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, then 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 the top half of the video is mirrored
29 onto the bottom half of the output video.
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 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", and a filter with no
112 output pads is called a "sink".
114 @anchor{Filtergraph syntax}
115 @section Filtergraph syntax
117 A filtergraph has a textual representation, which is recognized by the
118 @option{-filter}/@option{-vf}/@option{-af} and
119 @option{-filter_complex} options in @command{ffmpeg} and
120 @option{-vf}/@option{-af} in @command{ffplay}, and by the
121 @code{avfilter_graph_parse_ptr()} function defined in
122 @file{libavfilter/avfilter.h}.
124 A filterchain consists of a sequence of connected filters, each one
125 connected to the previous one in the sequence. A filterchain is
126 represented by a list of ","-separated filter descriptions.
128 A filtergraph consists of a sequence of filterchains. A sequence of
129 filterchains is represented by a list of ";"-separated filterchain
132 A filter is represented by a string of the form:
133 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
135 @var{filter_name} is the name of the filter class of which the
136 described filter is an instance of, and has to be the name of one of
137 the filter classes registered in the program.
138 The name of the filter class is optionally followed by a string
141 @var{arguments} is a string which contains the parameters used to
142 initialize the filter instance. It may have one of two forms:
146 A ':'-separated list of @var{key=value} pairs.
149 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
150 the option names in the order they are declared. E.g. the @code{fade} filter
151 declares three options in this order -- @option{type}, @option{start_frame} and
152 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
153 @var{in} is assigned to the option @option{type}, @var{0} to
154 @option{start_frame} and @var{30} to @option{nb_frames}.
157 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
158 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
159 follow the same constraints order of the previous point. The following
160 @var{key=value} pairs can be set in any preferred order.
164 If the option value itself is a list of items (e.g. the @code{format} filter
165 takes a list of pixel formats), the items in the list are usually separated by
168 The list of arguments can be quoted using the character @samp{'} as initial
169 and ending mark, and the character @samp{\} for escaping the characters
170 within the quoted text; otherwise the argument string is considered
171 terminated when the next special character (belonging to the set
172 @samp{[]=;,}) is encountered.
174 The name and arguments of the filter are optionally preceded and
175 followed by a list of link labels.
176 A link label allows one to name a link and associate it to a filter output
177 or input pad. The preceding labels @var{in_link_1}
178 ... @var{in_link_N}, are associated to the filter input pads,
179 the following labels @var{out_link_1} ... @var{out_link_M}, are
180 associated to the output pads.
182 When two link labels with the same name are found in the
183 filtergraph, a link between the corresponding input and output pad is
186 If an output pad is not labelled, it is linked by default to the first
187 unlabelled input pad of the next filter in the filterchain.
188 For example in the filterchain
190 nullsrc, split[L1], [L2]overlay, nullsink
192 the split filter instance has two output pads, and the overlay filter
193 instance two input pads. The first output pad of split is labelled
194 "L1", the first input pad of overlay is labelled "L2", and the second
195 output pad of split is linked to the second input pad of overlay,
196 which are both unlabelled.
198 In a filter description, if the input label of the first filter is not
199 specified, "in" is assumed; if the output label of the last filter is not
200 specified, "out" is assumed.
202 In a complete filterchain all the unlabelled filter input and output
203 pads must be connected. A filtergraph is considered valid if all the
204 filter input and output pads of all the filterchains are connected.
206 Libavfilter will automatically insert @ref{scale} filters where format
207 conversion is required. It is possible to specify swscale flags
208 for those automatically inserted scalers by prepending
209 @code{sws_flags=@var{flags};}
210 to the filtergraph description.
212 Here is a BNF description of the filtergraph syntax:
214 @var{NAME} ::= sequence of alphanumeric characters and '_'
215 @var{LINKLABEL} ::= "[" @var{NAME} "]"
216 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
217 @var{FILTER_ARGUMENTS} ::= sequence of chars (possibly quoted)
218 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
219 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
220 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
223 @section Notes on filtergraph escaping
225 Filtergraph description composition entails several levels of
226 escaping. See @ref{quoting_and_escaping,,the "Quoting and escaping"
227 section in the ffmpeg-utils(1) manual,ffmpeg-utils} for more
228 information about the employed escaping procedure.
230 A first level escaping affects the content of each filter option
231 value, which may contain the special character @code{:} used to
232 separate values, or one of the escaping characters @code{\'}.
234 A second level escaping affects the whole filter description, which
235 may contain the escaping characters @code{\'} or the special
236 characters @code{[],;} used by the filtergraph description.
238 Finally, when you specify a filtergraph on a shell commandline, you
239 need to perform a third level escaping for the shell special
240 characters contained within it.
242 For example, consider the following string to be embedded in
243 the @ref{drawtext} filter description @option{text} value:
245 this is a 'string': may contain one, or more, special characters
248 This string contains the @code{'} special escaping character, and the
249 @code{:} special character, so it needs to be escaped in this way:
251 text=this is a \'string\'\: may contain one, or more, special characters
254 A second level of escaping is required when embedding the filter
255 description in a filtergraph description, in order to escape all the
256 filtergraph special characters. Thus the example above becomes:
258 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
260 (note that in addition to the @code{\'} escaping special characters,
261 also @code{,} needs to be escaped).
263 Finally an additional level of escaping is needed when writing the
264 filtergraph description in a shell command, which depends on the
265 escaping rules of the adopted shell. For example, assuming that
266 @code{\} is special and needs to be escaped with another @code{\}, the
267 previous string will finally result in:
269 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
272 @chapter Timeline editing
274 Some filters support a generic @option{enable} option. For the filters
275 supporting timeline editing, this option can be set to an expression which is
276 evaluated before sending a frame to the filter. If the evaluation is non-zero,
277 the filter will be enabled, otherwise the frame will be sent unchanged to the
278 next filter in the filtergraph.
280 The expression accepts the following values:
283 timestamp expressed in seconds, NAN if the input timestamp is unknown
286 sequential number of the input frame, starting from 0
289 the position in the file of the input frame, NAN if unknown
293 width and height of the input frame if video
296 Additionally, these filters support an @option{enable} command that can be used
297 to re-define the expression.
299 Like any other filtering option, the @option{enable} option follows the same
302 For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3
303 minutes, and a @ref{curves} filter starting at 3 seconds:
305 smartblur = enable='between(t,10,3*60)',
306 curves = enable='gte(t,3)' : preset=cross_process
309 @c man end FILTERGRAPH DESCRIPTION
311 @chapter Audio Filters
312 @c man begin AUDIO FILTERS
314 When you configure your FFmpeg build, you can disable any of the
315 existing filters using @code{--disable-filters}.
316 The configure output will show the audio filters included in your
319 Below is a description of the currently available audio filters.
323 Apply cross fade from one input audio stream to another input audio stream.
324 The cross fade is applied for specified duration near the end of first stream.
326 The filter accepts the following options:
330 Specify the number of samples for which the cross fade effect has to last.
331 At the end of the cross fade effect the first input audio will be completely
332 silent. Default is 44100.
335 Specify the duration of the cross fade effect. See
336 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
337 for the accepted syntax.
338 By default the duration is determined by @var{nb_samples}.
339 If set this option is used instead of @var{nb_samples}.
342 Should first stream end overlap with second stream start. Default is enabled.
345 Set curve for cross fade transition for first stream.
348 Set curve for cross fade transition for second stream.
350 For description of available curve types see @ref{afade} filter description.
357 Cross fade from one input to another:
359 ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac
363 Cross fade from one input to another but without overlapping:
365 ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac
371 Delay one or more audio channels.
373 Samples in delayed channel are filled with silence.
375 The filter accepts the following option:
379 Set list of delays in milliseconds for each channel separated by '|'.
380 At least one delay greater than 0 should be provided.
381 Unused delays will be silently ignored. If number of given delays is
382 smaller than number of channels all remaining channels will not be delayed.
389 Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
390 the second channel (and any other channels that may be present) unchanged.
398 Apply echoing to the input audio.
400 Echoes are reflected sound and can occur naturally amongst mountains
401 (and sometimes large buildings) when talking or shouting; digital echo
402 effects emulate this behaviour and are often used to help fill out the
403 sound of a single instrument or vocal. The time difference between the
404 original signal and the reflection is the @code{delay}, and the
405 loudness of the reflected signal is the @code{decay}.
406 Multiple echoes can have different delays and decays.
408 A description of the accepted parameters follows.
412 Set input gain of reflected signal. Default is @code{0.6}.
415 Set output gain of reflected signal. Default is @code{0.3}.
418 Set list of time intervals in milliseconds between original signal and reflections
419 separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}.
420 Default is @code{1000}.
423 Set list of loudnesses of reflected signals separated by '|'.
424 Allowed range for each @code{decay} is @code{(0 - 1.0]}.
425 Default is @code{0.5}.
432 Make it sound as if there are twice as many instruments as are actually playing:
434 aecho=0.8:0.88:60:0.4
438 If delay is very short, then it sound like a (metallic) robot playing music:
444 A longer delay will sound like an open air concert in the mountains:
446 aecho=0.8:0.9:1000:0.3
450 Same as above but with one more mountain:
452 aecho=0.8:0.9:1000|1800:0.3|0.25
458 Modify an audio signal according to the specified expressions.
460 This filter accepts one or more expressions (one for each channel),
461 which are evaluated and used to modify a corresponding audio signal.
463 It accepts the following parameters:
467 Set the '|'-separated expressions list for each separate channel. If
468 the number of input channels is greater than the number of
469 expressions, the last specified expression is used for the remaining
472 @item channel_layout, c
473 Set output channel layout. If not specified, the channel layout is
474 specified by the number of expressions. If set to @samp{same}, it will
475 use by default the same input channel layout.
478 Each expression in @var{exprs} can contain the following constants and functions:
482 channel number of the current expression
485 number of the evaluated sample, starting from 0
491 time of the evaluated sample expressed in seconds
494 @item nb_out_channels
495 input and output number of channels
498 the value of input channel with number @var{CH}
501 Note: this filter is slow. For faster processing you should use a
510 aeval=val(ch)/2:c=same
514 Invert phase of the second channel:
523 Apply fade-in/out effect to input audio.
525 A description of the accepted parameters follows.
529 Specify the effect type, can be either @code{in} for fade-in, or
530 @code{out} for a fade-out effect. Default is @code{in}.
532 @item start_sample, ss
533 Specify the number of the start sample for starting to apply the fade
534 effect. Default is 0.
537 Specify the number of samples for which the fade effect has to last. At
538 the end of the fade-in effect the output audio will have the same
539 volume as the input audio, at the end of the fade-out transition
540 the output audio will be silence. Default is 44100.
543 Specify the start time of the fade effect. Default is 0.
544 The value must be specified as a time duration; see
545 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
546 for the accepted syntax.
547 If set this option is used instead of @var{start_sample}.
550 Specify the duration of the fade effect. See
551 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
552 for the accepted syntax.
553 At the end of the fade-in effect the output audio will have the same
554 volume as the input audio, at the end of the fade-out transition
555 the output audio will be silence.
556 By default the duration is determined by @var{nb_samples}.
557 If set this option is used instead of @var{nb_samples}.
560 Set curve for fade transition.
562 It accepts the following values:
565 select triangular, linear slope (default)
567 select quarter of sine wave
569 select half of sine wave
571 select exponential sine wave
575 select inverted parabola
589 select inverted quarter of sine wave
591 select inverted half of sine wave
593 select double-exponential seat
595 select double-exponential sigmoid
603 Fade in first 15 seconds of audio:
609 Fade out last 25 seconds of a 900 seconds audio:
611 afade=t=out:st=875:d=25
618 Set output format constraints for the input audio. The framework will
619 negotiate the most appropriate format to minimize conversions.
621 It accepts the following parameters:
625 A '|'-separated list of requested sample formats.
628 A '|'-separated list of requested sample rates.
630 @item channel_layouts
631 A '|'-separated list of requested channel layouts.
633 See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils}
634 for the required syntax.
637 If a parameter is omitted, all values are allowed.
639 Force the output to either unsigned 8-bit or signed 16-bit stereo
641 aformat=sample_fmts=u8|s16:channel_layouts=stereo
646 The limiter prevents input signal from raising over a desired threshold.
647 This limiter uses lookahead technology to prevent your signal from distorting.
648 It means that there is a small delay after signal is processed. Keep in mind
649 that the delay it produces is the attack time you set.
651 The filter accepts the following options:
655 Don't let signals above this level pass the limiter. The removed amplitude is
656 added automatically. Default is 1.
659 The limiter will reach its attenuation level in this amount of time in
660 milliseconds. Default is 5 milliseconds.
663 Come back from limiting to attenuation 1.0 in this amount of milliseconds.
664 Default is 50 milliseconds.
667 When gain reduction is always needed ASC takes care of releasing to an
668 average reduction level rather than reaching a reduction of 0 in the release
672 Select how much the release time is affected by ASC, 0 means nearly no changes
673 in release time while 1 produces higher release times.
676 Depending on picked setting it is recommended to upsample input 2x or 4x times
677 with @ref{aresample} before applying this filter.
681 Apply a two-pole all-pass filter with central frequency (in Hz)
682 @var{frequency}, and filter-width @var{width}.
683 An all-pass filter changes the audio's frequency to phase relationship
684 without changing its frequency to amplitude relationship.
686 The filter accepts the following options:
693 Set method to specify band-width of filter.
706 Specify the band-width of a filter in width_type units.
712 Merge two or more audio streams into a single multi-channel stream.
714 The filter accepts the following options:
719 Set the number of inputs. Default is 2.
723 If the channel layouts of the inputs are disjoint, and therefore compatible,
724 the channel layout of the output will be set accordingly and the channels
725 will be reordered as necessary. If the channel layouts of the inputs are not
726 disjoint, the output will have all the channels of the first input then all
727 the channels of the second input, in that order, and the channel layout of
728 the output will be the default value corresponding to the total number of
731 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
732 is FC+BL+BR, then the output will be in 5.1, with the channels in the
733 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
734 first input, b1 is the first channel of the second input).
736 On the other hand, if both input are in stereo, the output channels will be
737 in the default order: a1, a2, b1, b2, and the channel layout will be
738 arbitrarily set to 4.0, which may or may not be the expected value.
740 All inputs must have the same sample rate, and format.
742 If inputs do not have the same duration, the output will stop with the
749 Merge two mono files into a stereo stream:
751 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
755 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
757 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
763 Mixes multiple audio inputs into a single output.
765 Note that this filter only supports float samples (the @var{amerge}
766 and @var{pan} audio filters support many formats). If the @var{amix}
767 input has integer samples then @ref{aresample} will be automatically
768 inserted to perform the conversion to float samples.
772 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
774 will mix 3 input audio streams to a single output with the same duration as the
775 first input and a dropout transition time of 3 seconds.
777 It accepts the following parameters:
781 The number of inputs. If unspecified, it defaults to 2.
784 How to determine the end-of-stream.
788 The duration of the longest input. (default)
791 The duration of the shortest input.
794 The duration of the first input.
798 @item dropout_transition
799 The transition time, in seconds, for volume renormalization when an input
800 stream ends. The default value is 2 seconds.
806 Pass the audio source unchanged to the output.
810 Pad the end of an audio stream with silence.
812 This can be used together with @command{ffmpeg} @option{-shortest} to
813 extend audio streams to the same length as the video stream.
815 A description of the accepted options follows.
819 Set silence packet size. Default value is 4096.
822 Set the number of samples of silence to add to the end. After the
823 value is reached, the stream is terminated. This option is mutually
824 exclusive with @option{whole_len}.
827 Set the minimum total number of samples in the output audio stream. If
828 the value is longer than the input audio length, silence is added to
829 the end, until the value is reached. This option is mutually exclusive
830 with @option{pad_len}.
833 If neither the @option{pad_len} nor the @option{whole_len} option is
834 set, the filter will add silence to the end of the input stream
841 Add 1024 samples of silence to the end of the input:
847 Make sure the audio output will contain at least 10000 samples, pad
848 the input with silence if required:
854 Use @command{ffmpeg} to pad the audio input with silence, so that the
855 video stream will always result the shortest and will be converted
856 until the end in the output file when using the @option{shortest}
859 ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT
864 Add a phasing effect to the input audio.
866 A phaser filter creates series of peaks and troughs in the frequency spectrum.
867 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
869 A description of the accepted parameters follows.
873 Set input gain. Default is 0.4.
876 Set output gain. Default is 0.74
879 Set delay in milliseconds. Default is 3.0.
882 Set decay. Default is 0.4.
885 Set modulation speed in Hz. Default is 0.5.
888 Set modulation type. Default is triangular.
890 It accepts the following values:
900 Resample the input audio to the specified parameters, using the
901 libswresample library. If none are specified then the filter will
902 automatically convert between its input and output.
904 This filter is also able to stretch/squeeze the audio data to make it match
905 the timestamps or to inject silence / cut out audio to make it match the
906 timestamps, do a combination of both or do neither.
908 The filter accepts the syntax
909 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
910 expresses a sample rate and @var{resampler_options} is a list of
911 @var{key}=@var{value} pairs, separated by ":". See the
912 ffmpeg-resampler manual for the complete list of supported options.
918 Resample the input audio to 44100Hz:
924 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
925 samples per second compensation:
931 @section asetnsamples
933 Set the number of samples per each output audio frame.
935 The last output packet may contain a different number of samples, as
936 the filter will flush all the remaining samples when the input audio
939 The filter accepts the following options:
943 @item nb_out_samples, n
944 Set the number of frames per each output audio frame. The number is
945 intended as the number of samples @emph{per each channel}.
946 Default value is 1024.
949 If set to 1, the filter will pad the last audio frame with zeroes, so
950 that the last frame will contain the same number of samples as the
951 previous ones. Default value is 1.
954 For example, to set the number of per-frame samples to 1234 and
955 disable padding for the last frame, use:
957 asetnsamples=n=1234:p=0
962 Set the sample rate without altering the PCM data.
963 This will result in a change of speed and pitch.
965 The filter accepts the following options:
969 Set the output sample rate. Default is 44100 Hz.
974 Show a line containing various information for each input audio frame.
975 The input audio is not modified.
977 The shown line contains a sequence of key/value pairs of the form
978 @var{key}:@var{value}.
980 The following values are shown in the output:
984 The (sequential) number of the input frame, starting from 0.
987 The presentation timestamp of the input frame, in time base units; the time base
988 depends on the filter input pad, and is usually 1/@var{sample_rate}.
991 The presentation timestamp of the input frame in seconds.
994 position of the frame in the input stream, -1 if this information in
995 unavailable and/or meaningless (for example in case of synthetic audio)
1004 The sample rate for the audio frame.
1007 The number of samples (per channel) in the frame.
1010 The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
1011 audio, the data is treated as if all the planes were concatenated.
1013 @item plane_checksums
1014 A list of Adler-32 checksums for each data plane.
1020 Display time domain statistical information about the audio channels.
1021 Statistics are calculated and displayed for each audio channel and,
1022 where applicable, an overall figure is also given.
1024 It accepts the following option:
1027 Short window length in seconds, used for peak and trough RMS measurement.
1028 Default is @code{0.05} (50 milliseconds). Allowed range is @code{[0.1 - 10]}.
1032 Set metadata injection. All the metadata keys are prefixed with @code{lavfi.astats.X},
1033 where @code{X} is channel number starting from 1 or string @code{Overall}. Default is
1036 Available keys for each channel are:
1067 For example full key look like this @code{lavfi.astats.1.DC_offset} or
1068 this @code{lavfi.astats.Overall.Peak_count}.
1070 For description what each key means read bellow.
1073 Set number of frame after which stats are going to be recalculated.
1074 Default is disabled.
1077 A description of each shown parameter follows:
1081 Mean amplitude displacement from zero.
1084 Minimal sample level.
1087 Maximal sample level.
1089 @item Min difference
1090 Minimal difference between two consecutive samples.
1092 @item Max difference
1093 Maximal difference between two consecutive samples.
1095 @item Mean difference
1096 Mean difference between two consecutive samples.
1097 The average of each difference between two consecutive samples.
1101 Standard peak and RMS level measured in dBFS.
1105 Peak and trough values for RMS level measured over a short window.
1108 Standard ratio of peak to RMS level (note: not in dB).
1111 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
1112 (i.e. either @var{Min level} or @var{Max level}).
1115 Number of occasions (not the number of samples) that the signal attained either
1116 @var{Min level} or @var{Max level}.
1119 Overall bit depth of audio. Number of bits used for each sample.
1122 @section astreamsync
1124 Forward two audio streams and control the order the buffers are forwarded.
1126 The filter accepts the following options:
1130 Set the expression deciding which stream should be
1131 forwarded next: if the result is negative, the first stream is forwarded; if
1132 the result is positive or zero, the second stream is forwarded. It can use
1133 the following variables:
1137 number of buffers forwarded so far on each stream
1139 number of samples forwarded so far on each stream
1141 current timestamp of each stream
1144 The default value is @code{t1-t2}, which means to always forward the stream
1145 that has a smaller timestamp.
1148 @subsection Examples
1150 Stress-test @code{amerge} by randomly sending buffers on the wrong
1151 input, while avoiding too much of a desynchronization:
1153 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1154 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1160 Synchronize audio data with timestamps by squeezing/stretching it and/or
1161 dropping samples/adding silence when needed.
1163 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1165 It accepts the following parameters:
1169 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1170 by default. When disabled, time gaps are covered with silence.
1173 The minimum difference between timestamps and audio data (in seconds) to trigger
1174 adding/dropping samples. The default value is 0.1. If you get an imperfect
1175 sync with this filter, try setting this parameter to 0.
1178 The maximum compensation in samples per second. Only relevant with compensate=1.
1179 The default value is 500.
1182 Assume that the first PTS should be this value. The time base is 1 / sample
1183 rate. This allows for padding/trimming at the start of the stream. By default,
1184 no assumption is made about the first frame's expected PTS, so no padding or
1185 trimming is done. For example, this could be set to 0 to pad the beginning with
1186 silence if an audio stream starts after the video stream or to trim any samples
1187 with a negative PTS due to encoder delay.
1195 The filter accepts exactly one parameter, the audio tempo. If not
1196 specified then the filter will assume nominal 1.0 tempo. Tempo must
1197 be in the [0.5, 2.0] range.
1199 @subsection Examples
1203 Slow down audio to 80% tempo:
1209 To speed up audio to 125% tempo:
1217 Trim the input so that the output contains one continuous subpart of the input.
1219 It accepts the following parameters:
1222 Timestamp (in seconds) of the start of the section to keep. I.e. the audio
1223 sample with the timestamp @var{start} will be the first sample in the output.
1226 Specify time of the first audio sample that will be dropped, i.e. the
1227 audio sample immediately preceding the one with the timestamp @var{end} will be
1228 the last sample in the output.
1231 Same as @var{start}, except this option sets the start timestamp in samples
1235 Same as @var{end}, except this option sets the end timestamp in samples instead
1239 The maximum duration of the output in seconds.
1242 The number of the first sample that should be output.
1245 The number of the first sample that should be dropped.
1248 @option{start}, @option{end}, and @option{duration} are expressed as time
1249 duration specifications; see
1250 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
1252 Note that the first two sets of the start/end options and the @option{duration}
1253 option look at the frame timestamp, while the _sample options simply count the
1254 samples that pass through the filter. So start/end_pts and start/end_sample will
1255 give different results when the timestamps are wrong, inexact or do not start at
1256 zero. Also note that this filter does not modify the timestamps. If you wish
1257 to have the output timestamps start at zero, insert the asetpts filter after the
1260 If multiple start or end options are set, this filter tries to be greedy and
1261 keep all samples that match at least one of the specified constraints. To keep
1262 only the part that matches all the constraints at once, chain multiple atrim
1265 The defaults are such that all the input is kept. So it is possible to set e.g.
1266 just the end values to keep everything before the specified time.
1271 Drop everything except the second minute of input:
1273 ffmpeg -i INPUT -af atrim=60:120
1277 Keep only the first 1000 samples:
1279 ffmpeg -i INPUT -af atrim=end_sample=1000
1286 Apply a two-pole Butterworth band-pass filter with central
1287 frequency @var{frequency}, and (3dB-point) band-width width.
1288 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1289 instead of the default: constant 0dB peak gain.
1290 The filter roll off at 6dB per octave (20dB per decade).
1292 The filter accepts the following options:
1296 Set the filter's central frequency. Default is @code{3000}.
1299 Constant skirt gain if set to 1. Defaults to 0.
1302 Set method to specify band-width of filter.
1315 Specify the band-width of a filter in width_type units.
1320 Apply a two-pole Butterworth band-reject filter with central
1321 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1322 The filter roll off at 6dB per octave (20dB per decade).
1324 The filter accepts the following options:
1328 Set the filter's central frequency. Default is @code{3000}.
1331 Set method to specify band-width of filter.
1344 Specify the band-width of a filter in width_type units.
1349 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1350 shelving filter with a response similar to that of a standard
1351 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1353 The filter accepts the following options:
1357 Give the gain at 0 Hz. Its useful range is about -20
1358 (for a large cut) to +20 (for a large boost).
1359 Beware of clipping when using a positive gain.
1362 Set the filter's central frequency and so can be used
1363 to extend or reduce the frequency range to be boosted or cut.
1364 The default value is @code{100} Hz.
1367 Set method to specify band-width of filter.
1380 Determine how steep is the filter's shelf transition.
1385 Apply a biquad IIR filter with the given coefficients.
1386 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1387 are the numerator and denominator coefficients respectively.
1390 Bauer stereo to binaural transformation, which improves headphone listening of
1391 stereo audio records.
1393 It accepts the following parameters:
1397 Pre-defined crossfeed level.
1401 Default level (fcut=700, feed=50).
1404 Chu Moy circuit (fcut=700, feed=60).
1407 Jan Meier circuit (fcut=650, feed=95).
1412 Cut frequency (in Hz).
1421 Remap input channels to new locations.
1423 It accepts the following parameters:
1425 @item channel_layout
1426 The channel layout of the output stream.
1429 Map channels from input to output. The argument is a '|'-separated list of
1430 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1431 @var{in_channel} form. @var{in_channel} can be either the name of the input
1432 channel (e.g. FL for front left) or its index in the input channel layout.
1433 @var{out_channel} is the name of the output channel or its index in the output
1434 channel layout. If @var{out_channel} is not given then it is implicitly an
1435 index, starting with zero and increasing by one for each mapping.
1438 If no mapping is present, the filter will implicitly map input channels to
1439 output channels, preserving indices.
1441 For example, assuming a 5.1+downmix input MOV file,
1443 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1445 will create an output WAV file tagged as stereo from the downmix channels of
1448 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1450 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
1453 @section channelsplit
1455 Split each channel from an input audio stream into a separate output stream.
1457 It accepts the following parameters:
1459 @item channel_layout
1460 The channel layout of the input stream. The default is "stereo".
1463 For example, assuming a stereo input MP3 file,
1465 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1467 will create an output Matroska file with two audio streams, one containing only
1468 the left channel and the other the right channel.
1470 Split a 5.1 WAV file into per-channel files:
1472 ffmpeg -i in.wav -filter_complex
1473 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1474 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1475 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1480 Add a chorus effect to the audio.
1482 Can make a single vocal sound like a chorus, but can also be applied to instrumentation.
1484 Chorus resembles an echo effect with a short delay, but whereas with echo the delay is
1485 constant, with chorus, it is varied using using sinusoidal or triangular modulation.
1486 The modulation depth defines the range the modulated delay is played before or after
1487 the delay. Hence the delayed sound will sound slower or faster, that is the delayed
1488 sound tuned around the original one, like in a chorus where some vocals are slightly
1491 It accepts the following parameters:
1494 Set input gain. Default is 0.4.
1497 Set output gain. Default is 0.4.
1500 Set delays. A typical delay is around 40ms to 60ms.
1512 @subsection Examples
1518 chorus=0.7:0.9:55:0.4:0.25:2
1524 chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3
1528 Fuller sounding chorus with three delays:
1530 chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3
1535 Compress or expand the audio's dynamic range.
1537 It accepts the following parameters:
1543 A list of times in seconds for each channel over which the instantaneous level
1544 of the input signal is averaged to determine its volume. @var{attacks} refers to
1545 increase of volume and @var{decays} refers to decrease of volume. For most
1546 situations, the attack time (response to the audio getting louder) should be
1547 shorter than the decay time, because the human ear is more sensitive to sudden
1548 loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
1549 a typical value for decay is 0.8 seconds.
1550 If specified number of attacks & decays is lower than number of channels, the last
1551 set attack/decay will be used for all remaining channels.
1554 A list of points for the transfer function, specified in dB relative to the
1555 maximum possible signal amplitude. Each key points list must be defined using
1556 the following syntax: @code{x0/y0|x1/y1|x2/y2|....} or
1557 @code{x0/y0 x1/y1 x2/y2 ....}
1559 The input values must be in strictly increasing order but the transfer function
1560 does not have to be monotonically rising. The point @code{0/0} is assumed but
1561 may be overridden (by @code{0/out-dBn}). Typical values for the transfer
1562 function are @code{-70/-70|-60/-20}.
1565 Set the curve radius in dB for all joints. It defaults to 0.01.
1568 Set the additional gain in dB to be applied at all points on the transfer
1569 function. This allows for easy adjustment of the overall gain.
1573 Set an initial volume, in dB, to be assumed for each channel when filtering
1574 starts. This permits the user to supply a nominal level initially, so that, for
1575 example, a very large gain is not applied to initial signal levels before the
1576 companding has begun to operate. A typical value for audio which is initially
1577 quiet is -90 dB. It defaults to 0.
1580 Set a delay, in seconds. The input audio is analyzed immediately, but audio is
1581 delayed before being fed to the volume adjuster. Specifying a delay
1582 approximately equal to the attack/decay times allows the filter to effectively
1583 operate in predictive rather than reactive mode. It defaults to 0.
1587 @subsection Examples
1591 Make music with both quiet and loud passages suitable for listening to in a
1594 compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
1597 Another example for audio with whisper and explosion parts:
1599 compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0
1603 A noise gate for when the noise is at a lower level than the signal:
1605 compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
1609 Here is another noise gate, this time for when the noise is at a higher level
1610 than the signal (making it, in some ways, similar to squelch):
1612 compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
1617 Apply a DC shift to the audio.
1619 This can be useful to remove a DC offset (caused perhaps by a hardware problem
1620 in the recording chain) from the audio. The effect of a DC offset is reduced
1621 headroom and hence volume. The @ref{astats} filter can be used to determine if
1622 a signal has a DC offset.
1626 Set the DC shift, allowed range is [-1, 1]. It indicates the amount to shift
1630 Optional. It should have a value much less than 1 (e.g. 0.05 or 0.02) and is
1631 used to prevent clipping.
1635 Dynamic Audio Normalizer.
1637 This filter applies a certain amount of gain to the input audio in order
1638 to bring its peak magnitude to a target level (e.g. 0 dBFS). However, in
1639 contrast to more "simple" normalization algorithms, the Dynamic Audio
1640 Normalizer *dynamically* re-adjusts the gain factor to the input audio.
1641 This allows for applying extra gain to the "quiet" sections of the audio
1642 while avoiding distortions or clipping the "loud" sections. In other words:
1643 The Dynamic Audio Normalizer will "even out" the volume of quiet and loud
1644 sections, in the sense that the volume of each section is brought to the
1645 same target level. Note, however, that the Dynamic Audio Normalizer achieves
1646 this goal *without* applying "dynamic range compressing". It will retain 100%
1647 of the dynamic range *within* each section of the audio file.
1651 Set the frame length in milliseconds. In range from 10 to 8000 milliseconds.
1652 Default is 500 milliseconds.
1653 The Dynamic Audio Normalizer processes the input audio in small chunks,
1654 referred to as frames. This is required, because a peak magnitude has no
1655 meaning for just a single sample value. Instead, we need to determine the
1656 peak magnitude for a contiguous sequence of sample values. While a "standard"
1657 normalizer would simply use the peak magnitude of the complete file, the
1658 Dynamic Audio Normalizer determines the peak magnitude individually for each
1659 frame. The length of a frame is specified in milliseconds. By default, the
1660 Dynamic Audio Normalizer uses a frame length of 500 milliseconds, which has
1661 been found to give good results with most files.
1662 Note that the exact frame length, in number of samples, will be determined
1663 automatically, based on the sampling rate of the individual input audio file.
1666 Set the Gaussian filter window size. In range from 3 to 301, must be odd
1667 number. Default is 31.
1668 Probably the most important parameter of the Dynamic Audio Normalizer is the
1669 @code{window size} of the Gaussian smoothing filter. The filter's window size
1670 is specified in frames, centered around the current frame. For the sake of
1671 simplicity, this must be an odd number. Consequently, the default value of 31
1672 takes into account the current frame, as well as the 15 preceding frames and
1673 the 15 subsequent frames. Using a larger window results in a stronger
1674 smoothing effect and thus in less gain variation, i.e. slower gain
1675 adaptation. Conversely, using a smaller window results in a weaker smoothing
1676 effect and thus in more gain variation, i.e. faster gain adaptation.
1677 In other words, the more you increase this value, the more the Dynamic Audio
1678 Normalizer will behave like a "traditional" normalization filter. On the
1679 contrary, the more you decrease this value, the more the Dynamic Audio
1680 Normalizer will behave like a dynamic range compressor.
1683 Set the target peak value. This specifies the highest permissible magnitude
1684 level for the normalized audio input. This filter will try to approach the
1685 target peak magnitude as closely as possible, but at the same time it also
1686 makes sure that the normalized signal will never exceed the peak magnitude.
1687 A frame's maximum local gain factor is imposed directly by the target peak
1688 magnitude. The default value is 0.95 and thus leaves a headroom of 5%*.
1689 It is not recommended to go above this value.
1692 Set the maximum gain factor. In range from 1.0 to 100.0. Default is 10.0.
1693 The Dynamic Audio Normalizer determines the maximum possible (local) gain
1694 factor for each input frame, i.e. the maximum gain factor that does not
1695 result in clipping or distortion. The maximum gain factor is determined by
1696 the frame's highest magnitude sample. However, the Dynamic Audio Normalizer
1697 additionally bounds the frame's maximum gain factor by a predetermined
1698 (global) maximum gain factor. This is done in order to avoid excessive gain
1699 factors in "silent" or almost silent frames. By default, the maximum gain
1700 factor is 10.0, For most inputs the default value should be sufficient and
1701 it usually is not recommended to increase this value. Though, for input
1702 with an extremely low overall volume level, it may be necessary to allow even
1703 higher gain factors. Note, however, that the Dynamic Audio Normalizer does
1704 not simply apply a "hard" threshold (i.e. cut off values above the threshold).
1705 Instead, a "sigmoid" threshold function will be applied. This way, the
1706 gain factors will smoothly approach the threshold value, but never exceed that
1710 Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 - disabled.
1711 By default, the Dynamic Audio Normalizer performs "peak" normalization.
1712 This means that the maximum local gain factor for each frame is defined
1713 (only) by the frame's highest magnitude sample. This way, the samples can
1714 be amplified as much as possible without exceeding the maximum signal
1715 level, i.e. without clipping. Optionally, however, the Dynamic Audio
1716 Normalizer can also take into account the frame's root mean square,
1717 abbreviated RMS. In electrical engineering, the RMS is commonly used to
1718 determine the power of a time-varying signal. It is therefore considered
1719 that the RMS is a better approximation of the "perceived loudness" than
1720 just looking at the signal's peak magnitude. Consequently, by adjusting all
1721 frames to a constant RMS value, a uniform "perceived loudness" can be
1722 established. If a target RMS value has been specified, a frame's local gain
1723 factor is defined as the factor that would result in exactly that RMS value.
1724 Note, however, that the maximum local gain factor is still restricted by the
1725 frame's highest magnitude sample, in order to prevent clipping.
1728 Enable channels coupling. By default is enabled.
1729 By default, the Dynamic Audio Normalizer will amplify all channels by the same
1730 amount. This means the same gain factor will be applied to all channels, i.e.
1731 the maximum possible gain factor is determined by the "loudest" channel.
1732 However, in some recordings, it may happen that the volume of the different
1733 channels is uneven, e.g. one channel may be "quieter" than the other one(s).
1734 In this case, this option can be used to disable the channel coupling. This way,
1735 the gain factor will be determined independently for each channel, depending
1736 only on the individual channel's highest magnitude sample. This allows for
1737 harmonizing the volume of the different channels.
1740 Enable DC bias correction. By default is disabled.
1741 An audio signal (in the time domain) is a sequence of sample values.
1742 In the Dynamic Audio Normalizer these sample values are represented in the
1743 -1.0 to 1.0 range, regardless of the original input format. Normally, the
1744 audio signal, or "waveform", should be centered around the zero point.
1745 That means if we calculate the mean value of all samples in a file, or in a
1746 single frame, then the result should be 0.0 or at least very close to that
1747 value. If, however, there is a significant deviation of the mean value from
1748 0.0, in either positive or negative direction, this is referred to as a
1749 DC bias or DC offset. Since a DC bias is clearly undesirable, the Dynamic
1750 Audio Normalizer provides optional DC bias correction.
1751 With DC bias correction enabled, the Dynamic Audio Normalizer will determine
1752 the mean value, or "DC correction" offset, of each input frame and subtract
1753 that value from all of the frame's sample values which ensures those samples
1754 are centered around 0.0 again. Also, in order to avoid "gaps" at the frame
1755 boundaries, the DC correction offset values will be interpolated smoothly
1756 between neighbouring frames.
1759 Enable alternative boundary mode. By default is disabled.
1760 The Dynamic Audio Normalizer takes into account a certain neighbourhood
1761 around each frame. This includes the preceding frames as well as the
1762 subsequent frames. However, for the "boundary" frames, located at the very
1763 beginning and at the very end of the audio file, not all neighbouring
1764 frames are available. In particular, for the first few frames in the audio
1765 file, the preceding frames are not known. And, similarly, for the last few
1766 frames in the audio file, the subsequent frames are not known. Thus, the
1767 question arises which gain factors should be assumed for the missing frames
1768 in the "boundary" region. The Dynamic Audio Normalizer implements two modes
1769 to deal with this situation. The default boundary mode assumes a gain factor
1770 of exactly 1.0 for the missing frames, resulting in a smooth "fade in" and
1771 "fade out" at the beginning and at the end of the input, respectively.
1774 Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
1775 By default, the Dynamic Audio Normalizer does not apply "traditional"
1776 compression. This means that signal peaks will not be pruned and thus the
1777 full dynamic range will be retained within each local neighbourhood. However,
1778 in some cases it may be desirable to combine the Dynamic Audio Normalizer's
1779 normalization algorithm with a more "traditional" compression.
1780 For this purpose, the Dynamic Audio Normalizer provides an optional compression
1781 (thresholding) function. If (and only if) the compression feature is enabled,
1782 all input frames will be processed by a soft knee thresholding function prior
1783 to the actual normalization process. Put simply, the thresholding function is
1784 going to prune all samples whose magnitude exceeds a certain threshold value.
1785 However, the Dynamic Audio Normalizer does not simply apply a fixed threshold
1786 value. Instead, the threshold value will be adjusted for each individual
1788 In general, smaller parameters result in stronger compression, and vice versa.
1789 Values below 3.0 are not recommended, because audible distortion may appear.
1794 Make audio easier to listen to on headphones.
1796 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1797 so that when listened to on headphones the stereo image is moved from
1798 inside your head (standard for headphones) to outside and in front of
1799 the listener (standard for speakers).
1805 Apply a two-pole peaking equalisation (EQ) filter. With this
1806 filter, the signal-level at and around a selected frequency can
1807 be increased or decreased, whilst (unlike bandpass and bandreject
1808 filters) that at all other frequencies is unchanged.
1810 In order to produce complex equalisation curves, this filter can
1811 be given several times, each with a different central frequency.
1813 The filter accepts the following options:
1817 Set the filter's central frequency in Hz.
1820 Set method to specify band-width of filter.
1833 Specify the band-width of a filter in width_type units.
1836 Set the required gain or attenuation in dB.
1837 Beware of clipping when using a positive gain.
1840 @subsection Examples
1843 Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
1845 equalizer=f=1000:width_type=h:width=200:g=-10
1849 Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
1851 equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
1855 @section extrastereo
1857 Linearly increases the difference between left and right channels which
1858 adds some sort of "live" effect to playback.
1860 The filter accepts the following option:
1864 Sets the difference coefficient (default: 2.5). 0.0 means mono sound
1865 (average of both channels), with 1.0 sound will be unchanged, with
1866 -1.0 left and right channels will be swapped.
1869 Enable clipping. By default is enabled.
1873 Apply a flanging effect to the audio.
1875 The filter accepts the following options:
1879 Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
1882 Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2.
1885 Set percentage regeneration (delayed signal feedback). Range from -95 to 95.
1889 Set percentage of delayed signal mixed with original. Range from 0 to 100.
1890 Default value is 71.
1893 Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
1896 Set swept wave shape, can be @var{triangular} or @var{sinusoidal}.
1897 Default value is @var{sinusoidal}.
1900 Set swept wave percentage-shift for multi channel. Range from 0 to 100.
1901 Default value is 25.
1904 Set delay-line interpolation, @var{linear} or @var{quadratic}.
1905 Default is @var{linear}.
1910 Apply a high-pass filter with 3dB point frequency.
1911 The filter can be either single-pole, or double-pole (the default).
1912 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1914 The filter accepts the following options:
1918 Set frequency in Hz. Default is 3000.
1921 Set number of poles. Default is 2.
1924 Set method to specify band-width of filter.
1937 Specify the band-width of a filter in width_type units.
1938 Applies only to double-pole filter.
1939 The default is 0.707q and gives a Butterworth response.
1944 Join multiple input streams into one multi-channel stream.
1946 It accepts the following parameters:
1950 The number of input streams. It defaults to 2.
1952 @item channel_layout
1953 The desired output channel layout. It defaults to stereo.
1956 Map channels from inputs to output. The argument is a '|'-separated list of
1957 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1958 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1959 can be either the name of the input channel (e.g. FL for front left) or its
1960 index in the specified input stream. @var{out_channel} is the name of the output
1964 The filter will attempt to guess the mappings when they are not specified
1965 explicitly. It does so by first trying to find an unused matching input channel
1966 and if that fails it picks the first unused input channel.
1968 Join 3 inputs (with properly set channel layouts):
1970 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1973 Build a 5.1 output from 6 single-channel streams:
1975 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1976 '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'
1982 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
1984 To enable compilation of this filter you need to configure FFmpeg with
1985 @code{--enable-ladspa}.
1989 Specifies the name of LADSPA plugin library to load. If the environment
1990 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
1991 each one of the directories specified by the colon separated list in
1992 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
1993 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
1994 @file{/usr/lib/ladspa/}.
1997 Specifies the plugin within the library. Some libraries contain only
1998 one plugin, but others contain many of them. If this is not set filter
1999 will list all available plugins within the specified library.
2002 Set the '|' separated list of controls which are zero or more floating point
2003 values that determine the behavior of the loaded plugin (for example delay,
2005 Controls need to be defined using the following syntax:
2006 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
2007 @var{valuei} is the value set on the @var{i}-th control.
2008 Alternatively they can be also defined using the following syntax:
2009 @var{value0}|@var{value1}|@var{value2}|..., where
2010 @var{valuei} is the value set on the @var{i}-th control.
2011 If @option{controls} is set to @code{help}, all available controls and
2012 their valid ranges are printed.
2014 @item sample_rate, s
2015 Specify the sample rate, default to 44100. Only used if plugin have
2019 Set the number of samples per channel per each output frame, default
2020 is 1024. Only used if plugin have zero inputs.
2023 Set the minimum duration of the sourced audio. See
2024 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2025 for the accepted syntax.
2026 Note that the resulting duration may be greater than the specified duration,
2027 as the generated audio is always cut at the end of a complete frame.
2028 If not specified, or the expressed duration is negative, the audio is
2029 supposed to be generated forever.
2030 Only used if plugin have zero inputs.
2034 @subsection Examples
2038 List all available plugins within amp (LADSPA example plugin) library:
2044 List all available controls and their valid ranges for @code{vcf_notch}
2045 plugin from @code{VCF} library:
2047 ladspa=f=vcf:p=vcf_notch:c=help
2051 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
2054 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
2058 Add reverberation to the audio using TAP-plugins
2059 (Tom's Audio Processing plugins):
2061 ladspa=file=tap_reverb:tap_reverb
2065 Generate white noise, with 0.2 amplitude:
2067 ladspa=file=cmt:noise_source_white:c=c0=.2
2071 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
2072 @code{C* Audio Plugin Suite} (CAPS) library:
2074 ladspa=file=caps:Click:c=c1=20'
2078 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
2080 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
2084 Increase volume by 20dB using fast lookahead limiter from Steve Harris
2085 @code{SWH Plugins} collection:
2087 ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2
2091 Attenuate low frequencies using Multiband EQ from Steve Harris
2092 @code{SWH Plugins} collection:
2094 ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0
2098 @subsection Commands
2100 This filter supports the following commands:
2103 Modify the @var{N}-th control value.
2105 If the specified value is not valid, it is ignored and prior one is kept.
2110 Apply a low-pass filter with 3dB point frequency.
2111 The filter can be either single-pole or double-pole (the default).
2112 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2114 The filter accepts the following options:
2118 Set frequency in Hz. Default is 500.
2121 Set number of poles. Default is 2.
2124 Set method to specify band-width of filter.
2137 Specify the band-width of a filter in width_type units.
2138 Applies only to double-pole filter.
2139 The default is 0.707q and gives a Butterworth response.
2145 Mix channels with specific gain levels. The filter accepts the output
2146 channel layout followed by a set of channels definitions.
2148 This filter is also designed to efficiently remap the channels of an audio
2151 The filter accepts parameters of the form:
2152 "@var{l}|@var{outdef}|@var{outdef}|..."
2156 output channel layout or number of channels
2159 output channel specification, of the form:
2160 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
2163 output channel to define, either a channel name (FL, FR, etc.) or a channel
2164 number (c0, c1, etc.)
2167 multiplicative coefficient for the channel, 1 leaving the volume unchanged
2170 input channel to use, see out_name for details; it is not possible to mix
2171 named and numbered input channels
2174 If the `=' in a channel specification is replaced by `<', then the gains for
2175 that specification will be renormalized so that the total is 1, thus
2176 avoiding clipping noise.
2178 @subsection Mixing examples
2180 For example, if you want to down-mix from stereo to mono, but with a bigger
2181 factor for the left channel:
2183 pan=1c|c0=0.9*c0+0.1*c1
2186 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
2187 7-channels surround:
2189 pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
2192 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
2193 that should be preferred (see "-ac" option) unless you have very specific
2196 @subsection Remapping examples
2198 The channel remapping will be effective if, and only if:
2201 @item gain coefficients are zeroes or ones,
2202 @item only one input per channel output,
2205 If all these conditions are satisfied, the filter will notify the user ("Pure
2206 channel mapping detected"), and use an optimized and lossless method to do the
2209 For example, if you have a 5.1 source and want a stereo audio stream by
2210 dropping the extra channels:
2212 pan="stereo| c0=FL | c1=FR"
2215 Given the same source, you can also switch front left and front right channels
2216 and keep the input channel layout:
2218 pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
2221 If the input is a stereo audio stream, you can mute the front left channel (and
2222 still keep the stereo channel layout) with:
2227 Still with a stereo audio stream input, you can copy the right channel in both
2228 front left and right:
2230 pan="stereo| c0=FR | c1=FR"
2235 ReplayGain scanner filter. This filter takes an audio stream as an input and
2236 outputs it unchanged.
2237 At end of filtering it displays @code{track_gain} and @code{track_peak}.
2241 Convert the audio sample format, sample rate and channel layout. It is
2242 not meant to be used directly.
2244 @section sidechaincompress
2246 This filter acts like normal compressor but has the ability to compress
2247 detected signal using second input signal.
2248 It needs two input streams and returns one output stream.
2249 First input stream will be processed depending on second stream signal.
2250 The filtered signal then can be filtered with other filters in later stages of
2251 processing. See @ref{pan} and @ref{amerge} filter.
2253 The filter accepts the following options:
2257 If a signal of second stream raises above this level it will affect the gain
2258 reduction of first stream.
2259 By default is 0.125. Range is between 0.00097563 and 1.
2262 Set a ratio about which the signal is reduced. 1:2 means that if the level
2263 raised 4dB above the threshold, it will be only 2dB above after the reduction.
2264 Default is 2. Range is between 1 and 20.
2267 Amount of milliseconds the signal has to rise above the threshold before gain
2268 reduction starts. Default is 20. Range is between 0.01 and 2000.
2271 Amount of milliseconds the signal has to fall bellow the threshold before
2272 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
2275 Set the amount by how much signal will be amplified after processing.
2276 Default is 2. Range is from 1 and 64.
2279 Curve the sharp knee around the threshold to enter gain reduction more softly.
2280 Default is 2.82843. Range is between 1 and 8.
2283 Choose if the @code{average} level between all channels of side-chain stream
2284 or the louder(@code{maximum}) channel of side-chain stream affects the
2285 reduction. Default is @code{average}.
2288 Should the exact signal be taken in case of @code{peak} or an RMS one in case
2289 of @code{rms}. Default is @code{rms} which is mainly smoother.
2292 @subsection Examples
2296 Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
2297 depending on the signal of 2nd input and later compressed signal to be
2298 merged with 2nd input:
2300 ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
2304 @section silencedetect
2306 Detect silence in an audio stream.
2308 This filter logs a message when it detects that the input audio volume is less
2309 or equal to a noise tolerance value for a duration greater or equal to the
2310 minimum detected noise duration.
2312 The printed times and duration are expressed in seconds.
2314 The filter accepts the following options:
2318 Set silence duration until notification (default is 2 seconds).
2321 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
2322 specified value) or amplitude ratio. Default is -60dB, or 0.001.
2325 @subsection Examples
2329 Detect 5 seconds of silence with -50dB noise tolerance:
2331 silencedetect=n=-50dB:d=5
2335 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
2336 tolerance in @file{silence.mp3}:
2338 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
2342 @section silenceremove
2344 Remove silence from the beginning, middle or end of the audio.
2346 The filter accepts the following options:
2350 This value is used to indicate if audio should be trimmed at beginning of
2351 the audio. A value of zero indicates no silence should be trimmed from the
2352 beginning. When specifying a non-zero value, it trims audio up until it
2353 finds non-silence. Normally, when trimming silence from beginning of audio
2354 the @var{start_periods} will be @code{1} but it can be increased to higher
2355 values to trim all audio up to specific count of non-silence periods.
2356 Default value is @code{0}.
2358 @item start_duration
2359 Specify the amount of time that non-silence must be detected before it stops
2360 trimming audio. By increasing the duration, bursts of noises can be treated
2361 as silence and trimmed off. Default value is @code{0}.
2363 @item start_threshold
2364 This indicates what sample value should be treated as silence. For digital
2365 audio, a value of @code{0} may be fine but for audio recorded from analog,
2366 you may wish to increase the value to account for background noise.
2367 Can be specified in dB (in case "dB" is appended to the specified value)
2368 or amplitude ratio. Default value is @code{0}.
2371 Set the count for trimming silence from the end of audio.
2372 To remove silence from the middle of a file, specify a @var{stop_periods}
2373 that is negative. This value is then treated as a positive value and is
2374 used to indicate the effect should restart processing as specified by
2375 @var{start_periods}, making it suitable for removing periods of silence
2376 in the middle of the audio.
2377 Default value is @code{0}.
2380 Specify a duration of silence that must exist before audio is not copied any
2381 more. By specifying a higher duration, silence that is wanted can be left in
2383 Default value is @code{0}.
2385 @item stop_threshold
2386 This is the same as @option{start_threshold} but for trimming silence from
2388 Can be specified in dB (in case "dB" is appended to the specified value)
2389 or amplitude ratio. Default value is @code{0}.
2392 This indicate that @var{stop_duration} length of audio should be left intact
2393 at the beginning of each period of silence.
2394 For example, if you want to remove long pauses between words but do not want
2395 to remove the pauses completely. Default value is @code{0}.
2399 @subsection Examples
2403 The following example shows how this filter can be used to start a recording
2404 that does not contain the delay at the start which usually occurs between
2405 pressing the record button and the start of the performance:
2407 silenceremove=1:5:0.02
2411 @section stereowiden
2413 This filter enhance the stereo effect by suppressing signal common to both
2414 channels and by delaying the signal of left into right and vice versa,
2415 thereby widening the stereo effect.
2417 The filter accepts the following options:
2421 Time in milliseconds of the delay of left signal into right and vice versa.
2422 Default is 20 milliseconds.
2425 Amount of gain in delayed signal into right and vice versa. Gives a delay
2426 effect of left signal in right output and vice versa which gives widening
2427 effect. Default is 0.3.
2430 Cross feed of left into right with inverted phase. This helps in suppressing
2431 the mono. If the value is 1 it will cancel all the signal common to both
2432 channels. Default is 0.3.
2435 Set level of input signal of original channel. Default is 0.8.
2440 Boost or cut treble (upper) frequencies of the audio using a two-pole
2441 shelving filter with a response similar to that of a standard
2442 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
2444 The filter accepts the following options:
2448 Give the gain at whichever is the lower of ~22 kHz and the
2449 Nyquist frequency. Its useful range is about -20 (for a large cut)
2450 to +20 (for a large boost). Beware of clipping when using a positive gain.
2453 Set the filter's central frequency and so can be used
2454 to extend or reduce the frequency range to be boosted or cut.
2455 The default value is @code{3000} Hz.
2458 Set method to specify band-width of filter.
2471 Determine how steep is the filter's shelf transition.
2476 Adjust the input audio volume.
2478 It accepts the following parameters:
2482 Set audio volume expression.
2484 Output values are clipped to the maximum value.
2486 The output audio volume is given by the relation:
2488 @var{output_volume} = @var{volume} * @var{input_volume}
2491 The default value for @var{volume} is "1.0".
2494 This parameter represents the mathematical precision.
2496 It determines which input sample formats will be allowed, which affects the
2497 precision of the volume scaling.
2501 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
2503 32-bit floating-point; this limits input sample format to FLT. (default)
2505 64-bit floating-point; this limits input sample format to DBL.
2509 Choose the behaviour on encountering ReplayGain side data in input frames.
2513 Remove ReplayGain side data, ignoring its contents (the default).
2516 Ignore ReplayGain side data, but leave it in the frame.
2519 Prefer the track gain, if present.
2522 Prefer the album gain, if present.
2525 @item replaygain_preamp
2526 Pre-amplification gain in dB to apply to the selected replaygain gain.
2528 Default value for @var{replaygain_preamp} is 0.0.
2531 Set when the volume expression is evaluated.
2533 It accepts the following values:
2536 only evaluate expression once during the filter initialization, or
2537 when the @samp{volume} command is sent
2540 evaluate expression for each incoming frame
2543 Default value is @samp{once}.
2546 The volume expression can contain the following parameters.
2550 frame number (starting at zero)
2553 @item nb_consumed_samples
2554 number of samples consumed by the filter
2556 number of samples in the current frame
2558 original frame position in the file
2564 PTS at start of stream
2566 time at start of stream
2572 last set volume value
2575 Note that when @option{eval} is set to @samp{once} only the
2576 @var{sample_rate} and @var{tb} variables are available, all other
2577 variables will evaluate to NAN.
2579 @subsection Commands
2581 This filter supports the following commands:
2584 Modify the volume expression.
2585 The command accepts the same syntax of the corresponding option.
2587 If the specified expression is not valid, it is kept at its current
2589 @item replaygain_noclip
2590 Prevent clipping by limiting the gain applied.
2592 Default value for @var{replaygain_noclip} is 1.
2596 @subsection Examples
2600 Halve the input audio volume:
2604 volume=volume=-6.0206dB
2607 In all the above example the named key for @option{volume} can be
2608 omitted, for example like in:
2614 Increase input audio power by 6 decibels using fixed-point precision:
2616 volume=volume=6dB:precision=fixed
2620 Fade volume after time 10 with an annihilation period of 5 seconds:
2622 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
2626 @section volumedetect
2628 Detect the volume of the input video.
2630 The filter has no parameters. The input is not modified. Statistics about
2631 the volume will be printed in the log when the input stream end is reached.
2633 In particular it will show the mean volume (root mean square), maximum
2634 volume (on a per-sample basis), and the beginning of a histogram of the
2635 registered volume values (from the maximum value to a cumulated 1/1000 of
2638 All volumes are in decibels relative to the maximum PCM value.
2640 @subsection Examples
2642 Here is an excerpt of the output:
2644 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
2645 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
2646 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
2647 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
2648 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
2649 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
2650 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
2651 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
2652 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
2658 The mean square energy is approximately -27 dB, or 10^-2.7.
2660 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
2662 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
2665 In other words, raising the volume by +4 dB does not cause any clipping,
2666 raising it by +5 dB causes clipping for 6 samples, etc.
2668 @c man end AUDIO FILTERS
2670 @chapter Audio Sources
2671 @c man begin AUDIO SOURCES
2673 Below is a description of the currently available audio sources.
2677 Buffer audio frames, and make them available to the filter chain.
2679 This source is mainly intended for a programmatic use, in particular
2680 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
2682 It accepts the following parameters:
2686 The timebase which will be used for timestamps of submitted frames. It must be
2687 either a floating-point number or in @var{numerator}/@var{denominator} form.
2690 The sample rate of the incoming audio buffers.
2693 The sample format of the incoming audio buffers.
2694 Either a sample format name or its corresponding integer representation from
2695 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
2697 @item channel_layout
2698 The channel layout of the incoming audio buffers.
2699 Either a channel layout name from channel_layout_map in
2700 @file{libavutil/channel_layout.c} or its corresponding integer representation
2701 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
2704 The number of channels of the incoming audio buffers.
2705 If both @var{channels} and @var{channel_layout} are specified, then they
2710 @subsection Examples
2713 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
2716 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
2717 Since the sample format with name "s16p" corresponds to the number
2718 6 and the "stereo" channel layout corresponds to the value 0x3, this is
2721 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
2726 Generate an audio signal specified by an expression.
2728 This source accepts in input one or more expressions (one for each
2729 channel), which are evaluated and used to generate a corresponding
2732 This source accepts the following options:
2736 Set the '|'-separated expressions list for each separate channel. In case the
2737 @option{channel_layout} option is not specified, the selected channel layout
2738 depends on the number of provided expressions. Otherwise the last
2739 specified expression is applied to the remaining output channels.
2741 @item channel_layout, c
2742 Set the channel layout. The number of channels in the specified layout
2743 must be equal to the number of specified expressions.
2746 Set the minimum duration of the sourced audio. See
2747 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2748 for the accepted syntax.
2749 Note that the resulting duration may be greater than the specified
2750 duration, as the generated audio is always cut at the end of a
2753 If not specified, or the expressed duration is negative, the audio is
2754 supposed to be generated forever.
2757 Set the number of samples per channel per each output frame,
2760 @item sample_rate, s
2761 Specify the sample rate, default to 44100.
2764 Each expression in @var{exprs} can contain the following constants:
2768 number of the evaluated sample, starting from 0
2771 time of the evaluated sample expressed in seconds, starting from 0
2778 @subsection Examples
2788 Generate a sin signal with frequency of 440 Hz, set sample rate to
2791 aevalsrc="sin(440*2*PI*t):s=8000"
2795 Generate a two channels signal, specify the channel layout (Front
2796 Center + Back Center) explicitly:
2798 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
2802 Generate white noise:
2804 aevalsrc="-2+random(0)"
2808 Generate an amplitude modulated signal:
2810 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
2814 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
2816 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
2823 The null audio source, return unprocessed audio frames. It is mainly useful
2824 as a template and to be employed in analysis / debugging tools, or as
2825 the source for filters which ignore the input data (for example the sox
2828 This source accepts the following options:
2832 @item channel_layout, cl
2834 Specifies the channel layout, and can be either an integer or a string
2835 representing a channel layout. The default value of @var{channel_layout}
2838 Check the channel_layout_map definition in
2839 @file{libavutil/channel_layout.c} for the mapping between strings and
2840 channel layout values.
2842 @item sample_rate, r
2843 Specifies the sample rate, and defaults to 44100.
2846 Set the number of samples per requested frames.
2850 @subsection Examples
2854 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
2856 anullsrc=r=48000:cl=4
2860 Do the same operation with a more obvious syntax:
2862 anullsrc=r=48000:cl=mono
2866 All the parameters need to be explicitly defined.
2870 Synthesize a voice utterance using the libflite library.
2872 To enable compilation of this filter you need to configure FFmpeg with
2873 @code{--enable-libflite}.
2875 Note that the flite library is not thread-safe.
2877 The filter accepts the following options:
2882 If set to 1, list the names of the available voices and exit
2883 immediately. Default value is 0.
2886 Set the maximum number of samples per frame. Default value is 512.
2889 Set the filename containing the text to speak.
2892 Set the text to speak.
2895 Set the voice to use for the speech synthesis. Default value is
2896 @code{kal}. See also the @var{list_voices} option.
2899 @subsection Examples
2903 Read from file @file{speech.txt}, and synthesize the text using the
2904 standard flite voice:
2906 flite=textfile=speech.txt
2910 Read the specified text selecting the @code{slt} voice:
2912 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2916 Input text to ffmpeg:
2918 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2922 Make @file{ffplay} speak the specified text, using @code{flite} and
2923 the @code{lavfi} device:
2925 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
2929 For more information about libflite, check:
2930 @url{http://www.speech.cs.cmu.edu/flite/}
2934 Generate an audio signal made of a sine wave with amplitude 1/8.
2936 The audio signal is bit-exact.
2938 The filter accepts the following options:
2943 Set the carrier frequency. Default is 440 Hz.
2945 @item beep_factor, b
2946 Enable a periodic beep every second with frequency @var{beep_factor} times
2947 the carrier frequency. Default is 0, meaning the beep is disabled.
2949 @item sample_rate, r
2950 Specify the sample rate, default is 44100.
2953 Specify the duration of the generated audio stream.
2955 @item samples_per_frame
2956 Set the number of samples per output frame.
2958 The expression can contain the following constants:
2962 The (sequential) number of the output audio frame, starting from 0.
2965 The PTS (Presentation TimeStamp) of the output audio frame,
2966 expressed in @var{TB} units.
2969 The PTS of the output audio frame, expressed in seconds.
2972 The timebase of the output audio frames.
2975 Default is @code{1024}.
2978 @subsection Examples
2983 Generate a simple 440 Hz sine wave:
2989 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
2993 sine=frequency=220:beep_factor=4:duration=5
2997 Generate a 1 kHz sine wave following @code{1602,1601,1602,1601,1602} NTSC
3000 sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
3004 @c man end AUDIO SOURCES
3006 @chapter Audio Sinks
3007 @c man begin AUDIO SINKS
3009 Below is a description of the currently available audio sinks.
3011 @section abuffersink
3013 Buffer audio frames, and make them available to the end of filter chain.
3015 This sink is mainly intended for programmatic use, in particular
3016 through the interface defined in @file{libavfilter/buffersink.h}
3017 or the options system.
3019 It accepts a pointer to an AVABufferSinkContext structure, which
3020 defines the incoming buffers' formats, to be passed as the opaque
3021 parameter to @code{avfilter_init_filter} for initialization.
3024 Null audio sink; do absolutely nothing with the input audio. It is
3025 mainly useful as a template and for use in analysis / debugging
3028 @c man end AUDIO SINKS
3030 @chapter Video Filters
3031 @c man begin VIDEO FILTERS
3033 When you configure your FFmpeg build, you can disable any of the
3034 existing filters using @code{--disable-filters}.
3035 The configure output will show the video filters included in your
3038 Below is a description of the currently available video filters.
3040 @section alphaextract
3042 Extract the alpha component from the input as a grayscale video. This
3043 is especially useful with the @var{alphamerge} filter.
3047 Add or replace the alpha component of the primary input with the
3048 grayscale value of a second input. This is intended for use with
3049 @var{alphaextract} to allow the transmission or storage of frame
3050 sequences that have alpha in a format that doesn't support an alpha
3053 For example, to reconstruct full frames from a normal YUV-encoded video
3054 and a separate video created with @var{alphaextract}, you might use:
3056 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
3059 Since this filter is designed for reconstruction, it operates on frame
3060 sequences without considering timestamps, and terminates when either
3061 input reaches end of stream. This will cause problems if your encoding
3062 pipeline drops frames. If you're trying to apply an image as an
3063 overlay to a video stream, consider the @var{overlay} filter instead.
3067 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
3068 and libavformat to work. On the other hand, it is limited to ASS (Advanced
3069 Substation Alpha) subtitles files.
3071 This filter accepts the following option in addition to the common options from
3072 the @ref{subtitles} filter:
3076 Set the shaping engine
3078 Available values are:
3081 The default libass shaping engine, which is the best available.
3083 Fast, font-agnostic shaper that can do only substitutions
3085 Slower shaper using OpenType for substitutions and positioning
3088 The default is @code{auto}.
3092 Apply an Adaptive Temporal Averaging Denoiser to the video input.
3094 The filter accepts the following options:
3098 Set threshold A for 1st plane. Default is 0.02.
3099 Valid range is 0 to 0.3.
3102 Set threshold B for 1st plane. Default is 0.04.
3103 Valid range is 0 to 5.
3106 Set threshold A for 2nd plane. Default is 0.02.
3107 Valid range is 0 to 0.3.
3110 Set threshold B for 2nd plane. Default is 0.04.
3111 Valid range is 0 to 5.
3114 Set threshold A for 3rd plane. Default is 0.02.
3115 Valid range is 0 to 0.3.
3118 Set threshold B for 3rd plane. Default is 0.04.
3119 Valid range is 0 to 5.
3121 Threshold A is designed to react on abrupt changes in the input signal and
3122 threshold B is designed to react on continuous changes in the input signal.
3125 Set number of frames filter will use for averaging. Default is 33. Must be odd
3126 number in range [5, 129].
3131 Compute the bounding box for the non-black pixels in the input frame
3134 This filter computes the bounding box containing all the pixels with a
3135 luminance value greater than the minimum allowed value.
3136 The parameters describing the bounding box are printed on the filter
3139 The filter accepts the following option:
3143 Set the minimal luminance value. Default is @code{16}.
3146 @section blackdetect
3148 Detect video intervals that are (almost) completely black. Can be
3149 useful to detect chapter transitions, commercials, or invalid
3150 recordings. Output lines contains the time for the start, end and
3151 duration of the detected black interval expressed in seconds.
3153 In order to display the output lines, you need to set the loglevel at
3154 least to the AV_LOG_INFO value.
3156 The filter accepts the following options:
3159 @item black_min_duration, d
3160 Set the minimum detected black duration expressed in seconds. It must
3161 be a non-negative floating point number.
3163 Default value is 2.0.
3165 @item picture_black_ratio_th, pic_th
3166 Set the threshold for considering a picture "black".
3167 Express the minimum value for the ratio:
3169 @var{nb_black_pixels} / @var{nb_pixels}
3172 for which a picture is considered black.
3173 Default value is 0.98.
3175 @item pixel_black_th, pix_th
3176 Set the threshold for considering a pixel "black".
3178 The threshold expresses the maximum pixel luminance value for which a
3179 pixel is considered "black". The provided value is scaled according to
3180 the following equation:
3182 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
3185 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
3186 the input video format, the range is [0-255] for YUV full-range
3187 formats and [16-235] for YUV non full-range formats.
3189 Default value is 0.10.
3192 The following example sets the maximum pixel threshold to the minimum
3193 value, and detects only black intervals of 2 or more seconds:
3195 blackdetect=d=2:pix_th=0.00
3200 Detect frames that are (almost) completely black. Can be useful to
3201 detect chapter transitions or commercials. Output lines consist of
3202 the frame number of the detected frame, the percentage of blackness,
3203 the position in the file if known or -1 and the timestamp in seconds.
3205 In order to display the output lines, you need to set the loglevel at
3206 least to the AV_LOG_INFO value.
3208 It accepts the following parameters:
3213 The percentage of the pixels that have to be below the threshold; it defaults to
3216 @item threshold, thresh
3217 The threshold below which a pixel value is considered black; it defaults to
3222 @section blend, tblend
3224 Blend two video frames into each other.
3226 The @code{blend} filter takes two input streams and outputs one
3227 stream, the first input is the "top" layer and second input is
3228 "bottom" layer. Output terminates when shortest input terminates.
3230 The @code{tblend} (time blend) filter takes two consecutive frames
3231 from one single stream, and outputs the result obtained by blending
3232 the new frame on top of the old frame.
3234 A description of the accepted options follows.
3242 Set blend mode for specific pixel component or all pixel components in case
3243 of @var{all_mode}. Default value is @code{normal}.
3245 Available values for component modes are:
3282 Set blend opacity for specific pixel component or all pixel components in case
3283 of @var{all_opacity}. Only used in combination with pixel component blend modes.
3290 Set blend expression for specific pixel component or all pixel components in case
3291 of @var{all_expr}. Note that related mode options will be ignored if those are set.
3293 The expressions can use the following variables:
3297 The sequential number of the filtered frame, starting from @code{0}.
3301 the coordinates of the current sample
3305 the width and height of currently filtered plane
3309 Width and height scale depending on the currently filtered plane. It is the
3310 ratio between the corresponding luma plane number of pixels and the current
3311 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3312 @code{0.5,0.5} for chroma planes.
3315 Time of the current frame, expressed in seconds.
3318 Value of pixel component at current location for first video frame (top layer).
3321 Value of pixel component at current location for second video frame (bottom layer).
3325 Force termination when the shortest input terminates. Default is
3326 @code{0}. This option is only defined for the @code{blend} filter.
3329 Continue applying the last bottom frame after the end of the stream. A value of
3330 @code{0} disable the filter after the last frame of the bottom layer is reached.
3331 Default is @code{1}. This option is only defined for the @code{blend} filter.
3334 @subsection Examples
3338 Apply transition from bottom layer to top layer in first 10 seconds:
3340 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
3344 Apply 1x1 checkerboard effect:
3346 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
3350 Apply uncover left effect:
3352 blend=all_expr='if(gte(N*SW+X,W),A,B)'
3356 Apply uncover down effect:
3358 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
3362 Apply uncover up-left effect:
3364 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
3368 Display differences between the current and the previous frame:
3370 tblend=all_mode=difference128
3376 Apply a boxblur algorithm to the input video.
3378 It accepts the following parameters:
3382 @item luma_radius, lr
3383 @item luma_power, lp
3384 @item chroma_radius, cr
3385 @item chroma_power, cp
3386 @item alpha_radius, ar
3387 @item alpha_power, ap
3391 A description of the accepted options follows.
3394 @item luma_radius, lr
3395 @item chroma_radius, cr
3396 @item alpha_radius, ar
3397 Set an expression for the box radius in pixels used for blurring the
3398 corresponding input plane.
3400 The radius value must be a non-negative number, and must not be
3401 greater than the value of the expression @code{min(w,h)/2} for the
3402 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
3405 Default value for @option{luma_radius} is "2". If not specified,
3406 @option{chroma_radius} and @option{alpha_radius} default to the
3407 corresponding value set for @option{luma_radius}.
3409 The expressions can contain the following constants:
3413 The input width and height in pixels.
3417 The input chroma image width and height in pixels.
3421 The horizontal and vertical chroma subsample values. For example, for the
3422 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
3425 @item luma_power, lp
3426 @item chroma_power, cp
3427 @item alpha_power, ap
3428 Specify how many times the boxblur filter is applied to the
3429 corresponding plane.
3431 Default value for @option{luma_power} is 2. If not specified,
3432 @option{chroma_power} and @option{alpha_power} default to the
3433 corresponding value set for @option{luma_power}.
3435 A value of 0 will disable the effect.
3438 @subsection Examples
3442 Apply a boxblur filter with the luma, chroma, and alpha radii
3445 boxblur=luma_radius=2:luma_power=1
3450 Set the luma radius to 2, and alpha and chroma radius to 0:
3452 boxblur=2:1:cr=0:ar=0
3456 Set the luma and chroma radii to a fraction of the video dimension:
3458 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
3464 Visualize information exported by some codecs.
3466 Some codecs can export information through frames using side-data or other
3467 means. For example, some MPEG based codecs export motion vectors through the
3468 @var{export_mvs} flag in the codec @option{flags2} option.
3470 The filter accepts the following option:
3474 Set motion vectors to visualize.
3476 Available flags for @var{mv} are:
3480 forward predicted MVs of P-frames
3482 forward predicted MVs of B-frames
3484 backward predicted MVs of B-frames
3488 @subsection Examples
3492 Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}:
3494 ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
3498 @section colorbalance
3499 Modify intensity of primary colors (red, green and blue) of input frames.
3501 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
3502 regions for the red-cyan, green-magenta or blue-yellow balance.
3504 A positive adjustment value shifts the balance towards the primary color, a negative
3505 value towards the complementary color.
3507 The filter accepts the following options:
3513 Adjust red, green and blue shadows (darkest pixels).
3518 Adjust red, green and blue midtones (medium pixels).
3523 Adjust red, green and blue highlights (brightest pixels).
3525 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3528 @subsection Examples
3532 Add red color cast to shadows:
3539 RGB colorspace color keying.
3541 The filter accepts the following options:
3545 The color which will be replaced with transparency.
3548 Similarity percentage with the key color.
3550 0.01 matches only the exact key color, while 1.0 matches everything.
3555 0.0 makes pixels either fully transparent, or not transparent at all.
3557 Higher values result in semi-transparent pixels, with a higher transparency
3558 the more similar the pixels color is to the key color.
3561 @subsection Examples
3565 Make every green pixel in the input image transparent:
3567 ffmpeg -i input.png -vf colorkey=green out.png
3571 Overlay a greenscreen-video on top of a static background image.
3573 ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv
3577 @section colorlevels
3579 Adjust video input frames using levels.
3581 The filter accepts the following options:
3588 Adjust red, green, blue and alpha input black point.
3589 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3595 Adjust red, green, blue and alpha input white point.
3596 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{1}.
3598 Input levels are used to lighten highlights (bright tones), darken shadows
3599 (dark tones), change the balance of bright and dark tones.
3605 Adjust red, green, blue and alpha output black point.
3606 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{0}.
3612 Adjust red, green, blue and alpha output white point.
3613 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{1}.
3615 Output levels allows manual selection of a constrained output level range.
3618 @subsection Examples
3622 Make video output darker:
3624 colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
3630 colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
3634 Make video output lighter:
3636 colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
3640 Increase brightness:
3642 colorlevels=romin=0.5:gomin=0.5:bomin=0.5
3646 @section colorchannelmixer
3648 Adjust video input frames by re-mixing color channels.
3650 This filter modifies a color channel by adding the values associated to
3651 the other channels of the same pixels. For example if the value to
3652 modify is red, the output value will be:
3654 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
3657 The filter accepts the following options:
3664 Adjust contribution of input red, green, blue and alpha channels for output red channel.
3665 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
3671 Adjust contribution of input red, green, blue and alpha channels for output green channel.
3672 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
3678 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
3679 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
3685 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
3686 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
3688 Allowed ranges for options are @code{[-2.0, 2.0]}.
3691 @subsection Examples
3695 Convert source to grayscale:
3697 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
3700 Simulate sepia tones:
3702 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
3706 @section colormatrix
3708 Convert color matrix.
3710 The filter accepts the following options:
3715 Specify the source and destination color matrix. Both values must be
3718 The accepted values are:
3734 For example to convert from BT.601 to SMPTE-240M, use the command:
3736 colormatrix=bt601:smpte240m
3741 Copy the input source unchanged to the output. This is mainly useful for
3746 Crop the input video to given dimensions.
3748 It accepts the following parameters:
3752 The width of the output video. It defaults to @code{iw}.
3753 This expression is evaluated only once during the filter
3754 configuration, or when the @samp{w} or @samp{out_w} command is sent.
3757 The height of the output video. It defaults to @code{ih}.
3758 This expression is evaluated only once during the filter
3759 configuration, or when the @samp{h} or @samp{out_h} command is sent.
3762 The horizontal position, in the input video, of the left edge of the output
3763 video. It defaults to @code{(in_w-out_w)/2}.
3764 This expression is evaluated per-frame.
3767 The vertical position, in the input video, of the top edge of the output video.
3768 It defaults to @code{(in_h-out_h)/2}.
3769 This expression is evaluated per-frame.
3772 If set to 1 will force the output display aspect ratio
3773 to be the same of the input, by changing the output sample aspect
3774 ratio. It defaults to 0.
3777 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
3778 expressions containing the following constants:
3783 The computed values for @var{x} and @var{y}. They are evaluated for
3788 The input width and height.
3792 These are the same as @var{in_w} and @var{in_h}.
3796 The output (cropped) width and height.
3800 These are the same as @var{out_w} and @var{out_h}.
3803 same as @var{iw} / @var{ih}
3806 input sample aspect ratio
3809 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3813 horizontal and vertical chroma subsample values. For example for the
3814 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3817 The number of the input frame, starting from 0.
3820 the position in the file of the input frame, NAN if unknown
3823 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
3827 The expression for @var{out_w} may depend on the value of @var{out_h},
3828 and the expression for @var{out_h} may depend on @var{out_w}, but they
3829 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
3830 evaluated after @var{out_w} and @var{out_h}.
3832 The @var{x} and @var{y} parameters specify the expressions for the
3833 position of the top-left corner of the output (non-cropped) area. They
3834 are evaluated for each frame. If the evaluated value is not valid, it
3835 is approximated to the nearest valid value.
3837 The expression for @var{x} may depend on @var{y}, and the expression
3838 for @var{y} may depend on @var{x}.
3840 @subsection Examples
3844 Crop area with size 100x100 at position (12,34).
3849 Using named options, the example above becomes:
3851 crop=w=100:h=100:x=12:y=34
3855 Crop the central input area with size 100x100:
3861 Crop the central input area with size 2/3 of the input video:
3863 crop=2/3*in_w:2/3*in_h
3867 Crop the input video central square:
3874 Delimit the rectangle with the top-left corner placed at position
3875 100:100 and the right-bottom corner corresponding to the right-bottom
3876 corner of the input image.
3878 crop=in_w-100:in_h-100:100:100
3882 Crop 10 pixels from the left and right borders, and 20 pixels from
3883 the top and bottom borders
3885 crop=in_w-2*10:in_h-2*20
3889 Keep only the bottom right quarter of the input image:
3891 crop=in_w/2:in_h/2:in_w/2:in_h/2
3895 Crop height for getting Greek harmony:
3897 crop=in_w:1/PHI*in_w
3901 Apply trembling effect:
3903 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)
3907 Apply erratic camera effect depending on timestamp:
3909 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)"
3913 Set x depending on the value of y:
3915 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
3919 @subsection Commands
3921 This filter supports the following commands:
3927 Set width/height of the output video and the horizontal/vertical position
3929 The command accepts the same syntax of the corresponding option.
3931 If the specified expression is not valid, it is kept at its current
3937 Auto-detect the crop size.
3939 It calculates the necessary cropping parameters and prints the
3940 recommended parameters via the logging system. The detected dimensions
3941 correspond to the non-black area of the input video.
3943 It accepts the following parameters:
3948 Set higher black value threshold, which can be optionally specified
3949 from nothing (0) to everything (255 for 8bit based formats). An intensity
3950 value greater to the set value is considered non-black. It defaults to 24.
3951 You can also specify a value between 0.0 and 1.0 which will be scaled depending
3952 on the bitdepth of the pixel format.
3955 The value which the width/height should be divisible by. It defaults to
3956 16. The offset is automatically adjusted to center the video. Use 2 to
3957 get only even dimensions (needed for 4:2:2 video). 16 is best when
3958 encoding to most video codecs.
3960 @item reset_count, reset
3961 Set the counter that determines after how many frames cropdetect will
3962 reset the previously detected largest video area and start over to
3963 detect the current optimal crop area. Default value is 0.
3965 This can be useful when channel logos distort the video area. 0
3966 indicates 'never reset', and returns the largest area encountered during
3973 Apply color adjustments using curves.
3975 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
3976 component (red, green and blue) has its values defined by @var{N} key points
3977 tied from each other using a smooth curve. The x-axis represents the pixel
3978 values from the input frame, and the y-axis the new pixel values to be set for
3981 By default, a component curve is defined by the two points @var{(0;0)} and
3982 @var{(1;1)}. This creates a straight line where each original pixel value is
3983 "adjusted" to its own value, which means no change to the image.
3985 The filter allows you to redefine these two points and add some more. A new
3986 curve (using a natural cubic spline interpolation) will be define to pass
3987 smoothly through all these new coordinates. The new defined points needs to be
3988 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
3989 be in the @var{[0;1]} interval. If the computed curves happened to go outside
3990 the vector spaces, the values will be clipped accordingly.
3992 If there is no key point defined in @code{x=0}, the filter will automatically
3993 insert a @var{(0;0)} point. In the same way, if there is no key point defined
3994 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
3996 The filter accepts the following options:
4000 Select one of the available color presets. This option can be used in addition
4001 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
4002 options takes priority on the preset values.
4003 Available presets are:
4006 @item color_negative
4009 @item increase_contrast
4011 @item linear_contrast
4012 @item medium_contrast
4014 @item strong_contrast
4017 Default is @code{none}.
4019 Set the master key points. These points will define a second pass mapping. It
4020 is sometimes called a "luminance" or "value" mapping. It can be used with
4021 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
4022 post-processing LUT.
4024 Set the key points for the red component.
4026 Set the key points for the green component.
4028 Set the key points for the blue component.
4030 Set the key points for all components (not including master).
4031 Can be used in addition to the other key points component
4032 options. In this case, the unset component(s) will fallback on this
4033 @option{all} setting.
4035 Specify a Photoshop curves file (@code{.acv}) to import the settings from.
4038 To avoid some filtergraph syntax conflicts, each key points list need to be
4039 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
4041 @subsection Examples
4045 Increase slightly the middle level of blue:
4047 curves=blue='0.5/0.58'
4053 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
4055 Here we obtain the following coordinates for each components:
4058 @code{(0;0.11) (0.42;0.51) (1;0.95)}
4060 @code{(0;0) (0.50;0.48) (1;1)}
4062 @code{(0;0.22) (0.49;0.44) (1;0.80)}
4066 The previous example can also be achieved with the associated built-in preset:
4068 curves=preset=vintage
4078 Use a Photoshop preset and redefine the points of the green component:
4080 curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'
4086 Denoise frames using 2D DCT (frequency domain filtering).
4088 This filter is not designed for real time.
4090 The filter accepts the following options:
4094 Set the noise sigma constant.
4096 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
4097 coefficient (absolute value) below this threshold with be dropped.
4099 If you need a more advanced filtering, see @option{expr}.
4101 Default is @code{0}.
4104 Set number overlapping pixels for each block. Since the filter can be slow, you
4105 may want to reduce this value, at the cost of a less effective filter and the
4106 risk of various artefacts.
4108 If the overlapping value doesn't permit processing the whole input width or
4109 height, a warning will be displayed and according borders won't be denoised.
4111 Default value is @var{blocksize}-1, which is the best possible setting.
4114 Set the coefficient factor expression.
4116 For each coefficient of a DCT block, this expression will be evaluated as a
4117 multiplier value for the coefficient.
4119 If this is option is set, the @option{sigma} option will be ignored.
4121 The absolute value of the coefficient can be accessed through the @var{c}
4125 Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the
4126 @var{blocksize}, which is the width and height of the processed blocks.
4128 The default value is @var{3} (8x8) and can be raised to @var{4} for a
4129 @var{blocksize} of 16x16. Note that changing this setting has huge consequences
4130 on the speed processing. Also, a larger block size does not necessarily means a
4134 @subsection Examples
4136 Apply a denoise with a @option{sigma} of @code{4.5}:
4141 The same operation can be achieved using the expression system:
4143 dctdnoiz=e='gte(c, 4.5*3)'
4146 Violent denoise using a block size of @code{16x16}:
4153 Remove banding artifacts from input video.
4154 It works by replacing banded pixels with average value of referenced pixels.
4156 The filter accepts the following options:
4163 Set banding detection threshold for each plane. Default is 0.02.
4164 Valid range is 0.00003 to 0.5.
4165 If difference between current pixel and reference pixel is less than threshold,
4166 it will be considered as banded.
4169 Banding detection range in pixels. Default is 16. If positive, random number
4170 in range 0 to set value will be used. If negative, exact absolute value
4172 The range defines square of four pixels around current pixel.
4175 Set direction in radians from which four pixel will be compared. If positive,
4176 random direction from 0 to set direction will be picked. If negative, exact of
4177 absolute value will be picked. For example direction 0, -PI or -2*PI radians
4178 will pick only pixels on same row and -PI/2 will pick only pixels on same
4182 If enabled, current pixel is compared with average value of all four
4183 surrounding pixels. The default is enabled. If disabled current pixel is
4184 compared with all four surrounding pixels. The pixel is considered banded
4185 if only all four differences with surrounding pixels are less than threshold.
4191 Drop duplicated frames at regular intervals.
4193 The filter accepts the following options:
4197 Set the number of frames from which one will be dropped. Setting this to
4198 @var{N} means one frame in every batch of @var{N} frames will be dropped.
4199 Default is @code{5}.
4202 Set the threshold for duplicate detection. If the difference metric for a frame
4203 is less than or equal to this value, then it is declared as duplicate. Default
4207 Set scene change threshold. Default is @code{15}.
4211 Set the size of the x and y-axis blocks used during metric calculations.
4212 Larger blocks give better noise suppression, but also give worse detection of
4213 small movements. Must be a power of two. Default is @code{32}.
4216 Mark main input as a pre-processed input and activate clean source input
4217 stream. This allows the input to be pre-processed with various filters to help
4218 the metrics calculation while keeping the frame selection lossless. When set to
4219 @code{1}, the first stream is for the pre-processed input, and the second
4220 stream is the clean source from where the kept frames are chosen. Default is
4224 Set whether or not chroma is considered in the metric calculations. Default is
4230 Apply deflate effect to the video.
4232 This filter replaces the pixel by the local(3x3) average by taking into account
4233 only values lower than the pixel.
4235 It accepts the following options:
4242 Allows to limit the maximum change for each plane, default is 65535.
4243 If 0, plane will remain unchanged.
4248 Remove judder produced by partially interlaced telecined content.
4250 Judder can be introduced, for instance, by @ref{pullup} filter. If the original
4251 source was partially telecined content then the output of @code{pullup,dejudder}
4252 will have a variable frame rate. May change the recorded frame rate of the
4253 container. Aside from that change, this filter will not affect constant frame
4256 The option available in this filter is:
4260 Specify the length of the window over which the judder repeats.
4262 Accepts any integer greater than 1. Useful values are:
4266 If the original was telecined from 24 to 30 fps (Film to NTSC).
4269 If the original was telecined from 25 to 30 fps (PAL to NTSC).
4272 If a mixture of the two.
4275 The default is @samp{4}.
4280 Suppress a TV station logo by a simple interpolation of the surrounding
4281 pixels. Just set a rectangle covering the logo and watch it disappear
4282 (and sometimes something even uglier appear - your mileage may vary).
4284 It accepts the following parameters:
4289 Specify the top left corner coordinates of the logo. They must be
4294 Specify the width and height of the logo to clear. They must be
4298 Specify the thickness of the fuzzy edge of the rectangle (added to
4299 @var{w} and @var{h}). The default value is 4.
4302 When set to 1, a green rectangle is drawn on the screen to simplify
4303 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
4304 The default value is 0.
4306 The rectangle is drawn on the outermost pixels which will be (partly)
4307 replaced with interpolated values. The values of the next pixels
4308 immediately outside this rectangle in each direction will be used to
4309 compute the interpolated pixel values inside the rectangle.
4313 @subsection Examples
4317 Set a rectangle covering the area with top left corner coordinates 0,0
4318 and size 100x77, and a band of size 10:
4320 delogo=x=0:y=0:w=100:h=77:band=10
4327 Attempt to fix small changes in horizontal and/or vertical shift. This
4328 filter helps remove camera shake from hand-holding a camera, bumping a
4329 tripod, moving on a vehicle, etc.
4331 The filter accepts the following options:
4339 Specify a rectangular area where to limit the search for motion
4341 If desired the search for motion vectors can be limited to a
4342 rectangular area of the frame defined by its top left corner, width
4343 and height. These parameters have the same meaning as the drawbox
4344 filter which can be used to visualise the position of the bounding
4347 This is useful when simultaneous movement of subjects within the frame
4348 might be confused for camera motion by the motion vector search.
4350 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
4351 then the full frame is used. This allows later options to be set
4352 without specifying the bounding box for the motion vector search.
4354 Default - search the whole frame.
4358 Specify the maximum extent of movement in x and y directions in the
4359 range 0-64 pixels. Default 16.
4362 Specify how to generate pixels to fill blanks at the edge of the
4363 frame. Available values are:
4366 Fill zeroes at blank locations
4368 Original image at blank locations
4370 Extruded edge value at blank locations
4372 Mirrored edge at blank locations
4374 Default value is @samp{mirror}.
4377 Specify the blocksize to use for motion search. Range 4-128 pixels,
4381 Specify the contrast threshold for blocks. Only blocks with more than
4382 the specified contrast (difference between darkest and lightest
4383 pixels) will be considered. Range 1-255, default 125.
4386 Specify the search strategy. Available values are:
4389 Set exhaustive search
4391 Set less exhaustive search.
4393 Default value is @samp{exhaustive}.
4396 If set then a detailed log of the motion search is written to the
4400 If set to 1, specify using OpenCL capabilities, only available if
4401 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
4407 Apply an exact inverse of the telecine operation. It requires a predefined
4408 pattern specified using the pattern option which must be the same as that passed
4409 to the telecine filter.
4411 This filter accepts the following options:
4420 The default value is @code{top}.
4424 A string of numbers representing the pulldown pattern you wish to apply.
4425 The default value is @code{23}.
4428 A number representing position of the first frame with respect to the telecine
4429 pattern. This is to be used if the stream is cut. The default value is @code{0}.
4434 Apply dilation effect to the video.
4436 This filter replaces the pixel by the local(3x3) maximum.
4438 It accepts the following options:
4445 Allows to limit the maximum change for each plane, default is 65535.
4446 If 0, plane will remain unchanged.
4449 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
4452 Flags to local 3x3 coordinates maps like this:
4461 Draw a colored box on the input image.
4463 It accepts the following parameters:
4468 The expressions which specify the top left corner coordinates of the box. It defaults to 0.
4472 The expressions which specify the width and height of the box; if 0 they are interpreted as
4473 the input width and height. It defaults to 0.
4476 Specify the color of the box to write. For the general syntax of this option,
4477 check the "Color" section in the ffmpeg-utils manual. If the special
4478 value @code{invert} is used, the box edge color is the same as the
4479 video with inverted luma.
4482 The expression which sets the thickness of the box edge. Default value is @code{3}.
4484 See below for the list of accepted constants.
4487 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4488 following constants:
4492 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4496 horizontal and vertical chroma subsample values. For example for the
4497 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4501 The input width and height.
4504 The input sample aspect ratio.
4508 The x and y offset coordinates where the box is drawn.
4512 The width and height of the drawn box.
4515 The thickness of the drawn box.
4517 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
4518 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
4522 @subsection Examples
4526 Draw a black box around the edge of the input image:
4532 Draw a box with color red and an opacity of 50%:
4534 drawbox=10:20:200:60:red@@0.5
4537 The previous example can be specified as:
4539 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
4543 Fill the box with pink color:
4545 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
4549 Draw a 2-pixel red 2.40:1 mask:
4551 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
4555 @section drawgraph, adrawgraph
4557 Draw a graph using input video or audio metadata.
4559 It accepts the following parameters:
4563 Set 1st frame metadata key from which metadata values will be used to draw a graph.
4566 Set 1st foreground color expression.
4569 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
4572 Set 2nd foreground color expression.
4575 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
4578 Set 3rd foreground color expression.
4581 Set 4th frame metadata key from which metadata values will be used to draw a graph.
4584 Set 4th foreground color expression.
4587 Set minimal value of metadata value.
4590 Set maximal value of metadata value.
4593 Set graph background color. Default is white.
4598 Available values for mode is:
4605 Default is @code{line}.
4610 Available values for slide is:
4613 Draw new frame when right border is reached.
4616 Replace old columns with new ones.
4619 Scroll from right to left.
4622 Scroll from left to right.
4625 Default is @code{frame}.
4628 Set size of graph video. For the syntax of this option, check the
4629 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
4630 The default value is @code{900x256}.
4632 The foreground color expressions can use the following variables:
4635 Minimal value of metadata value.
4638 Maximal value of metadata value.
4641 Current metadata key value.
4644 The color is defined as 0xAABBGGRR.
4647 Example using metadata from @ref{signalstats} filter:
4649 signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
4652 Example using metadata from @ref{ebur128} filter:
4654 ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
4659 Draw a grid on the input image.
4661 It accepts the following parameters:
4666 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
4670 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
4671 input width and height, respectively, minus @code{thickness}, so image gets
4672 framed. Default to 0.
4675 Specify the color of the grid. For the general syntax of this option,
4676 check the "Color" section in the ffmpeg-utils manual. If the special
4677 value @code{invert} is used, the grid color is the same as the
4678 video with inverted luma.
4681 The expression which sets the thickness of the grid line. Default value is @code{1}.
4683 See below for the list of accepted constants.
4686 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4687 following constants:
4691 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4695 horizontal and vertical chroma subsample values. For example for the
4696 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4700 The input grid cell width and height.
4703 The input sample aspect ratio.
4707 The x and y coordinates of some point of grid intersection (meant to configure offset).
4711 The width and height of the drawn cell.
4714 The thickness of the drawn cell.
4716 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
4717 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
4721 @subsection Examples
4725 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
4727 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
4731 Draw a white 3x3 grid with an opacity of 50%:
4733 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
4740 Draw a text string or text from a specified file on top of a video, using the
4741 libfreetype library.
4743 To enable compilation of this filter, you need to configure FFmpeg with
4744 @code{--enable-libfreetype}.
4745 To enable default font fallback and the @var{font} option you need to
4746 configure FFmpeg with @code{--enable-libfontconfig}.
4747 To enable the @var{text_shaping} option, you need to configure FFmpeg with
4748 @code{--enable-libfribidi}.
4752 It accepts the following parameters:
4757 Used to draw a box around text using the background color.
4758 The value must be either 1 (enable) or 0 (disable).
4759 The default value of @var{box} is 0.
4762 Set the width of the border to be drawn around the box using @var{boxcolor}.
4763 The default value of @var{boxborderw} is 0.
4766 The color to be used for drawing box around text. For the syntax of this
4767 option, check the "Color" section in the ffmpeg-utils manual.
4769 The default value of @var{boxcolor} is "white".
4772 Set the width of the border to be drawn around the text using @var{bordercolor}.
4773 The default value of @var{borderw} is 0.
4776 Set the color to be used for drawing border around text. For the syntax of this
4777 option, check the "Color" section in the ffmpeg-utils manual.
4779 The default value of @var{bordercolor} is "black".
4782 Select how the @var{text} is expanded. Can be either @code{none},
4783 @code{strftime} (deprecated) or
4784 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
4788 If true, check and fix text coords to avoid clipping.
4791 The color to be used for drawing fonts. For the syntax of this option, check
4792 the "Color" section in the ffmpeg-utils manual.
4794 The default value of @var{fontcolor} is "black".
4796 @item fontcolor_expr
4797 String which is expanded the same way as @var{text} to obtain dynamic
4798 @var{fontcolor} value. By default this option has empty value and is not
4799 processed. When this option is set, it overrides @var{fontcolor} option.
4802 The font family to be used for drawing text. By default Sans.
4805 The font file to be used for drawing text. The path must be included.
4806 This parameter is mandatory if the fontconfig support is disabled.
4809 This option does not exist, please see the timeline system
4812 Draw the text applying alpha blending. The value can
4813 be either a number between 0.0 and 1.0
4814 The expression accepts the same variables @var{x, y} do.
4815 The default value is 1.
4816 Please see fontcolor_expr
4819 The font size to be used for drawing text.
4820 The default value of @var{fontsize} is 16.
4823 If set to 1, attempt to shape the text (for example, reverse the order of
4824 right-to-left text and join Arabic characters) before drawing it.
4825 Otherwise, just draw the text exactly as given.
4826 By default 1 (if supported).
4829 The flags to be used for loading the fonts.
4831 The flags map the corresponding flags supported by libfreetype, and are
4832 a combination of the following values:
4839 @item vertical_layout
4840 @item force_autohint
4843 @item ignore_global_advance_width
4845 @item ignore_transform
4851 Default value is "default".
4853 For more information consult the documentation for the FT_LOAD_*
4857 The color to be used for drawing a shadow behind the drawn text. For the
4858 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
4860 The default value of @var{shadowcolor} is "black".
4864 The x and y offsets for the text shadow position with respect to the
4865 position of the text. They can be either positive or negative
4866 values. The default value for both is "0".
4869 The starting frame number for the n/frame_num variable. The default value
4873 The size in number of spaces to use for rendering the tab.
4877 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
4878 format. It can be used with or without text parameter. @var{timecode_rate}
4879 option must be specified.
4881 @item timecode_rate, rate, r
4882 Set the timecode frame rate (timecode only).
4885 The text string to be drawn. The text must be a sequence of UTF-8
4887 This parameter is mandatory if no file is specified with the parameter
4891 A text file containing text to be drawn. The text must be a sequence
4892 of UTF-8 encoded characters.
4894 This parameter is mandatory if no text string is specified with the
4895 parameter @var{text}.
4897 If both @var{text} and @var{textfile} are specified, an error is thrown.
4900 If set to 1, the @var{textfile} will be reloaded before each frame.
4901 Be sure to update it atomically, or it may be read partially, or even fail.
4905 The expressions which specify the offsets where text will be drawn
4906 within the video frame. They are relative to the top/left border of the
4909 The default value of @var{x} and @var{y} is "0".
4911 See below for the list of accepted constants and functions.
4914 The parameters for @var{x} and @var{y} are expressions containing the
4915 following constants and functions:
4919 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
4923 horizontal and vertical chroma subsample values. For example for the
4924 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4927 the height of each text line
4935 @item max_glyph_a, ascent
4936 the maximum distance from the baseline to the highest/upper grid
4937 coordinate used to place a glyph outline point, for all the rendered
4939 It is a positive value, due to the grid's orientation with the Y axis
4942 @item max_glyph_d, descent
4943 the maximum distance from the baseline to the lowest grid coordinate
4944 used to place a glyph outline point, for all the rendered glyphs.
4945 This is a negative value, due to the grid's orientation, with the Y axis
4949 maximum glyph height, that is the maximum height for all the glyphs
4950 contained in the rendered text, it is equivalent to @var{ascent} -
4954 maximum glyph width, that is the maximum width for all the glyphs
4955 contained in the rendered text
4958 the number of input frame, starting from 0
4960 @item rand(min, max)
4961 return a random number included between @var{min} and @var{max}
4964 The input sample aspect ratio.
4967 timestamp expressed in seconds, NAN if the input timestamp is unknown
4970 the height of the rendered text
4973 the width of the rendered text
4977 the x and y offset coordinates where the text is drawn.
4979 These parameters allow the @var{x} and @var{y} expressions to refer
4980 each other, so you can for example specify @code{y=x/dar}.
4983 @anchor{drawtext_expansion}
4984 @subsection Text expansion
4986 If @option{expansion} is set to @code{strftime},
4987 the filter recognizes strftime() sequences in the provided text and
4988 expands them accordingly. Check the documentation of strftime(). This
4989 feature is deprecated.
4991 If @option{expansion} is set to @code{none}, the text is printed verbatim.
4993 If @option{expansion} is set to @code{normal} (which is the default),
4994 the following expansion mechanism is used.
4996 The backslash character @samp{\}, followed by any character, always expands to
4997 the second character.
4999 Sequence of the form @code{%@{...@}} are expanded. The text between the
5000 braces is a function name, possibly followed by arguments separated by ':'.
5001 If the arguments contain special characters or delimiters (':' or '@}'),
5002 they should be escaped.
5004 Note that they probably must also be escaped as the value for the
5005 @option{text} option in the filter argument string and as the filter
5006 argument in the filtergraph description, and possibly also for the shell,
5007 that makes up to four levels of escaping; using a text file avoids these
5010 The following functions are available:
5015 The expression evaluation result.
5017 It must take one argument specifying the expression to be evaluated,
5018 which accepts the same constants and functions as the @var{x} and
5019 @var{y} values. Note that not all constants should be used, for
5020 example the text size is not known when evaluating the expression, so
5021 the constants @var{text_w} and @var{text_h} will have an undefined
5024 @item expr_int_format, eif
5025 Evaluate the expression's value and output as formatted integer.
5027 The first argument is the expression to be evaluated, just as for the @var{expr} function.
5028 The second argument specifies the output format. Allowed values are @samp{x},
5029 @samp{X}, @samp{d} and @samp{u}. They are treated exactly as in the
5030 @code{printf} function.
5031 The third parameter is optional and sets the number of positions taken by the output.
5032 It can be used to add padding with zeros from the left.
5035 The time at which the filter is running, expressed in UTC.
5036 It can accept an argument: a strftime() format string.
5039 The time at which the filter is running, expressed in the local time zone.
5040 It can accept an argument: a strftime() format string.
5043 Frame metadata. It must take one argument specifying metadata key.
5046 The frame number, starting from 0.
5049 A 1 character description of the current picture type.
5052 The timestamp of the current frame.
5053 It can take up to two arguments.
5055 The first argument is the format of the timestamp; it defaults to @code{flt}
5056 for seconds as a decimal number with microsecond accuracy; @code{hms} stands
5057 for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy.
5059 The second argument is an offset added to the timestamp.
5063 @subsection Examples
5067 Draw "Test Text" with font FreeSerif, using the default values for the
5068 optional parameters.
5071 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
5075 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
5076 and y=50 (counting from the top-left corner of the screen), text is
5077 yellow with a red box around it. Both the text and the box have an
5081 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
5082 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
5085 Note that the double quotes are not necessary if spaces are not used
5086 within the parameter list.
5089 Show the text at the center of the video frame:
5091 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
5095 Show a text line sliding from right to left in the last row of the video
5096 frame. The file @file{LONG_LINE} is assumed to contain a single line
5099 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
5103 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
5105 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
5109 Draw a single green letter "g", at the center of the input video.
5110 The glyph baseline is placed at half screen height.
5112 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
5116 Show text for 1 second every 3 seconds:
5118 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
5122 Use fontconfig to set the font. Note that the colons need to be escaped.
5124 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
5128 Print the date of a real-time encoding (see strftime(3)):
5130 drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}'
5134 Show text fading in and out (appearing/disappearing):
5137 DS=1.0 # display start
5138 DE=10.0 # display end
5139 FID=1.5 # fade in duration
5140 FOD=5 # fade out duration
5141 ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%@{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 @}"
5146 For more information about libfreetype, check:
5147 @url{http://www.freetype.org/}.
5149 For more information about fontconfig, check:
5150 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
5152 For more information about libfribidi, check:
5153 @url{http://fribidi.org/}.
5157 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
5159 The filter accepts the following options:
5164 Set low and high threshold values used by the Canny thresholding
5167 The high threshold selects the "strong" edge pixels, which are then
5168 connected through 8-connectivity with the "weak" edge pixels selected
5169 by the low threshold.
5171 @var{low} and @var{high} threshold values must be chosen in the range
5172 [0,1], and @var{low} should be lesser or equal to @var{high}.
5174 Default value for @var{low} is @code{20/255}, and default value for @var{high}
5178 Define the drawing mode.
5182 Draw white/gray wires on black background.
5185 Mix the colors to create a paint/cartoon effect.
5188 Default value is @var{wires}.
5191 @subsection Examples
5195 Standard edge detection with custom values for the hysteresis thresholding:
5197 edgedetect=low=0.1:high=0.4
5201 Painting effect without thresholding:
5203 edgedetect=mode=colormix:high=0
5208 Set brightness, contrast, saturation and approximate gamma adjustment.
5210 The filter accepts the following options:
5214 Set the contrast expression. The value must be a float value in range
5215 @code{-2.0} to @code{2.0}. The default value is "0".
5218 Set the brightness expression. The value must be a float value in
5219 range @code{-1.0} to @code{1.0}. The default value is "0".
5222 Set the saturation expression. The value must be a float in
5223 range @code{0.0} to @code{3.0}. The default value is "1".
5226 Set the gamma expression. The value must be a float in range
5227 @code{0.1} to @code{10.0}. The default value is "1".
5230 Set the gamma expression for red. The value must be a float in
5231 range @code{0.1} to @code{10.0}. The default value is "1".
5234 Set the gamma expression for green. The value must be a float in range
5235 @code{0.1} to @code{10.0}. The default value is "1".
5238 Set the gamma expression for blue. The value must be a float in range
5239 @code{0.1} to @code{10.0}. The default value is "1".
5242 Set the gamma weight expression. It can be used to reduce the effect
5243 of a high gamma value on bright image areas, e.g. keep them from
5244 getting overamplified and just plain white. The value must be a float
5245 in range @code{0.0} to @code{1.0}. A value of @code{0.0} turns the
5246 gamma correction all the way down while @code{1.0} leaves it at its
5247 full strength. Default is "1".
5250 Set when the expressions for brightness, contrast, saturation and
5251 gamma expressions are evaluated.
5253 It accepts the following values:
5256 only evaluate expressions once during the filter initialization or
5257 when a command is processed
5260 evaluate expressions for each incoming frame
5263 Default value is @samp{init}.
5266 The expressions accept the following parameters:
5269 frame count of the input frame starting from 0
5272 byte position of the corresponding packet in the input file, NAN if
5276 frame rate of the input video, NAN if the input frame rate is unknown
5279 timestamp expressed in seconds, NAN if the input timestamp is unknown
5282 @subsection Commands
5283 The filter supports the following commands:
5287 Set the contrast expression.
5290 Set the brightness expression.
5293 Set the saturation expression.
5296 Set the gamma expression.
5299 Set the gamma_r expression.
5302 Set gamma_g expression.
5305 Set gamma_b expression.
5308 Set gamma_weight expression.
5310 The command accepts the same syntax of the corresponding option.
5312 If the specified expression is not valid, it is kept at its current
5319 Apply erosion effect to the video.
5321 This filter replaces the pixel by the local(3x3) minimum.
5323 It accepts the following options:
5330 Allows to limit the maximum change for each plane, default is 65535.
5331 If 0, plane will remain unchanged.
5334 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
5337 Flags to local 3x3 coordinates maps like this:
5344 @section extractplanes
5346 Extract color channel components from input video stream into
5347 separate grayscale video streams.
5349 The filter accepts the following option:
5353 Set plane(s) to extract.
5355 Available values for planes are:
5366 Choosing planes not available in the input will result in an error.
5367 That means you cannot select @code{r}, @code{g}, @code{b} planes
5368 with @code{y}, @code{u}, @code{v} planes at same time.
5371 @subsection Examples
5375 Extract luma, u and v color channel component from input video frame
5376 into 3 grayscale outputs:
5378 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
5384 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
5386 For each input image, the filter will compute the optimal mapping from
5387 the input to the output given the codebook length, that is the number
5388 of distinct output colors.
5390 This filter accepts the following options.
5393 @item codebook_length, l
5394 Set codebook length. The value must be a positive integer, and
5395 represents the number of distinct output colors. Default value is 256.
5398 Set the maximum number of iterations to apply for computing the optimal
5399 mapping. The higher the value the better the result and the higher the
5400 computation time. Default value is 1.
5403 Set a random seed, must be an integer included between 0 and
5404 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
5405 will try to use a good random seed on a best effort basis.
5408 Set pal8 output pixel format. This option does not work with codebook
5409 length greater than 256.
5414 Apply a fade-in/out effect to the input video.
5416 It accepts the following parameters:
5420 The effect type can be either "in" for a fade-in, or "out" for a fade-out
5422 Default is @code{in}.
5424 @item start_frame, s
5425 Specify the number of the frame to start applying the fade
5426 effect at. Default is 0.
5429 The number of frames that the fade effect lasts. At the end of the
5430 fade-in effect, the output video will have the same intensity as the input video.
5431 At the end of the fade-out transition, the output video will be filled with the
5432 selected @option{color}.
5436 If set to 1, fade only alpha channel, if one exists on the input.
5439 @item start_time, st
5440 Specify the timestamp (in seconds) of the frame to start to apply the fade
5441 effect. If both start_frame and start_time are specified, the fade will start at
5442 whichever comes last. Default is 0.
5445 The number of seconds for which the fade effect has to last. At the end of the
5446 fade-in effect the output video will have the same intensity as the input video,
5447 at the end of the fade-out transition the output video will be filled with the
5448 selected @option{color}.
5449 If both duration and nb_frames are specified, duration is used. Default is 0
5450 (nb_frames is used by default).
5453 Specify the color of the fade. Default is "black".
5456 @subsection Examples
5460 Fade in the first 30 frames of video:
5465 The command above is equivalent to:
5471 Fade out the last 45 frames of a 200-frame video:
5474 fade=type=out:start_frame=155:nb_frames=45
5478 Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
5480 fade=in:0:25, fade=out:975:25
5484 Make the first 5 frames yellow, then fade in from frame 5-24:
5486 fade=in:5:20:color=yellow
5490 Fade in alpha over first 25 frames of video:
5492 fade=in:0:25:alpha=1
5496 Make the first 5.5 seconds black, then fade in for 0.5 seconds:
5498 fade=t=in:st=5.5:d=0.5
5504 Apply arbitrary expressions to samples in frequency domain
5508 Adjust the dc value (gain) of the luma plane of the image. The filter
5509 accepts an integer value in range @code{0} to @code{1000}. The default
5510 value is set to @code{0}.
5513 Adjust the dc value (gain) of the 1st chroma plane of the image. The
5514 filter accepts an integer value in range @code{0} to @code{1000}. The
5515 default value is set to @code{0}.
5518 Adjust the dc value (gain) of the 2nd chroma plane of the image. The
5519 filter accepts an integer value in range @code{0} to @code{1000}. The
5520 default value is set to @code{0}.
5523 Set the frequency domain weight expression for the luma plane.
5526 Set the frequency domain weight expression for the 1st chroma plane.
5529 Set the frequency domain weight expression for the 2nd chroma plane.
5531 The filter accepts the following variables:
5534 The coordinates of the current sample.
5538 The width and height of the image.
5541 @subsection Examples
5547 fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
5553 fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
5559 fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
5566 Extract a single field from an interlaced image using stride
5567 arithmetic to avoid wasting CPU time. The output frames are marked as
5570 The filter accepts the following options:
5574 Specify whether to extract the top (if the value is @code{0} or
5575 @code{top}) or the bottom field (if the value is @code{1} or
5581 Field matching filter for inverse telecine. It is meant to reconstruct the
5582 progressive frames from a telecined stream. The filter does not drop duplicated
5583 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
5584 followed by a decimation filter such as @ref{decimate} in the filtergraph.
5586 The separation of the field matching and the decimation is notably motivated by
5587 the possibility of inserting a de-interlacing filter fallback between the two.
5588 If the source has mixed telecined and real interlaced content,
5589 @code{fieldmatch} will not be able to match fields for the interlaced parts.
5590 But these remaining combed frames will be marked as interlaced, and thus can be
5591 de-interlaced by a later filter such as @ref{yadif} before decimation.
5593 In addition to the various configuration options, @code{fieldmatch} can take an
5594 optional second stream, activated through the @option{ppsrc} option. If
5595 enabled, the frames reconstruction will be based on the fields and frames from
5596 this second stream. This allows the first input to be pre-processed in order to
5597 help the various algorithms of the filter, while keeping the output lossless
5598 (assuming the fields are matched properly). Typically, a field-aware denoiser,
5599 or brightness/contrast adjustments can help.
5601 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
5602 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
5603 which @code{fieldmatch} is based on. While the semantic and usage are very
5604 close, some behaviour and options names can differ.
5606 The @ref{decimate} filter currently only works for constant frame rate input.
5607 If your input has mixed telecined (30fps) and progressive content with a lower
5608 framerate like 24fps use the following filterchain to produce the necessary cfr
5609 stream: @code{dejudder,fps=30000/1001,fieldmatch,decimate}.
5611 The filter accepts the following options:
5615 Specify the assumed field order of the input stream. Available values are:
5619 Auto detect parity (use FFmpeg's internal parity value).
5621 Assume bottom field first.
5623 Assume top field first.
5626 Note that it is sometimes recommended not to trust the parity announced by the
5629 Default value is @var{auto}.
5632 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
5633 sense that it won't risk creating jerkiness due to duplicate frames when
5634 possible, but if there are bad edits or blended fields it will end up
5635 outputting combed frames when a good match might actually exist. On the other
5636 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
5637 but will almost always find a good frame if there is one. The other values are
5638 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
5639 jerkiness and creating duplicate frames versus finding good matches in sections
5640 with bad edits, orphaned fields, blended fields, etc.
5642 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
5644 Available values are:
5648 2-way matching (p/c)
5650 2-way matching, and trying 3rd match if still combed (p/c + n)
5652 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
5654 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
5655 still combed (p/c + n + u/b)
5657 3-way matching (p/c/n)
5659 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
5660 detected as combed (p/c/n + u/b)
5663 The parenthesis at the end indicate the matches that would be used for that
5664 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
5667 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
5670 Default value is @var{pc_n}.
5673 Mark the main input stream as a pre-processed input, and enable the secondary
5674 input stream as the clean source to pick the fields from. See the filter
5675 introduction for more details. It is similar to the @option{clip2} feature from
5678 Default value is @code{0} (disabled).
5681 Set the field to match from. It is recommended to set this to the same value as
5682 @option{order} unless you experience matching failures with that setting. In
5683 certain circumstances changing the field that is used to match from can have a
5684 large impact on matching performance. Available values are:
5688 Automatic (same value as @option{order}).
5690 Match from the bottom field.
5692 Match from the top field.
5695 Default value is @var{auto}.
5698 Set whether or not chroma is included during the match comparisons. In most
5699 cases it is recommended to leave this enabled. You should set this to @code{0}
5700 only if your clip has bad chroma problems such as heavy rainbowing or other
5701 artifacts. Setting this to @code{0} could also be used to speed things up at
5702 the cost of some accuracy.
5704 Default value is @code{1}.
5708 These define an exclusion band which excludes the lines between @option{y0} and
5709 @option{y1} from being included in the field matching decision. An exclusion
5710 band can be used to ignore subtitles, a logo, or other things that may
5711 interfere with the matching. @option{y0} sets the starting scan line and
5712 @option{y1} sets the ending line; all lines in between @option{y0} and
5713 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
5714 @option{y0} and @option{y1} to the same value will disable the feature.
5715 @option{y0} and @option{y1} defaults to @code{0}.
5718 Set the scene change detection threshold as a percentage of maximum change on
5719 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
5720 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
5721 @option{scthresh} is @code{[0.0, 100.0]}.
5723 Default value is @code{12.0}.
5726 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
5727 account the combed scores of matches when deciding what match to use as the
5728 final match. Available values are:
5732 No final matching based on combed scores.
5734 Combed scores are only used when a scene change is detected.
5736 Use combed scores all the time.
5739 Default is @var{sc}.
5742 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
5743 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
5744 Available values are:
5748 No forced calculation.
5750 Force p/c/n calculations.
5752 Force p/c/n/u/b calculations.
5755 Default value is @var{none}.
5758 This is the area combing threshold used for combed frame detection. This
5759 essentially controls how "strong" or "visible" combing must be to be detected.
5760 Larger values mean combing must be more visible and smaller values mean combing
5761 can be less visible or strong and still be detected. Valid settings are from
5762 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
5763 be detected as combed). This is basically a pixel difference value. A good
5764 range is @code{[8, 12]}.
5766 Default value is @code{9}.
5769 Sets whether or not chroma is considered in the combed frame decision. Only
5770 disable this if your source has chroma problems (rainbowing, etc.) that are
5771 causing problems for the combed frame detection with chroma enabled. Actually,
5772 using @option{chroma}=@var{0} is usually more reliable, except for the case
5773 where there is chroma only combing in the source.
5775 Default value is @code{0}.
5779 Respectively set the x-axis and y-axis size of the window used during combed
5780 frame detection. This has to do with the size of the area in which
5781 @option{combpel} pixels are required to be detected as combed for a frame to be
5782 declared combed. See the @option{combpel} parameter description for more info.
5783 Possible values are any number that is a power of 2 starting at 4 and going up
5786 Default value is @code{16}.
5789 The number of combed pixels inside any of the @option{blocky} by
5790 @option{blockx} size blocks on the frame for the frame to be detected as
5791 combed. While @option{cthresh} controls how "visible" the combing must be, this
5792 setting controls "how much" combing there must be in any localized area (a
5793 window defined by the @option{blockx} and @option{blocky} settings) on the
5794 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
5795 which point no frames will ever be detected as combed). This setting is known
5796 as @option{MI} in TFM/VFM vocabulary.
5798 Default value is @code{80}.
5801 @anchor{p/c/n/u/b meaning}
5802 @subsection p/c/n/u/b meaning
5804 @subsubsection p/c/n
5806 We assume the following telecined stream:
5809 Top fields: 1 2 2 3 4
5810 Bottom fields: 1 2 3 4 4
5813 The numbers correspond to the progressive frame the fields relate to. Here, the
5814 first two frames are progressive, the 3rd and 4th are combed, and so on.
5816 When @code{fieldmatch} is configured to run a matching from bottom
5817 (@option{field}=@var{bottom}) this is how this input stream get transformed:
5822 B 1 2 3 4 4 <-- matching reference
5831 As a result of the field matching, we can see that some frames get duplicated.
5832 To perform a complete inverse telecine, you need to rely on a decimation filter
5833 after this operation. See for instance the @ref{decimate} filter.
5835 The same operation now matching from top fields (@option{field}=@var{top})
5840 T 1 2 2 3 4 <-- matching reference
5850 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
5851 basically, they refer to the frame and field of the opposite parity:
5854 @item @var{p} matches the field of the opposite parity in the previous frame
5855 @item @var{c} matches the field of the opposite parity in the current frame
5856 @item @var{n} matches the field of the opposite parity in the next frame
5861 The @var{u} and @var{b} matching are a bit special in the sense that they match
5862 from the opposite parity flag. In the following examples, we assume that we are
5863 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
5864 'x' is placed above and below each matched fields.
5866 With bottom matching (@option{field}=@var{bottom}):
5871 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
5872 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
5880 With top matching (@option{field}=@var{top}):
5885 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
5886 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
5894 @subsection Examples
5896 Simple IVTC of a top field first telecined stream:
5898 fieldmatch=order=tff:combmatch=none, decimate
5901 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
5903 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
5908 Transform the field order of the input video.
5910 It accepts the following parameters:
5915 The output field order. Valid values are @var{tff} for top field first or @var{bff}
5916 for bottom field first.
5919 The default value is @samp{tff}.
5921 The transformation is done by shifting the picture content up or down
5922 by one line, and filling the remaining line with appropriate picture content.
5923 This method is consistent with most broadcast field order converters.
5925 If the input video is not flagged as being interlaced, or it is already
5926 flagged as being of the required output field order, then this filter does
5927 not alter the incoming video.
5929 It is very useful when converting to or from PAL DV material,
5930 which is bottom field first.
5934 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
5939 Buffer input images and send them when they are requested.
5941 It is mainly useful when auto-inserted by the libavfilter
5944 It does not take parameters.
5948 Find a rectangular object
5950 It accepts the following options:
5954 Filepath of the object image, needs to be in gray8.
5957 Detection threshold, default is 0.5.
5960 Number of mipmaps, default is 3.
5962 @item xmin, ymin, xmax, ymax
5963 Specifies the rectangle in which to search.
5966 @subsection Examples
5970 Generate a representative palette of a given video using @command{ffmpeg}:
5972 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
5978 Cover a rectangular object
5980 It accepts the following options:
5984 Filepath of the optional cover image, needs to be in yuv420.
5989 It accepts the following values:
5992 cover it by the supplied image
5994 cover it by interpolating the surrounding pixels
5997 Default value is @var{blur}.
6000 @subsection Examples
6004 Generate a representative palette of a given video using @command{ffmpeg}:
6006 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6013 Convert the input video to one of the specified pixel formats.
6014 Libavfilter will try to pick one that is suitable as input to
6017 It accepts the following parameters:
6021 A '|'-separated list of pixel format names, such as
6022 "pix_fmts=yuv420p|monow|rgb24".
6026 @subsection Examples
6030 Convert the input video to the @var{yuv420p} format
6032 format=pix_fmts=yuv420p
6035 Convert the input video to any of the formats in the list
6037 format=pix_fmts=yuv420p|yuv444p|yuv410p
6044 Convert the video to specified constant frame rate by duplicating or dropping
6045 frames as necessary.
6047 It accepts the following parameters:
6051 The desired output frame rate. The default is @code{25}.
6056 Possible values are:
6059 zero round towards 0
6063 round towards -infinity
6065 round towards +infinity
6069 The default is @code{near}.
6072 Assume the first PTS should be the given value, in seconds. This allows for
6073 padding/trimming at the start of stream. By default, no assumption is made
6074 about the first frame's expected PTS, so no padding or trimming is done.
6075 For example, this could be set to 0 to pad the beginning with duplicates of
6076 the first frame if a video stream starts after the audio stream or to trim any
6077 frames with a negative PTS.
6081 Alternatively, the options can be specified as a flat string:
6082 @var{fps}[:@var{round}].
6084 See also the @ref{setpts} filter.
6086 @subsection Examples
6090 A typical usage in order to set the fps to 25:
6096 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
6098 fps=fps=film:round=near
6104 Pack two different video streams into a stereoscopic video, setting proper
6105 metadata on supported codecs. The two views should have the same size and
6106 framerate and processing will stop when the shorter video ends. Please note
6107 that you may conveniently adjust view properties with the @ref{scale} and
6110 It accepts the following parameters:
6114 The desired packing format. Supported values are:
6119 The views are next to each other (default).
6122 The views are on top of each other.
6125 The views are packed by line.
6128 The views are packed by column.
6131 The views are temporally interleaved.
6140 # Convert left and right views into a frame-sequential video
6141 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
6143 # Convert views into a side-by-side video with the same output resolution as the input
6144 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
6149 Change the frame rate by interpolating new video output frames from the source
6152 This filter is not designed to function correctly with interlaced media. If
6153 you wish to change the frame rate of interlaced media then you are required
6154 to deinterlace before this filter and re-interlace after this filter.
6156 A description of the accepted options follows.
6160 Specify the output frames per second. This option can also be specified
6161 as a value alone. The default is @code{50}.
6164 Specify the start of a range where the output frame will be created as a
6165 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6166 the default is @code{15}.
6169 Specify the end of a range where the output frame will be created as a
6170 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6171 the default is @code{240}.
6174 Specify the level at which a scene change is detected as a value between
6175 0 and 100 to indicate a new scene; a low value reflects a low
6176 probability for the current frame to introduce a new scene, while a higher
6177 value means the current frame is more likely to be one.
6178 The default is @code{7}.
6181 Specify flags influencing the filter process.
6183 Available value for @var{flags} is:
6186 @item scene_change_detect, scd
6187 Enable scene change detection using the value of the option @var{scene}.
6188 This flag is enabled by default.
6194 Select one frame every N-th frame.
6196 This filter accepts the following option:
6199 Select frame after every @code{step} frames.
6200 Allowed values are positive integers higher than 0. Default value is @code{1}.
6206 Apply a frei0r effect to the input video.
6208 To enable the compilation of this filter, you need to install the frei0r
6209 header and configure FFmpeg with @code{--enable-frei0r}.
6211 It accepts the following parameters:
6216 The name of the frei0r effect to load. If the environment variable
6217 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
6218 directories specified by the colon-separated list in @env{FREIOR_PATH}.
6219 Otherwise, the standard frei0r paths are searched, in this order:
6220 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
6221 @file{/usr/lib/frei0r-1/}.
6224 A '|'-separated list of parameters to pass to the frei0r effect.
6228 A frei0r effect parameter can be a boolean (its value is either
6229 "y" or "n"), a double, a color (specified as
6230 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
6231 numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
6232 section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where
6233 @var{X} and @var{Y} are floating point numbers) and/or a string.
6235 The number and types of parameters depend on the loaded effect. If an
6236 effect parameter is not specified, the default value is set.
6238 @subsection Examples
6242 Apply the distort0r effect, setting the first two double parameters:
6244 frei0r=filter_name=distort0r:filter_params=0.5|0.01
6248 Apply the colordistance effect, taking a color as the first parameter:
6250 frei0r=colordistance:0.2/0.3/0.4
6251 frei0r=colordistance:violet
6252 frei0r=colordistance:0x112233
6256 Apply the perspective effect, specifying the top left and top right image
6259 frei0r=perspective:0.2/0.2|0.8/0.2
6263 For more information, see
6264 @url{http://frei0r.dyne.org}
6268 Apply fast and simple postprocessing. It is a faster version of @ref{spp}.
6270 It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
6271 processing filter, one of them is performed once per block, not per pixel.
6272 This allows for much higher speed.
6274 The filter accepts the following options:
6278 Set quality. This option defines the number of levels for averaging. It accepts
6279 an integer in the range 4-5. Default value is @code{4}.
6282 Force a constant quantization parameter. It accepts an integer in range 0-63.
6283 If not set, the filter will use the QP from the video stream (if available).
6286 Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
6287 more details but also more artifacts, while higher values make the image smoother
6288 but also blurrier. Default value is @code{0} − PSNR optimal.
6291 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
6292 option may cause flicker since the B-Frames have often larger QP. Default is
6293 @code{0} (not enabled).
6299 The filter accepts the following options:
6303 Set the luminance expression.
6305 Set the chrominance blue expression.
6307 Set the chrominance red expression.
6309 Set the alpha expression.
6311 Set the red expression.
6313 Set the green expression.
6315 Set the blue expression.
6318 The colorspace is selected according to the specified options. If one
6319 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
6320 options is specified, the filter will automatically select a YCbCr
6321 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
6322 @option{blue_expr} options is specified, it will select an RGB
6325 If one of the chrominance expression is not defined, it falls back on the other
6326 one. If no alpha expression is specified it will evaluate to opaque value.
6327 If none of chrominance expressions are specified, they will evaluate
6328 to the luminance expression.
6330 The expressions can use the following variables and functions:
6334 The sequential number of the filtered frame, starting from @code{0}.
6338 The coordinates of the current sample.
6342 The width and height of the image.
6346 Width and height scale depending on the currently filtered plane. It is the
6347 ratio between the corresponding luma plane number of pixels and the current
6348 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
6349 @code{0.5,0.5} for chroma planes.
6352 Time of the current frame, expressed in seconds.
6355 Return the value of the pixel at location (@var{x},@var{y}) of the current
6359 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
6363 Return the value of the pixel at location (@var{x},@var{y}) of the
6364 blue-difference chroma plane. Return 0 if there is no such plane.
6367 Return the value of the pixel at location (@var{x},@var{y}) of the
6368 red-difference chroma plane. Return 0 if there is no such plane.
6373 Return the value of the pixel at location (@var{x},@var{y}) of the
6374 red/green/blue component. Return 0 if there is no such component.
6377 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
6378 plane. Return 0 if there is no such plane.
6381 For functions, if @var{x} and @var{y} are outside the area, the value will be
6382 automatically clipped to the closer edge.
6384 @subsection Examples
6388 Flip the image horizontally:
6394 Generate a bidimensional sine wave, with angle @code{PI/3} and a
6395 wavelength of 100 pixels:
6397 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
6401 Generate a fancy enigmatic moving light:
6403 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
6407 Generate a quick emboss effect:
6409 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
6413 Modify RGB components depending on pixel position:
6415 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
6419 Create a radial gradient that is the same size as the input (also see
6420 the @ref{vignette} filter):
6422 geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
6426 Create a linear gradient to use as a mask for another filter, then
6427 compose with @ref{overlay}. In this example the video will gradually
6428 become more blurry from the top to the bottom of the y-axis as defined
6429 by the linear gradient:
6431 ffmpeg -i input.mp4 -filter_complex "geq=lum=255*(Y/H),format=gray[grad];[0:v]boxblur=4[blur];[blur][grad]alphamerge[alpha];[0:v][alpha]overlay" output.mp4
6437 Fix the banding artifacts that are sometimes introduced into nearly flat
6438 regions by truncation to 8bit color depth.
6439 Interpolate the gradients that should go where the bands are, and
6442 It is designed for playback only. Do not use it prior to
6443 lossy compression, because compression tends to lose the dither and
6444 bring back the bands.
6446 It accepts the following parameters:
6451 The maximum amount by which the filter will change any one pixel. This is also
6452 the threshold for detecting nearly flat regions. Acceptable values range from
6453 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
6457 The neighborhood to fit the gradient to. A larger radius makes for smoother
6458 gradients, but also prevents the filter from modifying the pixels near detailed
6459 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
6460 values will be clipped to the valid range.
6464 Alternatively, the options can be specified as a flat string:
6465 @var{strength}[:@var{radius}]
6467 @subsection Examples
6471 Apply the filter with a @code{3.5} strength and radius of @code{8}:
6477 Specify radius, omitting the strength (which will fall-back to the default
6488 Apply a Hald CLUT to a video stream.
6490 First input is the video stream to process, and second one is the Hald CLUT.
6491 The Hald CLUT input can be a simple picture or a complete video stream.
6493 The filter accepts the following options:
6497 Force termination when the shortest input terminates. Default is @code{0}.
6499 Continue applying the last CLUT after the end of the stream. A value of
6500 @code{0} disable the filter after the last frame of the CLUT is reached.
6501 Default is @code{1}.
6504 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
6505 filters share the same internals).
6507 More information about the Hald CLUT can be found on Eskil Steenberg's website
6508 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
6510 @subsection Workflow examples
6512 @subsubsection Hald CLUT video stream
6514 Generate an identity Hald CLUT stream altered with various effects:
6516 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
6519 Note: make sure you use a lossless codec.
6521 Then use it with @code{haldclut} to apply it on some random stream:
6523 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
6526 The Hald CLUT will be applied to the 10 first seconds (duration of
6527 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
6528 to the remaining frames of the @code{mandelbrot} stream.
6530 @subsubsection Hald CLUT with preview
6532 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
6533 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
6534 biggest possible square starting at the top left of the picture. The remaining
6535 padding pixels (bottom or right) will be ignored. This area can be used to add
6536 a preview of the Hald CLUT.
6538 Typically, the following generated Hald CLUT will be supported by the
6539 @code{haldclut} filter:
6542 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
6543 pad=iw+320 [padded_clut];
6544 smptebars=s=320x256, split [a][b];
6545 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
6546 [main][b] overlay=W-320" -frames:v 1 clut.png
6549 It contains the original and a preview of the effect of the CLUT: SMPTE color
6550 bars are displayed on the right-top, and below the same color bars processed by
6553 Then, the effect of this Hald CLUT can be visualized with:
6555 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
6560 Flip the input video horizontally.
6562 For example, to horizontally flip the input video with @command{ffmpeg}:
6564 ffmpeg -i in.avi -vf "hflip" out.avi
6568 This filter applies a global color histogram equalization on a
6571 It can be used to correct video that has a compressed range of pixel
6572 intensities. The filter redistributes the pixel intensities to
6573 equalize their distribution across the intensity range. It may be
6574 viewed as an "automatically adjusting contrast filter". This filter is
6575 useful only for correcting degraded or poorly captured source
6578 The filter accepts the following options:
6582 Determine the amount of equalization to be applied. As the strength
6583 is reduced, the distribution of pixel intensities more-and-more
6584 approaches that of the input frame. The value must be a float number
6585 in the range [0,1] and defaults to 0.200.
6588 Set the maximum intensity that can generated and scale the output
6589 values appropriately. The strength should be set as desired and then
6590 the intensity can be limited if needed to avoid washing-out. The value
6591 must be a float number in the range [0,1] and defaults to 0.210.
6594 Set the antibanding level. If enabled the filter will randomly vary
6595 the luminance of output pixels by a small amount to avoid banding of
6596 the histogram. Possible values are @code{none}, @code{weak} or
6597 @code{strong}. It defaults to @code{none}.
6602 Compute and draw a color distribution histogram for the input video.
6604 The computed histogram is a representation of the color component
6605 distribution in an image.
6607 The filter accepts the following options:
6613 It accepts the following values:
6616 Standard histogram that displays the color components distribution in an
6617 image. Displays color graph for each color component. Shows distribution of
6618 the Y, U, V, A or R, G, B components, depending on input format, in the
6619 current frame. Below each graph a color component scale meter is shown.
6622 Displays chroma values (U/V color placement) in a two dimensional
6623 graph (which is called a vectorscope). The brighter a pixel in the
6624 vectorscope, the more pixels of the input frame correspond to that pixel
6625 (i.e., more pixels have this chroma value). The V component is displayed on
6626 the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost
6627 side being V = 255. The U component is displayed on the vertical (Y) axis,
6628 with the top representing U = 0 and the bottom representing U = 255.
6630 The position of a white pixel in the graph corresponds to the chroma value of
6631 a pixel of the input clip. The graph can therefore be used to read the hue
6632 (color flavor) and the saturation (the dominance of the hue in the color). As
6633 the hue of a color changes, it moves around the square. At the center of the
6634 square the saturation is zero, which means that the corresponding pixel has no
6635 color. If the amount of a specific color is increased (while leaving the other
6636 colors unchanged) the saturation increases, and the indicator moves towards
6637 the edge of the square.
6640 Chroma values in vectorscope, similar as @code{color} but actual chroma values
6644 Per row/column color component graph. In row mode, the graph on the left side
6645 represents color component value 0 and the right side represents value = 255.
6646 In column mode, the top side represents color component value = 0 and bottom
6647 side represents value = 255.
6649 Default value is @code{levels}.
6652 Set height of level in @code{levels}. Default value is @code{200}.
6653 Allowed range is [50, 2048].
6656 Set height of color scale in @code{levels}. Default value is @code{12}.
6657 Allowed range is [0, 40].
6660 Set step for @code{waveform} mode. Smaller values are useful to find out how
6661 many values of the same luminance are distributed across input rows/columns.
6662 Default value is @code{10}. Allowed range is [1, 255].
6665 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
6666 Default is @code{row}.
6668 @item waveform_mirror
6669 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
6670 means mirrored. In mirrored mode, higher values will be represented on the left
6671 side for @code{row} mode and at the top for @code{column} mode. Default is
6672 @code{0} (unmirrored).
6675 Set display mode for @code{waveform} and @code{levels}.
6676 It accepts the following values:
6679 Display separate graph for the color components side by side in
6680 @code{row} waveform mode or one below the other in @code{column} waveform mode
6681 for @code{waveform} histogram mode. For @code{levels} histogram mode,
6682 per color component graphs are placed below each other.
6684 Using this display mode in @code{waveform} histogram mode makes it easy to
6685 spot color casts in the highlights and shadows of an image, by comparing the
6686 contours of the top and the bottom graphs of each waveform. Since whites,
6687 grays, and blacks are characterized by exactly equal amounts of red, green,
6688 and blue, neutral areas of the picture should display three waveforms of
6689 roughly equal width/height. If not, the correction is easy to perform by
6690 making level adjustments the three waveforms.
6693 Presents information identical to that in the @code{parade}, except
6694 that the graphs representing color components are superimposed directly
6697 This display mode in @code{waveform} histogram mode makes it easier to spot
6698 relative differences or similarities in overlapping areas of the color
6699 components that are supposed to be identical, such as neutral whites, grays,
6702 Default is @code{parade}.
6705 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
6706 Default is @code{linear}.
6709 Set what color components to display for mode @code{levels}.
6710 Default is @code{7}.
6713 @subsection Examples
6718 Calculate and draw histogram:
6720 ffplay -i input -vf histogram
6728 This is a high precision/quality 3d denoise filter. It aims to reduce
6729 image noise, producing smooth images and making still images really
6730 still. It should enhance compressibility.
6732 It accepts the following optional parameters:
6736 A non-negative floating point number which specifies spatial luma strength.
6739 @item chroma_spatial
6740 A non-negative floating point number which specifies spatial chroma strength.
6741 It defaults to 3.0*@var{luma_spatial}/4.0.
6744 A floating point number which specifies luma temporal strength. It defaults to
6745 6.0*@var{luma_spatial}/4.0.
6748 A floating point number which specifies chroma temporal strength. It defaults to
6749 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
6754 Apply a high-quality magnification filter designed for pixel art. This filter
6755 was originally created by Maxim Stepin.
6757 It accepts the following option:
6761 Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
6762 @code{hq3x} and @code{4} for @code{hq4x}.
6763 Default is @code{3}.
6767 Stack input videos horizontally.
6769 All streams must be of same pixel format and of same height.
6771 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
6772 to create same output.
6774 The filter accept the following option:
6778 Set number of input streams. Default is 2.
6783 Modify the hue and/or the saturation of the input.
6785 It accepts the following parameters:
6789 Specify the hue angle as a number of degrees. It accepts an expression,
6790 and defaults to "0".
6793 Specify the saturation in the [-10,10] range. It accepts an expression and
6797 Specify the hue angle as a number of radians. It accepts an
6798 expression, and defaults to "0".
6801 Specify the brightness in the [-10,10] range. It accepts an expression and
6805 @option{h} and @option{H} are mutually exclusive, and can't be
6806 specified at the same time.
6808 The @option{b}, @option{h}, @option{H} and @option{s} option values are
6809 expressions containing the following constants:
6813 frame count of the input frame starting from 0
6816 presentation timestamp of the input frame expressed in time base units
6819 frame rate of the input video, NAN if the input frame rate is unknown
6822 timestamp expressed in seconds, NAN if the input timestamp is unknown
6825 time base of the input video
6828 @subsection Examples
6832 Set the hue to 90 degrees and the saturation to 1.0:
6838 Same command but expressing the hue in radians:
6844 Rotate hue and make the saturation swing between 0
6845 and 2 over a period of 1 second:
6847 hue="H=2*PI*t: s=sin(2*PI*t)+1"
6851 Apply a 3 seconds saturation fade-in effect starting at 0:
6856 The general fade-in expression can be written as:
6858 hue="s=min(0\, max((t-START)/DURATION\, 1))"
6862 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
6864 hue="s=max(0\, min(1\, (8-t)/3))"
6867 The general fade-out expression can be written as:
6869 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
6874 @subsection Commands
6876 This filter supports the following commands:
6882 Modify the hue and/or the saturation and/or brightness of the input video.
6883 The command accepts the same syntax of the corresponding option.
6885 If the specified expression is not valid, it is kept at its current
6891 Detect video interlacing type.
6893 This filter tries to detect if the input frames as interlaced, progressive,
6894 top or bottom field first. It will also try and detect fields that are
6895 repeated between adjacent frames (a sign of telecine).
6897 Single frame detection considers only immediately adjacent frames when classifying each frame.
6898 Multiple frame detection incorporates the classification history of previous frames.
6900 The filter will log these metadata values:
6903 @item single.current_frame
6904 Detected type of current frame using single-frame detection. One of:
6905 ``tff'' (top field first), ``bff'' (bottom field first),
6906 ``progressive'', or ``undetermined''
6909 Cumulative number of frames detected as top field first using single-frame detection.
6912 Cumulative number of frames detected as top field first using multiple-frame detection.
6915 Cumulative number of frames detected as bottom field first using single-frame detection.
6917 @item multiple.current_frame
6918 Detected type of current frame using multiple-frame detection. One of:
6919 ``tff'' (top field first), ``bff'' (bottom field first),
6920 ``progressive'', or ``undetermined''
6923 Cumulative number of frames detected as bottom field first using multiple-frame detection.
6925 @item single.progressive
6926 Cumulative number of frames detected as progressive using single-frame detection.
6928 @item multiple.progressive
6929 Cumulative number of frames detected as progressive using multiple-frame detection.
6931 @item single.undetermined
6932 Cumulative number of frames that could not be classified using single-frame detection.
6934 @item multiple.undetermined
6935 Cumulative number of frames that could not be classified using multiple-frame detection.
6937 @item repeated.current_frame
6938 Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''.
6940 @item repeated.neither
6941 Cumulative number of frames with no repeated field.
6944 Cumulative number of frames with the top field repeated from the previous frame's top field.
6946 @item repeated.bottom
6947 Cumulative number of frames with the bottom field repeated from the previous frame's bottom field.
6950 The filter accepts the following options:
6954 Set interlacing threshold.
6956 Set progressive threshold.
6958 Threshold for repeated field detection.
6960 Number of frames after which a given frame's contribution to the
6961 statistics is halved (i.e., it contributes only 0.5 to it's
6962 classification). The default of 0 means that all frames seen are given
6963 full weight of 1.0 forever.
6964 @item analyze_interlaced_flag
6965 When this is not 0 then idet will use the specified number of frames to determine
6966 if the interlaced flag is accurate, it will not count undetermined frames.
6967 If the flag is found to be accurate it will be used without any further
6968 computations, if it is found to be inaccurate it will be cleared without any
6969 further computations. This allows inserting the idet filter as a low computational
6970 method to clean up the interlaced flag
6975 Deinterleave or interleave fields.
6977 This filter allows one to process interlaced images fields without
6978 deinterlacing them. Deinterleaving splits the input frame into 2
6979 fields (so called half pictures). Odd lines are moved to the top
6980 half of the output image, even lines to the bottom half.
6981 You can process (filter) them independently and then re-interleave them.
6983 The filter accepts the following options:
6987 @item chroma_mode, c
6989 Available values for @var{luma_mode}, @var{chroma_mode} and
6990 @var{alpha_mode} are:
6996 @item deinterleave, d
6997 Deinterleave fields, placing one above the other.
7000 Interleave fields. Reverse the effect of deinterleaving.
7002 Default value is @code{none}.
7005 @item chroma_swap, cs
7006 @item alpha_swap, as
7007 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
7012 Apply inflate effect to the video.
7014 This filter replaces the pixel by the local(3x3) average by taking into account
7015 only values higher than the pixel.
7017 It accepts the following options:
7024 Allows to limit the maximum change for each plane, default is 65535.
7025 If 0, plane will remain unchanged.
7030 Simple interlacing filter from progressive contents. This interleaves upper (or
7031 lower) lines from odd frames with lower (or upper) lines from even frames,
7032 halving the frame rate and preserving image height.
7035 Original Original New Frame
7036 Frame 'j' Frame 'j+1' (tff)
7037 ========== =========== ==================
7038 Line 0 --------------------> Frame 'j' Line 0
7039 Line 1 Line 1 ----> Frame 'j+1' Line 1
7040 Line 2 ---------------------> Frame 'j' Line 2
7041 Line 3 Line 3 ----> Frame 'j+1' Line 3
7043 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
7046 It accepts the following optional parameters:
7050 This determines whether the interlaced frame is taken from the even
7051 (tff - default) or odd (bff) lines of the progressive frame.
7054 Enable (default) or disable the vertical lowpass filter to avoid twitter
7055 interlacing and reduce moire patterns.
7060 Deinterlace input video by applying Donald Graft's adaptive kernel
7061 deinterling. Work on interlaced parts of a video to produce
7064 The description of the accepted parameters follows.
7068 Set the threshold which affects the filter's tolerance when
7069 determining if a pixel line must be processed. It must be an integer
7070 in the range [0,255] and defaults to 10. A value of 0 will result in
7071 applying the process on every pixels.
7074 Paint pixels exceeding the threshold value to white if set to 1.
7078 Set the fields order. Swap fields if set to 1, leave fields alone if
7082 Enable additional sharpening if set to 1. Default is 0.
7085 Enable twoway sharpening if set to 1. Default is 0.
7088 @subsection Examples
7092 Apply default values:
7094 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
7098 Enable additional sharpening:
7104 Paint processed pixels in white:
7110 @section lenscorrection
7112 Correct radial lens distortion
7114 This filter can be used to correct for radial distortion as can result from the use
7115 of wide angle lenses, and thereby re-rectify the image. To find the right parameters
7116 one can use tools available for example as part of opencv or simply trial-and-error.
7117 To use opencv use the calibration sample (under samples/cpp) from the opencv sources
7118 and extract the k1 and k2 coefficients from the resulting matrix.
7120 Note that effectively the same filter is available in the open-source tools Krita and
7121 Digikam from the KDE project.
7123 In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
7124 this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
7125 brightness distribution, so you may want to use both filters together in certain
7126 cases, though you will have to take care of ordering, i.e. whether vignetting should
7127 be applied before or after lens correction.
7131 The filter accepts the following options:
7135 Relative x-coordinate of the focal point of the image, and thereby the center of the
7136 distortion. This value has a range [0,1] and is expressed as fractions of the image
7139 Relative y-coordinate of the focal point of the image, and thereby the center of the
7140 distortion. This value has a range [0,1] and is expressed as fractions of the image
7143 Coefficient of the quadratic correction term. 0.5 means no correction.
7145 Coefficient of the double quadratic correction term. 0.5 means no correction.
7148 The formula that generates the correction is:
7150 @var{r_src} = @var{r_tgt} * (1 + @var{k1} * (@var{r_tgt} / @var{r_0})^2 + @var{k2} * (@var{r_tgt} / @var{r_0})^4)
7152 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
7153 distances from the focal point in the source and target images, respectively.
7158 Apply a 3D LUT to an input video.
7160 The filter accepts the following options:
7164 Set the 3D LUT file name.
7166 Currently supported formats:
7178 Select interpolation mode.
7180 Available values are:
7184 Use values from the nearest defined point.
7186 Interpolate values using the 8 points defining a cube.
7188 Interpolate values using a tetrahedron.
7192 @section lut, lutrgb, lutyuv
7194 Compute a look-up table for binding each pixel component input value
7195 to an output value, and apply it to the input video.
7197 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
7198 to an RGB input video.
7200 These filters accept the following parameters:
7203 set first pixel component expression
7205 set second pixel component expression
7207 set third pixel component expression
7209 set fourth pixel component expression, corresponds to the alpha component
7212 set red component expression
7214 set green component expression
7216 set blue component expression
7218 alpha component expression
7221 set Y/luminance component expression
7223 set U/Cb component expression
7225 set V/Cr component expression
7228 Each of them specifies the expression to use for computing the lookup table for
7229 the corresponding pixel component values.
7231 The exact component associated to each of the @var{c*} options depends on the
7234 The @var{lut} filter requires either YUV or RGB pixel formats in input,
7235 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
7237 The expressions can contain the following constants and functions:
7242 The input width and height.
7245 The input value for the pixel component.
7248 The input value, clipped to the @var{minval}-@var{maxval} range.
7251 The maximum value for the pixel component.
7254 The minimum value for the pixel component.
7257 The negated value for the pixel component value, clipped to the
7258 @var{minval}-@var{maxval} range; it corresponds to the expression
7259 "maxval-clipval+minval".
7262 The computed value in @var{val}, clipped to the
7263 @var{minval}-@var{maxval} range.
7265 @item gammaval(gamma)
7266 The computed gamma correction value of the pixel component value,
7267 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
7269 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
7273 All expressions default to "val".
7275 @subsection Examples
7281 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
7282 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
7285 The above is the same as:
7287 lutrgb="r=negval:g=negval:b=negval"
7288 lutyuv="y=negval:u=negval:v=negval"
7298 Remove chroma components, turning the video into a graytone image:
7300 lutyuv="u=128:v=128"
7304 Apply a luma burning effect:
7310 Remove green and blue components:
7316 Set a constant alpha channel value on input:
7318 format=rgba,lutrgb=a="maxval-minval/2"
7322 Correct luminance gamma by a factor of 0.5:
7324 lutyuv=y=gammaval(0.5)
7328 Discard least significant bits of luma:
7330 lutyuv=y='bitand(val, 128+64+32)'
7334 @section mergeplanes
7336 Merge color channel components from several video streams.
7338 The filter accepts up to 4 input streams, and merge selected input
7339 planes to the output video.
7341 This filter accepts the following options:
7344 Set input to output plane mapping. Default is @code{0}.
7346 The mappings is specified as a bitmap. It should be specified as a
7347 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
7348 mapping for the first plane of the output stream. 'A' sets the number of
7349 the input stream to use (from 0 to 3), and 'a' the plane number of the
7350 corresponding input to use (from 0 to 3). The rest of the mappings is
7351 similar, 'Bb' describes the mapping for the output stream second
7352 plane, 'Cc' describes the mapping for the output stream third plane and
7353 'Dd' describes the mapping for the output stream fourth plane.
7356 Set output pixel format. Default is @code{yuva444p}.
7359 @subsection Examples
7363 Merge three gray video streams of same width and height into single video stream:
7365 [a0][a1][a2]mergeplanes=0x001020:yuv444p
7369 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
7371 [a0][a1]mergeplanes=0x00010210:yuva444p
7375 Swap Y and A plane in yuva444p stream:
7377 format=yuva444p,mergeplanes=0x03010200:yuva444p
7381 Swap U and V plane in yuv420p stream:
7383 format=yuv420p,mergeplanes=0x000201:yuv420p
7387 Cast a rgb24 clip to yuv444p:
7389 format=rgb24,mergeplanes=0x000102:yuv444p
7395 Apply motion-compensation deinterlacing.
7397 It needs one field per frame as input and must thus be used together
7398 with yadif=1/3 or equivalent.
7400 This filter accepts the following options:
7403 Set the deinterlacing mode.
7405 It accepts one of the following values:
7410 use iterative motion estimation
7412 like @samp{slow}, but use multiple reference frames.
7414 Default value is @samp{fast}.
7417 Set the picture field parity assumed for the input video. It must be
7418 one of the following values:
7422 assume top field first
7424 assume bottom field first
7427 Default value is @samp{bff}.
7430 Set per-block quantization parameter (QP) used by the internal
7433 Higher values should result in a smoother motion vector field but less
7434 optimal individual vectors. Default value is 1.
7439 Drop frames that do not differ greatly from the previous frame in
7440 order to reduce frame rate.
7442 The main use of this filter is for very-low-bitrate encoding
7443 (e.g. streaming over dialup modem), but it could in theory be used for
7444 fixing movies that were inverse-telecined incorrectly.
7446 A description of the accepted options follows.
7450 Set the maximum number of consecutive frames which can be dropped (if
7451 positive), or the minimum interval between dropped frames (if
7452 negative). If the value is 0, the frame is dropped unregarding the
7453 number of previous sequentially dropped frames.
7460 Set the dropping threshold values.
7462 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
7463 represent actual pixel value differences, so a threshold of 64
7464 corresponds to 1 unit of difference for each pixel, or the same spread
7465 out differently over the block.
7467 A frame is a candidate for dropping if no 8x8 blocks differ by more
7468 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
7469 meaning the whole image) differ by more than a threshold of @option{lo}.
7471 Default value for @option{hi} is 64*12, default value for @option{lo} is
7472 64*5, and default value for @option{frac} is 0.33.
7480 It accepts an integer in input; if non-zero it negates the
7481 alpha component (if available). The default value in input is 0.
7485 Force libavfilter not to use any of the specified pixel formats for the
7486 input to the next filter.
7488 It accepts the following parameters:
7492 A '|'-separated list of pixel format names, such as
7493 apix_fmts=yuv420p|monow|rgb24".
7497 @subsection Examples
7501 Force libavfilter to use a format different from @var{yuv420p} for the
7502 input to the vflip filter:
7504 noformat=pix_fmts=yuv420p,vflip
7508 Convert the input video to any of the formats not contained in the list:
7510 noformat=yuv420p|yuv444p|yuv410p
7516 Add noise on video input frame.
7518 The filter accepts the following options:
7526 Set noise seed for specific pixel component or all pixel components in case
7527 of @var{all_seed}. Default value is @code{123457}.
7529 @item all_strength, alls
7530 @item c0_strength, c0s
7531 @item c1_strength, c1s
7532 @item c2_strength, c2s
7533 @item c3_strength, c3s
7534 Set noise strength for specific pixel component or all pixel components in case
7535 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
7537 @item all_flags, allf
7542 Set pixel component flags or set flags for all components if @var{all_flags}.
7543 Available values for component flags are:
7546 averaged temporal noise (smoother)
7548 mix random noise with a (semi)regular pattern
7550 temporal noise (noise pattern changes between frames)
7552 uniform noise (gaussian otherwise)
7556 @subsection Examples
7558 Add temporal and uniform noise to input video:
7560 noise=alls=20:allf=t+u
7565 Pass the video source unchanged to the output.
7568 Optical Character Recognition
7570 This filter uses Tesseract for optical character recognition.
7572 It accepts the following options:
7576 Set datapath to tesseract data. Default is to use whatever was
7577 set at installation.
7580 Set language, default is "eng".
7583 Set character whitelist.
7586 Set character blacklist.
7589 The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
7593 Apply a video transform using libopencv.
7595 To enable this filter, install the libopencv library and headers and
7596 configure FFmpeg with @code{--enable-libopencv}.
7598 It accepts the following parameters:
7603 The name of the libopencv filter to apply.
7606 The parameters to pass to the libopencv filter. If not specified, the default
7611 Refer to the official libopencv documentation for more precise
7613 @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html}
7615 Several libopencv filters are supported; see the following subsections.
7620 Dilate an image by using a specific structuring element.
7621 It corresponds to the libopencv function @code{cvDilate}.
7623 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
7625 @var{struct_el} represents a structuring element, and has the syntax:
7626 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
7628 @var{cols} and @var{rows} represent the number of columns and rows of
7629 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
7630 point, and @var{shape} the shape for the structuring element. @var{shape}
7631 must be "rect", "cross", "ellipse", or "custom".
7633 If the value for @var{shape} is "custom", it must be followed by a
7634 string of the form "=@var{filename}". The file with name
7635 @var{filename} is assumed to represent a binary image, with each
7636 printable character corresponding to a bright pixel. When a custom
7637 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
7638 or columns and rows of the read file are assumed instead.
7640 The default value for @var{struct_el} is "3x3+0x0/rect".
7642 @var{nb_iterations} specifies the number of times the transform is
7643 applied to the image, and defaults to 1.
7647 # Use the default values
7650 # Dilate using a structuring element with a 5x5 cross, iterating two times
7651 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
7653 # Read the shape from the file diamond.shape, iterating two times.
7654 # The file diamond.shape may contain a pattern of characters like this
7660 # The specified columns and rows are ignored
7661 # but the anchor point coordinates are not
7662 ocv=dilate:0x0+2x2/custom=diamond.shape|2
7667 Erode an image by using a specific structuring element.
7668 It corresponds to the libopencv function @code{cvErode}.
7670 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
7671 with the same syntax and semantics as the @ref{dilate} filter.
7675 Smooth the input video.
7677 The filter takes the following parameters:
7678 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
7680 @var{type} is the type of smooth filter to apply, and must be one of
7681 the following values: "blur", "blur_no_scale", "median", "gaussian",
7682 or "bilateral". The default value is "gaussian".
7684 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
7685 depend on the smooth type. @var{param1} and
7686 @var{param2} accept integer positive values or 0. @var{param3} and
7687 @var{param4} accept floating point values.
7689 The default value for @var{param1} is 3. The default value for the
7690 other parameters is 0.
7692 These parameters correspond to the parameters assigned to the
7693 libopencv function @code{cvSmooth}.
7698 Overlay one video on top of another.
7700 It takes two inputs and has one output. The first input is the "main"
7701 video on which the second input is overlaid.
7703 It accepts the following parameters:
7705 A description of the accepted options follows.
7710 Set the expression for the x and y coordinates of the overlaid video
7711 on the main video. Default value is "0" for both expressions. In case
7712 the expression is invalid, it is set to a huge value (meaning that the
7713 overlay will not be displayed within the output visible area).
7716 The action to take when EOF is encountered on the secondary input; it accepts
7717 one of the following values:
7721 Repeat the last frame (the default).
7725 Pass the main input through.
7729 Set when the expressions for @option{x}, and @option{y} are evaluated.
7731 It accepts the following values:
7734 only evaluate expressions once during the filter initialization or
7735 when a command is processed
7738 evaluate expressions for each incoming frame
7741 Default value is @samp{frame}.
7744 If set to 1, force the output to terminate when the shortest input
7745 terminates. Default value is 0.
7748 Set the format for the output video.
7750 It accepts the following values:
7765 Default value is @samp{yuv420}.
7767 @item rgb @emph{(deprecated)}
7768 If set to 1, force the filter to accept inputs in the RGB
7769 color space. Default value is 0. This option is deprecated, use
7770 @option{format} instead.
7773 If set to 1, force the filter to draw the last overlay frame over the
7774 main input until the end of the stream. A value of 0 disables this
7775 behavior. Default value is 1.
7778 The @option{x}, and @option{y} expressions can contain the following
7784 The main input width and height.
7788 The overlay input width and height.
7792 The computed values for @var{x} and @var{y}. They are evaluated for
7797 horizontal and vertical chroma subsample values of the output
7798 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
7802 the number of input frame, starting from 0
7805 the position in the file of the input frame, NAN if unknown
7808 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
7812 Note that the @var{n}, @var{pos}, @var{t} variables are available only
7813 when evaluation is done @emph{per frame}, and will evaluate to NAN
7814 when @option{eval} is set to @samp{init}.
7816 Be aware that frames are taken from each input video in timestamp
7817 order, hence, if their initial timestamps differ, it is a good idea
7818 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
7819 have them begin in the same zero timestamp, as the example for
7820 the @var{movie} filter does.
7822 You can chain together more overlays but you should test the
7823 efficiency of such approach.
7825 @subsection Commands
7827 This filter supports the following commands:
7831 Modify the x and y of the overlay input.
7832 The command accepts the same syntax of the corresponding option.
7834 If the specified expression is not valid, it is kept at its current
7838 @subsection Examples
7842 Draw the overlay at 10 pixels from the bottom right corner of the main
7845 overlay=main_w-overlay_w-10:main_h-overlay_h-10
7848 Using named options the example above becomes:
7850 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
7854 Insert a transparent PNG logo in the bottom left corner of the input,
7855 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
7857 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
7861 Insert 2 different transparent PNG logos (second logo on bottom
7862 right corner) using the @command{ffmpeg} tool:
7864 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
7868 Add a transparent color layer on top of the main video; @code{WxH}
7869 must specify the size of the main input to the overlay filter:
7871 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
7875 Play an original video and a filtered version (here with the deshake
7876 filter) side by side using the @command{ffplay} tool:
7878 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
7881 The above command is the same as:
7883 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
7887 Make a sliding overlay appearing from the left to the right top part of the
7888 screen starting since time 2:
7890 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
7894 Compose output by putting two input videos side to side:
7896 ffmpeg -i left.avi -i right.avi -filter_complex "
7897 nullsrc=size=200x100 [background];
7898 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
7899 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
7900 [background][left] overlay=shortest=1 [background+left];
7901 [background+left][right] overlay=shortest=1:x=100 [left+right]
7906 Mask 10-20 seconds of a video by applying the delogo filter to a section
7908 ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
7909 -vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
7914 Chain several overlays in cascade:
7916 nullsrc=s=200x200 [bg];
7917 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
7918 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
7919 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
7920 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
7921 [in3] null, [mid2] overlay=100:100 [out0]
7928 Apply Overcomplete Wavelet denoiser.
7930 The filter accepts the following options:
7936 Larger depth values will denoise lower frequency components more, but
7937 slow down filtering.
7939 Must be an int in the range 8-16, default is @code{8}.
7941 @item luma_strength, ls
7944 Must be a double value in the range 0-1000, default is @code{1.0}.
7946 @item chroma_strength, cs
7947 Set chroma strength.
7949 Must be a double value in the range 0-1000, default is @code{1.0}.
7955 Add paddings to the input image, and place the original input at the
7956 provided @var{x}, @var{y} coordinates.
7958 It accepts the following parameters:
7963 Specify an expression for the size of the output image with the
7964 paddings added. If the value for @var{width} or @var{height} is 0, the
7965 corresponding input size is used for the output.
7967 The @var{width} expression can reference the value set by the
7968 @var{height} expression, and vice versa.
7970 The default value of @var{width} and @var{height} is 0.
7974 Specify the offsets to place the input image at within the padded area,
7975 with respect to the top/left border of the output image.
7977 The @var{x} expression can reference the value set by the @var{y}
7978 expression, and vice versa.
7980 The default value of @var{x} and @var{y} is 0.
7983 Specify the color of the padded area. For the syntax of this option,
7984 check the "Color" section in the ffmpeg-utils manual.
7986 The default value of @var{color} is "black".
7989 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
7990 options are expressions containing the following constants:
7995 The input video width and height.
7999 These are the same as @var{in_w} and @var{in_h}.
8003 The output width and height (the size of the padded area), as
8004 specified by the @var{width} and @var{height} expressions.
8008 These are the same as @var{out_w} and @var{out_h}.
8012 The x and y offsets as specified by the @var{x} and @var{y}
8013 expressions, or NAN if not yet specified.
8016 same as @var{iw} / @var{ih}
8019 input sample aspect ratio
8022 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
8026 The horizontal and vertical chroma subsample values. For example for the
8027 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
8030 @subsection Examples
8034 Add paddings with the color "violet" to the input video. The output video
8035 size is 640x480, and the top-left corner of the input video is placed at
8038 pad=640:480:0:40:violet
8041 The example above is equivalent to the following command:
8043 pad=width=640:height=480:x=0:y=40:color=violet
8047 Pad the input to get an output with dimensions increased by 3/2,
8048 and put the input video at the center of the padded area:
8050 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
8054 Pad the input to get a squared output with size equal to the maximum
8055 value between the input width and height, and put the input video at
8056 the center of the padded area:
8058 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
8062 Pad the input to get a final w/h ratio of 16:9:
8064 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
8068 In case of anamorphic video, in order to set the output display aspect
8069 correctly, it is necessary to use @var{sar} in the expression,
8070 according to the relation:
8072 (ih * X / ih) * sar = output_dar
8073 X = output_dar / sar
8076 Thus the previous example needs to be modified to:
8078 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
8082 Double the output size and put the input video in the bottom-right
8083 corner of the output padded area:
8085 pad="2*iw:2*ih:ow-iw:oh-ih"
8092 Generate one palette for a whole video stream.
8094 It accepts the following options:
8098 Set the maximum number of colors to quantize in the palette.
8099 Note: the palette will still contain 256 colors; the unused palette entries
8102 @item reserve_transparent
8103 Create a palette of 255 colors maximum and reserve the last one for
8104 transparency. Reserving the transparency color is useful for GIF optimization.
8105 If not set, the maximum of colors in the palette will be 256. You probably want
8106 to disable this option for a standalone image.
8110 Set statistics mode.
8112 It accepts the following values:
8115 Compute full frame histograms.
8117 Compute histograms only for the part that differs from previous frame. This
8118 might be relevant to give more importance to the moving part of your input if
8119 the background is static.
8122 Default value is @var{full}.
8125 The filter also exports the frame metadata @code{lavfi.color_quant_ratio}
8126 (@code{nb_color_in / nb_color_out}) which you can use to evaluate the degree of
8127 color quantization of the palette. This information is also visible at
8128 @var{info} logging level.
8130 @subsection Examples
8134 Generate a representative palette of a given video using @command{ffmpeg}:
8136 ffmpeg -i input.mkv -vf palettegen palette.png
8142 Use a palette to downsample an input video stream.
8144 The filter takes two inputs: one video stream and a palette. The palette must
8145 be a 256 pixels image.
8147 It accepts the following options:
8151 Select dithering mode. Available algorithms are:
8154 Ordered 8x8 bayer dithering (deterministic)
8156 Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
8157 Note: this dithering is sometimes considered "wrong" and is included as a
8159 @item floyd_steinberg
8160 Floyd and Steingberg dithering (error diffusion)
8162 Frankie Sierra dithering v2 (error diffusion)
8164 Frankie Sierra dithering v2 "Lite" (error diffusion)
8167 Default is @var{sierra2_4a}.
8170 When @var{bayer} dithering is selected, this option defines the scale of the
8171 pattern (how much the crosshatch pattern is visible). A low value means more
8172 visible pattern for less banding, and higher value means less visible pattern
8173 at the cost of more banding.
8175 The option must be an integer value in the range [0,5]. Default is @var{2}.
8178 If set, define the zone to process
8182 Only the changing rectangle will be reprocessed. This is similar to GIF
8183 cropping/offsetting compression mechanism. This option can be useful for speed
8184 if only a part of the image is changing, and has use cases such as limiting the
8185 scope of the error diffusal @option{dither} to the rectangle that bounds the
8186 moving scene (it leads to more deterministic output if the scene doesn't change
8187 much, and as a result less moving noise and better GIF compression).
8190 Default is @var{none}.
8193 @subsection Examples
8197 Use a palette (generated for example with @ref{palettegen}) to encode a GIF
8198 using @command{ffmpeg}:
8200 ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
8204 @section perspective
8206 Correct perspective of video not recorded perpendicular to the screen.
8208 A description of the accepted parameters follows.
8219 Set coordinates expression for top left, top right, bottom left and bottom right corners.
8220 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
8221 If the @code{sense} option is set to @code{source}, then the specified points will be sent
8222 to the corners of the destination. If the @code{sense} option is set to @code{destination},
8223 then the corners of the source will be sent to the specified coordinates.
8225 The expressions can use the following variables:
8230 the width and height of video frame.
8234 Set interpolation for perspective correction.
8236 It accepts the following values:
8242 Default value is @samp{linear}.
8245 Set interpretation of coordinate options.
8247 It accepts the following values:
8251 Send point in the source specified by the given coordinates to
8252 the corners of the destination.
8254 @item 1, destination
8256 Send the corners of the source to the point in the destination specified
8257 by the given coordinates.
8259 Default value is @samp{source}.
8265 Delay interlaced video by one field time so that the field order changes.
8267 The intended use is to fix PAL movies that have been captured with the
8268 opposite field order to the film-to-video transfer.
8270 A description of the accepted parameters follows.
8276 It accepts the following values:
8279 Capture field order top-first, transfer bottom-first.
8280 Filter will delay the bottom field.
8283 Capture field order bottom-first, transfer top-first.
8284 Filter will delay the top field.
8287 Capture and transfer with the same field order. This mode only exists
8288 for the documentation of the other options to refer to, but if you
8289 actually select it, the filter will faithfully do nothing.
8292 Capture field order determined automatically by field flags, transfer
8294 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
8295 basis using field flags. If no field information is available,
8296 then this works just like @samp{u}.
8299 Capture unknown or varying, transfer opposite.
8300 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
8301 analyzing the images and selecting the alternative that produces best
8302 match between the fields.
8305 Capture top-first, transfer unknown or varying.
8306 Filter selects among @samp{t} and @samp{p} using image analysis.
8309 Capture bottom-first, transfer unknown or varying.
8310 Filter selects among @samp{b} and @samp{p} using image analysis.
8313 Capture determined by field flags, transfer unknown or varying.
8314 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
8315 image analysis. If no field information is available, then this works just
8316 like @samp{U}. This is the default mode.
8319 Both capture and transfer unknown or varying.
8320 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
8324 @section pixdesctest
8326 Pixel format descriptor test filter, mainly useful for internal
8327 testing. The output video should be equal to the input video.
8331 format=monow, pixdesctest
8334 can be used to test the monowhite pixel format descriptor definition.
8338 Enable the specified chain of postprocessing subfilters using libpostproc. This
8339 library should be automatically selected with a GPL build (@code{--enable-gpl}).
8340 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
8341 Each subfilter and some options have a short and a long name that can be used
8342 interchangeably, i.e. dr/dering are the same.
8344 The filters accept the following options:
8348 Set postprocessing subfilters string.
8351 All subfilters share common options to determine their scope:
8355 Honor the quality commands for this subfilter.
8358 Do chrominance filtering, too (default).
8361 Do luminance filtering only (no chrominance).
8364 Do chrominance filtering only (no luminance).
8367 These options can be appended after the subfilter name, separated by a '|'.
8369 Available subfilters are:
8372 @item hb/hdeblock[|difference[|flatness]]
8373 Horizontal deblocking filter
8376 Difference factor where higher values mean more deblocking (default: @code{32}).
8378 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8381 @item vb/vdeblock[|difference[|flatness]]
8382 Vertical deblocking filter
8385 Difference factor where higher values mean more deblocking (default: @code{32}).
8387 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8390 @item ha/hadeblock[|difference[|flatness]]
8391 Accurate horizontal deblocking filter
8394 Difference factor where higher values mean more deblocking (default: @code{32}).
8396 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8399 @item va/vadeblock[|difference[|flatness]]
8400 Accurate vertical deblocking filter
8403 Difference factor where higher values mean more deblocking (default: @code{32}).
8405 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8409 The horizontal and vertical deblocking filters share the difference and
8410 flatness values so you cannot set different horizontal and vertical
8415 Experimental horizontal deblocking filter
8418 Experimental vertical deblocking filter
8423 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
8426 larger -> stronger filtering
8428 larger -> stronger filtering
8430 larger -> stronger filtering
8433 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
8436 Stretch luminance to @code{0-255}.
8439 @item lb/linblenddeint
8440 Linear blend deinterlacing filter that deinterlaces the given block by
8441 filtering all lines with a @code{(1 2 1)} filter.
8443 @item li/linipoldeint
8444 Linear interpolating deinterlacing filter that deinterlaces the given block by
8445 linearly interpolating every second line.
8447 @item ci/cubicipoldeint
8448 Cubic interpolating deinterlacing filter deinterlaces the given block by
8449 cubically interpolating every second line.
8451 @item md/mediandeint
8452 Median deinterlacing filter that deinterlaces the given block by applying a
8453 median filter to every second line.
8455 @item fd/ffmpegdeint
8456 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
8457 second line with a @code{(-1 4 2 4 -1)} filter.
8460 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
8461 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
8463 @item fq/forceQuant[|quantizer]
8464 Overrides the quantizer table from the input with the constant quantizer you
8472 Default pp filter combination (@code{hb|a,vb|a,dr|a})
8475 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
8478 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
8481 @subsection Examples
8485 Apply horizontal and vertical deblocking, deringing and automatic
8486 brightness/contrast:
8492 Apply default filters without brightness/contrast correction:
8498 Apply default filters and temporal denoiser:
8500 pp=default/tmpnoise|1|2|3
8504 Apply deblocking on luminance only, and switch vertical deblocking on or off
8505 automatically depending on available CPU time:
8512 Apply Postprocessing filter 7. It is variant of the @ref{spp} filter,
8513 similar to spp = 6 with 7 point DCT, where only the center sample is
8516 The filter accepts the following options:
8520 Force a constant quantization parameter. It accepts an integer in range
8521 0 to 63. If not set, the filter will use the QP from the video stream
8525 Set thresholding mode. Available modes are:
8529 Set hard thresholding.
8531 Set soft thresholding (better de-ringing effect, but likely blurrier).
8533 Set medium thresholding (good results, default).
8539 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
8540 Ratio) between two input videos.
8542 This filter takes in input two input videos, the first input is
8543 considered the "main" source and is passed unchanged to the
8544 output. The second input is used as a "reference" video for computing
8547 Both video inputs must have the same resolution and pixel format for
8548 this filter to work correctly. Also it assumes that both inputs
8549 have the same number of frames, which are compared one by one.
8551 The obtained average PSNR is printed through the logging system.
8553 The filter stores the accumulated MSE (mean squared error) of each
8554 frame, and at the end of the processing it is averaged across all frames
8555 equally, and the following formula is applied to obtain the PSNR:
8558 PSNR = 10*log10(MAX^2/MSE)
8561 Where MAX is the average of the maximum values of each component of the
8564 The description of the accepted parameters follows.
8568 If specified the filter will use the named file to save the PSNR of
8569 each individual frame.
8572 The file printed if @var{stats_file} is selected, contains a sequence of
8573 key/value pairs of the form @var{key}:@var{value} for each compared
8576 A description of each shown parameter follows:
8580 sequential number of the input frame, starting from 1
8583 Mean Square Error pixel-by-pixel average difference of the compared
8584 frames, averaged over all the image components.
8586 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
8587 Mean Square Error pixel-by-pixel average difference of the compared
8588 frames for the component specified by the suffix.
8590 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
8591 Peak Signal to Noise ratio of the compared frames for the component
8592 specified by the suffix.
8597 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
8598 [main][ref] psnr="stats_file=stats.log" [out]
8601 On this example the input file being processed is compared with the
8602 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
8603 is stored in @file{stats.log}.
8608 Pulldown reversal (inverse telecine) filter, capable of handling mixed
8609 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
8612 The pullup filter is designed to take advantage of future context in making
8613 its decisions. This filter is stateless in the sense that it does not lock
8614 onto a pattern to follow, but it instead looks forward to the following
8615 fields in order to identify matches and rebuild progressive frames.
8617 To produce content with an even framerate, insert the fps filter after
8618 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
8619 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
8621 The filter accepts the following options:
8628 These options set the amount of "junk" to ignore at the left, right, top, and
8629 bottom of the image, respectively. Left and right are in units of 8 pixels,
8630 while top and bottom are in units of 2 lines.
8631 The default is 8 pixels on each side.
8634 Set the strict breaks. Setting this option to 1 will reduce the chances of
8635 filter generating an occasional mismatched frame, but it may also cause an
8636 excessive number of frames to be dropped during high motion sequences.
8637 Conversely, setting it to -1 will make filter match fields more easily.
8638 This may help processing of video where there is slight blurring between
8639 the fields, but may also cause there to be interlaced frames in the output.
8640 Default value is @code{0}.
8643 Set the metric plane to use. It accepts the following values:
8649 Use chroma blue plane.
8652 Use chroma red plane.
8655 This option may be set to use chroma plane instead of the default luma plane
8656 for doing filter's computations. This may improve accuracy on very clean
8657 source material, but more likely will decrease accuracy, especially if there
8658 is chroma noise (rainbow effect) or any grayscale video.
8659 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
8660 load and make pullup usable in realtime on slow machines.
8663 For best results (without duplicated frames in the output file) it is
8664 necessary to change the output frame rate. For example, to inverse
8665 telecine NTSC input:
8667 ffmpeg -i input -vf pullup -r 24000/1001 ...
8672 Change video quantization parameters (QP).
8674 The filter accepts the following option:
8678 Set expression for quantization parameter.
8681 The expression is evaluated through the eval API and can contain, among others,
8682 the following constants:
8686 1 if index is not 129, 0 otherwise.
8689 Sequentional index starting from -129 to 128.
8692 @subsection Examples
8704 Flush video frames from internal cache of frames into a random order.
8705 No frame is discarded.
8706 Inspired by @ref{frei0r} nervous filter.
8710 Set size in number of frames of internal cache, in range from @code{2} to
8711 @code{512}. Default is @code{30}.
8714 Set seed for random number generator, must be an integer included between
8715 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
8716 less than @code{0}, the filter will try to use a good random seed on a
8720 @section removegrain
8722 The removegrain filter is a spatial denoiser for progressive video.
8726 Set mode for the first plane.
8729 Set mode for the second plane.
8732 Set mode for the third plane.
8735 Set mode for the fourth plane.
8738 Range of mode is from 0 to 24. Description of each mode follows:
8742 Leave input plane unchanged. Default.
8745 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
8748 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
8751 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
8754 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
8755 This is equivalent to a median filter.
8758 Line-sensitive clipping giving the minimal change.
8761 Line-sensitive clipping, intermediate.
8764 Line-sensitive clipping, intermediate.
8767 Line-sensitive clipping, intermediate.
8770 Line-sensitive clipping on a line where the neighbours pixels are the closest.
8773 Replaces the target pixel with the closest neighbour.
8776 [1 2 1] horizontal and vertical kernel blur.
8782 Bob mode, interpolates top field from the line where the neighbours
8783 pixels are the closest.
8786 Bob mode, interpolates bottom field from the line where the neighbours
8787 pixels are the closest.
8790 Bob mode, interpolates top field. Same as 13 but with a more complicated
8791 interpolation formula.
8794 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
8795 interpolation formula.
8798 Clips the pixel with the minimum and maximum of respectively the maximum and
8799 minimum of each pair of opposite neighbour pixels.
8802 Line-sensitive clipping using opposite neighbours whose greatest distance from
8803 the current pixel is minimal.
8806 Replaces the pixel with the average of its 8 neighbours.
8809 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
8812 Clips pixels using the averages of opposite neighbour.
8815 Same as mode 21 but simpler and faster.
8818 Small edge and halo removal, but reputed useless.
8826 Suppress a TV station logo, using an image file to determine which
8827 pixels comprise the logo. It works by filling in the pixels that
8828 comprise the logo with neighboring pixels.
8830 The filter accepts the following options:
8834 Set the filter bitmap file, which can be any image format supported by
8835 libavformat. The width and height of the image file must match those of the
8836 video stream being processed.
8839 Pixels in the provided bitmap image with a value of zero are not
8840 considered part of the logo, non-zero pixels are considered part of
8841 the logo. If you use white (255) for the logo and black (0) for the
8842 rest, you will be safe. For making the filter bitmap, it is
8843 recommended to take a screen capture of a black frame with the logo
8844 visible, and then using a threshold filter followed by the erode
8845 filter once or twice.
8847 If needed, little splotches can be fixed manually. Remember that if
8848 logo pixels are not covered, the filter quality will be much
8849 reduced. Marking too many pixels as part of the logo does not hurt as
8850 much, but it will increase the amount of blurring needed to cover over
8851 the image and will destroy more information than necessary, and extra
8852 pixels will slow things down on a large logo.
8854 @section repeatfields
8856 This filter uses the repeat_field flag from the Video ES headers and hard repeats
8857 fields based on its value.
8859 @section reverse, areverse
8863 Warning: This filter requires memory to buffer the entire clip, so trimming
8866 @subsection Examples
8870 Take the first 5 seconds of a clip, and reverse it.
8878 Rotate video by an arbitrary angle expressed in radians.
8880 The filter accepts the following options:
8882 A description of the optional parameters follows.
8885 Set an expression for the angle by which to rotate the input video
8886 clockwise, expressed as a number of radians. A negative value will
8887 result in a counter-clockwise rotation. By default it is set to "0".
8889 This expression is evaluated for each frame.
8892 Set the output width expression, default value is "iw".
8893 This expression is evaluated just once during configuration.
8896 Set the output height expression, default value is "ih".
8897 This expression is evaluated just once during configuration.
8900 Enable bilinear interpolation if set to 1, a value of 0 disables
8901 it. Default value is 1.
8904 Set the color used to fill the output area not covered by the rotated
8905 image. For the general syntax of this option, check the "Color" section in the
8906 ffmpeg-utils manual. If the special value "none" is selected then no
8907 background is printed (useful for example if the background is never shown).
8909 Default value is "black".
8912 The expressions for the angle and the output size can contain the
8913 following constants and functions:
8917 sequential number of the input frame, starting from 0. It is always NAN
8918 before the first frame is filtered.
8921 time in seconds of the input frame, it is set to 0 when the filter is
8922 configured. It is always NAN before the first frame is filtered.
8926 horizontal and vertical chroma subsample values. For example for the
8927 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
8931 the input video width and height
8935 the output width and height, that is the size of the padded area as
8936 specified by the @var{width} and @var{height} expressions
8940 the minimal width/height required for completely containing the input
8941 video rotated by @var{a} radians.
8943 These are only available when computing the @option{out_w} and
8944 @option{out_h} expressions.
8947 @subsection Examples
8951 Rotate the input by PI/6 radians clockwise:
8957 Rotate the input by PI/6 radians counter-clockwise:
8963 Rotate the input by 45 degrees clockwise:
8969 Apply a constant rotation with period T, starting from an angle of PI/3:
8971 rotate=PI/3+2*PI*t/T
8975 Make the input video rotation oscillating with a period of T
8976 seconds and an amplitude of A radians:
8978 rotate=A*sin(2*PI/T*t)
8982 Rotate the video, output size is chosen so that the whole rotating
8983 input video is always completely contained in the output:
8985 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
8989 Rotate the video, reduce the output size so that no background is ever
8992 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
8996 @subsection Commands
8998 The filter supports the following commands:
9002 Set the angle expression.
9003 The command accepts the same syntax of the corresponding option.
9005 If the specified expression is not valid, it is kept at its current
9011 Apply Shape Adaptive Blur.
9013 The filter accepts the following options:
9016 @item luma_radius, lr
9017 Set luma blur filter strength, must be a value in range 0.1-4.0, default
9018 value is 1.0. A greater value will result in a more blurred image, and
9019 in slower processing.
9021 @item luma_pre_filter_radius, lpfr
9022 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
9025 @item luma_strength, ls
9026 Set luma maximum difference between pixels to still be considered, must
9027 be a value in the 0.1-100.0 range, default value is 1.0.
9029 @item chroma_radius, cr
9030 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
9031 greater value will result in a more blurred image, and in slower
9034 @item chroma_pre_filter_radius, cpfr
9035 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
9037 @item chroma_strength, cs
9038 Set chroma maximum difference between pixels to still be considered,
9039 must be a value in the 0.1-100.0 range.
9042 Each chroma option value, if not explicitly specified, is set to the
9043 corresponding luma option value.
9048 Scale (resize) the input video, using the libswscale library.
9050 The scale filter forces the output display aspect ratio to be the same
9051 of the input, by changing the output sample aspect ratio.
9053 If the input image format is different from the format requested by
9054 the next filter, the scale filter will convert the input to the
9058 The filter accepts the following options, or any of the options
9059 supported by the libswscale scaler.
9061 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
9062 the complete list of scaler options.
9067 Set the output video dimension expression. Default value is the input
9070 If the value is 0, the input width is used for the output.
9072 If one of the values is -1, the scale filter will use a value that
9073 maintains the aspect ratio of the input image, calculated from the
9074 other specified dimension. If both of them are -1, the input size is
9077 If one of the values is -n with n > 1, the scale filter will also use a value
9078 that maintains the aspect ratio of the input image, calculated from the other
9079 specified dimension. After that it will, however, make sure that the calculated
9080 dimension is divisible by n and adjust the value if necessary.
9082 See below for the list of accepted constants for use in the dimension
9086 Set the interlacing mode. It accepts the following values:
9090 Force interlaced aware scaling.
9093 Do not apply interlaced scaling.
9096 Select interlaced aware scaling depending on whether the source frames
9097 are flagged as interlaced or not.
9100 Default value is @samp{0}.
9103 Set libswscale scaling flags. See
9104 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
9105 complete list of values. If not explicitly specified the filter applies
9109 Set the video size. For the syntax of this option, check the
9110 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9112 @item in_color_matrix
9113 @item out_color_matrix
9114 Set in/output YCbCr color space type.
9116 This allows the autodetected value to be overridden as well as allows forcing
9117 a specific value used for the output and encoder.
9119 If not specified, the color space type depends on the pixel format.
9125 Choose automatically.
9128 Format conforming to International Telecommunication Union (ITU)
9129 Recommendation BT.709.
9132 Set color space conforming to the United States Federal Communications
9133 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
9136 Set color space conforming to:
9140 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
9143 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
9146 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
9151 Set color space conforming to SMPTE ST 240:1999.
9156 Set in/output YCbCr sample range.
9158 This allows the autodetected value to be overridden as well as allows forcing
9159 a specific value used for the output and encoder. If not specified, the
9160 range depends on the pixel format. Possible values:
9164 Choose automatically.
9167 Set full range (0-255 in case of 8-bit luma).
9170 Set "MPEG" range (16-235 in case of 8-bit luma).
9173 @item force_original_aspect_ratio
9174 Enable decreasing or increasing output video width or height if necessary to
9175 keep the original aspect ratio. Possible values:
9179 Scale the video as specified and disable this feature.
9182 The output video dimensions will automatically be decreased if needed.
9185 The output video dimensions will automatically be increased if needed.
9189 One useful instance of this option is that when you know a specific device's
9190 maximum allowed resolution, you can use this to limit the output video to
9191 that, while retaining the aspect ratio. For example, device A allows
9192 1280x720 playback, and your video is 1920x800. Using this option (set it to
9193 decrease) and specifying 1280x720 to the command line makes the output
9196 Please note that this is a different thing than specifying -1 for @option{w}
9197 or @option{h}, you still need to specify the output resolution for this option
9202 The values of the @option{w} and @option{h} options are expressions
9203 containing the following constants:
9208 The input width and height
9212 These are the same as @var{in_w} and @var{in_h}.
9216 The output (scaled) width and height
9220 These are the same as @var{out_w} and @var{out_h}
9223 The same as @var{iw} / @var{ih}
9226 input sample aspect ratio
9229 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
9233 horizontal and vertical input chroma subsample values. For example for the
9234 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9238 horizontal and vertical output chroma subsample values. For example for the
9239 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9242 @subsection Examples
9246 Scale the input video to a size of 200x100
9251 This is equivalent to:
9262 Specify a size abbreviation for the output size:
9267 which can also be written as:
9273 Scale the input to 2x:
9279 The above is the same as:
9285 Scale the input to 2x with forced interlaced scaling:
9287 scale=2*iw:2*ih:interl=1
9291 Scale the input to half size:
9297 Increase the width, and set the height to the same size:
9310 Increase the height, and set the width to 3/2 of the height:
9312 scale=w=3/2*oh:h=3/5*ih
9316 Increase the size, making the size a multiple of the chroma
9319 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
9323 Increase the width to a maximum of 500 pixels,
9324 keeping the same aspect ratio as the input:
9326 scale=w='min(500\, iw*3/2):h=-1'
9330 @subsection Commands
9332 This filter supports the following commands:
9336 Set the output video dimension expression.
9337 The command accepts the same syntax of the corresponding option.
9339 If the specified expression is not valid, it is kept at its current
9345 Scale (resize) the input video, based on a reference video.
9347 See the scale filter for available options, scale2ref supports the same but
9348 uses the reference video instead of the main input as basis.
9350 @subsection Examples
9354 Scale a subtitle stream to match the main video in size before overlaying
9356 'scale2ref[b][a];[a][b]overlay'
9360 @section separatefields
9362 The @code{separatefields} takes a frame-based video input and splits
9363 each frame into its components fields, producing a new half height clip
9364 with twice the frame rate and twice the frame count.
9366 This filter use field-dominance information in frame to decide which
9367 of each pair of fields to place first in the output.
9368 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
9370 @section setdar, setsar
9372 The @code{setdar} filter sets the Display Aspect Ratio for the filter
9375 This is done by changing the specified Sample (aka Pixel) Aspect
9376 Ratio, according to the following equation:
9378 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
9381 Keep in mind that the @code{setdar} filter does not modify the pixel
9382 dimensions of the video frame. Also, the display aspect ratio set by
9383 this filter may be changed by later filters in the filterchain,
9384 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
9387 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
9388 the filter output video.
9390 Note that as a consequence of the application of this filter, the
9391 output display aspect ratio will change according to the equation
9394 Keep in mind that the sample aspect ratio set by the @code{setsar}
9395 filter may be changed by later filters in the filterchain, e.g. if
9396 another "setsar" or a "setdar" filter is applied.
9398 It accepts the following parameters:
9401 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
9402 Set the aspect ratio used by the filter.
9404 The parameter can be a floating point number string, an expression, or
9405 a string of the form @var{num}:@var{den}, where @var{num} and
9406 @var{den} are the numerator and denominator of the aspect ratio. If
9407 the parameter is not specified, it is assumed the value "0".
9408 In case the form "@var{num}:@var{den}" is used, the @code{:} character
9412 Set the maximum integer value to use for expressing numerator and
9413 denominator when reducing the expressed aspect ratio to a rational.
9414 Default value is @code{100}.
9418 The parameter @var{sar} is an expression containing
9419 the following constants:
9423 These are approximated values for the mathematical constants e
9424 (Euler's number), pi (Greek pi), and phi (the golden ratio).
9427 The input width and height.
9430 These are the same as @var{w} / @var{h}.
9433 The input sample aspect ratio.
9436 The input display aspect ratio. It is the same as
9437 (@var{w} / @var{h}) * @var{sar}.
9440 Horizontal and vertical chroma subsample values. For example, for the
9441 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9444 @subsection Examples
9449 To change the display aspect ratio to 16:9, specify one of the following:
9457 To change the sample aspect ratio to 10:11, specify:
9463 To set a display aspect ratio of 16:9, and specify a maximum integer value of
9464 1000 in the aspect ratio reduction, use the command:
9466 setdar=ratio=16/9:max=1000
9474 Force field for the output video frame.
9476 The @code{setfield} filter marks the interlace type field for the
9477 output frames. It does not change the input frame, but only sets the
9478 corresponding property, which affects how the frame is treated by
9479 following filters (e.g. @code{fieldorder} or @code{yadif}).
9481 The filter accepts the following options:
9486 Available values are:
9490 Keep the same field property.
9493 Mark the frame as bottom-field-first.
9496 Mark the frame as top-field-first.
9499 Mark the frame as progressive.
9505 Show a line containing various information for each input video frame.
9506 The input video is not modified.
9508 The shown line contains a sequence of key/value pairs of the form
9509 @var{key}:@var{value}.
9511 The following values are shown in the output:
9515 The (sequential) number of the input frame, starting from 0.
9518 The Presentation TimeStamp of the input frame, expressed as a number of
9519 time base units. The time base unit depends on the filter input pad.
9522 The Presentation TimeStamp of the input frame, expressed as a number of
9526 The position of the frame in the input stream, or -1 if this information is
9527 unavailable and/or meaningless (for example in case of synthetic video).
9530 The pixel format name.
9533 The sample aspect ratio of the input frame, expressed in the form
9534 @var{num}/@var{den}.
9537 The size of the input frame. For the syntax of this option, check the
9538 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9541 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
9542 for bottom field first).
9545 This is 1 if the frame is a key frame, 0 otherwise.
9548 The picture type of the input frame ("I" for an I-frame, "P" for a
9549 P-frame, "B" for a B-frame, or "?" for an unknown type).
9550 Also refer to the documentation of the @code{AVPictureType} enum and of
9551 the @code{av_get_picture_type_char} function defined in
9552 @file{libavutil/avutil.h}.
9555 The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
9557 @item plane_checksum
9558 The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
9559 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]".
9562 @section showpalette
9564 Displays the 256 colors palette of each frame. This filter is only relevant for
9565 @var{pal8} pixel format frames.
9567 It accepts the following option:
9571 Set the size of the box used to represent one palette color entry. Default is
9572 @code{30} (for a @code{30x30} pixel box).
9575 @section shuffleplanes
9577 Reorder and/or duplicate video planes.
9579 It accepts the following parameters:
9584 The index of the input plane to be used as the first output plane.
9587 The index of the input plane to be used as the second output plane.
9590 The index of the input plane to be used as the third output plane.
9593 The index of the input plane to be used as the fourth output plane.
9597 The first plane has the index 0. The default is to keep the input unchanged.
9599 Swap the second and third planes of the input:
9601 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
9604 @anchor{signalstats}
9605 @section signalstats
9606 Evaluate various visual metrics that assist in determining issues associated
9607 with the digitization of analog video media.
9609 By default the filter will log these metadata values:
9613 Display the minimal Y value contained within the input frame. Expressed in
9617 Display the Y value at the 10% percentile within the input frame. Expressed in
9621 Display the average Y value within the input frame. Expressed in range of
9625 Display the Y value at the 90% percentile within the input frame. Expressed in
9629 Display the maximum Y value contained within the input frame. Expressed in
9633 Display the minimal U value contained within the input frame. Expressed in
9637 Display the U value at the 10% percentile within the input frame. Expressed in
9641 Display the average U value within the input frame. Expressed in range of
9645 Display the U value at the 90% percentile within the input frame. Expressed in
9649 Display the maximum U value contained within the input frame. Expressed in
9653 Display the minimal V value contained within the input frame. Expressed in
9657 Display the V value at the 10% percentile within the input frame. Expressed in
9661 Display the average V value within the input frame. Expressed in range of
9665 Display the V value at the 90% percentile within the input frame. Expressed in
9669 Display the maximum V value contained within the input frame. Expressed in
9673 Display the minimal saturation value contained within the input frame.
9674 Expressed in range of [0-~181.02].
9677 Display the saturation value at the 10% percentile within the input frame.
9678 Expressed in range of [0-~181.02].
9681 Display the average saturation value within the input frame. Expressed in range
9685 Display the saturation value at the 90% percentile within the input frame.
9686 Expressed in range of [0-~181.02].
9689 Display the maximum saturation value contained within the input frame.
9690 Expressed in range of [0-~181.02].
9693 Display the median value for hue within the input frame. Expressed in range of
9697 Display the average value for hue within the input frame. Expressed in range of
9701 Display the average of sample value difference between all values of the Y
9702 plane in the current frame and corresponding values of the previous input frame.
9703 Expressed in range of [0-255].
9706 Display the average of sample value difference between all values of the U
9707 plane in the current frame and corresponding values of the previous input frame.
9708 Expressed in range of [0-255].
9711 Display the average of sample value difference between all values of the V
9712 plane in the current frame and corresponding values of the previous input frame.
9713 Expressed in range of [0-255].
9716 The filter accepts the following options:
9722 @option{stat} specify an additional form of image analysis.
9723 @option{out} output video with the specified type of pixel highlighted.
9725 Both options accept the following values:
9729 Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel
9730 unlike the neighboring pixels of the same field. Examples of temporal outliers
9731 include the results of video dropouts, head clogs, or tape tracking issues.
9734 Identify @var{vertical line repetition}. Vertical line repetition includes
9735 similar rows of pixels within a frame. In born-digital video vertical line
9736 repetition is common, but this pattern is uncommon in video digitized from an
9737 analog source. When it occurs in video that results from the digitization of an
9738 analog source it can indicate concealment from a dropout compensator.
9741 Identify pixels that fall outside of legal broadcast range.
9745 Set the highlight color for the @option{out} option. The default color is
9749 @subsection Examples
9753 Output data of various video metrics:
9755 ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
9759 Output specific data about the minimum and maximum values of the Y plane per frame:
9761 ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
9765 Playback video while highlighting pixels that are outside of broadcast range in red.
9767 ffplay example.mov -vf signalstats="out=brng:color=red"
9771 Playback video with signalstats metadata drawn over the frame.
9773 ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
9776 The contents of signalstat_drawtext.txt used in the command are:
9779 Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@})
9780 U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@})
9781 V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@})
9782 saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@}
9790 Blur the input video without impacting the outlines.
9792 It accepts the following options:
9795 @item luma_radius, lr
9796 Set the luma radius. The option value must be a float number in
9797 the range [0.1,5.0] that specifies the variance of the gaussian filter
9798 used to blur the image (slower if larger). Default value is 1.0.
9800 @item luma_strength, ls
9801 Set the luma strength. The option value must be a float number
9802 in the range [-1.0,1.0] that configures the blurring. A value included
9803 in [0.0,1.0] will blur the image whereas a value included in
9804 [-1.0,0.0] will sharpen the image. Default value is 1.0.
9806 @item luma_threshold, lt
9807 Set the luma threshold used as a coefficient to determine
9808 whether a pixel should be blurred or not. The option value must be an
9809 integer in the range [-30,30]. A value of 0 will filter all the image,
9810 a value included in [0,30] will filter flat areas and a value included
9811 in [-30,0] will filter edges. Default value is 0.
9813 @item chroma_radius, cr
9814 Set the chroma radius. The option value must be a float number in
9815 the range [0.1,5.0] that specifies the variance of the gaussian filter
9816 used to blur the image (slower if larger). Default value is 1.0.
9818 @item chroma_strength, cs
9819 Set the chroma strength. The option value must be a float number
9820 in the range [-1.0,1.0] that configures the blurring. A value included
9821 in [0.0,1.0] will blur the image whereas a value included in
9822 [-1.0,0.0] will sharpen the image. Default value is 1.0.
9824 @item chroma_threshold, ct
9825 Set the chroma threshold used as a coefficient to determine
9826 whether a pixel should be blurred or not. The option value must be an
9827 integer in the range [-30,30]. A value of 0 will filter all the image,
9828 a value included in [0,30] will filter flat areas and a value included
9829 in [-30,0] will filter edges. Default value is 0.
9832 If a chroma option is not explicitly set, the corresponding luma value
9837 Obtain the SSIM (Structural SImilarity Metric) between two input videos.
9839 This filter takes in input two input videos, the first input is
9840 considered the "main" source and is passed unchanged to the
9841 output. The second input is used as a "reference" video for computing
9844 Both video inputs must have the same resolution and pixel format for
9845 this filter to work correctly. Also it assumes that both inputs
9846 have the same number of frames, which are compared one by one.
9848 The filter stores the calculated SSIM of each frame.
9850 The description of the accepted parameters follows.
9854 If specified the filter will use the named file to save the SSIM of
9855 each individual frame.
9858 The file printed if @var{stats_file} is selected, contains a sequence of
9859 key/value pairs of the form @var{key}:@var{value} for each compared
9862 A description of each shown parameter follows:
9866 sequential number of the input frame, starting from 1
9868 @item Y, U, V, R, G, B
9869 SSIM of the compared frames for the component specified by the suffix.
9872 SSIM of the compared frames for the whole frame.
9875 Same as above but in dB representation.
9880 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
9881 [main][ref] ssim="stats_file=stats.log" [out]
9884 On this example the input file being processed is compared with the
9885 reference file @file{ref_movie.mpg}. The SSIM of each individual frame
9886 is stored in @file{stats.log}.
9888 Another example with both psnr and ssim at same time:
9890 ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
9895 Convert between different stereoscopic image formats.
9897 The filters accept the following options:
9901 Set stereoscopic image format of input.
9903 Available values for input image formats are:
9906 side by side parallel (left eye left, right eye right)
9909 side by side crosseye (right eye left, left eye right)
9912 side by side parallel with half width resolution
9913 (left eye left, right eye right)
9916 side by side crosseye with half width resolution
9917 (right eye left, left eye right)
9920 above-below (left eye above, right eye below)
9923 above-below (right eye above, left eye below)
9926 above-below with half height resolution
9927 (left eye above, right eye below)
9930 above-below with half height resolution
9931 (right eye above, left eye below)
9934 alternating frames (left eye first, right eye second)
9937 alternating frames (right eye first, left eye second)
9940 interleaved rows (left eye has top row, right eye starts on next row)
9943 interleaved rows (right eye has top row, left eye starts on next row)
9945 Default value is @samp{sbsl}.
9949 Set stereoscopic image format of output.
9951 Available values for output image formats are all the input formats as well as:
9954 anaglyph red/blue gray
9955 (red filter on left eye, blue filter on right eye)
9958 anaglyph red/green gray
9959 (red filter on left eye, green filter on right eye)
9962 anaglyph red/cyan gray
9963 (red filter on left eye, cyan filter on right eye)
9966 anaglyph red/cyan half colored
9967 (red filter on left eye, cyan filter on right eye)
9970 anaglyph red/cyan color
9971 (red filter on left eye, cyan filter on right eye)
9974 anaglyph red/cyan color optimized with the least squares projection of dubois
9975 (red filter on left eye, cyan filter on right eye)
9978 anaglyph green/magenta gray
9979 (green filter on left eye, magenta filter on right eye)
9982 anaglyph green/magenta half colored
9983 (green filter on left eye, magenta filter on right eye)
9986 anaglyph green/magenta colored
9987 (green filter on left eye, magenta filter on right eye)
9990 anaglyph green/magenta color optimized with the least squares projection of dubois
9991 (green filter on left eye, magenta filter on right eye)
9994 anaglyph yellow/blue gray
9995 (yellow filter on left eye, blue filter on right eye)
9998 anaglyph yellow/blue half colored
9999 (yellow filter on left eye, blue filter on right eye)
10002 anaglyph yellow/blue colored
10003 (yellow filter on left eye, blue filter on right eye)
10006 anaglyph yellow/blue color optimized with the least squares projection of dubois
10007 (yellow filter on left eye, blue filter on right eye)
10010 mono output (left eye only)
10013 mono output (right eye only)
10016 checkerboard, left eye first
10019 checkerboard, right eye first
10022 interleaved columns, left eye first
10025 interleaved columns, right eye first
10028 Default value is @samp{arcd}.
10031 @subsection Examples
10035 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
10041 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
10050 Apply a simple postprocessing filter that compresses and decompresses the image
10051 at several (or - in the case of @option{quality} level @code{6} - all) shifts
10052 and average the results.
10054 The filter accepts the following options:
10058 Set quality. This option defines the number of levels for averaging. It accepts
10059 an integer in the range 0-6. If set to @code{0}, the filter will have no
10060 effect. A value of @code{6} means the higher quality. For each increment of
10061 that value the speed drops by a factor of approximately 2. Default value is
10065 Force a constant quantization parameter. If not set, the filter will use the QP
10066 from the video stream (if available).
10069 Set thresholding mode. Available modes are:
10073 Set hard thresholding (default).
10075 Set soft thresholding (better de-ringing effect, but likely blurrier).
10078 @item use_bframe_qp
10079 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
10080 option may cause flicker since the B-Frames have often larger QP. Default is
10081 @code{0} (not enabled).
10087 Draw subtitles on top of input video using the libass library.
10089 To enable compilation of this filter you need to configure FFmpeg with
10090 @code{--enable-libass}. This filter also requires a build with libavcodec and
10091 libavformat to convert the passed subtitles file to ASS (Advanced Substation
10092 Alpha) subtitles format.
10094 The filter accepts the following options:
10098 Set the filename of the subtitle file to read. It must be specified.
10100 @item original_size
10101 Specify the size of the original video, the video for which the ASS file
10102 was composed. For the syntax of this option, check the
10103 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10104 Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
10105 correctly scale the fonts if the aspect ratio has been changed.
10108 Set a directory path containing fonts that can be used by the filter.
10109 These fonts will be used in addition to whatever the font provider uses.
10112 Set subtitles input character encoding. @code{subtitles} filter only. Only
10113 useful if not UTF-8.
10115 @item stream_index, si
10116 Set subtitles stream index. @code{subtitles} filter only.
10119 Override default style or script info parameters of the subtitles. It accepts a
10120 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
10123 If the first key is not specified, it is assumed that the first value
10124 specifies the @option{filename}.
10126 For example, to render the file @file{sub.srt} on top of the input
10127 video, use the command:
10132 which is equivalent to:
10134 subtitles=filename=sub.srt
10137 To render the default subtitles stream from file @file{video.mkv}, use:
10139 subtitles=video.mkv
10142 To render the second subtitles stream from that file, use:
10144 subtitles=video.mkv:si=1
10147 To make the subtitles stream from @file{sub.srt} appear in transparent green
10148 @code{DejaVu Serif}, use:
10150 subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
10153 @section super2xsai
10155 Scale the input by 2x and smooth using the Super2xSaI (Scale and
10156 Interpolate) pixel art scaling algorithm.
10158 Useful for enlarging pixel art images without reducing sharpness.
10165 Apply telecine process to the video.
10167 This filter accepts the following options:
10176 The default value is @code{top}.
10180 A string of numbers representing the pulldown pattern you wish to apply.
10181 The default value is @code{23}.
10185 Some typical patterns:
10190 24p: 2332 (preferred)
10197 24p: 222222222223 ("Euro pulldown")
10203 Select the most representative frame in a given sequence of consecutive frames.
10205 The filter accepts the following options:
10209 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
10210 will pick one of them, and then handle the next batch of @var{n} frames until
10211 the end. Default is @code{100}.
10214 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
10215 value will result in a higher memory usage, so a high value is not recommended.
10217 @subsection Examples
10221 Extract one picture each 50 frames:
10227 Complete example of a thumbnail creation with @command{ffmpeg}:
10229 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
10235 Tile several successive frames together.
10237 The filter accepts the following options:
10242 Set the grid size (i.e. the number of lines and columns). For the syntax of
10243 this option, check the
10244 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10247 Set the maximum number of frames to render in the given area. It must be less
10248 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
10249 the area will be used.
10252 Set the outer border margin in pixels.
10255 Set the inner border thickness (i.e. the number of pixels between frames). For
10256 more advanced padding options (such as having different values for the edges),
10257 refer to the pad video filter.
10260 Specify the color of the unused area. For the syntax of this option, check the
10261 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
10265 @subsection Examples
10269 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
10271 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
10273 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
10274 duplicating each output frame to accommodate the originally detected frame
10278 Display @code{5} pictures in an area of @code{3x2} frames,
10279 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
10280 mixed flat and named options:
10282 tile=3x2:nb_frames=5:padding=7:margin=2
10286 @section tinterlace
10288 Perform various types of temporal field interlacing.
10290 Frames are counted starting from 1, so the first input frame is
10293 The filter accepts the following options:
10298 Specify the mode of the interlacing. This option can also be specified
10299 as a value alone. See below for a list of values for this option.
10301 Available values are:
10305 Move odd frames into the upper field, even into the lower field,
10306 generating a double height frame at half frame rate.
10310 Frame 1 Frame 2 Frame 3 Frame 4
10312 11111 22222 33333 44444
10313 11111 22222 33333 44444
10314 11111 22222 33333 44444
10315 11111 22222 33333 44444
10329 Only output even frames, odd frames are dropped, generating a frame with
10330 unchanged height at half frame rate.
10335 Frame 1 Frame 2 Frame 3 Frame 4
10337 11111 22222 33333 44444
10338 11111 22222 33333 44444
10339 11111 22222 33333 44444
10340 11111 22222 33333 44444
10350 Only output odd frames, even frames are dropped, generating a frame with
10351 unchanged height at half frame rate.
10356 Frame 1 Frame 2 Frame 3 Frame 4
10358 11111 22222 33333 44444
10359 11111 22222 33333 44444
10360 11111 22222 33333 44444
10361 11111 22222 33333 44444
10371 Expand each frame to full height, but pad alternate lines with black,
10372 generating a frame with double height at the same input frame rate.
10377 Frame 1 Frame 2 Frame 3 Frame 4
10379 11111 22222 33333 44444
10380 11111 22222 33333 44444
10381 11111 22222 33333 44444
10382 11111 22222 33333 44444
10385 11111 ..... 33333 .....
10386 ..... 22222 ..... 44444
10387 11111 ..... 33333 .....
10388 ..... 22222 ..... 44444
10389 11111 ..... 33333 .....
10390 ..... 22222 ..... 44444
10391 11111 ..... 33333 .....
10392 ..... 22222 ..... 44444
10396 @item interleave_top, 4
10397 Interleave the upper field from odd frames with the lower field from
10398 even frames, generating a frame with unchanged height at half frame rate.
10403 Frame 1 Frame 2 Frame 3 Frame 4
10405 11111<- 22222 33333<- 44444
10406 11111 22222<- 33333 44444<-
10407 11111<- 22222 33333<- 44444
10408 11111 22222<- 33333 44444<-
10418 @item interleave_bottom, 5
10419 Interleave the lower field from odd frames with the upper field from
10420 even frames, generating a frame with unchanged height at half frame rate.
10425 Frame 1 Frame 2 Frame 3 Frame 4
10427 11111 22222<- 33333 44444<-
10428 11111<- 22222 33333<- 44444
10429 11111 22222<- 33333 44444<-
10430 11111<- 22222 33333<- 44444
10440 @item interlacex2, 6
10441 Double frame rate with unchanged height. Frames are inserted each
10442 containing the second temporal field from the previous input frame and
10443 the first temporal field from the next input frame. This mode relies on
10444 the top_field_first flag. Useful for interlaced video displays with no
10445 field synchronisation.
10450 Frame 1 Frame 2 Frame 3 Frame 4
10452 11111 22222 33333 44444
10453 11111 22222 33333 44444
10454 11111 22222 33333 44444
10455 11111 22222 33333 44444
10458 11111 22222 22222 33333 33333 44444 44444
10459 11111 11111 22222 22222 33333 33333 44444
10460 11111 22222 22222 33333 33333 44444 44444
10461 11111 11111 22222 22222 33333 33333 44444
10467 Numeric values are deprecated but are accepted for backward
10468 compatibility reasons.
10470 Default mode is @code{merge}.
10473 Specify flags influencing the filter process.
10475 Available value for @var{flags} is:
10478 @item low_pass_filter, vlfp
10479 Enable vertical low-pass filtering in the filter.
10480 Vertical low-pass filtering is required when creating an interlaced
10481 destination from a progressive source which contains high-frequency
10482 vertical detail. Filtering will reduce interlace 'twitter' and Moire
10485 Vertical low-pass filtering can only be enabled for @option{mode}
10486 @var{interleave_top} and @var{interleave_bottom}.
10493 Transpose rows with columns in the input video and optionally flip it.
10495 It accepts the following parameters:
10500 Specify the transposition direction.
10502 Can assume the following values:
10504 @item 0, 4, cclock_flip
10505 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
10513 Rotate by 90 degrees clockwise, that is:
10521 Rotate by 90 degrees counterclockwise, that is:
10528 @item 3, 7, clock_flip
10529 Rotate by 90 degrees clockwise and vertically flip, that is:
10537 For values between 4-7, the transposition is only done if the input
10538 video geometry is portrait and not landscape. These values are
10539 deprecated, the @code{passthrough} option should be used instead.
10541 Numerical values are deprecated, and should be dropped in favor of
10542 symbolic constants.
10545 Do not apply the transposition if the input geometry matches the one
10546 specified by the specified value. It accepts the following values:
10549 Always apply transposition.
10551 Preserve portrait geometry (when @var{height} >= @var{width}).
10553 Preserve landscape geometry (when @var{width} >= @var{height}).
10556 Default value is @code{none}.
10559 For example to rotate by 90 degrees clockwise and preserve portrait
10562 transpose=dir=1:passthrough=portrait
10565 The command above can also be specified as:
10567 transpose=1:portrait
10571 Trim the input so that the output contains one continuous subpart of the input.
10573 It accepts the following parameters:
10576 Specify the time of the start of the kept section, i.e. the frame with the
10577 timestamp @var{start} will be the first frame in the output.
10580 Specify the time of the first frame that will be dropped, i.e. the frame
10581 immediately preceding the one with the timestamp @var{end} will be the last
10582 frame in the output.
10585 This is the same as @var{start}, except this option sets the start timestamp
10586 in timebase units instead of seconds.
10589 This is the same as @var{end}, except this option sets the end timestamp
10590 in timebase units instead of seconds.
10593 The maximum duration of the output in seconds.
10596 The number of the first frame that should be passed to the output.
10599 The number of the first frame that should be dropped.
10602 @option{start}, @option{end}, and @option{duration} are expressed as time
10603 duration specifications; see
10604 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
10605 for the accepted syntax.
10607 Note that the first two sets of the start/end options and the @option{duration}
10608 option look at the frame timestamp, while the _frame variants simply count the
10609 frames that pass through the filter. Also note that this filter does not modify
10610 the timestamps. If you wish for the output timestamps to start at zero, insert a
10611 setpts filter after the trim filter.
10613 If multiple start or end options are set, this filter tries to be greedy and
10614 keep all the frames that match at least one of the specified constraints. To keep
10615 only the part that matches all the constraints at once, chain multiple trim
10618 The defaults are such that all the input is kept. So it is possible to set e.g.
10619 just the end values to keep everything before the specified time.
10624 Drop everything except the second minute of input:
10626 ffmpeg -i INPUT -vf trim=60:120
10630 Keep only the first second:
10632 ffmpeg -i INPUT -vf trim=duration=1
10641 Sharpen or blur the input video.
10643 It accepts the following parameters:
10646 @item luma_msize_x, lx
10647 Set the luma matrix horizontal size. It must be an odd integer between
10648 3 and 63. The default value is 5.
10650 @item luma_msize_y, ly
10651 Set the luma matrix vertical size. It must be an odd integer between 3
10652 and 63. The default value is 5.
10654 @item luma_amount, la
10655 Set the luma effect strength. It must be a floating point number, reasonable
10656 values lay between -1.5 and 1.5.
10658 Negative values will blur the input video, while positive values will
10659 sharpen it, a value of zero will disable the effect.
10661 Default value is 1.0.
10663 @item chroma_msize_x, cx
10664 Set the chroma matrix horizontal size. It must be an odd integer
10665 between 3 and 63. The default value is 5.
10667 @item chroma_msize_y, cy
10668 Set the chroma matrix vertical size. It must be an odd integer
10669 between 3 and 63. The default value is 5.
10671 @item chroma_amount, ca
10672 Set the chroma effect strength. It must be a floating point number, reasonable
10673 values lay between -1.5 and 1.5.
10675 Negative values will blur the input video, while positive values will
10676 sharpen it, a value of zero will disable the effect.
10678 Default value is 0.0.
10681 If set to 1, specify using OpenCL capabilities, only available if
10682 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
10686 All parameters are optional and default to the equivalent of the
10687 string '5:5:1.0:5:5:0.0'.
10689 @subsection Examples
10693 Apply strong luma sharpen effect:
10695 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
10699 Apply a strong blur of both luma and chroma parameters:
10701 unsharp=7:7:-2:7:7:-2
10707 Apply ultra slow/simple postprocessing filter that compresses and decompresses
10708 the image at several (or - in the case of @option{quality} level @code{8} - all)
10709 shifts and average the results.
10711 The way this differs from the behavior of spp is that uspp actually encodes &
10712 decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
10713 DCT similar to MJPEG.
10715 The filter accepts the following options:
10719 Set quality. This option defines the number of levels for averaging. It accepts
10720 an integer in the range 0-8. If set to @code{0}, the filter will have no
10721 effect. A value of @code{8} means the higher quality. For each increment of
10722 that value the speed drops by a factor of approximately 2. Default value is
10726 Force a constant quantization parameter. If not set, the filter will use the QP
10727 from the video stream (if available).
10730 @section vectorscope
10732 Display 2 color component values in the two dimensional graph (which is called
10735 This filter accepts the following options:
10739 Set vectorscope mode.
10741 It accepts the following values:
10744 Gray values are displayed on graph, higher brightness means more pixels have
10745 same component color value on location in graph. This is the default mode.
10748 Gray values are displayed on graph. Surrounding pixels values which are not
10749 present in video frame are drawn in gradient of 2 color components which are
10750 set by option @code{x} and @code{y}.
10753 Actual color components values present in video frame are displayed on graph.
10756 Similar as color2 but higher frequency of same values @code{x} and @code{y}
10757 on graph increases value of another color component, which is luminance by
10758 default values of @code{x} and @code{y}.
10761 Actual colors present in video frame are displayed on graph. If two different
10762 colors map to same position on graph then color with higher value of component
10763 not present in graph is picked.
10767 Set which color component will be represented on X-axis. Default is @code{1}.
10770 Set which color component will be represented on Y-axis. Default is @code{2}.
10773 Set intensity, used by modes: gray, color and color3 for increasing brightness
10774 of color component which represents frequency of (X, Y) location in graph.
10779 No envelope, this is default.
10782 Instant envelope, even darkest single pixel will be clearly highlighted.
10785 Hold maximum and minimum values presented in graph over time. This way you
10786 can still spot out of range values without constantly looking at vectorscope.
10789 Peak and instant envelope combined together.
10793 @anchor{vidstabdetect}
10794 @section vidstabdetect
10796 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
10797 @ref{vidstabtransform} for pass 2.
10799 This filter generates a file with relative translation and rotation
10800 transform information about subsequent frames, which is then used by
10801 the @ref{vidstabtransform} filter.
10803 To enable compilation of this filter you need to configure FFmpeg with
10804 @code{--enable-libvidstab}.
10806 This filter accepts the following options:
10810 Set the path to the file used to write the transforms information.
10811 Default value is @file{transforms.trf}.
10814 Set how shaky the video is and how quick the camera is. It accepts an
10815 integer in the range 1-10, a value of 1 means little shakiness, a
10816 value of 10 means strong shakiness. Default value is 5.
10819 Set the accuracy of the detection process. It must be a value in the
10820 range 1-15. A value of 1 means low accuracy, a value of 15 means high
10821 accuracy. Default value is 15.
10824 Set stepsize of the search process. The region around minimum is
10825 scanned with 1 pixel resolution. Default value is 6.
10828 Set minimum contrast. Below this value a local measurement field is
10829 discarded. Must be a floating point value in the range 0-1. Default
10833 Set reference frame number for tripod mode.
10835 If enabled, the motion of the frames is compared to a reference frame
10836 in the filtered stream, identified by the specified number. The idea
10837 is to compensate all movements in a more-or-less static scene and keep
10838 the camera view absolutely still.
10840 If set to 0, it is disabled. The frames are counted starting from 1.
10843 Show fields and transforms in the resulting frames. It accepts an
10844 integer in the range 0-2. Default value is 0, which disables any
10848 @subsection Examples
10852 Use default values:
10858 Analyze strongly shaky movie and put the results in file
10859 @file{mytransforms.trf}:
10861 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
10865 Visualize the result of internal transformations in the resulting
10868 vidstabdetect=show=1
10872 Analyze a video with medium shakiness using @command{ffmpeg}:
10874 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
10878 @anchor{vidstabtransform}
10879 @section vidstabtransform
10881 Video stabilization/deshaking: pass 2 of 2,
10882 see @ref{vidstabdetect} for pass 1.
10884 Read a file with transform information for each frame and
10885 apply/compensate them. Together with the @ref{vidstabdetect}
10886 filter this can be used to deshake videos. See also
10887 @url{http://public.hronopik.de/vid.stab}. It is important to also use
10888 the @ref{unsharp} filter, see below.
10890 To enable compilation of this filter you need to configure FFmpeg with
10891 @code{--enable-libvidstab}.
10893 @subsection Options
10897 Set path to the file used to read the transforms. Default value is
10898 @file{transforms.trf}.
10901 Set the number of frames (value*2 + 1) used for lowpass filtering the
10902 camera movements. Default value is 10.
10904 For example a number of 10 means that 21 frames are used (10 in the
10905 past and 10 in the future) to smoothen the motion in the video. A
10906 larger value leads to a smoother video, but limits the acceleration of
10907 the camera (pan/tilt movements). 0 is a special case where a static
10908 camera is simulated.
10911 Set the camera path optimization algorithm.
10913 Accepted values are:
10916 gaussian kernel low-pass filter on camera motion (default)
10918 averaging on transformations
10922 Set maximal number of pixels to translate frames. Default value is -1,
10926 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
10927 value is -1, meaning no limit.
10930 Specify how to deal with borders that may be visible due to movement
10933 Available values are:
10936 keep image information from previous frame (default)
10938 fill the border black
10942 Invert transforms if set to 1. Default value is 0.
10945 Consider transforms as relative to previous frame if set to 1,
10946 absolute if set to 0. Default value is 0.
10949 Set percentage to zoom. A positive value will result in a zoom-in
10950 effect, a negative value in a zoom-out effect. Default value is 0 (no
10954 Set optimal zooming to avoid borders.
10956 Accepted values are:
10961 optimal static zoom value is determined (only very strong movements
10962 will lead to visible borders) (default)
10964 optimal adaptive zoom value is determined (no borders will be
10965 visible), see @option{zoomspeed}
10968 Note that the value given at zoom is added to the one calculated here.
10971 Set percent to zoom maximally each frame (enabled when
10972 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
10976 Specify type of interpolation.
10978 Available values are:
10983 linear only horizontal
10985 linear in both directions (default)
10987 cubic in both directions (slow)
10991 Enable virtual tripod mode if set to 1, which is equivalent to
10992 @code{relative=0:smoothing=0}. Default value is 0.
10994 Use also @code{tripod} option of @ref{vidstabdetect}.
10997 Increase log verbosity if set to 1. Also the detected global motions
10998 are written to the temporary file @file{global_motions.trf}. Default
11002 @subsection Examples
11006 Use @command{ffmpeg} for a typical stabilization with default values:
11008 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
11011 Note the use of the @ref{unsharp} filter which is always recommended.
11014 Zoom in a bit more and load transform data from a given file:
11016 vidstabtransform=zoom=5:input="mytransforms.trf"
11020 Smoothen the video even more:
11022 vidstabtransform=smoothing=30
11028 Flip the input video vertically.
11030 For example, to vertically flip a video with @command{ffmpeg}:
11032 ffmpeg -i in.avi -vf "vflip" out.avi
11038 Make or reverse a natural vignetting effect.
11040 The filter accepts the following options:
11044 Set lens angle expression as a number of radians.
11046 The value is clipped in the @code{[0,PI/2]} range.
11048 Default value: @code{"PI/5"}
11052 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
11056 Set forward/backward mode.
11058 Available modes are:
11061 The larger the distance from the central point, the darker the image becomes.
11064 The larger the distance from the central point, the brighter the image becomes.
11065 This can be used to reverse a vignette effect, though there is no automatic
11066 detection to extract the lens @option{angle} and other settings (yet). It can
11067 also be used to create a burning effect.
11070 Default value is @samp{forward}.
11073 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
11075 It accepts the following values:
11078 Evaluate expressions only once during the filter initialization.
11081 Evaluate expressions for each incoming frame. This is way slower than the
11082 @samp{init} mode since it requires all the scalers to be re-computed, but it
11083 allows advanced dynamic expressions.
11086 Default value is @samp{init}.
11089 Set dithering to reduce the circular banding effects. Default is @code{1}
11093 Set vignette aspect. This setting allows one to adjust the shape of the vignette.
11094 Setting this value to the SAR of the input will make a rectangular vignetting
11095 following the dimensions of the video.
11097 Default is @code{1/1}.
11100 @subsection Expressions
11102 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
11103 following parameters.
11108 input width and height
11111 the number of input frame, starting from 0
11114 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
11115 @var{TB} units, NAN if undefined
11118 frame rate of the input video, NAN if the input frame rate is unknown
11121 the PTS (Presentation TimeStamp) of the filtered video frame,
11122 expressed in seconds, NAN if undefined
11125 time base of the input video
11129 @subsection Examples
11133 Apply simple strong vignetting effect:
11139 Make a flickering vignetting:
11141 vignette='PI/4+random(1)*PI/50':eval=frame
11147 Stack input videos vertically.
11149 All streams must be of same pixel format and of same width.
11151 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
11152 to create same output.
11154 The filter accept the following option:
11158 Set number of input streams. Default is 2.
11163 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
11164 Deinterlacing Filter").
11166 Based on the process described by Martin Weston for BBC R&D, and
11167 implemented based on the de-interlace algorithm written by Jim
11168 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
11169 uses filter coefficients calculated by BBC R&D.
11171 There are two sets of filter coefficients, so called "simple":
11172 and "complex". Which set of filter coefficients is used can
11173 be set by passing an optional parameter:
11177 Set the interlacing filter coefficients. Accepts one of the following values:
11181 Simple filter coefficient set.
11183 More-complex filter coefficient set.
11185 Default value is @samp{complex}.
11188 Specify which frames to deinterlace. Accept one of the following values:
11192 Deinterlace all frames,
11194 Only deinterlace frames marked as interlaced.
11197 Default value is @samp{all}.
11201 Video waveform monitor.
11203 The waveform monitor plots color component intensity. By default luminance
11204 only. Each column of the waveform corresponds to a column of pixels in the
11207 It accepts the following options:
11211 Can be either @code{row}, or @code{column}. Default is @code{column}.
11212 In row mode, the graph on the left side represents color component value 0 and
11213 the right side represents value = 255. In column mode, the top side represents
11214 color component value = 0 and bottom side represents value = 255.
11217 Set intensity. Smaller values are useful to find out how many values of the same
11218 luminance are distributed across input rows/columns.
11219 Default value is @code{0.04}. Allowed range is [0, 1].
11222 Set mirroring mode. @code{0} means unmirrored, @code{1} means mirrored.
11223 In mirrored mode, higher values will be represented on the left
11224 side for @code{row} mode and at the top for @code{column} mode. Default is
11225 @code{1} (mirrored).
11229 It accepts the following values:
11232 Presents information identical to that in the @code{parade}, except
11233 that the graphs representing color components are superimposed directly
11236 This display mode makes it easier to spot relative differences or similarities
11237 in overlapping areas of the color components that are supposed to be identical,
11238 such as neutral whites, grays, or blacks.
11241 Display separate graph for the color components side by side in
11242 @code{row} mode or one below the other in @code{column} mode.
11244 Using this display mode makes it easy to spot color casts in the highlights
11245 and shadows of an image, by comparing the contours of the top and the bottom
11246 graphs of each waveform. Since whites, grays, and blacks are characterized
11247 by exactly equal amounts of red, green, and blue, neutral areas of the picture
11248 should display three waveforms of roughly equal width/height. If not, the
11249 correction is easy to perform by making level adjustments the three waveforms.
11251 Default is @code{parade}.
11253 @item components, c
11254 Set which color components to display. Default is 1, which means only luminance
11255 or red color component if input is in RGB colorspace. If is set for example to
11256 7 it will display all 3 (if) available color components.
11261 No envelope, this is default.
11264 Instant envelope, minimum and maximum values presented in graph will be easily
11265 visible even with small @code{step} value.
11268 Hold minimum and maximum values presented in graph across time. This way you
11269 can still spot out of range values without constantly looking at waveforms.
11272 Peak and instant envelope combined together.
11278 No filtering, this is default.
11281 Luma and chroma combined together.
11284 Similar as above, but shows difference between blue and red chroma.
11287 Displays only chroma.
11290 Similar as above, but shows difference between blue and red chroma.
11293 Displays actual color value on waveform.
11298 Apply the xBR high-quality magnification filter which is designed for pixel
11299 art. It follows a set of edge-detection rules, see
11300 @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}.
11302 It accepts the following option:
11306 Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
11307 @code{3xBR} and @code{4} for @code{4xBR}.
11308 Default is @code{3}.
11314 Deinterlace the input video ("yadif" means "yet another deinterlacing
11317 It accepts the following parameters:
11323 The interlacing mode to adopt. It accepts one of the following values:
11326 @item 0, send_frame
11327 Output one frame for each frame.
11328 @item 1, send_field
11329 Output one frame for each field.
11330 @item 2, send_frame_nospatial
11331 Like @code{send_frame}, but it skips the spatial interlacing check.
11332 @item 3, send_field_nospatial
11333 Like @code{send_field}, but it skips the spatial interlacing check.
11336 The default value is @code{send_frame}.
11339 The picture field parity assumed for the input interlaced video. It accepts one
11340 of the following values:
11344 Assume the top field is first.
11346 Assume the bottom field is first.
11348 Enable automatic detection of field parity.
11351 The default value is @code{auto}.
11352 If the interlacing is unknown or the decoder does not export this information,
11353 top field first will be assumed.
11356 Specify which frames to deinterlace. Accept one of the following
11361 Deinterlace all frames.
11362 @item 1, interlaced
11363 Only deinterlace frames marked as interlaced.
11366 The default value is @code{all}.
11371 Apply Zoom & Pan effect.
11373 This filter accepts the following options:
11377 Set the zoom expression. Default is 1.
11381 Set the x and y expression. Default is 0.
11384 Set the duration expression in number of frames.
11385 This sets for how many number of frames effect will last for
11386 single input image.
11389 Set the output image size, default is 'hd720'.
11392 Each expression can contain the following constants:
11411 Output frame count.
11415 Last calculated 'x' and 'y' position from 'x' and 'y' expression
11416 for current input frame.
11420 'x' and 'y' of last output frame of previous input frame or 0 when there was
11421 not yet such frame (first input frame).
11424 Last calculated zoom from 'z' expression for current input frame.
11427 Last calculated zoom of last output frame of previous input frame.
11430 Number of output frames for current input frame. Calculated from 'd' expression
11431 for each input frame.
11434 number of output frames created for previous input frame
11437 Rational number: input width / input height
11440 sample aspect ratio
11443 display aspect ratio
11447 @subsection Examples
11451 Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
11453 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360
11457 Zoom-in up to 1.5 and pan always at center of picture:
11459 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
11463 @c man end VIDEO FILTERS
11465 @chapter Video Sources
11466 @c man begin VIDEO SOURCES
11468 Below is a description of the currently available video sources.
11472 Buffer video frames, and make them available to the filter chain.
11474 This source is mainly intended for a programmatic use, in particular
11475 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
11477 It accepts the following parameters:
11482 Specify the size (width and height) of the buffered video frames. For the
11483 syntax of this option, check the
11484 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11487 The input video width.
11490 The input video height.
11493 A string representing the pixel format of the buffered video frames.
11494 It may be a number corresponding to a pixel format, or a pixel format
11498 Specify the timebase assumed by the timestamps of the buffered frames.
11501 Specify the frame rate expected for the video stream.
11503 @item pixel_aspect, sar
11504 The sample (pixel) aspect ratio of the input video.
11507 Specify the optional parameters to be used for the scale filter which
11508 is automatically inserted when an input change is detected in the
11509 input size or format.
11514 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
11517 will instruct the source to accept video frames with size 320x240 and
11518 with format "yuv410p", assuming 1/24 as the timestamps timebase and
11519 square pixels (1:1 sample aspect ratio).
11520 Since the pixel format with name "yuv410p" corresponds to the number 6
11521 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
11522 this example corresponds to:
11524 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
11527 Alternatively, the options can be specified as a flat string, but this
11528 syntax is deprecated:
11530 @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}]
11534 Create a pattern generated by an elementary cellular automaton.
11536 The initial state of the cellular automaton can be defined through the
11537 @option{filename}, and @option{pattern} options. If such options are
11538 not specified an initial state is created randomly.
11540 At each new frame a new row in the video is filled with the result of
11541 the cellular automaton next generation. The behavior when the whole
11542 frame is filled is defined by the @option{scroll} option.
11544 This source accepts the following options:
11548 Read the initial cellular automaton state, i.e. the starting row, from
11549 the specified file.
11550 In the file, each non-whitespace character is considered an alive
11551 cell, a newline will terminate the row, and further characters in the
11552 file will be ignored.
11555 Read the initial cellular automaton state, i.e. the starting row, from
11556 the specified string.
11558 Each non-whitespace character in the string is considered an alive
11559 cell, a newline will terminate the row, and further characters in the
11560 string will be ignored.
11563 Set the video rate, that is the number of frames generated per second.
11566 @item random_fill_ratio, ratio
11567 Set the random fill ratio for the initial cellular automaton row. It
11568 is a floating point number value ranging from 0 to 1, defaults to
11571 This option is ignored when a file or a pattern is specified.
11573 @item random_seed, seed
11574 Set the seed for filling randomly the initial row, must be an integer
11575 included between 0 and UINT32_MAX. If not specified, or if explicitly
11576 set to -1, the filter will try to use a good random seed on a best
11580 Set the cellular automaton rule, it is a number ranging from 0 to 255.
11581 Default value is 110.
11584 Set the size of the output video. For the syntax of this option, check the
11585 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11587 If @option{filename} or @option{pattern} is specified, the size is set
11588 by default to the width of the specified initial state row, and the
11589 height is set to @var{width} * PHI.
11591 If @option{size} is set, it must contain the width of the specified
11592 pattern string, and the specified pattern will be centered in the
11595 If a filename or a pattern string is not specified, the size value
11596 defaults to "320x518" (used for a randomly generated initial state).
11599 If set to 1, scroll the output upward when all the rows in the output
11600 have been already filled. If set to 0, the new generated row will be
11601 written over the top row just after the bottom row is filled.
11604 @item start_full, full
11605 If set to 1, completely fill the output with generated rows before
11606 outputting the first frame.
11607 This is the default behavior, for disabling set the value to 0.
11610 If set to 1, stitch the left and right row edges together.
11611 This is the default behavior, for disabling set the value to 0.
11614 @subsection Examples
11618 Read the initial state from @file{pattern}, and specify an output of
11621 cellauto=f=pattern:s=200x400
11625 Generate a random initial row with a width of 200 cells, with a fill
11628 cellauto=ratio=2/3:s=200x200
11632 Create a pattern generated by rule 18 starting by a single alive cell
11633 centered on an initial row with width 100:
11635 cellauto=p=@@:s=100x400:full=0:rule=18
11639 Specify a more elaborated initial pattern:
11641 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
11646 @section mandelbrot
11648 Generate a Mandelbrot set fractal, and progressively zoom towards the
11649 point specified with @var{start_x} and @var{start_y}.
11651 This source accepts the following options:
11656 Set the terminal pts value. Default value is 400.
11659 Set the terminal scale value.
11660 Must be a floating point value. Default value is 0.3.
11663 Set the inner coloring mode, that is the algorithm used to draw the
11664 Mandelbrot fractal internal region.
11666 It shall assume one of the following values:
11671 Show time until convergence.
11673 Set color based on point closest to the origin of the iterations.
11678 Default value is @var{mincol}.
11681 Set the bailout value. Default value is 10.0.
11684 Set the maximum of iterations performed by the rendering
11685 algorithm. Default value is 7189.
11688 Set outer coloring mode.
11689 It shall assume one of following values:
11691 @item iteration_count
11692 Set iteration cound mode.
11693 @item normalized_iteration_count
11694 set normalized iteration count mode.
11696 Default value is @var{normalized_iteration_count}.
11699 Set frame rate, expressed as number of frames per second. Default
11703 Set frame size. For the syntax of this option, check the "Video
11704 size" section in the ffmpeg-utils manual. Default value is "640x480".
11707 Set the initial scale value. Default value is 3.0.
11710 Set the initial x position. Must be a floating point value between
11711 -100 and 100. Default value is -0.743643887037158704752191506114774.
11714 Set the initial y position. Must be a floating point value between
11715 -100 and 100. Default value is -0.131825904205311970493132056385139.
11720 Generate various test patterns, as generated by the MPlayer test filter.
11722 The size of the generated video is fixed, and is 256x256.
11723 This source is useful in particular for testing encoding features.
11725 This source accepts the following options:
11730 Specify the frame rate of the sourced video, as the number of frames
11731 generated per second. It has to be a string in the format
11732 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
11733 number or a valid video frame rate abbreviation. The default value is
11737 Set the duration of the sourced video. See
11738 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
11739 for the accepted syntax.
11741 If not specified, or the expressed duration is negative, the video is
11742 supposed to be generated forever.
11746 Set the number or the name of the test to perform. Supported tests are:
11762 Default value is "all", which will cycle through the list of all tests.
11767 mptestsrc=t=dc_luma
11770 will generate a "dc_luma" test pattern.
11772 @section frei0r_src
11774 Provide a frei0r source.
11776 To enable compilation of this filter you need to install the frei0r
11777 header and configure FFmpeg with @code{--enable-frei0r}.
11779 This source accepts the following parameters:
11784 The size of the video to generate. For the syntax of this option, check the
11785 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11788 The framerate of the generated video. It may be a string of the form
11789 @var{num}/@var{den} or a frame rate abbreviation.
11792 The name to the frei0r source to load. For more information regarding frei0r and
11793 how to set the parameters, read the @ref{frei0r} section in the video filters
11796 @item filter_params
11797 A '|'-separated list of parameters to pass to the frei0r source.
11801 For example, to generate a frei0r partik0l source with size 200x200
11802 and frame rate 10 which is overlaid on the overlay filter main input:
11804 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
11809 Generate a life pattern.
11811 This source is based on a generalization of John Conway's life game.
11813 The sourced input represents a life grid, each pixel represents a cell
11814 which can be in one of two possible states, alive or dead. Every cell
11815 interacts with its eight neighbours, which are the cells that are
11816 horizontally, vertically, or diagonally adjacent.
11818 At each interaction the grid evolves according to the adopted rule,
11819 which specifies the number of neighbor alive cells which will make a
11820 cell stay alive or born. The @option{rule} option allows one to specify
11823 This source accepts the following options:
11827 Set the file from which to read the initial grid state. In the file,
11828 each non-whitespace character is considered an alive cell, and newline
11829 is used to delimit the end of each row.
11831 If this option is not specified, the initial grid is generated
11835 Set the video rate, that is the number of frames generated per second.
11838 @item random_fill_ratio, ratio
11839 Set the random fill ratio for the initial random grid. It is a
11840 floating point number value ranging from 0 to 1, defaults to 1/PHI.
11841 It is ignored when a file is specified.
11843 @item random_seed, seed
11844 Set the seed for filling the initial random grid, must be an integer
11845 included between 0 and UINT32_MAX. If not specified, or if explicitly
11846 set to -1, the filter will try to use a good random seed on a best
11852 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
11853 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
11854 @var{NS} specifies the number of alive neighbor cells which make a
11855 live cell stay alive, and @var{NB} the number of alive neighbor cells
11856 which make a dead cell to become alive (i.e. to "born").
11857 "s" and "b" can be used in place of "S" and "B", respectively.
11859 Alternatively a rule can be specified by an 18-bits integer. The 9
11860 high order bits are used to encode the next cell state if it is alive
11861 for each number of neighbor alive cells, the low order bits specify
11862 the rule for "borning" new cells. Higher order bits encode for an
11863 higher number of neighbor cells.
11864 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
11865 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
11867 Default value is "S23/B3", which is the original Conway's game of life
11868 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
11869 cells, and will born a new cell if there are three alive cells around
11873 Set the size of the output video. For the syntax of this option, check the
11874 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11876 If @option{filename} is specified, the size is set by default to the
11877 same size of the input file. If @option{size} is set, it must contain
11878 the size specified in the input file, and the initial grid defined in
11879 that file is centered in the larger resulting area.
11881 If a filename is not specified, the size value defaults to "320x240"
11882 (used for a randomly generated initial grid).
11885 If set to 1, stitch the left and right grid edges together, and the
11886 top and bottom edges also. Defaults to 1.
11889 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
11890 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
11891 value from 0 to 255.
11894 Set the color of living (or new born) cells.
11897 Set the color of dead cells. If @option{mold} is set, this is the first color
11898 used to represent a dead cell.
11901 Set mold color, for definitely dead and moldy cells.
11903 For the syntax of these 3 color options, check the "Color" section in the
11904 ffmpeg-utils manual.
11907 @subsection Examples
11911 Read a grid from @file{pattern}, and center it on a grid of size
11914 life=f=pattern:s=300x300
11918 Generate a random grid of size 200x200, with a fill ratio of 2/3:
11920 life=ratio=2/3:s=200x200
11924 Specify a custom rule for evolving a randomly generated grid:
11930 Full example with slow death effect (mold) using @command{ffplay}:
11932 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
11939 @anchor{haldclutsrc}
11941 @anchor{rgbtestsrc}
11943 @anchor{smptehdbars}
11945 @section allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
11947 The @code{allrgb} source returns frames of size 4096x4096 of all rgb colors.
11949 The @code{allyuv} source returns frames of size 4096x4096 of all yuv colors.
11951 The @code{color} source provides an uniformly colored input.
11953 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
11954 @ref{haldclut} filter.
11956 The @code{nullsrc} source returns unprocessed video frames. It is
11957 mainly useful to be employed in analysis / debugging tools, or as the
11958 source for filters which ignore the input data.
11960 The @code{rgbtestsrc} source generates an RGB test pattern useful for
11961 detecting RGB vs BGR issues. You should see a red, green and blue
11962 stripe from top to bottom.
11964 The @code{smptebars} source generates a color bars pattern, based on
11965 the SMPTE Engineering Guideline EG 1-1990.
11967 The @code{smptehdbars} source generates a color bars pattern, based on
11968 the SMPTE RP 219-2002.
11970 The @code{testsrc} source generates a test video pattern, showing a
11971 color pattern, a scrolling gradient and a timestamp. This is mainly
11972 intended for testing purposes.
11974 The sources accept the following parameters:
11979 Specify the color of the source, only available in the @code{color}
11980 source. For the syntax of this option, check the "Color" section in the
11981 ffmpeg-utils manual.
11984 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
11985 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
11986 pixels to be used as identity matrix for 3D lookup tables. Each component is
11987 coded on a @code{1/(N*N)} scale.
11990 Specify the size of the sourced video. For the syntax of this option, check the
11991 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11992 The default value is @code{320x240}.
11994 This option is not available with the @code{haldclutsrc} filter.
11997 Specify the frame rate of the sourced video, as the number of frames
11998 generated per second. It has to be a string in the format
11999 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
12000 number or a valid video frame rate abbreviation. The default value is
12004 Set the sample aspect ratio of the sourced video.
12007 Set the duration of the sourced video. See
12008 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12009 for the accepted syntax.
12011 If not specified, or the expressed duration is negative, the video is
12012 supposed to be generated forever.
12015 Set the number of decimals to show in the timestamp, only available in the
12016 @code{testsrc} source.
12018 The displayed timestamp value will correspond to the original
12019 timestamp value multiplied by the power of 10 of the specified
12020 value. Default value is 0.
12023 For example the following:
12025 testsrc=duration=5.3:size=qcif:rate=10
12028 will generate a video with a duration of 5.3 seconds, with size
12029 176x144 and a frame rate of 10 frames per second.
12031 The following graph description will generate a red source
12032 with an opacity of 0.2, with size "qcif" and a frame rate of 10
12035 color=c=red@@0.2:s=qcif:r=10
12038 If the input content is to be ignored, @code{nullsrc} can be used. The
12039 following command generates noise in the luminance plane by employing
12040 the @code{geq} filter:
12042 nullsrc=s=256x256, geq=random(1)*255:128:128
12045 @subsection Commands
12047 The @code{color} source supports the following commands:
12051 Set the color of the created image. Accepts the same syntax of the
12052 corresponding @option{color} option.
12055 @c man end VIDEO SOURCES
12057 @chapter Video Sinks
12058 @c man begin VIDEO SINKS
12060 Below is a description of the currently available video sinks.
12062 @section buffersink
12064 Buffer video frames, and make them available to the end of the filter
12067 This sink is mainly intended for programmatic use, in particular
12068 through the interface defined in @file{libavfilter/buffersink.h}
12069 or the options system.
12071 It accepts a pointer to an AVBufferSinkContext structure, which
12072 defines the incoming buffers' formats, to be passed as the opaque
12073 parameter to @code{avfilter_init_filter} for initialization.
12077 Null video sink: do absolutely nothing with the input video. It is
12078 mainly useful as a template and for use in analysis / debugging
12081 @c man end VIDEO SINKS
12083 @chapter Multimedia Filters
12084 @c man begin MULTIMEDIA FILTERS
12086 Below is a description of the currently available multimedia filters.
12088 @section aphasemeter
12090 Convert input audio to a video output, displaying the audio phase.
12092 The filter accepts the following options:
12096 Set the output frame rate. Default value is @code{25}.
12099 Set the video size for the output. For the syntax of this option, check the
12100 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12101 Default value is @code{800x400}.
12106 Specify the red, green, blue contrast. Default values are @code{2},
12107 @code{7} and @code{1}.
12108 Allowed range is @code{[0, 255]}.
12111 Set color which will be used for drawing median phase. If color is
12112 @code{none} which is default, no median phase value will be drawn.
12115 The filter also exports the frame metadata @code{lavfi.aphasemeter.phase} which
12116 represents mean phase of current audio frame. Value is in range @code{[-1, 1]}.
12117 The @code{-1} means left and right channels are completely out of phase and
12118 @code{1} means channels are in phase.
12120 @section avectorscope
12122 Convert input audio to a video output, representing the audio vector
12125 The filter is used to measure the difference between channels of stereo
12126 audio stream. A monoaural signal, consisting of identical left and right
12127 signal, results in straight vertical line. Any stereo separation is visible
12128 as a deviation from this line, creating a Lissajous figure.
12129 If the straight (or deviation from it) but horizontal line appears this
12130 indicates that the left and right channels are out of phase.
12132 The filter accepts the following options:
12136 Set the vectorscope mode.
12138 Available values are:
12141 Lissajous rotated by 45 degrees.
12144 Same as above but not rotated.
12147 Shape resembling half of circle.
12150 Default value is @samp{lissajous}.
12153 Set the video size for the output. For the syntax of this option, check the
12154 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12155 Default value is @code{400x400}.
12158 Set the output frame rate. Default value is @code{25}.
12164 Specify the red, green, blue and alpha contrast. Default values are @code{40},
12165 @code{160}, @code{80} and @code{255}.
12166 Allowed range is @code{[0, 255]}.
12172 Specify the red, green, blue and alpha fade. Default values are @code{15},
12173 @code{10}, @code{5} and @code{5}.
12174 Allowed range is @code{[0, 255]}.
12177 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
12180 @subsection Examples
12184 Complete example using @command{ffplay}:
12186 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
12187 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
12193 Concatenate audio and video streams, joining them together one after the
12196 The filter works on segments of synchronized video and audio streams. All
12197 segments must have the same number of streams of each type, and that will
12198 also be the number of streams at output.
12200 The filter accepts the following options:
12205 Set the number of segments. Default is 2.
12208 Set the number of output video streams, that is also the number of video
12209 streams in each segment. Default is 1.
12212 Set the number of output audio streams, that is also the number of audio
12213 streams in each segment. Default is 0.
12216 Activate unsafe mode: do not fail if segments have a different format.
12220 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
12221 @var{a} audio outputs.
12223 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
12224 segment, in the same order as the outputs, then the inputs for the second
12227 Related streams do not always have exactly the same duration, for various
12228 reasons including codec frame size or sloppy authoring. For that reason,
12229 related synchronized streams (e.g. a video and its audio track) should be
12230 concatenated at once. The concat filter will use the duration of the longest
12231 stream in each segment (except the last one), and if necessary pad shorter
12232 audio streams with silence.
12234 For this filter to work correctly, all segments must start at timestamp 0.
12236 All corresponding streams must have the same parameters in all segments; the
12237 filtering system will automatically select a common pixel format for video
12238 streams, and a common sample format, sample rate and channel layout for
12239 audio streams, but other settings, such as resolution, must be converted
12240 explicitly by the user.
12242 Different frame rates are acceptable but will result in variable frame rate
12243 at output; be sure to configure the output file to handle it.
12245 @subsection Examples
12249 Concatenate an opening, an episode and an ending, all in bilingual version
12250 (video in stream 0, audio in streams 1 and 2):
12252 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
12253 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
12254 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
12255 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
12259 Concatenate two parts, handling audio and video separately, using the
12260 (a)movie sources, and adjusting the resolution:
12262 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
12263 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
12264 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
12266 Note that a desync will happen at the stitch if the audio and video streams
12267 do not have exactly the same duration in the first file.
12274 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
12275 it unchanged. By default, it logs a message at a frequency of 10Hz with the
12276 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
12277 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
12279 The filter also has a video output (see the @var{video} option) with a real
12280 time graph to observe the loudness evolution. The graphic contains the logged
12281 message mentioned above, so it is not printed anymore when this option is set,
12282 unless the verbose logging is set. The main graphing area contains the
12283 short-term loudness (3 seconds of analysis), and the gauge on the right is for
12284 the momentary loudness (400 milliseconds).
12286 More information about the Loudness Recommendation EBU R128 on
12287 @url{http://tech.ebu.ch/loudness}.
12289 The filter accepts the following options:
12294 Activate the video output. The audio stream is passed unchanged whether this
12295 option is set or no. The video stream will be the first output stream if
12296 activated. Default is @code{0}.
12299 Set the video size. This option is for video only. For the syntax of this
12301 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12302 Default and minimum resolution is @code{640x480}.
12305 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
12306 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
12307 other integer value between this range is allowed.
12310 Set metadata injection. If set to @code{1}, the audio input will be segmented
12311 into 100ms output frames, each of them containing various loudness information
12312 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
12314 Default is @code{0}.
12317 Force the frame logging level.
12319 Available values are:
12322 information logging level
12324 verbose logging level
12327 By default, the logging level is set to @var{info}. If the @option{video} or
12328 the @option{metadata} options are set, it switches to @var{verbose}.
12333 Available modes can be cumulated (the option is a @code{flag} type). Possible
12337 Disable any peak mode (default).
12339 Enable sample-peak mode.
12341 Simple peak mode looking for the higher sample value. It logs a message
12342 for sample-peak (identified by @code{SPK}).
12344 Enable true-peak mode.
12346 If enabled, the peak lookup is done on an over-sampled version of the input
12347 stream for better peak accuracy. It logs a message for true-peak.
12348 (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}).
12349 This mode requires a build with @code{libswresample}.
12354 @subsection Examples
12358 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
12360 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
12364 Run an analysis with @command{ffmpeg}:
12366 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
12370 @section interleave, ainterleave
12372 Temporally interleave frames from several inputs.
12374 @code{interleave} works with video inputs, @code{ainterleave} with audio.
12376 These filters read frames from several inputs and send the oldest
12377 queued frame to the output.
12379 Input streams must have a well defined, monotonically increasing frame
12382 In order to submit one frame to output, these filters need to enqueue
12383 at least one frame for each input, so they cannot work in case one
12384 input is not yet terminated and will not receive incoming frames.
12386 For example consider the case when one input is a @code{select} filter
12387 which always drop input frames. The @code{interleave} filter will keep
12388 reading from that input, but it will never be able to send new frames
12389 to output until the input will send an end-of-stream signal.
12391 Also, depending on inputs synchronization, the filters will drop
12392 frames in case one input receives more frames than the other ones, and
12393 the queue is already filled.
12395 These filters accept the following options:
12399 Set the number of different inputs, it is 2 by default.
12402 @subsection Examples
12406 Interleave frames belonging to different streams using @command{ffmpeg}:
12408 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
12412 Add flickering blur effect:
12414 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
12418 @section perms, aperms
12420 Set read/write permissions for the output frames.
12422 These filters are mainly aimed at developers to test direct path in the
12423 following filter in the filtergraph.
12425 The filters accept the following options:
12429 Select the permissions mode.
12431 It accepts the following values:
12434 Do nothing. This is the default.
12436 Set all the output frames read-only.
12438 Set all the output frames directly writable.
12440 Make the frame read-only if writable, and writable if read-only.
12442 Set each output frame read-only or writable randomly.
12446 Set the seed for the @var{random} mode, must be an integer included between
12447 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
12448 @code{-1}, the filter will try to use a good random seed on a best effort
12452 Note: in case of auto-inserted filter between the permission filter and the
12453 following one, the permission might not be received as expected in that
12454 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
12455 perms/aperms filter can avoid this problem.
12457 @section select, aselect
12459 Select frames to pass in output.
12461 This filter accepts the following options:
12466 Set expression, which is evaluated for each input frame.
12468 If the expression is evaluated to zero, the frame is discarded.
12470 If the evaluation result is negative or NaN, the frame is sent to the
12471 first output; otherwise it is sent to the output with index
12472 @code{ceil(val)-1}, assuming that the input index starts from 0.
12474 For example a value of @code{1.2} corresponds to the output with index
12475 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
12478 Set the number of outputs. The output to which to send the selected
12479 frame is based on the result of the evaluation. Default value is 1.
12482 The expression can contain the following constants:
12486 The (sequential) number of the filtered frame, starting from 0.
12489 The (sequential) number of the selected frame, starting from 0.
12491 @item prev_selected_n
12492 The sequential number of the last selected frame. It's NAN if undefined.
12495 The timebase of the input timestamps.
12498 The PTS (Presentation TimeStamp) of the filtered video frame,
12499 expressed in @var{TB} units. It's NAN if undefined.
12502 The PTS of the filtered video frame,
12503 expressed in seconds. It's NAN if undefined.
12506 The PTS of the previously filtered video frame. It's NAN if undefined.
12508 @item prev_selected_pts
12509 The PTS of the last previously filtered video frame. It's NAN if undefined.
12511 @item prev_selected_t
12512 The PTS of the last previously selected video frame. It's NAN if undefined.
12515 The PTS of the first video frame in the video. It's NAN if undefined.
12518 The time of the first video frame in the video. It's NAN if undefined.
12520 @item pict_type @emph{(video only)}
12521 The type of the filtered frame. It can assume one of the following
12533 @item interlace_type @emph{(video only)}
12534 The frame interlace type. It can assume one of the following values:
12537 The frame is progressive (not interlaced).
12539 The frame is top-field-first.
12541 The frame is bottom-field-first.
12544 @item consumed_sample_n @emph{(audio only)}
12545 the number of selected samples before the current frame
12547 @item samples_n @emph{(audio only)}
12548 the number of samples in the current frame
12550 @item sample_rate @emph{(audio only)}
12551 the input sample rate
12554 This is 1 if the filtered frame is a key-frame, 0 otherwise.
12557 the position in the file of the filtered frame, -1 if the information
12558 is not available (e.g. for synthetic video)
12560 @item scene @emph{(video only)}
12561 value between 0 and 1 to indicate a new scene; a low value reflects a low
12562 probability for the current frame to introduce a new scene, while a higher
12563 value means the current frame is more likely to be one (see the example below)
12567 The default value of the select expression is "1".
12569 @subsection Examples
12573 Select all frames in input:
12578 The example above is the same as:
12590 Select only I-frames:
12592 select='eq(pict_type\,I)'
12596 Select one frame every 100:
12598 select='not(mod(n\,100))'
12602 Select only frames contained in the 10-20 time interval:
12604 select=between(t\,10\,20)
12608 Select only I frames contained in the 10-20 time interval:
12610 select=between(t\,10\,20)*eq(pict_type\,I)
12614 Select frames with a minimum distance of 10 seconds:
12616 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
12620 Use aselect to select only audio frames with samples number > 100:
12622 aselect='gt(samples_n\,100)'
12626 Create a mosaic of the first scenes:
12628 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
12631 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
12635 Send even and odd frames to separate outputs, and compose them:
12637 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
12641 @section sendcmd, asendcmd
12643 Send commands to filters in the filtergraph.
12645 These filters read commands to be sent to other filters in the
12648 @code{sendcmd} must be inserted between two video filters,
12649 @code{asendcmd} must be inserted between two audio filters, but apart
12650 from that they act the same way.
12652 The specification of commands can be provided in the filter arguments
12653 with the @var{commands} option, or in a file specified by the
12654 @var{filename} option.
12656 These filters accept the following options:
12659 Set the commands to be read and sent to the other filters.
12661 Set the filename of the commands to be read and sent to the other
12665 @subsection Commands syntax
12667 A commands description consists of a sequence of interval
12668 specifications, comprising a list of commands to be executed when a
12669 particular event related to that interval occurs. The occurring event
12670 is typically the current frame time entering or leaving a given time
12673 An interval is specified by the following syntax:
12675 @var{START}[-@var{END}] @var{COMMANDS};
12678 The time interval is specified by the @var{START} and @var{END} times.
12679 @var{END} is optional and defaults to the maximum time.
12681 The current frame time is considered within the specified interval if
12682 it is included in the interval [@var{START}, @var{END}), that is when
12683 the time is greater or equal to @var{START} and is lesser than
12686 @var{COMMANDS} consists of a sequence of one or more command
12687 specifications, separated by ",", relating to that interval. The
12688 syntax of a command specification is given by:
12690 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
12693 @var{FLAGS} is optional and specifies the type of events relating to
12694 the time interval which enable sending the specified command, and must
12695 be a non-null sequence of identifier flags separated by "+" or "|" and
12696 enclosed between "[" and "]".
12698 The following flags are recognized:
12701 The command is sent when the current frame timestamp enters the
12702 specified interval. In other words, the command is sent when the
12703 previous frame timestamp was not in the given interval, and the
12707 The command is sent when the current frame timestamp leaves the
12708 specified interval. In other words, the command is sent when the
12709 previous frame timestamp was in the given interval, and the
12713 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
12716 @var{TARGET} specifies the target of the command, usually the name of
12717 the filter class or a specific filter instance name.
12719 @var{COMMAND} specifies the name of the command for the target filter.
12721 @var{ARG} is optional and specifies the optional list of argument for
12722 the given @var{COMMAND}.
12724 Between one interval specification and another, whitespaces, or
12725 sequences of characters starting with @code{#} until the end of line,
12726 are ignored and can be used to annotate comments.
12728 A simplified BNF description of the commands specification syntax
12731 @var{COMMAND_FLAG} ::= "enter" | "leave"
12732 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
12733 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
12734 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
12735 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
12736 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
12739 @subsection Examples
12743 Specify audio tempo change at second 4:
12745 asendcmd=c='4.0 atempo tempo 1.5',atempo
12749 Specify a list of drawtext and hue commands in a file.
12751 # show text in the interval 5-10
12752 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
12753 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
12755 # desaturate the image in the interval 15-20
12756 15.0-20.0 [enter] hue s 0,
12757 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
12759 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
12761 # apply an exponential saturation fade-out effect, starting from time 25
12762 25 [enter] hue s exp(25-t)
12765 A filtergraph allowing to read and process the above command list
12766 stored in a file @file{test.cmd}, can be specified with:
12768 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
12773 @section setpts, asetpts
12775 Change the PTS (presentation timestamp) of the input frames.
12777 @code{setpts} works on video frames, @code{asetpts} on audio frames.
12779 This filter accepts the following options:
12784 The expression which is evaluated for each frame to construct its timestamp.
12788 The expression is evaluated through the eval API and can contain the following
12793 frame rate, only defined for constant frame-rate video
12796 The presentation timestamp in input
12799 The count of the input frame for video or the number of consumed samples,
12800 not including the current frame for audio, starting from 0.
12802 @item NB_CONSUMED_SAMPLES
12803 The number of consumed samples, not including the current frame (only
12806 @item NB_SAMPLES, S
12807 The number of samples in the current frame (only audio)
12809 @item SAMPLE_RATE, SR
12810 The audio sample rate.
12813 The PTS of the first frame.
12816 the time in seconds of the first frame
12819 State whether the current frame is interlaced.
12822 the time in seconds of the current frame
12825 original position in the file of the frame, or undefined if undefined
12826 for the current frame
12829 The previous input PTS.
12832 previous input time in seconds
12835 The previous output PTS.
12838 previous output time in seconds
12841 The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
12845 The wallclock (RTC) time at the start of the movie in microseconds.
12848 The timebase of the input timestamps.
12852 @subsection Examples
12856 Start counting PTS from zero
12858 setpts=PTS-STARTPTS
12862 Apply fast motion effect:
12868 Apply slow motion effect:
12874 Set fixed rate of 25 frames per second:
12880 Set fixed rate 25 fps with some jitter:
12882 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
12886 Apply an offset of 10 seconds to the input PTS:
12892 Generate timestamps from a "live source" and rebase onto the current timebase:
12894 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
12898 Generate timestamps by counting samples:
12905 @section settb, asettb
12907 Set the timebase to use for the output frames timestamps.
12908 It is mainly useful for testing timebase configuration.
12910 It accepts the following parameters:
12915 The expression which is evaluated into the output timebase.
12919 The value for @option{tb} is an arithmetic expression representing a
12920 rational. The expression can contain the constants "AVTB" (the default
12921 timebase), "intb" (the input timebase) and "sr" (the sample rate,
12922 audio only). Default value is "intb".
12924 @subsection Examples
12928 Set the timebase to 1/25:
12934 Set the timebase to 1/10:
12940 Set the timebase to 1001/1000:
12946 Set the timebase to 2*intb:
12952 Set the default timebase value:
12959 Convert input audio to a video output representing
12960 frequency spectrum logarithmically (using constant Q transform with
12961 Brown-Puckette algorithm), with musical tone scale, from E0 to D#10 (10 octaves).
12963 The filter accepts the following options:
12967 Specify transform volume (multiplier) expression. The expression can contain
12970 @item frequency, freq, f
12971 the frequency where transform is evaluated
12972 @item timeclamp, tc
12973 value of timeclamp option
12977 @item a_weighting(f)
12978 A-weighting of equal loudness
12979 @item b_weighting(f)
12980 B-weighting of equal loudness
12981 @item c_weighting(f)
12982 C-weighting of equal loudness
12984 Default value is @code{16}.
12987 Specify transform length expression. The expression can contain variables:
12989 @item frequency, freq, f
12990 the frequency where transform is evaluated
12991 @item timeclamp, tc
12992 value of timeclamp option
12994 Default value is @code{384/f*tc/(384/f+tc)}.
12997 Specify the transform timeclamp. At low frequency, there is trade-off between
12998 accuracy in time domain and frequency domain. If timeclamp is lower,
12999 event in time domain is represented more accurately (such as fast bass drum),
13000 otherwise event in frequency domain is represented more accurately
13001 (such as bass guitar). Acceptable value is [0.1, 1.0]. Default value is @code{0.17}.
13004 Specify the transform coeffclamp. If coeffclamp is lower, transform is
13005 more accurate, otherwise transform is faster. Acceptable value is [0.1, 10.0].
13006 Default value is @code{1.0}.
13009 Specify gamma. Lower gamma makes the spectrum more contrast, higher gamma
13010 makes the spectrum having more range. Acceptable value is [1.0, 7.0].
13011 Default value is @code{3.0}.
13014 Specify gamma of bargraph. Acceptable value is [1.0, 7.0].
13015 Default value is @code{1.0}.
13018 Specify font file for use with freetype. If not specified, use embedded font.
13021 Specify font color expression. This is arithmetic expression that should return
13022 integer value 0xRRGGBB. The expression can contain variables:
13024 @item frequency, freq, f
13025 the frequency where transform is evaluated
13026 @item timeclamp, tc
13027 value of timeclamp option
13032 midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
13033 @item r(x), g(x), b(x)
13034 red, green, and blue value of intensity x
13036 Default value is @code{st(0, (midi(f)-59.5)/12);
13037 st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
13038 r(1-ld(1)) + b(ld(1))}
13041 If set to 1 (the default), the video size is 1920x1080 (full HD),
13042 if set to 0, the video size is 960x540. Use this option to make CPU usage lower.
13045 Specify video fps. Default value is @code{25}.
13048 Specify number of transform per frame, so there are fps*count transforms
13049 per second. Note that audio data rate must be divisible by fps*count.
13050 Default value is @code{6}.
13054 @subsection Examples
13058 Playing audio while showing the spectrum:
13060 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
13064 Same as above, but with frame rate 30 fps:
13066 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
13070 Playing at 960x540 and lower CPU usage:
13072 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fullhd=0:count=3 [out0]'
13076 A1 and its harmonics: A1, A2, (near)E3, A3:
13078 ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
13079 asplit[a][out1]; [a] showcqt [out0]'
13083 Same as above, but with more accuracy in frequency domain (and slower):
13085 ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
13086 asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
13090 B-weighting of equal loudness
13092 volume=16*b_weighting(f)
13098 tlength=100/f*tc/(100/f+tc)
13102 Custom fontcolor, C-note is colored green, others are colored blue
13104 fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))'
13108 Custom gamma, now spectrum is linear to the amplitude.
13117 Convert input audio to video output representing the audio power spectrum.
13118 Audio amplitude is on Y-axis while frequency is on X-axis.
13120 The filter accepts the following options:
13124 Specify size of video. For the syntax of this option, check the
13125 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13126 Default is @code{1024x512}.
13130 This set how each frequency bin will be represented.
13132 It accepts the following values:
13138 Default is @code{bar}.
13141 Set amplitude scale.
13143 It accepts the following values:
13157 Default is @code{log}.
13160 Set frequency scale.
13162 It accepts the following values:
13171 Reverse logarithmic scale.
13173 Default is @code{lin}.
13178 It accepts the following values:
13194 Default is @code{w2048}
13197 Set windowing function.
13199 It accepts the following values:
13216 Default is @code{hanning}.
13219 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
13220 which means optimal overlap for selected window function will be picked.
13223 Set time averaging. Setting this to 0 will display current maximal peaks.
13224 Default is @code{1}, which means time averaging is disabled.
13227 Specify list of colors separated by space or by '|' which will be used to
13228 draw channel frequencies. Unrecognized or missing colors will be replaced
13232 @section showspectrum
13234 Convert input audio to a video output, representing the audio frequency
13237 The filter accepts the following options:
13241 Specify the video size for the output. For the syntax of this option, check the
13242 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13243 Default value is @code{640x512}.
13246 Specify how the spectrum should slide along the window.
13248 It accepts the following values:
13251 the samples start again on the left when they reach the right
13253 the samples scroll from right to left
13255 frames are only produced when the samples reach the right
13258 Default value is @code{replace}.
13261 Specify display mode.
13263 It accepts the following values:
13266 all channels are displayed in the same row
13268 all channels are displayed in separate rows
13271 Default value is @samp{combined}.
13274 Specify display color mode.
13276 It accepts the following values:
13279 each channel is displayed in a separate color
13281 each channel is is displayed using the same color scheme
13284 Default value is @samp{channel}.
13287 Specify scale used for calculating intensity color values.
13289 It accepts the following values:
13294 square root, default
13301 Default value is @samp{sqrt}.
13304 Set saturation modifier for displayed colors. Negative values provide
13305 alternative color scheme. @code{0} is no saturation at all.
13306 Saturation must be in [-10.0, 10.0] range.
13307 Default value is @code{1}.
13310 Set window function.
13312 It accepts the following values:
13315 No samples pre-processing (do not expect this to be faster)
13324 Default value is @code{hann}.
13327 The usage is very similar to the showwaves filter; see the examples in that
13330 @subsection Examples
13334 Large window with logarithmic color scaling:
13336 showspectrum=s=1280x480:scale=log
13340 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
13342 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
13343 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
13347 @section showvolume
13349 Convert input audio volume to a video output.
13351 The filter accepts the following options:
13358 Set border width, allowed range is [0, 5]. Default is 1.
13361 Set channel width, allowed range is [40, 1080]. Default is 400.
13364 Set channel height, allowed range is [1, 100]. Default is 20.
13367 Set fade, allowed range is [1, 255]. Default is 20.
13370 Set volume color expression.
13372 The expression can use the following variables:
13376 Current max volume of channel in dB.
13379 Current channel number, starting from 0.
13383 If set, displays channel names. Default is enabled.
13388 Convert input audio to a video output, representing the samples waves.
13390 The filter accepts the following options:
13394 Specify the video size for the output. For the syntax of this option, check the
13395 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13396 Default value is @code{600x240}.
13401 Available values are:
13404 Draw a point for each sample.
13407 Draw a vertical line for each sample.
13410 Draw a point for each sample and a line between them.
13413 Draw a centered vertical line for each sample.
13416 Default value is @code{point}.
13419 Set the number of samples which are printed on the same column. A
13420 larger value will decrease the frame rate. Must be a positive
13421 integer. This option can be set only if the value for @var{rate}
13422 is not explicitly specified.
13425 Set the (approximate) output frame rate. This is done by setting the
13426 option @var{n}. Default value is "25".
13428 @item split_channels
13429 Set if channels should be drawn separately or overlap. Default value is 0.
13433 @subsection Examples
13437 Output the input file audio and the corresponding video representation
13440 amovie=a.mp3,asplit[out0],showwaves[out1]
13444 Create a synthetic signal and show it with showwaves, forcing a
13445 frame rate of 30 frames per second:
13447 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
13451 @section showwavespic
13453 Convert input audio to a single video frame, representing the samples waves.
13455 The filter accepts the following options:
13459 Specify the video size for the output. For the syntax of this option, check the
13460 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13461 Default value is @code{600x240}.
13463 @item split_channels
13464 Set if channels should be drawn separately or overlap. Default value is 0.
13467 @subsection Examples
13471 Extract a channel split representation of the wave form of a whole audio track
13472 in a 1024x800 picture using @command{ffmpeg}:
13474 ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
13478 @section split, asplit
13480 Split input into several identical outputs.
13482 @code{asplit} works with audio input, @code{split} with video.
13484 The filter accepts a single parameter which specifies the number of outputs. If
13485 unspecified, it defaults to 2.
13487 @subsection Examples
13491 Create two separate outputs from the same input:
13493 [in] split [out0][out1]
13497 To create 3 or more outputs, you need to specify the number of
13500 [in] asplit=3 [out0][out1][out2]
13504 Create two separate outputs from the same input, one cropped and
13507 [in] split [splitout1][splitout2];
13508 [splitout1] crop=100:100:0:0 [cropout];
13509 [splitout2] pad=200:200:100:100 [padout];
13513 Create 5 copies of the input audio with @command{ffmpeg}:
13515 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
13521 Receive commands sent through a libzmq client, and forward them to
13522 filters in the filtergraph.
13524 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
13525 must be inserted between two video filters, @code{azmq} between two
13528 To enable these filters you need to install the libzmq library and
13529 headers and configure FFmpeg with @code{--enable-libzmq}.
13531 For more information about libzmq see:
13532 @url{http://www.zeromq.org/}
13534 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
13535 receives messages sent through a network interface defined by the
13536 @option{bind_address} option.
13538 The received message must be in the form:
13540 @var{TARGET} @var{COMMAND} [@var{ARG}]
13543 @var{TARGET} specifies the target of the command, usually the name of
13544 the filter class or a specific filter instance name.
13546 @var{COMMAND} specifies the name of the command for the target filter.
13548 @var{ARG} is optional and specifies the optional argument list for the
13549 given @var{COMMAND}.
13551 Upon reception, the message is processed and the corresponding command
13552 is injected into the filtergraph. Depending on the result, the filter
13553 will send a reply to the client, adopting the format:
13555 @var{ERROR_CODE} @var{ERROR_REASON}
13559 @var{MESSAGE} is optional.
13561 @subsection Examples
13563 Look at @file{tools/zmqsend} for an example of a zmq client which can
13564 be used to send commands processed by these filters.
13566 Consider the following filtergraph generated by @command{ffplay}
13568 ffplay -dumpgraph 1 -f lavfi "
13569 color=s=100x100:c=red [l];
13570 color=s=100x100:c=blue [r];
13571 nullsrc=s=200x100, zmq [bg];
13572 [bg][l] overlay [bg+l];
13573 [bg+l][r] overlay=x=100 "
13576 To change the color of the left side of the video, the following
13577 command can be used:
13579 echo Parsed_color_0 c yellow | tools/zmqsend
13582 To change the right side:
13584 echo Parsed_color_1 c pink | tools/zmqsend
13587 @c man end MULTIMEDIA FILTERS
13589 @chapter Multimedia Sources
13590 @c man begin MULTIMEDIA SOURCES
13592 Below is a description of the currently available multimedia sources.
13596 This is the same as @ref{movie} source, except it selects an audio
13602 Read audio and/or video stream(s) from a movie container.
13604 It accepts the following parameters:
13608 The name of the resource to read (not necessarily a file; it can also be a
13609 device or a stream accessed through some protocol).
13611 @item format_name, f
13612 Specifies the format assumed for the movie to read, and can be either
13613 the name of a container or an input device. If not specified, the
13614 format is guessed from @var{movie_name} or by probing.
13616 @item seek_point, sp
13617 Specifies the seek point in seconds. The frames will be output
13618 starting from this seek point. The parameter is evaluated with
13619 @code{av_strtod}, so the numerical value may be suffixed by an IS
13620 postfix. The default value is "0".
13623 Specifies the streams to read. Several streams can be specified,
13624 separated by "+". The source will then have as many outputs, in the
13625 same order. The syntax is explained in the ``Stream specifiers''
13626 section in the ffmpeg manual. Two special names, "dv" and "da" specify
13627 respectively the default (best suited) video and audio stream. Default
13628 is "dv", or "da" if the filter is called as "amovie".
13630 @item stream_index, si
13631 Specifies the index of the video stream to read. If the value is -1,
13632 the most suitable video stream will be automatically selected. The default
13633 value is "-1". Deprecated. If the filter is called "amovie", it will select
13634 audio instead of video.
13637 Specifies how many times to read the stream in sequence.
13638 If the value is less than 1, the stream will be read again and again.
13639 Default value is "1".
13641 Note that when the movie is looped the source timestamps are not
13642 changed, so it will generate non monotonically increasing timestamps.
13645 It allows overlaying a second video on top of the main input of
13646 a filtergraph, as shown in this graph:
13648 input -----------> deltapts0 --> overlay --> output
13651 movie --> scale--> deltapts1 -------+
13653 @subsection Examples
13657 Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
13658 on top of the input labelled "in":
13660 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
13661 [in] setpts=PTS-STARTPTS [main];
13662 [main][over] overlay=16:16 [out]
13666 Read from a video4linux2 device, and overlay it on top of the input
13669 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
13670 [in] setpts=PTS-STARTPTS [main];
13671 [main][over] overlay=16:16 [out]
13675 Read the first video stream and the audio stream with id 0x81 from
13676 dvd.vob; the video is connected to the pad named "video" and the audio is
13677 connected to the pad named "audio":
13679 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
13683 @c man end MULTIMEDIA SOURCES