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 A gate is mainly used to reduce lower parts of a signal. This kind of signal
647 processing reduces disturbing noise between useful signals.
649 Gating is done by detecting the volume below a chosen level @var{threshold}
650 and divide it by the factor set with @var{ratio}. The bottom of the noise
651 floor is set via @var{range}. Because an exact manipulation of the signal
652 would cause distortion of the waveform the reduction can be levelled over
653 time. This is done by setting @var{attack} and @var{release}.
655 @var{attack} determines how long the signal has to fall below the threshold
656 before any reduction will occur and @var{release} sets the time the signal
657 has to raise above the threshold to reduce the reduction again.
658 Shorter signals than the chosen attack time will be left untouched.
662 Set input level before filtering.
665 Set the level of gain reduction when the signal is below the threshold.
668 If a signal rises above this level the gain reduction is released.
671 Set a ratio about which the signal is reduced.
674 Amount of milliseconds the signal has to rise above the threshold before gain
678 Amount of milliseconds the signal has to fall below the threshold before the
679 reduction is increased again.
682 Set amount of amplification of signal after processing.
685 Curve the sharp knee around the threshold to enter gain reduction more softly.
688 Choose if exact signal should be taken for detection or an RMS like one.
691 Choose if the average level between all channels or the louder channel affects
697 The limiter prevents input signal from raising over a desired threshold.
698 This limiter uses lookahead technology to prevent your signal from distorting.
699 It means that there is a small delay after signal is processed. Keep in mind
700 that the delay it produces is the attack time you set.
702 The filter accepts the following options:
706 Don't let signals above this level pass the limiter. The removed amplitude is
707 added automatically. Default is 1.
710 The limiter will reach its attenuation level in this amount of time in
711 milliseconds. Default is 5 milliseconds.
714 Come back from limiting to attenuation 1.0 in this amount of milliseconds.
715 Default is 50 milliseconds.
718 When gain reduction is always needed ASC takes care of releasing to an
719 average reduction level rather than reaching a reduction of 0 in the release
723 Select how much the release time is affected by ASC, 0 means nearly no changes
724 in release time while 1 produces higher release times.
727 Depending on picked setting it is recommended to upsample input 2x or 4x times
728 with @ref{aresample} before applying this filter.
732 Apply a two-pole all-pass filter with central frequency (in Hz)
733 @var{frequency}, and filter-width @var{width}.
734 An all-pass filter changes the audio's frequency to phase relationship
735 without changing its frequency to amplitude relationship.
737 The filter accepts the following options:
744 Set method to specify band-width of filter.
757 Specify the band-width of a filter in width_type units.
763 Merge two or more audio streams into a single multi-channel stream.
765 The filter accepts the following options:
770 Set the number of inputs. Default is 2.
774 If the channel layouts of the inputs are disjoint, and therefore compatible,
775 the channel layout of the output will be set accordingly and the channels
776 will be reordered as necessary. If the channel layouts of the inputs are not
777 disjoint, the output will have all the channels of the first input then all
778 the channels of the second input, in that order, and the channel layout of
779 the output will be the default value corresponding to the total number of
782 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
783 is FC+BL+BR, then the output will be in 5.1, with the channels in the
784 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
785 first input, b1 is the first channel of the second input).
787 On the other hand, if both input are in stereo, the output channels will be
788 in the default order: a1, a2, b1, b2, and the channel layout will be
789 arbitrarily set to 4.0, which may or may not be the expected value.
791 All inputs must have the same sample rate, and format.
793 If inputs do not have the same duration, the output will stop with the
800 Merge two mono files into a stereo stream:
802 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
806 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
808 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
814 Mixes multiple audio inputs into a single output.
816 Note that this filter only supports float samples (the @var{amerge}
817 and @var{pan} audio filters support many formats). If the @var{amix}
818 input has integer samples then @ref{aresample} will be automatically
819 inserted to perform the conversion to float samples.
823 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
825 will mix 3 input audio streams to a single output with the same duration as the
826 first input and a dropout transition time of 3 seconds.
828 It accepts the following parameters:
832 The number of inputs. If unspecified, it defaults to 2.
835 How to determine the end-of-stream.
839 The duration of the longest input. (default)
842 The duration of the shortest input.
845 The duration of the first input.
849 @item dropout_transition
850 The transition time, in seconds, for volume renormalization when an input
851 stream ends. The default value is 2 seconds.
857 Pass the audio source unchanged to the output.
861 Pad the end of an audio stream with silence.
863 This can be used together with @command{ffmpeg} @option{-shortest} to
864 extend audio streams to the same length as the video stream.
866 A description of the accepted options follows.
870 Set silence packet size. Default value is 4096.
873 Set the number of samples of silence to add to the end. After the
874 value is reached, the stream is terminated. This option is mutually
875 exclusive with @option{whole_len}.
878 Set the minimum total number of samples in the output audio stream. If
879 the value is longer than the input audio length, silence is added to
880 the end, until the value is reached. This option is mutually exclusive
881 with @option{pad_len}.
884 If neither the @option{pad_len} nor the @option{whole_len} option is
885 set, the filter will add silence to the end of the input stream
892 Add 1024 samples of silence to the end of the input:
898 Make sure the audio output will contain at least 10000 samples, pad
899 the input with silence if required:
905 Use @command{ffmpeg} to pad the audio input with silence, so that the
906 video stream will always result the shortest and will be converted
907 until the end in the output file when using the @option{shortest}
910 ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT
915 Add a phasing effect to the input audio.
917 A phaser filter creates series of peaks and troughs in the frequency spectrum.
918 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
920 A description of the accepted parameters follows.
924 Set input gain. Default is 0.4.
927 Set output gain. Default is 0.74
930 Set delay in milliseconds. Default is 3.0.
933 Set decay. Default is 0.4.
936 Set modulation speed in Hz. Default is 0.5.
939 Set modulation type. Default is triangular.
941 It accepts the following values:
951 Resample the input audio to the specified parameters, using the
952 libswresample library. If none are specified then the filter will
953 automatically convert between its input and output.
955 This filter is also able to stretch/squeeze the audio data to make it match
956 the timestamps or to inject silence / cut out audio to make it match the
957 timestamps, do a combination of both or do neither.
959 The filter accepts the syntax
960 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
961 expresses a sample rate and @var{resampler_options} is a list of
962 @var{key}=@var{value} pairs, separated by ":". See the
963 ffmpeg-resampler manual for the complete list of supported options.
969 Resample the input audio to 44100Hz:
975 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
976 samples per second compensation:
982 @section asetnsamples
984 Set the number of samples per each output audio frame.
986 The last output packet may contain a different number of samples, as
987 the filter will flush all the remaining samples when the input audio
990 The filter accepts the following options:
994 @item nb_out_samples, n
995 Set the number of frames per each output audio frame. The number is
996 intended as the number of samples @emph{per each channel}.
997 Default value is 1024.
1000 If set to 1, the filter will pad the last audio frame with zeroes, so
1001 that the last frame will contain the same number of samples as the
1002 previous ones. Default value is 1.
1005 For example, to set the number of per-frame samples to 1234 and
1006 disable padding for the last frame, use:
1008 asetnsamples=n=1234:p=0
1013 Set the sample rate without altering the PCM data.
1014 This will result in a change of speed and pitch.
1016 The filter accepts the following options:
1019 @item sample_rate, r
1020 Set the output sample rate. Default is 44100 Hz.
1025 Show a line containing various information for each input audio frame.
1026 The input audio is not modified.
1028 The shown line contains a sequence of key/value pairs of the form
1029 @var{key}:@var{value}.
1031 The following values are shown in the output:
1035 The (sequential) number of the input frame, starting from 0.
1038 The presentation timestamp of the input frame, in time base units; the time base
1039 depends on the filter input pad, and is usually 1/@var{sample_rate}.
1042 The presentation timestamp of the input frame in seconds.
1045 position of the frame in the input stream, -1 if this information in
1046 unavailable and/or meaningless (for example in case of synthetic audio)
1055 The sample rate for the audio frame.
1058 The number of samples (per channel) in the frame.
1061 The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
1062 audio, the data is treated as if all the planes were concatenated.
1064 @item plane_checksums
1065 A list of Adler-32 checksums for each data plane.
1071 Display time domain statistical information about the audio channels.
1072 Statistics are calculated and displayed for each audio channel and,
1073 where applicable, an overall figure is also given.
1075 It accepts the following option:
1078 Short window length in seconds, used for peak and trough RMS measurement.
1079 Default is @code{0.05} (50 milliseconds). Allowed range is @code{[0.1 - 10]}.
1083 Set metadata injection. All the metadata keys are prefixed with @code{lavfi.astats.X},
1084 where @code{X} is channel number starting from 1 or string @code{Overall}. Default is
1087 Available keys for each channel are:
1118 For example full key look like this @code{lavfi.astats.1.DC_offset} or
1119 this @code{lavfi.astats.Overall.Peak_count}.
1121 For description what each key means read bellow.
1124 Set number of frame after which stats are going to be recalculated.
1125 Default is disabled.
1128 A description of each shown parameter follows:
1132 Mean amplitude displacement from zero.
1135 Minimal sample level.
1138 Maximal sample level.
1140 @item Min difference
1141 Minimal difference between two consecutive samples.
1143 @item Max difference
1144 Maximal difference between two consecutive samples.
1146 @item Mean difference
1147 Mean difference between two consecutive samples.
1148 The average of each difference between two consecutive samples.
1152 Standard peak and RMS level measured in dBFS.
1156 Peak and trough values for RMS level measured over a short window.
1159 Standard ratio of peak to RMS level (note: not in dB).
1162 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
1163 (i.e. either @var{Min level} or @var{Max level}).
1166 Number of occasions (not the number of samples) that the signal attained either
1167 @var{Min level} or @var{Max level}.
1170 Overall bit depth of audio. Number of bits used for each sample.
1173 @section astreamsync
1175 Forward two audio streams and control the order the buffers are forwarded.
1177 The filter accepts the following options:
1181 Set the expression deciding which stream should be
1182 forwarded next: if the result is negative, the first stream is forwarded; if
1183 the result is positive or zero, the second stream is forwarded. It can use
1184 the following variables:
1188 number of buffers forwarded so far on each stream
1190 number of samples forwarded so far on each stream
1192 current timestamp of each stream
1195 The default value is @code{t1-t2}, which means to always forward the stream
1196 that has a smaller timestamp.
1199 @subsection Examples
1201 Stress-test @code{amerge} by randomly sending buffers on the wrong
1202 input, while avoiding too much of a desynchronization:
1204 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
1205 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
1211 Synchronize audio data with timestamps by squeezing/stretching it and/or
1212 dropping samples/adding silence when needed.
1214 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1216 It accepts the following parameters:
1220 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1221 by default. When disabled, time gaps are covered with silence.
1224 The minimum difference between timestamps and audio data (in seconds) to trigger
1225 adding/dropping samples. The default value is 0.1. If you get an imperfect
1226 sync with this filter, try setting this parameter to 0.
1229 The maximum compensation in samples per second. Only relevant with compensate=1.
1230 The default value is 500.
1233 Assume that the first PTS should be this value. The time base is 1 / sample
1234 rate. This allows for padding/trimming at the start of the stream. By default,
1235 no assumption is made about the first frame's expected PTS, so no padding or
1236 trimming is done. For example, this could be set to 0 to pad the beginning with
1237 silence if an audio stream starts after the video stream or to trim any samples
1238 with a negative PTS due to encoder delay.
1246 The filter accepts exactly one parameter, the audio tempo. If not
1247 specified then the filter will assume nominal 1.0 tempo. Tempo must
1248 be in the [0.5, 2.0] range.
1250 @subsection Examples
1254 Slow down audio to 80% tempo:
1260 To speed up audio to 125% tempo:
1268 Trim the input so that the output contains one continuous subpart of the input.
1270 It accepts the following parameters:
1273 Timestamp (in seconds) of the start of the section to keep. I.e. the audio
1274 sample with the timestamp @var{start} will be the first sample in the output.
1277 Specify time of the first audio sample that will be dropped, i.e. the
1278 audio sample immediately preceding the one with the timestamp @var{end} will be
1279 the last sample in the output.
1282 Same as @var{start}, except this option sets the start timestamp in samples
1286 Same as @var{end}, except this option sets the end timestamp in samples instead
1290 The maximum duration of the output in seconds.
1293 The number of the first sample that should be output.
1296 The number of the first sample that should be dropped.
1299 @option{start}, @option{end}, and @option{duration} are expressed as time
1300 duration specifications; see
1301 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
1303 Note that the first two sets of the start/end options and the @option{duration}
1304 option look at the frame timestamp, while the _sample options simply count the
1305 samples that pass through the filter. So start/end_pts and start/end_sample will
1306 give different results when the timestamps are wrong, inexact or do not start at
1307 zero. Also note that this filter does not modify the timestamps. If you wish
1308 to have the output timestamps start at zero, insert the asetpts filter after the
1311 If multiple start or end options are set, this filter tries to be greedy and
1312 keep all samples that match at least one of the specified constraints. To keep
1313 only the part that matches all the constraints at once, chain multiple atrim
1316 The defaults are such that all the input is kept. So it is possible to set e.g.
1317 just the end values to keep everything before the specified time.
1322 Drop everything except the second minute of input:
1324 ffmpeg -i INPUT -af atrim=60:120
1328 Keep only the first 1000 samples:
1330 ffmpeg -i INPUT -af atrim=end_sample=1000
1337 Apply a two-pole Butterworth band-pass filter with central
1338 frequency @var{frequency}, and (3dB-point) band-width width.
1339 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1340 instead of the default: constant 0dB peak gain.
1341 The filter roll off at 6dB per octave (20dB per decade).
1343 The filter accepts the following options:
1347 Set the filter's central frequency. Default is @code{3000}.
1350 Constant skirt gain if set to 1. Defaults to 0.
1353 Set method to specify band-width of filter.
1366 Specify the band-width of a filter in width_type units.
1371 Apply a two-pole Butterworth band-reject filter with central
1372 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1373 The filter roll off at 6dB per octave (20dB per decade).
1375 The filter accepts the following options:
1379 Set the filter's central frequency. Default is @code{3000}.
1382 Set method to specify band-width of filter.
1395 Specify the band-width of a filter in width_type units.
1400 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1401 shelving filter with a response similar to that of a standard
1402 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1404 The filter accepts the following options:
1408 Give the gain at 0 Hz. Its useful range is about -20
1409 (for a large cut) to +20 (for a large boost).
1410 Beware of clipping when using a positive gain.
1413 Set the filter's central frequency and so can be used
1414 to extend or reduce the frequency range to be boosted or cut.
1415 The default value is @code{100} Hz.
1418 Set method to specify band-width of filter.
1431 Determine how steep is the filter's shelf transition.
1436 Apply a biquad IIR filter with the given coefficients.
1437 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1438 are the numerator and denominator coefficients respectively.
1441 Bauer stereo to binaural transformation, which improves headphone listening of
1442 stereo audio records.
1444 It accepts the following parameters:
1448 Pre-defined crossfeed level.
1452 Default level (fcut=700, feed=50).
1455 Chu Moy circuit (fcut=700, feed=60).
1458 Jan Meier circuit (fcut=650, feed=95).
1463 Cut frequency (in Hz).
1472 Remap input channels to new locations.
1474 It accepts the following parameters:
1476 @item channel_layout
1477 The channel layout of the output stream.
1480 Map channels from input to output. The argument is a '|'-separated list of
1481 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1482 @var{in_channel} form. @var{in_channel} can be either the name of the input
1483 channel (e.g. FL for front left) or its index in the input channel layout.
1484 @var{out_channel} is the name of the output channel or its index in the output
1485 channel layout. If @var{out_channel} is not given then it is implicitly an
1486 index, starting with zero and increasing by one for each mapping.
1489 If no mapping is present, the filter will implicitly map input channels to
1490 output channels, preserving indices.
1492 For example, assuming a 5.1+downmix input MOV file,
1494 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1496 will create an output WAV file tagged as stereo from the downmix channels of
1499 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1501 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
1504 @section channelsplit
1506 Split each channel from an input audio stream into a separate output stream.
1508 It accepts the following parameters:
1510 @item channel_layout
1511 The channel layout of the input stream. The default is "stereo".
1514 For example, assuming a stereo input MP3 file,
1516 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1518 will create an output Matroska file with two audio streams, one containing only
1519 the left channel and the other the right channel.
1521 Split a 5.1 WAV file into per-channel files:
1523 ffmpeg -i in.wav -filter_complex
1524 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1525 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1526 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1531 Add a chorus effect to the audio.
1533 Can make a single vocal sound like a chorus, but can also be applied to instrumentation.
1535 Chorus resembles an echo effect with a short delay, but whereas with echo the delay is
1536 constant, with chorus, it is varied using using sinusoidal or triangular modulation.
1537 The modulation depth defines the range the modulated delay is played before or after
1538 the delay. Hence the delayed sound will sound slower or faster, that is the delayed
1539 sound tuned around the original one, like in a chorus where some vocals are slightly
1542 It accepts the following parameters:
1545 Set input gain. Default is 0.4.
1548 Set output gain. Default is 0.4.
1551 Set delays. A typical delay is around 40ms to 60ms.
1563 @subsection Examples
1569 chorus=0.7:0.9:55:0.4:0.25:2
1575 chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3
1579 Fuller sounding chorus with three delays:
1581 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
1586 Compress or expand the audio's dynamic range.
1588 It accepts the following parameters:
1594 A list of times in seconds for each channel over which the instantaneous level
1595 of the input signal is averaged to determine its volume. @var{attacks} refers to
1596 increase of volume and @var{decays} refers to decrease of volume. For most
1597 situations, the attack time (response to the audio getting louder) should be
1598 shorter than the decay time, because the human ear is more sensitive to sudden
1599 loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
1600 a typical value for decay is 0.8 seconds.
1601 If specified number of attacks & decays is lower than number of channels, the last
1602 set attack/decay will be used for all remaining channels.
1605 A list of points for the transfer function, specified in dB relative to the
1606 maximum possible signal amplitude. Each key points list must be defined using
1607 the following syntax: @code{x0/y0|x1/y1|x2/y2|....} or
1608 @code{x0/y0 x1/y1 x2/y2 ....}
1610 The input values must be in strictly increasing order but the transfer function
1611 does not have to be monotonically rising. The point @code{0/0} is assumed but
1612 may be overridden (by @code{0/out-dBn}). Typical values for the transfer
1613 function are @code{-70/-70|-60/-20}.
1616 Set the curve radius in dB for all joints. It defaults to 0.01.
1619 Set the additional gain in dB to be applied at all points on the transfer
1620 function. This allows for easy adjustment of the overall gain.
1624 Set an initial volume, in dB, to be assumed for each channel when filtering
1625 starts. This permits the user to supply a nominal level initially, so that, for
1626 example, a very large gain is not applied to initial signal levels before the
1627 companding has begun to operate. A typical value for audio which is initially
1628 quiet is -90 dB. It defaults to 0.
1631 Set a delay, in seconds. The input audio is analyzed immediately, but audio is
1632 delayed before being fed to the volume adjuster. Specifying a delay
1633 approximately equal to the attack/decay times allows the filter to effectively
1634 operate in predictive rather than reactive mode. It defaults to 0.
1638 @subsection Examples
1642 Make music with both quiet and loud passages suitable for listening to in a
1645 compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
1648 Another example for audio with whisper and explosion parts:
1650 compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0
1654 A noise gate for when the noise is at a lower level than the signal:
1656 compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
1660 Here is another noise gate, this time for when the noise is at a higher level
1661 than the signal (making it, in some ways, similar to squelch):
1663 compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
1668 Apply a DC shift to the audio.
1670 This can be useful to remove a DC offset (caused perhaps by a hardware problem
1671 in the recording chain) from the audio. The effect of a DC offset is reduced
1672 headroom and hence volume. The @ref{astats} filter can be used to determine if
1673 a signal has a DC offset.
1677 Set the DC shift, allowed range is [-1, 1]. It indicates the amount to shift
1681 Optional. It should have a value much less than 1 (e.g. 0.05 or 0.02) and is
1682 used to prevent clipping.
1686 Dynamic Audio Normalizer.
1688 This filter applies a certain amount of gain to the input audio in order
1689 to bring its peak magnitude to a target level (e.g. 0 dBFS). However, in
1690 contrast to more "simple" normalization algorithms, the Dynamic Audio
1691 Normalizer *dynamically* re-adjusts the gain factor to the input audio.
1692 This allows for applying extra gain to the "quiet" sections of the audio
1693 while avoiding distortions or clipping the "loud" sections. In other words:
1694 The Dynamic Audio Normalizer will "even out" the volume of quiet and loud
1695 sections, in the sense that the volume of each section is brought to the
1696 same target level. Note, however, that the Dynamic Audio Normalizer achieves
1697 this goal *without* applying "dynamic range compressing". It will retain 100%
1698 of the dynamic range *within* each section of the audio file.
1702 Set the frame length in milliseconds. In range from 10 to 8000 milliseconds.
1703 Default is 500 milliseconds.
1704 The Dynamic Audio Normalizer processes the input audio in small chunks,
1705 referred to as frames. This is required, because a peak magnitude has no
1706 meaning for just a single sample value. Instead, we need to determine the
1707 peak magnitude for a contiguous sequence of sample values. While a "standard"
1708 normalizer would simply use the peak magnitude of the complete file, the
1709 Dynamic Audio Normalizer determines the peak magnitude individually for each
1710 frame. The length of a frame is specified in milliseconds. By default, the
1711 Dynamic Audio Normalizer uses a frame length of 500 milliseconds, which has
1712 been found to give good results with most files.
1713 Note that the exact frame length, in number of samples, will be determined
1714 automatically, based on the sampling rate of the individual input audio file.
1717 Set the Gaussian filter window size. In range from 3 to 301, must be odd
1718 number. Default is 31.
1719 Probably the most important parameter of the Dynamic Audio Normalizer is the
1720 @code{window size} of the Gaussian smoothing filter. The filter's window size
1721 is specified in frames, centered around the current frame. For the sake of
1722 simplicity, this must be an odd number. Consequently, the default value of 31
1723 takes into account the current frame, as well as the 15 preceding frames and
1724 the 15 subsequent frames. Using a larger window results in a stronger
1725 smoothing effect and thus in less gain variation, i.e. slower gain
1726 adaptation. Conversely, using a smaller window results in a weaker smoothing
1727 effect and thus in more gain variation, i.e. faster gain adaptation.
1728 In other words, the more you increase this value, the more the Dynamic Audio
1729 Normalizer will behave like a "traditional" normalization filter. On the
1730 contrary, the more you decrease this value, the more the Dynamic Audio
1731 Normalizer will behave like a dynamic range compressor.
1734 Set the target peak value. This specifies the highest permissible magnitude
1735 level for the normalized audio input. This filter will try to approach the
1736 target peak magnitude as closely as possible, but at the same time it also
1737 makes sure that the normalized signal will never exceed the peak magnitude.
1738 A frame's maximum local gain factor is imposed directly by the target peak
1739 magnitude. The default value is 0.95 and thus leaves a headroom of 5%*.
1740 It is not recommended to go above this value.
1743 Set the maximum gain factor. In range from 1.0 to 100.0. Default is 10.0.
1744 The Dynamic Audio Normalizer determines the maximum possible (local) gain
1745 factor for each input frame, i.e. the maximum gain factor that does not
1746 result in clipping or distortion. The maximum gain factor is determined by
1747 the frame's highest magnitude sample. However, the Dynamic Audio Normalizer
1748 additionally bounds the frame's maximum gain factor by a predetermined
1749 (global) maximum gain factor. This is done in order to avoid excessive gain
1750 factors in "silent" or almost silent frames. By default, the maximum gain
1751 factor is 10.0, For most inputs the default value should be sufficient and
1752 it usually is not recommended to increase this value. Though, for input
1753 with an extremely low overall volume level, it may be necessary to allow even
1754 higher gain factors. Note, however, that the Dynamic Audio Normalizer does
1755 not simply apply a "hard" threshold (i.e. cut off values above the threshold).
1756 Instead, a "sigmoid" threshold function will be applied. This way, the
1757 gain factors will smoothly approach the threshold value, but never exceed that
1761 Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 - disabled.
1762 By default, the Dynamic Audio Normalizer performs "peak" normalization.
1763 This means that the maximum local gain factor for each frame is defined
1764 (only) by the frame's highest magnitude sample. This way, the samples can
1765 be amplified as much as possible without exceeding the maximum signal
1766 level, i.e. without clipping. Optionally, however, the Dynamic Audio
1767 Normalizer can also take into account the frame's root mean square,
1768 abbreviated RMS. In electrical engineering, the RMS is commonly used to
1769 determine the power of a time-varying signal. It is therefore considered
1770 that the RMS is a better approximation of the "perceived loudness" than
1771 just looking at the signal's peak magnitude. Consequently, by adjusting all
1772 frames to a constant RMS value, a uniform "perceived loudness" can be
1773 established. If a target RMS value has been specified, a frame's local gain
1774 factor is defined as the factor that would result in exactly that RMS value.
1775 Note, however, that the maximum local gain factor is still restricted by the
1776 frame's highest magnitude sample, in order to prevent clipping.
1779 Enable channels coupling. By default is enabled.
1780 By default, the Dynamic Audio Normalizer will amplify all channels by the same
1781 amount. This means the same gain factor will be applied to all channels, i.e.
1782 the maximum possible gain factor is determined by the "loudest" channel.
1783 However, in some recordings, it may happen that the volume of the different
1784 channels is uneven, e.g. one channel may be "quieter" than the other one(s).
1785 In this case, this option can be used to disable the channel coupling. This way,
1786 the gain factor will be determined independently for each channel, depending
1787 only on the individual channel's highest magnitude sample. This allows for
1788 harmonizing the volume of the different channels.
1791 Enable DC bias correction. By default is disabled.
1792 An audio signal (in the time domain) is a sequence of sample values.
1793 In the Dynamic Audio Normalizer these sample values are represented in the
1794 -1.0 to 1.0 range, regardless of the original input format. Normally, the
1795 audio signal, or "waveform", should be centered around the zero point.
1796 That means if we calculate the mean value of all samples in a file, or in a
1797 single frame, then the result should be 0.0 or at least very close to that
1798 value. If, however, there is a significant deviation of the mean value from
1799 0.0, in either positive or negative direction, this is referred to as a
1800 DC bias or DC offset. Since a DC bias is clearly undesirable, the Dynamic
1801 Audio Normalizer provides optional DC bias correction.
1802 With DC bias correction enabled, the Dynamic Audio Normalizer will determine
1803 the mean value, or "DC correction" offset, of each input frame and subtract
1804 that value from all of the frame's sample values which ensures those samples
1805 are centered around 0.0 again. Also, in order to avoid "gaps" at the frame
1806 boundaries, the DC correction offset values will be interpolated smoothly
1807 between neighbouring frames.
1810 Enable alternative boundary mode. By default is disabled.
1811 The Dynamic Audio Normalizer takes into account a certain neighbourhood
1812 around each frame. This includes the preceding frames as well as the
1813 subsequent frames. However, for the "boundary" frames, located at the very
1814 beginning and at the very end of the audio file, not all neighbouring
1815 frames are available. In particular, for the first few frames in the audio
1816 file, the preceding frames are not known. And, similarly, for the last few
1817 frames in the audio file, the subsequent frames are not known. Thus, the
1818 question arises which gain factors should be assumed for the missing frames
1819 in the "boundary" region. The Dynamic Audio Normalizer implements two modes
1820 to deal with this situation. The default boundary mode assumes a gain factor
1821 of exactly 1.0 for the missing frames, resulting in a smooth "fade in" and
1822 "fade out" at the beginning and at the end of the input, respectively.
1825 Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
1826 By default, the Dynamic Audio Normalizer does not apply "traditional"
1827 compression. This means that signal peaks will not be pruned and thus the
1828 full dynamic range will be retained within each local neighbourhood. However,
1829 in some cases it may be desirable to combine the Dynamic Audio Normalizer's
1830 normalization algorithm with a more "traditional" compression.
1831 For this purpose, the Dynamic Audio Normalizer provides an optional compression
1832 (thresholding) function. If (and only if) the compression feature is enabled,
1833 all input frames will be processed by a soft knee thresholding function prior
1834 to the actual normalization process. Put simply, the thresholding function is
1835 going to prune all samples whose magnitude exceeds a certain threshold value.
1836 However, the Dynamic Audio Normalizer does not simply apply a fixed threshold
1837 value. Instead, the threshold value will be adjusted for each individual
1839 In general, smaller parameters result in stronger compression, and vice versa.
1840 Values below 3.0 are not recommended, because audible distortion may appear.
1845 Make audio easier to listen to on headphones.
1847 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1848 so that when listened to on headphones the stereo image is moved from
1849 inside your head (standard for headphones) to outside and in front of
1850 the listener (standard for speakers).
1856 Apply a two-pole peaking equalisation (EQ) filter. With this
1857 filter, the signal-level at and around a selected frequency can
1858 be increased or decreased, whilst (unlike bandpass and bandreject
1859 filters) that at all other frequencies is unchanged.
1861 In order to produce complex equalisation curves, this filter can
1862 be given several times, each with a different central frequency.
1864 The filter accepts the following options:
1868 Set the filter's central frequency in Hz.
1871 Set method to specify band-width of filter.
1884 Specify the band-width of a filter in width_type units.
1887 Set the required gain or attenuation in dB.
1888 Beware of clipping when using a positive gain.
1891 @subsection Examples
1894 Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
1896 equalizer=f=1000:width_type=h:width=200:g=-10
1900 Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
1902 equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
1906 @section extrastereo
1908 Linearly increases the difference between left and right channels which
1909 adds some sort of "live" effect to playback.
1911 The filter accepts the following option:
1915 Sets the difference coefficient (default: 2.5). 0.0 means mono sound
1916 (average of both channels), with 1.0 sound will be unchanged, with
1917 -1.0 left and right channels will be swapped.
1920 Enable clipping. By default is enabled.
1924 Apply a flanging effect to the audio.
1926 The filter accepts the following options:
1930 Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
1933 Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2.
1936 Set percentage regeneration (delayed signal feedback). Range from -95 to 95.
1940 Set percentage of delayed signal mixed with original. Range from 0 to 100.
1941 Default value is 71.
1944 Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
1947 Set swept wave shape, can be @var{triangular} or @var{sinusoidal}.
1948 Default value is @var{sinusoidal}.
1951 Set swept wave percentage-shift for multi channel. Range from 0 to 100.
1952 Default value is 25.
1955 Set delay-line interpolation, @var{linear} or @var{quadratic}.
1956 Default is @var{linear}.
1961 Apply a high-pass filter with 3dB point frequency.
1962 The filter can be either single-pole, or double-pole (the default).
1963 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1965 The filter accepts the following options:
1969 Set frequency in Hz. Default is 3000.
1972 Set number of poles. Default is 2.
1975 Set method to specify band-width of filter.
1988 Specify the band-width of a filter in width_type units.
1989 Applies only to double-pole filter.
1990 The default is 0.707q and gives a Butterworth response.
1995 Join multiple input streams into one multi-channel stream.
1997 It accepts the following parameters:
2001 The number of input streams. It defaults to 2.
2003 @item channel_layout
2004 The desired output channel layout. It defaults to stereo.
2007 Map channels from inputs to output. The argument is a '|'-separated list of
2008 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
2009 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
2010 can be either the name of the input channel (e.g. FL for front left) or its
2011 index in the specified input stream. @var{out_channel} is the name of the output
2015 The filter will attempt to guess the mappings when they are not specified
2016 explicitly. It does so by first trying to find an unused matching input channel
2017 and if that fails it picks the first unused input channel.
2019 Join 3 inputs (with properly set channel layouts):
2021 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
2024 Build a 5.1 output from 6 single-channel streams:
2026 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
2027 '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'
2033 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
2035 To enable compilation of this filter you need to configure FFmpeg with
2036 @code{--enable-ladspa}.
2040 Specifies the name of LADSPA plugin library to load. If the environment
2041 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
2042 each one of the directories specified by the colon separated list in
2043 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
2044 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
2045 @file{/usr/lib/ladspa/}.
2048 Specifies the plugin within the library. Some libraries contain only
2049 one plugin, but others contain many of them. If this is not set filter
2050 will list all available plugins within the specified library.
2053 Set the '|' separated list of controls which are zero or more floating point
2054 values that determine the behavior of the loaded plugin (for example delay,
2056 Controls need to be defined using the following syntax:
2057 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
2058 @var{valuei} is the value set on the @var{i}-th control.
2059 Alternatively they can be also defined using the following syntax:
2060 @var{value0}|@var{value1}|@var{value2}|..., where
2061 @var{valuei} is the value set on the @var{i}-th control.
2062 If @option{controls} is set to @code{help}, all available controls and
2063 their valid ranges are printed.
2065 @item sample_rate, s
2066 Specify the sample rate, default to 44100. Only used if plugin have
2070 Set the number of samples per channel per each output frame, default
2071 is 1024. Only used if plugin have zero inputs.
2074 Set the minimum duration of the sourced audio. See
2075 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2076 for the accepted syntax.
2077 Note that the resulting duration may be greater than the specified duration,
2078 as the generated audio is always cut at the end of a complete frame.
2079 If not specified, or the expressed duration is negative, the audio is
2080 supposed to be generated forever.
2081 Only used if plugin have zero inputs.
2085 @subsection Examples
2089 List all available plugins within amp (LADSPA example plugin) library:
2095 List all available controls and their valid ranges for @code{vcf_notch}
2096 plugin from @code{VCF} library:
2098 ladspa=f=vcf:p=vcf_notch:c=help
2102 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
2105 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
2109 Add reverberation to the audio using TAP-plugins
2110 (Tom's Audio Processing plugins):
2112 ladspa=file=tap_reverb:tap_reverb
2116 Generate white noise, with 0.2 amplitude:
2118 ladspa=file=cmt:noise_source_white:c=c0=.2
2122 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
2123 @code{C* Audio Plugin Suite} (CAPS) library:
2125 ladspa=file=caps:Click:c=c1=20'
2129 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
2131 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
2135 Increase volume by 20dB using fast lookahead limiter from Steve Harris
2136 @code{SWH Plugins} collection:
2138 ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2
2142 Attenuate low frequencies using Multiband EQ from Steve Harris
2143 @code{SWH Plugins} collection:
2145 ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0
2149 @subsection Commands
2151 This filter supports the following commands:
2154 Modify the @var{N}-th control value.
2156 If the specified value is not valid, it is ignored and prior one is kept.
2161 Apply a low-pass filter with 3dB point frequency.
2162 The filter can be either single-pole or double-pole (the default).
2163 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
2165 The filter accepts the following options:
2169 Set frequency in Hz. Default is 500.
2172 Set number of poles. Default is 2.
2175 Set method to specify band-width of filter.
2188 Specify the band-width of a filter in width_type units.
2189 Applies only to double-pole filter.
2190 The default is 0.707q and gives a Butterworth response.
2196 Mix channels with specific gain levels. The filter accepts the output
2197 channel layout followed by a set of channels definitions.
2199 This filter is also designed to efficiently remap the channels of an audio
2202 The filter accepts parameters of the form:
2203 "@var{l}|@var{outdef}|@var{outdef}|..."
2207 output channel layout or number of channels
2210 output channel specification, of the form:
2211 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
2214 output channel to define, either a channel name (FL, FR, etc.) or a channel
2215 number (c0, c1, etc.)
2218 multiplicative coefficient for the channel, 1 leaving the volume unchanged
2221 input channel to use, see out_name for details; it is not possible to mix
2222 named and numbered input channels
2225 If the `=' in a channel specification is replaced by `<', then the gains for
2226 that specification will be renormalized so that the total is 1, thus
2227 avoiding clipping noise.
2229 @subsection Mixing examples
2231 For example, if you want to down-mix from stereo to mono, but with a bigger
2232 factor for the left channel:
2234 pan=1c|c0=0.9*c0+0.1*c1
2237 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
2238 7-channels surround:
2240 pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
2243 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
2244 that should be preferred (see "-ac" option) unless you have very specific
2247 @subsection Remapping examples
2249 The channel remapping will be effective if, and only if:
2252 @item gain coefficients are zeroes or ones,
2253 @item only one input per channel output,
2256 If all these conditions are satisfied, the filter will notify the user ("Pure
2257 channel mapping detected"), and use an optimized and lossless method to do the
2260 For example, if you have a 5.1 source and want a stereo audio stream by
2261 dropping the extra channels:
2263 pan="stereo| c0=FL | c1=FR"
2266 Given the same source, you can also switch front left and front right channels
2267 and keep the input channel layout:
2269 pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
2272 If the input is a stereo audio stream, you can mute the front left channel (and
2273 still keep the stereo channel layout) with:
2278 Still with a stereo audio stream input, you can copy the right channel in both
2279 front left and right:
2281 pan="stereo| c0=FR | c1=FR"
2286 ReplayGain scanner filter. This filter takes an audio stream as an input and
2287 outputs it unchanged.
2288 At end of filtering it displays @code{track_gain} and @code{track_peak}.
2292 Convert the audio sample format, sample rate and channel layout. It is
2293 not meant to be used directly.
2296 Apply time-stretching and pitch-shifting with librubberband.
2298 The filter accepts the following options:
2302 Set tempo scale factor.
2305 Set pitch scale factor.
2308 Set transients detector.
2309 Possible values are:
2318 Possible values are:
2327 Possible values are:
2334 Set processing window size.
2335 Possible values are:
2344 Possible values are:
2351 Enable formant preservation when shift pitching.
2352 Possible values are:
2360 Possible values are:
2369 Possible values are:
2376 @section sidechaincompress
2378 This filter acts like normal compressor but has the ability to compress
2379 detected signal using second input signal.
2380 It needs two input streams and returns one output stream.
2381 First input stream will be processed depending on second stream signal.
2382 The filtered signal then can be filtered with other filters in later stages of
2383 processing. See @ref{pan} and @ref{amerge} filter.
2385 The filter accepts the following options:
2389 If a signal of second stream raises above this level it will affect the gain
2390 reduction of first stream.
2391 By default is 0.125. Range is between 0.00097563 and 1.
2394 Set a ratio about which the signal is reduced. 1:2 means that if the level
2395 raised 4dB above the threshold, it will be only 2dB above after the reduction.
2396 Default is 2. Range is between 1 and 20.
2399 Amount of milliseconds the signal has to rise above the threshold before gain
2400 reduction starts. Default is 20. Range is between 0.01 and 2000.
2403 Amount of milliseconds the signal has to fall bellow the threshold before
2404 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
2407 Set the amount by how much signal will be amplified after processing.
2408 Default is 2. Range is from 1 and 64.
2411 Curve the sharp knee around the threshold to enter gain reduction more softly.
2412 Default is 2.82843. Range is between 1 and 8.
2415 Choose if the @code{average} level between all channels of side-chain stream
2416 or the louder(@code{maximum}) channel of side-chain stream affects the
2417 reduction. Default is @code{average}.
2420 Should the exact signal be taken in case of @code{peak} or an RMS one in case
2421 of @code{rms}. Default is @code{rms} which is mainly smoother.
2424 @subsection Examples
2428 Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
2429 depending on the signal of 2nd input and later compressed signal to be
2430 merged with 2nd input:
2432 ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
2436 @section silencedetect
2438 Detect silence in an audio stream.
2440 This filter logs a message when it detects that the input audio volume is less
2441 or equal to a noise tolerance value for a duration greater or equal to the
2442 minimum detected noise duration.
2444 The printed times and duration are expressed in seconds.
2446 The filter accepts the following options:
2450 Set silence duration until notification (default is 2 seconds).
2453 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
2454 specified value) or amplitude ratio. Default is -60dB, or 0.001.
2457 @subsection Examples
2461 Detect 5 seconds of silence with -50dB noise tolerance:
2463 silencedetect=n=-50dB:d=5
2467 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
2468 tolerance in @file{silence.mp3}:
2470 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
2474 @section silenceremove
2476 Remove silence from the beginning, middle or end of the audio.
2478 The filter accepts the following options:
2482 This value is used to indicate if audio should be trimmed at beginning of
2483 the audio. A value of zero indicates no silence should be trimmed from the
2484 beginning. When specifying a non-zero value, it trims audio up until it
2485 finds non-silence. Normally, when trimming silence from beginning of audio
2486 the @var{start_periods} will be @code{1} but it can be increased to higher
2487 values to trim all audio up to specific count of non-silence periods.
2488 Default value is @code{0}.
2490 @item start_duration
2491 Specify the amount of time that non-silence must be detected before it stops
2492 trimming audio. By increasing the duration, bursts of noises can be treated
2493 as silence and trimmed off. Default value is @code{0}.
2495 @item start_threshold
2496 This indicates what sample value should be treated as silence. For digital
2497 audio, a value of @code{0} may be fine but for audio recorded from analog,
2498 you may wish to increase the value to account for background noise.
2499 Can be specified in dB (in case "dB" is appended to the specified value)
2500 or amplitude ratio. Default value is @code{0}.
2503 Set the count for trimming silence from the end of audio.
2504 To remove silence from the middle of a file, specify a @var{stop_periods}
2505 that is negative. This value is then treated as a positive value and is
2506 used to indicate the effect should restart processing as specified by
2507 @var{start_periods}, making it suitable for removing periods of silence
2508 in the middle of the audio.
2509 Default value is @code{0}.
2512 Specify a duration of silence that must exist before audio is not copied any
2513 more. By specifying a higher duration, silence that is wanted can be left in
2515 Default value is @code{0}.
2517 @item stop_threshold
2518 This is the same as @option{start_threshold} but for trimming silence from
2520 Can be specified in dB (in case "dB" is appended to the specified value)
2521 or amplitude ratio. Default value is @code{0}.
2524 This indicate that @var{stop_duration} length of audio should be left intact
2525 at the beginning of each period of silence.
2526 For example, if you want to remove long pauses between words but do not want
2527 to remove the pauses completely. Default value is @code{0}.
2531 @subsection Examples
2535 The following example shows how this filter can be used to start a recording
2536 that does not contain the delay at the start which usually occurs between
2537 pressing the record button and the start of the performance:
2539 silenceremove=1:5:0.02
2543 @section stereotools
2545 This filter has some handy utilities to manage stereo signals, for converting
2546 M/S stereo recordings to L/R signal while having control over the parameters
2547 or spreading the stereo image of master track.
2549 The filter accepts the following options:
2553 Set input level before filtering for both channels. Defaults is 1.
2554 Allowed range is from 0.015625 to 64.
2557 Set output level after filtering for both channels. Defaults is 1.
2558 Allowed range is from 0.015625 to 64.
2561 Set input balance between both channels. Default is 0.
2562 Allowed range is from -1 to 1.
2565 Set output balance between both channels. Default is 0.
2566 Allowed range is from -1 to 1.
2569 Enable softclipping. Results in analog distortion instead of harsh digital 0dB
2570 clipping. Disabled by default.
2573 Mute the left channel. Disabled by default.
2576 Mute the right channel. Disabled by default.
2579 Change the phase of the left channel. Disabled by default.
2582 Change the phase of the right channel. Disabled by default.
2585 Set stereo mode. Available values are:
2589 Left/Right to Left/Right, this is default.
2592 Left/Right to Mid/Side.
2595 Mid/Side to Left/Right.
2598 Left/Right to Left/Left.
2601 Left/Right to Right/Right.
2604 Left/Right to Left + Right.
2607 Left/Right to Right/Left.
2611 Set level of side signal. Default is 1.
2612 Allowed range is from 0.015625 to 64.
2615 Set balance of side signal. Default is 0.
2616 Allowed range is from -1 to 1.
2619 Set level of the middle signal. Default is 1.
2620 Allowed range is from 0.015625 to 64.
2623 Set middle signal pan. Default is 0. Allowed range is from -1 to 1.
2626 Set stereo base between mono and inversed channels. Default is 0.
2627 Allowed range is from -1 to 1.
2630 Set delay in milliseconds how much to delay left from right channel and
2631 vice versa. Default is 0. Allowed range is from -20 to 20.
2634 Set S/C level. Default is 1. Allowed range is from 1 to 100.
2637 Set the stereo phase in degrees. Default is 0. Allowed range is from 0 to 360.
2640 @section stereowiden
2642 This filter enhance the stereo effect by suppressing signal common to both
2643 channels and by delaying the signal of left into right and vice versa,
2644 thereby widening the stereo effect.
2646 The filter accepts the following options:
2650 Time in milliseconds of the delay of left signal into right and vice versa.
2651 Default is 20 milliseconds.
2654 Amount of gain in delayed signal into right and vice versa. Gives a delay
2655 effect of left signal in right output and vice versa which gives widening
2656 effect. Default is 0.3.
2659 Cross feed of left into right with inverted phase. This helps in suppressing
2660 the mono. If the value is 1 it will cancel all the signal common to both
2661 channels. Default is 0.3.
2664 Set level of input signal of original channel. Default is 0.8.
2669 Boost or cut treble (upper) frequencies of the audio using a two-pole
2670 shelving filter with a response similar to that of a standard
2671 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
2673 The filter accepts the following options:
2677 Give the gain at whichever is the lower of ~22 kHz and the
2678 Nyquist frequency. Its useful range is about -20 (for a large cut)
2679 to +20 (for a large boost). Beware of clipping when using a positive gain.
2682 Set the filter's central frequency and so can be used
2683 to extend or reduce the frequency range to be boosted or cut.
2684 The default value is @code{3000} Hz.
2687 Set method to specify band-width of filter.
2700 Determine how steep is the filter's shelf transition.
2705 Sinusoidal amplitude modulation.
2707 The filter accepts the following options:
2711 Modulation frequency in Hertz. Modulation frequencies in the subharmonic range
2712 (20 Hz or lower) will result in a tremolo effect.
2713 This filter may also be used as a ring modulator by specifying
2714 a modulation frequency higher than 20 Hz.
2715 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
2718 Depth of modulation as a percentage. Range is 0.0 - 1.0.
2719 Default value is 0.5.
2724 Adjust the input audio volume.
2726 It accepts the following parameters:
2730 Set audio volume expression.
2732 Output values are clipped to the maximum value.
2734 The output audio volume is given by the relation:
2736 @var{output_volume} = @var{volume} * @var{input_volume}
2739 The default value for @var{volume} is "1.0".
2742 This parameter represents the mathematical precision.
2744 It determines which input sample formats will be allowed, which affects the
2745 precision of the volume scaling.
2749 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
2751 32-bit floating-point; this limits input sample format to FLT. (default)
2753 64-bit floating-point; this limits input sample format to DBL.
2757 Choose the behaviour on encountering ReplayGain side data in input frames.
2761 Remove ReplayGain side data, ignoring its contents (the default).
2764 Ignore ReplayGain side data, but leave it in the frame.
2767 Prefer the track gain, if present.
2770 Prefer the album gain, if present.
2773 @item replaygain_preamp
2774 Pre-amplification gain in dB to apply to the selected replaygain gain.
2776 Default value for @var{replaygain_preamp} is 0.0.
2779 Set when the volume expression is evaluated.
2781 It accepts the following values:
2784 only evaluate expression once during the filter initialization, or
2785 when the @samp{volume} command is sent
2788 evaluate expression for each incoming frame
2791 Default value is @samp{once}.
2794 The volume expression can contain the following parameters.
2798 frame number (starting at zero)
2801 @item nb_consumed_samples
2802 number of samples consumed by the filter
2804 number of samples in the current frame
2806 original frame position in the file
2812 PTS at start of stream
2814 time at start of stream
2820 last set volume value
2823 Note that when @option{eval} is set to @samp{once} only the
2824 @var{sample_rate} and @var{tb} variables are available, all other
2825 variables will evaluate to NAN.
2827 @subsection Commands
2829 This filter supports the following commands:
2832 Modify the volume expression.
2833 The command accepts the same syntax of the corresponding option.
2835 If the specified expression is not valid, it is kept at its current
2837 @item replaygain_noclip
2838 Prevent clipping by limiting the gain applied.
2840 Default value for @var{replaygain_noclip} is 1.
2844 @subsection Examples
2848 Halve the input audio volume:
2852 volume=volume=-6.0206dB
2855 In all the above example the named key for @option{volume} can be
2856 omitted, for example like in:
2862 Increase input audio power by 6 decibels using fixed-point precision:
2864 volume=volume=6dB:precision=fixed
2868 Fade volume after time 10 with an annihilation period of 5 seconds:
2870 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
2874 @section volumedetect
2876 Detect the volume of the input video.
2878 The filter has no parameters. The input is not modified. Statistics about
2879 the volume will be printed in the log when the input stream end is reached.
2881 In particular it will show the mean volume (root mean square), maximum
2882 volume (on a per-sample basis), and the beginning of a histogram of the
2883 registered volume values (from the maximum value to a cumulated 1/1000 of
2886 All volumes are in decibels relative to the maximum PCM value.
2888 @subsection Examples
2890 Here is an excerpt of the output:
2892 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
2893 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
2894 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
2895 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
2896 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
2897 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
2898 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
2899 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
2900 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
2906 The mean square energy is approximately -27 dB, or 10^-2.7.
2908 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
2910 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
2913 In other words, raising the volume by +4 dB does not cause any clipping,
2914 raising it by +5 dB causes clipping for 6 samples, etc.
2916 @c man end AUDIO FILTERS
2918 @chapter Audio Sources
2919 @c man begin AUDIO SOURCES
2921 Below is a description of the currently available audio sources.
2925 Buffer audio frames, and make them available to the filter chain.
2927 This source is mainly intended for a programmatic use, in particular
2928 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
2930 It accepts the following parameters:
2934 The timebase which will be used for timestamps of submitted frames. It must be
2935 either a floating-point number or in @var{numerator}/@var{denominator} form.
2938 The sample rate of the incoming audio buffers.
2941 The sample format of the incoming audio buffers.
2942 Either a sample format name or its corresponding integer representation from
2943 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
2945 @item channel_layout
2946 The channel layout of the incoming audio buffers.
2947 Either a channel layout name from channel_layout_map in
2948 @file{libavutil/channel_layout.c} or its corresponding integer representation
2949 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
2952 The number of channels of the incoming audio buffers.
2953 If both @var{channels} and @var{channel_layout} are specified, then they
2958 @subsection Examples
2961 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
2964 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
2965 Since the sample format with name "s16p" corresponds to the number
2966 6 and the "stereo" channel layout corresponds to the value 0x3, this is
2969 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
2974 Generate an audio signal specified by an expression.
2976 This source accepts in input one or more expressions (one for each
2977 channel), which are evaluated and used to generate a corresponding
2980 This source accepts the following options:
2984 Set the '|'-separated expressions list for each separate channel. In case the
2985 @option{channel_layout} option is not specified, the selected channel layout
2986 depends on the number of provided expressions. Otherwise the last
2987 specified expression is applied to the remaining output channels.
2989 @item channel_layout, c
2990 Set the channel layout. The number of channels in the specified layout
2991 must be equal to the number of specified expressions.
2994 Set the minimum duration of the sourced audio. See
2995 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2996 for the accepted syntax.
2997 Note that the resulting duration may be greater than the specified
2998 duration, as the generated audio is always cut at the end of a
3001 If not specified, or the expressed duration is negative, the audio is
3002 supposed to be generated forever.
3005 Set the number of samples per channel per each output frame,
3008 @item sample_rate, s
3009 Specify the sample rate, default to 44100.
3012 Each expression in @var{exprs} can contain the following constants:
3016 number of the evaluated sample, starting from 0
3019 time of the evaluated sample expressed in seconds, starting from 0
3026 @subsection Examples
3036 Generate a sin signal with frequency of 440 Hz, set sample rate to
3039 aevalsrc="sin(440*2*PI*t):s=8000"
3043 Generate a two channels signal, specify the channel layout (Front
3044 Center + Back Center) explicitly:
3046 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
3050 Generate white noise:
3052 aevalsrc="-2+random(0)"
3056 Generate an amplitude modulated signal:
3058 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
3062 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
3064 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
3071 The null audio source, return unprocessed audio frames. It is mainly useful
3072 as a template and to be employed in analysis / debugging tools, or as
3073 the source for filters which ignore the input data (for example the sox
3076 This source accepts the following options:
3080 @item channel_layout, cl
3082 Specifies the channel layout, and can be either an integer or a string
3083 representing a channel layout. The default value of @var{channel_layout}
3086 Check the channel_layout_map definition in
3087 @file{libavutil/channel_layout.c} for the mapping between strings and
3088 channel layout values.
3090 @item sample_rate, r
3091 Specifies the sample rate, and defaults to 44100.
3094 Set the number of samples per requested frames.
3098 @subsection Examples
3102 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
3104 anullsrc=r=48000:cl=4
3108 Do the same operation with a more obvious syntax:
3110 anullsrc=r=48000:cl=mono
3114 All the parameters need to be explicitly defined.
3118 Synthesize a voice utterance using the libflite library.
3120 To enable compilation of this filter you need to configure FFmpeg with
3121 @code{--enable-libflite}.
3123 Note that the flite library is not thread-safe.
3125 The filter accepts the following options:
3130 If set to 1, list the names of the available voices and exit
3131 immediately. Default value is 0.
3134 Set the maximum number of samples per frame. Default value is 512.
3137 Set the filename containing the text to speak.
3140 Set the text to speak.
3143 Set the voice to use for the speech synthesis. Default value is
3144 @code{kal}. See also the @var{list_voices} option.
3147 @subsection Examples
3151 Read from file @file{speech.txt}, and synthesize the text using the
3152 standard flite voice:
3154 flite=textfile=speech.txt
3158 Read the specified text selecting the @code{slt} voice:
3160 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3164 Input text to ffmpeg:
3166 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3170 Make @file{ffplay} speak the specified text, using @code{flite} and
3171 the @code{lavfi} device:
3173 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
3177 For more information about libflite, check:
3178 @url{http://www.speech.cs.cmu.edu/flite/}
3182 Generate an audio signal made of a sine wave with amplitude 1/8.
3184 The audio signal is bit-exact.
3186 The filter accepts the following options:
3191 Set the carrier frequency. Default is 440 Hz.
3193 @item beep_factor, b
3194 Enable a periodic beep every second with frequency @var{beep_factor} times
3195 the carrier frequency. Default is 0, meaning the beep is disabled.
3197 @item sample_rate, r
3198 Specify the sample rate, default is 44100.
3201 Specify the duration of the generated audio stream.
3203 @item samples_per_frame
3204 Set the number of samples per output frame.
3206 The expression can contain the following constants:
3210 The (sequential) number of the output audio frame, starting from 0.
3213 The PTS (Presentation TimeStamp) of the output audio frame,
3214 expressed in @var{TB} units.
3217 The PTS of the output audio frame, expressed in seconds.
3220 The timebase of the output audio frames.
3223 Default is @code{1024}.
3226 @subsection Examples
3231 Generate a simple 440 Hz sine wave:
3237 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
3241 sine=frequency=220:beep_factor=4:duration=5
3245 Generate a 1 kHz sine wave following @code{1602,1601,1602,1601,1602} NTSC
3248 sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
3252 @c man end AUDIO SOURCES
3254 @chapter Audio Sinks
3255 @c man begin AUDIO SINKS
3257 Below is a description of the currently available audio sinks.
3259 @section abuffersink
3261 Buffer audio frames, and make them available to the end of filter chain.
3263 This sink is mainly intended for programmatic use, in particular
3264 through the interface defined in @file{libavfilter/buffersink.h}
3265 or the options system.
3267 It accepts a pointer to an AVABufferSinkContext structure, which
3268 defines the incoming buffers' formats, to be passed as the opaque
3269 parameter to @code{avfilter_init_filter} for initialization.
3272 Null audio sink; do absolutely nothing with the input audio. It is
3273 mainly useful as a template and for use in analysis / debugging
3276 @c man end AUDIO SINKS
3278 @chapter Video Filters
3279 @c man begin VIDEO FILTERS
3281 When you configure your FFmpeg build, you can disable any of the
3282 existing filters using @code{--disable-filters}.
3283 The configure output will show the video filters included in your
3286 Below is a description of the currently available video filters.
3288 @section alphaextract
3290 Extract the alpha component from the input as a grayscale video. This
3291 is especially useful with the @var{alphamerge} filter.
3295 Add or replace the alpha component of the primary input with the
3296 grayscale value of a second input. This is intended for use with
3297 @var{alphaextract} to allow the transmission or storage of frame
3298 sequences that have alpha in a format that doesn't support an alpha
3301 For example, to reconstruct full frames from a normal YUV-encoded video
3302 and a separate video created with @var{alphaextract}, you might use:
3304 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
3307 Since this filter is designed for reconstruction, it operates on frame
3308 sequences without considering timestamps, and terminates when either
3309 input reaches end of stream. This will cause problems if your encoding
3310 pipeline drops frames. If you're trying to apply an image as an
3311 overlay to a video stream, consider the @var{overlay} filter instead.
3315 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
3316 and libavformat to work. On the other hand, it is limited to ASS (Advanced
3317 Substation Alpha) subtitles files.
3319 This filter accepts the following option in addition to the common options from
3320 the @ref{subtitles} filter:
3324 Set the shaping engine
3326 Available values are:
3329 The default libass shaping engine, which is the best available.
3331 Fast, font-agnostic shaper that can do only substitutions
3333 Slower shaper using OpenType for substitutions and positioning
3336 The default is @code{auto}.
3340 Apply an Adaptive Temporal Averaging Denoiser to the video input.
3342 The filter accepts the following options:
3346 Set threshold A for 1st plane. Default is 0.02.
3347 Valid range is 0 to 0.3.
3350 Set threshold B for 1st plane. Default is 0.04.
3351 Valid range is 0 to 5.
3354 Set threshold A for 2nd plane. Default is 0.02.
3355 Valid range is 0 to 0.3.
3358 Set threshold B for 2nd plane. Default is 0.04.
3359 Valid range is 0 to 5.
3362 Set threshold A for 3rd plane. Default is 0.02.
3363 Valid range is 0 to 0.3.
3366 Set threshold B for 3rd plane. Default is 0.04.
3367 Valid range is 0 to 5.
3369 Threshold A is designed to react on abrupt changes in the input signal and
3370 threshold B is designed to react on continuous changes in the input signal.
3373 Set number of frames filter will use for averaging. Default is 33. Must be odd
3374 number in range [5, 129].
3379 Compute the bounding box for the non-black pixels in the input frame
3382 This filter computes the bounding box containing all the pixels with a
3383 luminance value greater than the minimum allowed value.
3384 The parameters describing the bounding box are printed on the filter
3387 The filter accepts the following option:
3391 Set the minimal luminance value. Default is @code{16}.
3394 @section blackdetect
3396 Detect video intervals that are (almost) completely black. Can be
3397 useful to detect chapter transitions, commercials, or invalid
3398 recordings. Output lines contains the time for the start, end and
3399 duration of the detected black interval expressed in seconds.
3401 In order to display the output lines, you need to set the loglevel at
3402 least to the AV_LOG_INFO value.
3404 The filter accepts the following options:
3407 @item black_min_duration, d
3408 Set the minimum detected black duration expressed in seconds. It must
3409 be a non-negative floating point number.
3411 Default value is 2.0.
3413 @item picture_black_ratio_th, pic_th
3414 Set the threshold for considering a picture "black".
3415 Express the minimum value for the ratio:
3417 @var{nb_black_pixels} / @var{nb_pixels}
3420 for which a picture is considered black.
3421 Default value is 0.98.
3423 @item pixel_black_th, pix_th
3424 Set the threshold for considering a pixel "black".
3426 The threshold expresses the maximum pixel luminance value for which a
3427 pixel is considered "black". The provided value is scaled according to
3428 the following equation:
3430 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
3433 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
3434 the input video format, the range is [0-255] for YUV full-range
3435 formats and [16-235] for YUV non full-range formats.
3437 Default value is 0.10.
3440 The following example sets the maximum pixel threshold to the minimum
3441 value, and detects only black intervals of 2 or more seconds:
3443 blackdetect=d=2:pix_th=0.00
3448 Detect frames that are (almost) completely black. Can be useful to
3449 detect chapter transitions or commercials. Output lines consist of
3450 the frame number of the detected frame, the percentage of blackness,
3451 the position in the file if known or -1 and the timestamp in seconds.
3453 In order to display the output lines, you need to set the loglevel at
3454 least to the AV_LOG_INFO value.
3456 It accepts the following parameters:
3461 The percentage of the pixels that have to be below the threshold; it defaults to
3464 @item threshold, thresh
3465 The threshold below which a pixel value is considered black; it defaults to
3470 @section blend, tblend
3472 Blend two video frames into each other.
3474 The @code{blend} filter takes two input streams and outputs one
3475 stream, the first input is the "top" layer and second input is
3476 "bottom" layer. Output terminates when shortest input terminates.
3478 The @code{tblend} (time blend) filter takes two consecutive frames
3479 from one single stream, and outputs the result obtained by blending
3480 the new frame on top of the old frame.
3482 A description of the accepted options follows.
3490 Set blend mode for specific pixel component or all pixel components in case
3491 of @var{all_mode}. Default value is @code{normal}.
3493 Available values for component modes are:
3530 Set blend opacity for specific pixel component or all pixel components in case
3531 of @var{all_opacity}. Only used in combination with pixel component blend modes.
3538 Set blend expression for specific pixel component or all pixel components in case
3539 of @var{all_expr}. Note that related mode options will be ignored if those are set.
3541 The expressions can use the following variables:
3545 The sequential number of the filtered frame, starting from @code{0}.
3549 the coordinates of the current sample
3553 the width and height of currently filtered plane
3557 Width and height scale depending on the currently filtered plane. It is the
3558 ratio between the corresponding luma plane number of pixels and the current
3559 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3560 @code{0.5,0.5} for chroma planes.
3563 Time of the current frame, expressed in seconds.
3566 Value of pixel component at current location for first video frame (top layer).
3569 Value of pixel component at current location for second video frame (bottom layer).
3573 Force termination when the shortest input terminates. Default is
3574 @code{0}. This option is only defined for the @code{blend} filter.
3577 Continue applying the last bottom frame after the end of the stream. A value of
3578 @code{0} disable the filter after the last frame of the bottom layer is reached.
3579 Default is @code{1}. This option is only defined for the @code{blend} filter.
3582 @subsection Examples
3586 Apply transition from bottom layer to top layer in first 10 seconds:
3588 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
3592 Apply 1x1 checkerboard effect:
3594 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
3598 Apply uncover left effect:
3600 blend=all_expr='if(gte(N*SW+X,W),A,B)'
3604 Apply uncover down effect:
3606 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
3610 Apply uncover up-left effect:
3612 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
3616 Display differences between the current and the previous frame:
3618 tblend=all_mode=difference128
3624 Apply a boxblur algorithm to the input video.
3626 It accepts the following parameters:
3630 @item luma_radius, lr
3631 @item luma_power, lp
3632 @item chroma_radius, cr
3633 @item chroma_power, cp
3634 @item alpha_radius, ar
3635 @item alpha_power, ap
3639 A description of the accepted options follows.
3642 @item luma_radius, lr
3643 @item chroma_radius, cr
3644 @item alpha_radius, ar
3645 Set an expression for the box radius in pixels used for blurring the
3646 corresponding input plane.
3648 The radius value must be a non-negative number, and must not be
3649 greater than the value of the expression @code{min(w,h)/2} for the
3650 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
3653 Default value for @option{luma_radius} is "2". If not specified,
3654 @option{chroma_radius} and @option{alpha_radius} default to the
3655 corresponding value set for @option{luma_radius}.
3657 The expressions can contain the following constants:
3661 The input width and height in pixels.
3665 The input chroma image width and height in pixels.
3669 The horizontal and vertical chroma subsample values. For example, for the
3670 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
3673 @item luma_power, lp
3674 @item chroma_power, cp
3675 @item alpha_power, ap
3676 Specify how many times the boxblur filter is applied to the
3677 corresponding plane.
3679 Default value for @option{luma_power} is 2. If not specified,
3680 @option{chroma_power} and @option{alpha_power} default to the
3681 corresponding value set for @option{luma_power}.
3683 A value of 0 will disable the effect.
3686 @subsection Examples
3690 Apply a boxblur filter with the luma, chroma, and alpha radii
3693 boxblur=luma_radius=2:luma_power=1
3698 Set the luma radius to 2, and alpha and chroma radius to 0:
3700 boxblur=2:1:cr=0:ar=0
3704 Set the luma and chroma radii to a fraction of the video dimension:
3706 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
3711 YUV colorspace color/chroma keying.
3713 The filter accepts the following options:
3717 The color which will be replaced with transparency.
3720 Similarity percentage with the key color.
3722 0.01 matches only the exact key color, while 1.0 matches everything.
3727 0.0 makes pixels either fully transparent, or not transparent at all.
3729 Higher values result in semi-transparent pixels, with a higher transparency
3730 the more similar the pixels color is to the key color.
3733 Signals that the color passed is already in YUV instead of RGB.
3735 Litteral colors like "green" or "red" don't make sense with this enabled anymore.
3736 This can be used to pass exact YUV values as hexadecimal numbers.
3739 @subsection Examples
3743 Make every green pixel in the input image transparent:
3745 ffmpeg -i input.png -vf chromakey=green out.png
3749 Overlay a greenscreen-video on top of a static black background.
3751 ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.mkv
3757 Visualize information exported by some codecs.
3759 Some codecs can export information through frames using side-data or other
3760 means. For example, some MPEG based codecs export motion vectors through the
3761 @var{export_mvs} flag in the codec @option{flags2} option.
3763 The filter accepts the following option:
3767 Set motion vectors to visualize.
3769 Available flags for @var{mv} are:
3773 forward predicted MVs of P-frames
3775 forward predicted MVs of B-frames
3777 backward predicted MVs of B-frames
3781 @subsection Examples
3785 Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}:
3787 ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
3791 @section colorbalance
3792 Modify intensity of primary colors (red, green and blue) of input frames.
3794 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
3795 regions for the red-cyan, green-magenta or blue-yellow balance.
3797 A positive adjustment value shifts the balance towards the primary color, a negative
3798 value towards the complementary color.
3800 The filter accepts the following options:
3806 Adjust red, green and blue shadows (darkest pixels).
3811 Adjust red, green and blue midtones (medium pixels).
3816 Adjust red, green and blue highlights (brightest pixels).
3818 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3821 @subsection Examples
3825 Add red color cast to shadows:
3832 RGB colorspace color keying.
3834 The filter accepts the following options:
3838 The color which will be replaced with transparency.
3841 Similarity percentage with the key color.
3843 0.01 matches only the exact key color, while 1.0 matches everything.
3848 0.0 makes pixels either fully transparent, or not transparent at all.
3850 Higher values result in semi-transparent pixels, with a higher transparency
3851 the more similar the pixels color is to the key color.
3854 @subsection Examples
3858 Make every green pixel in the input image transparent:
3860 ffmpeg -i input.png -vf colorkey=green out.png
3864 Overlay a greenscreen-video on top of a static background image.
3866 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
3870 @section colorlevels
3872 Adjust video input frames using levels.
3874 The filter accepts the following options:
3881 Adjust red, green, blue and alpha input black point.
3882 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3888 Adjust red, green, blue and alpha input white point.
3889 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{1}.
3891 Input levels are used to lighten highlights (bright tones), darken shadows
3892 (dark tones), change the balance of bright and dark tones.
3898 Adjust red, green, blue and alpha output black point.
3899 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{0}.
3905 Adjust red, green, blue and alpha output white point.
3906 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{1}.
3908 Output levels allows manual selection of a constrained output level range.
3911 @subsection Examples
3915 Make video output darker:
3917 colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
3923 colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
3927 Make video output lighter:
3929 colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
3933 Increase brightness:
3935 colorlevels=romin=0.5:gomin=0.5:bomin=0.5
3939 @section colorchannelmixer
3941 Adjust video input frames by re-mixing color channels.
3943 This filter modifies a color channel by adding the values associated to
3944 the other channels of the same pixels. For example if the value to
3945 modify is red, the output value will be:
3947 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
3950 The filter accepts the following options:
3957 Adjust contribution of input red, green, blue and alpha channels for output red channel.
3958 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
3964 Adjust contribution of input red, green, blue and alpha channels for output green channel.
3965 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
3971 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
3972 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
3978 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
3979 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
3981 Allowed ranges for options are @code{[-2.0, 2.0]}.
3984 @subsection Examples
3988 Convert source to grayscale:
3990 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
3993 Simulate sepia tones:
3995 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
3999 @section colormatrix
4001 Convert color matrix.
4003 The filter accepts the following options:
4008 Specify the source and destination color matrix. Both values must be
4011 The accepted values are:
4027 For example to convert from BT.601 to SMPTE-240M, use the command:
4029 colormatrix=bt601:smpte240m
4034 Copy the input source unchanged to the output. This is mainly useful for
4039 Crop the input video to given dimensions.
4041 It accepts the following parameters:
4045 The width of the output video. It defaults to @code{iw}.
4046 This expression is evaluated only once during the filter
4047 configuration, or when the @samp{w} or @samp{out_w} command is sent.
4050 The height of the output video. It defaults to @code{ih}.
4051 This expression is evaluated only once during the filter
4052 configuration, or when the @samp{h} or @samp{out_h} command is sent.
4055 The horizontal position, in the input video, of the left edge of the output
4056 video. It defaults to @code{(in_w-out_w)/2}.
4057 This expression is evaluated per-frame.
4060 The vertical position, in the input video, of the top edge of the output video.
4061 It defaults to @code{(in_h-out_h)/2}.
4062 This expression is evaluated per-frame.
4065 If set to 1 will force the output display aspect ratio
4066 to be the same of the input, by changing the output sample aspect
4067 ratio. It defaults to 0.
4070 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
4071 expressions containing the following constants:
4076 The computed values for @var{x} and @var{y}. They are evaluated for
4081 The input width and height.
4085 These are the same as @var{in_w} and @var{in_h}.
4089 The output (cropped) width and height.
4093 These are the same as @var{out_w} and @var{out_h}.
4096 same as @var{iw} / @var{ih}
4099 input sample aspect ratio
4102 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4106 horizontal and vertical chroma subsample values. For example for the
4107 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4110 The number of the input frame, starting from 0.
4113 the position in the file of the input frame, NAN if unknown
4116 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
4120 The expression for @var{out_w} may depend on the value of @var{out_h},
4121 and the expression for @var{out_h} may depend on @var{out_w}, but they
4122 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
4123 evaluated after @var{out_w} and @var{out_h}.
4125 The @var{x} and @var{y} parameters specify the expressions for the
4126 position of the top-left corner of the output (non-cropped) area. They
4127 are evaluated for each frame. If the evaluated value is not valid, it
4128 is approximated to the nearest valid value.
4130 The expression for @var{x} may depend on @var{y}, and the expression
4131 for @var{y} may depend on @var{x}.
4133 @subsection Examples
4137 Crop area with size 100x100 at position (12,34).
4142 Using named options, the example above becomes:
4144 crop=w=100:h=100:x=12:y=34
4148 Crop the central input area with size 100x100:
4154 Crop the central input area with size 2/3 of the input video:
4156 crop=2/3*in_w:2/3*in_h
4160 Crop the input video central square:
4167 Delimit the rectangle with the top-left corner placed at position
4168 100:100 and the right-bottom corner corresponding to the right-bottom
4169 corner of the input image.
4171 crop=in_w-100:in_h-100:100:100
4175 Crop 10 pixels from the left and right borders, and 20 pixels from
4176 the top and bottom borders
4178 crop=in_w-2*10:in_h-2*20
4182 Keep only the bottom right quarter of the input image:
4184 crop=in_w/2:in_h/2:in_w/2:in_h/2
4188 Crop height for getting Greek harmony:
4190 crop=in_w:1/PHI*in_w
4194 Apply trembling effect:
4196 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)
4200 Apply erratic camera effect depending on timestamp:
4202 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)"
4206 Set x depending on the value of y:
4208 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
4212 @subsection Commands
4214 This filter supports the following commands:
4220 Set width/height of the output video and the horizontal/vertical position
4222 The command accepts the same syntax of the corresponding option.
4224 If the specified expression is not valid, it is kept at its current
4230 Auto-detect the crop size.
4232 It calculates the necessary cropping parameters and prints the
4233 recommended parameters via the logging system. The detected dimensions
4234 correspond to the non-black area of the input video.
4236 It accepts the following parameters:
4241 Set higher black value threshold, which can be optionally specified
4242 from nothing (0) to everything (255 for 8bit based formats). An intensity
4243 value greater to the set value is considered non-black. It defaults to 24.
4244 You can also specify a value between 0.0 and 1.0 which will be scaled depending
4245 on the bitdepth of the pixel format.
4248 The value which the width/height should be divisible by. It defaults to
4249 16. The offset is automatically adjusted to center the video. Use 2 to
4250 get only even dimensions (needed for 4:2:2 video). 16 is best when
4251 encoding to most video codecs.
4253 @item reset_count, reset
4254 Set the counter that determines after how many frames cropdetect will
4255 reset the previously detected largest video area and start over to
4256 detect the current optimal crop area. Default value is 0.
4258 This can be useful when channel logos distort the video area. 0
4259 indicates 'never reset', and returns the largest area encountered during
4266 Apply color adjustments using curves.
4268 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
4269 component (red, green and blue) has its values defined by @var{N} key points
4270 tied from each other using a smooth curve. The x-axis represents the pixel
4271 values from the input frame, and the y-axis the new pixel values to be set for
4274 By default, a component curve is defined by the two points @var{(0;0)} and
4275 @var{(1;1)}. This creates a straight line where each original pixel value is
4276 "adjusted" to its own value, which means no change to the image.
4278 The filter allows you to redefine these two points and add some more. A new
4279 curve (using a natural cubic spline interpolation) will be define to pass
4280 smoothly through all these new coordinates. The new defined points needs to be
4281 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
4282 be in the @var{[0;1]} interval. If the computed curves happened to go outside
4283 the vector spaces, the values will be clipped accordingly.
4285 If there is no key point defined in @code{x=0}, the filter will automatically
4286 insert a @var{(0;0)} point. In the same way, if there is no key point defined
4287 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
4289 The filter accepts the following options:
4293 Select one of the available color presets. This option can be used in addition
4294 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
4295 options takes priority on the preset values.
4296 Available presets are:
4299 @item color_negative
4302 @item increase_contrast
4304 @item linear_contrast
4305 @item medium_contrast
4307 @item strong_contrast
4310 Default is @code{none}.
4312 Set the master key points. These points will define a second pass mapping. It
4313 is sometimes called a "luminance" or "value" mapping. It can be used with
4314 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
4315 post-processing LUT.
4317 Set the key points for the red component.
4319 Set the key points for the green component.
4321 Set the key points for the blue component.
4323 Set the key points for all components (not including master).
4324 Can be used in addition to the other key points component
4325 options. In this case, the unset component(s) will fallback on this
4326 @option{all} setting.
4328 Specify a Photoshop curves file (@code{.acv}) to import the settings from.
4331 To avoid some filtergraph syntax conflicts, each key points list need to be
4332 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
4334 @subsection Examples
4338 Increase slightly the middle level of blue:
4340 curves=blue='0.5/0.58'
4346 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
4348 Here we obtain the following coordinates for each components:
4351 @code{(0;0.11) (0.42;0.51) (1;0.95)}
4353 @code{(0;0) (0.50;0.48) (1;1)}
4355 @code{(0;0.22) (0.49;0.44) (1;0.80)}
4359 The previous example can also be achieved with the associated built-in preset:
4361 curves=preset=vintage
4371 Use a Photoshop preset and redefine the points of the green component:
4373 curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'
4379 Denoise frames using 2D DCT (frequency domain filtering).
4381 This filter is not designed for real time.
4383 The filter accepts the following options:
4387 Set the noise sigma constant.
4389 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
4390 coefficient (absolute value) below this threshold with be dropped.
4392 If you need a more advanced filtering, see @option{expr}.
4394 Default is @code{0}.
4397 Set number overlapping pixels for each block. Since the filter can be slow, you
4398 may want to reduce this value, at the cost of a less effective filter and the
4399 risk of various artefacts.
4401 If the overlapping value doesn't permit processing the whole input width or
4402 height, a warning will be displayed and according borders won't be denoised.
4404 Default value is @var{blocksize}-1, which is the best possible setting.
4407 Set the coefficient factor expression.
4409 For each coefficient of a DCT block, this expression will be evaluated as a
4410 multiplier value for the coefficient.
4412 If this is option is set, the @option{sigma} option will be ignored.
4414 The absolute value of the coefficient can be accessed through the @var{c}
4418 Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the
4419 @var{blocksize}, which is the width and height of the processed blocks.
4421 The default value is @var{3} (8x8) and can be raised to @var{4} for a
4422 @var{blocksize} of 16x16. Note that changing this setting has huge consequences
4423 on the speed processing. Also, a larger block size does not necessarily means a
4427 @subsection Examples
4429 Apply a denoise with a @option{sigma} of @code{4.5}:
4434 The same operation can be achieved using the expression system:
4436 dctdnoiz=e='gte(c, 4.5*3)'
4439 Violent denoise using a block size of @code{16x16}:
4446 Remove banding artifacts from input video.
4447 It works by replacing banded pixels with average value of referenced pixels.
4449 The filter accepts the following options:
4456 Set banding detection threshold for each plane. Default is 0.02.
4457 Valid range is 0.00003 to 0.5.
4458 If difference between current pixel and reference pixel is less than threshold,
4459 it will be considered as banded.
4462 Banding detection range in pixels. Default is 16. If positive, random number
4463 in range 0 to set value will be used. If negative, exact absolute value
4465 The range defines square of four pixels around current pixel.
4468 Set direction in radians from which four pixel will be compared. If positive,
4469 random direction from 0 to set direction will be picked. If negative, exact of
4470 absolute value will be picked. For example direction 0, -PI or -2*PI radians
4471 will pick only pixels on same row and -PI/2 will pick only pixels on same
4475 If enabled, current pixel is compared with average value of all four
4476 surrounding pixels. The default is enabled. If disabled current pixel is
4477 compared with all four surrounding pixels. The pixel is considered banded
4478 if only all four differences with surrounding pixels are less than threshold.
4484 Drop duplicated frames at regular intervals.
4486 The filter accepts the following options:
4490 Set the number of frames from which one will be dropped. Setting this to
4491 @var{N} means one frame in every batch of @var{N} frames will be dropped.
4492 Default is @code{5}.
4495 Set the threshold for duplicate detection. If the difference metric for a frame
4496 is less than or equal to this value, then it is declared as duplicate. Default
4500 Set scene change threshold. Default is @code{15}.
4504 Set the size of the x and y-axis blocks used during metric calculations.
4505 Larger blocks give better noise suppression, but also give worse detection of
4506 small movements. Must be a power of two. Default is @code{32}.
4509 Mark main input as a pre-processed input and activate clean source input
4510 stream. This allows the input to be pre-processed with various filters to help
4511 the metrics calculation while keeping the frame selection lossless. When set to
4512 @code{1}, the first stream is for the pre-processed input, and the second
4513 stream is the clean source from where the kept frames are chosen. Default is
4517 Set whether or not chroma is considered in the metric calculations. Default is
4523 Apply deflate effect to the video.
4525 This filter replaces the pixel by the local(3x3) average by taking into account
4526 only values lower than the pixel.
4528 It accepts the following options:
4535 Allows to limit the maximum change for each plane, default is 65535.
4536 If 0, plane will remain unchanged.
4541 Remove judder produced by partially interlaced telecined content.
4543 Judder can be introduced, for instance, by @ref{pullup} filter. If the original
4544 source was partially telecined content then the output of @code{pullup,dejudder}
4545 will have a variable frame rate. May change the recorded frame rate of the
4546 container. Aside from that change, this filter will not affect constant frame
4549 The option available in this filter is:
4553 Specify the length of the window over which the judder repeats.
4555 Accepts any integer greater than 1. Useful values are:
4559 If the original was telecined from 24 to 30 fps (Film to NTSC).
4562 If the original was telecined from 25 to 30 fps (PAL to NTSC).
4565 If a mixture of the two.
4568 The default is @samp{4}.
4573 Suppress a TV station logo by a simple interpolation of the surrounding
4574 pixels. Just set a rectangle covering the logo and watch it disappear
4575 (and sometimes something even uglier appear - your mileage may vary).
4577 It accepts the following parameters:
4582 Specify the top left corner coordinates of the logo. They must be
4587 Specify the width and height of the logo to clear. They must be
4591 Specify the thickness of the fuzzy edge of the rectangle (added to
4592 @var{w} and @var{h}). The default value is 4.
4595 When set to 1, a green rectangle is drawn on the screen to simplify
4596 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
4597 The default value is 0.
4599 The rectangle is drawn on the outermost pixels which will be (partly)
4600 replaced with interpolated values. The values of the next pixels
4601 immediately outside this rectangle in each direction will be used to
4602 compute the interpolated pixel values inside the rectangle.
4606 @subsection Examples
4610 Set a rectangle covering the area with top left corner coordinates 0,0
4611 and size 100x77, and a band of size 10:
4613 delogo=x=0:y=0:w=100:h=77:band=10
4620 Attempt to fix small changes in horizontal and/or vertical shift. This
4621 filter helps remove camera shake from hand-holding a camera, bumping a
4622 tripod, moving on a vehicle, etc.
4624 The filter accepts the following options:
4632 Specify a rectangular area where to limit the search for motion
4634 If desired the search for motion vectors can be limited to a
4635 rectangular area of the frame defined by its top left corner, width
4636 and height. These parameters have the same meaning as the drawbox
4637 filter which can be used to visualise the position of the bounding
4640 This is useful when simultaneous movement of subjects within the frame
4641 might be confused for camera motion by the motion vector search.
4643 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
4644 then the full frame is used. This allows later options to be set
4645 without specifying the bounding box for the motion vector search.
4647 Default - search the whole frame.
4651 Specify the maximum extent of movement in x and y directions in the
4652 range 0-64 pixels. Default 16.
4655 Specify how to generate pixels to fill blanks at the edge of the
4656 frame. Available values are:
4659 Fill zeroes at blank locations
4661 Original image at blank locations
4663 Extruded edge value at blank locations
4665 Mirrored edge at blank locations
4667 Default value is @samp{mirror}.
4670 Specify the blocksize to use for motion search. Range 4-128 pixels,
4674 Specify the contrast threshold for blocks. Only blocks with more than
4675 the specified contrast (difference between darkest and lightest
4676 pixels) will be considered. Range 1-255, default 125.
4679 Specify the search strategy. Available values are:
4682 Set exhaustive search
4684 Set less exhaustive search.
4686 Default value is @samp{exhaustive}.
4689 If set then a detailed log of the motion search is written to the
4693 If set to 1, specify using OpenCL capabilities, only available if
4694 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
4700 Apply an exact inverse of the telecine operation. It requires a predefined
4701 pattern specified using the pattern option which must be the same as that passed
4702 to the telecine filter.
4704 This filter accepts the following options:
4713 The default value is @code{top}.
4717 A string of numbers representing the pulldown pattern you wish to apply.
4718 The default value is @code{23}.
4721 A number representing position of the first frame with respect to the telecine
4722 pattern. This is to be used if the stream is cut. The default value is @code{0}.
4727 Apply dilation effect to the video.
4729 This filter replaces the pixel by the local(3x3) maximum.
4731 It accepts the following options:
4738 Allows to limit the maximum change for each plane, default is 65535.
4739 If 0, plane will remain unchanged.
4742 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
4745 Flags to local 3x3 coordinates maps like this:
4754 Draw a colored box on the input image.
4756 It accepts the following parameters:
4761 The expressions which specify the top left corner coordinates of the box. It defaults to 0.
4765 The expressions which specify the width and height of the box; if 0 they are interpreted as
4766 the input width and height. It defaults to 0.
4769 Specify the color of the box to write. For the general syntax of this option,
4770 check the "Color" section in the ffmpeg-utils manual. If the special
4771 value @code{invert} is used, the box edge color is the same as the
4772 video with inverted luma.
4775 The expression which sets the thickness of the box edge. Default value is @code{3}.
4777 See below for the list of accepted constants.
4780 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4781 following constants:
4785 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4789 horizontal and vertical chroma subsample values. For example for the
4790 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4794 The input width and height.
4797 The input sample aspect ratio.
4801 The x and y offset coordinates where the box is drawn.
4805 The width and height of the drawn box.
4808 The thickness of the drawn box.
4810 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
4811 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
4815 @subsection Examples
4819 Draw a black box around the edge of the input image:
4825 Draw a box with color red and an opacity of 50%:
4827 drawbox=10:20:200:60:red@@0.5
4830 The previous example can be specified as:
4832 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
4836 Fill the box with pink color:
4838 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
4842 Draw a 2-pixel red 2.40:1 mask:
4844 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
4848 @section drawgraph, adrawgraph
4850 Draw a graph using input video or audio metadata.
4852 It accepts the following parameters:
4856 Set 1st frame metadata key from which metadata values will be used to draw a graph.
4859 Set 1st foreground color expression.
4862 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
4865 Set 2nd foreground color expression.
4868 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
4871 Set 3rd foreground color expression.
4874 Set 4th frame metadata key from which metadata values will be used to draw a graph.
4877 Set 4th foreground color expression.
4880 Set minimal value of metadata value.
4883 Set maximal value of metadata value.
4886 Set graph background color. Default is white.
4891 Available values for mode is:
4898 Default is @code{line}.
4903 Available values for slide is:
4906 Draw new frame when right border is reached.
4909 Replace old columns with new ones.
4912 Scroll from right to left.
4915 Scroll from left to right.
4918 Default is @code{frame}.
4921 Set size of graph video. For the syntax of this option, check the
4922 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
4923 The default value is @code{900x256}.
4925 The foreground color expressions can use the following variables:
4928 Minimal value of metadata value.
4931 Maximal value of metadata value.
4934 Current metadata key value.
4937 The color is defined as 0xAABBGGRR.
4940 Example using metadata from @ref{signalstats} filter:
4942 signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
4945 Example using metadata from @ref{ebur128} filter:
4947 ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
4952 Draw a grid on the input image.
4954 It accepts the following parameters:
4959 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
4963 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
4964 input width and height, respectively, minus @code{thickness}, so image gets
4965 framed. Default to 0.
4968 Specify the color of the grid. For the general syntax of this option,
4969 check the "Color" section in the ffmpeg-utils manual. If the special
4970 value @code{invert} is used, the grid color is the same as the
4971 video with inverted luma.
4974 The expression which sets the thickness of the grid line. Default value is @code{1}.
4976 See below for the list of accepted constants.
4979 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4980 following constants:
4984 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4988 horizontal and vertical chroma subsample values. For example for the
4989 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4993 The input grid cell width and height.
4996 The input sample aspect ratio.
5000 The x and y coordinates of some point of grid intersection (meant to configure offset).
5004 The width and height of the drawn cell.
5007 The thickness of the drawn cell.
5009 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
5010 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
5014 @subsection Examples
5018 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
5020 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
5024 Draw a white 3x3 grid with an opacity of 50%:
5026 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
5033 Draw a text string or text from a specified file on top of a video, using the
5034 libfreetype library.
5036 To enable compilation of this filter, you need to configure FFmpeg with
5037 @code{--enable-libfreetype}.
5038 To enable default font fallback and the @var{font} option you need to
5039 configure FFmpeg with @code{--enable-libfontconfig}.
5040 To enable the @var{text_shaping} option, you need to configure FFmpeg with
5041 @code{--enable-libfribidi}.
5045 It accepts the following parameters:
5050 Used to draw a box around text using the background color.
5051 The value must be either 1 (enable) or 0 (disable).
5052 The default value of @var{box} is 0.
5055 Set the width of the border to be drawn around the box using @var{boxcolor}.
5056 The default value of @var{boxborderw} is 0.
5059 The color to be used for drawing box around text. For the syntax of this
5060 option, check the "Color" section in the ffmpeg-utils manual.
5062 The default value of @var{boxcolor} is "white".
5065 Set the width of the border to be drawn around the text using @var{bordercolor}.
5066 The default value of @var{borderw} is 0.
5069 Set the color to be used for drawing border around text. For the syntax of this
5070 option, check the "Color" section in the ffmpeg-utils manual.
5072 The default value of @var{bordercolor} is "black".
5075 Select how the @var{text} is expanded. Can be either @code{none},
5076 @code{strftime} (deprecated) or
5077 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
5081 If true, check and fix text coords to avoid clipping.
5084 The color to be used for drawing fonts. For the syntax of this option, check
5085 the "Color" section in the ffmpeg-utils manual.
5087 The default value of @var{fontcolor} is "black".
5089 @item fontcolor_expr
5090 String which is expanded the same way as @var{text} to obtain dynamic
5091 @var{fontcolor} value. By default this option has empty value and is not
5092 processed. When this option is set, it overrides @var{fontcolor} option.
5095 The font family to be used for drawing text. By default Sans.
5098 The font file to be used for drawing text. The path must be included.
5099 This parameter is mandatory if the fontconfig support is disabled.
5102 This option does not exist, please see the timeline system
5105 Draw the text applying alpha blending. The value can
5106 be either a number between 0.0 and 1.0
5107 The expression accepts the same variables @var{x, y} do.
5108 The default value is 1.
5109 Please see fontcolor_expr
5112 The font size to be used for drawing text.
5113 The default value of @var{fontsize} is 16.
5116 If set to 1, attempt to shape the text (for example, reverse the order of
5117 right-to-left text and join Arabic characters) before drawing it.
5118 Otherwise, just draw the text exactly as given.
5119 By default 1 (if supported).
5122 The flags to be used for loading the fonts.
5124 The flags map the corresponding flags supported by libfreetype, and are
5125 a combination of the following values:
5132 @item vertical_layout
5133 @item force_autohint
5136 @item ignore_global_advance_width
5138 @item ignore_transform
5144 Default value is "default".
5146 For more information consult the documentation for the FT_LOAD_*
5150 The color to be used for drawing a shadow behind the drawn text. For the
5151 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
5153 The default value of @var{shadowcolor} is "black".
5157 The x and y offsets for the text shadow position with respect to the
5158 position of the text. They can be either positive or negative
5159 values. The default value for both is "0".
5162 The starting frame number for the n/frame_num variable. The default value
5166 The size in number of spaces to use for rendering the tab.
5170 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
5171 format. It can be used with or without text parameter. @var{timecode_rate}
5172 option must be specified.
5174 @item timecode_rate, rate, r
5175 Set the timecode frame rate (timecode only).
5178 The text string to be drawn. The text must be a sequence of UTF-8
5180 This parameter is mandatory if no file is specified with the parameter
5184 A text file containing text to be drawn. The text must be a sequence
5185 of UTF-8 encoded characters.
5187 This parameter is mandatory if no text string is specified with the
5188 parameter @var{text}.
5190 If both @var{text} and @var{textfile} are specified, an error is thrown.
5193 If set to 1, the @var{textfile} will be reloaded before each frame.
5194 Be sure to update it atomically, or it may be read partially, or even fail.
5198 The expressions which specify the offsets where text will be drawn
5199 within the video frame. They are relative to the top/left border of the
5202 The default value of @var{x} and @var{y} is "0".
5204 See below for the list of accepted constants and functions.
5207 The parameters for @var{x} and @var{y} are expressions containing the
5208 following constants and functions:
5212 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
5216 horizontal and vertical chroma subsample values. For example for the
5217 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5220 the height of each text line
5228 @item max_glyph_a, ascent
5229 the maximum distance from the baseline to the highest/upper grid
5230 coordinate used to place a glyph outline point, for all the rendered
5232 It is a positive value, due to the grid's orientation with the Y axis
5235 @item max_glyph_d, descent
5236 the maximum distance from the baseline to the lowest grid coordinate
5237 used to place a glyph outline point, for all the rendered glyphs.
5238 This is a negative value, due to the grid's orientation, with the Y axis
5242 maximum glyph height, that is the maximum height for all the glyphs
5243 contained in the rendered text, it is equivalent to @var{ascent} -
5247 maximum glyph width, that is the maximum width for all the glyphs
5248 contained in the rendered text
5251 the number of input frame, starting from 0
5253 @item rand(min, max)
5254 return a random number included between @var{min} and @var{max}
5257 The input sample aspect ratio.
5260 timestamp expressed in seconds, NAN if the input timestamp is unknown
5263 the height of the rendered text
5266 the width of the rendered text
5270 the x and y offset coordinates where the text is drawn.
5272 These parameters allow the @var{x} and @var{y} expressions to refer
5273 each other, so you can for example specify @code{y=x/dar}.
5276 @anchor{drawtext_expansion}
5277 @subsection Text expansion
5279 If @option{expansion} is set to @code{strftime},
5280 the filter recognizes strftime() sequences in the provided text and
5281 expands them accordingly. Check the documentation of strftime(). This
5282 feature is deprecated.
5284 If @option{expansion} is set to @code{none}, the text is printed verbatim.
5286 If @option{expansion} is set to @code{normal} (which is the default),
5287 the following expansion mechanism is used.
5289 The backslash character @samp{\}, followed by any character, always expands to
5290 the second character.
5292 Sequence of the form @code{%@{...@}} are expanded. The text between the
5293 braces is a function name, possibly followed by arguments separated by ':'.
5294 If the arguments contain special characters or delimiters (':' or '@}'),
5295 they should be escaped.
5297 Note that they probably must also be escaped as the value for the
5298 @option{text} option in the filter argument string and as the filter
5299 argument in the filtergraph description, and possibly also for the shell,
5300 that makes up to four levels of escaping; using a text file avoids these
5303 The following functions are available:
5308 The expression evaluation result.
5310 It must take one argument specifying the expression to be evaluated,
5311 which accepts the same constants and functions as the @var{x} and
5312 @var{y} values. Note that not all constants should be used, for
5313 example the text size is not known when evaluating the expression, so
5314 the constants @var{text_w} and @var{text_h} will have an undefined
5317 @item expr_int_format, eif
5318 Evaluate the expression's value and output as formatted integer.
5320 The first argument is the expression to be evaluated, just as for the @var{expr} function.
5321 The second argument specifies the output format. Allowed values are @samp{x},
5322 @samp{X}, @samp{d} and @samp{u}. They are treated exactly as in the
5323 @code{printf} function.
5324 The third parameter is optional and sets the number of positions taken by the output.
5325 It can be used to add padding with zeros from the left.
5328 The time at which the filter is running, expressed in UTC.
5329 It can accept an argument: a strftime() format string.
5332 The time at which the filter is running, expressed in the local time zone.
5333 It can accept an argument: a strftime() format string.
5336 Frame metadata. It must take one argument specifying metadata key.
5339 The frame number, starting from 0.
5342 A 1 character description of the current picture type.
5345 The timestamp of the current frame.
5346 It can take up to two arguments.
5348 The first argument is the format of the timestamp; it defaults to @code{flt}
5349 for seconds as a decimal number with microsecond accuracy; @code{hms} stands
5350 for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy.
5352 The second argument is an offset added to the timestamp.
5356 @subsection Examples
5360 Draw "Test Text" with font FreeSerif, using the default values for the
5361 optional parameters.
5364 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
5368 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
5369 and y=50 (counting from the top-left corner of the screen), text is
5370 yellow with a red box around it. Both the text and the box have an
5374 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
5375 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
5378 Note that the double quotes are not necessary if spaces are not used
5379 within the parameter list.
5382 Show the text at the center of the video frame:
5384 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
5388 Show a text line sliding from right to left in the last row of the video
5389 frame. The file @file{LONG_LINE} is assumed to contain a single line
5392 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
5396 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
5398 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
5402 Draw a single green letter "g", at the center of the input video.
5403 The glyph baseline is placed at half screen height.
5405 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
5409 Show text for 1 second every 3 seconds:
5411 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
5415 Use fontconfig to set the font. Note that the colons need to be escaped.
5417 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
5421 Print the date of a real-time encoding (see strftime(3)):
5423 drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}'
5427 Show text fading in and out (appearing/disappearing):
5430 DS=1.0 # display start
5431 DE=10.0 # display end
5432 FID=1.5 # fade in duration
5433 FOD=5 # fade out duration
5434 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 @}"
5439 For more information about libfreetype, check:
5440 @url{http://www.freetype.org/}.
5442 For more information about fontconfig, check:
5443 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
5445 For more information about libfribidi, check:
5446 @url{http://fribidi.org/}.
5450 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
5452 The filter accepts the following options:
5457 Set low and high threshold values used by the Canny thresholding
5460 The high threshold selects the "strong" edge pixels, which are then
5461 connected through 8-connectivity with the "weak" edge pixels selected
5462 by the low threshold.
5464 @var{low} and @var{high} threshold values must be chosen in the range
5465 [0,1], and @var{low} should be lesser or equal to @var{high}.
5467 Default value for @var{low} is @code{20/255}, and default value for @var{high}
5471 Define the drawing mode.
5475 Draw white/gray wires on black background.
5478 Mix the colors to create a paint/cartoon effect.
5481 Default value is @var{wires}.
5484 @subsection Examples
5488 Standard edge detection with custom values for the hysteresis thresholding:
5490 edgedetect=low=0.1:high=0.4
5494 Painting effect without thresholding:
5496 edgedetect=mode=colormix:high=0
5501 Set brightness, contrast, saturation and approximate gamma adjustment.
5503 The filter accepts the following options:
5507 Set the contrast expression. The value must be a float value in range
5508 @code{-2.0} to @code{2.0}. The default value is "1".
5511 Set the brightness expression. The value must be a float value in
5512 range @code{-1.0} to @code{1.0}. The default value is "0".
5515 Set the saturation expression. The value must be a float in
5516 range @code{0.0} to @code{3.0}. The default value is "1".
5519 Set the gamma expression. The value must be a float in range
5520 @code{0.1} to @code{10.0}. The default value is "1".
5523 Set the gamma expression for red. The value must be a float in
5524 range @code{0.1} to @code{10.0}. The default value is "1".
5527 Set the gamma expression for green. The value must be a float in range
5528 @code{0.1} to @code{10.0}. The default value is "1".
5531 Set the gamma expression for blue. The value must be a float in range
5532 @code{0.1} to @code{10.0}. The default value is "1".
5535 Set the gamma weight expression. It can be used to reduce the effect
5536 of a high gamma value on bright image areas, e.g. keep them from
5537 getting overamplified and just plain white. The value must be a float
5538 in range @code{0.0} to @code{1.0}. A value of @code{0.0} turns the
5539 gamma correction all the way down while @code{1.0} leaves it at its
5540 full strength. Default is "1".
5543 Set when the expressions for brightness, contrast, saturation and
5544 gamma expressions are evaluated.
5546 It accepts the following values:
5549 only evaluate expressions once during the filter initialization or
5550 when a command is processed
5553 evaluate expressions for each incoming frame
5556 Default value is @samp{init}.
5559 The expressions accept the following parameters:
5562 frame count of the input frame starting from 0
5565 byte position of the corresponding packet in the input file, NAN if
5569 frame rate of the input video, NAN if the input frame rate is unknown
5572 timestamp expressed in seconds, NAN if the input timestamp is unknown
5575 @subsection Commands
5576 The filter supports the following commands:
5580 Set the contrast expression.
5583 Set the brightness expression.
5586 Set the saturation expression.
5589 Set the gamma expression.
5592 Set the gamma_r expression.
5595 Set gamma_g expression.
5598 Set gamma_b expression.
5601 Set gamma_weight expression.
5603 The command accepts the same syntax of the corresponding option.
5605 If the specified expression is not valid, it is kept at its current
5612 Apply erosion effect to the video.
5614 This filter replaces the pixel by the local(3x3) minimum.
5616 It accepts the following options:
5623 Allows to limit the maximum change for each plane, default is 65535.
5624 If 0, plane will remain unchanged.
5627 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
5630 Flags to local 3x3 coordinates maps like this:
5637 @section extractplanes
5639 Extract color channel components from input video stream into
5640 separate grayscale video streams.
5642 The filter accepts the following option:
5646 Set plane(s) to extract.
5648 Available values for planes are:
5659 Choosing planes not available in the input will result in an error.
5660 That means you cannot select @code{r}, @code{g}, @code{b} planes
5661 with @code{y}, @code{u}, @code{v} planes at same time.
5664 @subsection Examples
5668 Extract luma, u and v color channel component from input video frame
5669 into 3 grayscale outputs:
5671 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
5677 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
5679 For each input image, the filter will compute the optimal mapping from
5680 the input to the output given the codebook length, that is the number
5681 of distinct output colors.
5683 This filter accepts the following options.
5686 @item codebook_length, l
5687 Set codebook length. The value must be a positive integer, and
5688 represents the number of distinct output colors. Default value is 256.
5691 Set the maximum number of iterations to apply for computing the optimal
5692 mapping. The higher the value the better the result and the higher the
5693 computation time. Default value is 1.
5696 Set a random seed, must be an integer included between 0 and
5697 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
5698 will try to use a good random seed on a best effort basis.
5701 Set pal8 output pixel format. This option does not work with codebook
5702 length greater than 256.
5707 Apply a fade-in/out effect to the input video.
5709 It accepts the following parameters:
5713 The effect type can be either "in" for a fade-in, or "out" for a fade-out
5715 Default is @code{in}.
5717 @item start_frame, s
5718 Specify the number of the frame to start applying the fade
5719 effect at. Default is 0.
5722 The number of frames that the fade effect lasts. At the end of the
5723 fade-in effect, the output video will have the same intensity as the input video.
5724 At the end of the fade-out transition, the output video will be filled with the
5725 selected @option{color}.
5729 If set to 1, fade only alpha channel, if one exists on the input.
5732 @item start_time, st
5733 Specify the timestamp (in seconds) of the frame to start to apply the fade
5734 effect. If both start_frame and start_time are specified, the fade will start at
5735 whichever comes last. Default is 0.
5738 The number of seconds for which the fade effect has to last. At the end of the
5739 fade-in effect the output video will have the same intensity as the input video,
5740 at the end of the fade-out transition the output video will be filled with the
5741 selected @option{color}.
5742 If both duration and nb_frames are specified, duration is used. Default is 0
5743 (nb_frames is used by default).
5746 Specify the color of the fade. Default is "black".
5749 @subsection Examples
5753 Fade in the first 30 frames of video:
5758 The command above is equivalent to:
5764 Fade out the last 45 frames of a 200-frame video:
5767 fade=type=out:start_frame=155:nb_frames=45
5771 Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
5773 fade=in:0:25, fade=out:975:25
5777 Make the first 5 frames yellow, then fade in from frame 5-24:
5779 fade=in:5:20:color=yellow
5783 Fade in alpha over first 25 frames of video:
5785 fade=in:0:25:alpha=1
5789 Make the first 5.5 seconds black, then fade in for 0.5 seconds:
5791 fade=t=in:st=5.5:d=0.5
5797 Apply arbitrary expressions to samples in frequency domain
5801 Adjust the dc value (gain) of the luma plane of the image. The filter
5802 accepts an integer value in range @code{0} to @code{1000}. The default
5803 value is set to @code{0}.
5806 Adjust the dc value (gain) of the 1st chroma plane of the image. The
5807 filter accepts an integer value in range @code{0} to @code{1000}. The
5808 default value is set to @code{0}.
5811 Adjust the dc value (gain) of the 2nd chroma plane of the image. The
5812 filter accepts an integer value in range @code{0} to @code{1000}. The
5813 default value is set to @code{0}.
5816 Set the frequency domain weight expression for the luma plane.
5819 Set the frequency domain weight expression for the 1st chroma plane.
5822 Set the frequency domain weight expression for the 2nd chroma plane.
5824 The filter accepts the following variables:
5827 The coordinates of the current sample.
5831 The width and height of the image.
5834 @subsection Examples
5840 fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
5846 fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
5852 fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
5859 Extract a single field from an interlaced image using stride
5860 arithmetic to avoid wasting CPU time. The output frames are marked as
5863 The filter accepts the following options:
5867 Specify whether to extract the top (if the value is @code{0} or
5868 @code{top}) or the bottom field (if the value is @code{1} or
5874 Field matching filter for inverse telecine. It is meant to reconstruct the
5875 progressive frames from a telecined stream. The filter does not drop duplicated
5876 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
5877 followed by a decimation filter such as @ref{decimate} in the filtergraph.
5879 The separation of the field matching and the decimation is notably motivated by
5880 the possibility of inserting a de-interlacing filter fallback between the two.
5881 If the source has mixed telecined and real interlaced content,
5882 @code{fieldmatch} will not be able to match fields for the interlaced parts.
5883 But these remaining combed frames will be marked as interlaced, and thus can be
5884 de-interlaced by a later filter such as @ref{yadif} before decimation.
5886 In addition to the various configuration options, @code{fieldmatch} can take an
5887 optional second stream, activated through the @option{ppsrc} option. If
5888 enabled, the frames reconstruction will be based on the fields and frames from
5889 this second stream. This allows the first input to be pre-processed in order to
5890 help the various algorithms of the filter, while keeping the output lossless
5891 (assuming the fields are matched properly). Typically, a field-aware denoiser,
5892 or brightness/contrast adjustments can help.
5894 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
5895 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
5896 which @code{fieldmatch} is based on. While the semantic and usage are very
5897 close, some behaviour and options names can differ.
5899 The @ref{decimate} filter currently only works for constant frame rate input.
5900 If your input has mixed telecined (30fps) and progressive content with a lower
5901 framerate like 24fps use the following filterchain to produce the necessary cfr
5902 stream: @code{dejudder,fps=30000/1001,fieldmatch,decimate}.
5904 The filter accepts the following options:
5908 Specify the assumed field order of the input stream. Available values are:
5912 Auto detect parity (use FFmpeg's internal parity value).
5914 Assume bottom field first.
5916 Assume top field first.
5919 Note that it is sometimes recommended not to trust the parity announced by the
5922 Default value is @var{auto}.
5925 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
5926 sense that it won't risk creating jerkiness due to duplicate frames when
5927 possible, but if there are bad edits or blended fields it will end up
5928 outputting combed frames when a good match might actually exist. On the other
5929 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
5930 but will almost always find a good frame if there is one. The other values are
5931 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
5932 jerkiness and creating duplicate frames versus finding good matches in sections
5933 with bad edits, orphaned fields, blended fields, etc.
5935 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
5937 Available values are:
5941 2-way matching (p/c)
5943 2-way matching, and trying 3rd match if still combed (p/c + n)
5945 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
5947 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
5948 still combed (p/c + n + u/b)
5950 3-way matching (p/c/n)
5952 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
5953 detected as combed (p/c/n + u/b)
5956 The parenthesis at the end indicate the matches that would be used for that
5957 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
5960 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
5963 Default value is @var{pc_n}.
5966 Mark the main input stream as a pre-processed input, and enable the secondary
5967 input stream as the clean source to pick the fields from. See the filter
5968 introduction for more details. It is similar to the @option{clip2} feature from
5971 Default value is @code{0} (disabled).
5974 Set the field to match from. It is recommended to set this to the same value as
5975 @option{order} unless you experience matching failures with that setting. In
5976 certain circumstances changing the field that is used to match from can have a
5977 large impact on matching performance. Available values are:
5981 Automatic (same value as @option{order}).
5983 Match from the bottom field.
5985 Match from the top field.
5988 Default value is @var{auto}.
5991 Set whether or not chroma is included during the match comparisons. In most
5992 cases it is recommended to leave this enabled. You should set this to @code{0}
5993 only if your clip has bad chroma problems such as heavy rainbowing or other
5994 artifacts. Setting this to @code{0} could also be used to speed things up at
5995 the cost of some accuracy.
5997 Default value is @code{1}.
6001 These define an exclusion band which excludes the lines between @option{y0} and
6002 @option{y1} from being included in the field matching decision. An exclusion
6003 band can be used to ignore subtitles, a logo, or other things that may
6004 interfere with the matching. @option{y0} sets the starting scan line and
6005 @option{y1} sets the ending line; all lines in between @option{y0} and
6006 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
6007 @option{y0} and @option{y1} to the same value will disable the feature.
6008 @option{y0} and @option{y1} defaults to @code{0}.
6011 Set the scene change detection threshold as a percentage of maximum change on
6012 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
6013 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
6014 @option{scthresh} is @code{[0.0, 100.0]}.
6016 Default value is @code{12.0}.
6019 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
6020 account the combed scores of matches when deciding what match to use as the
6021 final match. Available values are:
6025 No final matching based on combed scores.
6027 Combed scores are only used when a scene change is detected.
6029 Use combed scores all the time.
6032 Default is @var{sc}.
6035 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
6036 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
6037 Available values are:
6041 No forced calculation.
6043 Force p/c/n calculations.
6045 Force p/c/n/u/b calculations.
6048 Default value is @var{none}.
6051 This is the area combing threshold used for combed frame detection. This
6052 essentially controls how "strong" or "visible" combing must be to be detected.
6053 Larger values mean combing must be more visible and smaller values mean combing
6054 can be less visible or strong and still be detected. Valid settings are from
6055 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
6056 be detected as combed). This is basically a pixel difference value. A good
6057 range is @code{[8, 12]}.
6059 Default value is @code{9}.
6062 Sets whether or not chroma is considered in the combed frame decision. Only
6063 disable this if your source has chroma problems (rainbowing, etc.) that are
6064 causing problems for the combed frame detection with chroma enabled. Actually,
6065 using @option{chroma}=@var{0} is usually more reliable, except for the case
6066 where there is chroma only combing in the source.
6068 Default value is @code{0}.
6072 Respectively set the x-axis and y-axis size of the window used during combed
6073 frame detection. This has to do with the size of the area in which
6074 @option{combpel} pixels are required to be detected as combed for a frame to be
6075 declared combed. See the @option{combpel} parameter description for more info.
6076 Possible values are any number that is a power of 2 starting at 4 and going up
6079 Default value is @code{16}.
6082 The number of combed pixels inside any of the @option{blocky} by
6083 @option{blockx} size blocks on the frame for the frame to be detected as
6084 combed. While @option{cthresh} controls how "visible" the combing must be, this
6085 setting controls "how much" combing there must be in any localized area (a
6086 window defined by the @option{blockx} and @option{blocky} settings) on the
6087 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
6088 which point no frames will ever be detected as combed). This setting is known
6089 as @option{MI} in TFM/VFM vocabulary.
6091 Default value is @code{80}.
6094 @anchor{p/c/n/u/b meaning}
6095 @subsection p/c/n/u/b meaning
6097 @subsubsection p/c/n
6099 We assume the following telecined stream:
6102 Top fields: 1 2 2 3 4
6103 Bottom fields: 1 2 3 4 4
6106 The numbers correspond to the progressive frame the fields relate to. Here, the
6107 first two frames are progressive, the 3rd and 4th are combed, and so on.
6109 When @code{fieldmatch} is configured to run a matching from bottom
6110 (@option{field}=@var{bottom}) this is how this input stream get transformed:
6115 B 1 2 3 4 4 <-- matching reference
6124 As a result of the field matching, we can see that some frames get duplicated.
6125 To perform a complete inverse telecine, you need to rely on a decimation filter
6126 after this operation. See for instance the @ref{decimate} filter.
6128 The same operation now matching from top fields (@option{field}=@var{top})
6133 T 1 2 2 3 4 <-- matching reference
6143 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
6144 basically, they refer to the frame and field of the opposite parity:
6147 @item @var{p} matches the field of the opposite parity in the previous frame
6148 @item @var{c} matches the field of the opposite parity in the current frame
6149 @item @var{n} matches the field of the opposite parity in the next frame
6154 The @var{u} and @var{b} matching are a bit special in the sense that they match
6155 from the opposite parity flag. In the following examples, we assume that we are
6156 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
6157 'x' is placed above and below each matched fields.
6159 With bottom matching (@option{field}=@var{bottom}):
6164 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6165 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6173 With top matching (@option{field}=@var{top}):
6178 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6179 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6187 @subsection Examples
6189 Simple IVTC of a top field first telecined stream:
6191 fieldmatch=order=tff:combmatch=none, decimate
6194 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
6196 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
6201 Transform the field order of the input video.
6203 It accepts the following parameters:
6208 The output field order. Valid values are @var{tff} for top field first or @var{bff}
6209 for bottom field first.
6212 The default value is @samp{tff}.
6214 The transformation is done by shifting the picture content up or down
6215 by one line, and filling the remaining line with appropriate picture content.
6216 This method is consistent with most broadcast field order converters.
6218 If the input video is not flagged as being interlaced, or it is already
6219 flagged as being of the required output field order, then this filter does
6220 not alter the incoming video.
6222 It is very useful when converting to or from PAL DV material,
6223 which is bottom field first.
6227 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
6232 Buffer input images and send them when they are requested.
6234 It is mainly useful when auto-inserted by the libavfilter
6237 It does not take parameters.
6241 Find a rectangular object
6243 It accepts the following options:
6247 Filepath of the object image, needs to be in gray8.
6250 Detection threshold, default is 0.5.
6253 Number of mipmaps, default is 3.
6255 @item xmin, ymin, xmax, ymax
6256 Specifies the rectangle in which to search.
6259 @subsection Examples
6263 Generate a representative palette of a given video using @command{ffmpeg}:
6265 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6271 Cover a rectangular object
6273 It accepts the following options:
6277 Filepath of the optional cover image, needs to be in yuv420.
6282 It accepts the following values:
6285 cover it by the supplied image
6287 cover it by interpolating the surrounding pixels
6290 Default value is @var{blur}.
6293 @subsection Examples
6297 Generate a representative palette of a given video using @command{ffmpeg}:
6299 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6306 Convert the input video to one of the specified pixel formats.
6307 Libavfilter will try to pick one that is suitable as input to
6310 It accepts the following parameters:
6314 A '|'-separated list of pixel format names, such as
6315 "pix_fmts=yuv420p|monow|rgb24".
6319 @subsection Examples
6323 Convert the input video to the @var{yuv420p} format
6325 format=pix_fmts=yuv420p
6328 Convert the input video to any of the formats in the list
6330 format=pix_fmts=yuv420p|yuv444p|yuv410p
6337 Convert the video to specified constant frame rate by duplicating or dropping
6338 frames as necessary.
6340 It accepts the following parameters:
6344 The desired output frame rate. The default is @code{25}.
6349 Possible values are:
6352 zero round towards 0
6356 round towards -infinity
6358 round towards +infinity
6362 The default is @code{near}.
6365 Assume the first PTS should be the given value, in seconds. This allows for
6366 padding/trimming at the start of stream. By default, no assumption is made
6367 about the first frame's expected PTS, so no padding or trimming is done.
6368 For example, this could be set to 0 to pad the beginning with duplicates of
6369 the first frame if a video stream starts after the audio stream or to trim any
6370 frames with a negative PTS.
6374 Alternatively, the options can be specified as a flat string:
6375 @var{fps}[:@var{round}].
6377 See also the @ref{setpts} filter.
6379 @subsection Examples
6383 A typical usage in order to set the fps to 25:
6389 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
6391 fps=fps=film:round=near
6397 Pack two different video streams into a stereoscopic video, setting proper
6398 metadata on supported codecs. The two views should have the same size and
6399 framerate and processing will stop when the shorter video ends. Please note
6400 that you may conveniently adjust view properties with the @ref{scale} and
6403 It accepts the following parameters:
6407 The desired packing format. Supported values are:
6412 The views are next to each other (default).
6415 The views are on top of each other.
6418 The views are packed by line.
6421 The views are packed by column.
6424 The views are temporally interleaved.
6433 # Convert left and right views into a frame-sequential video
6434 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
6436 # Convert views into a side-by-side video with the same output resolution as the input
6437 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
6442 Change the frame rate by interpolating new video output frames from the source
6445 This filter is not designed to function correctly with interlaced media. If
6446 you wish to change the frame rate of interlaced media then you are required
6447 to deinterlace before this filter and re-interlace after this filter.
6449 A description of the accepted options follows.
6453 Specify the output frames per second. This option can also be specified
6454 as a value alone. The default is @code{50}.
6457 Specify the start of a range where the output frame will be created as a
6458 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6459 the default is @code{15}.
6462 Specify the end of a range where the output frame will be created as a
6463 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6464 the default is @code{240}.
6467 Specify the level at which a scene change is detected as a value between
6468 0 and 100 to indicate a new scene; a low value reflects a low
6469 probability for the current frame to introduce a new scene, while a higher
6470 value means the current frame is more likely to be one.
6471 The default is @code{7}.
6474 Specify flags influencing the filter process.
6476 Available value for @var{flags} is:
6479 @item scene_change_detect, scd
6480 Enable scene change detection using the value of the option @var{scene}.
6481 This flag is enabled by default.
6487 Select one frame every N-th frame.
6489 This filter accepts the following option:
6492 Select frame after every @code{step} frames.
6493 Allowed values are positive integers higher than 0. Default value is @code{1}.
6499 Apply a frei0r effect to the input video.
6501 To enable the compilation of this filter, you need to install the frei0r
6502 header and configure FFmpeg with @code{--enable-frei0r}.
6504 It accepts the following parameters:
6509 The name of the frei0r effect to load. If the environment variable
6510 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
6511 directories specified by the colon-separated list in @env{FREIOR_PATH}.
6512 Otherwise, the standard frei0r paths are searched, in this order:
6513 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
6514 @file{/usr/lib/frei0r-1/}.
6517 A '|'-separated list of parameters to pass to the frei0r effect.
6521 A frei0r effect parameter can be a boolean (its value is either
6522 "y" or "n"), a double, a color (specified as
6523 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
6524 numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
6525 section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where
6526 @var{X} and @var{Y} are floating point numbers) and/or a string.
6528 The number and types of parameters depend on the loaded effect. If an
6529 effect parameter is not specified, the default value is set.
6531 @subsection Examples
6535 Apply the distort0r effect, setting the first two double parameters:
6537 frei0r=filter_name=distort0r:filter_params=0.5|0.01
6541 Apply the colordistance effect, taking a color as the first parameter:
6543 frei0r=colordistance:0.2/0.3/0.4
6544 frei0r=colordistance:violet
6545 frei0r=colordistance:0x112233
6549 Apply the perspective effect, specifying the top left and top right image
6552 frei0r=perspective:0.2/0.2|0.8/0.2
6556 For more information, see
6557 @url{http://frei0r.dyne.org}
6561 Apply fast and simple postprocessing. It is a faster version of @ref{spp}.
6563 It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
6564 processing filter, one of them is performed once per block, not per pixel.
6565 This allows for much higher speed.
6567 The filter accepts the following options:
6571 Set quality. This option defines the number of levels for averaging. It accepts
6572 an integer in the range 4-5. Default value is @code{4}.
6575 Force a constant quantization parameter. It accepts an integer in range 0-63.
6576 If not set, the filter will use the QP from the video stream (if available).
6579 Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
6580 more details but also more artifacts, while higher values make the image smoother
6581 but also blurrier. Default value is @code{0} − PSNR optimal.
6584 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
6585 option may cause flicker since the B-Frames have often larger QP. Default is
6586 @code{0} (not enabled).
6592 The filter accepts the following options:
6596 Set the luminance expression.
6598 Set the chrominance blue expression.
6600 Set the chrominance red expression.
6602 Set the alpha expression.
6604 Set the red expression.
6606 Set the green expression.
6608 Set the blue expression.
6611 The colorspace is selected according to the specified options. If one
6612 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
6613 options is specified, the filter will automatically select a YCbCr
6614 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
6615 @option{blue_expr} options is specified, it will select an RGB
6618 If one of the chrominance expression is not defined, it falls back on the other
6619 one. If no alpha expression is specified it will evaluate to opaque value.
6620 If none of chrominance expressions are specified, they will evaluate
6621 to the luminance expression.
6623 The expressions can use the following variables and functions:
6627 The sequential number of the filtered frame, starting from @code{0}.
6631 The coordinates of the current sample.
6635 The width and height of the image.
6639 Width and height scale depending on the currently filtered plane. It is the
6640 ratio between the corresponding luma plane number of pixels and the current
6641 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
6642 @code{0.5,0.5} for chroma planes.
6645 Time of the current frame, expressed in seconds.
6648 Return the value of the pixel at location (@var{x},@var{y}) of the current
6652 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
6656 Return the value of the pixel at location (@var{x},@var{y}) of the
6657 blue-difference chroma plane. Return 0 if there is no such plane.
6660 Return the value of the pixel at location (@var{x},@var{y}) of the
6661 red-difference chroma plane. Return 0 if there is no such plane.
6666 Return the value of the pixel at location (@var{x},@var{y}) of the
6667 red/green/blue component. Return 0 if there is no such component.
6670 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
6671 plane. Return 0 if there is no such plane.
6674 For functions, if @var{x} and @var{y} are outside the area, the value will be
6675 automatically clipped to the closer edge.
6677 @subsection Examples
6681 Flip the image horizontally:
6687 Generate a bidimensional sine wave, with angle @code{PI/3} and a
6688 wavelength of 100 pixels:
6690 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
6694 Generate a fancy enigmatic moving light:
6696 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
6700 Generate a quick emboss effect:
6702 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
6706 Modify RGB components depending on pixel position:
6708 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
6712 Create a radial gradient that is the same size as the input (also see
6713 the @ref{vignette} filter):
6715 geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
6719 Create a linear gradient to use as a mask for another filter, then
6720 compose with @ref{overlay}. In this example the video will gradually
6721 become more blurry from the top to the bottom of the y-axis as defined
6722 by the linear gradient:
6724 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
6730 Fix the banding artifacts that are sometimes introduced into nearly flat
6731 regions by truncation to 8bit color depth.
6732 Interpolate the gradients that should go where the bands are, and
6735 It is designed for playback only. Do not use it prior to
6736 lossy compression, because compression tends to lose the dither and
6737 bring back the bands.
6739 It accepts the following parameters:
6744 The maximum amount by which the filter will change any one pixel. This is also
6745 the threshold for detecting nearly flat regions. Acceptable values range from
6746 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
6750 The neighborhood to fit the gradient to. A larger radius makes for smoother
6751 gradients, but also prevents the filter from modifying the pixels near detailed
6752 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
6753 values will be clipped to the valid range.
6757 Alternatively, the options can be specified as a flat string:
6758 @var{strength}[:@var{radius}]
6760 @subsection Examples
6764 Apply the filter with a @code{3.5} strength and radius of @code{8}:
6770 Specify radius, omitting the strength (which will fall-back to the default
6781 Apply a Hald CLUT to a video stream.
6783 First input is the video stream to process, and second one is the Hald CLUT.
6784 The Hald CLUT input can be a simple picture or a complete video stream.
6786 The filter accepts the following options:
6790 Force termination when the shortest input terminates. Default is @code{0}.
6792 Continue applying the last CLUT after the end of the stream. A value of
6793 @code{0} disable the filter after the last frame of the CLUT is reached.
6794 Default is @code{1}.
6797 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
6798 filters share the same internals).
6800 More information about the Hald CLUT can be found on Eskil Steenberg's website
6801 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
6803 @subsection Workflow examples
6805 @subsubsection Hald CLUT video stream
6807 Generate an identity Hald CLUT stream altered with various effects:
6809 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
6812 Note: make sure you use a lossless codec.
6814 Then use it with @code{haldclut} to apply it on some random stream:
6816 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
6819 The Hald CLUT will be applied to the 10 first seconds (duration of
6820 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
6821 to the remaining frames of the @code{mandelbrot} stream.
6823 @subsubsection Hald CLUT with preview
6825 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
6826 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
6827 biggest possible square starting at the top left of the picture. The remaining
6828 padding pixels (bottom or right) will be ignored. This area can be used to add
6829 a preview of the Hald CLUT.
6831 Typically, the following generated Hald CLUT will be supported by the
6832 @code{haldclut} filter:
6835 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
6836 pad=iw+320 [padded_clut];
6837 smptebars=s=320x256, split [a][b];
6838 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
6839 [main][b] overlay=W-320" -frames:v 1 clut.png
6842 It contains the original and a preview of the effect of the CLUT: SMPTE color
6843 bars are displayed on the right-top, and below the same color bars processed by
6846 Then, the effect of this Hald CLUT can be visualized with:
6848 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
6853 Flip the input video horizontally.
6855 For example, to horizontally flip the input video with @command{ffmpeg}:
6857 ffmpeg -i in.avi -vf "hflip" out.avi
6861 This filter applies a global color histogram equalization on a
6864 It can be used to correct video that has a compressed range of pixel
6865 intensities. The filter redistributes the pixel intensities to
6866 equalize their distribution across the intensity range. It may be
6867 viewed as an "automatically adjusting contrast filter". This filter is
6868 useful only for correcting degraded or poorly captured source
6871 The filter accepts the following options:
6875 Determine the amount of equalization to be applied. As the strength
6876 is reduced, the distribution of pixel intensities more-and-more
6877 approaches that of the input frame. The value must be a float number
6878 in the range [0,1] and defaults to 0.200.
6881 Set the maximum intensity that can generated and scale the output
6882 values appropriately. The strength should be set as desired and then
6883 the intensity can be limited if needed to avoid washing-out. The value
6884 must be a float number in the range [0,1] and defaults to 0.210.
6887 Set the antibanding level. If enabled the filter will randomly vary
6888 the luminance of output pixels by a small amount to avoid banding of
6889 the histogram. Possible values are @code{none}, @code{weak} or
6890 @code{strong}. It defaults to @code{none}.
6895 Compute and draw a color distribution histogram for the input video.
6897 The computed histogram is a representation of the color component
6898 distribution in an image.
6900 The filter accepts the following options:
6906 It accepts the following values:
6909 Standard histogram that displays the color components distribution in an
6910 image. Displays color graph for each color component. Shows distribution of
6911 the Y, U, V, A or R, G, B components, depending on input format, in the
6912 current frame. Below each graph a color component scale meter is shown.
6915 Displays chroma values (U/V color placement) in a two dimensional
6916 graph (which is called a vectorscope). The brighter a pixel in the
6917 vectorscope, the more pixels of the input frame correspond to that pixel
6918 (i.e., more pixels have this chroma value). The V component is displayed on
6919 the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost
6920 side being V = 255. The U component is displayed on the vertical (Y) axis,
6921 with the top representing U = 0 and the bottom representing U = 255.
6923 The position of a white pixel in the graph corresponds to the chroma value of
6924 a pixel of the input clip. The graph can therefore be used to read the hue
6925 (color flavor) and the saturation (the dominance of the hue in the color). As
6926 the hue of a color changes, it moves around the square. At the center of the
6927 square the saturation is zero, which means that the corresponding pixel has no
6928 color. If the amount of a specific color is increased (while leaving the other
6929 colors unchanged) the saturation increases, and the indicator moves towards
6930 the edge of the square.
6933 Chroma values in vectorscope, similar as @code{color} but actual chroma values
6937 Per row/column color component graph. In row mode, the graph on the left side
6938 represents color component value 0 and the right side represents value = 255.
6939 In column mode, the top side represents color component value = 0 and bottom
6940 side represents value = 255.
6942 Default value is @code{levels}.
6945 Set height of level in @code{levels}. Default value is @code{200}.
6946 Allowed range is [50, 2048].
6949 Set height of color scale in @code{levels}. Default value is @code{12}.
6950 Allowed range is [0, 40].
6953 Set step for @code{waveform} mode. Smaller values are useful to find out how
6954 many values of the same luminance are distributed across input rows/columns.
6955 Default value is @code{10}. Allowed range is [1, 255].
6958 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
6959 Default is @code{row}.
6961 @item waveform_mirror
6962 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
6963 means mirrored. In mirrored mode, higher values will be represented on the left
6964 side for @code{row} mode and at the top for @code{column} mode. Default is
6965 @code{0} (unmirrored).
6968 Set display mode for @code{waveform} and @code{levels}.
6969 It accepts the following values:
6972 Display separate graph for the color components side by side in
6973 @code{row} waveform mode or one below the other in @code{column} waveform mode
6974 for @code{waveform} histogram mode. For @code{levels} histogram mode,
6975 per color component graphs are placed below each other.
6977 Using this display mode in @code{waveform} histogram mode makes it easy to
6978 spot color casts in the highlights and shadows of an image, by comparing the
6979 contours of the top and the bottom graphs of each waveform. Since whites,
6980 grays, and blacks are characterized by exactly equal amounts of red, green,
6981 and blue, neutral areas of the picture should display three waveforms of
6982 roughly equal width/height. If not, the correction is easy to perform by
6983 making level adjustments the three waveforms.
6986 Presents information identical to that in the @code{parade}, except
6987 that the graphs representing color components are superimposed directly
6990 This display mode in @code{waveform} histogram mode makes it easier to spot
6991 relative differences or similarities in overlapping areas of the color
6992 components that are supposed to be identical, such as neutral whites, grays,
6995 Default is @code{parade}.
6998 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
6999 Default is @code{linear}.
7002 Set what color components to display for mode @code{levels}.
7003 Default is @code{7}.
7006 @subsection Examples
7011 Calculate and draw histogram:
7013 ffplay -i input -vf histogram
7021 This is a high precision/quality 3d denoise filter. It aims to reduce
7022 image noise, producing smooth images and making still images really
7023 still. It should enhance compressibility.
7025 It accepts the following optional parameters:
7029 A non-negative floating point number which specifies spatial luma strength.
7032 @item chroma_spatial
7033 A non-negative floating point number which specifies spatial chroma strength.
7034 It defaults to 3.0*@var{luma_spatial}/4.0.
7037 A floating point number which specifies luma temporal strength. It defaults to
7038 6.0*@var{luma_spatial}/4.0.
7041 A floating point number which specifies chroma temporal strength. It defaults to
7042 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
7047 Apply a high-quality magnification filter designed for pixel art. This filter
7048 was originally created by Maxim Stepin.
7050 It accepts the following option:
7054 Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
7055 @code{hq3x} and @code{4} for @code{hq4x}.
7056 Default is @code{3}.
7060 Stack input videos horizontally.
7062 All streams must be of same pixel format and of same height.
7064 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
7065 to create same output.
7067 The filter accept the following option:
7071 Set number of input streams. Default is 2.
7076 Modify the hue and/or the saturation of the input.
7078 It accepts the following parameters:
7082 Specify the hue angle as a number of degrees. It accepts an expression,
7083 and defaults to "0".
7086 Specify the saturation in the [-10,10] range. It accepts an expression and
7090 Specify the hue angle as a number of radians. It accepts an
7091 expression, and defaults to "0".
7094 Specify the brightness in the [-10,10] range. It accepts an expression and
7098 @option{h} and @option{H} are mutually exclusive, and can't be
7099 specified at the same time.
7101 The @option{b}, @option{h}, @option{H} and @option{s} option values are
7102 expressions containing the following constants:
7106 frame count of the input frame starting from 0
7109 presentation timestamp of the input frame expressed in time base units
7112 frame rate of the input video, NAN if the input frame rate is unknown
7115 timestamp expressed in seconds, NAN if the input timestamp is unknown
7118 time base of the input video
7121 @subsection Examples
7125 Set the hue to 90 degrees and the saturation to 1.0:
7131 Same command but expressing the hue in radians:
7137 Rotate hue and make the saturation swing between 0
7138 and 2 over a period of 1 second:
7140 hue="H=2*PI*t: s=sin(2*PI*t)+1"
7144 Apply a 3 seconds saturation fade-in effect starting at 0:
7149 The general fade-in expression can be written as:
7151 hue="s=min(0\, max((t-START)/DURATION\, 1))"
7155 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
7157 hue="s=max(0\, min(1\, (8-t)/3))"
7160 The general fade-out expression can be written as:
7162 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
7167 @subsection Commands
7169 This filter supports the following commands:
7175 Modify the hue and/or the saturation and/or brightness of the input video.
7176 The command accepts the same syntax of the corresponding option.
7178 If the specified expression is not valid, it is kept at its current
7184 Detect video interlacing type.
7186 This filter tries to detect if the input frames as interlaced, progressive,
7187 top or bottom field first. It will also try and detect fields that are
7188 repeated between adjacent frames (a sign of telecine).
7190 Single frame detection considers only immediately adjacent frames when classifying each frame.
7191 Multiple frame detection incorporates the classification history of previous frames.
7193 The filter will log these metadata values:
7196 @item single.current_frame
7197 Detected type of current frame using single-frame detection. One of:
7198 ``tff'' (top field first), ``bff'' (bottom field first),
7199 ``progressive'', or ``undetermined''
7202 Cumulative number of frames detected as top field first using single-frame detection.
7205 Cumulative number of frames detected as top field first using multiple-frame detection.
7208 Cumulative number of frames detected as bottom field first using single-frame detection.
7210 @item multiple.current_frame
7211 Detected type of current frame using multiple-frame detection. One of:
7212 ``tff'' (top field first), ``bff'' (bottom field first),
7213 ``progressive'', or ``undetermined''
7216 Cumulative number of frames detected as bottom field first using multiple-frame detection.
7218 @item single.progressive
7219 Cumulative number of frames detected as progressive using single-frame detection.
7221 @item multiple.progressive
7222 Cumulative number of frames detected as progressive using multiple-frame detection.
7224 @item single.undetermined
7225 Cumulative number of frames that could not be classified using single-frame detection.
7227 @item multiple.undetermined
7228 Cumulative number of frames that could not be classified using multiple-frame detection.
7230 @item repeated.current_frame
7231 Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''.
7233 @item repeated.neither
7234 Cumulative number of frames with no repeated field.
7237 Cumulative number of frames with the top field repeated from the previous frame's top field.
7239 @item repeated.bottom
7240 Cumulative number of frames with the bottom field repeated from the previous frame's bottom field.
7243 The filter accepts the following options:
7247 Set interlacing threshold.
7249 Set progressive threshold.
7251 Threshold for repeated field detection.
7253 Number of frames after which a given frame's contribution to the
7254 statistics is halved (i.e., it contributes only 0.5 to it's
7255 classification). The default of 0 means that all frames seen are given
7256 full weight of 1.0 forever.
7257 @item analyze_interlaced_flag
7258 When this is not 0 then idet will use the specified number of frames to determine
7259 if the interlaced flag is accurate, it will not count undetermined frames.
7260 If the flag is found to be accurate it will be used without any further
7261 computations, if it is found to be inaccurate it will be cleared without any
7262 further computations. This allows inserting the idet filter as a low computational
7263 method to clean up the interlaced flag
7268 Deinterleave or interleave fields.
7270 This filter allows one to process interlaced images fields without
7271 deinterlacing them. Deinterleaving splits the input frame into 2
7272 fields (so called half pictures). Odd lines are moved to the top
7273 half of the output image, even lines to the bottom half.
7274 You can process (filter) them independently and then re-interleave them.
7276 The filter accepts the following options:
7280 @item chroma_mode, c
7282 Available values for @var{luma_mode}, @var{chroma_mode} and
7283 @var{alpha_mode} are:
7289 @item deinterleave, d
7290 Deinterleave fields, placing one above the other.
7293 Interleave fields. Reverse the effect of deinterleaving.
7295 Default value is @code{none}.
7298 @item chroma_swap, cs
7299 @item alpha_swap, as
7300 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
7305 Apply inflate effect to the video.
7307 This filter replaces the pixel by the local(3x3) average by taking into account
7308 only values higher than the pixel.
7310 It accepts the following options:
7317 Allows to limit the maximum change for each plane, default is 65535.
7318 If 0, plane will remain unchanged.
7323 Simple interlacing filter from progressive contents. This interleaves upper (or
7324 lower) lines from odd frames with lower (or upper) lines from even frames,
7325 halving the frame rate and preserving image height.
7328 Original Original New Frame
7329 Frame 'j' Frame 'j+1' (tff)
7330 ========== =========== ==================
7331 Line 0 --------------------> Frame 'j' Line 0
7332 Line 1 Line 1 ----> Frame 'j+1' Line 1
7333 Line 2 ---------------------> Frame 'j' Line 2
7334 Line 3 Line 3 ----> Frame 'j+1' Line 3
7336 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
7339 It accepts the following optional parameters:
7343 This determines whether the interlaced frame is taken from the even
7344 (tff - default) or odd (bff) lines of the progressive frame.
7347 Enable (default) or disable the vertical lowpass filter to avoid twitter
7348 interlacing and reduce moire patterns.
7353 Deinterlace input video by applying Donald Graft's adaptive kernel
7354 deinterling. Work on interlaced parts of a video to produce
7357 The description of the accepted parameters follows.
7361 Set the threshold which affects the filter's tolerance when
7362 determining if a pixel line must be processed. It must be an integer
7363 in the range [0,255] and defaults to 10. A value of 0 will result in
7364 applying the process on every pixels.
7367 Paint pixels exceeding the threshold value to white if set to 1.
7371 Set the fields order. Swap fields if set to 1, leave fields alone if
7375 Enable additional sharpening if set to 1. Default is 0.
7378 Enable twoway sharpening if set to 1. Default is 0.
7381 @subsection Examples
7385 Apply default values:
7387 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
7391 Enable additional sharpening:
7397 Paint processed pixels in white:
7403 @section lenscorrection
7405 Correct radial lens distortion
7407 This filter can be used to correct for radial distortion as can result from the use
7408 of wide angle lenses, and thereby re-rectify the image. To find the right parameters
7409 one can use tools available for example as part of opencv or simply trial-and-error.
7410 To use opencv use the calibration sample (under samples/cpp) from the opencv sources
7411 and extract the k1 and k2 coefficients from the resulting matrix.
7413 Note that effectively the same filter is available in the open-source tools Krita and
7414 Digikam from the KDE project.
7416 In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
7417 this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
7418 brightness distribution, so you may want to use both filters together in certain
7419 cases, though you will have to take care of ordering, i.e. whether vignetting should
7420 be applied before or after lens correction.
7424 The filter accepts the following options:
7428 Relative x-coordinate of the focal point of the image, and thereby the center of the
7429 distortion. This value has a range [0,1] and is expressed as fractions of the image
7432 Relative y-coordinate of the focal point of the image, and thereby the center of the
7433 distortion. This value has a range [0,1] and is expressed as fractions of the image
7436 Coefficient of the quadratic correction term. 0.5 means no correction.
7438 Coefficient of the double quadratic correction term. 0.5 means no correction.
7441 The formula that generates the correction is:
7443 @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)
7445 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
7446 distances from the focal point in the source and target images, respectively.
7451 Apply a 3D LUT to an input video.
7453 The filter accepts the following options:
7457 Set the 3D LUT file name.
7459 Currently supported formats:
7471 Select interpolation mode.
7473 Available values are:
7477 Use values from the nearest defined point.
7479 Interpolate values using the 8 points defining a cube.
7481 Interpolate values using a tetrahedron.
7485 @section lut, lutrgb, lutyuv
7487 Compute a look-up table for binding each pixel component input value
7488 to an output value, and apply it to the input video.
7490 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
7491 to an RGB input video.
7493 These filters accept the following parameters:
7496 set first pixel component expression
7498 set second pixel component expression
7500 set third pixel component expression
7502 set fourth pixel component expression, corresponds to the alpha component
7505 set red component expression
7507 set green component expression
7509 set blue component expression
7511 alpha component expression
7514 set Y/luminance component expression
7516 set U/Cb component expression
7518 set V/Cr component expression
7521 Each of them specifies the expression to use for computing the lookup table for
7522 the corresponding pixel component values.
7524 The exact component associated to each of the @var{c*} options depends on the
7527 The @var{lut} filter requires either YUV or RGB pixel formats in input,
7528 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
7530 The expressions can contain the following constants and functions:
7535 The input width and height.
7538 The input value for the pixel component.
7541 The input value, clipped to the @var{minval}-@var{maxval} range.
7544 The maximum value for the pixel component.
7547 The minimum value for the pixel component.
7550 The negated value for the pixel component value, clipped to the
7551 @var{minval}-@var{maxval} range; it corresponds to the expression
7552 "maxval-clipval+minval".
7555 The computed value in @var{val}, clipped to the
7556 @var{minval}-@var{maxval} range.
7558 @item gammaval(gamma)
7559 The computed gamma correction value of the pixel component value,
7560 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
7562 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
7566 All expressions default to "val".
7568 @subsection Examples
7574 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
7575 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
7578 The above is the same as:
7580 lutrgb="r=negval:g=negval:b=negval"
7581 lutyuv="y=negval:u=negval:v=negval"
7591 Remove chroma components, turning the video into a graytone image:
7593 lutyuv="u=128:v=128"
7597 Apply a luma burning effect:
7603 Remove green and blue components:
7609 Set a constant alpha channel value on input:
7611 format=rgba,lutrgb=a="maxval-minval/2"
7615 Correct luminance gamma by a factor of 0.5:
7617 lutyuv=y=gammaval(0.5)
7621 Discard least significant bits of luma:
7623 lutyuv=y='bitand(val, 128+64+32)'
7627 @section mergeplanes
7629 Merge color channel components from several video streams.
7631 The filter accepts up to 4 input streams, and merge selected input
7632 planes to the output video.
7634 This filter accepts the following options:
7637 Set input to output plane mapping. Default is @code{0}.
7639 The mappings is specified as a bitmap. It should be specified as a
7640 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
7641 mapping for the first plane of the output stream. 'A' sets the number of
7642 the input stream to use (from 0 to 3), and 'a' the plane number of the
7643 corresponding input to use (from 0 to 3). The rest of the mappings is
7644 similar, 'Bb' describes the mapping for the output stream second
7645 plane, 'Cc' describes the mapping for the output stream third plane and
7646 'Dd' describes the mapping for the output stream fourth plane.
7649 Set output pixel format. Default is @code{yuva444p}.
7652 @subsection Examples
7656 Merge three gray video streams of same width and height into single video stream:
7658 [a0][a1][a2]mergeplanes=0x001020:yuv444p
7662 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
7664 [a0][a1]mergeplanes=0x00010210:yuva444p
7668 Swap Y and A plane in yuva444p stream:
7670 format=yuva444p,mergeplanes=0x03010200:yuva444p
7674 Swap U and V plane in yuv420p stream:
7676 format=yuv420p,mergeplanes=0x000201:yuv420p
7680 Cast a rgb24 clip to yuv444p:
7682 format=rgb24,mergeplanes=0x000102:yuv444p
7688 Apply motion-compensation deinterlacing.
7690 It needs one field per frame as input and must thus be used together
7691 with yadif=1/3 or equivalent.
7693 This filter accepts the following options:
7696 Set the deinterlacing mode.
7698 It accepts one of the following values:
7703 use iterative motion estimation
7705 like @samp{slow}, but use multiple reference frames.
7707 Default value is @samp{fast}.
7710 Set the picture field parity assumed for the input video. It must be
7711 one of the following values:
7715 assume top field first
7717 assume bottom field first
7720 Default value is @samp{bff}.
7723 Set per-block quantization parameter (QP) used by the internal
7726 Higher values should result in a smoother motion vector field but less
7727 optimal individual vectors. Default value is 1.
7732 Drop frames that do not differ greatly from the previous frame in
7733 order to reduce frame rate.
7735 The main use of this filter is for very-low-bitrate encoding
7736 (e.g. streaming over dialup modem), but it could in theory be used for
7737 fixing movies that were inverse-telecined incorrectly.
7739 A description of the accepted options follows.
7743 Set the maximum number of consecutive frames which can be dropped (if
7744 positive), or the minimum interval between dropped frames (if
7745 negative). If the value is 0, the frame is dropped unregarding the
7746 number of previous sequentially dropped frames.
7753 Set the dropping threshold values.
7755 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
7756 represent actual pixel value differences, so a threshold of 64
7757 corresponds to 1 unit of difference for each pixel, or the same spread
7758 out differently over the block.
7760 A frame is a candidate for dropping if no 8x8 blocks differ by more
7761 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
7762 meaning the whole image) differ by more than a threshold of @option{lo}.
7764 Default value for @option{hi} is 64*12, default value for @option{lo} is
7765 64*5, and default value for @option{frac} is 0.33.
7773 It accepts an integer in input; if non-zero it negates the
7774 alpha component (if available). The default value in input is 0.
7778 Force libavfilter not to use any of the specified pixel formats for the
7779 input to the next filter.
7781 It accepts the following parameters:
7785 A '|'-separated list of pixel format names, such as
7786 apix_fmts=yuv420p|monow|rgb24".
7790 @subsection Examples
7794 Force libavfilter to use a format different from @var{yuv420p} for the
7795 input to the vflip filter:
7797 noformat=pix_fmts=yuv420p,vflip
7801 Convert the input video to any of the formats not contained in the list:
7803 noformat=yuv420p|yuv444p|yuv410p
7809 Add noise on video input frame.
7811 The filter accepts the following options:
7819 Set noise seed for specific pixel component or all pixel components in case
7820 of @var{all_seed}. Default value is @code{123457}.
7822 @item all_strength, alls
7823 @item c0_strength, c0s
7824 @item c1_strength, c1s
7825 @item c2_strength, c2s
7826 @item c3_strength, c3s
7827 Set noise strength for specific pixel component or all pixel components in case
7828 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
7830 @item all_flags, allf
7835 Set pixel component flags or set flags for all components if @var{all_flags}.
7836 Available values for component flags are:
7839 averaged temporal noise (smoother)
7841 mix random noise with a (semi)regular pattern
7843 temporal noise (noise pattern changes between frames)
7845 uniform noise (gaussian otherwise)
7849 @subsection Examples
7851 Add temporal and uniform noise to input video:
7853 noise=alls=20:allf=t+u
7858 Pass the video source unchanged to the output.
7861 Optical Character Recognition
7863 This filter uses Tesseract for optical character recognition.
7865 It accepts the following options:
7869 Set datapath to tesseract data. Default is to use whatever was
7870 set at installation.
7873 Set language, default is "eng".
7876 Set character whitelist.
7879 Set character blacklist.
7882 The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
7886 Apply a video transform using libopencv.
7888 To enable this filter, install the libopencv library and headers and
7889 configure FFmpeg with @code{--enable-libopencv}.
7891 It accepts the following parameters:
7896 The name of the libopencv filter to apply.
7899 The parameters to pass to the libopencv filter. If not specified, the default
7904 Refer to the official libopencv documentation for more precise
7906 @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html}
7908 Several libopencv filters are supported; see the following subsections.
7913 Dilate an image by using a specific structuring element.
7914 It corresponds to the libopencv function @code{cvDilate}.
7916 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
7918 @var{struct_el} represents a structuring element, and has the syntax:
7919 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
7921 @var{cols} and @var{rows} represent the number of columns and rows of
7922 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
7923 point, and @var{shape} the shape for the structuring element. @var{shape}
7924 must be "rect", "cross", "ellipse", or "custom".
7926 If the value for @var{shape} is "custom", it must be followed by a
7927 string of the form "=@var{filename}". The file with name
7928 @var{filename} is assumed to represent a binary image, with each
7929 printable character corresponding to a bright pixel. When a custom
7930 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
7931 or columns and rows of the read file are assumed instead.
7933 The default value for @var{struct_el} is "3x3+0x0/rect".
7935 @var{nb_iterations} specifies the number of times the transform is
7936 applied to the image, and defaults to 1.
7940 # Use the default values
7943 # Dilate using a structuring element with a 5x5 cross, iterating two times
7944 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
7946 # Read the shape from the file diamond.shape, iterating two times.
7947 # The file diamond.shape may contain a pattern of characters like this
7953 # The specified columns and rows are ignored
7954 # but the anchor point coordinates are not
7955 ocv=dilate:0x0+2x2/custom=diamond.shape|2
7960 Erode an image by using a specific structuring element.
7961 It corresponds to the libopencv function @code{cvErode}.
7963 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
7964 with the same syntax and semantics as the @ref{dilate} filter.
7968 Smooth the input video.
7970 The filter takes the following parameters:
7971 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
7973 @var{type} is the type of smooth filter to apply, and must be one of
7974 the following values: "blur", "blur_no_scale", "median", "gaussian",
7975 or "bilateral". The default value is "gaussian".
7977 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
7978 depend on the smooth type. @var{param1} and
7979 @var{param2} accept integer positive values or 0. @var{param3} and
7980 @var{param4} accept floating point values.
7982 The default value for @var{param1} is 3. The default value for the
7983 other parameters is 0.
7985 These parameters correspond to the parameters assigned to the
7986 libopencv function @code{cvSmooth}.
7991 Overlay one video on top of another.
7993 It takes two inputs and has one output. The first input is the "main"
7994 video on which the second input is overlaid.
7996 It accepts the following parameters:
7998 A description of the accepted options follows.
8003 Set the expression for the x and y coordinates of the overlaid video
8004 on the main video. Default value is "0" for both expressions. In case
8005 the expression is invalid, it is set to a huge value (meaning that the
8006 overlay will not be displayed within the output visible area).
8009 The action to take when EOF is encountered on the secondary input; it accepts
8010 one of the following values:
8014 Repeat the last frame (the default).
8018 Pass the main input through.
8022 Set when the expressions for @option{x}, and @option{y} are evaluated.
8024 It accepts the following values:
8027 only evaluate expressions once during the filter initialization or
8028 when a command is processed
8031 evaluate expressions for each incoming frame
8034 Default value is @samp{frame}.
8037 If set to 1, force the output to terminate when the shortest input
8038 terminates. Default value is 0.
8041 Set the format for the output video.
8043 It accepts the following values:
8058 Default value is @samp{yuv420}.
8060 @item rgb @emph{(deprecated)}
8061 If set to 1, force the filter to accept inputs in the RGB
8062 color space. Default value is 0. This option is deprecated, use
8063 @option{format} instead.
8066 If set to 1, force the filter to draw the last overlay frame over the
8067 main input until the end of the stream. A value of 0 disables this
8068 behavior. Default value is 1.
8071 The @option{x}, and @option{y} expressions can contain the following
8077 The main input width and height.
8081 The overlay input width and height.
8085 The computed values for @var{x} and @var{y}. They are evaluated for
8090 horizontal and vertical chroma subsample values of the output
8091 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
8095 the number of input frame, starting from 0
8098 the position in the file of the input frame, NAN if unknown
8101 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
8105 Note that the @var{n}, @var{pos}, @var{t} variables are available only
8106 when evaluation is done @emph{per frame}, and will evaluate to NAN
8107 when @option{eval} is set to @samp{init}.
8109 Be aware that frames are taken from each input video in timestamp
8110 order, hence, if their initial timestamps differ, it is a good idea
8111 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
8112 have them begin in the same zero timestamp, as the example for
8113 the @var{movie} filter does.
8115 You can chain together more overlays but you should test the
8116 efficiency of such approach.
8118 @subsection Commands
8120 This filter supports the following commands:
8124 Modify the x and y of the overlay input.
8125 The command accepts the same syntax of the corresponding option.
8127 If the specified expression is not valid, it is kept at its current
8131 @subsection Examples
8135 Draw the overlay at 10 pixels from the bottom right corner of the main
8138 overlay=main_w-overlay_w-10:main_h-overlay_h-10
8141 Using named options the example above becomes:
8143 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
8147 Insert a transparent PNG logo in the bottom left corner of the input,
8148 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
8150 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
8154 Insert 2 different transparent PNG logos (second logo on bottom
8155 right corner) using the @command{ffmpeg} tool:
8157 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
8161 Add a transparent color layer on top of the main video; @code{WxH}
8162 must specify the size of the main input to the overlay filter:
8164 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
8168 Play an original video and a filtered version (here with the deshake
8169 filter) side by side using the @command{ffplay} tool:
8171 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
8174 The above command is the same as:
8176 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
8180 Make a sliding overlay appearing from the left to the right top part of the
8181 screen starting since time 2:
8183 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
8187 Compose output by putting two input videos side to side:
8189 ffmpeg -i left.avi -i right.avi -filter_complex "
8190 nullsrc=size=200x100 [background];
8191 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
8192 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
8193 [background][left] overlay=shortest=1 [background+left];
8194 [background+left][right] overlay=shortest=1:x=100 [left+right]
8199 Mask 10-20 seconds of a video by applying the delogo filter to a section
8201 ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
8202 -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]'
8207 Chain several overlays in cascade:
8209 nullsrc=s=200x200 [bg];
8210 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
8211 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
8212 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
8213 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
8214 [in3] null, [mid2] overlay=100:100 [out0]
8221 Apply Overcomplete Wavelet denoiser.
8223 The filter accepts the following options:
8229 Larger depth values will denoise lower frequency components more, but
8230 slow down filtering.
8232 Must be an int in the range 8-16, default is @code{8}.
8234 @item luma_strength, ls
8237 Must be a double value in the range 0-1000, default is @code{1.0}.
8239 @item chroma_strength, cs
8240 Set chroma strength.
8242 Must be a double value in the range 0-1000, default is @code{1.0}.
8248 Add paddings to the input image, and place the original input at the
8249 provided @var{x}, @var{y} coordinates.
8251 It accepts the following parameters:
8256 Specify an expression for the size of the output image with the
8257 paddings added. If the value for @var{width} or @var{height} is 0, the
8258 corresponding input size is used for the output.
8260 The @var{width} expression can reference the value set by the
8261 @var{height} expression, and vice versa.
8263 The default value of @var{width} and @var{height} is 0.
8267 Specify the offsets to place the input image at within the padded area,
8268 with respect to the top/left border of the output image.
8270 The @var{x} expression can reference the value set by the @var{y}
8271 expression, and vice versa.
8273 The default value of @var{x} and @var{y} is 0.
8276 Specify the color of the padded area. For the syntax of this option,
8277 check the "Color" section in the ffmpeg-utils manual.
8279 The default value of @var{color} is "black".
8282 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
8283 options are expressions containing the following constants:
8288 The input video width and height.
8292 These are the same as @var{in_w} and @var{in_h}.
8296 The output width and height (the size of the padded area), as
8297 specified by the @var{width} and @var{height} expressions.
8301 These are the same as @var{out_w} and @var{out_h}.
8305 The x and y offsets as specified by the @var{x} and @var{y}
8306 expressions, or NAN if not yet specified.
8309 same as @var{iw} / @var{ih}
8312 input sample aspect ratio
8315 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
8319 The horizontal and vertical chroma subsample values. For example for the
8320 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
8323 @subsection Examples
8327 Add paddings with the color "violet" to the input video. The output video
8328 size is 640x480, and the top-left corner of the input video is placed at
8331 pad=640:480:0:40:violet
8334 The example above is equivalent to the following command:
8336 pad=width=640:height=480:x=0:y=40:color=violet
8340 Pad the input to get an output with dimensions increased by 3/2,
8341 and put the input video at the center of the padded area:
8343 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
8347 Pad the input to get a squared output with size equal to the maximum
8348 value between the input width and height, and put the input video at
8349 the center of the padded area:
8351 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
8355 Pad the input to get a final w/h ratio of 16:9:
8357 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
8361 In case of anamorphic video, in order to set the output display aspect
8362 correctly, it is necessary to use @var{sar} in the expression,
8363 according to the relation:
8365 (ih * X / ih) * sar = output_dar
8366 X = output_dar / sar
8369 Thus the previous example needs to be modified to:
8371 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
8375 Double the output size and put the input video in the bottom-right
8376 corner of the output padded area:
8378 pad="2*iw:2*ih:ow-iw:oh-ih"
8385 Generate one palette for a whole video stream.
8387 It accepts the following options:
8391 Set the maximum number of colors to quantize in the palette.
8392 Note: the palette will still contain 256 colors; the unused palette entries
8395 @item reserve_transparent
8396 Create a palette of 255 colors maximum and reserve the last one for
8397 transparency. Reserving the transparency color is useful for GIF optimization.
8398 If not set, the maximum of colors in the palette will be 256. You probably want
8399 to disable this option for a standalone image.
8403 Set statistics mode.
8405 It accepts the following values:
8408 Compute full frame histograms.
8410 Compute histograms only for the part that differs from previous frame. This
8411 might be relevant to give more importance to the moving part of your input if
8412 the background is static.
8415 Default value is @var{full}.
8418 The filter also exports the frame metadata @code{lavfi.color_quant_ratio}
8419 (@code{nb_color_in / nb_color_out}) which you can use to evaluate the degree of
8420 color quantization of the palette. This information is also visible at
8421 @var{info} logging level.
8423 @subsection Examples
8427 Generate a representative palette of a given video using @command{ffmpeg}:
8429 ffmpeg -i input.mkv -vf palettegen palette.png
8435 Use a palette to downsample an input video stream.
8437 The filter takes two inputs: one video stream and a palette. The palette must
8438 be a 256 pixels image.
8440 It accepts the following options:
8444 Select dithering mode. Available algorithms are:
8447 Ordered 8x8 bayer dithering (deterministic)
8449 Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
8450 Note: this dithering is sometimes considered "wrong" and is included as a
8452 @item floyd_steinberg
8453 Floyd and Steingberg dithering (error diffusion)
8455 Frankie Sierra dithering v2 (error diffusion)
8457 Frankie Sierra dithering v2 "Lite" (error diffusion)
8460 Default is @var{sierra2_4a}.
8463 When @var{bayer} dithering is selected, this option defines the scale of the
8464 pattern (how much the crosshatch pattern is visible). A low value means more
8465 visible pattern for less banding, and higher value means less visible pattern
8466 at the cost of more banding.
8468 The option must be an integer value in the range [0,5]. Default is @var{2}.
8471 If set, define the zone to process
8475 Only the changing rectangle will be reprocessed. This is similar to GIF
8476 cropping/offsetting compression mechanism. This option can be useful for speed
8477 if only a part of the image is changing, and has use cases such as limiting the
8478 scope of the error diffusal @option{dither} to the rectangle that bounds the
8479 moving scene (it leads to more deterministic output if the scene doesn't change
8480 much, and as a result less moving noise and better GIF compression).
8483 Default is @var{none}.
8486 @subsection Examples
8490 Use a palette (generated for example with @ref{palettegen}) to encode a GIF
8491 using @command{ffmpeg}:
8493 ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
8497 @section perspective
8499 Correct perspective of video not recorded perpendicular to the screen.
8501 A description of the accepted parameters follows.
8512 Set coordinates expression for top left, top right, bottom left and bottom right corners.
8513 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
8514 If the @code{sense} option is set to @code{source}, then the specified points will be sent
8515 to the corners of the destination. If the @code{sense} option is set to @code{destination},
8516 then the corners of the source will be sent to the specified coordinates.
8518 The expressions can use the following variables:
8523 the width and height of video frame.
8527 Set interpolation for perspective correction.
8529 It accepts the following values:
8535 Default value is @samp{linear}.
8538 Set interpretation of coordinate options.
8540 It accepts the following values:
8544 Send point in the source specified by the given coordinates to
8545 the corners of the destination.
8547 @item 1, destination
8549 Send the corners of the source to the point in the destination specified
8550 by the given coordinates.
8552 Default value is @samp{source}.
8558 Delay interlaced video by one field time so that the field order changes.
8560 The intended use is to fix PAL movies that have been captured with the
8561 opposite field order to the film-to-video transfer.
8563 A description of the accepted parameters follows.
8569 It accepts the following values:
8572 Capture field order top-first, transfer bottom-first.
8573 Filter will delay the bottom field.
8576 Capture field order bottom-first, transfer top-first.
8577 Filter will delay the top field.
8580 Capture and transfer with the same field order. This mode only exists
8581 for the documentation of the other options to refer to, but if you
8582 actually select it, the filter will faithfully do nothing.
8585 Capture field order determined automatically by field flags, transfer
8587 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
8588 basis using field flags. If no field information is available,
8589 then this works just like @samp{u}.
8592 Capture unknown or varying, transfer opposite.
8593 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
8594 analyzing the images and selecting the alternative that produces best
8595 match between the fields.
8598 Capture top-first, transfer unknown or varying.
8599 Filter selects among @samp{t} and @samp{p} using image analysis.
8602 Capture bottom-first, transfer unknown or varying.
8603 Filter selects among @samp{b} and @samp{p} using image analysis.
8606 Capture determined by field flags, transfer unknown or varying.
8607 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
8608 image analysis. If no field information is available, then this works just
8609 like @samp{U}. This is the default mode.
8612 Both capture and transfer unknown or varying.
8613 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
8617 @section pixdesctest
8619 Pixel format descriptor test filter, mainly useful for internal
8620 testing. The output video should be equal to the input video.
8624 format=monow, pixdesctest
8627 can be used to test the monowhite pixel format descriptor definition.
8631 Enable the specified chain of postprocessing subfilters using libpostproc. This
8632 library should be automatically selected with a GPL build (@code{--enable-gpl}).
8633 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
8634 Each subfilter and some options have a short and a long name that can be used
8635 interchangeably, i.e. dr/dering are the same.
8637 The filters accept the following options:
8641 Set postprocessing subfilters string.
8644 All subfilters share common options to determine their scope:
8648 Honor the quality commands for this subfilter.
8651 Do chrominance filtering, too (default).
8654 Do luminance filtering only (no chrominance).
8657 Do chrominance filtering only (no luminance).
8660 These options can be appended after the subfilter name, separated by a '|'.
8662 Available subfilters are:
8665 @item hb/hdeblock[|difference[|flatness]]
8666 Horizontal deblocking filter
8669 Difference factor where higher values mean more deblocking (default: @code{32}).
8671 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8674 @item vb/vdeblock[|difference[|flatness]]
8675 Vertical deblocking filter
8678 Difference factor where higher values mean more deblocking (default: @code{32}).
8680 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8683 @item ha/hadeblock[|difference[|flatness]]
8684 Accurate horizontal deblocking filter
8687 Difference factor where higher values mean more deblocking (default: @code{32}).
8689 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8692 @item va/vadeblock[|difference[|flatness]]
8693 Accurate vertical deblocking filter
8696 Difference factor where higher values mean more deblocking (default: @code{32}).
8698 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8702 The horizontal and vertical deblocking filters share the difference and
8703 flatness values so you cannot set different horizontal and vertical
8708 Experimental horizontal deblocking filter
8711 Experimental vertical deblocking filter
8716 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
8719 larger -> stronger filtering
8721 larger -> stronger filtering
8723 larger -> stronger filtering
8726 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
8729 Stretch luminance to @code{0-255}.
8732 @item lb/linblenddeint
8733 Linear blend deinterlacing filter that deinterlaces the given block by
8734 filtering all lines with a @code{(1 2 1)} filter.
8736 @item li/linipoldeint
8737 Linear interpolating deinterlacing filter that deinterlaces the given block by
8738 linearly interpolating every second line.
8740 @item ci/cubicipoldeint
8741 Cubic interpolating deinterlacing filter deinterlaces the given block by
8742 cubically interpolating every second line.
8744 @item md/mediandeint
8745 Median deinterlacing filter that deinterlaces the given block by applying a
8746 median filter to every second line.
8748 @item fd/ffmpegdeint
8749 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
8750 second line with a @code{(-1 4 2 4 -1)} filter.
8753 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
8754 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
8756 @item fq/forceQuant[|quantizer]
8757 Overrides the quantizer table from the input with the constant quantizer you
8765 Default pp filter combination (@code{hb|a,vb|a,dr|a})
8768 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
8771 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
8774 @subsection Examples
8778 Apply horizontal and vertical deblocking, deringing and automatic
8779 brightness/contrast:
8785 Apply default filters without brightness/contrast correction:
8791 Apply default filters and temporal denoiser:
8793 pp=default/tmpnoise|1|2|3
8797 Apply deblocking on luminance only, and switch vertical deblocking on or off
8798 automatically depending on available CPU time:
8805 Apply Postprocessing filter 7. It is variant of the @ref{spp} filter,
8806 similar to spp = 6 with 7 point DCT, where only the center sample is
8809 The filter accepts the following options:
8813 Force a constant quantization parameter. It accepts an integer in range
8814 0 to 63. If not set, the filter will use the QP from the video stream
8818 Set thresholding mode. Available modes are:
8822 Set hard thresholding.
8824 Set soft thresholding (better de-ringing effect, but likely blurrier).
8826 Set medium thresholding (good results, default).
8832 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
8833 Ratio) between two input videos.
8835 This filter takes in input two input videos, the first input is
8836 considered the "main" source and is passed unchanged to the
8837 output. The second input is used as a "reference" video for computing
8840 Both video inputs must have the same resolution and pixel format for
8841 this filter to work correctly. Also it assumes that both inputs
8842 have the same number of frames, which are compared one by one.
8844 The obtained average PSNR is printed through the logging system.
8846 The filter stores the accumulated MSE (mean squared error) of each
8847 frame, and at the end of the processing it is averaged across all frames
8848 equally, and the following formula is applied to obtain the PSNR:
8851 PSNR = 10*log10(MAX^2/MSE)
8854 Where MAX is the average of the maximum values of each component of the
8857 The description of the accepted parameters follows.
8861 If specified the filter will use the named file to save the PSNR of
8862 each individual frame.
8865 The file printed if @var{stats_file} is selected, contains a sequence of
8866 key/value pairs of the form @var{key}:@var{value} for each compared
8869 A description of each shown parameter follows:
8873 sequential number of the input frame, starting from 1
8876 Mean Square Error pixel-by-pixel average difference of the compared
8877 frames, averaged over all the image components.
8879 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
8880 Mean Square Error pixel-by-pixel average difference of the compared
8881 frames for the component specified by the suffix.
8883 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
8884 Peak Signal to Noise ratio of the compared frames for the component
8885 specified by the suffix.
8890 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
8891 [main][ref] psnr="stats_file=stats.log" [out]
8894 On this example the input file being processed is compared with the
8895 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
8896 is stored in @file{stats.log}.
8901 Pulldown reversal (inverse telecine) filter, capable of handling mixed
8902 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
8905 The pullup filter is designed to take advantage of future context in making
8906 its decisions. This filter is stateless in the sense that it does not lock
8907 onto a pattern to follow, but it instead looks forward to the following
8908 fields in order to identify matches and rebuild progressive frames.
8910 To produce content with an even framerate, insert the fps filter after
8911 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
8912 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
8914 The filter accepts the following options:
8921 These options set the amount of "junk" to ignore at the left, right, top, and
8922 bottom of the image, respectively. Left and right are in units of 8 pixels,
8923 while top and bottom are in units of 2 lines.
8924 The default is 8 pixels on each side.
8927 Set the strict breaks. Setting this option to 1 will reduce the chances of
8928 filter generating an occasional mismatched frame, but it may also cause an
8929 excessive number of frames to be dropped during high motion sequences.
8930 Conversely, setting it to -1 will make filter match fields more easily.
8931 This may help processing of video where there is slight blurring between
8932 the fields, but may also cause there to be interlaced frames in the output.
8933 Default value is @code{0}.
8936 Set the metric plane to use. It accepts the following values:
8942 Use chroma blue plane.
8945 Use chroma red plane.
8948 This option may be set to use chroma plane instead of the default luma plane
8949 for doing filter's computations. This may improve accuracy on very clean
8950 source material, but more likely will decrease accuracy, especially if there
8951 is chroma noise (rainbow effect) or any grayscale video.
8952 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
8953 load and make pullup usable in realtime on slow machines.
8956 For best results (without duplicated frames in the output file) it is
8957 necessary to change the output frame rate. For example, to inverse
8958 telecine NTSC input:
8960 ffmpeg -i input -vf pullup -r 24000/1001 ...
8965 Change video quantization parameters (QP).
8967 The filter accepts the following option:
8971 Set expression for quantization parameter.
8974 The expression is evaluated through the eval API and can contain, among others,
8975 the following constants:
8979 1 if index is not 129, 0 otherwise.
8982 Sequentional index starting from -129 to 128.
8985 @subsection Examples
8997 Flush video frames from internal cache of frames into a random order.
8998 No frame is discarded.
8999 Inspired by @ref{frei0r} nervous filter.
9003 Set size in number of frames of internal cache, in range from @code{2} to
9004 @code{512}. Default is @code{30}.
9007 Set seed for random number generator, must be an integer included between
9008 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9009 less than @code{0}, the filter will try to use a good random seed on a
9013 @section removegrain
9015 The removegrain filter is a spatial denoiser for progressive video.
9019 Set mode for the first plane.
9022 Set mode for the second plane.
9025 Set mode for the third plane.
9028 Set mode for the fourth plane.
9031 Range of mode is from 0 to 24. Description of each mode follows:
9035 Leave input plane unchanged. Default.
9038 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
9041 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
9044 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
9047 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
9048 This is equivalent to a median filter.
9051 Line-sensitive clipping giving the minimal change.
9054 Line-sensitive clipping, intermediate.
9057 Line-sensitive clipping, intermediate.
9060 Line-sensitive clipping, intermediate.
9063 Line-sensitive clipping on a line where the neighbours pixels are the closest.
9066 Replaces the target pixel with the closest neighbour.
9069 [1 2 1] horizontal and vertical kernel blur.
9075 Bob mode, interpolates top field from the line where the neighbours
9076 pixels are the closest.
9079 Bob mode, interpolates bottom field from the line where the neighbours
9080 pixels are the closest.
9083 Bob mode, interpolates top field. Same as 13 but with a more complicated
9084 interpolation formula.
9087 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
9088 interpolation formula.
9091 Clips the pixel with the minimum and maximum of respectively the maximum and
9092 minimum of each pair of opposite neighbour pixels.
9095 Line-sensitive clipping using opposite neighbours whose greatest distance from
9096 the current pixel is minimal.
9099 Replaces the pixel with the average of its 8 neighbours.
9102 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
9105 Clips pixels using the averages of opposite neighbour.
9108 Same as mode 21 but simpler and faster.
9111 Small edge and halo removal, but reputed useless.
9119 Suppress a TV station logo, using an image file to determine which
9120 pixels comprise the logo. It works by filling in the pixels that
9121 comprise the logo with neighboring pixels.
9123 The filter accepts the following options:
9127 Set the filter bitmap file, which can be any image format supported by
9128 libavformat. The width and height of the image file must match those of the
9129 video stream being processed.
9132 Pixels in the provided bitmap image with a value of zero are not
9133 considered part of the logo, non-zero pixels are considered part of
9134 the logo. If you use white (255) for the logo and black (0) for the
9135 rest, you will be safe. For making the filter bitmap, it is
9136 recommended to take a screen capture of a black frame with the logo
9137 visible, and then using a threshold filter followed by the erode
9138 filter once or twice.
9140 If needed, little splotches can be fixed manually. Remember that if
9141 logo pixels are not covered, the filter quality will be much
9142 reduced. Marking too many pixels as part of the logo does not hurt as
9143 much, but it will increase the amount of blurring needed to cover over
9144 the image and will destroy more information than necessary, and extra
9145 pixels will slow things down on a large logo.
9147 @section repeatfields
9149 This filter uses the repeat_field flag from the Video ES headers and hard repeats
9150 fields based on its value.
9152 @section reverse, areverse
9156 Warning: This filter requires memory to buffer the entire clip, so trimming
9159 @subsection Examples
9163 Take the first 5 seconds of a clip, and reverse it.
9171 Rotate video by an arbitrary angle expressed in radians.
9173 The filter accepts the following options:
9175 A description of the optional parameters follows.
9178 Set an expression for the angle by which to rotate the input video
9179 clockwise, expressed as a number of radians. A negative value will
9180 result in a counter-clockwise rotation. By default it is set to "0".
9182 This expression is evaluated for each frame.
9185 Set the output width expression, default value is "iw".
9186 This expression is evaluated just once during configuration.
9189 Set the output height expression, default value is "ih".
9190 This expression is evaluated just once during configuration.
9193 Enable bilinear interpolation if set to 1, a value of 0 disables
9194 it. Default value is 1.
9197 Set the color used to fill the output area not covered by the rotated
9198 image. For the general syntax of this option, check the "Color" section in the
9199 ffmpeg-utils manual. If the special value "none" is selected then no
9200 background is printed (useful for example if the background is never shown).
9202 Default value is "black".
9205 The expressions for the angle and the output size can contain the
9206 following constants and functions:
9210 sequential number of the input frame, starting from 0. It is always NAN
9211 before the first frame is filtered.
9214 time in seconds of the input frame, it is set to 0 when the filter is
9215 configured. It is always NAN before the first frame is filtered.
9219 horizontal and vertical chroma subsample values. For example for the
9220 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9224 the input video width and height
9228 the output width and height, that is the size of the padded area as
9229 specified by the @var{width} and @var{height} expressions
9233 the minimal width/height required for completely containing the input
9234 video rotated by @var{a} radians.
9236 These are only available when computing the @option{out_w} and
9237 @option{out_h} expressions.
9240 @subsection Examples
9244 Rotate the input by PI/6 radians clockwise:
9250 Rotate the input by PI/6 radians counter-clockwise:
9256 Rotate the input by 45 degrees clockwise:
9262 Apply a constant rotation with period T, starting from an angle of PI/3:
9264 rotate=PI/3+2*PI*t/T
9268 Make the input video rotation oscillating with a period of T
9269 seconds and an amplitude of A radians:
9271 rotate=A*sin(2*PI/T*t)
9275 Rotate the video, output size is chosen so that the whole rotating
9276 input video is always completely contained in the output:
9278 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
9282 Rotate the video, reduce the output size so that no background is ever
9285 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
9289 @subsection Commands
9291 The filter supports the following commands:
9295 Set the angle expression.
9296 The command accepts the same syntax of the corresponding option.
9298 If the specified expression is not valid, it is kept at its current
9304 Apply Shape Adaptive Blur.
9306 The filter accepts the following options:
9309 @item luma_radius, lr
9310 Set luma blur filter strength, must be a value in range 0.1-4.0, default
9311 value is 1.0. A greater value will result in a more blurred image, and
9312 in slower processing.
9314 @item luma_pre_filter_radius, lpfr
9315 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
9318 @item luma_strength, ls
9319 Set luma maximum difference between pixels to still be considered, must
9320 be a value in the 0.1-100.0 range, default value is 1.0.
9322 @item chroma_radius, cr
9323 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
9324 greater value will result in a more blurred image, and in slower
9327 @item chroma_pre_filter_radius, cpfr
9328 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
9330 @item chroma_strength, cs
9331 Set chroma maximum difference between pixels to still be considered,
9332 must be a value in the 0.1-100.0 range.
9335 Each chroma option value, if not explicitly specified, is set to the
9336 corresponding luma option value.
9341 Scale (resize) the input video, using the libswscale library.
9343 The scale filter forces the output display aspect ratio to be the same
9344 of the input, by changing the output sample aspect ratio.
9346 If the input image format is different from the format requested by
9347 the next filter, the scale filter will convert the input to the
9351 The filter accepts the following options, or any of the options
9352 supported by the libswscale scaler.
9354 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
9355 the complete list of scaler options.
9360 Set the output video dimension expression. Default value is the input
9363 If the value is 0, the input width is used for the output.
9365 If one of the values is -1, the scale filter will use a value that
9366 maintains the aspect ratio of the input image, calculated from the
9367 other specified dimension. If both of them are -1, the input size is
9370 If one of the values is -n with n > 1, the scale filter will also use a value
9371 that maintains the aspect ratio of the input image, calculated from the other
9372 specified dimension. After that it will, however, make sure that the calculated
9373 dimension is divisible by n and adjust the value if necessary.
9375 See below for the list of accepted constants for use in the dimension
9379 Set the interlacing mode. It accepts the following values:
9383 Force interlaced aware scaling.
9386 Do not apply interlaced scaling.
9389 Select interlaced aware scaling depending on whether the source frames
9390 are flagged as interlaced or not.
9393 Default value is @samp{0}.
9396 Set libswscale scaling flags. See
9397 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
9398 complete list of values. If not explicitly specified the filter applies
9402 Set the video size. For the syntax of this option, check the
9403 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9405 @item in_color_matrix
9406 @item out_color_matrix
9407 Set in/output YCbCr color space type.
9409 This allows the autodetected value to be overridden as well as allows forcing
9410 a specific value used for the output and encoder.
9412 If not specified, the color space type depends on the pixel format.
9418 Choose automatically.
9421 Format conforming to International Telecommunication Union (ITU)
9422 Recommendation BT.709.
9425 Set color space conforming to the United States Federal Communications
9426 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
9429 Set color space conforming to:
9433 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
9436 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
9439 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
9444 Set color space conforming to SMPTE ST 240:1999.
9449 Set in/output YCbCr sample range.
9451 This allows the autodetected value to be overridden as well as allows forcing
9452 a specific value used for the output and encoder. If not specified, the
9453 range depends on the pixel format. Possible values:
9457 Choose automatically.
9460 Set full range (0-255 in case of 8-bit luma).
9463 Set "MPEG" range (16-235 in case of 8-bit luma).
9466 @item force_original_aspect_ratio
9467 Enable decreasing or increasing output video width or height if necessary to
9468 keep the original aspect ratio. Possible values:
9472 Scale the video as specified and disable this feature.
9475 The output video dimensions will automatically be decreased if needed.
9478 The output video dimensions will automatically be increased if needed.
9482 One useful instance of this option is that when you know a specific device's
9483 maximum allowed resolution, you can use this to limit the output video to
9484 that, while retaining the aspect ratio. For example, device A allows
9485 1280x720 playback, and your video is 1920x800. Using this option (set it to
9486 decrease) and specifying 1280x720 to the command line makes the output
9489 Please note that this is a different thing than specifying -1 for @option{w}
9490 or @option{h}, you still need to specify the output resolution for this option
9495 The values of the @option{w} and @option{h} options are expressions
9496 containing the following constants:
9501 The input width and height
9505 These are the same as @var{in_w} and @var{in_h}.
9509 The output (scaled) width and height
9513 These are the same as @var{out_w} and @var{out_h}
9516 The same as @var{iw} / @var{ih}
9519 input sample aspect ratio
9522 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
9526 horizontal and vertical input chroma subsample values. For example for the
9527 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9531 horizontal and vertical output chroma subsample values. For example for the
9532 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9535 @subsection Examples
9539 Scale the input video to a size of 200x100
9544 This is equivalent to:
9555 Specify a size abbreviation for the output size:
9560 which can also be written as:
9566 Scale the input to 2x:
9572 The above is the same as:
9578 Scale the input to 2x with forced interlaced scaling:
9580 scale=2*iw:2*ih:interl=1
9584 Scale the input to half size:
9590 Increase the width, and set the height to the same size:
9603 Increase the height, and set the width to 3/2 of the height:
9605 scale=w=3/2*oh:h=3/5*ih
9609 Increase the size, making the size a multiple of the chroma
9612 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
9616 Increase the width to a maximum of 500 pixels,
9617 keeping the same aspect ratio as the input:
9619 scale=w='min(500\, iw*3/2):h=-1'
9623 @subsection Commands
9625 This filter supports the following commands:
9629 Set the output video dimension expression.
9630 The command accepts the same syntax of the corresponding option.
9632 If the specified expression is not valid, it is kept at its current
9638 Scale (resize) the input video, based on a reference video.
9640 See the scale filter for available options, scale2ref supports the same but
9641 uses the reference video instead of the main input as basis.
9643 @subsection Examples
9647 Scale a subtitle stream to match the main video in size before overlaying
9649 'scale2ref[b][a];[a][b]overlay'
9653 @section separatefields
9655 The @code{separatefields} takes a frame-based video input and splits
9656 each frame into its components fields, producing a new half height clip
9657 with twice the frame rate and twice the frame count.
9659 This filter use field-dominance information in frame to decide which
9660 of each pair of fields to place first in the output.
9661 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
9663 @section setdar, setsar
9665 The @code{setdar} filter sets the Display Aspect Ratio for the filter
9668 This is done by changing the specified Sample (aka Pixel) Aspect
9669 Ratio, according to the following equation:
9671 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
9674 Keep in mind that the @code{setdar} filter does not modify the pixel
9675 dimensions of the video frame. Also, the display aspect ratio set by
9676 this filter may be changed by later filters in the filterchain,
9677 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
9680 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
9681 the filter output video.
9683 Note that as a consequence of the application of this filter, the
9684 output display aspect ratio will change according to the equation
9687 Keep in mind that the sample aspect ratio set by the @code{setsar}
9688 filter may be changed by later filters in the filterchain, e.g. if
9689 another "setsar" or a "setdar" filter is applied.
9691 It accepts the following parameters:
9694 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
9695 Set the aspect ratio used by the filter.
9697 The parameter can be a floating point number string, an expression, or
9698 a string of the form @var{num}:@var{den}, where @var{num} and
9699 @var{den} are the numerator and denominator of the aspect ratio. If
9700 the parameter is not specified, it is assumed the value "0".
9701 In case the form "@var{num}:@var{den}" is used, the @code{:} character
9705 Set the maximum integer value to use for expressing numerator and
9706 denominator when reducing the expressed aspect ratio to a rational.
9707 Default value is @code{100}.
9711 The parameter @var{sar} is an expression containing
9712 the following constants:
9716 These are approximated values for the mathematical constants e
9717 (Euler's number), pi (Greek pi), and phi (the golden ratio).
9720 The input width and height.
9723 These are the same as @var{w} / @var{h}.
9726 The input sample aspect ratio.
9729 The input display aspect ratio. It is the same as
9730 (@var{w} / @var{h}) * @var{sar}.
9733 Horizontal and vertical chroma subsample values. For example, for the
9734 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9737 @subsection Examples
9742 To change the display aspect ratio to 16:9, specify one of the following:
9750 To change the sample aspect ratio to 10:11, specify:
9756 To set a display aspect ratio of 16:9, and specify a maximum integer value of
9757 1000 in the aspect ratio reduction, use the command:
9759 setdar=ratio=16/9:max=1000
9767 Force field for the output video frame.
9769 The @code{setfield} filter marks the interlace type field for the
9770 output frames. It does not change the input frame, but only sets the
9771 corresponding property, which affects how the frame is treated by
9772 following filters (e.g. @code{fieldorder} or @code{yadif}).
9774 The filter accepts the following options:
9779 Available values are:
9783 Keep the same field property.
9786 Mark the frame as bottom-field-first.
9789 Mark the frame as top-field-first.
9792 Mark the frame as progressive.
9798 Show a line containing various information for each input video frame.
9799 The input video is not modified.
9801 The shown line contains a sequence of key/value pairs of the form
9802 @var{key}:@var{value}.
9804 The following values are shown in the output:
9808 The (sequential) number of the input frame, starting from 0.
9811 The Presentation TimeStamp of the input frame, expressed as a number of
9812 time base units. The time base unit depends on the filter input pad.
9815 The Presentation TimeStamp of the input frame, expressed as a number of
9819 The position of the frame in the input stream, or -1 if this information is
9820 unavailable and/or meaningless (for example in case of synthetic video).
9823 The pixel format name.
9826 The sample aspect ratio of the input frame, expressed in the form
9827 @var{num}/@var{den}.
9830 The size of the input frame. For the syntax of this option, check the
9831 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9834 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
9835 for bottom field first).
9838 This is 1 if the frame is a key frame, 0 otherwise.
9841 The picture type of the input frame ("I" for an I-frame, "P" for a
9842 P-frame, "B" for a B-frame, or "?" for an unknown type).
9843 Also refer to the documentation of the @code{AVPictureType} enum and of
9844 the @code{av_get_picture_type_char} function defined in
9845 @file{libavutil/avutil.h}.
9848 The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
9850 @item plane_checksum
9851 The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
9852 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]".
9855 @section showpalette
9857 Displays the 256 colors palette of each frame. This filter is only relevant for
9858 @var{pal8} pixel format frames.
9860 It accepts the following option:
9864 Set the size of the box used to represent one palette color entry. Default is
9865 @code{30} (for a @code{30x30} pixel box).
9868 @section shuffleplanes
9870 Reorder and/or duplicate video planes.
9872 It accepts the following parameters:
9877 The index of the input plane to be used as the first output plane.
9880 The index of the input plane to be used as the second output plane.
9883 The index of the input plane to be used as the third output plane.
9886 The index of the input plane to be used as the fourth output plane.
9890 The first plane has the index 0. The default is to keep the input unchanged.
9892 Swap the second and third planes of the input:
9894 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
9897 @anchor{signalstats}
9898 @section signalstats
9899 Evaluate various visual metrics that assist in determining issues associated
9900 with the digitization of analog video media.
9902 By default the filter will log these metadata values:
9906 Display the minimal Y value contained within the input frame. Expressed in
9910 Display the Y value at the 10% percentile within the input frame. Expressed in
9914 Display the average Y value within the input frame. Expressed in range of
9918 Display the Y value at the 90% percentile within the input frame. Expressed in
9922 Display the maximum Y value contained within the input frame. Expressed in
9926 Display the minimal U value contained within the input frame. Expressed in
9930 Display the U value at the 10% percentile within the input frame. Expressed in
9934 Display the average U value within the input frame. Expressed in range of
9938 Display the U value at the 90% percentile within the input frame. Expressed in
9942 Display the maximum U value contained within the input frame. Expressed in
9946 Display the minimal V value contained within the input frame. Expressed in
9950 Display the V value at the 10% percentile within the input frame. Expressed in
9954 Display the average V value within the input frame. Expressed in range of
9958 Display the V value at the 90% percentile within the input frame. Expressed in
9962 Display the maximum V value contained within the input frame. Expressed in
9966 Display the minimal saturation value contained within the input frame.
9967 Expressed in range of [0-~181.02].
9970 Display the saturation value at the 10% percentile within the input frame.
9971 Expressed in range of [0-~181.02].
9974 Display the average saturation value within the input frame. Expressed in range
9978 Display the saturation value at the 90% percentile within the input frame.
9979 Expressed in range of [0-~181.02].
9982 Display the maximum saturation value contained within the input frame.
9983 Expressed in range of [0-~181.02].
9986 Display the median value for hue within the input frame. Expressed in range of
9990 Display the average value for hue within the input frame. Expressed in range of
9994 Display the average of sample value difference between all values of the Y
9995 plane in the current frame and corresponding values of the previous input frame.
9996 Expressed in range of [0-255].
9999 Display the average of sample value difference between all values of the U
10000 plane in the current frame and corresponding values of the previous input frame.
10001 Expressed in range of [0-255].
10004 Display the average of sample value difference between all values of the V
10005 plane in the current frame and corresponding values of the previous input frame.
10006 Expressed in range of [0-255].
10009 The filter accepts the following options:
10015 @option{stat} specify an additional form of image analysis.
10016 @option{out} output video with the specified type of pixel highlighted.
10018 Both options accept the following values:
10022 Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel
10023 unlike the neighboring pixels of the same field. Examples of temporal outliers
10024 include the results of video dropouts, head clogs, or tape tracking issues.
10027 Identify @var{vertical line repetition}. Vertical line repetition includes
10028 similar rows of pixels within a frame. In born-digital video vertical line
10029 repetition is common, but this pattern is uncommon in video digitized from an
10030 analog source. When it occurs in video that results from the digitization of an
10031 analog source it can indicate concealment from a dropout compensator.
10034 Identify pixels that fall outside of legal broadcast range.
10038 Set the highlight color for the @option{out} option. The default color is
10042 @subsection Examples
10046 Output data of various video metrics:
10048 ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
10052 Output specific data about the minimum and maximum values of the Y plane per frame:
10054 ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
10058 Playback video while highlighting pixels that are outside of broadcast range in red.
10060 ffplay example.mov -vf signalstats="out=brng:color=red"
10064 Playback video with signalstats metadata drawn over the frame.
10066 ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
10069 The contents of signalstat_drawtext.txt used in the command are:
10072 Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@})
10073 U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@})
10074 V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@})
10075 saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@}
10083 Blur the input video without impacting the outlines.
10085 It accepts the following options:
10088 @item luma_radius, lr
10089 Set the luma radius. The option value must be a float number in
10090 the range [0.1,5.0] that specifies the variance of the gaussian filter
10091 used to blur the image (slower if larger). Default value is 1.0.
10093 @item luma_strength, ls
10094 Set the luma strength. The option value must be a float number
10095 in the range [-1.0,1.0] that configures the blurring. A value included
10096 in [0.0,1.0] will blur the image whereas a value included in
10097 [-1.0,0.0] will sharpen the image. Default value is 1.0.
10099 @item luma_threshold, lt
10100 Set the luma threshold used as a coefficient to determine
10101 whether a pixel should be blurred or not. The option value must be an
10102 integer in the range [-30,30]. A value of 0 will filter all the image,
10103 a value included in [0,30] will filter flat areas and a value included
10104 in [-30,0] will filter edges. Default value is 0.
10106 @item chroma_radius, cr
10107 Set the chroma radius. The option value must be a float number in
10108 the range [0.1,5.0] that specifies the variance of the gaussian filter
10109 used to blur the image (slower if larger). Default value is 1.0.
10111 @item chroma_strength, cs
10112 Set the chroma strength. The option value must be a float number
10113 in the range [-1.0,1.0] that configures the blurring. A value included
10114 in [0.0,1.0] will blur the image whereas a value included in
10115 [-1.0,0.0] will sharpen the image. Default value is 1.0.
10117 @item chroma_threshold, ct
10118 Set the chroma threshold used as a coefficient to determine
10119 whether a pixel should be blurred or not. The option value must be an
10120 integer in the range [-30,30]. A value of 0 will filter all the image,
10121 a value included in [0,30] will filter flat areas and a value included
10122 in [-30,0] will filter edges. Default value is 0.
10125 If a chroma option is not explicitly set, the corresponding luma value
10130 Obtain the SSIM (Structural SImilarity Metric) between two input videos.
10132 This filter takes in input two input videos, the first input is
10133 considered the "main" source and is passed unchanged to the
10134 output. The second input is used as a "reference" video for computing
10137 Both video inputs must have the same resolution and pixel format for
10138 this filter to work correctly. Also it assumes that both inputs
10139 have the same number of frames, which are compared one by one.
10141 The filter stores the calculated SSIM of each frame.
10143 The description of the accepted parameters follows.
10146 @item stats_file, f
10147 If specified the filter will use the named file to save the SSIM of
10148 each individual frame.
10151 The file printed if @var{stats_file} is selected, contains a sequence of
10152 key/value pairs of the form @var{key}:@var{value} for each compared
10155 A description of each shown parameter follows:
10159 sequential number of the input frame, starting from 1
10161 @item Y, U, V, R, G, B
10162 SSIM of the compared frames for the component specified by the suffix.
10165 SSIM of the compared frames for the whole frame.
10168 Same as above but in dB representation.
10173 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
10174 [main][ref] ssim="stats_file=stats.log" [out]
10177 On this example the input file being processed is compared with the
10178 reference file @file{ref_movie.mpg}. The SSIM of each individual frame
10179 is stored in @file{stats.log}.
10181 Another example with both psnr and ssim at same time:
10183 ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
10188 Convert between different stereoscopic image formats.
10190 The filters accept the following options:
10194 Set stereoscopic image format of input.
10196 Available values for input image formats are:
10199 side by side parallel (left eye left, right eye right)
10202 side by side crosseye (right eye left, left eye right)
10205 side by side parallel with half width resolution
10206 (left eye left, right eye right)
10209 side by side crosseye with half width resolution
10210 (right eye left, left eye right)
10213 above-below (left eye above, right eye below)
10216 above-below (right eye above, left eye below)
10219 above-below with half height resolution
10220 (left eye above, right eye below)
10223 above-below with half height resolution
10224 (right eye above, left eye below)
10227 alternating frames (left eye first, right eye second)
10230 alternating frames (right eye first, left eye second)
10233 interleaved rows (left eye has top row, right eye starts on next row)
10236 interleaved rows (right eye has top row, left eye starts on next row)
10238 Default value is @samp{sbsl}.
10242 Set stereoscopic image format of output.
10244 Available values for output image formats are all the input formats as well as:
10247 anaglyph red/blue gray
10248 (red filter on left eye, blue filter on right eye)
10251 anaglyph red/green gray
10252 (red filter on left eye, green filter on right eye)
10255 anaglyph red/cyan gray
10256 (red filter on left eye, cyan filter on right eye)
10259 anaglyph red/cyan half colored
10260 (red filter on left eye, cyan filter on right eye)
10263 anaglyph red/cyan color
10264 (red filter on left eye, cyan filter on right eye)
10267 anaglyph red/cyan color optimized with the least squares projection of dubois
10268 (red filter on left eye, cyan filter on right eye)
10271 anaglyph green/magenta gray
10272 (green filter on left eye, magenta filter on right eye)
10275 anaglyph green/magenta half colored
10276 (green filter on left eye, magenta filter on right eye)
10279 anaglyph green/magenta colored
10280 (green filter on left eye, magenta filter on right eye)
10283 anaglyph green/magenta color optimized with the least squares projection of dubois
10284 (green filter on left eye, magenta filter on right eye)
10287 anaglyph yellow/blue gray
10288 (yellow filter on left eye, blue filter on right eye)
10291 anaglyph yellow/blue half colored
10292 (yellow filter on left eye, blue filter on right eye)
10295 anaglyph yellow/blue colored
10296 (yellow filter on left eye, blue filter on right eye)
10299 anaglyph yellow/blue color optimized with the least squares projection of dubois
10300 (yellow filter on left eye, blue filter on right eye)
10303 mono output (left eye only)
10306 mono output (right eye only)
10309 checkerboard, left eye first
10312 checkerboard, right eye first
10315 interleaved columns, left eye first
10318 interleaved columns, right eye first
10321 Default value is @samp{arcd}.
10324 @subsection Examples
10328 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
10334 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
10343 Apply a simple postprocessing filter that compresses and decompresses the image
10344 at several (or - in the case of @option{quality} level @code{6} - all) shifts
10345 and average the results.
10347 The filter accepts the following options:
10351 Set quality. This option defines the number of levels for averaging. It accepts
10352 an integer in the range 0-6. If set to @code{0}, the filter will have no
10353 effect. A value of @code{6} means the higher quality. For each increment of
10354 that value the speed drops by a factor of approximately 2. Default value is
10358 Force a constant quantization parameter. If not set, the filter will use the QP
10359 from the video stream (if available).
10362 Set thresholding mode. Available modes are:
10366 Set hard thresholding (default).
10368 Set soft thresholding (better de-ringing effect, but likely blurrier).
10371 @item use_bframe_qp
10372 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
10373 option may cause flicker since the B-Frames have often larger QP. Default is
10374 @code{0} (not enabled).
10380 Draw subtitles on top of input video using the libass library.
10382 To enable compilation of this filter you need to configure FFmpeg with
10383 @code{--enable-libass}. This filter also requires a build with libavcodec and
10384 libavformat to convert the passed subtitles file to ASS (Advanced Substation
10385 Alpha) subtitles format.
10387 The filter accepts the following options:
10391 Set the filename of the subtitle file to read. It must be specified.
10393 @item original_size
10394 Specify the size of the original video, the video for which the ASS file
10395 was composed. For the syntax of this option, check the
10396 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10397 Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
10398 correctly scale the fonts if the aspect ratio has been changed.
10401 Set a directory path containing fonts that can be used by the filter.
10402 These fonts will be used in addition to whatever the font provider uses.
10405 Set subtitles input character encoding. @code{subtitles} filter only. Only
10406 useful if not UTF-8.
10408 @item stream_index, si
10409 Set subtitles stream index. @code{subtitles} filter only.
10412 Override default style or script info parameters of the subtitles. It accepts a
10413 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
10416 If the first key is not specified, it is assumed that the first value
10417 specifies the @option{filename}.
10419 For example, to render the file @file{sub.srt} on top of the input
10420 video, use the command:
10425 which is equivalent to:
10427 subtitles=filename=sub.srt
10430 To render the default subtitles stream from file @file{video.mkv}, use:
10432 subtitles=video.mkv
10435 To render the second subtitles stream from that file, use:
10437 subtitles=video.mkv:si=1
10440 To make the subtitles stream from @file{sub.srt} appear in transparent green
10441 @code{DejaVu Serif}, use:
10443 subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
10446 @section super2xsai
10448 Scale the input by 2x and smooth using the Super2xSaI (Scale and
10449 Interpolate) pixel art scaling algorithm.
10451 Useful for enlarging pixel art images without reducing sharpness.
10458 Apply telecine process to the video.
10460 This filter accepts the following options:
10469 The default value is @code{top}.
10473 A string of numbers representing the pulldown pattern you wish to apply.
10474 The default value is @code{23}.
10478 Some typical patterns:
10483 24p: 2332 (preferred)
10490 24p: 222222222223 ("Euro pulldown")
10496 Select the most representative frame in a given sequence of consecutive frames.
10498 The filter accepts the following options:
10502 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
10503 will pick one of them, and then handle the next batch of @var{n} frames until
10504 the end. Default is @code{100}.
10507 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
10508 value will result in a higher memory usage, so a high value is not recommended.
10510 @subsection Examples
10514 Extract one picture each 50 frames:
10520 Complete example of a thumbnail creation with @command{ffmpeg}:
10522 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
10528 Tile several successive frames together.
10530 The filter accepts the following options:
10535 Set the grid size (i.e. the number of lines and columns). For the syntax of
10536 this option, check the
10537 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10540 Set the maximum number of frames to render in the given area. It must be less
10541 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
10542 the area will be used.
10545 Set the outer border margin in pixels.
10548 Set the inner border thickness (i.e. the number of pixels between frames). For
10549 more advanced padding options (such as having different values for the edges),
10550 refer to the pad video filter.
10553 Specify the color of the unused area. For the syntax of this option, check the
10554 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
10558 @subsection Examples
10562 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
10564 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
10566 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
10567 duplicating each output frame to accommodate the originally detected frame
10571 Display @code{5} pictures in an area of @code{3x2} frames,
10572 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
10573 mixed flat and named options:
10575 tile=3x2:nb_frames=5:padding=7:margin=2
10579 @section tinterlace
10581 Perform various types of temporal field interlacing.
10583 Frames are counted starting from 1, so the first input frame is
10586 The filter accepts the following options:
10591 Specify the mode of the interlacing. This option can also be specified
10592 as a value alone. See below for a list of values for this option.
10594 Available values are:
10598 Move odd frames into the upper field, even into the lower field,
10599 generating a double height frame at half frame rate.
10603 Frame 1 Frame 2 Frame 3 Frame 4
10605 11111 22222 33333 44444
10606 11111 22222 33333 44444
10607 11111 22222 33333 44444
10608 11111 22222 33333 44444
10622 Only output even frames, odd frames are dropped, generating a frame with
10623 unchanged height at half frame rate.
10628 Frame 1 Frame 2 Frame 3 Frame 4
10630 11111 22222 33333 44444
10631 11111 22222 33333 44444
10632 11111 22222 33333 44444
10633 11111 22222 33333 44444
10643 Only output odd frames, even frames are dropped, generating a frame with
10644 unchanged height at half frame rate.
10649 Frame 1 Frame 2 Frame 3 Frame 4
10651 11111 22222 33333 44444
10652 11111 22222 33333 44444
10653 11111 22222 33333 44444
10654 11111 22222 33333 44444
10664 Expand each frame to full height, but pad alternate lines with black,
10665 generating a frame with double height at the same input frame rate.
10670 Frame 1 Frame 2 Frame 3 Frame 4
10672 11111 22222 33333 44444
10673 11111 22222 33333 44444
10674 11111 22222 33333 44444
10675 11111 22222 33333 44444
10678 11111 ..... 33333 .....
10679 ..... 22222 ..... 44444
10680 11111 ..... 33333 .....
10681 ..... 22222 ..... 44444
10682 11111 ..... 33333 .....
10683 ..... 22222 ..... 44444
10684 11111 ..... 33333 .....
10685 ..... 22222 ..... 44444
10689 @item interleave_top, 4
10690 Interleave the upper field from odd frames with the lower field from
10691 even frames, generating a frame with unchanged height at half frame rate.
10696 Frame 1 Frame 2 Frame 3 Frame 4
10698 11111<- 22222 33333<- 44444
10699 11111 22222<- 33333 44444<-
10700 11111<- 22222 33333<- 44444
10701 11111 22222<- 33333 44444<-
10711 @item interleave_bottom, 5
10712 Interleave the lower field from odd frames with the upper field from
10713 even frames, generating a frame with unchanged height at half frame rate.
10718 Frame 1 Frame 2 Frame 3 Frame 4
10720 11111 22222<- 33333 44444<-
10721 11111<- 22222 33333<- 44444
10722 11111 22222<- 33333 44444<-
10723 11111<- 22222 33333<- 44444
10733 @item interlacex2, 6
10734 Double frame rate with unchanged height. Frames are inserted each
10735 containing the second temporal field from the previous input frame and
10736 the first temporal field from the next input frame. This mode relies on
10737 the top_field_first flag. Useful for interlaced video displays with no
10738 field synchronisation.
10743 Frame 1 Frame 2 Frame 3 Frame 4
10745 11111 22222 33333 44444
10746 11111 22222 33333 44444
10747 11111 22222 33333 44444
10748 11111 22222 33333 44444
10751 11111 22222 22222 33333 33333 44444 44444
10752 11111 11111 22222 22222 33333 33333 44444
10753 11111 22222 22222 33333 33333 44444 44444
10754 11111 11111 22222 22222 33333 33333 44444
10760 Numeric values are deprecated but are accepted for backward
10761 compatibility reasons.
10763 Default mode is @code{merge}.
10766 Specify flags influencing the filter process.
10768 Available value for @var{flags} is:
10771 @item low_pass_filter, vlfp
10772 Enable vertical low-pass filtering in the filter.
10773 Vertical low-pass filtering is required when creating an interlaced
10774 destination from a progressive source which contains high-frequency
10775 vertical detail. Filtering will reduce interlace 'twitter' and Moire
10778 Vertical low-pass filtering can only be enabled for @option{mode}
10779 @var{interleave_top} and @var{interleave_bottom}.
10786 Transpose rows with columns in the input video and optionally flip it.
10788 It accepts the following parameters:
10793 Specify the transposition direction.
10795 Can assume the following values:
10797 @item 0, 4, cclock_flip
10798 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
10806 Rotate by 90 degrees clockwise, that is:
10814 Rotate by 90 degrees counterclockwise, that is:
10821 @item 3, 7, clock_flip
10822 Rotate by 90 degrees clockwise and vertically flip, that is:
10830 For values between 4-7, the transposition is only done if the input
10831 video geometry is portrait and not landscape. These values are
10832 deprecated, the @code{passthrough} option should be used instead.
10834 Numerical values are deprecated, and should be dropped in favor of
10835 symbolic constants.
10838 Do not apply the transposition if the input geometry matches the one
10839 specified by the specified value. It accepts the following values:
10842 Always apply transposition.
10844 Preserve portrait geometry (when @var{height} >= @var{width}).
10846 Preserve landscape geometry (when @var{width} >= @var{height}).
10849 Default value is @code{none}.
10852 For example to rotate by 90 degrees clockwise and preserve portrait
10855 transpose=dir=1:passthrough=portrait
10858 The command above can also be specified as:
10860 transpose=1:portrait
10864 Trim the input so that the output contains one continuous subpart of the input.
10866 It accepts the following parameters:
10869 Specify the time of the start of the kept section, i.e. the frame with the
10870 timestamp @var{start} will be the first frame in the output.
10873 Specify the time of the first frame that will be dropped, i.e. the frame
10874 immediately preceding the one with the timestamp @var{end} will be the last
10875 frame in the output.
10878 This is the same as @var{start}, except this option sets the start timestamp
10879 in timebase units instead of seconds.
10882 This is the same as @var{end}, except this option sets the end timestamp
10883 in timebase units instead of seconds.
10886 The maximum duration of the output in seconds.
10889 The number of the first frame that should be passed to the output.
10892 The number of the first frame that should be dropped.
10895 @option{start}, @option{end}, and @option{duration} are expressed as time
10896 duration specifications; see
10897 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
10898 for the accepted syntax.
10900 Note that the first two sets of the start/end options and the @option{duration}
10901 option look at the frame timestamp, while the _frame variants simply count the
10902 frames that pass through the filter. Also note that this filter does not modify
10903 the timestamps. If you wish for the output timestamps to start at zero, insert a
10904 setpts filter after the trim filter.
10906 If multiple start or end options are set, this filter tries to be greedy and
10907 keep all the frames that match at least one of the specified constraints. To keep
10908 only the part that matches all the constraints at once, chain multiple trim
10911 The defaults are such that all the input is kept. So it is possible to set e.g.
10912 just the end values to keep everything before the specified time.
10917 Drop everything except the second minute of input:
10919 ffmpeg -i INPUT -vf trim=60:120
10923 Keep only the first second:
10925 ffmpeg -i INPUT -vf trim=duration=1
10934 Sharpen or blur the input video.
10936 It accepts the following parameters:
10939 @item luma_msize_x, lx
10940 Set the luma matrix horizontal size. It must be an odd integer between
10941 3 and 63. The default value is 5.
10943 @item luma_msize_y, ly
10944 Set the luma matrix vertical size. It must be an odd integer between 3
10945 and 63. The default value is 5.
10947 @item luma_amount, la
10948 Set the luma effect strength. It must be a floating point number, reasonable
10949 values lay between -1.5 and 1.5.
10951 Negative values will blur the input video, while positive values will
10952 sharpen it, a value of zero will disable the effect.
10954 Default value is 1.0.
10956 @item chroma_msize_x, cx
10957 Set the chroma matrix horizontal size. It must be an odd integer
10958 between 3 and 63. The default value is 5.
10960 @item chroma_msize_y, cy
10961 Set the chroma matrix vertical size. It must be an odd integer
10962 between 3 and 63. The default value is 5.
10964 @item chroma_amount, ca
10965 Set the chroma effect strength. It must be a floating point number, reasonable
10966 values lay between -1.5 and 1.5.
10968 Negative values will blur the input video, while positive values will
10969 sharpen it, a value of zero will disable the effect.
10971 Default value is 0.0.
10974 If set to 1, specify using OpenCL capabilities, only available if
10975 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
10979 All parameters are optional and default to the equivalent of the
10980 string '5:5:1.0:5:5:0.0'.
10982 @subsection Examples
10986 Apply strong luma sharpen effect:
10988 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
10992 Apply a strong blur of both luma and chroma parameters:
10994 unsharp=7:7:-2:7:7:-2
11000 Apply ultra slow/simple postprocessing filter that compresses and decompresses
11001 the image at several (or - in the case of @option{quality} level @code{8} - all)
11002 shifts and average the results.
11004 The way this differs from the behavior of spp is that uspp actually encodes &
11005 decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
11006 DCT similar to MJPEG.
11008 The filter accepts the following options:
11012 Set quality. This option defines the number of levels for averaging. It accepts
11013 an integer in the range 0-8. If set to @code{0}, the filter will have no
11014 effect. A value of @code{8} means the higher quality. For each increment of
11015 that value the speed drops by a factor of approximately 2. Default value is
11019 Force a constant quantization parameter. If not set, the filter will use the QP
11020 from the video stream (if available).
11023 @section vectorscope
11025 Display 2 color component values in the two dimensional graph (which is called
11028 This filter accepts the following options:
11032 Set vectorscope mode.
11034 It accepts the following values:
11037 Gray values are displayed on graph, higher brightness means more pixels have
11038 same component color value on location in graph. This is the default mode.
11041 Gray values are displayed on graph. Surrounding pixels values which are not
11042 present in video frame are drawn in gradient of 2 color components which are
11043 set by option @code{x} and @code{y}.
11046 Actual color components values present in video frame are displayed on graph.
11049 Similar as color2 but higher frequency of same values @code{x} and @code{y}
11050 on graph increases value of another color component, which is luminance by
11051 default values of @code{x} and @code{y}.
11054 Actual colors present in video frame are displayed on graph. If two different
11055 colors map to same position on graph then color with higher value of component
11056 not present in graph is picked.
11060 Set which color component will be represented on X-axis. Default is @code{1}.
11063 Set which color component will be represented on Y-axis. Default is @code{2}.
11066 Set intensity, used by modes: gray, color and color3 for increasing brightness
11067 of color component which represents frequency of (X, Y) location in graph.
11072 No envelope, this is default.
11075 Instant envelope, even darkest single pixel will be clearly highlighted.
11078 Hold maximum and minimum values presented in graph over time. This way you
11079 can still spot out of range values without constantly looking at vectorscope.
11082 Peak and instant envelope combined together.
11086 @anchor{vidstabdetect}
11087 @section vidstabdetect
11089 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
11090 @ref{vidstabtransform} for pass 2.
11092 This filter generates a file with relative translation and rotation
11093 transform information about subsequent frames, which is then used by
11094 the @ref{vidstabtransform} filter.
11096 To enable compilation of this filter you need to configure FFmpeg with
11097 @code{--enable-libvidstab}.
11099 This filter accepts the following options:
11103 Set the path to the file used to write the transforms information.
11104 Default value is @file{transforms.trf}.
11107 Set how shaky the video is and how quick the camera is. It accepts an
11108 integer in the range 1-10, a value of 1 means little shakiness, a
11109 value of 10 means strong shakiness. Default value is 5.
11112 Set the accuracy of the detection process. It must be a value in the
11113 range 1-15. A value of 1 means low accuracy, a value of 15 means high
11114 accuracy. Default value is 15.
11117 Set stepsize of the search process. The region around minimum is
11118 scanned with 1 pixel resolution. Default value is 6.
11121 Set minimum contrast. Below this value a local measurement field is
11122 discarded. Must be a floating point value in the range 0-1. Default
11126 Set reference frame number for tripod mode.
11128 If enabled, the motion of the frames is compared to a reference frame
11129 in the filtered stream, identified by the specified number. The idea
11130 is to compensate all movements in a more-or-less static scene and keep
11131 the camera view absolutely still.
11133 If set to 0, it is disabled. The frames are counted starting from 1.
11136 Show fields and transforms in the resulting frames. It accepts an
11137 integer in the range 0-2. Default value is 0, which disables any
11141 @subsection Examples
11145 Use default values:
11151 Analyze strongly shaky movie and put the results in file
11152 @file{mytransforms.trf}:
11154 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
11158 Visualize the result of internal transformations in the resulting
11161 vidstabdetect=show=1
11165 Analyze a video with medium shakiness using @command{ffmpeg}:
11167 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
11171 @anchor{vidstabtransform}
11172 @section vidstabtransform
11174 Video stabilization/deshaking: pass 2 of 2,
11175 see @ref{vidstabdetect} for pass 1.
11177 Read a file with transform information for each frame and
11178 apply/compensate them. Together with the @ref{vidstabdetect}
11179 filter this can be used to deshake videos. See also
11180 @url{http://public.hronopik.de/vid.stab}. It is important to also use
11181 the @ref{unsharp} filter, see below.
11183 To enable compilation of this filter you need to configure FFmpeg with
11184 @code{--enable-libvidstab}.
11186 @subsection Options
11190 Set path to the file used to read the transforms. Default value is
11191 @file{transforms.trf}.
11194 Set the number of frames (value*2 + 1) used for lowpass filtering the
11195 camera movements. Default value is 10.
11197 For example a number of 10 means that 21 frames are used (10 in the
11198 past and 10 in the future) to smoothen the motion in the video. A
11199 larger value leads to a smoother video, but limits the acceleration of
11200 the camera (pan/tilt movements). 0 is a special case where a static
11201 camera is simulated.
11204 Set the camera path optimization algorithm.
11206 Accepted values are:
11209 gaussian kernel low-pass filter on camera motion (default)
11211 averaging on transformations
11215 Set maximal number of pixels to translate frames. Default value is -1,
11219 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
11220 value is -1, meaning no limit.
11223 Specify how to deal with borders that may be visible due to movement
11226 Available values are:
11229 keep image information from previous frame (default)
11231 fill the border black
11235 Invert transforms if set to 1. Default value is 0.
11238 Consider transforms as relative to previous frame if set to 1,
11239 absolute if set to 0. Default value is 0.
11242 Set percentage to zoom. A positive value will result in a zoom-in
11243 effect, a negative value in a zoom-out effect. Default value is 0 (no
11247 Set optimal zooming to avoid borders.
11249 Accepted values are:
11254 optimal static zoom value is determined (only very strong movements
11255 will lead to visible borders) (default)
11257 optimal adaptive zoom value is determined (no borders will be
11258 visible), see @option{zoomspeed}
11261 Note that the value given at zoom is added to the one calculated here.
11264 Set percent to zoom maximally each frame (enabled when
11265 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
11269 Specify type of interpolation.
11271 Available values are:
11276 linear only horizontal
11278 linear in both directions (default)
11280 cubic in both directions (slow)
11284 Enable virtual tripod mode if set to 1, which is equivalent to
11285 @code{relative=0:smoothing=0}. Default value is 0.
11287 Use also @code{tripod} option of @ref{vidstabdetect}.
11290 Increase log verbosity if set to 1. Also the detected global motions
11291 are written to the temporary file @file{global_motions.trf}. Default
11295 @subsection Examples
11299 Use @command{ffmpeg} for a typical stabilization with default values:
11301 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
11304 Note the use of the @ref{unsharp} filter which is always recommended.
11307 Zoom in a bit more and load transform data from a given file:
11309 vidstabtransform=zoom=5:input="mytransforms.trf"
11313 Smoothen the video even more:
11315 vidstabtransform=smoothing=30
11321 Flip the input video vertically.
11323 For example, to vertically flip a video with @command{ffmpeg}:
11325 ffmpeg -i in.avi -vf "vflip" out.avi
11331 Make or reverse a natural vignetting effect.
11333 The filter accepts the following options:
11337 Set lens angle expression as a number of radians.
11339 The value is clipped in the @code{[0,PI/2]} range.
11341 Default value: @code{"PI/5"}
11345 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
11349 Set forward/backward mode.
11351 Available modes are:
11354 The larger the distance from the central point, the darker the image becomes.
11357 The larger the distance from the central point, the brighter the image becomes.
11358 This can be used to reverse a vignette effect, though there is no automatic
11359 detection to extract the lens @option{angle} and other settings (yet). It can
11360 also be used to create a burning effect.
11363 Default value is @samp{forward}.
11366 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
11368 It accepts the following values:
11371 Evaluate expressions only once during the filter initialization.
11374 Evaluate expressions for each incoming frame. This is way slower than the
11375 @samp{init} mode since it requires all the scalers to be re-computed, but it
11376 allows advanced dynamic expressions.
11379 Default value is @samp{init}.
11382 Set dithering to reduce the circular banding effects. Default is @code{1}
11386 Set vignette aspect. This setting allows one to adjust the shape of the vignette.
11387 Setting this value to the SAR of the input will make a rectangular vignetting
11388 following the dimensions of the video.
11390 Default is @code{1/1}.
11393 @subsection Expressions
11395 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
11396 following parameters.
11401 input width and height
11404 the number of input frame, starting from 0
11407 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
11408 @var{TB} units, NAN if undefined
11411 frame rate of the input video, NAN if the input frame rate is unknown
11414 the PTS (Presentation TimeStamp) of the filtered video frame,
11415 expressed in seconds, NAN if undefined
11418 time base of the input video
11422 @subsection Examples
11426 Apply simple strong vignetting effect:
11432 Make a flickering vignetting:
11434 vignette='PI/4+random(1)*PI/50':eval=frame
11440 Stack input videos vertically.
11442 All streams must be of same pixel format and of same width.
11444 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
11445 to create same output.
11447 The filter accept the following option:
11451 Set number of input streams. Default is 2.
11456 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
11457 Deinterlacing Filter").
11459 Based on the process described by Martin Weston for BBC R&D, and
11460 implemented based on the de-interlace algorithm written by Jim
11461 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
11462 uses filter coefficients calculated by BBC R&D.
11464 There are two sets of filter coefficients, so called "simple":
11465 and "complex". Which set of filter coefficients is used can
11466 be set by passing an optional parameter:
11470 Set the interlacing filter coefficients. Accepts one of the following values:
11474 Simple filter coefficient set.
11476 More-complex filter coefficient set.
11478 Default value is @samp{complex}.
11481 Specify which frames to deinterlace. Accept one of the following values:
11485 Deinterlace all frames,
11487 Only deinterlace frames marked as interlaced.
11490 Default value is @samp{all}.
11494 Video waveform monitor.
11496 The waveform monitor plots color component intensity. By default luminance
11497 only. Each column of the waveform corresponds to a column of pixels in the
11500 It accepts the following options:
11504 Can be either @code{row}, or @code{column}. Default is @code{column}.
11505 In row mode, the graph on the left side represents color component value 0 and
11506 the right side represents value = 255. In column mode, the top side represents
11507 color component value = 0 and bottom side represents value = 255.
11510 Set intensity. Smaller values are useful to find out how many values of the same
11511 luminance are distributed across input rows/columns.
11512 Default value is @code{0.04}. Allowed range is [0, 1].
11515 Set mirroring mode. @code{0} means unmirrored, @code{1} means mirrored.
11516 In mirrored mode, higher values will be represented on the left
11517 side for @code{row} mode and at the top for @code{column} mode. Default is
11518 @code{1} (mirrored).
11522 It accepts the following values:
11525 Presents information identical to that in the @code{parade}, except
11526 that the graphs representing color components are superimposed directly
11529 This display mode makes it easier to spot relative differences or similarities
11530 in overlapping areas of the color components that are supposed to be identical,
11531 such as neutral whites, grays, or blacks.
11534 Display separate graph for the color components side by side in
11535 @code{row} mode or one below the other in @code{column} mode.
11537 Using this display mode makes it easy to spot color casts in the highlights
11538 and shadows of an image, by comparing the contours of the top and the bottom
11539 graphs of each waveform. Since whites, grays, and blacks are characterized
11540 by exactly equal amounts of red, green, and blue, neutral areas of the picture
11541 should display three waveforms of roughly equal width/height. If not, the
11542 correction is easy to perform by making level adjustments the three waveforms.
11544 Default is @code{parade}.
11546 @item components, c
11547 Set which color components to display. Default is 1, which means only luminance
11548 or red color component if input is in RGB colorspace. If is set for example to
11549 7 it will display all 3 (if) available color components.
11554 No envelope, this is default.
11557 Instant envelope, minimum and maximum values presented in graph will be easily
11558 visible even with small @code{step} value.
11561 Hold minimum and maximum values presented in graph across time. This way you
11562 can still spot out of range values without constantly looking at waveforms.
11565 Peak and instant envelope combined together.
11571 No filtering, this is default.
11574 Luma and chroma combined together.
11577 Similar as above, but shows difference between blue and red chroma.
11580 Displays only chroma.
11583 Similar as above, but shows difference between blue and red chroma.
11586 Displays actual color value on waveform.
11591 Apply the xBR high-quality magnification filter which is designed for pixel
11592 art. It follows a set of edge-detection rules, see
11593 @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}.
11595 It accepts the following option:
11599 Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
11600 @code{3xBR} and @code{4} for @code{4xBR}.
11601 Default is @code{3}.
11607 Deinterlace the input video ("yadif" means "yet another deinterlacing
11610 It accepts the following parameters:
11616 The interlacing mode to adopt. It accepts one of the following values:
11619 @item 0, send_frame
11620 Output one frame for each frame.
11621 @item 1, send_field
11622 Output one frame for each field.
11623 @item 2, send_frame_nospatial
11624 Like @code{send_frame}, but it skips the spatial interlacing check.
11625 @item 3, send_field_nospatial
11626 Like @code{send_field}, but it skips the spatial interlacing check.
11629 The default value is @code{send_frame}.
11632 The picture field parity assumed for the input interlaced video. It accepts one
11633 of the following values:
11637 Assume the top field is first.
11639 Assume the bottom field is first.
11641 Enable automatic detection of field parity.
11644 The default value is @code{auto}.
11645 If the interlacing is unknown or the decoder does not export this information,
11646 top field first will be assumed.
11649 Specify which frames to deinterlace. Accept one of the following
11654 Deinterlace all frames.
11655 @item 1, interlaced
11656 Only deinterlace frames marked as interlaced.
11659 The default value is @code{all}.
11664 Apply Zoom & Pan effect.
11666 This filter accepts the following options:
11670 Set the zoom expression. Default is 1.
11674 Set the x and y expression. Default is 0.
11677 Set the duration expression in number of frames.
11678 This sets for how many number of frames effect will last for
11679 single input image.
11682 Set the output image size, default is 'hd720'.
11685 Each expression can contain the following constants:
11704 Output frame count.
11708 Last calculated 'x' and 'y' position from 'x' and 'y' expression
11709 for current input frame.
11713 'x' and 'y' of last output frame of previous input frame or 0 when there was
11714 not yet such frame (first input frame).
11717 Last calculated zoom from 'z' expression for current input frame.
11720 Last calculated zoom of last output frame of previous input frame.
11723 Number of output frames for current input frame. Calculated from 'd' expression
11724 for each input frame.
11727 number of output frames created for previous input frame
11730 Rational number: input width / input height
11733 sample aspect ratio
11736 display aspect ratio
11740 @subsection Examples
11744 Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
11746 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
11750 Zoom-in up to 1.5 and pan always at center of picture:
11752 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
11756 @c man end VIDEO FILTERS
11758 @chapter Video Sources
11759 @c man begin VIDEO SOURCES
11761 Below is a description of the currently available video sources.
11765 Buffer video frames, and make them available to the filter chain.
11767 This source is mainly intended for a programmatic use, in particular
11768 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
11770 It accepts the following parameters:
11775 Specify the size (width and height) of the buffered video frames. For the
11776 syntax of this option, check the
11777 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11780 The input video width.
11783 The input video height.
11786 A string representing the pixel format of the buffered video frames.
11787 It may be a number corresponding to a pixel format, or a pixel format
11791 Specify the timebase assumed by the timestamps of the buffered frames.
11794 Specify the frame rate expected for the video stream.
11796 @item pixel_aspect, sar
11797 The sample (pixel) aspect ratio of the input video.
11800 Specify the optional parameters to be used for the scale filter which
11801 is automatically inserted when an input change is detected in the
11802 input size or format.
11807 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
11810 will instruct the source to accept video frames with size 320x240 and
11811 with format "yuv410p", assuming 1/24 as the timestamps timebase and
11812 square pixels (1:1 sample aspect ratio).
11813 Since the pixel format with name "yuv410p" corresponds to the number 6
11814 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
11815 this example corresponds to:
11817 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
11820 Alternatively, the options can be specified as a flat string, but this
11821 syntax is deprecated:
11823 @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}]
11827 Create a pattern generated by an elementary cellular automaton.
11829 The initial state of the cellular automaton can be defined through the
11830 @option{filename}, and @option{pattern} options. If such options are
11831 not specified an initial state is created randomly.
11833 At each new frame a new row in the video is filled with the result of
11834 the cellular automaton next generation. The behavior when the whole
11835 frame is filled is defined by the @option{scroll} option.
11837 This source accepts the following options:
11841 Read the initial cellular automaton state, i.e. the starting row, from
11842 the specified file.
11843 In the file, each non-whitespace character is considered an alive
11844 cell, a newline will terminate the row, and further characters in the
11845 file will be ignored.
11848 Read the initial cellular automaton state, i.e. the starting row, from
11849 the specified string.
11851 Each non-whitespace character in the string is considered an alive
11852 cell, a newline will terminate the row, and further characters in the
11853 string will be ignored.
11856 Set the video rate, that is the number of frames generated per second.
11859 @item random_fill_ratio, ratio
11860 Set the random fill ratio for the initial cellular automaton row. It
11861 is a floating point number value ranging from 0 to 1, defaults to
11864 This option is ignored when a file or a pattern is specified.
11866 @item random_seed, seed
11867 Set the seed for filling randomly the initial row, must be an integer
11868 included between 0 and UINT32_MAX. If not specified, or if explicitly
11869 set to -1, the filter will try to use a good random seed on a best
11873 Set the cellular automaton rule, it is a number ranging from 0 to 255.
11874 Default value is 110.
11877 Set the size of the output video. For the syntax of this option, check the
11878 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11880 If @option{filename} or @option{pattern} is specified, the size is set
11881 by default to the width of the specified initial state row, and the
11882 height is set to @var{width} * PHI.
11884 If @option{size} is set, it must contain the width of the specified
11885 pattern string, and the specified pattern will be centered in the
11888 If a filename or a pattern string is not specified, the size value
11889 defaults to "320x518" (used for a randomly generated initial state).
11892 If set to 1, scroll the output upward when all the rows in the output
11893 have been already filled. If set to 0, the new generated row will be
11894 written over the top row just after the bottom row is filled.
11897 @item start_full, full
11898 If set to 1, completely fill the output with generated rows before
11899 outputting the first frame.
11900 This is the default behavior, for disabling set the value to 0.
11903 If set to 1, stitch the left and right row edges together.
11904 This is the default behavior, for disabling set the value to 0.
11907 @subsection Examples
11911 Read the initial state from @file{pattern}, and specify an output of
11914 cellauto=f=pattern:s=200x400
11918 Generate a random initial row with a width of 200 cells, with a fill
11921 cellauto=ratio=2/3:s=200x200
11925 Create a pattern generated by rule 18 starting by a single alive cell
11926 centered on an initial row with width 100:
11928 cellauto=p=@@:s=100x400:full=0:rule=18
11932 Specify a more elaborated initial pattern:
11934 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
11939 @section mandelbrot
11941 Generate a Mandelbrot set fractal, and progressively zoom towards the
11942 point specified with @var{start_x} and @var{start_y}.
11944 This source accepts the following options:
11949 Set the terminal pts value. Default value is 400.
11952 Set the terminal scale value.
11953 Must be a floating point value. Default value is 0.3.
11956 Set the inner coloring mode, that is the algorithm used to draw the
11957 Mandelbrot fractal internal region.
11959 It shall assume one of the following values:
11964 Show time until convergence.
11966 Set color based on point closest to the origin of the iterations.
11971 Default value is @var{mincol}.
11974 Set the bailout value. Default value is 10.0.
11977 Set the maximum of iterations performed by the rendering
11978 algorithm. Default value is 7189.
11981 Set outer coloring mode.
11982 It shall assume one of following values:
11984 @item iteration_count
11985 Set iteration cound mode.
11986 @item normalized_iteration_count
11987 set normalized iteration count mode.
11989 Default value is @var{normalized_iteration_count}.
11992 Set frame rate, expressed as number of frames per second. Default
11996 Set frame size. For the syntax of this option, check the "Video
11997 size" section in the ffmpeg-utils manual. Default value is "640x480".
12000 Set the initial scale value. Default value is 3.0.
12003 Set the initial x position. Must be a floating point value between
12004 -100 and 100. Default value is -0.743643887037158704752191506114774.
12007 Set the initial y position. Must be a floating point value between
12008 -100 and 100. Default value is -0.131825904205311970493132056385139.
12013 Generate various test patterns, as generated by the MPlayer test filter.
12015 The size of the generated video is fixed, and is 256x256.
12016 This source is useful in particular for testing encoding features.
12018 This source accepts the following options:
12023 Specify the frame rate of the sourced video, as the number of frames
12024 generated per second. It has to be a string in the format
12025 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
12026 number or a valid video frame rate abbreviation. The default value is
12030 Set the duration of the sourced video. See
12031 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12032 for the accepted syntax.
12034 If not specified, or the expressed duration is negative, the video is
12035 supposed to be generated forever.
12039 Set the number or the name of the test to perform. Supported tests are:
12055 Default value is "all", which will cycle through the list of all tests.
12060 mptestsrc=t=dc_luma
12063 will generate a "dc_luma" test pattern.
12065 @section frei0r_src
12067 Provide a frei0r source.
12069 To enable compilation of this filter you need to install the frei0r
12070 header and configure FFmpeg with @code{--enable-frei0r}.
12072 This source accepts the following parameters:
12077 The size of the video to generate. For the syntax of this option, check the
12078 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12081 The framerate of the generated video. It may be a string of the form
12082 @var{num}/@var{den} or a frame rate abbreviation.
12085 The name to the frei0r source to load. For more information regarding frei0r and
12086 how to set the parameters, read the @ref{frei0r} section in the video filters
12089 @item filter_params
12090 A '|'-separated list of parameters to pass to the frei0r source.
12094 For example, to generate a frei0r partik0l source with size 200x200
12095 and frame rate 10 which is overlaid on the overlay filter main input:
12097 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
12102 Generate a life pattern.
12104 This source is based on a generalization of John Conway's life game.
12106 The sourced input represents a life grid, each pixel represents a cell
12107 which can be in one of two possible states, alive or dead. Every cell
12108 interacts with its eight neighbours, which are the cells that are
12109 horizontally, vertically, or diagonally adjacent.
12111 At each interaction the grid evolves according to the adopted rule,
12112 which specifies the number of neighbor alive cells which will make a
12113 cell stay alive or born. The @option{rule} option allows one to specify
12116 This source accepts the following options:
12120 Set the file from which to read the initial grid state. In the file,
12121 each non-whitespace character is considered an alive cell, and newline
12122 is used to delimit the end of each row.
12124 If this option is not specified, the initial grid is generated
12128 Set the video rate, that is the number of frames generated per second.
12131 @item random_fill_ratio, ratio
12132 Set the random fill ratio for the initial random grid. It is a
12133 floating point number value ranging from 0 to 1, defaults to 1/PHI.
12134 It is ignored when a file is specified.
12136 @item random_seed, seed
12137 Set the seed for filling the initial random grid, must be an integer
12138 included between 0 and UINT32_MAX. If not specified, or if explicitly
12139 set to -1, the filter will try to use a good random seed on a best
12145 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
12146 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
12147 @var{NS} specifies the number of alive neighbor cells which make a
12148 live cell stay alive, and @var{NB} the number of alive neighbor cells
12149 which make a dead cell to become alive (i.e. to "born").
12150 "s" and "b" can be used in place of "S" and "B", respectively.
12152 Alternatively a rule can be specified by an 18-bits integer. The 9
12153 high order bits are used to encode the next cell state if it is alive
12154 for each number of neighbor alive cells, the low order bits specify
12155 the rule for "borning" new cells. Higher order bits encode for an
12156 higher number of neighbor cells.
12157 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
12158 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
12160 Default value is "S23/B3", which is the original Conway's game of life
12161 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
12162 cells, and will born a new cell if there are three alive cells around
12166 Set the size of the output video. For the syntax of this option, check the
12167 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12169 If @option{filename} is specified, the size is set by default to the
12170 same size of the input file. If @option{size} is set, it must contain
12171 the size specified in the input file, and the initial grid defined in
12172 that file is centered in the larger resulting area.
12174 If a filename is not specified, the size value defaults to "320x240"
12175 (used for a randomly generated initial grid).
12178 If set to 1, stitch the left and right grid edges together, and the
12179 top and bottom edges also. Defaults to 1.
12182 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
12183 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
12184 value from 0 to 255.
12187 Set the color of living (or new born) cells.
12190 Set the color of dead cells. If @option{mold} is set, this is the first color
12191 used to represent a dead cell.
12194 Set mold color, for definitely dead and moldy cells.
12196 For the syntax of these 3 color options, check the "Color" section in the
12197 ffmpeg-utils manual.
12200 @subsection Examples
12204 Read a grid from @file{pattern}, and center it on a grid of size
12207 life=f=pattern:s=300x300
12211 Generate a random grid of size 200x200, with a fill ratio of 2/3:
12213 life=ratio=2/3:s=200x200
12217 Specify a custom rule for evolving a randomly generated grid:
12223 Full example with slow death effect (mold) using @command{ffplay}:
12225 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
12232 @anchor{haldclutsrc}
12234 @anchor{rgbtestsrc}
12236 @anchor{smptehdbars}
12238 @section allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
12240 The @code{allrgb} source returns frames of size 4096x4096 of all rgb colors.
12242 The @code{allyuv} source returns frames of size 4096x4096 of all yuv colors.
12244 The @code{color} source provides an uniformly colored input.
12246 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
12247 @ref{haldclut} filter.
12249 The @code{nullsrc} source returns unprocessed video frames. It is
12250 mainly useful to be employed in analysis / debugging tools, or as the
12251 source for filters which ignore the input data.
12253 The @code{rgbtestsrc} source generates an RGB test pattern useful for
12254 detecting RGB vs BGR issues. You should see a red, green and blue
12255 stripe from top to bottom.
12257 The @code{smptebars} source generates a color bars pattern, based on
12258 the SMPTE Engineering Guideline EG 1-1990.
12260 The @code{smptehdbars} source generates a color bars pattern, based on
12261 the SMPTE RP 219-2002.
12263 The @code{testsrc} source generates a test video pattern, showing a
12264 color pattern, a scrolling gradient and a timestamp. This is mainly
12265 intended for testing purposes.
12267 The sources accept the following parameters:
12272 Specify the color of the source, only available in the @code{color}
12273 source. For the syntax of this option, check the "Color" section in the
12274 ffmpeg-utils manual.
12277 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
12278 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
12279 pixels to be used as identity matrix for 3D lookup tables. Each component is
12280 coded on a @code{1/(N*N)} scale.
12283 Specify the size of the sourced video. For the syntax of this option, check the
12284 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12285 The default value is @code{320x240}.
12287 This option is not available with the @code{haldclutsrc} filter.
12290 Specify the frame rate of the sourced video, as the number of frames
12291 generated per second. It has to be a string in the format
12292 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
12293 number or a valid video frame rate abbreviation. The default value is
12297 Set the sample aspect ratio of the sourced video.
12300 Set the duration of the sourced video. See
12301 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12302 for the accepted syntax.
12304 If not specified, or the expressed duration is negative, the video is
12305 supposed to be generated forever.
12308 Set the number of decimals to show in the timestamp, only available in the
12309 @code{testsrc} source.
12311 The displayed timestamp value will correspond to the original
12312 timestamp value multiplied by the power of 10 of the specified
12313 value. Default value is 0.
12316 For example the following:
12318 testsrc=duration=5.3:size=qcif:rate=10
12321 will generate a video with a duration of 5.3 seconds, with size
12322 176x144 and a frame rate of 10 frames per second.
12324 The following graph description will generate a red source
12325 with an opacity of 0.2, with size "qcif" and a frame rate of 10
12328 color=c=red@@0.2:s=qcif:r=10
12331 If the input content is to be ignored, @code{nullsrc} can be used. The
12332 following command generates noise in the luminance plane by employing
12333 the @code{geq} filter:
12335 nullsrc=s=256x256, geq=random(1)*255:128:128
12338 @subsection Commands
12340 The @code{color} source supports the following commands:
12344 Set the color of the created image. Accepts the same syntax of the
12345 corresponding @option{color} option.
12348 @c man end VIDEO SOURCES
12350 @chapter Video Sinks
12351 @c man begin VIDEO SINKS
12353 Below is a description of the currently available video sinks.
12355 @section buffersink
12357 Buffer video frames, and make them available to the end of the filter
12360 This sink is mainly intended for programmatic use, in particular
12361 through the interface defined in @file{libavfilter/buffersink.h}
12362 or the options system.
12364 It accepts a pointer to an AVBufferSinkContext structure, which
12365 defines the incoming buffers' formats, to be passed as the opaque
12366 parameter to @code{avfilter_init_filter} for initialization.
12370 Null video sink: do absolutely nothing with the input video. It is
12371 mainly useful as a template and for use in analysis / debugging
12374 @c man end VIDEO SINKS
12376 @chapter Multimedia Filters
12377 @c man begin MULTIMEDIA FILTERS
12379 Below is a description of the currently available multimedia filters.
12381 @section aphasemeter
12383 Convert input audio to a video output, displaying the audio phase.
12385 The filter accepts the following options:
12389 Set the output frame rate. Default value is @code{25}.
12392 Set the video size for the output. For the syntax of this option, check the
12393 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12394 Default value is @code{800x400}.
12399 Specify the red, green, blue contrast. Default values are @code{2},
12400 @code{7} and @code{1}.
12401 Allowed range is @code{[0, 255]}.
12404 Set color which will be used for drawing median phase. If color is
12405 @code{none} which is default, no median phase value will be drawn.
12408 The filter also exports the frame metadata @code{lavfi.aphasemeter.phase} which
12409 represents mean phase of current audio frame. Value is in range @code{[-1, 1]}.
12410 The @code{-1} means left and right channels are completely out of phase and
12411 @code{1} means channels are in phase.
12413 @section avectorscope
12415 Convert input audio to a video output, representing the audio vector
12418 The filter is used to measure the difference between channels of stereo
12419 audio stream. A monoaural signal, consisting of identical left and right
12420 signal, results in straight vertical line. Any stereo separation is visible
12421 as a deviation from this line, creating a Lissajous figure.
12422 If the straight (or deviation from it) but horizontal line appears this
12423 indicates that the left and right channels are out of phase.
12425 The filter accepts the following options:
12429 Set the vectorscope mode.
12431 Available values are:
12434 Lissajous rotated by 45 degrees.
12437 Same as above but not rotated.
12440 Shape resembling half of circle.
12443 Default value is @samp{lissajous}.
12446 Set the video size for the output. For the syntax of this option, check the
12447 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12448 Default value is @code{400x400}.
12451 Set the output frame rate. Default value is @code{25}.
12457 Specify the red, green, blue and alpha contrast. Default values are @code{40},
12458 @code{160}, @code{80} and @code{255}.
12459 Allowed range is @code{[0, 255]}.
12465 Specify the red, green, blue and alpha fade. Default values are @code{15},
12466 @code{10}, @code{5} and @code{5}.
12467 Allowed range is @code{[0, 255]}.
12470 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
12473 @subsection Examples
12477 Complete example using @command{ffplay}:
12479 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
12480 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
12486 Concatenate audio and video streams, joining them together one after the
12489 The filter works on segments of synchronized video and audio streams. All
12490 segments must have the same number of streams of each type, and that will
12491 also be the number of streams at output.
12493 The filter accepts the following options:
12498 Set the number of segments. Default is 2.
12501 Set the number of output video streams, that is also the number of video
12502 streams in each segment. Default is 1.
12505 Set the number of output audio streams, that is also the number of audio
12506 streams in each segment. Default is 0.
12509 Activate unsafe mode: do not fail if segments have a different format.
12513 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
12514 @var{a} audio outputs.
12516 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
12517 segment, in the same order as the outputs, then the inputs for the second
12520 Related streams do not always have exactly the same duration, for various
12521 reasons including codec frame size or sloppy authoring. For that reason,
12522 related synchronized streams (e.g. a video and its audio track) should be
12523 concatenated at once. The concat filter will use the duration of the longest
12524 stream in each segment (except the last one), and if necessary pad shorter
12525 audio streams with silence.
12527 For this filter to work correctly, all segments must start at timestamp 0.
12529 All corresponding streams must have the same parameters in all segments; the
12530 filtering system will automatically select a common pixel format for video
12531 streams, and a common sample format, sample rate and channel layout for
12532 audio streams, but other settings, such as resolution, must be converted
12533 explicitly by the user.
12535 Different frame rates are acceptable but will result in variable frame rate
12536 at output; be sure to configure the output file to handle it.
12538 @subsection Examples
12542 Concatenate an opening, an episode and an ending, all in bilingual version
12543 (video in stream 0, audio in streams 1 and 2):
12545 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
12546 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
12547 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
12548 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
12552 Concatenate two parts, handling audio and video separately, using the
12553 (a)movie sources, and adjusting the resolution:
12555 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
12556 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
12557 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
12559 Note that a desync will happen at the stitch if the audio and video streams
12560 do not have exactly the same duration in the first file.
12567 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
12568 it unchanged. By default, it logs a message at a frequency of 10Hz with the
12569 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
12570 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
12572 The filter also has a video output (see the @var{video} option) with a real
12573 time graph to observe the loudness evolution. The graphic contains the logged
12574 message mentioned above, so it is not printed anymore when this option is set,
12575 unless the verbose logging is set. The main graphing area contains the
12576 short-term loudness (3 seconds of analysis), and the gauge on the right is for
12577 the momentary loudness (400 milliseconds).
12579 More information about the Loudness Recommendation EBU R128 on
12580 @url{http://tech.ebu.ch/loudness}.
12582 The filter accepts the following options:
12587 Activate the video output. The audio stream is passed unchanged whether this
12588 option is set or no. The video stream will be the first output stream if
12589 activated. Default is @code{0}.
12592 Set the video size. This option is for video only. For the syntax of this
12594 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12595 Default and minimum resolution is @code{640x480}.
12598 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
12599 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
12600 other integer value between this range is allowed.
12603 Set metadata injection. If set to @code{1}, the audio input will be segmented
12604 into 100ms output frames, each of them containing various loudness information
12605 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
12607 Default is @code{0}.
12610 Force the frame logging level.
12612 Available values are:
12615 information logging level
12617 verbose logging level
12620 By default, the logging level is set to @var{info}. If the @option{video} or
12621 the @option{metadata} options are set, it switches to @var{verbose}.
12626 Available modes can be cumulated (the option is a @code{flag} type). Possible
12630 Disable any peak mode (default).
12632 Enable sample-peak mode.
12634 Simple peak mode looking for the higher sample value. It logs a message
12635 for sample-peak (identified by @code{SPK}).
12637 Enable true-peak mode.
12639 If enabled, the peak lookup is done on an over-sampled version of the input
12640 stream for better peak accuracy. It logs a message for true-peak.
12641 (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}).
12642 This mode requires a build with @code{libswresample}.
12647 @subsection Examples
12651 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
12653 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
12657 Run an analysis with @command{ffmpeg}:
12659 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
12663 @section interleave, ainterleave
12665 Temporally interleave frames from several inputs.
12667 @code{interleave} works with video inputs, @code{ainterleave} with audio.
12669 These filters read frames from several inputs and send the oldest
12670 queued frame to the output.
12672 Input streams must have a well defined, monotonically increasing frame
12675 In order to submit one frame to output, these filters need to enqueue
12676 at least one frame for each input, so they cannot work in case one
12677 input is not yet terminated and will not receive incoming frames.
12679 For example consider the case when one input is a @code{select} filter
12680 which always drop input frames. The @code{interleave} filter will keep
12681 reading from that input, but it will never be able to send new frames
12682 to output until the input will send an end-of-stream signal.
12684 Also, depending on inputs synchronization, the filters will drop
12685 frames in case one input receives more frames than the other ones, and
12686 the queue is already filled.
12688 These filters accept the following options:
12692 Set the number of different inputs, it is 2 by default.
12695 @subsection Examples
12699 Interleave frames belonging to different streams using @command{ffmpeg}:
12701 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
12705 Add flickering blur effect:
12707 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
12711 @section perms, aperms
12713 Set read/write permissions for the output frames.
12715 These filters are mainly aimed at developers to test direct path in the
12716 following filter in the filtergraph.
12718 The filters accept the following options:
12722 Select the permissions mode.
12724 It accepts the following values:
12727 Do nothing. This is the default.
12729 Set all the output frames read-only.
12731 Set all the output frames directly writable.
12733 Make the frame read-only if writable, and writable if read-only.
12735 Set each output frame read-only or writable randomly.
12739 Set the seed for the @var{random} mode, must be an integer included between
12740 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
12741 @code{-1}, the filter will try to use a good random seed on a best effort
12745 Note: in case of auto-inserted filter between the permission filter and the
12746 following one, the permission might not be received as expected in that
12747 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
12748 perms/aperms filter can avoid this problem.
12750 @section select, aselect
12752 Select frames to pass in output.
12754 This filter accepts the following options:
12759 Set expression, which is evaluated for each input frame.
12761 If the expression is evaluated to zero, the frame is discarded.
12763 If the evaluation result is negative or NaN, the frame is sent to the
12764 first output; otherwise it is sent to the output with index
12765 @code{ceil(val)-1}, assuming that the input index starts from 0.
12767 For example a value of @code{1.2} corresponds to the output with index
12768 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
12771 Set the number of outputs. The output to which to send the selected
12772 frame is based on the result of the evaluation. Default value is 1.
12775 The expression can contain the following constants:
12779 The (sequential) number of the filtered frame, starting from 0.
12782 The (sequential) number of the selected frame, starting from 0.
12784 @item prev_selected_n
12785 The sequential number of the last selected frame. It's NAN if undefined.
12788 The timebase of the input timestamps.
12791 The PTS (Presentation TimeStamp) of the filtered video frame,
12792 expressed in @var{TB} units. It's NAN if undefined.
12795 The PTS of the filtered video frame,
12796 expressed in seconds. It's NAN if undefined.
12799 The PTS of the previously filtered video frame. It's NAN if undefined.
12801 @item prev_selected_pts
12802 The PTS of the last previously filtered video frame. It's NAN if undefined.
12804 @item prev_selected_t
12805 The PTS of the last previously selected video frame. It's NAN if undefined.
12808 The PTS of the first video frame in the video. It's NAN if undefined.
12811 The time of the first video frame in the video. It's NAN if undefined.
12813 @item pict_type @emph{(video only)}
12814 The type of the filtered frame. It can assume one of the following
12826 @item interlace_type @emph{(video only)}
12827 The frame interlace type. It can assume one of the following values:
12830 The frame is progressive (not interlaced).
12832 The frame is top-field-first.
12834 The frame is bottom-field-first.
12837 @item consumed_sample_n @emph{(audio only)}
12838 the number of selected samples before the current frame
12840 @item samples_n @emph{(audio only)}
12841 the number of samples in the current frame
12843 @item sample_rate @emph{(audio only)}
12844 the input sample rate
12847 This is 1 if the filtered frame is a key-frame, 0 otherwise.
12850 the position in the file of the filtered frame, -1 if the information
12851 is not available (e.g. for synthetic video)
12853 @item scene @emph{(video only)}
12854 value between 0 and 1 to indicate a new scene; a low value reflects a low
12855 probability for the current frame to introduce a new scene, while a higher
12856 value means the current frame is more likely to be one (see the example below)
12860 The default value of the select expression is "1".
12862 @subsection Examples
12866 Select all frames in input:
12871 The example above is the same as:
12883 Select only I-frames:
12885 select='eq(pict_type\,I)'
12889 Select one frame every 100:
12891 select='not(mod(n\,100))'
12895 Select only frames contained in the 10-20 time interval:
12897 select=between(t\,10\,20)
12901 Select only I frames contained in the 10-20 time interval:
12903 select=between(t\,10\,20)*eq(pict_type\,I)
12907 Select frames with a minimum distance of 10 seconds:
12909 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
12913 Use aselect to select only audio frames with samples number > 100:
12915 aselect='gt(samples_n\,100)'
12919 Create a mosaic of the first scenes:
12921 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
12924 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
12928 Send even and odd frames to separate outputs, and compose them:
12930 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
12934 @section sendcmd, asendcmd
12936 Send commands to filters in the filtergraph.
12938 These filters read commands to be sent to other filters in the
12941 @code{sendcmd} must be inserted between two video filters,
12942 @code{asendcmd} must be inserted between two audio filters, but apart
12943 from that they act the same way.
12945 The specification of commands can be provided in the filter arguments
12946 with the @var{commands} option, or in a file specified by the
12947 @var{filename} option.
12949 These filters accept the following options:
12952 Set the commands to be read and sent to the other filters.
12954 Set the filename of the commands to be read and sent to the other
12958 @subsection Commands syntax
12960 A commands description consists of a sequence of interval
12961 specifications, comprising a list of commands to be executed when a
12962 particular event related to that interval occurs. The occurring event
12963 is typically the current frame time entering or leaving a given time
12966 An interval is specified by the following syntax:
12968 @var{START}[-@var{END}] @var{COMMANDS};
12971 The time interval is specified by the @var{START} and @var{END} times.
12972 @var{END} is optional and defaults to the maximum time.
12974 The current frame time is considered within the specified interval if
12975 it is included in the interval [@var{START}, @var{END}), that is when
12976 the time is greater or equal to @var{START} and is lesser than
12979 @var{COMMANDS} consists of a sequence of one or more command
12980 specifications, separated by ",", relating to that interval. The
12981 syntax of a command specification is given by:
12983 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
12986 @var{FLAGS} is optional and specifies the type of events relating to
12987 the time interval which enable sending the specified command, and must
12988 be a non-null sequence of identifier flags separated by "+" or "|" and
12989 enclosed between "[" and "]".
12991 The following flags are recognized:
12994 The command is sent when the current frame timestamp enters the
12995 specified interval. In other words, the command is sent when the
12996 previous frame timestamp was not in the given interval, and the
13000 The command is sent when the current frame timestamp leaves the
13001 specified interval. In other words, the command is sent when the
13002 previous frame timestamp was in the given interval, and the
13006 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
13009 @var{TARGET} specifies the target of the command, usually the name of
13010 the filter class or a specific filter instance name.
13012 @var{COMMAND} specifies the name of the command for the target filter.
13014 @var{ARG} is optional and specifies the optional list of argument for
13015 the given @var{COMMAND}.
13017 Between one interval specification and another, whitespaces, or
13018 sequences of characters starting with @code{#} until the end of line,
13019 are ignored and can be used to annotate comments.
13021 A simplified BNF description of the commands specification syntax
13024 @var{COMMAND_FLAG} ::= "enter" | "leave"
13025 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
13026 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
13027 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
13028 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
13029 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
13032 @subsection Examples
13036 Specify audio tempo change at second 4:
13038 asendcmd=c='4.0 atempo tempo 1.5',atempo
13042 Specify a list of drawtext and hue commands in a file.
13044 # show text in the interval 5-10
13045 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
13046 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
13048 # desaturate the image in the interval 15-20
13049 15.0-20.0 [enter] hue s 0,
13050 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
13052 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
13054 # apply an exponential saturation fade-out effect, starting from time 25
13055 25 [enter] hue s exp(25-t)
13058 A filtergraph allowing to read and process the above command list
13059 stored in a file @file{test.cmd}, can be specified with:
13061 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
13066 @section setpts, asetpts
13068 Change the PTS (presentation timestamp) of the input frames.
13070 @code{setpts} works on video frames, @code{asetpts} on audio frames.
13072 This filter accepts the following options:
13077 The expression which is evaluated for each frame to construct its timestamp.
13081 The expression is evaluated through the eval API and can contain the following
13086 frame rate, only defined for constant frame-rate video
13089 The presentation timestamp in input
13092 The count of the input frame for video or the number of consumed samples,
13093 not including the current frame for audio, starting from 0.
13095 @item NB_CONSUMED_SAMPLES
13096 The number of consumed samples, not including the current frame (only
13099 @item NB_SAMPLES, S
13100 The number of samples in the current frame (only audio)
13102 @item SAMPLE_RATE, SR
13103 The audio sample rate.
13106 The PTS of the first frame.
13109 the time in seconds of the first frame
13112 State whether the current frame is interlaced.
13115 the time in seconds of the current frame
13118 original position in the file of the frame, or undefined if undefined
13119 for the current frame
13122 The previous input PTS.
13125 previous input time in seconds
13128 The previous output PTS.
13131 previous output time in seconds
13134 The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
13138 The wallclock (RTC) time at the start of the movie in microseconds.
13141 The timebase of the input timestamps.
13145 @subsection Examples
13149 Start counting PTS from zero
13151 setpts=PTS-STARTPTS
13155 Apply fast motion effect:
13161 Apply slow motion effect:
13167 Set fixed rate of 25 frames per second:
13173 Set fixed rate 25 fps with some jitter:
13175 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
13179 Apply an offset of 10 seconds to the input PTS:
13185 Generate timestamps from a "live source" and rebase onto the current timebase:
13187 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
13191 Generate timestamps by counting samples:
13198 @section settb, asettb
13200 Set the timebase to use for the output frames timestamps.
13201 It is mainly useful for testing timebase configuration.
13203 It accepts the following parameters:
13208 The expression which is evaluated into the output timebase.
13212 The value for @option{tb} is an arithmetic expression representing a
13213 rational. The expression can contain the constants "AVTB" (the default
13214 timebase), "intb" (the input timebase) and "sr" (the sample rate,
13215 audio only). Default value is "intb".
13217 @subsection Examples
13221 Set the timebase to 1/25:
13227 Set the timebase to 1/10:
13233 Set the timebase to 1001/1000:
13239 Set the timebase to 2*intb:
13245 Set the default timebase value:
13252 Convert input audio to a video output representing
13253 frequency spectrum logarithmically (using constant Q transform with
13254 Brown-Puckette algorithm), with musical tone scale, from E0 to D#10 (10 octaves).
13256 The filter accepts the following options:
13260 Specify transform volume (multiplier) expression. The expression can contain
13263 @item frequency, freq, f
13264 the frequency where transform is evaluated
13265 @item timeclamp, tc
13266 value of timeclamp option
13270 @item a_weighting(f)
13271 A-weighting of equal loudness
13272 @item b_weighting(f)
13273 B-weighting of equal loudness
13274 @item c_weighting(f)
13275 C-weighting of equal loudness
13277 Default value is @code{16}.
13280 Specify transform length expression. The expression can contain variables:
13282 @item frequency, freq, f
13283 the frequency where transform is evaluated
13284 @item timeclamp, tc
13285 value of timeclamp option
13287 Default value is @code{384/f*tc/(384/f+tc)}.
13290 Specify the transform timeclamp. At low frequency, there is trade-off between
13291 accuracy in time domain and frequency domain. If timeclamp is lower,
13292 event in time domain is represented more accurately (such as fast bass drum),
13293 otherwise event in frequency domain is represented more accurately
13294 (such as bass guitar). Acceptable value is [0.1, 1.0]. Default value is @code{0.17}.
13297 Specify the transform coeffclamp. If coeffclamp is lower, transform is
13298 more accurate, otherwise transform is faster. Acceptable value is [0.1, 10.0].
13299 Default value is @code{1.0}.
13302 Specify gamma. Lower gamma makes the spectrum more contrast, higher gamma
13303 makes the spectrum having more range. Acceptable value is [1.0, 7.0].
13304 Default value is @code{3.0}.
13307 Specify gamma of bargraph. Acceptable value is [1.0, 7.0].
13308 Default value is @code{1.0}.
13311 Specify font file for use with freetype. If not specified, use embedded font.
13314 Specify font color expression. This is arithmetic expression that should return
13315 integer value 0xRRGGBB. The expression can contain variables:
13317 @item frequency, freq, f
13318 the frequency where transform is evaluated
13319 @item timeclamp, tc
13320 value of timeclamp option
13325 midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
13326 @item r(x), g(x), b(x)
13327 red, green, and blue value of intensity x
13329 Default value is @code{st(0, (midi(f)-59.5)/12);
13330 st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
13331 r(1-ld(1)) + b(ld(1))}
13334 If set to 1 (the default), the video size is 1920x1080 (full HD),
13335 if set to 0, the video size is 960x540. Use this option to make CPU usage lower.
13338 Specify video fps. Default value is @code{25}.
13341 Specify number of transform per frame, so there are fps*count transforms
13342 per second. Note that audio data rate must be divisible by fps*count.
13343 Default value is @code{6}.
13347 @subsection Examples
13351 Playing audio while showing the spectrum:
13353 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
13357 Same as above, but with frame rate 30 fps:
13359 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
13363 Playing at 960x540 and lower CPU usage:
13365 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fullhd=0:count=3 [out0]'
13369 A1 and its harmonics: A1, A2, (near)E3, A3:
13371 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),
13372 asplit[a][out1]; [a] showcqt [out0]'
13376 Same as above, but with more accuracy in frequency domain (and slower):
13378 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),
13379 asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
13383 B-weighting of equal loudness
13385 volume=16*b_weighting(f)
13391 tlength=100/f*tc/(100/f+tc)
13395 Custom fontcolor, C-note is colored green, others are colored blue
13397 fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))'
13401 Custom gamma, now spectrum is linear to the amplitude.
13410 Convert input audio to video output representing the audio power spectrum.
13411 Audio amplitude is on Y-axis while frequency is on X-axis.
13413 The filter accepts the following options:
13417 Specify size of video. For the syntax of this option, check the
13418 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13419 Default is @code{1024x512}.
13423 This set how each frequency bin will be represented.
13425 It accepts the following values:
13431 Default is @code{bar}.
13434 Set amplitude scale.
13436 It accepts the following values:
13450 Default is @code{log}.
13453 Set frequency scale.
13455 It accepts the following values:
13464 Reverse logarithmic scale.
13466 Default is @code{lin}.
13471 It accepts the following values:
13487 Default is @code{w2048}
13490 Set windowing function.
13492 It accepts the following values:
13509 Default is @code{hanning}.
13512 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
13513 which means optimal overlap for selected window function will be picked.
13516 Set time averaging. Setting this to 0 will display current maximal peaks.
13517 Default is @code{1}, which means time averaging is disabled.
13520 Specify list of colors separated by space or by '|' which will be used to
13521 draw channel frequencies. Unrecognized or missing colors will be replaced
13525 @section showspectrum
13527 Convert input audio to a video output, representing the audio frequency
13530 The filter accepts the following options:
13534 Specify the video size for the output. For the syntax of this option, check the
13535 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13536 Default value is @code{640x512}.
13539 Specify how the spectrum should slide along the window.
13541 It accepts the following values:
13544 the samples start again on the left when they reach the right
13546 the samples scroll from right to left
13548 frames are only produced when the samples reach the right
13551 Default value is @code{replace}.
13554 Specify display mode.
13556 It accepts the following values:
13559 all channels are displayed in the same row
13561 all channels are displayed in separate rows
13564 Default value is @samp{combined}.
13567 Specify display color mode.
13569 It accepts the following values:
13572 each channel is displayed in a separate color
13574 each channel is is displayed using the same color scheme
13577 Default value is @samp{channel}.
13580 Specify scale used for calculating intensity color values.
13582 It accepts the following values:
13587 square root, default
13594 Default value is @samp{sqrt}.
13597 Set saturation modifier for displayed colors. Negative values provide
13598 alternative color scheme. @code{0} is no saturation at all.
13599 Saturation must be in [-10.0, 10.0] range.
13600 Default value is @code{1}.
13603 Set window function.
13605 It accepts the following values:
13608 No samples pre-processing (do not expect this to be faster)
13617 Default value is @code{hann}.
13620 The usage is very similar to the showwaves filter; see the examples in that
13623 @subsection Examples
13627 Large window with logarithmic color scaling:
13629 showspectrum=s=1280x480:scale=log
13633 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
13635 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
13636 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
13640 @section showvolume
13642 Convert input audio volume to a video output.
13644 The filter accepts the following options:
13651 Set border width, allowed range is [0, 5]. Default is 1.
13654 Set channel width, allowed range is [40, 1080]. Default is 400.
13657 Set channel height, allowed range is [1, 100]. Default is 20.
13660 Set fade, allowed range is [1, 255]. Default is 20.
13663 Set volume color expression.
13665 The expression can use the following variables:
13669 Current max volume of channel in dB.
13672 Current channel number, starting from 0.
13676 If set, displays channel names. Default is enabled.
13681 Convert input audio to a video output, representing the samples waves.
13683 The filter accepts the following options:
13687 Specify the video size for the output. For the syntax of this option, check the
13688 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13689 Default value is @code{600x240}.
13694 Available values are:
13697 Draw a point for each sample.
13700 Draw a vertical line for each sample.
13703 Draw a point for each sample and a line between them.
13706 Draw a centered vertical line for each sample.
13709 Default value is @code{point}.
13712 Set the number of samples which are printed on the same column. A
13713 larger value will decrease the frame rate. Must be a positive
13714 integer. This option can be set only if the value for @var{rate}
13715 is not explicitly specified.
13718 Set the (approximate) output frame rate. This is done by setting the
13719 option @var{n}. Default value is "25".
13721 @item split_channels
13722 Set if channels should be drawn separately or overlap. Default value is 0.
13726 @subsection Examples
13730 Output the input file audio and the corresponding video representation
13733 amovie=a.mp3,asplit[out0],showwaves[out1]
13737 Create a synthetic signal and show it with showwaves, forcing a
13738 frame rate of 30 frames per second:
13740 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
13744 @section showwavespic
13746 Convert input audio to a single video frame, representing the samples waves.
13748 The filter accepts the following options:
13752 Specify the video size for the output. For the syntax of this option, check the
13753 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13754 Default value is @code{600x240}.
13756 @item split_channels
13757 Set if channels should be drawn separately or overlap. Default value is 0.
13760 @subsection Examples
13764 Extract a channel split representation of the wave form of a whole audio track
13765 in a 1024x800 picture using @command{ffmpeg}:
13767 ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
13771 @section split, asplit
13773 Split input into several identical outputs.
13775 @code{asplit} works with audio input, @code{split} with video.
13777 The filter accepts a single parameter which specifies the number of outputs. If
13778 unspecified, it defaults to 2.
13780 @subsection Examples
13784 Create two separate outputs from the same input:
13786 [in] split [out0][out1]
13790 To create 3 or more outputs, you need to specify the number of
13793 [in] asplit=3 [out0][out1][out2]
13797 Create two separate outputs from the same input, one cropped and
13800 [in] split [splitout1][splitout2];
13801 [splitout1] crop=100:100:0:0 [cropout];
13802 [splitout2] pad=200:200:100:100 [padout];
13806 Create 5 copies of the input audio with @command{ffmpeg}:
13808 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
13814 Receive commands sent through a libzmq client, and forward them to
13815 filters in the filtergraph.
13817 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
13818 must be inserted between two video filters, @code{azmq} between two
13821 To enable these filters you need to install the libzmq library and
13822 headers and configure FFmpeg with @code{--enable-libzmq}.
13824 For more information about libzmq see:
13825 @url{http://www.zeromq.org/}
13827 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
13828 receives messages sent through a network interface defined by the
13829 @option{bind_address} option.
13831 The received message must be in the form:
13833 @var{TARGET} @var{COMMAND} [@var{ARG}]
13836 @var{TARGET} specifies the target of the command, usually the name of
13837 the filter class or a specific filter instance name.
13839 @var{COMMAND} specifies the name of the command for the target filter.
13841 @var{ARG} is optional and specifies the optional argument list for the
13842 given @var{COMMAND}.
13844 Upon reception, the message is processed and the corresponding command
13845 is injected into the filtergraph. Depending on the result, the filter
13846 will send a reply to the client, adopting the format:
13848 @var{ERROR_CODE} @var{ERROR_REASON}
13852 @var{MESSAGE} is optional.
13854 @subsection Examples
13856 Look at @file{tools/zmqsend} for an example of a zmq client which can
13857 be used to send commands processed by these filters.
13859 Consider the following filtergraph generated by @command{ffplay}
13861 ffplay -dumpgraph 1 -f lavfi "
13862 color=s=100x100:c=red [l];
13863 color=s=100x100:c=blue [r];
13864 nullsrc=s=200x100, zmq [bg];
13865 [bg][l] overlay [bg+l];
13866 [bg+l][r] overlay=x=100 "
13869 To change the color of the left side of the video, the following
13870 command can be used:
13872 echo Parsed_color_0 c yellow | tools/zmqsend
13875 To change the right side:
13877 echo Parsed_color_1 c pink | tools/zmqsend
13880 @c man end MULTIMEDIA FILTERS
13882 @chapter Multimedia Sources
13883 @c man begin MULTIMEDIA SOURCES
13885 Below is a description of the currently available multimedia sources.
13889 This is the same as @ref{movie} source, except it selects an audio
13895 Read audio and/or video stream(s) from a movie container.
13897 It accepts the following parameters:
13901 The name of the resource to read (not necessarily a file; it can also be a
13902 device or a stream accessed through some protocol).
13904 @item format_name, f
13905 Specifies the format assumed for the movie to read, and can be either
13906 the name of a container or an input device. If not specified, the
13907 format is guessed from @var{movie_name} or by probing.
13909 @item seek_point, sp
13910 Specifies the seek point in seconds. The frames will be output
13911 starting from this seek point. The parameter is evaluated with
13912 @code{av_strtod}, so the numerical value may be suffixed by an IS
13913 postfix. The default value is "0".
13916 Specifies the streams to read. Several streams can be specified,
13917 separated by "+". The source will then have as many outputs, in the
13918 same order. The syntax is explained in the ``Stream specifiers''
13919 section in the ffmpeg manual. Two special names, "dv" and "da" specify
13920 respectively the default (best suited) video and audio stream. Default
13921 is "dv", or "da" if the filter is called as "amovie".
13923 @item stream_index, si
13924 Specifies the index of the video stream to read. If the value is -1,
13925 the most suitable video stream will be automatically selected. The default
13926 value is "-1". Deprecated. If the filter is called "amovie", it will select
13927 audio instead of video.
13930 Specifies how many times to read the stream in sequence.
13931 If the value is less than 1, the stream will be read again and again.
13932 Default value is "1".
13934 Note that when the movie is looped the source timestamps are not
13935 changed, so it will generate non monotonically increasing timestamps.
13938 It allows overlaying a second video on top of the main input of
13939 a filtergraph, as shown in this graph:
13941 input -----------> deltapts0 --> overlay --> output
13944 movie --> scale--> deltapts1 -------+
13946 @subsection Examples
13950 Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
13951 on top of the input labelled "in":
13953 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
13954 [in] setpts=PTS-STARTPTS [main];
13955 [main][over] overlay=16:16 [out]
13959 Read from a video4linux2 device, and overlay it on top of the input
13962 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
13963 [in] setpts=PTS-STARTPTS [main];
13964 [main][over] overlay=16:16 [out]
13968 Read the first video stream and the audio stream with id 0x81 from
13969 dvd.vob; the video is connected to the pad named "video" and the audio is
13970 connected to the pad named "audio":
13972 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
13976 @c man end MULTIMEDIA SOURCES