6167 the input video width and height
6171 same as @var{in_w} and @var{in_h}
6175 the output width and height, that is the size of the padded area as
6176 specified by the @var{width} and @var{height} expressions
6180 same as @var{out_w} and @var{out_h}
6184 x and y offsets as specified by the @var{x} and @var{y}
6185 expressions, or NAN if not yet specified
6188 same as @var{iw} / @var{ih}
6191 input sample aspect ratio
6194 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
6198 horizontal and vertical chroma subsample values. For example for the
6199 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6202 @subsection Examples
6206 Add paddings with color "violet" to the input video. Output video
6207 size is 640x480, the top-left corner of the input video is placed at
6210 pad=640:480:0:40:violet
6213 The example above is equivalent to the following command:
6215 pad=width=640:height=480:x=0:y=40:color=violet
6219 Pad the input to get an output with dimensions increased by 3/2,
6220 and put the input video at the center of the padded area:
6222 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
6226 Pad the input to get a squared output with size equal to the maximum
6227 value between the input width and height, and put the input video at
6228 the center of the padded area:
6230 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
6234 Pad the input to get a final w/h ratio of 16:9:
6236 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
6240 In case of anamorphic video, in order to set the output display aspect
6241 correctly, it is necessary to use @var{sar} in the expression,
6242 according to the relation:
6244 (ih * X / ih) * sar = output_dar
6245 X = output_dar / sar
6248 Thus the previous example needs to be modified to:
6250 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
6254 Double output size and put the input video in the bottom-right
6255 corner of the output padded area:
6257 pad="2*iw:2*ih:ow-iw:oh-ih"
6261 @section perspective
6263 Correct perspective of video not recorded perpendicular to the screen.
6265 A description of the accepted parameters follows.
6276 Set coordinates expression for top left, top right, bottom left and bottom right corners.
6277 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
6279 The expressions can use the following variables:
6284 the width and height of video frame.
6288 Set interpolation for perspective correction.
6290 It accepts the following values:
6296 Default value is @samp{linear}.
6301 Delay interlaced video by one field time so that the field order changes.
6303 The intended use is to fix PAL movies that have been captured with the
6304 opposite field order to the film-to-video transfer.
6306 A description of the accepted parameters follows.
6312 It accepts the following values:
6315 Capture field order top-first, transfer bottom-first.
6316 Filter will delay the bottom field.
6319 Capture field order bottom-first, transfer top-first.
6320 Filter will delay the top field.
6323 Capture and transfer with the same field order. This mode only exists
6324 for the documentation of the other options to refer to, but if you
6325 actually select it, the filter will faithfully do nothing.
6328 Capture field order determined automatically by field flags, transfer
6330 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
6331 basis using field flags. If no field information is available,
6332 then this works just like @samp{u}.
6335 Capture unknown or varying, transfer opposite.
6336 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
6337 analyzing the images and selecting the alternative that produces best
6338 match between the fields.
6341 Capture top-first, transfer unknown or varying.
6342 Filter selects among @samp{t} and @samp{p} using image analysis.
6345 Capture bottom-first, transfer unknown or varying.
6346 Filter selects among @samp{b} and @samp{p} using image analysis.
6349 Capture determined by field flags, transfer unknown or varying.
6350 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
6351 image analysis. If no field information is available, then this works just
6352 like @samp{U}. This is the default mode.
6355 Both capture and transfer unknown or varying.
6356 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
6360 @section pixdesctest
6362 Pixel format descriptor test filter, mainly useful for internal
6363 testing. The output video should be equal to the input video.
6367 format=monow, pixdesctest
6370 can be used to test the monowhite pixel format descriptor definition.
6374 Enable the specified chain of postprocessing subfilters using libpostproc. This
6375 library should be automatically selected with a GPL build (@code{--enable-gpl}).
6376 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
6377 Each subfilter and some options have a short and a long name that can be used
6378 interchangeably, i.e. dr/dering are the same.
6380 The filters accept the following options:
6384 Set postprocessing subfilters string.
6387 All subfilters share common options to determine their scope:
6391 Honor the quality commands for this subfilter.
6394 Do chrominance filtering, too (default).
6397 Do luminance filtering only (no chrominance).
6400 Do chrominance filtering only (no luminance).
6403 These options can be appended after the subfilter name, separated by a '|'.
6405 Available subfilters are:
6408 @item hb/hdeblock[|difference[|flatness]]
6409 Horizontal deblocking filter
6412 Difference factor where higher values mean more deblocking (default: @code{32}).
6414 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6417 @item vb/vdeblock[|difference[|flatness]]
6418 Vertical deblocking filter
6421 Difference factor where higher values mean more deblocking (default: @code{32}).
6423 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6426 @item ha/hadeblock[|difference[|flatness]]
6427 Accurate horizontal deblocking filter
6430 Difference factor where higher values mean more deblocking (default: @code{32}).
6432 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6435 @item va/vadeblock[|difference[|flatness]]
6436 Accurate vertical deblocking filter
6439 Difference factor where higher values mean more deblocking (default: @code{32}).
6441 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6445 The horizontal and vertical deblocking filters share the difference and
6446 flatness values so you cannot set different horizontal and vertical
6451 Experimental horizontal deblocking filter
6454 Experimental vertical deblocking filter
6459 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
6462 larger -> stronger filtering
6464 larger -> stronger filtering
6466 larger -> stronger filtering
6469 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
6472 Stretch luminance to @code{0-255}.
6475 @item lb/linblenddeint
6476 Linear blend deinterlacing filter that deinterlaces the given block by
6477 filtering all lines with a @code{(1 2 1)} filter.
6479 @item li/linipoldeint
6480 Linear interpolating deinterlacing filter that deinterlaces the given block by
6481 linearly interpolating every second line.
6483 @item ci/cubicipoldeint
6484 Cubic interpolating deinterlacing filter deinterlaces the given block by
6485 cubically interpolating every second line.
6487 @item md/mediandeint
6488 Median deinterlacing filter that deinterlaces the given block by applying a
6489 median filter to every second line.
6491 @item fd/ffmpegdeint
6492 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
6493 second line with a @code{(-1 4 2 4 -1)} filter.
6496 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
6497 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
6499 @item fq/forceQuant[|quantizer]
6500 Overrides the quantizer table from the input with the constant quantizer you
6508 Default pp filter combination (@code{hb|a,vb|a,dr|a})
6511 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
6514 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
6517 @subsection Examples
6521 Apply horizontal and vertical deblocking, deringing and automatic
6522 brightness/contrast:
6528 Apply default filters without brightness/contrast correction:
6534 Apply default filters and temporal denoiser:
6536 pp=default/tmpnoise|1|2|3
6540 Apply deblocking on luminance only, and switch vertical deblocking on or off
6541 automatically depending on available CPU time:
6549 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
6550 Ratio) between two input videos.
6552 This filter takes in input two input videos, the first input is
6553 considered the "main" source and is passed unchanged to the
6554 output. The second input is used as a "reference" video for computing
6557 Both video inputs must have the same resolution and pixel format for
6558 this filter to work correctly. Also it assumes that both inputs
6559 have the same number of frames, which are compared one by one.
6561 The obtained average PSNR is printed through the logging system.
6563 The filter stores the accumulated MSE (mean squared error) of each
6564 frame, and at the end of the processing it is averaged across all frames
6565 equally, and the following formula is applied to obtain the PSNR:
6568 PSNR = 10*log10(MAX^2/MSE)
6571 Where MAX is the average of the maximum values of each component of the
6574 The description of the accepted parameters follows.
6578 If specified the filter will use the named file to save the PSNR of
6579 each individual frame.
6582 The file printed if @var{stats_file} is selected, contains a sequence of
6583 key/value pairs of the form @var{key}:@var{value} for each compared
6586 A description of each shown parameter follows:
6590 sequential number of the input frame, starting from 1
6593 Mean Square Error pixel-by-pixel average difference of the compared
6594 frames, averaged over all the image components.
6596 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
6597 Mean Square Error pixel-by-pixel average difference of the compared
6598 frames for the component specified by the suffix.
6600 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
6601 Peak Signal to Noise ratio of the compared frames for the component
6602 specified by the suffix.
6607 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
6608 [main][ref] psnr="stats_file=stats.log" [out]
6611 On this example the input file being processed is compared with the
6612 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
6613 is stored in @file{stats.log}.
6617 Pulldown reversal (inverse telecine) filter, capable of handling mixed
6618 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
6621 The pullup filter is designed to take advantage of future context in making
6622 its decisions. This filter is stateless in the sense that it does not lock
6623 onto a pattern to follow, but it instead looks forward to the following
6624 fields in order to identify matches and rebuild progressive frames.
6626 To produce content with an even framerate, insert the fps filter after
6627 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
6628 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
6630 The filter accepts the following options:
6637 These options set the amount of "junk" to ignore at the left, right, top, and
6638 bottom of the image, respectively. Left and right are in units of 8 pixels,
6639 while top and bottom are in units of 2 lines.
6640 The default is 8 pixels on each side.
6643 Set the strict breaks. Setting this option to 1 will reduce the chances of
6644 filter generating an occasional mismatched frame, but it may also cause an
6645 excessive number of frames to be dropped during high motion sequences.
6646 Conversely, setting it to -1 will make filter match fields more easily.
6647 This may help processing of video where there is slight blurring between
6648 the fields, but may also cause there to be interlaced frames in the output.
6649 Default value is @code{0}.
6652 Set the metric plane to use. It accepts the following values:
6658 Use chroma blue plane.
6661 Use chroma red plane.
6664 This option may be set to use chroma plane instead of the default luma plane
6665 for doing filter's computations. This may improve accuracy on very clean
6666 source material, but more likely will decrease accuracy, especially if there
6667 is chroma noise (rainbow effect) or any grayscale video.
6668 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
6669 load and make pullup usable in realtime on slow machines.
6672 For best results (without duplicated frames in the output file) it is
6673 necessary to change the output frame rate. For example, to inverse
6674 telecine NTSC input:
6676 ffmpeg -i input -vf pullup -r 24000/1001 ...
6681 Suppress a TV station logo, using an image file to determine which
6682 pixels comprise the logo. It works by filling in the pixels that
6683 comprise the logo with neighboring pixels.
6685 The filter accepts the following options:
6689 Set the filter bitmap file, which can be any image format supported by
6690 libavformat. The width and height of the image file must match those of the
6691 video stream being processed.
6694 Pixels in the provided bitmap image with a value of zero are not
6695 considered part of the logo, non-zero pixels are considered part of
6696 the logo. If you use white (255) for the logo and black (0) for the
6697 rest, you will be safe. For making the filter bitmap, it is
6698 recommended to take a screen capture of a black frame with the logo
6699 visible, and then using a threshold filter followed by the erode
6700 filter once or twice.
6702 If needed, little splotches can be fixed manually. Remember that if
6703 logo pixels are not covered, the filter quality will be much
6704 reduced. Marking too many pixels as part of the logo does not hurt as
6705 much, but it will increase the amount of blurring needed to cover over
6706 the image and will destroy more information than necessary, and extra
6707 pixels will slow things down on a large logo.
6711 Rotate video by an arbitrary angle expressed in radians.
6713 The filter accepts the following options:
6715 A description of the optional parameters follows.
6718 Set an expression for the angle by which to rotate the input video
6719 clockwise, expressed as a number of radians. A negative value will
6720 result in a counter-clockwise rotation. By default it is set to "0".
6722 This expression is evaluated for each frame.
6725 Set the output width expression, default value is "iw".
6726 This expression is evaluated just once during configuration.
6729 Set the output height expression, default value is "ih".
6730 This expression is evaluated just once during configuration.
6733 Enable bilinear interpolation if set to 1, a value of 0 disables
6734 it. Default value is 1.
6737 Set the color used to fill the output area not covered by the rotated
6738 image. For the generalsyntax of this option, check the "Color" section in the
6739 ffmpeg-utils manual. If the special value "none" is selected then no
6740 background is printed (useful for example if the background is never shown).
6742 Default value is "black".
6745 The expressions for the angle and the output size can contain the
6746 following constants and functions:
6750 sequential number of the input frame, starting from 0. It is always NAN
6751 before the first frame is filtered.
6754 time in seconds of the input frame, it is set to 0 when the filter is
6755 configured. It is always NAN before the first frame is filtered.
6759 horizontal and vertical chroma subsample values. For example for the
6760 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6764 the input video width and heigth
6768 the output width and heigth, that is the size of the padded area as
6769 specified by the @var{width} and @var{height} expressions
6773 the minimal width/height required for completely containing the input
6774 video rotated by @var{a} radians.
6776 These are only available when computing the @option{out_w} and
6777 @option{out_h} expressions.
6780 @subsection Examples
6784 Rotate the input by PI/6 radians clockwise:
6790 Rotate the input by PI/6 radians counter-clockwise:
6796 Rotate the input by 45 degrees clockwise:
6802 Apply a constant rotation with period T, starting from an angle of PI/3:
6804 rotate=PI/3+2*PI*t/T
6808 Make the input video rotation oscillating with a period of T
6809 seconds and an amplitude of A radians:
6811 rotate=A*sin(2*PI/T*t)
6815 Rotate the video, output size is choosen so that the whole rotating
6816 input video is always completely contained in the output:
6818 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
6822 Rotate the video, reduce the output size so that no background is ever
6825 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
6829 @subsection Commands
6831 The filter supports the following commands:
6835 Set the angle expression.
6836 The command accepts the same syntax of the corresponding option.
6838 If the specified expression is not valid, it is kept at its current
6844 Apply Shape Adaptive Blur.
6846 The filter accepts the following options:
6849 @item luma_radius, lr
6850 Set luma blur filter strength, must be a value in range 0.1-4.0, default
6851 value is 1.0. A greater value will result in a more blurred image, and
6852 in slower processing.
6854 @item luma_pre_filter_radius, lpfr
6855 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
6858 @item luma_strength, ls
6859 Set luma maximum difference between pixels to still be considered, must
6860 be a value in the 0.1-100.0 range, default value is 1.0.
6862 @item chroma_radius, cr
6863 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
6864 greater value will result in a more blurred image, and in slower
6867 @item chroma_pre_filter_radius, cpfr
6868 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
6870 @item chroma_strength, cs
6871 Set chroma maximum difference between pixels to still be considered,
6872 must be a value in the 0.1-100.0 range.
6875 Each chroma option value, if not explicitly specified, is set to the
6876 corresponding luma option value.
6881 Scale (resize) the input video, using the libswscale library.
6883 The scale filter forces the output display aspect ratio to be the same
6884 of the input, by changing the output sample aspect ratio.
6886 If the input image format is different from the format requested by
6887 the next filter, the scale filter will convert the input to the
6891 The filter accepts the following options, or any of the options
6892 supported by the libswscale scaler.
6894 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
6895 the complete list of scaler options.
6900 Set the output video dimension expression. Default value is the input
6903 If the value is 0, the input width is used for the output.
6905 If one of the values is -1, the scale filter will use a value that
6906 maintains the aspect ratio of the input image, calculated from the
6907 other specified dimension. If both of them are -1, the input size is
6910 If one of the values is -n with n > 1, the scale filter will also use a value
6911 that maintains the aspect ratio of the input image, calculated from the other
6912 specified dimension. After that it will, however, make sure that the calculated
6913 dimension is divisible by n and adjust the value if necessary.
6915 See below for the list of accepted constants for use in the dimension
6919 Set the interlacing mode. It accepts the following values:
6923 Force interlaced aware scaling.
6926 Do not apply interlaced scaling.
6929 Select interlaced aware scaling depending on whether the source frames
6930 are flagged as interlaced or not.
6933 Default value is @samp{0}.
6936 Set libswscale scaling flags. See
6937 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
6938 complete list of values. If not explictly specified the filter applies
6942 Set the video size. For the syntax of this option, check the "Video size"
6943 section in the ffmpeg-utils manual.
6945 @item in_color_matrix
6946 @item out_color_matrix
6947 Set in/output YCbCr color space type.
6949 This allows the autodetected value to be overridden as well as allows forcing
6950 a specific value used for the output and encoder.
6952 If not specified, the color space type depends on the pixel format.
6958 Choose automatically.
6961 Format conforming to International Telecommunication Union (ITU)
6962 Recommendation BT.709.
6965 Set color space conforming to the United States Federal Communications
6966 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
6969 Set color space conforming to:
6973 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
6976 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
6979 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
6984 Set color space conforming to SMPTE ST 240:1999.
6989 Set in/output YCbCr sample range.
6991 This allows the autodetected value to be overridden as well as allows forcing
6992 a specific value used for the output and encoder. If not specified, the
6993 range depends on the pixel format. Possible values:
6997 Choose automatically.
7000 Set full range (0-255 in case of 8-bit luma).
7003 Set "MPEG" range (16-235 in case of 8-bit luma).
7006 @item force_original_aspect_ratio
7007 Enable decreasing or increasing output video width or height if necessary to
7008 keep the original aspect ratio. Possible values:
7012 Scale the video as specified and disable this feature.
7015 The output video dimensions will automatically be decreased if needed.
7018 The output video dimensions will automatically be increased if needed.
7022 One useful instance of this option is that when you know a specific device's
7023 maximum allowed resolution, you can use this to limit the output video to
7024 that, while retaining the aspect ratio. For example, device A allows
7025 1280x720 playback, and your video is 1920x800. Using this option (set it to
7026 decrease) and specifying 1280x720 to the command line makes the output
7029 Please note that this is a different thing than specifying -1 for @option{w}
7030 or @option{h}, you still need to specify the output resolution for this option
7035 The values of the @option{w} and @option{h} options are expressions
7036 containing the following constants:
7041 the input width and height
7045 same as @var{in_w} and @var{in_h}
7049 the output (scaled) width and height
7053 same as @var{out_w} and @var{out_h}
7056 same as @var{iw} / @var{ih}
7059 input sample aspect ratio
7062 input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
7066 horizontal and vertical input chroma subsample values. For example for the
7067 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7071 horizontal and vertical output chroma subsample values. For example for the
7072 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7075 @subsection Examples
7079 Scale the input video to a size of 200x100:
7084 This is equivalent to:
7095 Specify a size abbreviation for the output size:
7100 which can also be written as:
7106 Scale the input to 2x:
7112 The above is the same as:
7118 Scale the input to 2x with forced interlaced scaling:
7120 scale=2*iw:2*ih:interl=1
7124 Scale the input to half size:
7130 Increase the width, and set the height to the same size:
7136 Seek for Greek harmony:
7143 Increase the height, and set the width to 3/2 of the height:
7145 scale=w=3/2*oh:h=3/5*ih
7149 Increase the size, but make the size a multiple of the chroma
7152 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
7156 Increase the width to a maximum of 500 pixels, keep the same input
7159 scale=w='min(500\, iw*3/2):h=-1'
7163 @section separatefields
7165 The @code{separatefields} takes a frame-based video input and splits
7166 each frame into its components fields, producing a new half height clip
7167 with twice the frame rate and twice the frame count.
7169 This filter use field-dominance information in frame to decide which
7170 of each pair of fields to place first in the output.
7171 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
7173 @section setdar, setsar
7175 The @code{setdar} filter sets the Display Aspect Ratio for the filter
7178 This is done by changing the specified Sample (aka Pixel) Aspect
7179 Ratio, according to the following equation:
7181 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
7184 Keep in mind that the @code{setdar} filter does not modify the pixel
7185 dimensions of the video frame. Also the display aspect ratio set by
7186 this filter may be changed by later filters in the filterchain,
7187 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
7190 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
7191 the filter output video.
7193 Note that as a consequence of the application of this filter, the
7194 output display aspect ratio will change according to the equation
7197 Keep in mind that the sample aspect ratio set by the @code{setsar}
7198 filter may be changed by later filters in the filterchain, e.g. if
7199 another "setsar" or a "setdar" filter is applied.
7201 The filters accept the following options:
7204 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
7205 Set the aspect ratio used by the filter.
7207 The parameter can be a floating point number string, an expression, or
7208 a string of the form @var{num}:@var{den}, where @var{num} and
7209 @var{den} are the numerator and denominator of the aspect ratio. If
7210 the parameter is not specified, it is assumed the value "0".
7211 In case the form "@var{num}:@var{den}" is used, the @code{:} character
7215 Set the maximum integer value to use for expressing numerator and
7216 denominator when reducing the expressed aspect ratio to a rational.
7217 Default value is @code{100}.
7221 The parameter @var{sar} is an expression containing
7222 the following constants:
7226 the corresponding mathematical approximated values for e
7227 (euler number), pi (greek PI), phi (golden ratio)
7230 the input width and height
7233 same as @var{w} / @var{h}
7236 input sample aspect ratio
7239 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
7242 horizontal and vertical chroma subsample values. For example for the
7243 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
7246 @subsection Examples
7251 To change the display aspect ratio to 16:9, specify one of the following:
7259 To change the sample aspect ratio to 10:11, specify:
7265 To set a display aspect ratio of 16:9, and specify a maximum integer value of
7266 1000 in the aspect ratio reduction, use the command:
7268 setdar=ratio=16/9:max=1000
7276 Force field for the output video frame.
7278 The @code{setfield} filter marks the interlace type field for the
7279 output frames. It does not change the input frame, but only sets the
7280 corresponding property, which affects how the frame is treated by
7281 following filters (e.g. @code{fieldorder} or @code{yadif}).
7283 The filter accepts the following options:
7288 Available values are:
7292 Keep the same field property.
7295 Mark the frame as bottom-field-first.
7298 Mark the frame as top-field-first.
7301 Mark the frame as progressive.
7307 Show a line containing various information for each input video frame.
7308 The input video is not modified.
7310 The shown line contains a sequence of key/value pairs of the form
7311 @var{key}:@var{value}.
7313 A description of each shown parameter follows:
7317 sequential number of the input frame, starting from 0
7320 Presentation TimeStamp of the input frame, expressed as a number of
7321 time base units. The time base unit depends on the filter input pad.
7324 Presentation TimeStamp of the input frame, expressed as a number of
7328 position of the frame in the input stream, -1 if this information in
7329 unavailable and/or meaningless (for example in case of synthetic video)
7335 sample aspect ratio of the input frame, expressed in the form
7339 size of the input frame. For the syntax of this option, check the "Video size"
7340 section in the ffmpeg-utils manual.
7343 interlaced mode ("P" for "progressive", "T" for top field first, "B"
7344 for bottom field first)
7347 1 if the frame is a key frame, 0 otherwise
7350 picture type of the input frame ("I" for an I-frame, "P" for a
7351 P-frame, "B" for a B-frame, "?" for unknown type).
7352 Check also the documentation of the @code{AVPictureType} enum and of
7353 the @code{av_get_picture_type_char} function defined in
7354 @file{libavutil/avutil.h}.
7357 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
7359 @item plane_checksum
7360 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
7361 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
7367 Blur the input video without impacting the outlines.
7369 The filter accepts the following options:
7372 @item luma_radius, lr
7373 Set the luma radius. The option value must be a float number in
7374 the range [0.1,5.0] that specifies the variance of the gaussian filter
7375 used to blur the image (slower if larger). Default value is 1.0.
7377 @item luma_strength, ls
7378 Set the luma strength. The option value must be a float number
7379 in the range [-1.0,1.0] that configures the blurring. A value included
7380 in [0.0,1.0] will blur the image whereas a value included in
7381 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7383 @item luma_threshold, lt
7384 Set the luma threshold used as a coefficient to determine
7385 whether a pixel should be blurred or not. The option value must be an
7386 integer in the range [-30,30]. A value of 0 will filter all the image,
7387 a value included in [0,30] will filter flat areas and a value included
7388 in [-30,0] will filter edges. Default value is 0.
7390 @item chroma_radius, cr
7391 Set the chroma radius. The option value must be a float number in
7392 the range [0.1,5.0] that specifies the variance of the gaussian filter
7393 used to blur the image (slower if larger). Default value is 1.0.
7395 @item chroma_strength, cs
7396 Set the chroma strength. The option value must be a float number
7397 in the range [-1.0,1.0] that configures the blurring. A value included
7398 in [0.0,1.0] will blur the image whereas a value included in
7399 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7401 @item chroma_threshold, ct
7402 Set the chroma threshold used as a coefficient to determine
7403 whether a pixel should be blurred or not. The option value must be an
7404 integer in the range [-30,30]. A value of 0 will filter all the image,
7405 a value included in [0,30] will filter flat areas and a value included
7406 in [-30,0] will filter edges. Default value is 0.
7409 If a chroma option is not explicitly set, the corresponding luma value
7414 Convert between different stereoscopic image formats.
7416 The filters accept the following options:
7420 Set stereoscopic image format of input.
7422 Available values for input image formats are:
7425 side by side parallel (left eye left, right eye right)
7428 side by side crosseye (right eye left, left eye right)
7431 side by side parallel with half width resolution
7432 (left eye left, right eye right)
7435 side by side crosseye with half width resolution
7436 (right eye left, left eye right)
7439 above-below (left eye above, right eye below)
7442 above-below (right eye above, left eye below)
7445 above-below with half height resolution
7446 (left eye above, right eye below)
7449 above-below with half height resolution
7450 (right eye above, left eye below)
7453 alternating frames (left eye first, right eye second)
7456 alternating frames (right eye first, left eye second)
7458 Default value is @samp{sbsl}.
7462 Set stereoscopic image format of output.
7464 Available values for output image formats are all the input formats as well as:
7467 anaglyph red/blue gray
7468 (red filter on left eye, blue filter on right eye)
7471 anaglyph red/green gray
7472 (red filter on left eye, green filter on right eye)
7475 anaglyph red/cyan gray
7476 (red filter on left eye, cyan filter on right eye)
7479 anaglyph red/cyan half colored
7480 (red filter on left eye, cyan filter on right eye)
7483 anaglyph red/cyan color
7484 (red filter on left eye, cyan filter on right eye)
7487 anaglyph red/cyan color optimized with the least squares projection of dubois
7488 (red filter on left eye, cyan filter on right eye)
7491 anaglyph green/magenta gray
7492 (green filter on left eye, magenta filter on right eye)
7495 anaglyph green/magenta half colored
7496 (green filter on left eye, magenta filter on right eye)
7499 anaglyph green/magenta colored
7500 (green filter on left eye, magenta filter on right eye)
7503 anaglyph green/magenta color optimized with the least squares projection of dubois
7504 (green filter on left eye, magenta filter on right eye)
7507 anaglyph yellow/blue gray
7508 (yellow filter on left eye, blue filter on right eye)
7511 anaglyph yellow/blue half colored
7512 (yellow filter on left eye, blue filter on right eye)
7515 anaglyph yellow/blue colored
7516 (yellow filter on left eye, blue filter on right eye)
7519 anaglyph yellow/blue color optimized with the least squares projection of dubois
7520 (yellow filter on left eye, blue filter on right eye)
7523 interleaved rows (left eye has top row, right eye starts on next row)
7526 interleaved rows (right eye has top row, left eye starts on next row)
7529 mono output (left eye only)
7532 mono output (right eye only)
7535 Default value is @samp{arcd}.
7538 @subsection Examples
7542 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
7548 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
7556 Apply a simple postprocessing filter that compresses and decompresses the image
7557 at several (or - in the case of @option{quality} level @code{6} - all) shifts
7558 and average the results.
7560 The filter accepts the following options:
7564 Set quality. This option defines the number of levels for averaging. It accepts
7565 an integer in the range 0-6. If set to @code{0}, the filter will have no
7566 effect. A value of @code{6} means the higher quality. For each increment of
7567 that value the speed drops by a factor of approximately 2. Default value is
7571 Force a constant quantization parameter. If not set, the filter will use the QP
7572 from the video stream (if available).
7575 Set thresholding mode. Available modes are:
7579 Set hard thresholding (default).
7581 Set soft thresholding (better de-ringing effect, but likely blurrier).
7585 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
7586 option may cause flicker since the B-Frames have often larger QP. Default is
7587 @code{0} (not enabled).
7593 Draw subtitles on top of input video using the libass library.
7595 To enable compilation of this filter you need to configure FFmpeg with
7596 @code{--enable-libass}. This filter also requires a build with libavcodec and
7597 libavformat to convert the passed subtitles file to ASS (Advanced Substation
7598 Alpha) subtitles format.
7600 The filter accepts the following options:
7604 Set the filename of the subtitle file to read. It must be specified.
7607 Specify the size of the original video, the video for which the ASS file
7608 was composed. For the syntax of this option, check the "Video size" section in
7609 the ffmpeg-utils manual. Due to a misdesign in ASS aspect ratio arithmetic,
7610 this is necessary to correctly scale the fonts if the aspect ratio has been
7614 Set subtitles input character encoding. @code{subtitles} filter only. Only
7615 useful if not UTF-8.
7618 If the first key is not specified, it is assumed that the first value
7619 specifies the @option{filename}.
7621 For example, to render the file @file{sub.srt} on top of the input
7622 video, use the command:
7627 which is equivalent to:
7629 subtitles=filename=sub.srt
7634 Scale the input by 2x and smooth using the Super2xSaI (Scale and
7635 Interpolate) pixel art scaling algorithm.
7637 Useful for enlarging pixel art images without reducing sharpness.
7644 Apply telecine process to the video.
7646 This filter accepts the following options:
7655 The default value is @code{top}.
7659 A string of numbers representing the pulldown pattern you wish to apply.
7660 The default value is @code{23}.
7664 Some typical patterns:
7669 24p: 2332 (preferred)
7676 24p: 222222222223 ("Euro pulldown")
7682 Select the most representative frame in a given sequence of consecutive frames.
7684 The filter accepts the following options:
7688 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
7689 will pick one of them, and then handle the next batch of @var{n} frames until
7690 the end. Default is @code{100}.
7693 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
7694 value will result in a higher memory usage, so a high value is not recommended.
7696 @subsection Examples
7700 Extract one picture each 50 frames:
7706 Complete example of a thumbnail creation with @command{ffmpeg}:
7708 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
7714 Tile several successive frames together.
7716 The filter accepts the following options:
7721 Set the grid size (i.e. the number of lines and columns). For the syntax of
7722 this option, check the "Video size" section in the ffmpeg-utils manual.
7725 Set the maximum number of frames to render in the given area. It must be less
7726 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
7727 the area will be used.
7730 Set the outer border margin in pixels.
7733 Set the inner border thickness (i.e. the number of pixels between frames). For
7734 more advanced padding options (such as having different values for the edges),
7735 refer to the pad video filter.
7738 Specify the color of the unused areaFor the syntax of this option, check the
7739 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
7743 @subsection Examples
7747 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
7749 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
7751 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
7752 duplicating each output frame to accomodate the originally detected frame
7756 Display @code{5} pictures in an area of @code{3x2} frames,
7757 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
7758 mixed flat and named options:
7760 tile=3x2:nb_frames=5:padding=7:margin=2
7766 Perform various types of temporal field interlacing.
7768 Frames are counted starting from 1, so the first input frame is
7771 The filter accepts the following options:
7776 Specify the mode of the interlacing. This option can also be specified
7777 as a value alone. See below for a list of values for this option.
7779 Available values are:
7783 Move odd frames into the upper field, even into the lower field,
7784 generating a double height frame at half frame rate.
7787 Only output even frames, odd frames are dropped, generating a frame with
7788 unchanged height at half frame rate.
7791 Only output odd frames, even frames are dropped, generating a frame with
7792 unchanged height at half frame rate.
7795 Expand each frame to full height, but pad alternate lines with black,
7796 generating a frame with double height at the same input frame rate.
7798 @item interleave_top, 4
7799 Interleave the upper field from odd frames with the lower field from
7800 even frames, generating a frame with unchanged height at half frame rate.
7802 @item interleave_bottom, 5
7803 Interleave the lower field from odd frames with the upper field from
7804 even frames, generating a frame with unchanged height at half frame rate.
7806 @item interlacex2, 6
7807 Double frame rate with unchanged height. Frames are inserted each
7808 containing the second temporal field from the previous input frame and
7809 the first temporal field from the next input frame. This mode relies on
7810 the top_field_first flag. Useful for interlaced video displays with no
7811 field synchronisation.
7814 Numeric values are deprecated but are accepted for backward
7815 compatibility reasons.
7817 Default mode is @code{merge}.
7820 Specify flags influencing the filter process.
7822 Available value for @var{flags} is:
7825 @item low_pass_filter, vlfp
7826 Enable vertical low-pass filtering in the filter.
7827 Vertical low-pass filtering is required when creating an interlaced
7828 destination from a progressive source which contains high-frequency
7829 vertical detail. Filtering will reduce interlace 'twitter' and Moire
7832 Vertical low-pass filtering can only be enabled for @option{mode}
7833 @var{interleave_top} and @var{interleave_bottom}.
7840 Transpose rows with columns in the input video and optionally flip it.
7842 This filter accepts the following options:
7847 Specify the transposition direction.
7849 Can assume the following values:
7851 @item 0, 4, cclock_flip
7852 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
7860 Rotate by 90 degrees clockwise, that is:
7868 Rotate by 90 degrees counterclockwise, that is:
7875 @item 3, 7, clock_flip
7876 Rotate by 90 degrees clockwise and vertically flip, that is:
7884 For values between 4-7, the transposition is only done if the input
7885 video geometry is portrait and not landscape. These values are
7886 deprecated, the @code{passthrough} option should be used instead.
7888 Numerical values are deprecated, and should be dropped in favor of
7892 Do not apply the transposition if the input geometry matches the one
7893 specified by the specified value. It accepts the following values:
7896 Always apply transposition.
7898 Preserve portrait geometry (when @var{height} >= @var{width}).
7900 Preserve landscape geometry (when @var{width} >= @var{height}).
7903 Default value is @code{none}.
7906 For example to rotate by 90 degrees clockwise and preserve portrait
7909 transpose=dir=1:passthrough=portrait
7912 The command above can also be specified as:
7914 transpose=1:portrait
7918 Trim the input so that the output contains one continuous subpart of the input.
7920 This filter accepts the following options:
7923 Specify time of the start of the kept section, i.e. the frame with the
7924 timestamp @var{start} will be the first frame in the output.
7927 Specify time of the first frame that will be dropped, i.e. the frame
7928 immediately preceding the one with the timestamp @var{end} will be the last
7929 frame in the output.
7932 Same as @var{start}, except this option sets the start timestamp in timebase
7933 units instead of seconds.
7936 Same as @var{end}, except this option sets the end timestamp in timebase units
7940 Specify maximum duration of the output.
7943 Number of the first frame that should be passed to output.
7946 Number of the first frame that should be dropped.
7949 @option{start}, @option{end}, @option{duration} are expressed as time
7950 duration specifications, check the "Time duration" section in the
7951 ffmpeg-utils manual.
7953 Note that the first two sets of the start/end options and the @option{duration}
7954 option look at the frame timestamp, while the _frame variants simply count the
7955 frames that pass through the filter. Also note that this filter does not modify
7956 the timestamps. If you wish that the output timestamps start at zero, insert a
7957 setpts filter after the trim filter.
7959 If multiple start or end options are set, this filter tries to be greedy and
7960 keep all the frames that match at least one of the specified constraints. To keep
7961 only the part that matches all the constraints at once, chain multiple trim
7964 The defaults are such that all the input is kept. So it is possible to set e.g.
7965 just the end values to keep everything before the specified time.
7970 drop everything except the second minute of input
7972 ffmpeg -i INPUT -vf trim=60:120
7976 keep only the first second
7978 ffmpeg -i INPUT -vf trim=duration=1
7986 Sharpen or blur the input video.
7988 It accepts the following parameters:
7991 @item luma_msize_x, lx
7992 Set the luma matrix horizontal size. It must be an odd integer between
7993 3 and 63, default value is 5.
7995 @item luma_msize_y, ly
7996 Set the luma matrix vertical size. It must be an odd integer between 3
7997 and 63, default value is 5.
7999 @item luma_amount, la
8000 Set the luma effect strength. It can be a float number, reasonable
8001 values lay between -1.5 and 1.5.
8003 Negative values will blur the input video, while positive values will
8004 sharpen it, a value of zero will disable the effect.
8006 Default value is 1.0.
8008 @item chroma_msize_x, cx
8009 Set the chroma matrix horizontal size. It must be an odd integer
8010 between 3 and 63, default value is 5.
8012 @item chroma_msize_y, cy
8013 Set the chroma matrix vertical size. It must be an odd integer
8014 between 3 and 63, default value is 5.
8016 @item chroma_amount, ca
8017 Set the chroma effect strength. It can be a float number, reasonable
8018 values lay between -1.5 and 1.5.
8020 Negative values will blur the input video, while positive values will
8021 sharpen it, a value of zero will disable the effect.
8023 Default value is 0.0.
8026 If set to 1, specify using OpenCL capabilities, only available if
8027 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
8031 All parameters are optional and default to the equivalent of the
8032 string '5:5:1.0:5:5:0.0'.
8034 @subsection Examples
8038 Apply strong luma sharpen effect:
8040 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
8044 Apply strong blur of both luma and chroma parameters:
8046 unsharp=7:7:-2:7:7:-2
8050 @anchor{vidstabdetect}
8051 @section vidstabdetect
8053 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
8054 @ref{vidstabtransform} for pass 2.
8056 This filter generates a file with relative translation and rotation
8057 transform information about subsequent frames, which is then used by
8058 the @ref{vidstabtransform} filter.
8060 To enable compilation of this filter you need to configure FFmpeg with
8061 @code{--enable-libvidstab}.
8063 This filter accepts the following options:
8067 Set the path to the file used to write the transforms information.
8068 Default value is @file{transforms.trf}.
8071 Set how shaky the video is and how quick the camera is. It accepts an
8072 integer in the range 1-10, a value of 1 means little shakiness, a
8073 value of 10 means strong shakiness. Default value is 5.
8076 Set the accuracy of the detection process. It must be a value in the
8077 range 1-15. A value of 1 means low accuracy, a value of 15 means high
8078 accuracy. Default value is 15.
8081 Set stepsize of the search process. The region around minimum is
8082 scanned with 1 pixel resolution. Default value is 6.
8085 Set minimum contrast. Below this value a local measurement field is
8086 discarded. Must be a floating point value in the range 0-1. Default
8090 Set reference frame number for tripod mode.
8092 If enabled, the motion of the frames is compared to a reference frame
8093 in the filtered stream, identified by the specified number. The idea
8094 is to compensate all movements in a more-or-less static scene and keep
8095 the camera view absolutely still.
8097 If set to 0, it is disabled. The frames are counted starting from 1.
8100 Show fields and transforms in the resulting frames. It accepts an
8101 integer in the range 0-2. Default value is 0, which disables any
8105 @subsection Examples
8115 Analyze strongly shaky movie and put the results in file
8116 @file{mytransforms.trf}:
8118 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
8122 Visualize the result of internal transformations in the resulting
8125 vidstabdetect=show=1
8129 Analyze a video with medium shakiness using @command{ffmpeg}:
8131 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
8135 @anchor{vidstabtransform}
8136 @section vidstabtransform
8138 Video stabilization/deshaking: pass 2 of 2,
8139 see @ref{vidstabdetect} for pass 1.
8141 Read a file with transform information for each frame and
8142 apply/compensate them. Together with the @ref{vidstabdetect}
8143 filter this can be used to deshake videos. See also
8144 @url{http://public.hronopik.de/vid.stab}. It is important to also use
8145 the unsharp filter, see below.
8147 To enable compilation of this filter you need to configure FFmpeg with
8148 @code{--enable-libvidstab}.
8154 Set path to the file used to read the transforms. Default value is
8155 @file{transforms.trf}).
8158 Set the number of frames (value*2 + 1) used for lowpass filtering the
8159 camera movements. Default value is 10.
8161 For example a number of 10 means that 21 frames are used (10 in the
8162 past and 10 in the future) to smoothen the motion in the video. A
8163 larger values leads to a smoother video, but limits the acceleration
8164 of the camera (pan/tilt movements). 0 is a special case where a
8165 static camera is simulated.
8168 Set the camera path optimization algorithm.
8170 Accepted values are:
8173 gaussian kernel low-pass filter on camera motion (default)
8175 averaging on transformations
8179 Set maximal number of pixels to translate frames. Default value is -1,
8183 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
8184 value is -1, meaning no limit.
8187 Specify how to deal with borders that may be visible due to movement
8190 Available values are:
8193 keep image information from previous frame (default)
8195 fill the border black
8199 Invert transforms if set to 1. Default value is 0.
8202 Consider transforms as relative to previsou frame if set to 1,
8203 absolute if set to 0. Default value is 0.
8206 Set percentage to zoom. A positive value will result in a zoom-in
8207 effect, a negative value in a zoom-out effect. Default value is 0 (no
8211 Set optimal zooming to avoid borders.
8213 Accepted values are:
8218 optimal static zoom value is determined (only very strong movements
8219 will lead to visible borders) (default)
8221 optimal adaptive zoom value is determined (no borders will be
8222 visible), see @option{zoomspeed}
8225 Note that the value given at zoom is added to the one calculated here.
8228 Set percent to zoom maximally each frame (enabled when
8229 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
8233 Specify type of interpolation.
8235 Available values are:
8240 linear only horizontal
8242 linear in both directions (default)
8244 cubic in both directions (slow)
8248 Enable virtual tripod mode if set to 1, which is equivalent to
8249 @code{relative=0:smoothing=0}. Default value is 0.
8251 Use also @code{tripod} option of @ref{vidstabdetect}.
8254 Increase log verbosity if set to 1. Also the detected global motions
8255 are written to the temporary file @file{global_motions.trf}. Default
8259 @subsection Examples
8263 Use @command{ffmpeg} for a typical stabilization with default values:
8265 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
8268 Note the use of the unsharp filter which is always recommended.
8271 Zoom in a bit more and load transform data from a given file:
8273 vidstabtransform=zoom=5:input="mytransforms.trf"
8277 Smoothen the video even more:
8279 vidstabtransform=smoothing=30
8285 Flip the input video vertically.
8287 For example, to vertically flip a video with @command{ffmpeg}:
8289 ffmpeg -i in.avi -vf "vflip" out.avi
8294 Make or reverse a natural vignetting effect.
8296 The filter accepts the following options:
8300 Set lens angle expression as a number of radians.
8302 The value is clipped in the @code{[0,PI/2]} range.
8304 Default value: @code{"PI/5"}
8308 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
8312 Set forward/backward mode.
8314 Available modes are:
8317 The larger the distance from the central point, the darker the image becomes.
8320 The larger the distance from the central point, the brighter the image becomes.
8321 This can be used to reverse a vignette effect, though there is no automatic
8322 detection to extract the lens @option{angle} and other settings (yet). It can
8323 also be used to create a burning effect.
8326 Default value is @samp{forward}.
8329 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
8331 It accepts the following values:
8334 Evaluate expressions only once during the filter initialization.
8337 Evaluate expressions for each incoming frame. This is way slower than the
8338 @samp{init} mode since it requires all the scalers to be re-computed, but it
8339 allows advanced dynamic expressions.
8342 Default value is @samp{init}.
8345 Set dithering to reduce the circular banding effects. Default is @code{1}
8349 Set vignette aspect. This setting allows to adjust the shape of the vignette.
8350 Setting this value to the SAR of the input will make a rectangular vignetting
8351 following the dimensions of the video.
8353 Default is @code{1/1}.
8356 @subsection Expressions
8358 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
8359 following parameters.
8364 input width and height
8367 the number of input frame, starting from 0
8370 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
8371 @var{TB} units, NAN if undefined
8374 frame rate of the input video, NAN if the input frame rate is unknown
8377 the PTS (Presentation TimeStamp) of the filtered video frame,
8378 expressed in seconds, NAN if undefined
8381 time base of the input video
8385 @subsection Examples
8389 Apply simple strong vignetting effect:
8395 Make a flickering vignetting:
8397 vignette='PI/4+random(1)*PI/50':eval=frame
8404 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
8405 Deinterlacing Filter").
8407 Based on the process described by Martin Weston for BBC R&D, and
8408 implemented based on the de-interlace algorithm written by Jim
8409 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
8410 uses filter coefficients calculated by BBC R&D.
8412 There are two sets of filter coefficients, so called "simple":
8413 and "complex". Which set of filter coefficients is used can
8414 be set by passing an optional parameter:
8418 Set the interlacing filter coefficients. Accepts one of the following values:
8422 Simple filter coefficient set.
8424 More-complex filter coefficient set.
8426 Default value is @samp{complex}.
8429 Specify which frames to deinterlace. Accept one of the following values:
8433 Deinterlace all frames,
8435 Only deinterlace frames marked as interlaced.
8438 Default value is @samp{all}.
8444 Deinterlace the input video ("yadif" means "yet another deinterlacing
8447 This filter accepts the following options:
8453 The interlacing mode to adopt, accepts one of the following values:
8457 output 1 frame for each frame
8459 output 1 frame for each field
8460 @item 2, send_frame_nospatial
8461 like @code{send_frame} but skip spatial interlacing check
8462 @item 3, send_field_nospatial
8463 like @code{send_field} but skip spatial interlacing check
8466 Default value is @code{send_frame}.
8469 The picture field parity assumed for the input interlaced video, accepts one of
8470 the following values:
8474 assume top field first
8476 assume bottom field first
8478 enable automatic detection
8481 Default value is @code{auto}.
8482 If interlacing is unknown or decoder does not export this information,
8483 top field first will be assumed.
8486 Specify which frames to deinterlace. Accept one of the following
8491 deinterlace all frames
8493 only deinterlace frames marked as interlaced
8496 Default value is @code{all}.
8499 @c man end VIDEO FILTERS
8501 @chapter Video Sources
8502 @c man begin VIDEO SOURCES
8504 Below is a description of the currently available video sources.
8508 Buffer video frames, and make them available to the filter chain.
8510 This source is mainly intended for a programmatic use, in particular
8511 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
8513 This source accepts the following options:
8518 Specify the size (width and height) of the buffered video frames. For the
8519 syntax of this option, check the "Video size" section in the ffmpeg-utils
8529 A string representing the pixel format of the buffered video frames.
8530 It may be a number corresponding to a pixel format, or a pixel format
8534 Specify the timebase assumed by the timestamps of the buffered frames.
8537 Specify the frame rate expected for the video stream.
8539 @item pixel_aspect, sar
8540 Specify the sample aspect ratio assumed by the video frames.
8543 Specify the optional parameters to be used for the scale filter which
8544 is automatically inserted when an input change is detected in the
8545 input size or format.
8550 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
8553 will instruct the source to accept video frames with size 320x240 and
8554 with format "yuv410p", assuming 1/24 as the timestamps timebase and
8555 square pixels (1:1 sample aspect ratio).
8556 Since the pixel format with name "yuv410p" corresponds to the number 6
8557 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
8558 this example corresponds to:
8560 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
8563 Alternatively, the options can be specified as a flat string, but this
8564 syntax is deprecated:
8566 @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}]
8570 Create a pattern generated by an elementary cellular automaton.
8572 The initial state of the cellular automaton can be defined through the
8573 @option{filename}, and @option{pattern} options. If such options are
8574 not specified an initial state is created randomly.
8576 At each new frame a new row in the video is filled with the result of
8577 the cellular automaton next generation. The behavior when the whole
8578 frame is filled is defined by the @option{scroll} option.
8580 This source accepts the following options:
8584 Read the initial cellular automaton state, i.e. the starting row, from
8586 In the file, each non-whitespace character is considered an alive
8587 cell, a newline will terminate the row, and further characters in the
8588 file will be ignored.
8591 Read the initial cellular automaton state, i.e. the starting row, from
8592 the specified string.
8594 Each non-whitespace character in the string is considered an alive
8595 cell, a newline will terminate the row, and further characters in the
8596 string will be ignored.
8599 Set the video rate, that is the number of frames generated per second.
8602 @item random_fill_ratio, ratio
8603 Set the random fill ratio for the initial cellular automaton row. It
8604 is a floating point number value ranging from 0 to 1, defaults to
8607 This option is ignored when a file or a pattern is specified.
8609 @item random_seed, seed
8610 Set the seed for filling randomly the initial row, must be an integer
8611 included between 0 and UINT32_MAX. If not specified, or if explicitly
8612 set to -1, the filter will try to use a good random seed on a best
8616 Set the cellular automaton rule, it is a number ranging from 0 to 255.
8617 Default value is 110.
8620 Set the size of the output video. For the syntax of this option, check
8621 the "Video size" section in the ffmpeg-utils manual.
8623 If @option{filename} or @option{pattern} is specified, the size is set
8624 by default to the width of the specified initial state row, and the
8625 height is set to @var{width} * PHI.
8627 If @option{size} is set, it must contain the width of the specified
8628 pattern string, and the specified pattern will be centered in the
8631 If a filename or a pattern string is not specified, the size value
8632 defaults to "320x518" (used for a randomly generated initial state).
8635 If set to 1, scroll the output upward when all the rows in the output
8636 have been already filled. If set to 0, the new generated row will be
8637 written over the top row just after the bottom row is filled.
8640 @item start_full, full
8641 If set to 1, completely fill the output with generated rows before
8642 outputting the first frame.
8643 This is the default behavior, for disabling set the value to 0.
8646 If set to 1, stitch the left and right row edges together.
8647 This is the default behavior, for disabling set the value to 0.
8650 @subsection Examples
8654 Read the initial state from @file{pattern}, and specify an output of
8657 cellauto=f=pattern:s=200x400
8661 Generate a random initial row with a width of 200 cells, with a fill
8664 cellauto=ratio=2/3:s=200x200
8668 Create a pattern generated by rule 18 starting by a single alive cell
8669 centered on an initial row with width 100:
8671 cellauto=p=@@:s=100x400:full=0:rule=18
8675 Specify a more elaborated initial pattern:
8677 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
8684 Generate a Mandelbrot set fractal, and progressively zoom towards the
8685 point specified with @var{start_x} and @var{start_y}.
8687 This source accepts the following options:
8692 Set the terminal pts value. Default value is 400.
8695 Set the terminal scale value.
8696 Must be a floating point value. Default value is 0.3.
8699 Set the inner coloring mode, that is the algorithm used to draw the
8700 Mandelbrot fractal internal region.
8702 It shall assume one of the following values:
8707 Show time until convergence.
8709 Set color based on point closest to the origin of the iterations.
8714 Default value is @var{mincol}.
8717 Set the bailout value. Default value is 10.0.
8720 Set the maximum of iterations performed by the rendering
8721 algorithm. Default value is 7189.
8724 Set outer coloring mode.
8725 It shall assume one of following values:
8727 @item iteration_count
8728 Set iteration cound mode.
8729 @item normalized_iteration_count
8730 set normalized iteration count mode.
8732 Default value is @var{normalized_iteration_count}.
8735 Set frame rate, expressed as number of frames per second. Default
8739 Set frame size. For the syntax of this option, check the "Video
8740 size" section in the ffmpeg-utils manual. Default value is "640x480".
8743 Set the initial scale value. Default value is 3.0.
8746 Set the initial x position. Must be a floating point value between
8747 -100 and 100. Default value is -0.743643887037158704752191506114774.
8750 Set the initial y position. Must be a floating point value between
8751 -100 and 100. Default value is -0.131825904205311970493132056385139.
8756 Generate various test patterns, as generated by the MPlayer test filter.
8758 The size of the generated video is fixed, and is 256x256.
8759 This source is useful in particular for testing encoding features.
8761 This source accepts the following options:
8766 Specify the frame rate of the sourced video, as the number of frames
8767 generated per second. It has to be a string in the format
8768 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
8769 number or a valid video frame rate abbreviation. The default value is
8773 Set the video duration of the sourced video. The accepted syntax is:
8778 See also the function @code{av_parse_time()}.
8780 If not specified, or the expressed duration is negative, the video is
8781 supposed to be generated forever.
8785 Set the number or the name of the test to perform. Supported tests are:
8800 Default value is "all", which will cycle through the list of all tests.
8803 For example the following:
8808 will generate a "dc_luma" test pattern.
8812 Provide a frei0r source.
8814 To enable compilation of this filter you need to install the frei0r
8815 header and configure FFmpeg with @code{--enable-frei0r}.
8817 This source accepts the following options:
8822 The size of the video to generate. For the syntax of this option, check the
8823 "Video size" section in the ffmpeg-utils manual.
8826 Framerate of the generated video, may be a string of the form
8827 @var{num}/@var{den} or a frame rate abbreviation.
8830 The name to the frei0r source to load. For more information regarding frei0r and
8831 how to set the parameters read the section @ref{frei0r} in the description of
8835 A '|'-separated list of parameters to pass to the frei0r source.
8839 For example, to generate a frei0r partik0l source with size 200x200
8840 and frame rate 10 which is overlayed on the overlay filter main input:
8842 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
8847 Generate a life pattern.
8849 This source is based on a generalization of John Conway's life game.
8851 The sourced input represents a life grid, each pixel represents a cell
8852 which can be in one of two possible states, alive or dead. Every cell
8853 interacts with its eight neighbours, which are the cells that are
8854 horizontally, vertically, or diagonally adjacent.
8856 At each interaction the grid evolves according to the adopted rule,
8857 which specifies the number of neighbor alive cells which will make a
8858 cell stay alive or born. The @option{rule} option allows to specify
8861 This source accepts the following options:
8865 Set the file from which to read the initial grid state. In the file,
8866 each non-whitespace character is considered an alive cell, and newline
8867 is used to delimit the end of each row.
8869 If this option is not specified, the initial grid is generated
8873 Set the video rate, that is the number of frames generated per second.
8876 @item random_fill_ratio, ratio
8877 Set the random fill ratio for the initial random grid. It is a
8878 floating point number value ranging from 0 to 1, defaults to 1/PHI.
8879 It is ignored when a file is specified.
8881 @item random_seed, seed
8882 Set the seed for filling the initial random grid, must be an integer
8883 included between 0 and UINT32_MAX. If not specified, or if explicitly
8884 set to -1, the filter will try to use a good random seed on a best
8890 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
8891 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
8892 @var{NS} specifies the number of alive neighbor cells which make a
8893 live cell stay alive, and @var{NB} the number of alive neighbor cells
8894 which make a dead cell to become alive (i.e. to "born").
8895 "s" and "b" can be used in place of "S" and "B", respectively.
8897 Alternatively a rule can be specified by an 18-bits integer. The 9
8898 high order bits are used to encode the next cell state if it is alive
8899 for each number of neighbor alive cells, the low order bits specify
8900 the rule for "borning" new cells. Higher order bits encode for an
8901 higher number of neighbor cells.
8902 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
8903 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
8905 Default value is "S23/B3", which is the original Conway's game of life
8906 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
8907 cells, and will born a new cell if there are three alive cells around
8911 Set the size of the output video. For the syntax of this option, check the
8912 "Video size" section in the ffmpeg-utils manual.
8914 If @option{filename} is specified, the size is set by default to the
8915 same size of the input file. If @option{size} is set, it must contain
8916 the size specified in the input file, and the initial grid defined in
8917 that file is centered in the larger resulting area.
8919 If a filename is not specified, the size value defaults to "320x240"
8920 (used for a randomly generated initial grid).
8923 If set to 1, stitch the left and right grid edges together, and the
8924 top and bottom edges also. Defaults to 1.
8927 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
8928 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
8929 value from 0 to 255.
8932 Set the color of living (or new born) cells.
8935 Set the color of dead cells. If @option{mold} is set, this is the first color
8936 used to represent a dead cell.
8939 Set mold color, for definitely dead and moldy cells.
8941 For the syntax of these 3 color options, check the "Color" section in the
8942 ffmpeg-utils manual.
8945 @subsection Examples
8949 Read a grid from @file{pattern}, and center it on a grid of size
8952 life=f=pattern:s=300x300
8956 Generate a random grid of size 200x200, with a fill ratio of 2/3:
8958 life=ratio=2/3:s=200x200
8962 Specify a custom rule for evolving a randomly generated grid:
8968 Full example with slow death effect (mold) using @command{ffplay}:
8970 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
8975 @anchor{haldclutsrc}
8979 @anchor{smptehdbars}
8981 @section color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
8983 The @code{color} source provides an uniformly colored input.
8985 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
8986 @ref{haldclut} filter.
8988 The @code{nullsrc} source returns unprocessed video frames. It is
8989 mainly useful to be employed in analysis / debugging tools, or as the
8990 source for filters which ignore the input data.
8992 The @code{rgbtestsrc} source generates an RGB test pattern useful for
8993 detecting RGB vs BGR issues. You should see a red, green and blue
8994 stripe from top to bottom.
8996 The @code{smptebars} source generates a color bars pattern, based on
8997 the SMPTE Engineering Guideline EG 1-1990.
8999 The @code{smptehdbars} source generates a color bars pattern, based on
9000 the SMPTE RP 219-2002.
9002 The @code{testsrc} source generates a test video pattern, showing a
9003 color pattern, a scrolling gradient and a timestamp. This is mainly
9004 intended for testing purposes.
9006 The sources accept the following options:
9011 Specify the color of the source, only available in the @code{color}
9012 source. For the syntax of this option, check the "Color" section in the
9013 ffmpeg-utils manual.
9016 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
9017 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
9018 pixels to be used as identity matrix for 3D lookup tables. Each component is
9019 coded on a @code{1/(N*N)} scale.
9022 Specify the size of the sourced video. For the syntax of this option, check the
9023 "Video size" section in the ffmpeg-utils manual. The default value is
9026 This option is not available with the @code{haldclutsrc} filter.
9029 Specify the frame rate of the sourced video, as the number of frames
9030 generated per second. It has to be a string in the format
9031 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
9032 number or a valid video frame rate abbreviation. The default value is
9036 Set the sample aspect ratio of the sourced video.
9039 Set the video duration of the sourced video. The accepted syntax is:
9041 [-]HH[:MM[:SS[.m...]]]
9044 See also the function @code{av_parse_time()}.
9046 If not specified, or the expressed duration is negative, the video is
9047 supposed to be generated forever.
9050 Set the number of decimals to show in the timestamp, only available in the
9051 @code{testsrc} source.
9053 The displayed timestamp value will correspond to the original
9054 timestamp value multiplied by the power of 10 of the specified
9055 value. Default value is 0.
9058 For example the following:
9060 testsrc=duration=5.3:size=qcif:rate=10
9063 will generate a video with a duration of 5.3 seconds, with size
9064 176x144 and a frame rate of 10 frames per second.
9066 The following graph description will generate a red source
9067 with an opacity of 0.2, with size "qcif" and a frame rate of 10
9070 color=c=red@@0.2:s=qcif:r=10
9073 If the input content is to be ignored, @code{nullsrc} can be used. The
9074 following command generates noise in the luminance plane by employing
9075 the @code{geq} filter:
9077 nullsrc=s=256x256, geq=random(1)*255:128:128
9080 @subsection Commands
9082 The @code{color} source supports the following commands:
9086 Set the color of the created image. Accepts the same syntax of the
9087 corresponding @option{color} option.
9090 @c man end VIDEO SOURCES
9092 @chapter Video Sinks
9093 @c man begin VIDEO SINKS
9095 Below is a description of the currently available video sinks.
9099 Buffer video frames, and make them available to the end of the filter
9102 This sink is mainly intended for a programmatic use, in particular
9103 through the interface defined in @file{libavfilter/buffersink.h}
9104 or the options system.
9106 It accepts a pointer to an AVBufferSinkContext structure, which
9107 defines the incoming buffers' formats, to be passed as the opaque
9108 parameter to @code{avfilter_init_filter} for initialization.
9112 Null video sink, do absolutely nothing with the input video. It is
9113 mainly useful as a template and to be employed in analysis / debugging
9116 @c man end VIDEO SINKS
9118 @chapter Multimedia Filters
9119 @c man begin MULTIMEDIA FILTERS
9121 Below is a description of the currently available multimedia filters.
9123 @section avectorscope
9125 Convert input audio to a video output, representing the audio vector
9128 The filter is used to measure the difference between channels of stereo
9129 audio stream. A monoaural signal, consisting of identical left and right
9130 signal, results in straight vertical line. Any stereo separation is visible
9131 as a deviation from this line, creating a Lissajous figure.
9132 If the straight (or deviation from it) but horizontal line appears this
9133 indicates that the left and right channels are out of phase.
9135 The filter accepts the following options:
9139 Set the vectorscope mode.
9141 Available values are:
9144 Lissajous rotated by 45 degrees.
9147 Same as above but not rotated.
9150 Default value is @samp{lissajous}.
9153 Set the video size for the output. For the syntax of this option, check the "Video size"
9154 section in the ffmpeg-utils manual. Default value is @code{400x400}.
9157 Set the output frame rate. Default value is @code{25}.
9162 Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}.
9163 Allowed range is @code{[0, 255]}.
9168 Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}.
9169 Allowed range is @code{[0, 255]}.
9172 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
9175 @subsection Examples
9179 Complete example using @command{ffplay}:
9181 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
9182 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
9188 Concatenate audio and video streams, joining them together one after the
9191 The filter works on segments of synchronized video and audio streams. All
9192 segments must have the same number of streams of each type, and that will
9193 also be the number of streams at output.
9195 The filter accepts the following options:
9200 Set the number of segments. Default is 2.
9203 Set the number of output video streams, that is also the number of video
9204 streams in each segment. Default is 1.
9207 Set the number of output audio streams, that is also the number of video
9208 streams in each segment. Default is 0.
9211 Activate unsafe mode: do not fail if segments have a different format.
9215 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
9216 @var{a} audio outputs.
9218 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
9219 segment, in the same order as the outputs, then the inputs for the second
9222 Related streams do not always have exactly the same duration, for various
9223 reasons including codec frame size or sloppy authoring. For that reason,
9224 related synchronized streams (e.g. a video and its audio track) should be
9225 concatenated at once. The concat filter will use the duration of the longest
9226 stream in each segment (except the last one), and if necessary pad shorter
9227 audio streams with silence.
9229 For this filter to work correctly, all segments must start at timestamp 0.
9231 All corresponding streams must have the same parameters in all segments; the
9232 filtering system will automatically select a common pixel format for video
9233 streams, and a common sample format, sample rate and channel layout for
9234 audio streams, but other settings, such as resolution, must be converted
9235 explicitly by the user.
9237 Different frame rates are acceptable but will result in variable frame rate
9238 at output; be sure to configure the output file to handle it.
9240 @subsection Examples
9244 Concatenate an opening, an episode and an ending, all in bilingual version
9245 (video in stream 0, audio in streams 1 and 2):
9247 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
9248 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
9249 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
9250 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
9254 Concatenate two parts, handling audio and video separately, using the
9255 (a)movie sources, and adjusting the resolution:
9257 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
9258 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
9259 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
9261 Note that a desync will happen at the stitch if the audio and video streams
9262 do not have exactly the same duration in the first file.
9268 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
9269 it unchanged. By default, it logs a message at a frequency of 10Hz with the
9270 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
9271 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
9273 The filter also has a video output (see the @var{video} option) with a real
9274 time graph to observe the loudness evolution. The graphic contains the logged
9275 message mentioned above, so it is not printed anymore when this option is set,
9276 unless the verbose logging is set. The main graphing area contains the
9277 short-term loudness (3 seconds of analysis), and the gauge on the right is for
9278 the momentary loudness (400 milliseconds).
9280 More information about the Loudness Recommendation EBU R128 on
9281 @url{http://tech.ebu.ch/loudness}.
9283 The filter accepts the following options:
9288 Activate the video output. The audio stream is passed unchanged whether this
9289 option is set or no. The video stream will be the first output stream if
9290 activated. Default is @code{0}.
9293 Set the video size. This option is for video only. For the syntax of this
9294 option, check the "Video size" section in the ffmpeg-utils manual. Default
9295 and minimum resolution is @code{640x480}.
9298 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
9299 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
9300 other integer value between this range is allowed.
9303 Set metadata injection. If set to @code{1}, the audio input will be segmented
9304 into 100ms output frames, each of them containing various loudness information
9305 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
9307 Default is @code{0}.
9310 Force the frame logging level.
9312 Available values are:
9315 information logging level
9317 verbose logging level
9320 By default, the logging level is set to @var{info}. If the @option{video} or
9321 the @option{metadata} options are set, it switches to @var{verbose}.
9324 @subsection Examples
9328 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
9330 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
9334 Run an analysis with @command{ffmpeg}:
9336 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
9340 @section interleave, ainterleave
9342 Temporally interleave frames from several inputs.
9344 @code{interleave} works with video inputs, @code{ainterleave} with audio.
9346 These filters read frames from several inputs and send the oldest
9347 queued frame to the output.
9349 Input streams must have a well defined, monotonically increasing frame
9352 In order to submit one frame to output, these filters need to enqueue
9353 at least one frame for each input, so they cannot work in case one
9354 input is not yet terminated and will not receive incoming frames.
9356 For example consider the case when one input is a @code{select} filter
9357 which always drop input frames. The @code{interleave} filter will keep
9358 reading from that input, but it will never be able to send new frames
9359 to output until the input will send an end-of-stream signal.
9361 Also, depending on inputs synchronization, the filters will drop
9362 frames in case one input receives more frames than the other ones, and
9363 the queue is already filled.
9365 These filters accept the following options:
9369 Set the number of different inputs, it is 2 by default.
9372 @subsection Examples
9376 Interleave frames belonging to different streams using @command{ffmpeg}:
9378 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
9382 Add flickering blur effect:
9384 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
9388 @section perms, aperms
9390 Set read/write permissions for the output frames.
9392 These filters are mainly aimed at developers to test direct path in the
9393 following filter in the filtergraph.
9395 The filters accept the following options:
9399 Select the permissions mode.
9401 It accepts the following values:
9404 Do nothing. This is the default.
9406 Set all the output frames read-only.
9408 Set all the output frames directly writable.
9410 Make the frame read-only if writable, and writable if read-only.
9412 Set each output frame read-only or writable randomly.
9416 Set the seed for the @var{random} mode, must be an integer included between
9417 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9418 @code{-1}, the filter will try to use a good random seed on a best effort
9422 Note: in case of auto-inserted filter between the permission filter and the
9423 following one, the permission might not be received as expected in that
9424 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
9425 perms/aperms filter can avoid this problem.
9427 @section select, aselect
9429 Select frames to pass in output.
9431 This filter accepts the following options:
9436 Set expression, which is evaluated for each input frame.
9438 If the expression is evaluated to zero, the frame is discarded.
9440 If the evaluation result is negative or NaN, the frame is sent to the
9441 first output; otherwise it is sent to the output with index
9442 @code{ceil(val)-1}, assuming that the input index starts from 0.
9444 For example a value of @code{1.2} corresponds to the output with index
9445 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
9448 Set the number of outputs. The output to which to send the selected
9449 frame is based on the result of the evaluation. Default value is 1.
9452 The expression can contain the following constants:
9456 the sequential number of the filtered frame, starting from 0
9459 the sequential number of the selected frame, starting from 0
9461 @item prev_selected_n
9462 the sequential number of the last selected frame, NAN if undefined
9465 timebase of the input timestamps
9468 the PTS (Presentation TimeStamp) of the filtered video frame,
9469 expressed in @var{TB} units, NAN if undefined
9472 the PTS (Presentation TimeStamp) of the filtered video frame,
9473 expressed in seconds, NAN if undefined
9476 the PTS of the previously filtered video frame, NAN if undefined
9478 @item prev_selected_pts
9479 the PTS of the last previously filtered video frame, NAN if undefined
9481 @item prev_selected_t
9482 the PTS of the last previously selected video frame, NAN if undefined
9485 the PTS of the first video frame in the video, NAN if undefined
9488 the time of the first video frame in the video, NAN if undefined
9490 @item pict_type @emph{(video only)}
9491 the type of the filtered frame, can assume one of the following
9503 @item interlace_type @emph{(video only)}
9504 the frame interlace type, can assume one of the following values:
9507 the frame is progressive (not interlaced)
9509 the frame is top-field-first
9511 the frame is bottom-field-first
9514 @item consumed_sample_n @emph{(audio only)}
9515 the number of selected samples before the current frame
9517 @item samples_n @emph{(audio only)}
9518 the number of samples in the current frame
9520 @item sample_rate @emph{(audio only)}
9521 the input sample rate
9524 1 if the filtered frame is a key-frame, 0 otherwise
9527 the position in the file of the filtered frame, -1 if the information
9528 is not available (e.g. for synthetic video)
9530 @item scene @emph{(video only)}
9531 value between 0 and 1 to indicate a new scene; a low value reflects a low
9532 probability for the current frame to introduce a new scene, while a higher
9533 value means the current frame is more likely to be one (see the example below)
9537 The default value of the select expression is "1".
9539 @subsection Examples
9543 Select all frames in input:
9548 The example above is the same as:
9560 Select only I-frames:
9562 select='eq(pict_type\,I)'
9566 Select one frame every 100:
9568 select='not(mod(n\,100))'
9572 Select only frames contained in the 10-20 time interval:
9574 select=between(t\,10\,20)
9578 Select only I frames contained in the 10-20 time interval:
9580 select=between(t\,10\,20)*eq(pict_type\,I)
9584 Select frames with a minimum distance of 10 seconds:
9586 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
9590 Use aselect to select only audio frames with samples number > 100:
9592 aselect='gt(samples_n\,100)'
9596 Create a mosaic of the first scenes:
9598 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
9601 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
9605 Send even and odd frames to separate outputs, and compose them:
9607 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
9611 @section sendcmd, asendcmd
9613 Send commands to filters in the filtergraph.
9615 These filters read commands to be sent to other filters in the
9618 @code{sendcmd} must be inserted between two video filters,
9619 @code{asendcmd} must be inserted between two audio filters, but apart
9620 from that they act the same way.
9622 The specification of commands can be provided in the filter arguments
9623 with the @var{commands} option, or in a file specified by the
9624 @var{filename} option.
9626 These filters accept the following options:
9629 Set the commands to be read and sent to the other filters.
9631 Set the filename of the commands to be read and sent to the other
9635 @subsection Commands syntax
9637 A commands description consists of a sequence of interval
9638 specifications, comprising a list of commands to be executed when a
9639 particular event related to that interval occurs. The occurring event
9640 is typically the current frame time entering or leaving a given time
9643 An interval is specified by the following syntax:
9645 @var{START}[-@var{END}] @var{COMMANDS};
9648 The time interval is specified by the @var{START} and @var{END} times.
9649 @var{END} is optional and defaults to the maximum time.
9651 The current frame time is considered within the specified interval if
9652 it is included in the interval [@var{START}, @var{END}), that is when
9653 the time is greater or equal to @var{START} and is lesser than
9656 @var{COMMANDS} consists of a sequence of one or more command
9657 specifications, separated by ",", relating to that interval. The
9658 syntax of a command specification is given by:
9660 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
9663 @var{FLAGS} is optional and specifies the type of events relating to
9664 the time interval which enable sending the specified command, and must
9665 be a non-null sequence of identifier flags separated by "+" or "|" and
9666 enclosed between "[" and "]".
9668 The following flags are recognized:
9671 The command is sent when the current frame timestamp enters the
9672 specified interval. In other words, the command is sent when the
9673 previous frame timestamp was not in the given interval, and the
9677 The command is sent when the current frame timestamp leaves the
9678 specified interval. In other words, the command is sent when the
9679 previous frame timestamp was in the given interval, and the
9683 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
9686 @var{TARGET} specifies the target of the command, usually the name of
9687 the filter class or a specific filter instance name.
9689 @var{COMMAND} specifies the name of the command for the target filter.
9691 @var{ARG} is optional and specifies the optional list of argument for
9692 the given @var{COMMAND}.
9694 Between one interval specification and another, whitespaces, or
9695 sequences of characters starting with @code{#} until the end of line,
9696 are ignored and can be used to annotate comments.
9698 A simplified BNF description of the commands specification syntax
9701 @var{COMMAND_FLAG} ::= "enter" | "leave"
9702 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
9703 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
9704 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
9705 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
9706 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
9709 @subsection Examples
9713 Specify audio tempo change at second 4:
9715 asendcmd=c='4.0 atempo tempo 1.5',atempo
9719 Specify a list of drawtext and hue commands in a file.
9721 # show text in the interval 5-10
9722 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
9723 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
9725 # desaturate the image in the interval 15-20
9726 15.0-20.0 [enter] hue s 0,
9727 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
9729 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
9731 # apply an exponential saturation fade-out effect, starting from time 25
9732 25 [enter] hue s exp(25-t)
9735 A filtergraph allowing to read and process the above command list
9736 stored in a file @file{test.cmd}, can be specified with:
9738 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
9743 @section setpts, asetpts
9745 Change the PTS (presentation timestamp) of the input frames.
9747 @code{setpts} works on video frames, @code{asetpts} on audio frames.
9749 This filter accepts the following options:
9754 The expression which is evaluated for each frame to construct its timestamp.
9758 The expression is evaluated through the eval API and can contain the following
9763 frame rate, only defined for constant frame-rate video
9766 the presentation timestamp in input
9769 the count of the input frame for video or the number of consumed samples,
9770 not including the current frame for audio, starting from 0.
9772 @item NB_CONSUMED_SAMPLES
9773 the number of consumed samples, not including the current frame (only
9777 the number of samples in the current frame (only audio)
9779 @item SAMPLE_RATE, SR
9783 the PTS of the first frame
9786 the time in seconds of the first frame
9789 tell if the current frame is interlaced
9792 the time in seconds of the current frame
9795 original position in the file of the frame, or undefined if undefined
9796 for the current frame
9802 previous input time in seconds
9808 previous output time in seconds
9811 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
9815 wallclock (RTC) time at the start of the movie in microseconds
9818 timebase of the input timestamps
9822 @subsection Examples
9826 Start counting PTS from zero
9832 Apply fast motion effect:
9838 Apply slow motion effect:
9844 Set fixed rate of 25 frames per second:
9850 Set fixed rate 25 fps with some jitter:
9852 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
9856 Apply an offset of 10 seconds to the input PTS:
9862 Generate timestamps from a "live source" and rebase onto the current timebase:
9864 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
9868 Generate timestamps by counting samples:
9875 @section settb, asettb
9877 Set the timebase to use for the output frames timestamps.
9878 It is mainly useful for testing timebase configuration.
9880 This filter accepts the following options:
9885 The expression which is evaluated into the output timebase.
9889 The value for @option{tb} is an arithmetic expression representing a
9890 rational. The expression can contain the constants "AVTB" (the default
9891 timebase), "intb" (the input timebase) and "sr" (the sample rate,
9892 audio only). Default value is "intb".
9894 @subsection Examples
9898 Set the timebase to 1/25:
9904 Set the timebase to 1/10:
9910 Set the timebase to 1001/1000:
9916 Set the timebase to 2*intb:
9922 Set the default timebase value:
9928 @section showspectrum
9930 Convert input audio to a video output, representing the audio frequency
9933 The filter accepts the following options:
9937 Specify the video size for the output. For the syntax of this option, check
9938 the "Video size" section in the ffmpeg-utils manual. Default value is
9942 Specify if the spectrum should slide along the window. Default value is
9946 Specify display mode.
9948 It accepts the following values:
9951 all channels are displayed in the same row
9953 all channels are displayed in separate rows
9956 Default value is @samp{combined}.
9959 Specify display color mode.
9961 It accepts the following values:
9964 each channel is displayed in a separate color
9966 each channel is is displayed using the same color scheme
9969 Default value is @samp{channel}.
9972 Specify scale used for calculating intensity color values.
9974 It accepts the following values:
9979 square root, default
9986 Default value is @samp{sqrt}.
9989 Set saturation modifier for displayed colors. Negative values provide
9990 alternative color scheme. @code{0} is no saturation at all.
9991 Saturation must be in [-10.0, 10.0] range.
9992 Default value is @code{1}.
9995 Set window function.
9997 It accepts the following values:
10000 No samples pre-processing (do not expect this to be faster)
10009 Default value is @code{hann}.
10012 The usage is very similar to the showwaves filter; see the examples in that
10015 @subsection Examples
10019 Large window with logarithmic color scaling:
10021 showspectrum=s=1280x480:scale=log
10025 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
10027 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
10028 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
10034 Convert input audio to a video output, representing the samples waves.
10036 The filter accepts the following options:
10040 Specify the video size for the output. For the syntax of this option, check
10041 the "Video size" section in the ffmpeg-utils manual. Default value
10047 Available values are:
10050 Draw a point for each sample.
10053 Draw a vertical line for each sample.
10056 Default value is @code{point}.
10059 Set the number of samples which are printed on the same column. A
10060 larger value will decrease the frame rate. Must be a positive
10061 integer. This option can be set only if the value for @var{rate}
10062 is not explicitly specified.
10065 Set the (approximate) output frame rate. This is done by setting the
10066 option @var{n}. Default value is "25".
10070 @subsection Examples
10074 Output the input file audio and the corresponding video representation
10077 amovie=a.mp3,asplit[out0],showwaves[out1]
10081 Create a synthetic signal and show it with showwaves, forcing a
10082 frame rate of 30 frames per second:
10084 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
10088 @section split, asplit
10090 Split input into several identical outputs.
10092 @code{asplit} works with audio input, @code{split} with video.
10094 The filter accepts a single parameter which specifies the number of outputs. If
10095 unspecified, it defaults to 2.
10097 @subsection Examples
10101 Create two separate outputs from the same input:
10103 [in] split [out0][out1]
10107 To create 3 or more outputs, you need to specify the number of
10110 [in] asplit=3 [out0][out1][out2]
10114 Create two separate outputs from the same input, one cropped and
10117 [in] split [splitout1][splitout2];
10118 [splitout1] crop=100:100:0:0 [cropout];
10119 [splitout2] pad=200:200:100:100 [padout];
10123 Create 5 copies of the input audio with @command{ffmpeg}:
10125 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
10131 Receive commands sent through a libzmq client, and forward them to
10132 filters in the filtergraph.
10134 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
10135 must be inserted between two video filters, @code{azmq} between two
10138 To enable these filters you need to install the libzmq library and
10139 headers and configure FFmpeg with @code{--enable-libzmq}.
10141 For more information about libzmq see:
10142 @url{http://www.zeromq.org/}
10144 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
10145 receives messages sent through a network interface defined by the
10146 @option{bind_address} option.
10148 The received message must be in the form:
10150 @var{TARGET} @var{COMMAND} [@var{ARG}]
10153 @var{TARGET} specifies the target of the command, usually the name of
10154 the filter class or a specific filter instance name.
10156 @var{COMMAND} specifies the name of the command for the target filter.
10158 @var{ARG} is optional and specifies the optional argument list for the
10159 given @var{COMMAND}.
10161 Upon reception, the message is processed and the corresponding command
10162 is injected into the filtergraph. Depending on the result, the filter
10163 will send a reply to the client, adopting the format:
10165 @var{ERROR_CODE} @var{ERROR_REASON}
10169 @var{MESSAGE} is optional.
10171 @subsection Examples
10173 Look at @file{tools/zmqsend} for an example of a zmq client which can
10174 be used to send commands processed by these filters.
10176 Consider the following filtergraph generated by @command{ffplay}
10178 ffplay -dumpgraph 1 -f lavfi "
10179 color=s=100x100:c=red [l];
10180 color=s=100x100:c=blue [r];
10181 nullsrc=s=200x100, zmq [bg];
10182 [bg][l] overlay [bg+l];
10183 [bg+l][r] overlay=x=100 "
10186 To change the color of the left side of the video, the following
10187 command can be used:
10189 echo Parsed_color_0 c yellow | tools/zmqsend
10192 To change the right side:
10194 echo Parsed_color_1 c pink | tools/zmqsend
10197 @c man end MULTIMEDIA FILTERS
10199 @chapter Multimedia Sources
10200 @c man begin MULTIMEDIA SOURCES
10202 Below is a description of the currently available multimedia sources.
10206 This is the same as @ref{movie} source, except it selects an audio
10212 Read audio and/or video stream(s) from a movie container.
10214 This filter accepts the following options:
10218 The name of the resource to read (not necessarily a file but also a device or a
10219 stream accessed through some protocol).
10221 @item format_name, f
10222 Specifies the format assumed for the movie to read, and can be either
10223 the name of a container or an input device. If not specified the
10224 format is guessed from @var{movie_name} or by probing.
10226 @item seek_point, sp
10227 Specifies the seek point in seconds, the frames will be output
10228 starting from this seek point, the parameter is evaluated with
10229 @code{av_strtod} so the numerical value may be suffixed by an IS
10230 postfix. Default value is "0".
10233 Specifies the streams to read. Several streams can be specified,
10234 separated by "+". The source will then have as many outputs, in the
10235 same order. The syntax is explained in the ``Stream specifiers''
10236 section in the ffmpeg manual. Two special names, "dv" and "da" specify
10237 respectively the default (best suited) video and audio stream. Default
10238 is "dv", or "da" if the filter is called as "amovie".
10240 @item stream_index, si
10241 Specifies the index of the video stream to read. If the value is -1,
10242 the best suited video stream will be automatically selected. Default
10243 value is "-1". Deprecated. If the filter is called "amovie", it will select
10244 audio instead of video.
10247 Specifies how many times to read the stream in sequence.
10248 If the value is less than 1, the stream will be read again and again.
10249 Default value is "1".
10251 Note that when the movie is looped the source timestamps are not
10252 changed, so it will generate non monotonically increasing timestamps.
10255 This filter allows to overlay a second video on top of main input of
10256 a filtergraph as shown in this graph:
10258 input -----------> deltapts0 --> overlay --> output
10261 movie --> scale--> deltapts1 -------+
10264 @subsection Examples
10268 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
10269 on top of the input labelled as "in":
10271 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
10272 [in] setpts=PTS-STARTPTS [main];
10273 [main][over] overlay=16:16 [out]
10277 Read from a video4linux2 device, and overlay it on top of the input
10280 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
10281 [in] setpts=PTS-STARTPTS [main];
10282 [main][over] overlay=16:16 [out]
10286 Read the first video stream and the audio stream with id 0x81 from
10287 dvd.vob; the video is connected to the pad named "video" and the audio is
10288 connected to the pad named "audio":
10290 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
10294 @c man end MULTIMEDIA SOURCES