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.
2295 @section sidechaincompress
2297 This filter acts like normal compressor but has the ability to compress
2298 detected signal using second input signal.
2299 It needs two input streams and returns one output stream.
2300 First input stream will be processed depending on second stream signal.
2301 The filtered signal then can be filtered with other filters in later stages of
2302 processing. See @ref{pan} and @ref{amerge} filter.
2304 The filter accepts the following options:
2308 If a signal of second stream raises above this level it will affect the gain
2309 reduction of first stream.
2310 By default is 0.125. Range is between 0.00097563 and 1.
2313 Set a ratio about which the signal is reduced. 1:2 means that if the level
2314 raised 4dB above the threshold, it will be only 2dB above after the reduction.
2315 Default is 2. Range is between 1 and 20.
2318 Amount of milliseconds the signal has to rise above the threshold before gain
2319 reduction starts. Default is 20. Range is between 0.01 and 2000.
2322 Amount of milliseconds the signal has to fall bellow the threshold before
2323 reduction is decreased again. Default is 250. Range is between 0.01 and 9000.
2326 Set the amount by how much signal will be amplified after processing.
2327 Default is 2. Range is from 1 and 64.
2330 Curve the sharp knee around the threshold to enter gain reduction more softly.
2331 Default is 2.82843. Range is between 1 and 8.
2334 Choose if the @code{average} level between all channels of side-chain stream
2335 or the louder(@code{maximum}) channel of side-chain stream affects the
2336 reduction. Default is @code{average}.
2339 Should the exact signal be taken in case of @code{peak} or an RMS one in case
2340 of @code{rms}. Default is @code{rms} which is mainly smoother.
2343 @subsection Examples
2347 Full ffmpeg example taking 2 audio inputs, 1st input to be compressed
2348 depending on the signal of 2nd input and later compressed signal to be
2349 merged with 2nd input:
2351 ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
2355 @section silencedetect
2357 Detect silence in an audio stream.
2359 This filter logs a message when it detects that the input audio volume is less
2360 or equal to a noise tolerance value for a duration greater or equal to the
2361 minimum detected noise duration.
2363 The printed times and duration are expressed in seconds.
2365 The filter accepts the following options:
2369 Set silence duration until notification (default is 2 seconds).
2372 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
2373 specified value) or amplitude ratio. Default is -60dB, or 0.001.
2376 @subsection Examples
2380 Detect 5 seconds of silence with -50dB noise tolerance:
2382 silencedetect=n=-50dB:d=5
2386 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
2387 tolerance in @file{silence.mp3}:
2389 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
2393 @section silenceremove
2395 Remove silence from the beginning, middle or end of the audio.
2397 The filter accepts the following options:
2401 This value is used to indicate if audio should be trimmed at beginning of
2402 the audio. A value of zero indicates no silence should be trimmed from the
2403 beginning. When specifying a non-zero value, it trims audio up until it
2404 finds non-silence. Normally, when trimming silence from beginning of audio
2405 the @var{start_periods} will be @code{1} but it can be increased to higher
2406 values to trim all audio up to specific count of non-silence periods.
2407 Default value is @code{0}.
2409 @item start_duration
2410 Specify the amount of time that non-silence must be detected before it stops
2411 trimming audio. By increasing the duration, bursts of noises can be treated
2412 as silence and trimmed off. Default value is @code{0}.
2414 @item start_threshold
2415 This indicates what sample value should be treated as silence. For digital
2416 audio, a value of @code{0} may be fine but for audio recorded from analog,
2417 you may wish to increase the value to account for background noise.
2418 Can be specified in dB (in case "dB" is appended to the specified value)
2419 or amplitude ratio. Default value is @code{0}.
2422 Set the count for trimming silence from the end of audio.
2423 To remove silence from the middle of a file, specify a @var{stop_periods}
2424 that is negative. This value is then treated as a positive value and is
2425 used to indicate the effect should restart processing as specified by
2426 @var{start_periods}, making it suitable for removing periods of silence
2427 in the middle of the audio.
2428 Default value is @code{0}.
2431 Specify a duration of silence that must exist before audio is not copied any
2432 more. By specifying a higher duration, silence that is wanted can be left in
2434 Default value is @code{0}.
2436 @item stop_threshold
2437 This is the same as @option{start_threshold} but for trimming silence from
2439 Can be specified in dB (in case "dB" is appended to the specified value)
2440 or amplitude ratio. Default value is @code{0}.
2443 This indicate that @var{stop_duration} length of audio should be left intact
2444 at the beginning of each period of silence.
2445 For example, if you want to remove long pauses between words but do not want
2446 to remove the pauses completely. Default value is @code{0}.
2450 @subsection Examples
2454 The following example shows how this filter can be used to start a recording
2455 that does not contain the delay at the start which usually occurs between
2456 pressing the record button and the start of the performance:
2458 silenceremove=1:5:0.02
2462 @section stereotools
2464 This filter has some handy utilities to manage stereo signals, for converting
2465 M/S stereo recordings to L/R signal while having control over the parameters
2466 or spreading the stereo image of master track.
2468 The filter accepts the following options:
2472 Set input level before filtering for both channels. Defaults is 1.
2473 Allowed range is from 0.015625 to 64.
2476 Set output level after filtering for both channels. Defaults is 1.
2477 Allowed range is from 0.015625 to 64.
2480 Set input balance between both channels. Default is 0.
2481 Allowed range is from -1 to 1.
2484 Set output balance between both channels. Default is 0.
2485 Allowed range is from -1 to 1.
2488 Enable softclipping. Results in analog distortion instead of harsh digital 0dB
2489 clipping. Disabled by default.
2492 Mute the left channel. Disabled by default.
2495 Mute the right channel. Disabled by default.
2498 Change the phase of the left channel. Disabled by default.
2501 Change the phase of the right channel. Disabled by default.
2504 Set stereo mode. Available values are:
2508 Left/Right to Left/Right, this is default.
2511 Left/Right to Mid/Side.
2514 Mid/Side to Left/Right.
2517 Left/Right to Left/Left.
2520 Left/Right to Right/Right.
2523 Left/Right to Left + Right.
2526 Left/Right to Right/Left.
2530 Set level of side signal. Default is 1.
2531 Allowed range is from 0.015625 to 64.
2534 Set balance of side signal. Default is 0.
2535 Allowed range is from -1 to 1.
2538 Set level of the middle signal. Default is 1.
2539 Allowed range is from 0.015625 to 64.
2542 Set middle signal pan. Default is 0. Allowed range is from -1 to 1.
2545 Set stereo base between mono and inversed channels. Default is 0.
2546 Allowed range is from -1 to 1.
2549 Set delay in milliseconds how much to delay left from right channel and
2550 vice versa. Default is 0. Allowed range is from -20 to 20.
2553 Set S/C level. Default is 1. Allowed range is from 1 to 100.
2556 Set the stereo phase in degrees. Default is 0. Allowed range is from 0 to 360.
2559 @section stereowiden
2561 This filter enhance the stereo effect by suppressing signal common to both
2562 channels and by delaying the signal of left into right and vice versa,
2563 thereby widening the stereo effect.
2565 The filter accepts the following options:
2569 Time in milliseconds of the delay of left signal into right and vice versa.
2570 Default is 20 milliseconds.
2573 Amount of gain in delayed signal into right and vice versa. Gives a delay
2574 effect of left signal in right output and vice versa which gives widening
2575 effect. Default is 0.3.
2578 Cross feed of left into right with inverted phase. This helps in suppressing
2579 the mono. If the value is 1 it will cancel all the signal common to both
2580 channels. Default is 0.3.
2583 Set level of input signal of original channel. Default is 0.8.
2588 Boost or cut treble (upper) frequencies of the audio using a two-pole
2589 shelving filter with a response similar to that of a standard
2590 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
2592 The filter accepts the following options:
2596 Give the gain at whichever is the lower of ~22 kHz and the
2597 Nyquist frequency. Its useful range is about -20 (for a large cut)
2598 to +20 (for a large boost). Beware of clipping when using a positive gain.
2601 Set the filter's central frequency and so can be used
2602 to extend or reduce the frequency range to be boosted or cut.
2603 The default value is @code{3000} Hz.
2606 Set method to specify band-width of filter.
2619 Determine how steep is the filter's shelf transition.
2624 Sinusoidal amplitude modulation.
2626 The filter accepts the following options:
2630 Modulation frequency in Hertz. Modulation frequencies in the subharmonic range
2631 (20 Hz or lower) will result in a tremolo effect.
2632 This filter may also be used as a ring modulator by specifying
2633 a modulation frequency higher than 20 Hz.
2634 Range is 0.1 - 20000.0. Default value is 5.0 Hz.
2637 Depth of modulation as a percentage. Range is 0.0 - 1.0.
2638 Default value is 0.5.
2643 Adjust the input audio volume.
2645 It accepts the following parameters:
2649 Set audio volume expression.
2651 Output values are clipped to the maximum value.
2653 The output audio volume is given by the relation:
2655 @var{output_volume} = @var{volume} * @var{input_volume}
2658 The default value for @var{volume} is "1.0".
2661 This parameter represents the mathematical precision.
2663 It determines which input sample formats will be allowed, which affects the
2664 precision of the volume scaling.
2668 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
2670 32-bit floating-point; this limits input sample format to FLT. (default)
2672 64-bit floating-point; this limits input sample format to DBL.
2676 Choose the behaviour on encountering ReplayGain side data in input frames.
2680 Remove ReplayGain side data, ignoring its contents (the default).
2683 Ignore ReplayGain side data, but leave it in the frame.
2686 Prefer the track gain, if present.
2689 Prefer the album gain, if present.
2692 @item replaygain_preamp
2693 Pre-amplification gain in dB to apply to the selected replaygain gain.
2695 Default value for @var{replaygain_preamp} is 0.0.
2698 Set when the volume expression is evaluated.
2700 It accepts the following values:
2703 only evaluate expression once during the filter initialization, or
2704 when the @samp{volume} command is sent
2707 evaluate expression for each incoming frame
2710 Default value is @samp{once}.
2713 The volume expression can contain the following parameters.
2717 frame number (starting at zero)
2720 @item nb_consumed_samples
2721 number of samples consumed by the filter
2723 number of samples in the current frame
2725 original frame position in the file
2731 PTS at start of stream
2733 time at start of stream
2739 last set volume value
2742 Note that when @option{eval} is set to @samp{once} only the
2743 @var{sample_rate} and @var{tb} variables are available, all other
2744 variables will evaluate to NAN.
2746 @subsection Commands
2748 This filter supports the following commands:
2751 Modify the volume expression.
2752 The command accepts the same syntax of the corresponding option.
2754 If the specified expression is not valid, it is kept at its current
2756 @item replaygain_noclip
2757 Prevent clipping by limiting the gain applied.
2759 Default value for @var{replaygain_noclip} is 1.
2763 @subsection Examples
2767 Halve the input audio volume:
2771 volume=volume=-6.0206dB
2774 In all the above example the named key for @option{volume} can be
2775 omitted, for example like in:
2781 Increase input audio power by 6 decibels using fixed-point precision:
2783 volume=volume=6dB:precision=fixed
2787 Fade volume after time 10 with an annihilation period of 5 seconds:
2789 volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
2793 @section volumedetect
2795 Detect the volume of the input video.
2797 The filter has no parameters. The input is not modified. Statistics about
2798 the volume will be printed in the log when the input stream end is reached.
2800 In particular it will show the mean volume (root mean square), maximum
2801 volume (on a per-sample basis), and the beginning of a histogram of the
2802 registered volume values (from the maximum value to a cumulated 1/1000 of
2805 All volumes are in decibels relative to the maximum PCM value.
2807 @subsection Examples
2809 Here is an excerpt of the output:
2811 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
2812 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
2813 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
2814 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
2815 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
2816 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
2817 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
2818 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
2819 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
2825 The mean square energy is approximately -27 dB, or 10^-2.7.
2827 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
2829 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
2832 In other words, raising the volume by +4 dB does not cause any clipping,
2833 raising it by +5 dB causes clipping for 6 samples, etc.
2835 @c man end AUDIO FILTERS
2837 @chapter Audio Sources
2838 @c man begin AUDIO SOURCES
2840 Below is a description of the currently available audio sources.
2844 Buffer audio frames, and make them available to the filter chain.
2846 This source is mainly intended for a programmatic use, in particular
2847 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
2849 It accepts the following parameters:
2853 The timebase which will be used for timestamps of submitted frames. It must be
2854 either a floating-point number or in @var{numerator}/@var{denominator} form.
2857 The sample rate of the incoming audio buffers.
2860 The sample format of the incoming audio buffers.
2861 Either a sample format name or its corresponding integer representation from
2862 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
2864 @item channel_layout
2865 The channel layout of the incoming audio buffers.
2866 Either a channel layout name from channel_layout_map in
2867 @file{libavutil/channel_layout.c} or its corresponding integer representation
2868 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
2871 The number of channels of the incoming audio buffers.
2872 If both @var{channels} and @var{channel_layout} are specified, then they
2877 @subsection Examples
2880 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
2883 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
2884 Since the sample format with name "s16p" corresponds to the number
2885 6 and the "stereo" channel layout corresponds to the value 0x3, this is
2888 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
2893 Generate an audio signal specified by an expression.
2895 This source accepts in input one or more expressions (one for each
2896 channel), which are evaluated and used to generate a corresponding
2899 This source accepts the following options:
2903 Set the '|'-separated expressions list for each separate channel. In case the
2904 @option{channel_layout} option is not specified, the selected channel layout
2905 depends on the number of provided expressions. Otherwise the last
2906 specified expression is applied to the remaining output channels.
2908 @item channel_layout, c
2909 Set the channel layout. The number of channels in the specified layout
2910 must be equal to the number of specified expressions.
2913 Set the minimum duration of the sourced audio. See
2914 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
2915 for the accepted syntax.
2916 Note that the resulting duration may be greater than the specified
2917 duration, as the generated audio is always cut at the end of a
2920 If not specified, or the expressed duration is negative, the audio is
2921 supposed to be generated forever.
2924 Set the number of samples per channel per each output frame,
2927 @item sample_rate, s
2928 Specify the sample rate, default to 44100.
2931 Each expression in @var{exprs} can contain the following constants:
2935 number of the evaluated sample, starting from 0
2938 time of the evaluated sample expressed in seconds, starting from 0
2945 @subsection Examples
2955 Generate a sin signal with frequency of 440 Hz, set sample rate to
2958 aevalsrc="sin(440*2*PI*t):s=8000"
2962 Generate a two channels signal, specify the channel layout (Front
2963 Center + Back Center) explicitly:
2965 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
2969 Generate white noise:
2971 aevalsrc="-2+random(0)"
2975 Generate an amplitude modulated signal:
2977 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
2981 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
2983 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
2990 The null audio source, return unprocessed audio frames. It is mainly useful
2991 as a template and to be employed in analysis / debugging tools, or as
2992 the source for filters which ignore the input data (for example the sox
2995 This source accepts the following options:
2999 @item channel_layout, cl
3001 Specifies the channel layout, and can be either an integer or a string
3002 representing a channel layout. The default value of @var{channel_layout}
3005 Check the channel_layout_map definition in
3006 @file{libavutil/channel_layout.c} for the mapping between strings and
3007 channel layout values.
3009 @item sample_rate, r
3010 Specifies the sample rate, and defaults to 44100.
3013 Set the number of samples per requested frames.
3017 @subsection Examples
3021 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
3023 anullsrc=r=48000:cl=4
3027 Do the same operation with a more obvious syntax:
3029 anullsrc=r=48000:cl=mono
3033 All the parameters need to be explicitly defined.
3037 Synthesize a voice utterance using the libflite library.
3039 To enable compilation of this filter you need to configure FFmpeg with
3040 @code{--enable-libflite}.
3042 Note that the flite library is not thread-safe.
3044 The filter accepts the following options:
3049 If set to 1, list the names of the available voices and exit
3050 immediately. Default value is 0.
3053 Set the maximum number of samples per frame. Default value is 512.
3056 Set the filename containing the text to speak.
3059 Set the text to speak.
3062 Set the voice to use for the speech synthesis. Default value is
3063 @code{kal}. See also the @var{list_voices} option.
3066 @subsection Examples
3070 Read from file @file{speech.txt}, and synthesize the text using the
3071 standard flite voice:
3073 flite=textfile=speech.txt
3077 Read the specified text selecting the @code{slt} voice:
3079 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3083 Input text to ffmpeg:
3085 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
3089 Make @file{ffplay} speak the specified text, using @code{flite} and
3090 the @code{lavfi} device:
3092 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
3096 For more information about libflite, check:
3097 @url{http://www.speech.cs.cmu.edu/flite/}
3101 Generate an audio signal made of a sine wave with amplitude 1/8.
3103 The audio signal is bit-exact.
3105 The filter accepts the following options:
3110 Set the carrier frequency. Default is 440 Hz.
3112 @item beep_factor, b
3113 Enable a periodic beep every second with frequency @var{beep_factor} times
3114 the carrier frequency. Default is 0, meaning the beep is disabled.
3116 @item sample_rate, r
3117 Specify the sample rate, default is 44100.
3120 Specify the duration of the generated audio stream.
3122 @item samples_per_frame
3123 Set the number of samples per output frame.
3125 The expression can contain the following constants:
3129 The (sequential) number of the output audio frame, starting from 0.
3132 The PTS (Presentation TimeStamp) of the output audio frame,
3133 expressed in @var{TB} units.
3136 The PTS of the output audio frame, expressed in seconds.
3139 The timebase of the output audio frames.
3142 Default is @code{1024}.
3145 @subsection Examples
3150 Generate a simple 440 Hz sine wave:
3156 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
3160 sine=frequency=220:beep_factor=4:duration=5
3164 Generate a 1 kHz sine wave following @code{1602,1601,1602,1601,1602} NTSC
3167 sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
3171 @c man end AUDIO SOURCES
3173 @chapter Audio Sinks
3174 @c man begin AUDIO SINKS
3176 Below is a description of the currently available audio sinks.
3178 @section abuffersink
3180 Buffer audio frames, and make them available to the end of filter chain.
3182 This sink is mainly intended for programmatic use, in particular
3183 through the interface defined in @file{libavfilter/buffersink.h}
3184 or the options system.
3186 It accepts a pointer to an AVABufferSinkContext structure, which
3187 defines the incoming buffers' formats, to be passed as the opaque
3188 parameter to @code{avfilter_init_filter} for initialization.
3191 Null audio sink; do absolutely nothing with the input audio. It is
3192 mainly useful as a template and for use in analysis / debugging
3195 @c man end AUDIO SINKS
3197 @chapter Video Filters
3198 @c man begin VIDEO FILTERS
3200 When you configure your FFmpeg build, you can disable any of the
3201 existing filters using @code{--disable-filters}.
3202 The configure output will show the video filters included in your
3205 Below is a description of the currently available video filters.
3207 @section alphaextract
3209 Extract the alpha component from the input as a grayscale video. This
3210 is especially useful with the @var{alphamerge} filter.
3214 Add or replace the alpha component of the primary input with the
3215 grayscale value of a second input. This is intended for use with
3216 @var{alphaextract} to allow the transmission or storage of frame
3217 sequences that have alpha in a format that doesn't support an alpha
3220 For example, to reconstruct full frames from a normal YUV-encoded video
3221 and a separate video created with @var{alphaextract}, you might use:
3223 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
3226 Since this filter is designed for reconstruction, it operates on frame
3227 sequences without considering timestamps, and terminates when either
3228 input reaches end of stream. This will cause problems if your encoding
3229 pipeline drops frames. If you're trying to apply an image as an
3230 overlay to a video stream, consider the @var{overlay} filter instead.
3234 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
3235 and libavformat to work. On the other hand, it is limited to ASS (Advanced
3236 Substation Alpha) subtitles files.
3238 This filter accepts the following option in addition to the common options from
3239 the @ref{subtitles} filter:
3243 Set the shaping engine
3245 Available values are:
3248 The default libass shaping engine, which is the best available.
3250 Fast, font-agnostic shaper that can do only substitutions
3252 Slower shaper using OpenType for substitutions and positioning
3255 The default is @code{auto}.
3259 Apply an Adaptive Temporal Averaging Denoiser to the video input.
3261 The filter accepts the following options:
3265 Set threshold A for 1st plane. Default is 0.02.
3266 Valid range is 0 to 0.3.
3269 Set threshold B for 1st plane. Default is 0.04.
3270 Valid range is 0 to 5.
3273 Set threshold A for 2nd plane. Default is 0.02.
3274 Valid range is 0 to 0.3.
3277 Set threshold B for 2nd plane. Default is 0.04.
3278 Valid range is 0 to 5.
3281 Set threshold A for 3rd plane. Default is 0.02.
3282 Valid range is 0 to 0.3.
3285 Set threshold B for 3rd plane. Default is 0.04.
3286 Valid range is 0 to 5.
3288 Threshold A is designed to react on abrupt changes in the input signal and
3289 threshold B is designed to react on continuous changes in the input signal.
3292 Set number of frames filter will use for averaging. Default is 33. Must be odd
3293 number in range [5, 129].
3298 Compute the bounding box for the non-black pixels in the input frame
3301 This filter computes the bounding box containing all the pixels with a
3302 luminance value greater than the minimum allowed value.
3303 The parameters describing the bounding box are printed on the filter
3306 The filter accepts the following option:
3310 Set the minimal luminance value. Default is @code{16}.
3313 @section blackdetect
3315 Detect video intervals that are (almost) completely black. Can be
3316 useful to detect chapter transitions, commercials, or invalid
3317 recordings. Output lines contains the time for the start, end and
3318 duration of the detected black interval expressed in seconds.
3320 In order to display the output lines, you need to set the loglevel at
3321 least to the AV_LOG_INFO value.
3323 The filter accepts the following options:
3326 @item black_min_duration, d
3327 Set the minimum detected black duration expressed in seconds. It must
3328 be a non-negative floating point number.
3330 Default value is 2.0.
3332 @item picture_black_ratio_th, pic_th
3333 Set the threshold for considering a picture "black".
3334 Express the minimum value for the ratio:
3336 @var{nb_black_pixels} / @var{nb_pixels}
3339 for which a picture is considered black.
3340 Default value is 0.98.
3342 @item pixel_black_th, pix_th
3343 Set the threshold for considering a pixel "black".
3345 The threshold expresses the maximum pixel luminance value for which a
3346 pixel is considered "black". The provided value is scaled according to
3347 the following equation:
3349 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
3352 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
3353 the input video format, the range is [0-255] for YUV full-range
3354 formats and [16-235] for YUV non full-range formats.
3356 Default value is 0.10.
3359 The following example sets the maximum pixel threshold to the minimum
3360 value, and detects only black intervals of 2 or more seconds:
3362 blackdetect=d=2:pix_th=0.00
3367 Detect frames that are (almost) completely black. Can be useful to
3368 detect chapter transitions or commercials. Output lines consist of
3369 the frame number of the detected frame, the percentage of blackness,
3370 the position in the file if known or -1 and the timestamp in seconds.
3372 In order to display the output lines, you need to set the loglevel at
3373 least to the AV_LOG_INFO value.
3375 It accepts the following parameters:
3380 The percentage of the pixels that have to be below the threshold; it defaults to
3383 @item threshold, thresh
3384 The threshold below which a pixel value is considered black; it defaults to
3389 @section blend, tblend
3391 Blend two video frames into each other.
3393 The @code{blend} filter takes two input streams and outputs one
3394 stream, the first input is the "top" layer and second input is
3395 "bottom" layer. Output terminates when shortest input terminates.
3397 The @code{tblend} (time blend) filter takes two consecutive frames
3398 from one single stream, and outputs the result obtained by blending
3399 the new frame on top of the old frame.
3401 A description of the accepted options follows.
3409 Set blend mode for specific pixel component or all pixel components in case
3410 of @var{all_mode}. Default value is @code{normal}.
3412 Available values for component modes are:
3449 Set blend opacity for specific pixel component or all pixel components in case
3450 of @var{all_opacity}. Only used in combination with pixel component blend modes.
3457 Set blend expression for specific pixel component or all pixel components in case
3458 of @var{all_expr}. Note that related mode options will be ignored if those are set.
3460 The expressions can use the following variables:
3464 The sequential number of the filtered frame, starting from @code{0}.
3468 the coordinates of the current sample
3472 the width and height of currently filtered plane
3476 Width and height scale depending on the currently filtered plane. It is the
3477 ratio between the corresponding luma plane number of pixels and the current
3478 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3479 @code{0.5,0.5} for chroma planes.
3482 Time of the current frame, expressed in seconds.
3485 Value of pixel component at current location for first video frame (top layer).
3488 Value of pixel component at current location for second video frame (bottom layer).
3492 Force termination when the shortest input terminates. Default is
3493 @code{0}. This option is only defined for the @code{blend} filter.
3496 Continue applying the last bottom frame after the end of the stream. A value of
3497 @code{0} disable the filter after the last frame of the bottom layer is reached.
3498 Default is @code{1}. This option is only defined for the @code{blend} filter.
3501 @subsection Examples
3505 Apply transition from bottom layer to top layer in first 10 seconds:
3507 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
3511 Apply 1x1 checkerboard effect:
3513 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
3517 Apply uncover left effect:
3519 blend=all_expr='if(gte(N*SW+X,W),A,B)'
3523 Apply uncover down effect:
3525 blend=all_expr='if(gte(Y-N*SH,0),A,B)'
3529 Apply uncover up-left effect:
3531 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
3535 Display differences between the current and the previous frame:
3537 tblend=all_mode=difference128
3543 Apply a boxblur algorithm to the input video.
3545 It accepts the following parameters:
3549 @item luma_radius, lr
3550 @item luma_power, lp
3551 @item chroma_radius, cr
3552 @item chroma_power, cp
3553 @item alpha_radius, ar
3554 @item alpha_power, ap
3558 A description of the accepted options follows.
3561 @item luma_radius, lr
3562 @item chroma_radius, cr
3563 @item alpha_radius, ar
3564 Set an expression for the box radius in pixels used for blurring the
3565 corresponding input plane.
3567 The radius value must be a non-negative number, and must not be
3568 greater than the value of the expression @code{min(w,h)/2} for the
3569 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
3572 Default value for @option{luma_radius} is "2". If not specified,
3573 @option{chroma_radius} and @option{alpha_radius} default to the
3574 corresponding value set for @option{luma_radius}.
3576 The expressions can contain the following constants:
3580 The input width and height in pixels.
3584 The input chroma image width and height in pixels.
3588 The horizontal and vertical chroma subsample values. For example, for the
3589 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
3592 @item luma_power, lp
3593 @item chroma_power, cp
3594 @item alpha_power, ap
3595 Specify how many times the boxblur filter is applied to the
3596 corresponding plane.
3598 Default value for @option{luma_power} is 2. If not specified,
3599 @option{chroma_power} and @option{alpha_power} default to the
3600 corresponding value set for @option{luma_power}.
3602 A value of 0 will disable the effect.
3605 @subsection Examples
3609 Apply a boxblur filter with the luma, chroma, and alpha radii
3612 boxblur=luma_radius=2:luma_power=1
3617 Set the luma radius to 2, and alpha and chroma radius to 0:
3619 boxblur=2:1:cr=0:ar=0
3623 Set the luma and chroma radii to a fraction of the video dimension:
3625 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
3631 Visualize information exported by some codecs.
3633 Some codecs can export information through frames using side-data or other
3634 means. For example, some MPEG based codecs export motion vectors through the
3635 @var{export_mvs} flag in the codec @option{flags2} option.
3637 The filter accepts the following option:
3641 Set motion vectors to visualize.
3643 Available flags for @var{mv} are:
3647 forward predicted MVs of P-frames
3649 forward predicted MVs of B-frames
3651 backward predicted MVs of B-frames
3655 @subsection Examples
3659 Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}:
3661 ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb
3665 @section colorbalance
3666 Modify intensity of primary colors (red, green and blue) of input frames.
3668 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
3669 regions for the red-cyan, green-magenta or blue-yellow balance.
3671 A positive adjustment value shifts the balance towards the primary color, a negative
3672 value towards the complementary color.
3674 The filter accepts the following options:
3680 Adjust red, green and blue shadows (darkest pixels).
3685 Adjust red, green and blue midtones (medium pixels).
3690 Adjust red, green and blue highlights (brightest pixels).
3692 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3695 @subsection Examples
3699 Add red color cast to shadows:
3706 RGB colorspace color keying.
3708 The filter accepts the following options:
3712 The color which will be replaced with transparency.
3715 Similarity percentage with the key color.
3717 0.01 matches only the exact key color, while 1.0 matches everything.
3722 0.0 makes pixels either fully transparent, or not transparent at all.
3724 Higher values result in semi-transparent pixels, with a higher transparency
3725 the more similar the pixels color is to the key color.
3728 @subsection Examples
3732 Make every green pixel in the input image transparent:
3734 ffmpeg -i input.png -vf colorkey=green out.png
3738 Overlay a greenscreen-video on top of a static background image.
3740 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
3744 @section colorlevels
3746 Adjust video input frames using levels.
3748 The filter accepts the following options:
3755 Adjust red, green, blue and alpha input black point.
3756 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
3762 Adjust red, green, blue and alpha input white point.
3763 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{1}.
3765 Input levels are used to lighten highlights (bright tones), darken shadows
3766 (dark tones), change the balance of bright and dark tones.
3772 Adjust red, green, blue and alpha output black point.
3773 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{0}.
3779 Adjust red, green, blue and alpha output white point.
3780 Allowed ranges for options are @code{[0, 1.0]}. Defaults are @code{1}.
3782 Output levels allows manual selection of a constrained output level range.
3785 @subsection Examples
3789 Make video output darker:
3791 colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
3797 colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
3801 Make video output lighter:
3803 colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
3807 Increase brightness:
3809 colorlevels=romin=0.5:gomin=0.5:bomin=0.5
3813 @section colorchannelmixer
3815 Adjust video input frames by re-mixing color channels.
3817 This filter modifies a color channel by adding the values associated to
3818 the other channels of the same pixels. For example if the value to
3819 modify is red, the output value will be:
3821 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
3824 The filter accepts the following options:
3831 Adjust contribution of input red, green, blue and alpha channels for output red channel.
3832 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
3838 Adjust contribution of input red, green, blue and alpha channels for output green channel.
3839 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
3845 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
3846 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
3852 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
3853 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
3855 Allowed ranges for options are @code{[-2.0, 2.0]}.
3858 @subsection Examples
3862 Convert source to grayscale:
3864 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
3867 Simulate sepia tones:
3869 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
3873 @section colormatrix
3875 Convert color matrix.
3877 The filter accepts the following options:
3882 Specify the source and destination color matrix. Both values must be
3885 The accepted values are:
3901 For example to convert from BT.601 to SMPTE-240M, use the command:
3903 colormatrix=bt601:smpte240m
3908 Copy the input source unchanged to the output. This is mainly useful for
3913 Crop the input video to given dimensions.
3915 It accepts the following parameters:
3919 The width of the output video. It defaults to @code{iw}.
3920 This expression is evaluated only once during the filter
3921 configuration, or when the @samp{w} or @samp{out_w} command is sent.
3924 The height of the output video. It defaults to @code{ih}.
3925 This expression is evaluated only once during the filter
3926 configuration, or when the @samp{h} or @samp{out_h} command is sent.
3929 The horizontal position, in the input video, of the left edge of the output
3930 video. It defaults to @code{(in_w-out_w)/2}.
3931 This expression is evaluated per-frame.
3934 The vertical position, in the input video, of the top edge of the output video.
3935 It defaults to @code{(in_h-out_h)/2}.
3936 This expression is evaluated per-frame.
3939 If set to 1 will force the output display aspect ratio
3940 to be the same of the input, by changing the output sample aspect
3941 ratio. It defaults to 0.
3944 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
3945 expressions containing the following constants:
3950 The computed values for @var{x} and @var{y}. They are evaluated for
3955 The input width and height.
3959 These are the same as @var{in_w} and @var{in_h}.
3963 The output (cropped) width and height.
3967 These are the same as @var{out_w} and @var{out_h}.
3970 same as @var{iw} / @var{ih}
3973 input sample aspect ratio
3976 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3980 horizontal and vertical chroma subsample values. For example for the
3981 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3984 The number of the input frame, starting from 0.
3987 the position in the file of the input frame, NAN if unknown
3990 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
3994 The expression for @var{out_w} may depend on the value of @var{out_h},
3995 and the expression for @var{out_h} may depend on @var{out_w}, but they
3996 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
3997 evaluated after @var{out_w} and @var{out_h}.
3999 The @var{x} and @var{y} parameters specify the expressions for the
4000 position of the top-left corner of the output (non-cropped) area. They
4001 are evaluated for each frame. If the evaluated value is not valid, it
4002 is approximated to the nearest valid value.
4004 The expression for @var{x} may depend on @var{y}, and the expression
4005 for @var{y} may depend on @var{x}.
4007 @subsection Examples
4011 Crop area with size 100x100 at position (12,34).
4016 Using named options, the example above becomes:
4018 crop=w=100:h=100:x=12:y=34
4022 Crop the central input area with size 100x100:
4028 Crop the central input area with size 2/3 of the input video:
4030 crop=2/3*in_w:2/3*in_h
4034 Crop the input video central square:
4041 Delimit the rectangle with the top-left corner placed at position
4042 100:100 and the right-bottom corner corresponding to the right-bottom
4043 corner of the input image.
4045 crop=in_w-100:in_h-100:100:100
4049 Crop 10 pixels from the left and right borders, and 20 pixels from
4050 the top and bottom borders
4052 crop=in_w-2*10:in_h-2*20
4056 Keep only the bottom right quarter of the input image:
4058 crop=in_w/2:in_h/2:in_w/2:in_h/2
4062 Crop height for getting Greek harmony:
4064 crop=in_w:1/PHI*in_w
4068 Apply trembling effect:
4070 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)
4074 Apply erratic camera effect depending on timestamp:
4076 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)"
4080 Set x depending on the value of y:
4082 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
4086 @subsection Commands
4088 This filter supports the following commands:
4094 Set width/height of the output video and the horizontal/vertical position
4096 The command accepts the same syntax of the corresponding option.
4098 If the specified expression is not valid, it is kept at its current
4104 Auto-detect the crop size.
4106 It calculates the necessary cropping parameters and prints the
4107 recommended parameters via the logging system. The detected dimensions
4108 correspond to the non-black area of the input video.
4110 It accepts the following parameters:
4115 Set higher black value threshold, which can be optionally specified
4116 from nothing (0) to everything (255 for 8bit based formats). An intensity
4117 value greater to the set value is considered non-black. It defaults to 24.
4118 You can also specify a value between 0.0 and 1.0 which will be scaled depending
4119 on the bitdepth of the pixel format.
4122 The value which the width/height should be divisible by. It defaults to
4123 16. The offset is automatically adjusted to center the video. Use 2 to
4124 get only even dimensions (needed for 4:2:2 video). 16 is best when
4125 encoding to most video codecs.
4127 @item reset_count, reset
4128 Set the counter that determines after how many frames cropdetect will
4129 reset the previously detected largest video area and start over to
4130 detect the current optimal crop area. Default value is 0.
4132 This can be useful when channel logos distort the video area. 0
4133 indicates 'never reset', and returns the largest area encountered during
4140 Apply color adjustments using curves.
4142 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
4143 component (red, green and blue) has its values defined by @var{N} key points
4144 tied from each other using a smooth curve. The x-axis represents the pixel
4145 values from the input frame, and the y-axis the new pixel values to be set for
4148 By default, a component curve is defined by the two points @var{(0;0)} and
4149 @var{(1;1)}. This creates a straight line where each original pixel value is
4150 "adjusted" to its own value, which means no change to the image.
4152 The filter allows you to redefine these two points and add some more. A new
4153 curve (using a natural cubic spline interpolation) will be define to pass
4154 smoothly through all these new coordinates. The new defined points needs to be
4155 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
4156 be in the @var{[0;1]} interval. If the computed curves happened to go outside
4157 the vector spaces, the values will be clipped accordingly.
4159 If there is no key point defined in @code{x=0}, the filter will automatically
4160 insert a @var{(0;0)} point. In the same way, if there is no key point defined
4161 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
4163 The filter accepts the following options:
4167 Select one of the available color presets. This option can be used in addition
4168 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
4169 options takes priority on the preset values.
4170 Available presets are:
4173 @item color_negative
4176 @item increase_contrast
4178 @item linear_contrast
4179 @item medium_contrast
4181 @item strong_contrast
4184 Default is @code{none}.
4186 Set the master key points. These points will define a second pass mapping. It
4187 is sometimes called a "luminance" or "value" mapping. It can be used with
4188 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
4189 post-processing LUT.
4191 Set the key points for the red component.
4193 Set the key points for the green component.
4195 Set the key points for the blue component.
4197 Set the key points for all components (not including master).
4198 Can be used in addition to the other key points component
4199 options. In this case, the unset component(s) will fallback on this
4200 @option{all} setting.
4202 Specify a Photoshop curves file (@code{.acv}) to import the settings from.
4205 To avoid some filtergraph syntax conflicts, each key points list need to be
4206 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
4208 @subsection Examples
4212 Increase slightly the middle level of blue:
4214 curves=blue='0.5/0.58'
4220 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
4222 Here we obtain the following coordinates for each components:
4225 @code{(0;0.11) (0.42;0.51) (1;0.95)}
4227 @code{(0;0) (0.50;0.48) (1;1)}
4229 @code{(0;0.22) (0.49;0.44) (1;0.80)}
4233 The previous example can also be achieved with the associated built-in preset:
4235 curves=preset=vintage
4245 Use a Photoshop preset and redefine the points of the green component:
4247 curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'
4253 Denoise frames using 2D DCT (frequency domain filtering).
4255 This filter is not designed for real time.
4257 The filter accepts the following options:
4261 Set the noise sigma constant.
4263 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
4264 coefficient (absolute value) below this threshold with be dropped.
4266 If you need a more advanced filtering, see @option{expr}.
4268 Default is @code{0}.
4271 Set number overlapping pixels for each block. Since the filter can be slow, you
4272 may want to reduce this value, at the cost of a less effective filter and the
4273 risk of various artefacts.
4275 If the overlapping value doesn't permit processing the whole input width or
4276 height, a warning will be displayed and according borders won't be denoised.
4278 Default value is @var{blocksize}-1, which is the best possible setting.
4281 Set the coefficient factor expression.
4283 For each coefficient of a DCT block, this expression will be evaluated as a
4284 multiplier value for the coefficient.
4286 If this is option is set, the @option{sigma} option will be ignored.
4288 The absolute value of the coefficient can be accessed through the @var{c}
4292 Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the
4293 @var{blocksize}, which is the width and height of the processed blocks.
4295 The default value is @var{3} (8x8) and can be raised to @var{4} for a
4296 @var{blocksize} of 16x16. Note that changing this setting has huge consequences
4297 on the speed processing. Also, a larger block size does not necessarily means a
4301 @subsection Examples
4303 Apply a denoise with a @option{sigma} of @code{4.5}:
4308 The same operation can be achieved using the expression system:
4310 dctdnoiz=e='gte(c, 4.5*3)'
4313 Violent denoise using a block size of @code{16x16}:
4320 Remove banding artifacts from input video.
4321 It works by replacing banded pixels with average value of referenced pixels.
4323 The filter accepts the following options:
4330 Set banding detection threshold for each plane. Default is 0.02.
4331 Valid range is 0.00003 to 0.5.
4332 If difference between current pixel and reference pixel is less than threshold,
4333 it will be considered as banded.
4336 Banding detection range in pixels. Default is 16. If positive, random number
4337 in range 0 to set value will be used. If negative, exact absolute value
4339 The range defines square of four pixels around current pixel.
4342 Set direction in radians from which four pixel will be compared. If positive,
4343 random direction from 0 to set direction will be picked. If negative, exact of
4344 absolute value will be picked. For example direction 0, -PI or -2*PI radians
4345 will pick only pixels on same row and -PI/2 will pick only pixels on same
4349 If enabled, current pixel is compared with average value of all four
4350 surrounding pixels. The default is enabled. If disabled current pixel is
4351 compared with all four surrounding pixels. The pixel is considered banded
4352 if only all four differences with surrounding pixels are less than threshold.
4358 Drop duplicated frames at regular intervals.
4360 The filter accepts the following options:
4364 Set the number of frames from which one will be dropped. Setting this to
4365 @var{N} means one frame in every batch of @var{N} frames will be dropped.
4366 Default is @code{5}.
4369 Set the threshold for duplicate detection. If the difference metric for a frame
4370 is less than or equal to this value, then it is declared as duplicate. Default
4374 Set scene change threshold. Default is @code{15}.
4378 Set the size of the x and y-axis blocks used during metric calculations.
4379 Larger blocks give better noise suppression, but also give worse detection of
4380 small movements. Must be a power of two. Default is @code{32}.
4383 Mark main input as a pre-processed input and activate clean source input
4384 stream. This allows the input to be pre-processed with various filters to help
4385 the metrics calculation while keeping the frame selection lossless. When set to
4386 @code{1}, the first stream is for the pre-processed input, and the second
4387 stream is the clean source from where the kept frames are chosen. Default is
4391 Set whether or not chroma is considered in the metric calculations. Default is
4397 Apply deflate effect to the video.
4399 This filter replaces the pixel by the local(3x3) average by taking into account
4400 only values lower than the pixel.
4402 It accepts the following options:
4409 Allows to limit the maximum change for each plane, default is 65535.
4410 If 0, plane will remain unchanged.
4415 Remove judder produced by partially interlaced telecined content.
4417 Judder can be introduced, for instance, by @ref{pullup} filter. If the original
4418 source was partially telecined content then the output of @code{pullup,dejudder}
4419 will have a variable frame rate. May change the recorded frame rate of the
4420 container. Aside from that change, this filter will not affect constant frame
4423 The option available in this filter is:
4427 Specify the length of the window over which the judder repeats.
4429 Accepts any integer greater than 1. Useful values are:
4433 If the original was telecined from 24 to 30 fps (Film to NTSC).
4436 If the original was telecined from 25 to 30 fps (PAL to NTSC).
4439 If a mixture of the two.
4442 The default is @samp{4}.
4447 Suppress a TV station logo by a simple interpolation of the surrounding
4448 pixels. Just set a rectangle covering the logo and watch it disappear
4449 (and sometimes something even uglier appear - your mileage may vary).
4451 It accepts the following parameters:
4456 Specify the top left corner coordinates of the logo. They must be
4461 Specify the width and height of the logo to clear. They must be
4465 Specify the thickness of the fuzzy edge of the rectangle (added to
4466 @var{w} and @var{h}). The default value is 4.
4469 When set to 1, a green rectangle is drawn on the screen to simplify
4470 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
4471 The default value is 0.
4473 The rectangle is drawn on the outermost pixels which will be (partly)
4474 replaced with interpolated values. The values of the next pixels
4475 immediately outside this rectangle in each direction will be used to
4476 compute the interpolated pixel values inside the rectangle.
4480 @subsection Examples
4484 Set a rectangle covering the area with top left corner coordinates 0,0
4485 and size 100x77, and a band of size 10:
4487 delogo=x=0:y=0:w=100:h=77:band=10
4494 Attempt to fix small changes in horizontal and/or vertical shift. This
4495 filter helps remove camera shake from hand-holding a camera, bumping a
4496 tripod, moving on a vehicle, etc.
4498 The filter accepts the following options:
4506 Specify a rectangular area where to limit the search for motion
4508 If desired the search for motion vectors can be limited to a
4509 rectangular area of the frame defined by its top left corner, width
4510 and height. These parameters have the same meaning as the drawbox
4511 filter which can be used to visualise the position of the bounding
4514 This is useful when simultaneous movement of subjects within the frame
4515 might be confused for camera motion by the motion vector search.
4517 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
4518 then the full frame is used. This allows later options to be set
4519 without specifying the bounding box for the motion vector search.
4521 Default - search the whole frame.
4525 Specify the maximum extent of movement in x and y directions in the
4526 range 0-64 pixels. Default 16.
4529 Specify how to generate pixels to fill blanks at the edge of the
4530 frame. Available values are:
4533 Fill zeroes at blank locations
4535 Original image at blank locations
4537 Extruded edge value at blank locations
4539 Mirrored edge at blank locations
4541 Default value is @samp{mirror}.
4544 Specify the blocksize to use for motion search. Range 4-128 pixels,
4548 Specify the contrast threshold for blocks. Only blocks with more than
4549 the specified contrast (difference between darkest and lightest
4550 pixels) will be considered. Range 1-255, default 125.
4553 Specify the search strategy. Available values are:
4556 Set exhaustive search
4558 Set less exhaustive search.
4560 Default value is @samp{exhaustive}.
4563 If set then a detailed log of the motion search is written to the
4567 If set to 1, specify using OpenCL capabilities, only available if
4568 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
4574 Apply an exact inverse of the telecine operation. It requires a predefined
4575 pattern specified using the pattern option which must be the same as that passed
4576 to the telecine filter.
4578 This filter accepts the following options:
4587 The default value is @code{top}.
4591 A string of numbers representing the pulldown pattern you wish to apply.
4592 The default value is @code{23}.
4595 A number representing position of the first frame with respect to the telecine
4596 pattern. This is to be used if the stream is cut. The default value is @code{0}.
4601 Apply dilation effect to the video.
4603 This filter replaces the pixel by the local(3x3) maximum.
4605 It accepts the following options:
4612 Allows to limit the maximum change for each plane, default is 65535.
4613 If 0, plane will remain unchanged.
4616 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
4619 Flags to local 3x3 coordinates maps like this:
4628 Draw a colored box on the input image.
4630 It accepts the following parameters:
4635 The expressions which specify the top left corner coordinates of the box. It defaults to 0.
4639 The expressions which specify the width and height of the box; if 0 they are interpreted as
4640 the input width and height. It defaults to 0.
4643 Specify the color of the box to write. For the general syntax of this option,
4644 check the "Color" section in the ffmpeg-utils manual. If the special
4645 value @code{invert} is used, the box edge color is the same as the
4646 video with inverted luma.
4649 The expression which sets the thickness of the box edge. Default value is @code{3}.
4651 See below for the list of accepted constants.
4654 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4655 following constants:
4659 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4663 horizontal and vertical chroma subsample values. For example for the
4664 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4668 The input width and height.
4671 The input sample aspect ratio.
4675 The x and y offset coordinates where the box is drawn.
4679 The width and height of the drawn box.
4682 The thickness of the drawn box.
4684 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
4685 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
4689 @subsection Examples
4693 Draw a black box around the edge of the input image:
4699 Draw a box with color red and an opacity of 50%:
4701 drawbox=10:20:200:60:red@@0.5
4704 The previous example can be specified as:
4706 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
4710 Fill the box with pink color:
4712 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
4716 Draw a 2-pixel red 2.40:1 mask:
4718 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
4722 @section drawgraph, adrawgraph
4724 Draw a graph using input video or audio metadata.
4726 It accepts the following parameters:
4730 Set 1st frame metadata key from which metadata values will be used to draw a graph.
4733 Set 1st foreground color expression.
4736 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
4739 Set 2nd foreground color expression.
4742 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
4745 Set 3rd foreground color expression.
4748 Set 4th frame metadata key from which metadata values will be used to draw a graph.
4751 Set 4th foreground color expression.
4754 Set minimal value of metadata value.
4757 Set maximal value of metadata value.
4760 Set graph background color. Default is white.
4765 Available values for mode is:
4772 Default is @code{line}.
4777 Available values for slide is:
4780 Draw new frame when right border is reached.
4783 Replace old columns with new ones.
4786 Scroll from right to left.
4789 Scroll from left to right.
4792 Default is @code{frame}.
4795 Set size of graph video. For the syntax of this option, check the
4796 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
4797 The default value is @code{900x256}.
4799 The foreground color expressions can use the following variables:
4802 Minimal value of metadata value.
4805 Maximal value of metadata value.
4808 Current metadata key value.
4811 The color is defined as 0xAABBGGRR.
4814 Example using metadata from @ref{signalstats} filter:
4816 signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
4819 Example using metadata from @ref{ebur128} filter:
4821 ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
4826 Draw a grid on the input image.
4828 It accepts the following parameters:
4833 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
4837 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
4838 input width and height, respectively, minus @code{thickness}, so image gets
4839 framed. Default to 0.
4842 Specify the color of the grid. For the general syntax of this option,
4843 check the "Color" section in the ffmpeg-utils manual. If the special
4844 value @code{invert} is used, the grid color is the same as the
4845 video with inverted luma.
4848 The expression which sets the thickness of the grid line. Default value is @code{1}.
4850 See below for the list of accepted constants.
4853 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
4854 following constants:
4858 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
4862 horizontal and vertical chroma subsample values. For example for the
4863 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4867 The input grid cell width and height.
4870 The input sample aspect ratio.
4874 The x and y coordinates of some point of grid intersection (meant to configure offset).
4878 The width and height of the drawn cell.
4881 The thickness of the drawn cell.
4883 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
4884 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
4888 @subsection Examples
4892 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
4894 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
4898 Draw a white 3x3 grid with an opacity of 50%:
4900 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
4907 Draw a text string or text from a specified file on top of a video, using the
4908 libfreetype library.
4910 To enable compilation of this filter, you need to configure FFmpeg with
4911 @code{--enable-libfreetype}.
4912 To enable default font fallback and the @var{font} option you need to
4913 configure FFmpeg with @code{--enable-libfontconfig}.
4914 To enable the @var{text_shaping} option, you need to configure FFmpeg with
4915 @code{--enable-libfribidi}.
4919 It accepts the following parameters:
4924 Used to draw a box around text using the background color.
4925 The value must be either 1 (enable) or 0 (disable).
4926 The default value of @var{box} is 0.
4929 Set the width of the border to be drawn around the box using @var{boxcolor}.
4930 The default value of @var{boxborderw} is 0.
4933 The color to be used for drawing box around text. For the syntax of this
4934 option, check the "Color" section in the ffmpeg-utils manual.
4936 The default value of @var{boxcolor} is "white".
4939 Set the width of the border to be drawn around the text using @var{bordercolor}.
4940 The default value of @var{borderw} is 0.
4943 Set the color to be used for drawing border around text. For the syntax of this
4944 option, check the "Color" section in the ffmpeg-utils manual.
4946 The default value of @var{bordercolor} is "black".
4949 Select how the @var{text} is expanded. Can be either @code{none},
4950 @code{strftime} (deprecated) or
4951 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
4955 If true, check and fix text coords to avoid clipping.
4958 The color to be used for drawing fonts. For the syntax of this option, check
4959 the "Color" section in the ffmpeg-utils manual.
4961 The default value of @var{fontcolor} is "black".
4963 @item fontcolor_expr
4964 String which is expanded the same way as @var{text} to obtain dynamic
4965 @var{fontcolor} value. By default this option has empty value and is not
4966 processed. When this option is set, it overrides @var{fontcolor} option.
4969 The font family to be used for drawing text. By default Sans.
4972 The font file to be used for drawing text. The path must be included.
4973 This parameter is mandatory if the fontconfig support is disabled.
4976 This option does not exist, please see the timeline system
4979 Draw the text applying alpha blending. The value can
4980 be either a number between 0.0 and 1.0
4981 The expression accepts the same variables @var{x, y} do.
4982 The default value is 1.
4983 Please see fontcolor_expr
4986 The font size to be used for drawing text.
4987 The default value of @var{fontsize} is 16.
4990 If set to 1, attempt to shape the text (for example, reverse the order of
4991 right-to-left text and join Arabic characters) before drawing it.
4992 Otherwise, just draw the text exactly as given.
4993 By default 1 (if supported).
4996 The flags to be used for loading the fonts.
4998 The flags map the corresponding flags supported by libfreetype, and are
4999 a combination of the following values:
5006 @item vertical_layout
5007 @item force_autohint
5010 @item ignore_global_advance_width
5012 @item ignore_transform
5018 Default value is "default".
5020 For more information consult the documentation for the FT_LOAD_*
5024 The color to be used for drawing a shadow behind the drawn text. For the
5025 syntax of this option, check the "Color" section in the ffmpeg-utils manual.
5027 The default value of @var{shadowcolor} is "black".
5031 The x and y offsets for the text shadow position with respect to the
5032 position of the text. They can be either positive or negative
5033 values. The default value for both is "0".
5036 The starting frame number for the n/frame_num variable. The default value
5040 The size in number of spaces to use for rendering the tab.
5044 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
5045 format. It can be used with or without text parameter. @var{timecode_rate}
5046 option must be specified.
5048 @item timecode_rate, rate, r
5049 Set the timecode frame rate (timecode only).
5052 The text string to be drawn. The text must be a sequence of UTF-8
5054 This parameter is mandatory if no file is specified with the parameter
5058 A text file containing text to be drawn. The text must be a sequence
5059 of UTF-8 encoded characters.
5061 This parameter is mandatory if no text string is specified with the
5062 parameter @var{text}.
5064 If both @var{text} and @var{textfile} are specified, an error is thrown.
5067 If set to 1, the @var{textfile} will be reloaded before each frame.
5068 Be sure to update it atomically, or it may be read partially, or even fail.
5072 The expressions which specify the offsets where text will be drawn
5073 within the video frame. They are relative to the top/left border of the
5076 The default value of @var{x} and @var{y} is "0".
5078 See below for the list of accepted constants and functions.
5081 The parameters for @var{x} and @var{y} are expressions containing the
5082 following constants and functions:
5086 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
5090 horizontal and vertical chroma subsample values. For example for the
5091 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5094 the height of each text line
5102 @item max_glyph_a, ascent
5103 the maximum distance from the baseline to the highest/upper grid
5104 coordinate used to place a glyph outline point, for all the rendered
5106 It is a positive value, due to the grid's orientation with the Y axis
5109 @item max_glyph_d, descent
5110 the maximum distance from the baseline to the lowest grid coordinate
5111 used to place a glyph outline point, for all the rendered glyphs.
5112 This is a negative value, due to the grid's orientation, with the Y axis
5116 maximum glyph height, that is the maximum height for all the glyphs
5117 contained in the rendered text, it is equivalent to @var{ascent} -
5121 maximum glyph width, that is the maximum width for all the glyphs
5122 contained in the rendered text
5125 the number of input frame, starting from 0
5127 @item rand(min, max)
5128 return a random number included between @var{min} and @var{max}
5131 The input sample aspect ratio.
5134 timestamp expressed in seconds, NAN if the input timestamp is unknown
5137 the height of the rendered text
5140 the width of the rendered text
5144 the x and y offset coordinates where the text is drawn.
5146 These parameters allow the @var{x} and @var{y} expressions to refer
5147 each other, so you can for example specify @code{y=x/dar}.
5150 @anchor{drawtext_expansion}
5151 @subsection Text expansion
5153 If @option{expansion} is set to @code{strftime},
5154 the filter recognizes strftime() sequences in the provided text and
5155 expands them accordingly. Check the documentation of strftime(). This
5156 feature is deprecated.
5158 If @option{expansion} is set to @code{none}, the text is printed verbatim.
5160 If @option{expansion} is set to @code{normal} (which is the default),
5161 the following expansion mechanism is used.
5163 The backslash character @samp{\}, followed by any character, always expands to
5164 the second character.
5166 Sequence of the form @code{%@{...@}} are expanded. The text between the
5167 braces is a function name, possibly followed by arguments separated by ':'.
5168 If the arguments contain special characters or delimiters (':' or '@}'),
5169 they should be escaped.
5171 Note that they probably must also be escaped as the value for the
5172 @option{text} option in the filter argument string and as the filter
5173 argument in the filtergraph description, and possibly also for the shell,
5174 that makes up to four levels of escaping; using a text file avoids these
5177 The following functions are available:
5182 The expression evaluation result.
5184 It must take one argument specifying the expression to be evaluated,
5185 which accepts the same constants and functions as the @var{x} and
5186 @var{y} values. Note that not all constants should be used, for
5187 example the text size is not known when evaluating the expression, so
5188 the constants @var{text_w} and @var{text_h} will have an undefined
5191 @item expr_int_format, eif
5192 Evaluate the expression's value and output as formatted integer.
5194 The first argument is the expression to be evaluated, just as for the @var{expr} function.
5195 The second argument specifies the output format. Allowed values are @samp{x},
5196 @samp{X}, @samp{d} and @samp{u}. They are treated exactly as in the
5197 @code{printf} function.
5198 The third parameter is optional and sets the number of positions taken by the output.
5199 It can be used to add padding with zeros from the left.
5202 The time at which the filter is running, expressed in UTC.
5203 It can accept an argument: a strftime() format string.
5206 The time at which the filter is running, expressed in the local time zone.
5207 It can accept an argument: a strftime() format string.
5210 Frame metadata. It must take one argument specifying metadata key.
5213 The frame number, starting from 0.
5216 A 1 character description of the current picture type.
5219 The timestamp of the current frame.
5220 It can take up to two arguments.
5222 The first argument is the format of the timestamp; it defaults to @code{flt}
5223 for seconds as a decimal number with microsecond accuracy; @code{hms} stands
5224 for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy.
5226 The second argument is an offset added to the timestamp.
5230 @subsection Examples
5234 Draw "Test Text" with font FreeSerif, using the default values for the
5235 optional parameters.
5238 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
5242 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
5243 and y=50 (counting from the top-left corner of the screen), text is
5244 yellow with a red box around it. Both the text and the box have an
5248 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
5249 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
5252 Note that the double quotes are not necessary if spaces are not used
5253 within the parameter list.
5256 Show the text at the center of the video frame:
5258 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
5262 Show a text line sliding from right to left in the last row of the video
5263 frame. The file @file{LONG_LINE} is assumed to contain a single line
5266 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
5270 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
5272 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
5276 Draw a single green letter "g", at the center of the input video.
5277 The glyph baseline is placed at half screen height.
5279 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
5283 Show text for 1 second every 3 seconds:
5285 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
5289 Use fontconfig to set the font. Note that the colons need to be escaped.
5291 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
5295 Print the date of a real-time encoding (see strftime(3)):
5297 drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}'
5301 Show text fading in and out (appearing/disappearing):
5304 DS=1.0 # display start
5305 DE=10.0 # display end
5306 FID=1.5 # fade in duration
5307 FOD=5 # fade out duration
5308 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 @}"
5313 For more information about libfreetype, check:
5314 @url{http://www.freetype.org/}.
5316 For more information about fontconfig, check:
5317 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
5319 For more information about libfribidi, check:
5320 @url{http://fribidi.org/}.
5324 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
5326 The filter accepts the following options:
5331 Set low and high threshold values used by the Canny thresholding
5334 The high threshold selects the "strong" edge pixels, which are then
5335 connected through 8-connectivity with the "weak" edge pixels selected
5336 by the low threshold.
5338 @var{low} and @var{high} threshold values must be chosen in the range
5339 [0,1], and @var{low} should be lesser or equal to @var{high}.
5341 Default value for @var{low} is @code{20/255}, and default value for @var{high}
5345 Define the drawing mode.
5349 Draw white/gray wires on black background.
5352 Mix the colors to create a paint/cartoon effect.
5355 Default value is @var{wires}.
5358 @subsection Examples
5362 Standard edge detection with custom values for the hysteresis thresholding:
5364 edgedetect=low=0.1:high=0.4
5368 Painting effect without thresholding:
5370 edgedetect=mode=colormix:high=0
5375 Set brightness, contrast, saturation and approximate gamma adjustment.
5377 The filter accepts the following options:
5381 Set the contrast expression. The value must be a float value in range
5382 @code{-2.0} to @code{2.0}. The default value is "1".
5385 Set the brightness expression. The value must be a float value in
5386 range @code{-1.0} to @code{1.0}. The default value is "0".
5389 Set the saturation expression. The value must be a float in
5390 range @code{0.0} to @code{3.0}. The default value is "1".
5393 Set the gamma expression. The value must be a float in range
5394 @code{0.1} to @code{10.0}. The default value is "1".
5397 Set the gamma expression for red. The value must be a float in
5398 range @code{0.1} to @code{10.0}. The default value is "1".
5401 Set the gamma expression for green. The value must be a float in range
5402 @code{0.1} to @code{10.0}. The default value is "1".
5405 Set the gamma expression for blue. The value must be a float in range
5406 @code{0.1} to @code{10.0}. The default value is "1".
5409 Set the gamma weight expression. It can be used to reduce the effect
5410 of a high gamma value on bright image areas, e.g. keep them from
5411 getting overamplified and just plain white. The value must be a float
5412 in range @code{0.0} to @code{1.0}. A value of @code{0.0} turns the
5413 gamma correction all the way down while @code{1.0} leaves it at its
5414 full strength. Default is "1".
5417 Set when the expressions for brightness, contrast, saturation and
5418 gamma expressions are evaluated.
5420 It accepts the following values:
5423 only evaluate expressions once during the filter initialization or
5424 when a command is processed
5427 evaluate expressions for each incoming frame
5430 Default value is @samp{init}.
5433 The expressions accept the following parameters:
5436 frame count of the input frame starting from 0
5439 byte position of the corresponding packet in the input file, NAN if
5443 frame rate of the input video, NAN if the input frame rate is unknown
5446 timestamp expressed in seconds, NAN if the input timestamp is unknown
5449 @subsection Commands
5450 The filter supports the following commands:
5454 Set the contrast expression.
5457 Set the brightness expression.
5460 Set the saturation expression.
5463 Set the gamma expression.
5466 Set the gamma_r expression.
5469 Set gamma_g expression.
5472 Set gamma_b expression.
5475 Set gamma_weight expression.
5477 The command accepts the same syntax of the corresponding option.
5479 If the specified expression is not valid, it is kept at its current
5486 Apply erosion effect to the video.
5488 This filter replaces the pixel by the local(3x3) minimum.
5490 It accepts the following options:
5497 Allows to limit the maximum change for each plane, default is 65535.
5498 If 0, plane will remain unchanged.
5501 Flag which specifies the pixel to refer to. Default is 255 i.e. all eight
5504 Flags to local 3x3 coordinates maps like this:
5511 @section extractplanes
5513 Extract color channel components from input video stream into
5514 separate grayscale video streams.
5516 The filter accepts the following option:
5520 Set plane(s) to extract.
5522 Available values for planes are:
5533 Choosing planes not available in the input will result in an error.
5534 That means you cannot select @code{r}, @code{g}, @code{b} planes
5535 with @code{y}, @code{u}, @code{v} planes at same time.
5538 @subsection Examples
5542 Extract luma, u and v color channel component from input video frame
5543 into 3 grayscale outputs:
5545 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
5551 Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
5553 For each input image, the filter will compute the optimal mapping from
5554 the input to the output given the codebook length, that is the number
5555 of distinct output colors.
5557 This filter accepts the following options.
5560 @item codebook_length, l
5561 Set codebook length. The value must be a positive integer, and
5562 represents the number of distinct output colors. Default value is 256.
5565 Set the maximum number of iterations to apply for computing the optimal
5566 mapping. The higher the value the better the result and the higher the
5567 computation time. Default value is 1.
5570 Set a random seed, must be an integer included between 0 and
5571 UINT32_MAX. If not specified, or if explicitly set to -1, the filter
5572 will try to use a good random seed on a best effort basis.
5575 Set pal8 output pixel format. This option does not work with codebook
5576 length greater than 256.
5581 Apply a fade-in/out effect to the input video.
5583 It accepts the following parameters:
5587 The effect type can be either "in" for a fade-in, or "out" for a fade-out
5589 Default is @code{in}.
5591 @item start_frame, s
5592 Specify the number of the frame to start applying the fade
5593 effect at. Default is 0.
5596 The number of frames that the fade effect lasts. At the end of the
5597 fade-in effect, the output video will have the same intensity as the input video.
5598 At the end of the fade-out transition, the output video will be filled with the
5599 selected @option{color}.
5603 If set to 1, fade only alpha channel, if one exists on the input.
5606 @item start_time, st
5607 Specify the timestamp (in seconds) of the frame to start to apply the fade
5608 effect. If both start_frame and start_time are specified, the fade will start at
5609 whichever comes last. Default is 0.
5612 The number of seconds for which the fade effect has to last. At the end of the
5613 fade-in effect the output video will have the same intensity as the input video,
5614 at the end of the fade-out transition the output video will be filled with the
5615 selected @option{color}.
5616 If both duration and nb_frames are specified, duration is used. Default is 0
5617 (nb_frames is used by default).
5620 Specify the color of the fade. Default is "black".
5623 @subsection Examples
5627 Fade in the first 30 frames of video:
5632 The command above is equivalent to:
5638 Fade out the last 45 frames of a 200-frame video:
5641 fade=type=out:start_frame=155:nb_frames=45
5645 Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
5647 fade=in:0:25, fade=out:975:25
5651 Make the first 5 frames yellow, then fade in from frame 5-24:
5653 fade=in:5:20:color=yellow
5657 Fade in alpha over first 25 frames of video:
5659 fade=in:0:25:alpha=1
5663 Make the first 5.5 seconds black, then fade in for 0.5 seconds:
5665 fade=t=in:st=5.5:d=0.5
5671 Apply arbitrary expressions to samples in frequency domain
5675 Adjust the dc value (gain) of the luma plane of the image. The filter
5676 accepts an integer value in range @code{0} to @code{1000}. The default
5677 value is set to @code{0}.
5680 Adjust the dc value (gain) of the 1st chroma plane of the image. The
5681 filter accepts an integer value in range @code{0} to @code{1000}. The
5682 default value is set to @code{0}.
5685 Adjust the dc value (gain) of the 2nd chroma plane of the image. The
5686 filter accepts an integer value in range @code{0} to @code{1000}. The
5687 default value is set to @code{0}.
5690 Set the frequency domain weight expression for the luma plane.
5693 Set the frequency domain weight expression for the 1st chroma plane.
5696 Set the frequency domain weight expression for the 2nd chroma plane.
5698 The filter accepts the following variables:
5701 The coordinates of the current sample.
5705 The width and height of the image.
5708 @subsection Examples
5714 fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
5720 fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
5726 fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
5733 Extract a single field from an interlaced image using stride
5734 arithmetic to avoid wasting CPU time. The output frames are marked as
5737 The filter accepts the following options:
5741 Specify whether to extract the top (if the value is @code{0} or
5742 @code{top}) or the bottom field (if the value is @code{1} or
5748 Field matching filter for inverse telecine. It is meant to reconstruct the
5749 progressive frames from a telecined stream. The filter does not drop duplicated
5750 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
5751 followed by a decimation filter such as @ref{decimate} in the filtergraph.
5753 The separation of the field matching and the decimation is notably motivated by
5754 the possibility of inserting a de-interlacing filter fallback between the two.
5755 If the source has mixed telecined and real interlaced content,
5756 @code{fieldmatch} will not be able to match fields for the interlaced parts.
5757 But these remaining combed frames will be marked as interlaced, and thus can be
5758 de-interlaced by a later filter such as @ref{yadif} before decimation.
5760 In addition to the various configuration options, @code{fieldmatch} can take an
5761 optional second stream, activated through the @option{ppsrc} option. If
5762 enabled, the frames reconstruction will be based on the fields and frames from
5763 this second stream. This allows the first input to be pre-processed in order to
5764 help the various algorithms of the filter, while keeping the output lossless
5765 (assuming the fields are matched properly). Typically, a field-aware denoiser,
5766 or brightness/contrast adjustments can help.
5768 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
5769 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
5770 which @code{fieldmatch} is based on. While the semantic and usage are very
5771 close, some behaviour and options names can differ.
5773 The @ref{decimate} filter currently only works for constant frame rate input.
5774 If your input has mixed telecined (30fps) and progressive content with a lower
5775 framerate like 24fps use the following filterchain to produce the necessary cfr
5776 stream: @code{dejudder,fps=30000/1001,fieldmatch,decimate}.
5778 The filter accepts the following options:
5782 Specify the assumed field order of the input stream. Available values are:
5786 Auto detect parity (use FFmpeg's internal parity value).
5788 Assume bottom field first.
5790 Assume top field first.
5793 Note that it is sometimes recommended not to trust the parity announced by the
5796 Default value is @var{auto}.
5799 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
5800 sense that it won't risk creating jerkiness due to duplicate frames when
5801 possible, but if there are bad edits or blended fields it will end up
5802 outputting combed frames when a good match might actually exist. On the other
5803 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
5804 but will almost always find a good frame if there is one. The other values are
5805 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
5806 jerkiness and creating duplicate frames versus finding good matches in sections
5807 with bad edits, orphaned fields, blended fields, etc.
5809 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
5811 Available values are:
5815 2-way matching (p/c)
5817 2-way matching, and trying 3rd match if still combed (p/c + n)
5819 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
5821 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
5822 still combed (p/c + n + u/b)
5824 3-way matching (p/c/n)
5826 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
5827 detected as combed (p/c/n + u/b)
5830 The parenthesis at the end indicate the matches that would be used for that
5831 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
5834 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
5837 Default value is @var{pc_n}.
5840 Mark the main input stream as a pre-processed input, and enable the secondary
5841 input stream as the clean source to pick the fields from. See the filter
5842 introduction for more details. It is similar to the @option{clip2} feature from
5845 Default value is @code{0} (disabled).
5848 Set the field to match from. It is recommended to set this to the same value as
5849 @option{order} unless you experience matching failures with that setting. In
5850 certain circumstances changing the field that is used to match from can have a
5851 large impact on matching performance. Available values are:
5855 Automatic (same value as @option{order}).
5857 Match from the bottom field.
5859 Match from the top field.
5862 Default value is @var{auto}.
5865 Set whether or not chroma is included during the match comparisons. In most
5866 cases it is recommended to leave this enabled. You should set this to @code{0}
5867 only if your clip has bad chroma problems such as heavy rainbowing or other
5868 artifacts. Setting this to @code{0} could also be used to speed things up at
5869 the cost of some accuracy.
5871 Default value is @code{1}.
5875 These define an exclusion band which excludes the lines between @option{y0} and
5876 @option{y1} from being included in the field matching decision. An exclusion
5877 band can be used to ignore subtitles, a logo, or other things that may
5878 interfere with the matching. @option{y0} sets the starting scan line and
5879 @option{y1} sets the ending line; all lines in between @option{y0} and
5880 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
5881 @option{y0} and @option{y1} to the same value will disable the feature.
5882 @option{y0} and @option{y1} defaults to @code{0}.
5885 Set the scene change detection threshold as a percentage of maximum change on
5886 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
5887 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
5888 @option{scthresh} is @code{[0.0, 100.0]}.
5890 Default value is @code{12.0}.
5893 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
5894 account the combed scores of matches when deciding what match to use as the
5895 final match. Available values are:
5899 No final matching based on combed scores.
5901 Combed scores are only used when a scene change is detected.
5903 Use combed scores all the time.
5906 Default is @var{sc}.
5909 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
5910 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
5911 Available values are:
5915 No forced calculation.
5917 Force p/c/n calculations.
5919 Force p/c/n/u/b calculations.
5922 Default value is @var{none}.
5925 This is the area combing threshold used for combed frame detection. This
5926 essentially controls how "strong" or "visible" combing must be to be detected.
5927 Larger values mean combing must be more visible and smaller values mean combing
5928 can be less visible or strong and still be detected. Valid settings are from
5929 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
5930 be detected as combed). This is basically a pixel difference value. A good
5931 range is @code{[8, 12]}.
5933 Default value is @code{9}.
5936 Sets whether or not chroma is considered in the combed frame decision. Only
5937 disable this if your source has chroma problems (rainbowing, etc.) that are
5938 causing problems for the combed frame detection with chroma enabled. Actually,
5939 using @option{chroma}=@var{0} is usually more reliable, except for the case
5940 where there is chroma only combing in the source.
5942 Default value is @code{0}.
5946 Respectively set the x-axis and y-axis size of the window used during combed
5947 frame detection. This has to do with the size of the area in which
5948 @option{combpel} pixels are required to be detected as combed for a frame to be
5949 declared combed. See the @option{combpel} parameter description for more info.
5950 Possible values are any number that is a power of 2 starting at 4 and going up
5953 Default value is @code{16}.
5956 The number of combed pixels inside any of the @option{blocky} by
5957 @option{blockx} size blocks on the frame for the frame to be detected as
5958 combed. While @option{cthresh} controls how "visible" the combing must be, this
5959 setting controls "how much" combing there must be in any localized area (a
5960 window defined by the @option{blockx} and @option{blocky} settings) on the
5961 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
5962 which point no frames will ever be detected as combed). This setting is known
5963 as @option{MI} in TFM/VFM vocabulary.
5965 Default value is @code{80}.
5968 @anchor{p/c/n/u/b meaning}
5969 @subsection p/c/n/u/b meaning
5971 @subsubsection p/c/n
5973 We assume the following telecined stream:
5976 Top fields: 1 2 2 3 4
5977 Bottom fields: 1 2 3 4 4
5980 The numbers correspond to the progressive frame the fields relate to. Here, the
5981 first two frames are progressive, the 3rd and 4th are combed, and so on.
5983 When @code{fieldmatch} is configured to run a matching from bottom
5984 (@option{field}=@var{bottom}) this is how this input stream get transformed:
5989 B 1 2 3 4 4 <-- matching reference
5998 As a result of the field matching, we can see that some frames get duplicated.
5999 To perform a complete inverse telecine, you need to rely on a decimation filter
6000 after this operation. See for instance the @ref{decimate} filter.
6002 The same operation now matching from top fields (@option{field}=@var{top})
6007 T 1 2 2 3 4 <-- matching reference
6017 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
6018 basically, they refer to the frame and field of the opposite parity:
6021 @item @var{p} matches the field of the opposite parity in the previous frame
6022 @item @var{c} matches the field of the opposite parity in the current frame
6023 @item @var{n} matches the field of the opposite parity in the next frame
6028 The @var{u} and @var{b} matching are a bit special in the sense that they match
6029 from the opposite parity flag. In the following examples, we assume that we are
6030 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
6031 'x' is placed above and below each matched fields.
6033 With bottom matching (@option{field}=@var{bottom}):
6038 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6039 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6047 With top matching (@option{field}=@var{top}):
6052 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
6053 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
6061 @subsection Examples
6063 Simple IVTC of a top field first telecined stream:
6065 fieldmatch=order=tff:combmatch=none, decimate
6068 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
6070 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
6075 Transform the field order of the input video.
6077 It accepts the following parameters:
6082 The output field order. Valid values are @var{tff} for top field first or @var{bff}
6083 for bottom field first.
6086 The default value is @samp{tff}.
6088 The transformation is done by shifting the picture content up or down
6089 by one line, and filling the remaining line with appropriate picture content.
6090 This method is consistent with most broadcast field order converters.
6092 If the input video is not flagged as being interlaced, or it is already
6093 flagged as being of the required output field order, then this filter does
6094 not alter the incoming video.
6096 It is very useful when converting to or from PAL DV material,
6097 which is bottom field first.
6101 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
6106 Buffer input images and send them when they are requested.
6108 It is mainly useful when auto-inserted by the libavfilter
6111 It does not take parameters.
6115 Find a rectangular object
6117 It accepts the following options:
6121 Filepath of the object image, needs to be in gray8.
6124 Detection threshold, default is 0.5.
6127 Number of mipmaps, default is 3.
6129 @item xmin, ymin, xmax, ymax
6130 Specifies the rectangle in which to search.
6133 @subsection Examples
6137 Generate a representative palette of a given video using @command{ffmpeg}:
6139 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6145 Cover a rectangular object
6147 It accepts the following options:
6151 Filepath of the optional cover image, needs to be in yuv420.
6156 It accepts the following values:
6159 cover it by the supplied image
6161 cover it by interpolating the surrounding pixels
6164 Default value is @var{blur}.
6167 @subsection Examples
6171 Generate a representative palette of a given video using @command{ffmpeg}:
6173 ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
6180 Convert the input video to one of the specified pixel formats.
6181 Libavfilter will try to pick one that is suitable as input to
6184 It accepts the following parameters:
6188 A '|'-separated list of pixel format names, such as
6189 "pix_fmts=yuv420p|monow|rgb24".
6193 @subsection Examples
6197 Convert the input video to the @var{yuv420p} format
6199 format=pix_fmts=yuv420p
6202 Convert the input video to any of the formats in the list
6204 format=pix_fmts=yuv420p|yuv444p|yuv410p
6211 Convert the video to specified constant frame rate by duplicating or dropping
6212 frames as necessary.
6214 It accepts the following parameters:
6218 The desired output frame rate. The default is @code{25}.
6223 Possible values are:
6226 zero round towards 0
6230 round towards -infinity
6232 round towards +infinity
6236 The default is @code{near}.
6239 Assume the first PTS should be the given value, in seconds. This allows for
6240 padding/trimming at the start of stream. By default, no assumption is made
6241 about the first frame's expected PTS, so no padding or trimming is done.
6242 For example, this could be set to 0 to pad the beginning with duplicates of
6243 the first frame if a video stream starts after the audio stream or to trim any
6244 frames with a negative PTS.
6248 Alternatively, the options can be specified as a flat string:
6249 @var{fps}[:@var{round}].
6251 See also the @ref{setpts} filter.
6253 @subsection Examples
6257 A typical usage in order to set the fps to 25:
6263 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
6265 fps=fps=film:round=near
6271 Pack two different video streams into a stereoscopic video, setting proper
6272 metadata on supported codecs. The two views should have the same size and
6273 framerate and processing will stop when the shorter video ends. Please note
6274 that you may conveniently adjust view properties with the @ref{scale} and
6277 It accepts the following parameters:
6281 The desired packing format. Supported values are:
6286 The views are next to each other (default).
6289 The views are on top of each other.
6292 The views are packed by line.
6295 The views are packed by column.
6298 The views are temporally interleaved.
6307 # Convert left and right views into a frame-sequential video
6308 ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
6310 # Convert views into a side-by-side video with the same output resolution as the input
6311 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
6316 Change the frame rate by interpolating new video output frames from the source
6319 This filter is not designed to function correctly with interlaced media. If
6320 you wish to change the frame rate of interlaced media then you are required
6321 to deinterlace before this filter and re-interlace after this filter.
6323 A description of the accepted options follows.
6327 Specify the output frames per second. This option can also be specified
6328 as a value alone. The default is @code{50}.
6331 Specify the start of a range where the output frame will be created as a
6332 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6333 the default is @code{15}.
6336 Specify the end of a range where the output frame will be created as a
6337 linear interpolation of two frames. The range is [@code{0}-@code{255}],
6338 the default is @code{240}.
6341 Specify the level at which a scene change is detected as a value between
6342 0 and 100 to indicate a new scene; a low value reflects a low
6343 probability for the current frame to introduce a new scene, while a higher
6344 value means the current frame is more likely to be one.
6345 The default is @code{7}.
6348 Specify flags influencing the filter process.
6350 Available value for @var{flags} is:
6353 @item scene_change_detect, scd
6354 Enable scene change detection using the value of the option @var{scene}.
6355 This flag is enabled by default.
6361 Select one frame every N-th frame.
6363 This filter accepts the following option:
6366 Select frame after every @code{step} frames.
6367 Allowed values are positive integers higher than 0. Default value is @code{1}.
6373 Apply a frei0r effect to the input video.
6375 To enable the compilation of this filter, you need to install the frei0r
6376 header and configure FFmpeg with @code{--enable-frei0r}.
6378 It accepts the following parameters:
6383 The name of the frei0r effect to load. If the environment variable
6384 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
6385 directories specified by the colon-separated list in @env{FREIOR_PATH}.
6386 Otherwise, the standard frei0r paths are searched, in this order:
6387 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
6388 @file{/usr/lib/frei0r-1/}.
6391 A '|'-separated list of parameters to pass to the frei0r effect.
6395 A frei0r effect parameter can be a boolean (its value is either
6396 "y" or "n"), a double, a color (specified as
6397 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
6398 numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color"
6399 section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where
6400 @var{X} and @var{Y} are floating point numbers) and/or a string.
6402 The number and types of parameters depend on the loaded effect. If an
6403 effect parameter is not specified, the default value is set.
6405 @subsection Examples
6409 Apply the distort0r effect, setting the first two double parameters:
6411 frei0r=filter_name=distort0r:filter_params=0.5|0.01
6415 Apply the colordistance effect, taking a color as the first parameter:
6417 frei0r=colordistance:0.2/0.3/0.4
6418 frei0r=colordistance:violet
6419 frei0r=colordistance:0x112233
6423 Apply the perspective effect, specifying the top left and top right image
6426 frei0r=perspective:0.2/0.2|0.8/0.2
6430 For more information, see
6431 @url{http://frei0r.dyne.org}
6435 Apply fast and simple postprocessing. It is a faster version of @ref{spp}.
6437 It splits (I)DCT into horizontal/vertical passes. Unlike the simple post-
6438 processing filter, one of them is performed once per block, not per pixel.
6439 This allows for much higher speed.
6441 The filter accepts the following options:
6445 Set quality. This option defines the number of levels for averaging. It accepts
6446 an integer in the range 4-5. Default value is @code{4}.
6449 Force a constant quantization parameter. It accepts an integer in range 0-63.
6450 If not set, the filter will use the QP from the video stream (if available).
6453 Set filter strength. It accepts an integer in range -15 to 32. Lower values mean
6454 more details but also more artifacts, while higher values make the image smoother
6455 but also blurrier. Default value is @code{0} − PSNR optimal.
6458 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
6459 option may cause flicker since the B-Frames have often larger QP. Default is
6460 @code{0} (not enabled).
6466 The filter accepts the following options:
6470 Set the luminance expression.
6472 Set the chrominance blue expression.
6474 Set the chrominance red expression.
6476 Set the alpha expression.
6478 Set the red expression.
6480 Set the green expression.
6482 Set the blue expression.
6485 The colorspace is selected according to the specified options. If one
6486 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
6487 options is specified, the filter will automatically select a YCbCr
6488 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
6489 @option{blue_expr} options is specified, it will select an RGB
6492 If one of the chrominance expression is not defined, it falls back on the other
6493 one. If no alpha expression is specified it will evaluate to opaque value.
6494 If none of chrominance expressions are specified, they will evaluate
6495 to the luminance expression.
6497 The expressions can use the following variables and functions:
6501 The sequential number of the filtered frame, starting from @code{0}.
6505 The coordinates of the current sample.
6509 The width and height of the image.
6513 Width and height scale depending on the currently filtered plane. It is the
6514 ratio between the corresponding luma plane number of pixels and the current
6515 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
6516 @code{0.5,0.5} for chroma planes.
6519 Time of the current frame, expressed in seconds.
6522 Return the value of the pixel at location (@var{x},@var{y}) of the current
6526 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
6530 Return the value of the pixel at location (@var{x},@var{y}) of the
6531 blue-difference chroma plane. Return 0 if there is no such plane.
6534 Return the value of the pixel at location (@var{x},@var{y}) of the
6535 red-difference chroma plane. Return 0 if there is no such plane.
6540 Return the value of the pixel at location (@var{x},@var{y}) of the
6541 red/green/blue component. Return 0 if there is no such component.
6544 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
6545 plane. Return 0 if there is no such plane.
6548 For functions, if @var{x} and @var{y} are outside the area, the value will be
6549 automatically clipped to the closer edge.
6551 @subsection Examples
6555 Flip the image horizontally:
6561 Generate a bidimensional sine wave, with angle @code{PI/3} and a
6562 wavelength of 100 pixels:
6564 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
6568 Generate a fancy enigmatic moving light:
6570 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
6574 Generate a quick emboss effect:
6576 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
6580 Modify RGB components depending on pixel position:
6582 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
6586 Create a radial gradient that is the same size as the input (also see
6587 the @ref{vignette} filter):
6589 geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
6593 Create a linear gradient to use as a mask for another filter, then
6594 compose with @ref{overlay}. In this example the video will gradually
6595 become more blurry from the top to the bottom of the y-axis as defined
6596 by the linear gradient:
6598 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
6604 Fix the banding artifacts that are sometimes introduced into nearly flat
6605 regions by truncation to 8bit color depth.
6606 Interpolate the gradients that should go where the bands are, and
6609 It is designed for playback only. Do not use it prior to
6610 lossy compression, because compression tends to lose the dither and
6611 bring back the bands.
6613 It accepts the following parameters:
6618 The maximum amount by which the filter will change any one pixel. This is also
6619 the threshold for detecting nearly flat regions. Acceptable values range from
6620 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
6624 The neighborhood to fit the gradient to. A larger radius makes for smoother
6625 gradients, but also prevents the filter from modifying the pixels near detailed
6626 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
6627 values will be clipped to the valid range.
6631 Alternatively, the options can be specified as a flat string:
6632 @var{strength}[:@var{radius}]
6634 @subsection Examples
6638 Apply the filter with a @code{3.5} strength and radius of @code{8}:
6644 Specify radius, omitting the strength (which will fall-back to the default
6655 Apply a Hald CLUT to a video stream.
6657 First input is the video stream to process, and second one is the Hald CLUT.
6658 The Hald CLUT input can be a simple picture or a complete video stream.
6660 The filter accepts the following options:
6664 Force termination when the shortest input terminates. Default is @code{0}.
6666 Continue applying the last CLUT after the end of the stream. A value of
6667 @code{0} disable the filter after the last frame of the CLUT is reached.
6668 Default is @code{1}.
6671 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
6672 filters share the same internals).
6674 More information about the Hald CLUT can be found on Eskil Steenberg's website
6675 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
6677 @subsection Workflow examples
6679 @subsubsection Hald CLUT video stream
6681 Generate an identity Hald CLUT stream altered with various effects:
6683 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
6686 Note: make sure you use a lossless codec.
6688 Then use it with @code{haldclut} to apply it on some random stream:
6690 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
6693 The Hald CLUT will be applied to the 10 first seconds (duration of
6694 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
6695 to the remaining frames of the @code{mandelbrot} stream.
6697 @subsubsection Hald CLUT with preview
6699 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
6700 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
6701 biggest possible square starting at the top left of the picture. The remaining
6702 padding pixels (bottom or right) will be ignored. This area can be used to add
6703 a preview of the Hald CLUT.
6705 Typically, the following generated Hald CLUT will be supported by the
6706 @code{haldclut} filter:
6709 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
6710 pad=iw+320 [padded_clut];
6711 smptebars=s=320x256, split [a][b];
6712 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
6713 [main][b] overlay=W-320" -frames:v 1 clut.png
6716 It contains the original and a preview of the effect of the CLUT: SMPTE color
6717 bars are displayed on the right-top, and below the same color bars processed by
6720 Then, the effect of this Hald CLUT can be visualized with:
6722 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
6727 Flip the input video horizontally.
6729 For example, to horizontally flip the input video with @command{ffmpeg}:
6731 ffmpeg -i in.avi -vf "hflip" out.avi
6735 This filter applies a global color histogram equalization on a
6738 It can be used to correct video that has a compressed range of pixel
6739 intensities. The filter redistributes the pixel intensities to
6740 equalize their distribution across the intensity range. It may be
6741 viewed as an "automatically adjusting contrast filter". This filter is
6742 useful only for correcting degraded or poorly captured source
6745 The filter accepts the following options:
6749 Determine the amount of equalization to be applied. As the strength
6750 is reduced, the distribution of pixel intensities more-and-more
6751 approaches that of the input frame. The value must be a float number
6752 in the range [0,1] and defaults to 0.200.
6755 Set the maximum intensity that can generated and scale the output
6756 values appropriately. The strength should be set as desired and then
6757 the intensity can be limited if needed to avoid washing-out. The value
6758 must be a float number in the range [0,1] and defaults to 0.210.
6761 Set the antibanding level. If enabled the filter will randomly vary
6762 the luminance of output pixels by a small amount to avoid banding of
6763 the histogram. Possible values are @code{none}, @code{weak} or
6764 @code{strong}. It defaults to @code{none}.
6769 Compute and draw a color distribution histogram for the input video.
6771 The computed histogram is a representation of the color component
6772 distribution in an image.
6774 The filter accepts the following options:
6780 It accepts the following values:
6783 Standard histogram that displays the color components distribution in an
6784 image. Displays color graph for each color component. Shows distribution of
6785 the Y, U, V, A or R, G, B components, depending on input format, in the
6786 current frame. Below each graph a color component scale meter is shown.
6789 Displays chroma values (U/V color placement) in a two dimensional
6790 graph (which is called a vectorscope). The brighter a pixel in the
6791 vectorscope, the more pixels of the input frame correspond to that pixel
6792 (i.e., more pixels have this chroma value). The V component is displayed on
6793 the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost
6794 side being V = 255. The U component is displayed on the vertical (Y) axis,
6795 with the top representing U = 0 and the bottom representing U = 255.
6797 The position of a white pixel in the graph corresponds to the chroma value of
6798 a pixel of the input clip. The graph can therefore be used to read the hue
6799 (color flavor) and the saturation (the dominance of the hue in the color). As
6800 the hue of a color changes, it moves around the square. At the center of the
6801 square the saturation is zero, which means that the corresponding pixel has no
6802 color. If the amount of a specific color is increased (while leaving the other
6803 colors unchanged) the saturation increases, and the indicator moves towards
6804 the edge of the square.
6807 Chroma values in vectorscope, similar as @code{color} but actual chroma values
6811 Per row/column color component graph. In row mode, the graph on the left side
6812 represents color component value 0 and the right side represents value = 255.
6813 In column mode, the top side represents color component value = 0 and bottom
6814 side represents value = 255.
6816 Default value is @code{levels}.
6819 Set height of level in @code{levels}. Default value is @code{200}.
6820 Allowed range is [50, 2048].
6823 Set height of color scale in @code{levels}. Default value is @code{12}.
6824 Allowed range is [0, 40].
6827 Set step for @code{waveform} mode. Smaller values are useful to find out how
6828 many values of the same luminance are distributed across input rows/columns.
6829 Default value is @code{10}. Allowed range is [1, 255].
6832 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
6833 Default is @code{row}.
6835 @item waveform_mirror
6836 Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1}
6837 means mirrored. In mirrored mode, higher values will be represented on the left
6838 side for @code{row} mode and at the top for @code{column} mode. Default is
6839 @code{0} (unmirrored).
6842 Set display mode for @code{waveform} and @code{levels}.
6843 It accepts the following values:
6846 Display separate graph for the color components side by side in
6847 @code{row} waveform mode or one below the other in @code{column} waveform mode
6848 for @code{waveform} histogram mode. For @code{levels} histogram mode,
6849 per color component graphs are placed below each other.
6851 Using this display mode in @code{waveform} histogram mode makes it easy to
6852 spot color casts in the highlights and shadows of an image, by comparing the
6853 contours of the top and the bottom graphs of each waveform. Since whites,
6854 grays, and blacks are characterized by exactly equal amounts of red, green,
6855 and blue, neutral areas of the picture should display three waveforms of
6856 roughly equal width/height. If not, the correction is easy to perform by
6857 making level adjustments the three waveforms.
6860 Presents information identical to that in the @code{parade}, except
6861 that the graphs representing color components are superimposed directly
6864 This display mode in @code{waveform} histogram mode makes it easier to spot
6865 relative differences or similarities in overlapping areas of the color
6866 components that are supposed to be identical, such as neutral whites, grays,
6869 Default is @code{parade}.
6872 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
6873 Default is @code{linear}.
6876 Set what color components to display for mode @code{levels}.
6877 Default is @code{7}.
6880 @subsection Examples
6885 Calculate and draw histogram:
6887 ffplay -i input -vf histogram
6895 This is a high precision/quality 3d denoise filter. It aims to reduce
6896 image noise, producing smooth images and making still images really
6897 still. It should enhance compressibility.
6899 It accepts the following optional parameters:
6903 A non-negative floating point number which specifies spatial luma strength.
6906 @item chroma_spatial
6907 A non-negative floating point number which specifies spatial chroma strength.
6908 It defaults to 3.0*@var{luma_spatial}/4.0.
6911 A floating point number which specifies luma temporal strength. It defaults to
6912 6.0*@var{luma_spatial}/4.0.
6915 A floating point number which specifies chroma temporal strength. It defaults to
6916 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
6921 Apply a high-quality magnification filter designed for pixel art. This filter
6922 was originally created by Maxim Stepin.
6924 It accepts the following option:
6928 Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
6929 @code{hq3x} and @code{4} for @code{hq4x}.
6930 Default is @code{3}.
6934 Stack input videos horizontally.
6936 All streams must be of same pixel format and of same height.
6938 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
6939 to create same output.
6941 The filter accept the following option:
6945 Set number of input streams. Default is 2.
6950 Modify the hue and/or the saturation of the input.
6952 It accepts the following parameters:
6956 Specify the hue angle as a number of degrees. It accepts an expression,
6957 and defaults to "0".
6960 Specify the saturation in the [-10,10] range. It accepts an expression and
6964 Specify the hue angle as a number of radians. It accepts an
6965 expression, and defaults to "0".
6968 Specify the brightness in the [-10,10] range. It accepts an expression and
6972 @option{h} and @option{H} are mutually exclusive, and can't be
6973 specified at the same time.
6975 The @option{b}, @option{h}, @option{H} and @option{s} option values are
6976 expressions containing the following constants:
6980 frame count of the input frame starting from 0
6983 presentation timestamp of the input frame expressed in time base units
6986 frame rate of the input video, NAN if the input frame rate is unknown
6989 timestamp expressed in seconds, NAN if the input timestamp is unknown
6992 time base of the input video
6995 @subsection Examples
6999 Set the hue to 90 degrees and the saturation to 1.0:
7005 Same command but expressing the hue in radians:
7011 Rotate hue and make the saturation swing between 0
7012 and 2 over a period of 1 second:
7014 hue="H=2*PI*t: s=sin(2*PI*t)+1"
7018 Apply a 3 seconds saturation fade-in effect starting at 0:
7023 The general fade-in expression can be written as:
7025 hue="s=min(0\, max((t-START)/DURATION\, 1))"
7029 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
7031 hue="s=max(0\, min(1\, (8-t)/3))"
7034 The general fade-out expression can be written as:
7036 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
7041 @subsection Commands
7043 This filter supports the following commands:
7049 Modify the hue and/or the saturation and/or brightness of the input video.
7050 The command accepts the same syntax of the corresponding option.
7052 If the specified expression is not valid, it is kept at its current
7058 Detect video interlacing type.
7060 This filter tries to detect if the input frames as interlaced, progressive,
7061 top or bottom field first. It will also try and detect fields that are
7062 repeated between adjacent frames (a sign of telecine).
7064 Single frame detection considers only immediately adjacent frames when classifying each frame.
7065 Multiple frame detection incorporates the classification history of previous frames.
7067 The filter will log these metadata values:
7070 @item single.current_frame
7071 Detected type of current frame using single-frame detection. One of:
7072 ``tff'' (top field first), ``bff'' (bottom field first),
7073 ``progressive'', or ``undetermined''
7076 Cumulative number of frames detected as top field first using single-frame detection.
7079 Cumulative number of frames detected as top field first using multiple-frame detection.
7082 Cumulative number of frames detected as bottom field first using single-frame detection.
7084 @item multiple.current_frame
7085 Detected type of current frame using multiple-frame detection. One of:
7086 ``tff'' (top field first), ``bff'' (bottom field first),
7087 ``progressive'', or ``undetermined''
7090 Cumulative number of frames detected as bottom field first using multiple-frame detection.
7092 @item single.progressive
7093 Cumulative number of frames detected as progressive using single-frame detection.
7095 @item multiple.progressive
7096 Cumulative number of frames detected as progressive using multiple-frame detection.
7098 @item single.undetermined
7099 Cumulative number of frames that could not be classified using single-frame detection.
7101 @item multiple.undetermined
7102 Cumulative number of frames that could not be classified using multiple-frame detection.
7104 @item repeated.current_frame
7105 Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''.
7107 @item repeated.neither
7108 Cumulative number of frames with no repeated field.
7111 Cumulative number of frames with the top field repeated from the previous frame's top field.
7113 @item repeated.bottom
7114 Cumulative number of frames with the bottom field repeated from the previous frame's bottom field.
7117 The filter accepts the following options:
7121 Set interlacing threshold.
7123 Set progressive threshold.
7125 Threshold for repeated field detection.
7127 Number of frames after which a given frame's contribution to the
7128 statistics is halved (i.e., it contributes only 0.5 to it's
7129 classification). The default of 0 means that all frames seen are given
7130 full weight of 1.0 forever.
7131 @item analyze_interlaced_flag
7132 When this is not 0 then idet will use the specified number of frames to determine
7133 if the interlaced flag is accurate, it will not count undetermined frames.
7134 If the flag is found to be accurate it will be used without any further
7135 computations, if it is found to be inaccurate it will be cleared without any
7136 further computations. This allows inserting the idet filter as a low computational
7137 method to clean up the interlaced flag
7142 Deinterleave or interleave fields.
7144 This filter allows one to process interlaced images fields without
7145 deinterlacing them. Deinterleaving splits the input frame into 2
7146 fields (so called half pictures). Odd lines are moved to the top
7147 half of the output image, even lines to the bottom half.
7148 You can process (filter) them independently and then re-interleave them.
7150 The filter accepts the following options:
7154 @item chroma_mode, c
7156 Available values for @var{luma_mode}, @var{chroma_mode} and
7157 @var{alpha_mode} are:
7163 @item deinterleave, d
7164 Deinterleave fields, placing one above the other.
7167 Interleave fields. Reverse the effect of deinterleaving.
7169 Default value is @code{none}.
7172 @item chroma_swap, cs
7173 @item alpha_swap, as
7174 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
7179 Apply inflate effect to the video.
7181 This filter replaces the pixel by the local(3x3) average by taking into account
7182 only values higher than the pixel.
7184 It accepts the following options:
7191 Allows to limit the maximum change for each plane, default is 65535.
7192 If 0, plane will remain unchanged.
7197 Simple interlacing filter from progressive contents. This interleaves upper (or
7198 lower) lines from odd frames with lower (or upper) lines from even frames,
7199 halving the frame rate and preserving image height.
7202 Original Original New Frame
7203 Frame 'j' Frame 'j+1' (tff)
7204 ========== =========== ==================
7205 Line 0 --------------------> Frame 'j' Line 0
7206 Line 1 Line 1 ----> Frame 'j+1' Line 1
7207 Line 2 ---------------------> Frame 'j' Line 2
7208 Line 3 Line 3 ----> Frame 'j+1' Line 3
7210 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
7213 It accepts the following optional parameters:
7217 This determines whether the interlaced frame is taken from the even
7218 (tff - default) or odd (bff) lines of the progressive frame.
7221 Enable (default) or disable the vertical lowpass filter to avoid twitter
7222 interlacing and reduce moire patterns.
7227 Deinterlace input video by applying Donald Graft's adaptive kernel
7228 deinterling. Work on interlaced parts of a video to produce
7231 The description of the accepted parameters follows.
7235 Set the threshold which affects the filter's tolerance when
7236 determining if a pixel line must be processed. It must be an integer
7237 in the range [0,255] and defaults to 10. A value of 0 will result in
7238 applying the process on every pixels.
7241 Paint pixels exceeding the threshold value to white if set to 1.
7245 Set the fields order. Swap fields if set to 1, leave fields alone if
7249 Enable additional sharpening if set to 1. Default is 0.
7252 Enable twoway sharpening if set to 1. Default is 0.
7255 @subsection Examples
7259 Apply default values:
7261 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
7265 Enable additional sharpening:
7271 Paint processed pixels in white:
7277 @section lenscorrection
7279 Correct radial lens distortion
7281 This filter can be used to correct for radial distortion as can result from the use
7282 of wide angle lenses, and thereby re-rectify the image. To find the right parameters
7283 one can use tools available for example as part of opencv or simply trial-and-error.
7284 To use opencv use the calibration sample (under samples/cpp) from the opencv sources
7285 and extract the k1 and k2 coefficients from the resulting matrix.
7287 Note that effectively the same filter is available in the open-source tools Krita and
7288 Digikam from the KDE project.
7290 In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
7291 this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
7292 brightness distribution, so you may want to use both filters together in certain
7293 cases, though you will have to take care of ordering, i.e. whether vignetting should
7294 be applied before or after lens correction.
7298 The filter accepts the following options:
7302 Relative x-coordinate of the focal point of the image, and thereby the center of the
7303 distortion. This value has a range [0,1] and is expressed as fractions of the image
7306 Relative y-coordinate of the focal point of the image, and thereby the center of the
7307 distortion. This value has a range [0,1] and is expressed as fractions of the image
7310 Coefficient of the quadratic correction term. 0.5 means no correction.
7312 Coefficient of the double quadratic correction term. 0.5 means no correction.
7315 The formula that generates the correction is:
7317 @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)
7319 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
7320 distances from the focal point in the source and target images, respectively.
7325 Apply a 3D LUT to an input video.
7327 The filter accepts the following options:
7331 Set the 3D LUT file name.
7333 Currently supported formats:
7345 Select interpolation mode.
7347 Available values are:
7351 Use values from the nearest defined point.
7353 Interpolate values using the 8 points defining a cube.
7355 Interpolate values using a tetrahedron.
7359 @section lut, lutrgb, lutyuv
7361 Compute a look-up table for binding each pixel component input value
7362 to an output value, and apply it to the input video.
7364 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
7365 to an RGB input video.
7367 These filters accept the following parameters:
7370 set first pixel component expression
7372 set second pixel component expression
7374 set third pixel component expression
7376 set fourth pixel component expression, corresponds to the alpha component
7379 set red component expression
7381 set green component expression
7383 set blue component expression
7385 alpha component expression
7388 set Y/luminance component expression
7390 set U/Cb component expression
7392 set V/Cr component expression
7395 Each of them specifies the expression to use for computing the lookup table for
7396 the corresponding pixel component values.
7398 The exact component associated to each of the @var{c*} options depends on the
7401 The @var{lut} filter requires either YUV or RGB pixel formats in input,
7402 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
7404 The expressions can contain the following constants and functions:
7409 The input width and height.
7412 The input value for the pixel component.
7415 The input value, clipped to the @var{minval}-@var{maxval} range.
7418 The maximum value for the pixel component.
7421 The minimum value for the pixel component.
7424 The negated value for the pixel component value, clipped to the
7425 @var{minval}-@var{maxval} range; it corresponds to the expression
7426 "maxval-clipval+minval".
7429 The computed value in @var{val}, clipped to the
7430 @var{minval}-@var{maxval} range.
7432 @item gammaval(gamma)
7433 The computed gamma correction value of the pixel component value,
7434 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
7436 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
7440 All expressions default to "val".
7442 @subsection Examples
7448 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
7449 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
7452 The above is the same as:
7454 lutrgb="r=negval:g=negval:b=negval"
7455 lutyuv="y=negval:u=negval:v=negval"
7465 Remove chroma components, turning the video into a graytone image:
7467 lutyuv="u=128:v=128"
7471 Apply a luma burning effect:
7477 Remove green and blue components:
7483 Set a constant alpha channel value on input:
7485 format=rgba,lutrgb=a="maxval-minval/2"
7489 Correct luminance gamma by a factor of 0.5:
7491 lutyuv=y=gammaval(0.5)
7495 Discard least significant bits of luma:
7497 lutyuv=y='bitand(val, 128+64+32)'
7501 @section mergeplanes
7503 Merge color channel components from several video streams.
7505 The filter accepts up to 4 input streams, and merge selected input
7506 planes to the output video.
7508 This filter accepts the following options:
7511 Set input to output plane mapping. Default is @code{0}.
7513 The mappings is specified as a bitmap. It should be specified as a
7514 hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
7515 mapping for the first plane of the output stream. 'A' sets the number of
7516 the input stream to use (from 0 to 3), and 'a' the plane number of the
7517 corresponding input to use (from 0 to 3). The rest of the mappings is
7518 similar, 'Bb' describes the mapping for the output stream second
7519 plane, 'Cc' describes the mapping for the output stream third plane and
7520 'Dd' describes the mapping for the output stream fourth plane.
7523 Set output pixel format. Default is @code{yuva444p}.
7526 @subsection Examples
7530 Merge three gray video streams of same width and height into single video stream:
7532 [a0][a1][a2]mergeplanes=0x001020:yuv444p
7536 Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
7538 [a0][a1]mergeplanes=0x00010210:yuva444p
7542 Swap Y and A plane in yuva444p stream:
7544 format=yuva444p,mergeplanes=0x03010200:yuva444p
7548 Swap U and V plane in yuv420p stream:
7550 format=yuv420p,mergeplanes=0x000201:yuv420p
7554 Cast a rgb24 clip to yuv444p:
7556 format=rgb24,mergeplanes=0x000102:yuv444p
7562 Apply motion-compensation deinterlacing.
7564 It needs one field per frame as input and must thus be used together
7565 with yadif=1/3 or equivalent.
7567 This filter accepts the following options:
7570 Set the deinterlacing mode.
7572 It accepts one of the following values:
7577 use iterative motion estimation
7579 like @samp{slow}, but use multiple reference frames.
7581 Default value is @samp{fast}.
7584 Set the picture field parity assumed for the input video. It must be
7585 one of the following values:
7589 assume top field first
7591 assume bottom field first
7594 Default value is @samp{bff}.
7597 Set per-block quantization parameter (QP) used by the internal
7600 Higher values should result in a smoother motion vector field but less
7601 optimal individual vectors. Default value is 1.
7606 Drop frames that do not differ greatly from the previous frame in
7607 order to reduce frame rate.
7609 The main use of this filter is for very-low-bitrate encoding
7610 (e.g. streaming over dialup modem), but it could in theory be used for
7611 fixing movies that were inverse-telecined incorrectly.
7613 A description of the accepted options follows.
7617 Set the maximum number of consecutive frames which can be dropped (if
7618 positive), or the minimum interval between dropped frames (if
7619 negative). If the value is 0, the frame is dropped unregarding the
7620 number of previous sequentially dropped frames.
7627 Set the dropping threshold values.
7629 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
7630 represent actual pixel value differences, so a threshold of 64
7631 corresponds to 1 unit of difference for each pixel, or the same spread
7632 out differently over the block.
7634 A frame is a candidate for dropping if no 8x8 blocks differ by more
7635 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
7636 meaning the whole image) differ by more than a threshold of @option{lo}.
7638 Default value for @option{hi} is 64*12, default value for @option{lo} is
7639 64*5, and default value for @option{frac} is 0.33.
7647 It accepts an integer in input; if non-zero it negates the
7648 alpha component (if available). The default value in input is 0.
7652 Force libavfilter not to use any of the specified pixel formats for the
7653 input to the next filter.
7655 It accepts the following parameters:
7659 A '|'-separated list of pixel format names, such as
7660 apix_fmts=yuv420p|monow|rgb24".
7664 @subsection Examples
7668 Force libavfilter to use a format different from @var{yuv420p} for the
7669 input to the vflip filter:
7671 noformat=pix_fmts=yuv420p,vflip
7675 Convert the input video to any of the formats not contained in the list:
7677 noformat=yuv420p|yuv444p|yuv410p
7683 Add noise on video input frame.
7685 The filter accepts the following options:
7693 Set noise seed for specific pixel component or all pixel components in case
7694 of @var{all_seed}. Default value is @code{123457}.
7696 @item all_strength, alls
7697 @item c0_strength, c0s
7698 @item c1_strength, c1s
7699 @item c2_strength, c2s
7700 @item c3_strength, c3s
7701 Set noise strength for specific pixel component or all pixel components in case
7702 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
7704 @item all_flags, allf
7709 Set pixel component flags or set flags for all components if @var{all_flags}.
7710 Available values for component flags are:
7713 averaged temporal noise (smoother)
7715 mix random noise with a (semi)regular pattern
7717 temporal noise (noise pattern changes between frames)
7719 uniform noise (gaussian otherwise)
7723 @subsection Examples
7725 Add temporal and uniform noise to input video:
7727 noise=alls=20:allf=t+u
7732 Pass the video source unchanged to the output.
7735 Optical Character Recognition
7737 This filter uses Tesseract for optical character recognition.
7739 It accepts the following options:
7743 Set datapath to tesseract data. Default is to use whatever was
7744 set at installation.
7747 Set language, default is "eng".
7750 Set character whitelist.
7753 Set character blacklist.
7756 The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
7760 Apply a video transform using libopencv.
7762 To enable this filter, install the libopencv library and headers and
7763 configure FFmpeg with @code{--enable-libopencv}.
7765 It accepts the following parameters:
7770 The name of the libopencv filter to apply.
7773 The parameters to pass to the libopencv filter. If not specified, the default
7778 Refer to the official libopencv documentation for more precise
7780 @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html}
7782 Several libopencv filters are supported; see the following subsections.
7787 Dilate an image by using a specific structuring element.
7788 It corresponds to the libopencv function @code{cvDilate}.
7790 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
7792 @var{struct_el} represents a structuring element, and has the syntax:
7793 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
7795 @var{cols} and @var{rows} represent the number of columns and rows of
7796 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
7797 point, and @var{shape} the shape for the structuring element. @var{shape}
7798 must be "rect", "cross", "ellipse", or "custom".
7800 If the value for @var{shape} is "custom", it must be followed by a
7801 string of the form "=@var{filename}". The file with name
7802 @var{filename} is assumed to represent a binary image, with each
7803 printable character corresponding to a bright pixel. When a custom
7804 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
7805 or columns and rows of the read file are assumed instead.
7807 The default value for @var{struct_el} is "3x3+0x0/rect".
7809 @var{nb_iterations} specifies the number of times the transform is
7810 applied to the image, and defaults to 1.
7814 # Use the default values
7817 # Dilate using a structuring element with a 5x5 cross, iterating two times
7818 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
7820 # Read the shape from the file diamond.shape, iterating two times.
7821 # The file diamond.shape may contain a pattern of characters like this
7827 # The specified columns and rows are ignored
7828 # but the anchor point coordinates are not
7829 ocv=dilate:0x0+2x2/custom=diamond.shape|2
7834 Erode an image by using a specific structuring element.
7835 It corresponds to the libopencv function @code{cvErode}.
7837 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
7838 with the same syntax and semantics as the @ref{dilate} filter.
7842 Smooth the input video.
7844 The filter takes the following parameters:
7845 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
7847 @var{type} is the type of smooth filter to apply, and must be one of
7848 the following values: "blur", "blur_no_scale", "median", "gaussian",
7849 or "bilateral". The default value is "gaussian".
7851 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
7852 depend on the smooth type. @var{param1} and
7853 @var{param2} accept integer positive values or 0. @var{param3} and
7854 @var{param4} accept floating point values.
7856 The default value for @var{param1} is 3. The default value for the
7857 other parameters is 0.
7859 These parameters correspond to the parameters assigned to the
7860 libopencv function @code{cvSmooth}.
7865 Overlay one video on top of another.
7867 It takes two inputs and has one output. The first input is the "main"
7868 video on which the second input is overlaid.
7870 It accepts the following parameters:
7872 A description of the accepted options follows.
7877 Set the expression for the x and y coordinates of the overlaid video
7878 on the main video. Default value is "0" for both expressions. In case
7879 the expression is invalid, it is set to a huge value (meaning that the
7880 overlay will not be displayed within the output visible area).
7883 The action to take when EOF is encountered on the secondary input; it accepts
7884 one of the following values:
7888 Repeat the last frame (the default).
7892 Pass the main input through.
7896 Set when the expressions for @option{x}, and @option{y} are evaluated.
7898 It accepts the following values:
7901 only evaluate expressions once during the filter initialization or
7902 when a command is processed
7905 evaluate expressions for each incoming frame
7908 Default value is @samp{frame}.
7911 If set to 1, force the output to terminate when the shortest input
7912 terminates. Default value is 0.
7915 Set the format for the output video.
7917 It accepts the following values:
7932 Default value is @samp{yuv420}.
7934 @item rgb @emph{(deprecated)}
7935 If set to 1, force the filter to accept inputs in the RGB
7936 color space. Default value is 0. This option is deprecated, use
7937 @option{format} instead.
7940 If set to 1, force the filter to draw the last overlay frame over the
7941 main input until the end of the stream. A value of 0 disables this
7942 behavior. Default value is 1.
7945 The @option{x}, and @option{y} expressions can contain the following
7951 The main input width and height.
7955 The overlay input width and height.
7959 The computed values for @var{x} and @var{y}. They are evaluated for
7964 horizontal and vertical chroma subsample values of the output
7965 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
7969 the number of input frame, starting from 0
7972 the position in the file of the input frame, NAN if unknown
7975 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
7979 Note that the @var{n}, @var{pos}, @var{t} variables are available only
7980 when evaluation is done @emph{per frame}, and will evaluate to NAN
7981 when @option{eval} is set to @samp{init}.
7983 Be aware that frames are taken from each input video in timestamp
7984 order, hence, if their initial timestamps differ, it is a good idea
7985 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
7986 have them begin in the same zero timestamp, as the example for
7987 the @var{movie} filter does.
7989 You can chain together more overlays but you should test the
7990 efficiency of such approach.
7992 @subsection Commands
7994 This filter supports the following commands:
7998 Modify the x and y of the overlay input.
7999 The command accepts the same syntax of the corresponding option.
8001 If the specified expression is not valid, it is kept at its current
8005 @subsection Examples
8009 Draw the overlay at 10 pixels from the bottom right corner of the main
8012 overlay=main_w-overlay_w-10:main_h-overlay_h-10
8015 Using named options the example above becomes:
8017 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
8021 Insert a transparent PNG logo in the bottom left corner of the input,
8022 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
8024 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
8028 Insert 2 different transparent PNG logos (second logo on bottom
8029 right corner) using the @command{ffmpeg} tool:
8031 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
8035 Add a transparent color layer on top of the main video; @code{WxH}
8036 must specify the size of the main input to the overlay filter:
8038 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
8042 Play an original video and a filtered version (here with the deshake
8043 filter) side by side using the @command{ffplay} tool:
8045 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
8048 The above command is the same as:
8050 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
8054 Make a sliding overlay appearing from the left to the right top part of the
8055 screen starting since time 2:
8057 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
8061 Compose output by putting two input videos side to side:
8063 ffmpeg -i left.avi -i right.avi -filter_complex "
8064 nullsrc=size=200x100 [background];
8065 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
8066 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
8067 [background][left] overlay=shortest=1 [background+left];
8068 [background+left][right] overlay=shortest=1:x=100 [left+right]
8073 Mask 10-20 seconds of a video by applying the delogo filter to a section
8075 ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
8076 -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]'
8081 Chain several overlays in cascade:
8083 nullsrc=s=200x200 [bg];
8084 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
8085 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
8086 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
8087 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
8088 [in3] null, [mid2] overlay=100:100 [out0]
8095 Apply Overcomplete Wavelet denoiser.
8097 The filter accepts the following options:
8103 Larger depth values will denoise lower frequency components more, but
8104 slow down filtering.
8106 Must be an int in the range 8-16, default is @code{8}.
8108 @item luma_strength, ls
8111 Must be a double value in the range 0-1000, default is @code{1.0}.
8113 @item chroma_strength, cs
8114 Set chroma strength.
8116 Must be a double value in the range 0-1000, default is @code{1.0}.
8122 Add paddings to the input image, and place the original input at the
8123 provided @var{x}, @var{y} coordinates.
8125 It accepts the following parameters:
8130 Specify an expression for the size of the output image with the
8131 paddings added. If the value for @var{width} or @var{height} is 0, the
8132 corresponding input size is used for the output.
8134 The @var{width} expression can reference the value set by the
8135 @var{height} expression, and vice versa.
8137 The default value of @var{width} and @var{height} is 0.
8141 Specify the offsets to place the input image at within the padded area,
8142 with respect to the top/left border of the output image.
8144 The @var{x} expression can reference the value set by the @var{y}
8145 expression, and vice versa.
8147 The default value of @var{x} and @var{y} is 0.
8150 Specify the color of the padded area. For the syntax of this option,
8151 check the "Color" section in the ffmpeg-utils manual.
8153 The default value of @var{color} is "black".
8156 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
8157 options are expressions containing the following constants:
8162 The input video width and height.
8166 These are the same as @var{in_w} and @var{in_h}.
8170 The output width and height (the size of the padded area), as
8171 specified by the @var{width} and @var{height} expressions.
8175 These are the same as @var{out_w} and @var{out_h}.
8179 The x and y offsets as specified by the @var{x} and @var{y}
8180 expressions, or NAN if not yet specified.
8183 same as @var{iw} / @var{ih}
8186 input sample aspect ratio
8189 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
8193 The horizontal and vertical chroma subsample values. For example for the
8194 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
8197 @subsection Examples
8201 Add paddings with the color "violet" to the input video. The output video
8202 size is 640x480, and the top-left corner of the input video is placed at
8205 pad=640:480:0:40:violet
8208 The example above is equivalent to the following command:
8210 pad=width=640:height=480:x=0:y=40:color=violet
8214 Pad the input to get an output with dimensions increased by 3/2,
8215 and put the input video at the center of the padded area:
8217 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
8221 Pad the input to get a squared output with size equal to the maximum
8222 value between the input width and height, and put the input video at
8223 the center of the padded area:
8225 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
8229 Pad the input to get a final w/h ratio of 16:9:
8231 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
8235 In case of anamorphic video, in order to set the output display aspect
8236 correctly, it is necessary to use @var{sar} in the expression,
8237 according to the relation:
8239 (ih * X / ih) * sar = output_dar
8240 X = output_dar / sar
8243 Thus the previous example needs to be modified to:
8245 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
8249 Double the output size and put the input video in the bottom-right
8250 corner of the output padded area:
8252 pad="2*iw:2*ih:ow-iw:oh-ih"
8259 Generate one palette for a whole video stream.
8261 It accepts the following options:
8265 Set the maximum number of colors to quantize in the palette.
8266 Note: the palette will still contain 256 colors; the unused palette entries
8269 @item reserve_transparent
8270 Create a palette of 255 colors maximum and reserve the last one for
8271 transparency. Reserving the transparency color is useful for GIF optimization.
8272 If not set, the maximum of colors in the palette will be 256. You probably want
8273 to disable this option for a standalone image.
8277 Set statistics mode.
8279 It accepts the following values:
8282 Compute full frame histograms.
8284 Compute histograms only for the part that differs from previous frame. This
8285 might be relevant to give more importance to the moving part of your input if
8286 the background is static.
8289 Default value is @var{full}.
8292 The filter also exports the frame metadata @code{lavfi.color_quant_ratio}
8293 (@code{nb_color_in / nb_color_out}) which you can use to evaluate the degree of
8294 color quantization of the palette. This information is also visible at
8295 @var{info} logging level.
8297 @subsection Examples
8301 Generate a representative palette of a given video using @command{ffmpeg}:
8303 ffmpeg -i input.mkv -vf palettegen palette.png
8309 Use a palette to downsample an input video stream.
8311 The filter takes two inputs: one video stream and a palette. The palette must
8312 be a 256 pixels image.
8314 It accepts the following options:
8318 Select dithering mode. Available algorithms are:
8321 Ordered 8x8 bayer dithering (deterministic)
8323 Dithering as defined by Paul Heckbert in 1982 (simple error diffusion).
8324 Note: this dithering is sometimes considered "wrong" and is included as a
8326 @item floyd_steinberg
8327 Floyd and Steingberg dithering (error diffusion)
8329 Frankie Sierra dithering v2 (error diffusion)
8331 Frankie Sierra dithering v2 "Lite" (error diffusion)
8334 Default is @var{sierra2_4a}.
8337 When @var{bayer} dithering is selected, this option defines the scale of the
8338 pattern (how much the crosshatch pattern is visible). A low value means more
8339 visible pattern for less banding, and higher value means less visible pattern
8340 at the cost of more banding.
8342 The option must be an integer value in the range [0,5]. Default is @var{2}.
8345 If set, define the zone to process
8349 Only the changing rectangle will be reprocessed. This is similar to GIF
8350 cropping/offsetting compression mechanism. This option can be useful for speed
8351 if only a part of the image is changing, and has use cases such as limiting the
8352 scope of the error diffusal @option{dither} to the rectangle that bounds the
8353 moving scene (it leads to more deterministic output if the scene doesn't change
8354 much, and as a result less moving noise and better GIF compression).
8357 Default is @var{none}.
8360 @subsection Examples
8364 Use a palette (generated for example with @ref{palettegen}) to encode a GIF
8365 using @command{ffmpeg}:
8367 ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
8371 @section perspective
8373 Correct perspective of video not recorded perpendicular to the screen.
8375 A description of the accepted parameters follows.
8386 Set coordinates expression for top left, top right, bottom left and bottom right corners.
8387 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
8388 If the @code{sense} option is set to @code{source}, then the specified points will be sent
8389 to the corners of the destination. If the @code{sense} option is set to @code{destination},
8390 then the corners of the source will be sent to the specified coordinates.
8392 The expressions can use the following variables:
8397 the width and height of video frame.
8401 Set interpolation for perspective correction.
8403 It accepts the following values:
8409 Default value is @samp{linear}.
8412 Set interpretation of coordinate options.
8414 It accepts the following values:
8418 Send point in the source specified by the given coordinates to
8419 the corners of the destination.
8421 @item 1, destination
8423 Send the corners of the source to the point in the destination specified
8424 by the given coordinates.
8426 Default value is @samp{source}.
8432 Delay interlaced video by one field time so that the field order changes.
8434 The intended use is to fix PAL movies that have been captured with the
8435 opposite field order to the film-to-video transfer.
8437 A description of the accepted parameters follows.
8443 It accepts the following values:
8446 Capture field order top-first, transfer bottom-first.
8447 Filter will delay the bottom field.
8450 Capture field order bottom-first, transfer top-first.
8451 Filter will delay the top field.
8454 Capture and transfer with the same field order. This mode only exists
8455 for the documentation of the other options to refer to, but if you
8456 actually select it, the filter will faithfully do nothing.
8459 Capture field order determined automatically by field flags, transfer
8461 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
8462 basis using field flags. If no field information is available,
8463 then this works just like @samp{u}.
8466 Capture unknown or varying, transfer opposite.
8467 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
8468 analyzing the images and selecting the alternative that produces best
8469 match between the fields.
8472 Capture top-first, transfer unknown or varying.
8473 Filter selects among @samp{t} and @samp{p} using image analysis.
8476 Capture bottom-first, transfer unknown or varying.
8477 Filter selects among @samp{b} and @samp{p} using image analysis.
8480 Capture determined by field flags, transfer unknown or varying.
8481 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
8482 image analysis. If no field information is available, then this works just
8483 like @samp{U}. This is the default mode.
8486 Both capture and transfer unknown or varying.
8487 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
8491 @section pixdesctest
8493 Pixel format descriptor test filter, mainly useful for internal
8494 testing. The output video should be equal to the input video.
8498 format=monow, pixdesctest
8501 can be used to test the monowhite pixel format descriptor definition.
8505 Enable the specified chain of postprocessing subfilters using libpostproc. This
8506 library should be automatically selected with a GPL build (@code{--enable-gpl}).
8507 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
8508 Each subfilter and some options have a short and a long name that can be used
8509 interchangeably, i.e. dr/dering are the same.
8511 The filters accept the following options:
8515 Set postprocessing subfilters string.
8518 All subfilters share common options to determine their scope:
8522 Honor the quality commands for this subfilter.
8525 Do chrominance filtering, too (default).
8528 Do luminance filtering only (no chrominance).
8531 Do chrominance filtering only (no luminance).
8534 These options can be appended after the subfilter name, separated by a '|'.
8536 Available subfilters are:
8539 @item hb/hdeblock[|difference[|flatness]]
8540 Horizontal deblocking filter
8543 Difference factor where higher values mean more deblocking (default: @code{32}).
8545 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8548 @item vb/vdeblock[|difference[|flatness]]
8549 Vertical deblocking filter
8552 Difference factor where higher values mean more deblocking (default: @code{32}).
8554 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8557 @item ha/hadeblock[|difference[|flatness]]
8558 Accurate horizontal deblocking filter
8561 Difference factor where higher values mean more deblocking (default: @code{32}).
8563 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8566 @item va/vadeblock[|difference[|flatness]]
8567 Accurate vertical deblocking filter
8570 Difference factor where higher values mean more deblocking (default: @code{32}).
8572 Flatness threshold where lower values mean more deblocking (default: @code{39}).
8576 The horizontal and vertical deblocking filters share the difference and
8577 flatness values so you cannot set different horizontal and vertical
8582 Experimental horizontal deblocking filter
8585 Experimental vertical deblocking filter
8590 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
8593 larger -> stronger filtering
8595 larger -> stronger filtering
8597 larger -> stronger filtering
8600 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
8603 Stretch luminance to @code{0-255}.
8606 @item lb/linblenddeint
8607 Linear blend deinterlacing filter that deinterlaces the given block by
8608 filtering all lines with a @code{(1 2 1)} filter.
8610 @item li/linipoldeint
8611 Linear interpolating deinterlacing filter that deinterlaces the given block by
8612 linearly interpolating every second line.
8614 @item ci/cubicipoldeint
8615 Cubic interpolating deinterlacing filter deinterlaces the given block by
8616 cubically interpolating every second line.
8618 @item md/mediandeint
8619 Median deinterlacing filter that deinterlaces the given block by applying a
8620 median filter to every second line.
8622 @item fd/ffmpegdeint
8623 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
8624 second line with a @code{(-1 4 2 4 -1)} filter.
8627 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
8628 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
8630 @item fq/forceQuant[|quantizer]
8631 Overrides the quantizer table from the input with the constant quantizer you
8639 Default pp filter combination (@code{hb|a,vb|a,dr|a})
8642 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
8645 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
8648 @subsection Examples
8652 Apply horizontal and vertical deblocking, deringing and automatic
8653 brightness/contrast:
8659 Apply default filters without brightness/contrast correction:
8665 Apply default filters and temporal denoiser:
8667 pp=default/tmpnoise|1|2|3
8671 Apply deblocking on luminance only, and switch vertical deblocking on or off
8672 automatically depending on available CPU time:
8679 Apply Postprocessing filter 7. It is variant of the @ref{spp} filter,
8680 similar to spp = 6 with 7 point DCT, where only the center sample is
8683 The filter accepts the following options:
8687 Force a constant quantization parameter. It accepts an integer in range
8688 0 to 63. If not set, the filter will use the QP from the video stream
8692 Set thresholding mode. Available modes are:
8696 Set hard thresholding.
8698 Set soft thresholding (better de-ringing effect, but likely blurrier).
8700 Set medium thresholding (good results, default).
8706 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
8707 Ratio) between two input videos.
8709 This filter takes in input two input videos, the first input is
8710 considered the "main" source and is passed unchanged to the
8711 output. The second input is used as a "reference" video for computing
8714 Both video inputs must have the same resolution and pixel format for
8715 this filter to work correctly. Also it assumes that both inputs
8716 have the same number of frames, which are compared one by one.
8718 The obtained average PSNR is printed through the logging system.
8720 The filter stores the accumulated MSE (mean squared error) of each
8721 frame, and at the end of the processing it is averaged across all frames
8722 equally, and the following formula is applied to obtain the PSNR:
8725 PSNR = 10*log10(MAX^2/MSE)
8728 Where MAX is the average of the maximum values of each component of the
8731 The description of the accepted parameters follows.
8735 If specified the filter will use the named file to save the PSNR of
8736 each individual frame.
8739 The file printed if @var{stats_file} is selected, contains a sequence of
8740 key/value pairs of the form @var{key}:@var{value} for each compared
8743 A description of each shown parameter follows:
8747 sequential number of the input frame, starting from 1
8750 Mean Square Error pixel-by-pixel average difference of the compared
8751 frames, averaged over all the image components.
8753 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
8754 Mean Square Error pixel-by-pixel average difference of the compared
8755 frames for the component specified by the suffix.
8757 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
8758 Peak Signal to Noise ratio of the compared frames for the component
8759 specified by the suffix.
8764 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
8765 [main][ref] psnr="stats_file=stats.log" [out]
8768 On this example the input file being processed is compared with the
8769 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
8770 is stored in @file{stats.log}.
8775 Pulldown reversal (inverse telecine) filter, capable of handling mixed
8776 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
8779 The pullup filter is designed to take advantage of future context in making
8780 its decisions. This filter is stateless in the sense that it does not lock
8781 onto a pattern to follow, but it instead looks forward to the following
8782 fields in order to identify matches and rebuild progressive frames.
8784 To produce content with an even framerate, insert the fps filter after
8785 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
8786 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
8788 The filter accepts the following options:
8795 These options set the amount of "junk" to ignore at the left, right, top, and
8796 bottom of the image, respectively. Left and right are in units of 8 pixels,
8797 while top and bottom are in units of 2 lines.
8798 The default is 8 pixels on each side.
8801 Set the strict breaks. Setting this option to 1 will reduce the chances of
8802 filter generating an occasional mismatched frame, but it may also cause an
8803 excessive number of frames to be dropped during high motion sequences.
8804 Conversely, setting it to -1 will make filter match fields more easily.
8805 This may help processing of video where there is slight blurring between
8806 the fields, but may also cause there to be interlaced frames in the output.
8807 Default value is @code{0}.
8810 Set the metric plane to use. It accepts the following values:
8816 Use chroma blue plane.
8819 Use chroma red plane.
8822 This option may be set to use chroma plane instead of the default luma plane
8823 for doing filter's computations. This may improve accuracy on very clean
8824 source material, but more likely will decrease accuracy, especially if there
8825 is chroma noise (rainbow effect) or any grayscale video.
8826 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
8827 load and make pullup usable in realtime on slow machines.
8830 For best results (without duplicated frames in the output file) it is
8831 necessary to change the output frame rate. For example, to inverse
8832 telecine NTSC input:
8834 ffmpeg -i input -vf pullup -r 24000/1001 ...
8839 Change video quantization parameters (QP).
8841 The filter accepts the following option:
8845 Set expression for quantization parameter.
8848 The expression is evaluated through the eval API and can contain, among others,
8849 the following constants:
8853 1 if index is not 129, 0 otherwise.
8856 Sequentional index starting from -129 to 128.
8859 @subsection Examples
8871 Flush video frames from internal cache of frames into a random order.
8872 No frame is discarded.
8873 Inspired by @ref{frei0r} nervous filter.
8877 Set size in number of frames of internal cache, in range from @code{2} to
8878 @code{512}. Default is @code{30}.
8881 Set seed for random number generator, must be an integer included between
8882 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
8883 less than @code{0}, the filter will try to use a good random seed on a
8887 @section removegrain
8889 The removegrain filter is a spatial denoiser for progressive video.
8893 Set mode for the first plane.
8896 Set mode for the second plane.
8899 Set mode for the third plane.
8902 Set mode for the fourth plane.
8905 Range of mode is from 0 to 24. Description of each mode follows:
8909 Leave input plane unchanged. Default.
8912 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
8915 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
8918 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
8921 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels.
8922 This is equivalent to a median filter.
8925 Line-sensitive clipping giving the minimal change.
8928 Line-sensitive clipping, intermediate.
8931 Line-sensitive clipping, intermediate.
8934 Line-sensitive clipping, intermediate.
8937 Line-sensitive clipping on a line where the neighbours pixels are the closest.
8940 Replaces the target pixel with the closest neighbour.
8943 [1 2 1] horizontal and vertical kernel blur.
8949 Bob mode, interpolates top field from the line where the neighbours
8950 pixels are the closest.
8953 Bob mode, interpolates bottom field from the line where the neighbours
8954 pixels are the closest.
8957 Bob mode, interpolates top field. Same as 13 but with a more complicated
8958 interpolation formula.
8961 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
8962 interpolation formula.
8965 Clips the pixel with the minimum and maximum of respectively the maximum and
8966 minimum of each pair of opposite neighbour pixels.
8969 Line-sensitive clipping using opposite neighbours whose greatest distance from
8970 the current pixel is minimal.
8973 Replaces the pixel with the average of its 8 neighbours.
8976 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
8979 Clips pixels using the averages of opposite neighbour.
8982 Same as mode 21 but simpler and faster.
8985 Small edge and halo removal, but reputed useless.
8993 Suppress a TV station logo, using an image file to determine which
8994 pixels comprise the logo. It works by filling in the pixels that
8995 comprise the logo with neighboring pixels.
8997 The filter accepts the following options:
9001 Set the filter bitmap file, which can be any image format supported by
9002 libavformat. The width and height of the image file must match those of the
9003 video stream being processed.
9006 Pixels in the provided bitmap image with a value of zero are not
9007 considered part of the logo, non-zero pixels are considered part of
9008 the logo. If you use white (255) for the logo and black (0) for the
9009 rest, you will be safe. For making the filter bitmap, it is
9010 recommended to take a screen capture of a black frame with the logo
9011 visible, and then using a threshold filter followed by the erode
9012 filter once or twice.
9014 If needed, little splotches can be fixed manually. Remember that if
9015 logo pixels are not covered, the filter quality will be much
9016 reduced. Marking too many pixels as part of the logo does not hurt as
9017 much, but it will increase the amount of blurring needed to cover over
9018 the image and will destroy more information than necessary, and extra
9019 pixels will slow things down on a large logo.
9021 @section repeatfields
9023 This filter uses the repeat_field flag from the Video ES headers and hard repeats
9024 fields based on its value.
9026 @section reverse, areverse
9030 Warning: This filter requires memory to buffer the entire clip, so trimming
9033 @subsection Examples
9037 Take the first 5 seconds of a clip, and reverse it.
9045 Rotate video by an arbitrary angle expressed in radians.
9047 The filter accepts the following options:
9049 A description of the optional parameters follows.
9052 Set an expression for the angle by which to rotate the input video
9053 clockwise, expressed as a number of radians. A negative value will
9054 result in a counter-clockwise rotation. By default it is set to "0".
9056 This expression is evaluated for each frame.
9059 Set the output width expression, default value is "iw".
9060 This expression is evaluated just once during configuration.
9063 Set the output height expression, default value is "ih".
9064 This expression is evaluated just once during configuration.
9067 Enable bilinear interpolation if set to 1, a value of 0 disables
9068 it. Default value is 1.
9071 Set the color used to fill the output area not covered by the rotated
9072 image. For the general syntax of this option, check the "Color" section in the
9073 ffmpeg-utils manual. If the special value "none" is selected then no
9074 background is printed (useful for example if the background is never shown).
9076 Default value is "black".
9079 The expressions for the angle and the output size can contain the
9080 following constants and functions:
9084 sequential number of the input frame, starting from 0. It is always NAN
9085 before the first frame is filtered.
9088 time in seconds of the input frame, it is set to 0 when the filter is
9089 configured. It is always NAN before the first frame is filtered.
9093 horizontal and vertical chroma subsample values. For example for the
9094 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9098 the input video width and height
9102 the output width and height, that is the size of the padded area as
9103 specified by the @var{width} and @var{height} expressions
9107 the minimal width/height required for completely containing the input
9108 video rotated by @var{a} radians.
9110 These are only available when computing the @option{out_w} and
9111 @option{out_h} expressions.
9114 @subsection Examples
9118 Rotate the input by PI/6 radians clockwise:
9124 Rotate the input by PI/6 radians counter-clockwise:
9130 Rotate the input by 45 degrees clockwise:
9136 Apply a constant rotation with period T, starting from an angle of PI/3:
9138 rotate=PI/3+2*PI*t/T
9142 Make the input video rotation oscillating with a period of T
9143 seconds and an amplitude of A radians:
9145 rotate=A*sin(2*PI/T*t)
9149 Rotate the video, output size is chosen so that the whole rotating
9150 input video is always completely contained in the output:
9152 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
9156 Rotate the video, reduce the output size so that no background is ever
9159 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
9163 @subsection Commands
9165 The filter supports the following commands:
9169 Set the angle expression.
9170 The command accepts the same syntax of the corresponding option.
9172 If the specified expression is not valid, it is kept at its current
9178 Apply Shape Adaptive Blur.
9180 The filter accepts the following options:
9183 @item luma_radius, lr
9184 Set luma blur filter strength, must be a value in range 0.1-4.0, default
9185 value is 1.0. A greater value will result in a more blurred image, and
9186 in slower processing.
9188 @item luma_pre_filter_radius, lpfr
9189 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
9192 @item luma_strength, ls
9193 Set luma maximum difference between pixels to still be considered, must
9194 be a value in the 0.1-100.0 range, default value is 1.0.
9196 @item chroma_radius, cr
9197 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
9198 greater value will result in a more blurred image, and in slower
9201 @item chroma_pre_filter_radius, cpfr
9202 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
9204 @item chroma_strength, cs
9205 Set chroma maximum difference between pixels to still be considered,
9206 must be a value in the 0.1-100.0 range.
9209 Each chroma option value, if not explicitly specified, is set to the
9210 corresponding luma option value.
9215 Scale (resize) the input video, using the libswscale library.
9217 The scale filter forces the output display aspect ratio to be the same
9218 of the input, by changing the output sample aspect ratio.
9220 If the input image format is different from the format requested by
9221 the next filter, the scale filter will convert the input to the
9225 The filter accepts the following options, or any of the options
9226 supported by the libswscale scaler.
9228 See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for
9229 the complete list of scaler options.
9234 Set the output video dimension expression. Default value is the input
9237 If the value is 0, the input width is used for the output.
9239 If one of the values is -1, the scale filter will use a value that
9240 maintains the aspect ratio of the input image, calculated from the
9241 other specified dimension. If both of them are -1, the input size is
9244 If one of the values is -n with n > 1, the scale filter will also use a value
9245 that maintains the aspect ratio of the input image, calculated from the other
9246 specified dimension. After that it will, however, make sure that the calculated
9247 dimension is divisible by n and adjust the value if necessary.
9249 See below for the list of accepted constants for use in the dimension
9253 Set the interlacing mode. It accepts the following values:
9257 Force interlaced aware scaling.
9260 Do not apply interlaced scaling.
9263 Select interlaced aware scaling depending on whether the source frames
9264 are flagged as interlaced or not.
9267 Default value is @samp{0}.
9270 Set libswscale scaling flags. See
9271 @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the
9272 complete list of values. If not explicitly specified the filter applies
9276 Set the video size. For the syntax of this option, check the
9277 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9279 @item in_color_matrix
9280 @item out_color_matrix
9281 Set in/output YCbCr color space type.
9283 This allows the autodetected value to be overridden as well as allows forcing
9284 a specific value used for the output and encoder.
9286 If not specified, the color space type depends on the pixel format.
9292 Choose automatically.
9295 Format conforming to International Telecommunication Union (ITU)
9296 Recommendation BT.709.
9299 Set color space conforming to the United States Federal Communications
9300 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
9303 Set color space conforming to:
9307 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
9310 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
9313 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
9318 Set color space conforming to SMPTE ST 240:1999.
9323 Set in/output YCbCr sample range.
9325 This allows the autodetected value to be overridden as well as allows forcing
9326 a specific value used for the output and encoder. If not specified, the
9327 range depends on the pixel format. Possible values:
9331 Choose automatically.
9334 Set full range (0-255 in case of 8-bit luma).
9337 Set "MPEG" range (16-235 in case of 8-bit luma).
9340 @item force_original_aspect_ratio
9341 Enable decreasing or increasing output video width or height if necessary to
9342 keep the original aspect ratio. Possible values:
9346 Scale the video as specified and disable this feature.
9349 The output video dimensions will automatically be decreased if needed.
9352 The output video dimensions will automatically be increased if needed.
9356 One useful instance of this option is that when you know a specific device's
9357 maximum allowed resolution, you can use this to limit the output video to
9358 that, while retaining the aspect ratio. For example, device A allows
9359 1280x720 playback, and your video is 1920x800. Using this option (set it to
9360 decrease) and specifying 1280x720 to the command line makes the output
9363 Please note that this is a different thing than specifying -1 for @option{w}
9364 or @option{h}, you still need to specify the output resolution for this option
9369 The values of the @option{w} and @option{h} options are expressions
9370 containing the following constants:
9375 The input width and height
9379 These are the same as @var{in_w} and @var{in_h}.
9383 The output (scaled) width and height
9387 These are the same as @var{out_w} and @var{out_h}
9390 The same as @var{iw} / @var{ih}
9393 input sample aspect ratio
9396 The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
9400 horizontal and vertical input chroma subsample values. For example for the
9401 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9405 horizontal and vertical output chroma subsample values. For example for the
9406 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9409 @subsection Examples
9413 Scale the input video to a size of 200x100
9418 This is equivalent to:
9429 Specify a size abbreviation for the output size:
9434 which can also be written as:
9440 Scale the input to 2x:
9446 The above is the same as:
9452 Scale the input to 2x with forced interlaced scaling:
9454 scale=2*iw:2*ih:interl=1
9458 Scale the input to half size:
9464 Increase the width, and set the height to the same size:
9477 Increase the height, and set the width to 3/2 of the height:
9479 scale=w=3/2*oh:h=3/5*ih
9483 Increase the size, making the size a multiple of the chroma
9486 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
9490 Increase the width to a maximum of 500 pixels,
9491 keeping the same aspect ratio as the input:
9493 scale=w='min(500\, iw*3/2):h=-1'
9497 @subsection Commands
9499 This filter supports the following commands:
9503 Set the output video dimension expression.
9504 The command accepts the same syntax of the corresponding option.
9506 If the specified expression is not valid, it is kept at its current
9512 Scale (resize) the input video, based on a reference video.
9514 See the scale filter for available options, scale2ref supports the same but
9515 uses the reference video instead of the main input as basis.
9517 @subsection Examples
9521 Scale a subtitle stream to match the main video in size before overlaying
9523 'scale2ref[b][a];[a][b]overlay'
9527 @section separatefields
9529 The @code{separatefields} takes a frame-based video input and splits
9530 each frame into its components fields, producing a new half height clip
9531 with twice the frame rate and twice the frame count.
9533 This filter use field-dominance information in frame to decide which
9534 of each pair of fields to place first in the output.
9535 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
9537 @section setdar, setsar
9539 The @code{setdar} filter sets the Display Aspect Ratio for the filter
9542 This is done by changing the specified Sample (aka Pixel) Aspect
9543 Ratio, according to the following equation:
9545 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
9548 Keep in mind that the @code{setdar} filter does not modify the pixel
9549 dimensions of the video frame. Also, the display aspect ratio set by
9550 this filter may be changed by later filters in the filterchain,
9551 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
9554 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
9555 the filter output video.
9557 Note that as a consequence of the application of this filter, the
9558 output display aspect ratio will change according to the equation
9561 Keep in mind that the sample aspect ratio set by the @code{setsar}
9562 filter may be changed by later filters in the filterchain, e.g. if
9563 another "setsar" or a "setdar" filter is applied.
9565 It accepts the following parameters:
9568 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
9569 Set the aspect ratio used by the filter.
9571 The parameter can be a floating point number string, an expression, or
9572 a string of the form @var{num}:@var{den}, where @var{num} and
9573 @var{den} are the numerator and denominator of the aspect ratio. If
9574 the parameter is not specified, it is assumed the value "0".
9575 In case the form "@var{num}:@var{den}" is used, the @code{:} character
9579 Set the maximum integer value to use for expressing numerator and
9580 denominator when reducing the expressed aspect ratio to a rational.
9581 Default value is @code{100}.
9585 The parameter @var{sar} is an expression containing
9586 the following constants:
9590 These are approximated values for the mathematical constants e
9591 (Euler's number), pi (Greek pi), and phi (the golden ratio).
9594 The input width and height.
9597 These are the same as @var{w} / @var{h}.
9600 The input sample aspect ratio.
9603 The input display aspect ratio. It is the same as
9604 (@var{w} / @var{h}) * @var{sar}.
9607 Horizontal and vertical chroma subsample values. For example, for the
9608 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
9611 @subsection Examples
9616 To change the display aspect ratio to 16:9, specify one of the following:
9624 To change the sample aspect ratio to 10:11, specify:
9630 To set a display aspect ratio of 16:9, and specify a maximum integer value of
9631 1000 in the aspect ratio reduction, use the command:
9633 setdar=ratio=16/9:max=1000
9641 Force field for the output video frame.
9643 The @code{setfield} filter marks the interlace type field for the
9644 output frames. It does not change the input frame, but only sets the
9645 corresponding property, which affects how the frame is treated by
9646 following filters (e.g. @code{fieldorder} or @code{yadif}).
9648 The filter accepts the following options:
9653 Available values are:
9657 Keep the same field property.
9660 Mark the frame as bottom-field-first.
9663 Mark the frame as top-field-first.
9666 Mark the frame as progressive.
9672 Show a line containing various information for each input video frame.
9673 The input video is not modified.
9675 The shown line contains a sequence of key/value pairs of the form
9676 @var{key}:@var{value}.
9678 The following values are shown in the output:
9682 The (sequential) number of the input frame, starting from 0.
9685 The Presentation TimeStamp of the input frame, expressed as a number of
9686 time base units. The time base unit depends on the filter input pad.
9689 The Presentation TimeStamp of the input frame, expressed as a number of
9693 The position of the frame in the input stream, or -1 if this information is
9694 unavailable and/or meaningless (for example in case of synthetic video).
9697 The pixel format name.
9700 The sample aspect ratio of the input frame, expressed in the form
9701 @var{num}/@var{den}.
9704 The size of the input frame. For the syntax of this option, check the
9705 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
9708 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
9709 for bottom field first).
9712 This is 1 if the frame is a key frame, 0 otherwise.
9715 The picture type of the input frame ("I" for an I-frame, "P" for a
9716 P-frame, "B" for a B-frame, or "?" for an unknown type).
9717 Also refer to the documentation of the @code{AVPictureType} enum and of
9718 the @code{av_get_picture_type_char} function defined in
9719 @file{libavutil/avutil.h}.
9722 The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
9724 @item plane_checksum
9725 The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
9726 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]".
9729 @section showpalette
9731 Displays the 256 colors palette of each frame. This filter is only relevant for
9732 @var{pal8} pixel format frames.
9734 It accepts the following option:
9738 Set the size of the box used to represent one palette color entry. Default is
9739 @code{30} (for a @code{30x30} pixel box).
9742 @section shuffleplanes
9744 Reorder and/or duplicate video planes.
9746 It accepts the following parameters:
9751 The index of the input plane to be used as the first output plane.
9754 The index of the input plane to be used as the second output plane.
9757 The index of the input plane to be used as the third output plane.
9760 The index of the input plane to be used as the fourth output plane.
9764 The first plane has the index 0. The default is to keep the input unchanged.
9766 Swap the second and third planes of the input:
9768 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
9771 @anchor{signalstats}
9772 @section signalstats
9773 Evaluate various visual metrics that assist in determining issues associated
9774 with the digitization of analog video media.
9776 By default the filter will log these metadata values:
9780 Display the minimal Y value contained within the input frame. Expressed in
9784 Display the Y value at the 10% percentile within the input frame. Expressed in
9788 Display the average Y value within the input frame. Expressed in range of
9792 Display the Y value at the 90% percentile within the input frame. Expressed in
9796 Display the maximum Y value contained within the input frame. Expressed in
9800 Display the minimal U value contained within the input frame. Expressed in
9804 Display the U value at the 10% percentile within the input frame. Expressed in
9808 Display the average U value within the input frame. Expressed in range of
9812 Display the U value at the 90% percentile within the input frame. Expressed in
9816 Display the maximum U value contained within the input frame. Expressed in
9820 Display the minimal V value contained within the input frame. Expressed in
9824 Display the V value at the 10% percentile within the input frame. Expressed in
9828 Display the average V value within the input frame. Expressed in range of
9832 Display the V value at the 90% percentile within the input frame. Expressed in
9836 Display the maximum V value contained within the input frame. Expressed in
9840 Display the minimal saturation value contained within the input frame.
9841 Expressed in range of [0-~181.02].
9844 Display the saturation value at the 10% percentile within the input frame.
9845 Expressed in range of [0-~181.02].
9848 Display the average saturation value within the input frame. Expressed in range
9852 Display the saturation value at the 90% percentile within the input frame.
9853 Expressed in range of [0-~181.02].
9856 Display the maximum saturation value contained within the input frame.
9857 Expressed in range of [0-~181.02].
9860 Display the median value for hue within the input frame. Expressed in range of
9864 Display the average value for hue within the input frame. Expressed in range of
9868 Display the average of sample value difference between all values of the Y
9869 plane in the current frame and corresponding values of the previous input frame.
9870 Expressed in range of [0-255].
9873 Display the average of sample value difference between all values of the U
9874 plane in the current frame and corresponding values of the previous input frame.
9875 Expressed in range of [0-255].
9878 Display the average of sample value difference between all values of the V
9879 plane in the current frame and corresponding values of the previous input frame.
9880 Expressed in range of [0-255].
9883 The filter accepts the following options:
9889 @option{stat} specify an additional form of image analysis.
9890 @option{out} output video with the specified type of pixel highlighted.
9892 Both options accept the following values:
9896 Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel
9897 unlike the neighboring pixels of the same field. Examples of temporal outliers
9898 include the results of video dropouts, head clogs, or tape tracking issues.
9901 Identify @var{vertical line repetition}. Vertical line repetition includes
9902 similar rows of pixels within a frame. In born-digital video vertical line
9903 repetition is common, but this pattern is uncommon in video digitized from an
9904 analog source. When it occurs in video that results from the digitization of an
9905 analog source it can indicate concealment from a dropout compensator.
9908 Identify pixels that fall outside of legal broadcast range.
9912 Set the highlight color for the @option{out} option. The default color is
9916 @subsection Examples
9920 Output data of various video metrics:
9922 ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
9926 Output specific data about the minimum and maximum values of the Y plane per frame:
9928 ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
9932 Playback video while highlighting pixels that are outside of broadcast range in red.
9934 ffplay example.mov -vf signalstats="out=brng:color=red"
9938 Playback video with signalstats metadata drawn over the frame.
9940 ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
9943 The contents of signalstat_drawtext.txt used in the command are:
9946 Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@})
9947 U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@})
9948 V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@})
9949 saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@}
9957 Blur the input video without impacting the outlines.
9959 It accepts the following options:
9962 @item luma_radius, lr
9963 Set the luma radius. The option value must be a float number in
9964 the range [0.1,5.0] that specifies the variance of the gaussian filter
9965 used to blur the image (slower if larger). Default value is 1.0.
9967 @item luma_strength, ls
9968 Set the luma strength. The option value must be a float number
9969 in the range [-1.0,1.0] that configures the blurring. A value included
9970 in [0.0,1.0] will blur the image whereas a value included in
9971 [-1.0,0.0] will sharpen the image. Default value is 1.0.
9973 @item luma_threshold, lt
9974 Set the luma threshold used as a coefficient to determine
9975 whether a pixel should be blurred or not. The option value must be an
9976 integer in the range [-30,30]. A value of 0 will filter all the image,
9977 a value included in [0,30] will filter flat areas and a value included
9978 in [-30,0] will filter edges. Default value is 0.
9980 @item chroma_radius, cr
9981 Set the chroma radius. The option value must be a float number in
9982 the range [0.1,5.0] that specifies the variance of the gaussian filter
9983 used to blur the image (slower if larger). Default value is 1.0.
9985 @item chroma_strength, cs
9986 Set the chroma strength. The option value must be a float number
9987 in the range [-1.0,1.0] that configures the blurring. A value included
9988 in [0.0,1.0] will blur the image whereas a value included in
9989 [-1.0,0.0] will sharpen the image. Default value is 1.0.
9991 @item chroma_threshold, ct
9992 Set the chroma threshold used as a coefficient to determine
9993 whether a pixel should be blurred or not. The option value must be an
9994 integer in the range [-30,30]. A value of 0 will filter all the image,
9995 a value included in [0,30] will filter flat areas and a value included
9996 in [-30,0] will filter edges. Default value is 0.
9999 If a chroma option is not explicitly set, the corresponding luma value
10004 Obtain the SSIM (Structural SImilarity Metric) between two input videos.
10006 This filter takes in input two input videos, the first input is
10007 considered the "main" source and is passed unchanged to the
10008 output. The second input is used as a "reference" video for computing
10011 Both video inputs must have the same resolution and pixel format for
10012 this filter to work correctly. Also it assumes that both inputs
10013 have the same number of frames, which are compared one by one.
10015 The filter stores the calculated SSIM of each frame.
10017 The description of the accepted parameters follows.
10020 @item stats_file, f
10021 If specified the filter will use the named file to save the SSIM of
10022 each individual frame.
10025 The file printed if @var{stats_file} is selected, contains a sequence of
10026 key/value pairs of the form @var{key}:@var{value} for each compared
10029 A description of each shown parameter follows:
10033 sequential number of the input frame, starting from 1
10035 @item Y, U, V, R, G, B
10036 SSIM of the compared frames for the component specified by the suffix.
10039 SSIM of the compared frames for the whole frame.
10042 Same as above but in dB representation.
10047 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
10048 [main][ref] ssim="stats_file=stats.log" [out]
10051 On this example the input file being processed is compared with the
10052 reference file @file{ref_movie.mpg}. The SSIM of each individual frame
10053 is stored in @file{stats.log}.
10055 Another example with both psnr and ssim at same time:
10057 ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
10062 Convert between different stereoscopic image formats.
10064 The filters accept the following options:
10068 Set stereoscopic image format of input.
10070 Available values for input image formats are:
10073 side by side parallel (left eye left, right eye right)
10076 side by side crosseye (right eye left, left eye right)
10079 side by side parallel with half width resolution
10080 (left eye left, right eye right)
10083 side by side crosseye with half width resolution
10084 (right eye left, left eye right)
10087 above-below (left eye above, right eye below)
10090 above-below (right eye above, left eye below)
10093 above-below with half height resolution
10094 (left eye above, right eye below)
10097 above-below with half height resolution
10098 (right eye above, left eye below)
10101 alternating frames (left eye first, right eye second)
10104 alternating frames (right eye first, left eye second)
10107 interleaved rows (left eye has top row, right eye starts on next row)
10110 interleaved rows (right eye has top row, left eye starts on next row)
10112 Default value is @samp{sbsl}.
10116 Set stereoscopic image format of output.
10118 Available values for output image formats are all the input formats as well as:
10121 anaglyph red/blue gray
10122 (red filter on left eye, blue filter on right eye)
10125 anaglyph red/green gray
10126 (red filter on left eye, green filter on right eye)
10129 anaglyph red/cyan gray
10130 (red filter on left eye, cyan filter on right eye)
10133 anaglyph red/cyan half colored
10134 (red filter on left eye, cyan filter on right eye)
10137 anaglyph red/cyan color
10138 (red filter on left eye, cyan filter on right eye)
10141 anaglyph red/cyan color optimized with the least squares projection of dubois
10142 (red filter on left eye, cyan filter on right eye)
10145 anaglyph green/magenta gray
10146 (green filter on left eye, magenta filter on right eye)
10149 anaglyph green/magenta half colored
10150 (green filter on left eye, magenta filter on right eye)
10153 anaglyph green/magenta colored
10154 (green filter on left eye, magenta filter on right eye)
10157 anaglyph green/magenta color optimized with the least squares projection of dubois
10158 (green filter on left eye, magenta filter on right eye)
10161 anaglyph yellow/blue gray
10162 (yellow filter on left eye, blue filter on right eye)
10165 anaglyph yellow/blue half colored
10166 (yellow filter on left eye, blue filter on right eye)
10169 anaglyph yellow/blue colored
10170 (yellow filter on left eye, blue filter on right eye)
10173 anaglyph yellow/blue color optimized with the least squares projection of dubois
10174 (yellow filter on left eye, blue filter on right eye)
10177 mono output (left eye only)
10180 mono output (right eye only)
10183 checkerboard, left eye first
10186 checkerboard, right eye first
10189 interleaved columns, left eye first
10192 interleaved columns, right eye first
10195 Default value is @samp{arcd}.
10198 @subsection Examples
10202 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
10208 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
10217 Apply a simple postprocessing filter that compresses and decompresses the image
10218 at several (or - in the case of @option{quality} level @code{6} - all) shifts
10219 and average the results.
10221 The filter accepts the following options:
10225 Set quality. This option defines the number of levels for averaging. It accepts
10226 an integer in the range 0-6. If set to @code{0}, the filter will have no
10227 effect. A value of @code{6} means the higher quality. For each increment of
10228 that value the speed drops by a factor of approximately 2. Default value is
10232 Force a constant quantization parameter. If not set, the filter will use the QP
10233 from the video stream (if available).
10236 Set thresholding mode. Available modes are:
10240 Set hard thresholding (default).
10242 Set soft thresholding (better de-ringing effect, but likely blurrier).
10245 @item use_bframe_qp
10246 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
10247 option may cause flicker since the B-Frames have often larger QP. Default is
10248 @code{0} (not enabled).
10254 Draw subtitles on top of input video using the libass library.
10256 To enable compilation of this filter you need to configure FFmpeg with
10257 @code{--enable-libass}. This filter also requires a build with libavcodec and
10258 libavformat to convert the passed subtitles file to ASS (Advanced Substation
10259 Alpha) subtitles format.
10261 The filter accepts the following options:
10265 Set the filename of the subtitle file to read. It must be specified.
10267 @item original_size
10268 Specify the size of the original video, the video for which the ASS file
10269 was composed. For the syntax of this option, check the
10270 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10271 Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
10272 correctly scale the fonts if the aspect ratio has been changed.
10275 Set a directory path containing fonts that can be used by the filter.
10276 These fonts will be used in addition to whatever the font provider uses.
10279 Set subtitles input character encoding. @code{subtitles} filter only. Only
10280 useful if not UTF-8.
10282 @item stream_index, si
10283 Set subtitles stream index. @code{subtitles} filter only.
10286 Override default style or script info parameters of the subtitles. It accepts a
10287 string containing ASS style format @code{KEY=VALUE} couples separated by ",".
10290 If the first key is not specified, it is assumed that the first value
10291 specifies the @option{filename}.
10293 For example, to render the file @file{sub.srt} on top of the input
10294 video, use the command:
10299 which is equivalent to:
10301 subtitles=filename=sub.srt
10304 To render the default subtitles stream from file @file{video.mkv}, use:
10306 subtitles=video.mkv
10309 To render the second subtitles stream from that file, use:
10311 subtitles=video.mkv:si=1
10314 To make the subtitles stream from @file{sub.srt} appear in transparent green
10315 @code{DejaVu Serif}, use:
10317 subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HAA00FF00'
10320 @section super2xsai
10322 Scale the input by 2x and smooth using the Super2xSaI (Scale and
10323 Interpolate) pixel art scaling algorithm.
10325 Useful for enlarging pixel art images without reducing sharpness.
10332 Apply telecine process to the video.
10334 This filter accepts the following options:
10343 The default value is @code{top}.
10347 A string of numbers representing the pulldown pattern you wish to apply.
10348 The default value is @code{23}.
10352 Some typical patterns:
10357 24p: 2332 (preferred)
10364 24p: 222222222223 ("Euro pulldown")
10370 Select the most representative frame in a given sequence of consecutive frames.
10372 The filter accepts the following options:
10376 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
10377 will pick one of them, and then handle the next batch of @var{n} frames until
10378 the end. Default is @code{100}.
10381 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
10382 value will result in a higher memory usage, so a high value is not recommended.
10384 @subsection Examples
10388 Extract one picture each 50 frames:
10394 Complete example of a thumbnail creation with @command{ffmpeg}:
10396 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
10402 Tile several successive frames together.
10404 The filter accepts the following options:
10409 Set the grid size (i.e. the number of lines and columns). For the syntax of
10410 this option, check the
10411 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
10414 Set the maximum number of frames to render in the given area. It must be less
10415 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
10416 the area will be used.
10419 Set the outer border margin in pixels.
10422 Set the inner border thickness (i.e. the number of pixels between frames). For
10423 more advanced padding options (such as having different values for the edges),
10424 refer to the pad video filter.
10427 Specify the color of the unused area. For the syntax of this option, check the
10428 "Color" section in the ffmpeg-utils manual. The default value of @var{color}
10432 @subsection Examples
10436 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
10438 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
10440 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
10441 duplicating each output frame to accommodate the originally detected frame
10445 Display @code{5} pictures in an area of @code{3x2} frames,
10446 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
10447 mixed flat and named options:
10449 tile=3x2:nb_frames=5:padding=7:margin=2
10453 @section tinterlace
10455 Perform various types of temporal field interlacing.
10457 Frames are counted starting from 1, so the first input frame is
10460 The filter accepts the following options:
10465 Specify the mode of the interlacing. This option can also be specified
10466 as a value alone. See below for a list of values for this option.
10468 Available values are:
10472 Move odd frames into the upper field, even into the lower field,
10473 generating a double height frame at half frame rate.
10477 Frame 1 Frame 2 Frame 3 Frame 4
10479 11111 22222 33333 44444
10480 11111 22222 33333 44444
10481 11111 22222 33333 44444
10482 11111 22222 33333 44444
10496 Only output even frames, odd frames are dropped, generating a frame with
10497 unchanged height at half frame rate.
10502 Frame 1 Frame 2 Frame 3 Frame 4
10504 11111 22222 33333 44444
10505 11111 22222 33333 44444
10506 11111 22222 33333 44444
10507 11111 22222 33333 44444
10517 Only output odd frames, even frames are dropped, generating a frame with
10518 unchanged height at half frame rate.
10523 Frame 1 Frame 2 Frame 3 Frame 4
10525 11111 22222 33333 44444
10526 11111 22222 33333 44444
10527 11111 22222 33333 44444
10528 11111 22222 33333 44444
10538 Expand each frame to full height, but pad alternate lines with black,
10539 generating a frame with double height at the same input frame rate.
10544 Frame 1 Frame 2 Frame 3 Frame 4
10546 11111 22222 33333 44444
10547 11111 22222 33333 44444
10548 11111 22222 33333 44444
10549 11111 22222 33333 44444
10552 11111 ..... 33333 .....
10553 ..... 22222 ..... 44444
10554 11111 ..... 33333 .....
10555 ..... 22222 ..... 44444
10556 11111 ..... 33333 .....
10557 ..... 22222 ..... 44444
10558 11111 ..... 33333 .....
10559 ..... 22222 ..... 44444
10563 @item interleave_top, 4
10564 Interleave the upper field from odd frames with the lower field from
10565 even frames, generating a frame with unchanged height at half frame rate.
10570 Frame 1 Frame 2 Frame 3 Frame 4
10572 11111<- 22222 33333<- 44444
10573 11111 22222<- 33333 44444<-
10574 11111<- 22222 33333<- 44444
10575 11111 22222<- 33333 44444<-
10585 @item interleave_bottom, 5
10586 Interleave the lower field from odd frames with the upper field from
10587 even frames, generating a frame with unchanged height at half frame rate.
10592 Frame 1 Frame 2 Frame 3 Frame 4
10594 11111 22222<- 33333 44444<-
10595 11111<- 22222 33333<- 44444
10596 11111 22222<- 33333 44444<-
10597 11111<- 22222 33333<- 44444
10607 @item interlacex2, 6
10608 Double frame rate with unchanged height. Frames are inserted each
10609 containing the second temporal field from the previous input frame and
10610 the first temporal field from the next input frame. This mode relies on
10611 the top_field_first flag. Useful for interlaced video displays with no
10612 field synchronisation.
10617 Frame 1 Frame 2 Frame 3 Frame 4
10619 11111 22222 33333 44444
10620 11111 22222 33333 44444
10621 11111 22222 33333 44444
10622 11111 22222 33333 44444
10625 11111 22222 22222 33333 33333 44444 44444
10626 11111 11111 22222 22222 33333 33333 44444
10627 11111 22222 22222 33333 33333 44444 44444
10628 11111 11111 22222 22222 33333 33333 44444
10634 Numeric values are deprecated but are accepted for backward
10635 compatibility reasons.
10637 Default mode is @code{merge}.
10640 Specify flags influencing the filter process.
10642 Available value for @var{flags} is:
10645 @item low_pass_filter, vlfp
10646 Enable vertical low-pass filtering in the filter.
10647 Vertical low-pass filtering is required when creating an interlaced
10648 destination from a progressive source which contains high-frequency
10649 vertical detail. Filtering will reduce interlace 'twitter' and Moire
10652 Vertical low-pass filtering can only be enabled for @option{mode}
10653 @var{interleave_top} and @var{interleave_bottom}.
10660 Transpose rows with columns in the input video and optionally flip it.
10662 It accepts the following parameters:
10667 Specify the transposition direction.
10669 Can assume the following values:
10671 @item 0, 4, cclock_flip
10672 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
10680 Rotate by 90 degrees clockwise, that is:
10688 Rotate by 90 degrees counterclockwise, that is:
10695 @item 3, 7, clock_flip
10696 Rotate by 90 degrees clockwise and vertically flip, that is:
10704 For values between 4-7, the transposition is only done if the input
10705 video geometry is portrait and not landscape. These values are
10706 deprecated, the @code{passthrough} option should be used instead.
10708 Numerical values are deprecated, and should be dropped in favor of
10709 symbolic constants.
10712 Do not apply the transposition if the input geometry matches the one
10713 specified by the specified value. It accepts the following values:
10716 Always apply transposition.
10718 Preserve portrait geometry (when @var{height} >= @var{width}).
10720 Preserve landscape geometry (when @var{width} >= @var{height}).
10723 Default value is @code{none}.
10726 For example to rotate by 90 degrees clockwise and preserve portrait
10729 transpose=dir=1:passthrough=portrait
10732 The command above can also be specified as:
10734 transpose=1:portrait
10738 Trim the input so that the output contains one continuous subpart of the input.
10740 It accepts the following parameters:
10743 Specify the time of the start of the kept section, i.e. the frame with the
10744 timestamp @var{start} will be the first frame in the output.
10747 Specify the time of the first frame that will be dropped, i.e. the frame
10748 immediately preceding the one with the timestamp @var{end} will be the last
10749 frame in the output.
10752 This is the same as @var{start}, except this option sets the start timestamp
10753 in timebase units instead of seconds.
10756 This is the same as @var{end}, except this option sets the end timestamp
10757 in timebase units instead of seconds.
10760 The maximum duration of the output in seconds.
10763 The number of the first frame that should be passed to the output.
10766 The number of the first frame that should be dropped.
10769 @option{start}, @option{end}, and @option{duration} are expressed as time
10770 duration specifications; see
10771 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
10772 for the accepted syntax.
10774 Note that the first two sets of the start/end options and the @option{duration}
10775 option look at the frame timestamp, while the _frame variants simply count the
10776 frames that pass through the filter. Also note that this filter does not modify
10777 the timestamps. If you wish for the output timestamps to start at zero, insert a
10778 setpts filter after the trim filter.
10780 If multiple start or end options are set, this filter tries to be greedy and
10781 keep all the frames that match at least one of the specified constraints. To keep
10782 only the part that matches all the constraints at once, chain multiple trim
10785 The defaults are such that all the input is kept. So it is possible to set e.g.
10786 just the end values to keep everything before the specified time.
10791 Drop everything except the second minute of input:
10793 ffmpeg -i INPUT -vf trim=60:120
10797 Keep only the first second:
10799 ffmpeg -i INPUT -vf trim=duration=1
10808 Sharpen or blur the input video.
10810 It accepts the following parameters:
10813 @item luma_msize_x, lx
10814 Set the luma matrix horizontal size. It must be an odd integer between
10815 3 and 63. The default value is 5.
10817 @item luma_msize_y, ly
10818 Set the luma matrix vertical size. It must be an odd integer between 3
10819 and 63. The default value is 5.
10821 @item luma_amount, la
10822 Set the luma effect strength. It must be a floating point number, reasonable
10823 values lay between -1.5 and 1.5.
10825 Negative values will blur the input video, while positive values will
10826 sharpen it, a value of zero will disable the effect.
10828 Default value is 1.0.
10830 @item chroma_msize_x, cx
10831 Set the chroma matrix horizontal size. It must be an odd integer
10832 between 3 and 63. The default value is 5.
10834 @item chroma_msize_y, cy
10835 Set the chroma matrix vertical size. It must be an odd integer
10836 between 3 and 63. The default value is 5.
10838 @item chroma_amount, ca
10839 Set the chroma effect strength. It must be a floating point number, reasonable
10840 values lay between -1.5 and 1.5.
10842 Negative values will blur the input video, while positive values will
10843 sharpen it, a value of zero will disable the effect.
10845 Default value is 0.0.
10848 If set to 1, specify using OpenCL capabilities, only available if
10849 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
10853 All parameters are optional and default to the equivalent of the
10854 string '5:5:1.0:5:5:0.0'.
10856 @subsection Examples
10860 Apply strong luma sharpen effect:
10862 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
10866 Apply a strong blur of both luma and chroma parameters:
10868 unsharp=7:7:-2:7:7:-2
10874 Apply ultra slow/simple postprocessing filter that compresses and decompresses
10875 the image at several (or - in the case of @option{quality} level @code{8} - all)
10876 shifts and average the results.
10878 The way this differs from the behavior of spp is that uspp actually encodes &
10879 decodes each case with libavcodec Snow, whereas spp uses a simplified intra only 8x8
10880 DCT similar to MJPEG.
10882 The filter accepts the following options:
10886 Set quality. This option defines the number of levels for averaging. It accepts
10887 an integer in the range 0-8. If set to @code{0}, the filter will have no
10888 effect. A value of @code{8} means the higher quality. For each increment of
10889 that value the speed drops by a factor of approximately 2. Default value is
10893 Force a constant quantization parameter. If not set, the filter will use the QP
10894 from the video stream (if available).
10897 @section vectorscope
10899 Display 2 color component values in the two dimensional graph (which is called
10902 This filter accepts the following options:
10906 Set vectorscope mode.
10908 It accepts the following values:
10911 Gray values are displayed on graph, higher brightness means more pixels have
10912 same component color value on location in graph. This is the default mode.
10915 Gray values are displayed on graph. Surrounding pixels values which are not
10916 present in video frame are drawn in gradient of 2 color components which are
10917 set by option @code{x} and @code{y}.
10920 Actual color components values present in video frame are displayed on graph.
10923 Similar as color2 but higher frequency of same values @code{x} and @code{y}
10924 on graph increases value of another color component, which is luminance by
10925 default values of @code{x} and @code{y}.
10928 Actual colors present in video frame are displayed on graph. If two different
10929 colors map to same position on graph then color with higher value of component
10930 not present in graph is picked.
10934 Set which color component will be represented on X-axis. Default is @code{1}.
10937 Set which color component will be represented on Y-axis. Default is @code{2}.
10940 Set intensity, used by modes: gray, color and color3 for increasing brightness
10941 of color component which represents frequency of (X, Y) location in graph.
10946 No envelope, this is default.
10949 Instant envelope, even darkest single pixel will be clearly highlighted.
10952 Hold maximum and minimum values presented in graph over time. This way you
10953 can still spot out of range values without constantly looking at vectorscope.
10956 Peak and instant envelope combined together.
10960 @anchor{vidstabdetect}
10961 @section vidstabdetect
10963 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
10964 @ref{vidstabtransform} for pass 2.
10966 This filter generates a file with relative translation and rotation
10967 transform information about subsequent frames, which is then used by
10968 the @ref{vidstabtransform} filter.
10970 To enable compilation of this filter you need to configure FFmpeg with
10971 @code{--enable-libvidstab}.
10973 This filter accepts the following options:
10977 Set the path to the file used to write the transforms information.
10978 Default value is @file{transforms.trf}.
10981 Set how shaky the video is and how quick the camera is. It accepts an
10982 integer in the range 1-10, a value of 1 means little shakiness, a
10983 value of 10 means strong shakiness. Default value is 5.
10986 Set the accuracy of the detection process. It must be a value in the
10987 range 1-15. A value of 1 means low accuracy, a value of 15 means high
10988 accuracy. Default value is 15.
10991 Set stepsize of the search process. The region around minimum is
10992 scanned with 1 pixel resolution. Default value is 6.
10995 Set minimum contrast. Below this value a local measurement field is
10996 discarded. Must be a floating point value in the range 0-1. Default
11000 Set reference frame number for tripod mode.
11002 If enabled, the motion of the frames is compared to a reference frame
11003 in the filtered stream, identified by the specified number. The idea
11004 is to compensate all movements in a more-or-less static scene and keep
11005 the camera view absolutely still.
11007 If set to 0, it is disabled. The frames are counted starting from 1.
11010 Show fields and transforms in the resulting frames. It accepts an
11011 integer in the range 0-2. Default value is 0, which disables any
11015 @subsection Examples
11019 Use default values:
11025 Analyze strongly shaky movie and put the results in file
11026 @file{mytransforms.trf}:
11028 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
11032 Visualize the result of internal transformations in the resulting
11035 vidstabdetect=show=1
11039 Analyze a video with medium shakiness using @command{ffmpeg}:
11041 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
11045 @anchor{vidstabtransform}
11046 @section vidstabtransform
11048 Video stabilization/deshaking: pass 2 of 2,
11049 see @ref{vidstabdetect} for pass 1.
11051 Read a file with transform information for each frame and
11052 apply/compensate them. Together with the @ref{vidstabdetect}
11053 filter this can be used to deshake videos. See also
11054 @url{http://public.hronopik.de/vid.stab}. It is important to also use
11055 the @ref{unsharp} filter, see below.
11057 To enable compilation of this filter you need to configure FFmpeg with
11058 @code{--enable-libvidstab}.
11060 @subsection Options
11064 Set path to the file used to read the transforms. Default value is
11065 @file{transforms.trf}.
11068 Set the number of frames (value*2 + 1) used for lowpass filtering the
11069 camera movements. Default value is 10.
11071 For example a number of 10 means that 21 frames are used (10 in the
11072 past and 10 in the future) to smoothen the motion in the video. A
11073 larger value leads to a smoother video, but limits the acceleration of
11074 the camera (pan/tilt movements). 0 is a special case where a static
11075 camera is simulated.
11078 Set the camera path optimization algorithm.
11080 Accepted values are:
11083 gaussian kernel low-pass filter on camera motion (default)
11085 averaging on transformations
11089 Set maximal number of pixels to translate frames. Default value is -1,
11093 Set maximal angle in radians (degree*PI/180) to rotate frames. Default
11094 value is -1, meaning no limit.
11097 Specify how to deal with borders that may be visible due to movement
11100 Available values are:
11103 keep image information from previous frame (default)
11105 fill the border black
11109 Invert transforms if set to 1. Default value is 0.
11112 Consider transforms as relative to previous frame if set to 1,
11113 absolute if set to 0. Default value is 0.
11116 Set percentage to zoom. A positive value will result in a zoom-in
11117 effect, a negative value in a zoom-out effect. Default value is 0 (no
11121 Set optimal zooming to avoid borders.
11123 Accepted values are:
11128 optimal static zoom value is determined (only very strong movements
11129 will lead to visible borders) (default)
11131 optimal adaptive zoom value is determined (no borders will be
11132 visible), see @option{zoomspeed}
11135 Note that the value given at zoom is added to the one calculated here.
11138 Set percent to zoom maximally each frame (enabled when
11139 @option{optzoom} is set to 2). Range is from 0 to 5, default value is
11143 Specify type of interpolation.
11145 Available values are:
11150 linear only horizontal
11152 linear in both directions (default)
11154 cubic in both directions (slow)
11158 Enable virtual tripod mode if set to 1, which is equivalent to
11159 @code{relative=0:smoothing=0}. Default value is 0.
11161 Use also @code{tripod} option of @ref{vidstabdetect}.
11164 Increase log verbosity if set to 1. Also the detected global motions
11165 are written to the temporary file @file{global_motions.trf}. Default
11169 @subsection Examples
11173 Use @command{ffmpeg} for a typical stabilization with default values:
11175 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
11178 Note the use of the @ref{unsharp} filter which is always recommended.
11181 Zoom in a bit more and load transform data from a given file:
11183 vidstabtransform=zoom=5:input="mytransforms.trf"
11187 Smoothen the video even more:
11189 vidstabtransform=smoothing=30
11195 Flip the input video vertically.
11197 For example, to vertically flip a video with @command{ffmpeg}:
11199 ffmpeg -i in.avi -vf "vflip" out.avi
11205 Make or reverse a natural vignetting effect.
11207 The filter accepts the following options:
11211 Set lens angle expression as a number of radians.
11213 The value is clipped in the @code{[0,PI/2]} range.
11215 Default value: @code{"PI/5"}
11219 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
11223 Set forward/backward mode.
11225 Available modes are:
11228 The larger the distance from the central point, the darker the image becomes.
11231 The larger the distance from the central point, the brighter the image becomes.
11232 This can be used to reverse a vignette effect, though there is no automatic
11233 detection to extract the lens @option{angle} and other settings (yet). It can
11234 also be used to create a burning effect.
11237 Default value is @samp{forward}.
11240 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
11242 It accepts the following values:
11245 Evaluate expressions only once during the filter initialization.
11248 Evaluate expressions for each incoming frame. This is way slower than the
11249 @samp{init} mode since it requires all the scalers to be re-computed, but it
11250 allows advanced dynamic expressions.
11253 Default value is @samp{init}.
11256 Set dithering to reduce the circular banding effects. Default is @code{1}
11260 Set vignette aspect. This setting allows one to adjust the shape of the vignette.
11261 Setting this value to the SAR of the input will make a rectangular vignetting
11262 following the dimensions of the video.
11264 Default is @code{1/1}.
11267 @subsection Expressions
11269 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
11270 following parameters.
11275 input width and height
11278 the number of input frame, starting from 0
11281 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
11282 @var{TB} units, NAN if undefined
11285 frame rate of the input video, NAN if the input frame rate is unknown
11288 the PTS (Presentation TimeStamp) of the filtered video frame,
11289 expressed in seconds, NAN if undefined
11292 time base of the input video
11296 @subsection Examples
11300 Apply simple strong vignetting effect:
11306 Make a flickering vignetting:
11308 vignette='PI/4+random(1)*PI/50':eval=frame
11314 Stack input videos vertically.
11316 All streams must be of same pixel format and of same width.
11318 Note that this filter is faster than using @ref{overlay} and @ref{pad} filter
11319 to create same output.
11321 The filter accept the following option:
11325 Set number of input streams. Default is 2.
11330 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
11331 Deinterlacing Filter").
11333 Based on the process described by Martin Weston for BBC R&D, and
11334 implemented based on the de-interlace algorithm written by Jim
11335 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
11336 uses filter coefficients calculated by BBC R&D.
11338 There are two sets of filter coefficients, so called "simple":
11339 and "complex". Which set of filter coefficients is used can
11340 be set by passing an optional parameter:
11344 Set the interlacing filter coefficients. Accepts one of the following values:
11348 Simple filter coefficient set.
11350 More-complex filter coefficient set.
11352 Default value is @samp{complex}.
11355 Specify which frames to deinterlace. Accept one of the following values:
11359 Deinterlace all frames,
11361 Only deinterlace frames marked as interlaced.
11364 Default value is @samp{all}.
11368 Video waveform monitor.
11370 The waveform monitor plots color component intensity. By default luminance
11371 only. Each column of the waveform corresponds to a column of pixels in the
11374 It accepts the following options:
11378 Can be either @code{row}, or @code{column}. Default is @code{column}.
11379 In row mode, the graph on the left side represents color component value 0 and
11380 the right side represents value = 255. In column mode, the top side represents
11381 color component value = 0 and bottom side represents value = 255.
11384 Set intensity. Smaller values are useful to find out how many values of the same
11385 luminance are distributed across input rows/columns.
11386 Default value is @code{0.04}. Allowed range is [0, 1].
11389 Set mirroring mode. @code{0} means unmirrored, @code{1} means mirrored.
11390 In mirrored mode, higher values will be represented on the left
11391 side for @code{row} mode and at the top for @code{column} mode. Default is
11392 @code{1} (mirrored).
11396 It accepts the following values:
11399 Presents information identical to that in the @code{parade}, except
11400 that the graphs representing color components are superimposed directly
11403 This display mode makes it easier to spot relative differences or similarities
11404 in overlapping areas of the color components that are supposed to be identical,
11405 such as neutral whites, grays, or blacks.
11408 Display separate graph for the color components side by side in
11409 @code{row} mode or one below the other in @code{column} mode.
11411 Using this display mode makes it easy to spot color casts in the highlights
11412 and shadows of an image, by comparing the contours of the top and the bottom
11413 graphs of each waveform. Since whites, grays, and blacks are characterized
11414 by exactly equal amounts of red, green, and blue, neutral areas of the picture
11415 should display three waveforms of roughly equal width/height. If not, the
11416 correction is easy to perform by making level adjustments the three waveforms.
11418 Default is @code{parade}.
11420 @item components, c
11421 Set which color components to display. Default is 1, which means only luminance
11422 or red color component if input is in RGB colorspace. If is set for example to
11423 7 it will display all 3 (if) available color components.
11428 No envelope, this is default.
11431 Instant envelope, minimum and maximum values presented in graph will be easily
11432 visible even with small @code{step} value.
11435 Hold minimum and maximum values presented in graph across time. This way you
11436 can still spot out of range values without constantly looking at waveforms.
11439 Peak and instant envelope combined together.
11445 No filtering, this is default.
11448 Luma and chroma combined together.
11451 Similar as above, but shows difference between blue and red chroma.
11454 Displays only chroma.
11457 Similar as above, but shows difference between blue and red chroma.
11460 Displays actual color value on waveform.
11465 Apply the xBR high-quality magnification filter which is designed for pixel
11466 art. It follows a set of edge-detection rules, see
11467 @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}.
11469 It accepts the following option:
11473 Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
11474 @code{3xBR} and @code{4} for @code{4xBR}.
11475 Default is @code{3}.
11481 Deinterlace the input video ("yadif" means "yet another deinterlacing
11484 It accepts the following parameters:
11490 The interlacing mode to adopt. It accepts one of the following values:
11493 @item 0, send_frame
11494 Output one frame for each frame.
11495 @item 1, send_field
11496 Output one frame for each field.
11497 @item 2, send_frame_nospatial
11498 Like @code{send_frame}, but it skips the spatial interlacing check.
11499 @item 3, send_field_nospatial
11500 Like @code{send_field}, but it skips the spatial interlacing check.
11503 The default value is @code{send_frame}.
11506 The picture field parity assumed for the input interlaced video. It accepts one
11507 of the following values:
11511 Assume the top field is first.
11513 Assume the bottom field is first.
11515 Enable automatic detection of field parity.
11518 The default value is @code{auto}.
11519 If the interlacing is unknown or the decoder does not export this information,
11520 top field first will be assumed.
11523 Specify which frames to deinterlace. Accept one of the following
11528 Deinterlace all frames.
11529 @item 1, interlaced
11530 Only deinterlace frames marked as interlaced.
11533 The default value is @code{all}.
11538 Apply Zoom & Pan effect.
11540 This filter accepts the following options:
11544 Set the zoom expression. Default is 1.
11548 Set the x and y expression. Default is 0.
11551 Set the duration expression in number of frames.
11552 This sets for how many number of frames effect will last for
11553 single input image.
11556 Set the output image size, default is 'hd720'.
11559 Each expression can contain the following constants:
11578 Output frame count.
11582 Last calculated 'x' and 'y' position from 'x' and 'y' expression
11583 for current input frame.
11587 'x' and 'y' of last output frame of previous input frame or 0 when there was
11588 not yet such frame (first input frame).
11591 Last calculated zoom from 'z' expression for current input frame.
11594 Last calculated zoom of last output frame of previous input frame.
11597 Number of output frames for current input frame. Calculated from 'd' expression
11598 for each input frame.
11601 number of output frames created for previous input frame
11604 Rational number: input width / input height
11607 sample aspect ratio
11610 display aspect ratio
11614 @subsection Examples
11618 Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
11620 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
11624 Zoom-in up to 1.5 and pan always at center of picture:
11626 zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
11630 @c man end VIDEO FILTERS
11632 @chapter Video Sources
11633 @c man begin VIDEO SOURCES
11635 Below is a description of the currently available video sources.
11639 Buffer video frames, and make them available to the filter chain.
11641 This source is mainly intended for a programmatic use, in particular
11642 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
11644 It accepts the following parameters:
11649 Specify the size (width and height) of the buffered video frames. For the
11650 syntax of this option, check the
11651 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11654 The input video width.
11657 The input video height.
11660 A string representing the pixel format of the buffered video frames.
11661 It may be a number corresponding to a pixel format, or a pixel format
11665 Specify the timebase assumed by the timestamps of the buffered frames.
11668 Specify the frame rate expected for the video stream.
11670 @item pixel_aspect, sar
11671 The sample (pixel) aspect ratio of the input video.
11674 Specify the optional parameters to be used for the scale filter which
11675 is automatically inserted when an input change is detected in the
11676 input size or format.
11681 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
11684 will instruct the source to accept video frames with size 320x240 and
11685 with format "yuv410p", assuming 1/24 as the timestamps timebase and
11686 square pixels (1:1 sample aspect ratio).
11687 Since the pixel format with name "yuv410p" corresponds to the number 6
11688 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
11689 this example corresponds to:
11691 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
11694 Alternatively, the options can be specified as a flat string, but this
11695 syntax is deprecated:
11697 @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}]
11701 Create a pattern generated by an elementary cellular automaton.
11703 The initial state of the cellular automaton can be defined through the
11704 @option{filename}, and @option{pattern} options. If such options are
11705 not specified an initial state is created randomly.
11707 At each new frame a new row in the video is filled with the result of
11708 the cellular automaton next generation. The behavior when the whole
11709 frame is filled is defined by the @option{scroll} option.
11711 This source accepts the following options:
11715 Read the initial cellular automaton state, i.e. the starting row, from
11716 the specified file.
11717 In the file, each non-whitespace character is considered an alive
11718 cell, a newline will terminate the row, and further characters in the
11719 file will be ignored.
11722 Read the initial cellular automaton state, i.e. the starting row, from
11723 the specified string.
11725 Each non-whitespace character in the string is considered an alive
11726 cell, a newline will terminate the row, and further characters in the
11727 string will be ignored.
11730 Set the video rate, that is the number of frames generated per second.
11733 @item random_fill_ratio, ratio
11734 Set the random fill ratio for the initial cellular automaton row. It
11735 is a floating point number value ranging from 0 to 1, defaults to
11738 This option is ignored when a file or a pattern is specified.
11740 @item random_seed, seed
11741 Set the seed for filling randomly the initial row, must be an integer
11742 included between 0 and UINT32_MAX. If not specified, or if explicitly
11743 set to -1, the filter will try to use a good random seed on a best
11747 Set the cellular automaton rule, it is a number ranging from 0 to 255.
11748 Default value is 110.
11751 Set the size of the output video. For the syntax of this option, check the
11752 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11754 If @option{filename} or @option{pattern} is specified, the size is set
11755 by default to the width of the specified initial state row, and the
11756 height is set to @var{width} * PHI.
11758 If @option{size} is set, it must contain the width of the specified
11759 pattern string, and the specified pattern will be centered in the
11762 If a filename or a pattern string is not specified, the size value
11763 defaults to "320x518" (used for a randomly generated initial state).
11766 If set to 1, scroll the output upward when all the rows in the output
11767 have been already filled. If set to 0, the new generated row will be
11768 written over the top row just after the bottom row is filled.
11771 @item start_full, full
11772 If set to 1, completely fill the output with generated rows before
11773 outputting the first frame.
11774 This is the default behavior, for disabling set the value to 0.
11777 If set to 1, stitch the left and right row edges together.
11778 This is the default behavior, for disabling set the value to 0.
11781 @subsection Examples
11785 Read the initial state from @file{pattern}, and specify an output of
11788 cellauto=f=pattern:s=200x400
11792 Generate a random initial row with a width of 200 cells, with a fill
11795 cellauto=ratio=2/3:s=200x200
11799 Create a pattern generated by rule 18 starting by a single alive cell
11800 centered on an initial row with width 100:
11802 cellauto=p=@@:s=100x400:full=0:rule=18
11806 Specify a more elaborated initial pattern:
11808 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
11813 @section mandelbrot
11815 Generate a Mandelbrot set fractal, and progressively zoom towards the
11816 point specified with @var{start_x} and @var{start_y}.
11818 This source accepts the following options:
11823 Set the terminal pts value. Default value is 400.
11826 Set the terminal scale value.
11827 Must be a floating point value. Default value is 0.3.
11830 Set the inner coloring mode, that is the algorithm used to draw the
11831 Mandelbrot fractal internal region.
11833 It shall assume one of the following values:
11838 Show time until convergence.
11840 Set color based on point closest to the origin of the iterations.
11845 Default value is @var{mincol}.
11848 Set the bailout value. Default value is 10.0.
11851 Set the maximum of iterations performed by the rendering
11852 algorithm. Default value is 7189.
11855 Set outer coloring mode.
11856 It shall assume one of following values:
11858 @item iteration_count
11859 Set iteration cound mode.
11860 @item normalized_iteration_count
11861 set normalized iteration count mode.
11863 Default value is @var{normalized_iteration_count}.
11866 Set frame rate, expressed as number of frames per second. Default
11870 Set frame size. For the syntax of this option, check the "Video
11871 size" section in the ffmpeg-utils manual. Default value is "640x480".
11874 Set the initial scale value. Default value is 3.0.
11877 Set the initial x position. Must be a floating point value between
11878 -100 and 100. Default value is -0.743643887037158704752191506114774.
11881 Set the initial y position. Must be a floating point value between
11882 -100 and 100. Default value is -0.131825904205311970493132056385139.
11887 Generate various test patterns, as generated by the MPlayer test filter.
11889 The size of the generated video is fixed, and is 256x256.
11890 This source is useful in particular for testing encoding features.
11892 This source accepts the following options:
11897 Specify the frame rate of the sourced video, as the number of frames
11898 generated per second. It has to be a string in the format
11899 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
11900 number or a valid video frame rate abbreviation. The default value is
11904 Set the duration of the sourced video. See
11905 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
11906 for the accepted syntax.
11908 If not specified, or the expressed duration is negative, the video is
11909 supposed to be generated forever.
11913 Set the number or the name of the test to perform. Supported tests are:
11929 Default value is "all", which will cycle through the list of all tests.
11934 mptestsrc=t=dc_luma
11937 will generate a "dc_luma" test pattern.
11939 @section frei0r_src
11941 Provide a frei0r source.
11943 To enable compilation of this filter you need to install the frei0r
11944 header and configure FFmpeg with @code{--enable-frei0r}.
11946 This source accepts the following parameters:
11951 The size of the video to generate. For the syntax of this option, check the
11952 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
11955 The framerate of the generated video. It may be a string of the form
11956 @var{num}/@var{den} or a frame rate abbreviation.
11959 The name to the frei0r source to load. For more information regarding frei0r and
11960 how to set the parameters, read the @ref{frei0r} section in the video filters
11963 @item filter_params
11964 A '|'-separated list of parameters to pass to the frei0r source.
11968 For example, to generate a frei0r partik0l source with size 200x200
11969 and frame rate 10 which is overlaid on the overlay filter main input:
11971 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
11976 Generate a life pattern.
11978 This source is based on a generalization of John Conway's life game.
11980 The sourced input represents a life grid, each pixel represents a cell
11981 which can be in one of two possible states, alive or dead. Every cell
11982 interacts with its eight neighbours, which are the cells that are
11983 horizontally, vertically, or diagonally adjacent.
11985 At each interaction the grid evolves according to the adopted rule,
11986 which specifies the number of neighbor alive cells which will make a
11987 cell stay alive or born. The @option{rule} option allows one to specify
11990 This source accepts the following options:
11994 Set the file from which to read the initial grid state. In the file,
11995 each non-whitespace character is considered an alive cell, and newline
11996 is used to delimit the end of each row.
11998 If this option is not specified, the initial grid is generated
12002 Set the video rate, that is the number of frames generated per second.
12005 @item random_fill_ratio, ratio
12006 Set the random fill ratio for the initial random grid. It is a
12007 floating point number value ranging from 0 to 1, defaults to 1/PHI.
12008 It is ignored when a file is specified.
12010 @item random_seed, seed
12011 Set the seed for filling the initial random grid, must be an integer
12012 included between 0 and UINT32_MAX. If not specified, or if explicitly
12013 set to -1, the filter will try to use a good random seed on a best
12019 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
12020 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
12021 @var{NS} specifies the number of alive neighbor cells which make a
12022 live cell stay alive, and @var{NB} the number of alive neighbor cells
12023 which make a dead cell to become alive (i.e. to "born").
12024 "s" and "b" can be used in place of "S" and "B", respectively.
12026 Alternatively a rule can be specified by an 18-bits integer. The 9
12027 high order bits are used to encode the next cell state if it is alive
12028 for each number of neighbor alive cells, the low order bits specify
12029 the rule for "borning" new cells. Higher order bits encode for an
12030 higher number of neighbor cells.
12031 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
12032 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
12034 Default value is "S23/B3", which is the original Conway's game of life
12035 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
12036 cells, and will born a new cell if there are three alive cells around
12040 Set the size of the output video. For the syntax of this option, check the
12041 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12043 If @option{filename} is specified, the size is set by default to the
12044 same size of the input file. If @option{size} is set, it must contain
12045 the size specified in the input file, and the initial grid defined in
12046 that file is centered in the larger resulting area.
12048 If a filename is not specified, the size value defaults to "320x240"
12049 (used for a randomly generated initial grid).
12052 If set to 1, stitch the left and right grid edges together, and the
12053 top and bottom edges also. Defaults to 1.
12056 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
12057 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
12058 value from 0 to 255.
12061 Set the color of living (or new born) cells.
12064 Set the color of dead cells. If @option{mold} is set, this is the first color
12065 used to represent a dead cell.
12068 Set mold color, for definitely dead and moldy cells.
12070 For the syntax of these 3 color options, check the "Color" section in the
12071 ffmpeg-utils manual.
12074 @subsection Examples
12078 Read a grid from @file{pattern}, and center it on a grid of size
12081 life=f=pattern:s=300x300
12085 Generate a random grid of size 200x200, with a fill ratio of 2/3:
12087 life=ratio=2/3:s=200x200
12091 Specify a custom rule for evolving a randomly generated grid:
12097 Full example with slow death effect (mold) using @command{ffplay}:
12099 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
12106 @anchor{haldclutsrc}
12108 @anchor{rgbtestsrc}
12110 @anchor{smptehdbars}
12112 @section allrgb, allyuv, color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
12114 The @code{allrgb} source returns frames of size 4096x4096 of all rgb colors.
12116 The @code{allyuv} source returns frames of size 4096x4096 of all yuv colors.
12118 The @code{color} source provides an uniformly colored input.
12120 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
12121 @ref{haldclut} filter.
12123 The @code{nullsrc} source returns unprocessed video frames. It is
12124 mainly useful to be employed in analysis / debugging tools, or as the
12125 source for filters which ignore the input data.
12127 The @code{rgbtestsrc} source generates an RGB test pattern useful for
12128 detecting RGB vs BGR issues. You should see a red, green and blue
12129 stripe from top to bottom.
12131 The @code{smptebars} source generates a color bars pattern, based on
12132 the SMPTE Engineering Guideline EG 1-1990.
12134 The @code{smptehdbars} source generates a color bars pattern, based on
12135 the SMPTE RP 219-2002.
12137 The @code{testsrc} source generates a test video pattern, showing a
12138 color pattern, a scrolling gradient and a timestamp. This is mainly
12139 intended for testing purposes.
12141 The sources accept the following parameters:
12146 Specify the color of the source, only available in the @code{color}
12147 source. For the syntax of this option, check the "Color" section in the
12148 ffmpeg-utils manual.
12151 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
12152 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
12153 pixels to be used as identity matrix for 3D lookup tables. Each component is
12154 coded on a @code{1/(N*N)} scale.
12157 Specify the size of the sourced video. For the syntax of this option, check the
12158 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12159 The default value is @code{320x240}.
12161 This option is not available with the @code{haldclutsrc} filter.
12164 Specify the frame rate of the sourced video, as the number of frames
12165 generated per second. It has to be a string in the format
12166 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
12167 number or a valid video frame rate abbreviation. The default value is
12171 Set the sample aspect ratio of the sourced video.
12174 Set the duration of the sourced video. See
12175 @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
12176 for the accepted syntax.
12178 If not specified, or the expressed duration is negative, the video is
12179 supposed to be generated forever.
12182 Set the number of decimals to show in the timestamp, only available in the
12183 @code{testsrc} source.
12185 The displayed timestamp value will correspond to the original
12186 timestamp value multiplied by the power of 10 of the specified
12187 value. Default value is 0.
12190 For example the following:
12192 testsrc=duration=5.3:size=qcif:rate=10
12195 will generate a video with a duration of 5.3 seconds, with size
12196 176x144 and a frame rate of 10 frames per second.
12198 The following graph description will generate a red source
12199 with an opacity of 0.2, with size "qcif" and a frame rate of 10
12202 color=c=red@@0.2:s=qcif:r=10
12205 If the input content is to be ignored, @code{nullsrc} can be used. The
12206 following command generates noise in the luminance plane by employing
12207 the @code{geq} filter:
12209 nullsrc=s=256x256, geq=random(1)*255:128:128
12212 @subsection Commands
12214 The @code{color} source supports the following commands:
12218 Set the color of the created image. Accepts the same syntax of the
12219 corresponding @option{color} option.
12222 @c man end VIDEO SOURCES
12224 @chapter Video Sinks
12225 @c man begin VIDEO SINKS
12227 Below is a description of the currently available video sinks.
12229 @section buffersink
12231 Buffer video frames, and make them available to the end of the filter
12234 This sink is mainly intended for programmatic use, in particular
12235 through the interface defined in @file{libavfilter/buffersink.h}
12236 or the options system.
12238 It accepts a pointer to an AVBufferSinkContext structure, which
12239 defines the incoming buffers' formats, to be passed as the opaque
12240 parameter to @code{avfilter_init_filter} for initialization.
12244 Null video sink: do absolutely nothing with the input video. It is
12245 mainly useful as a template and for use in analysis / debugging
12248 @c man end VIDEO SINKS
12250 @chapter Multimedia Filters
12251 @c man begin MULTIMEDIA FILTERS
12253 Below is a description of the currently available multimedia filters.
12255 @section aphasemeter
12257 Convert input audio to a video output, displaying the audio phase.
12259 The filter accepts the following options:
12263 Set the output frame rate. Default value is @code{25}.
12266 Set the video size for the output. For the syntax of this option, check the
12267 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12268 Default value is @code{800x400}.
12273 Specify the red, green, blue contrast. Default values are @code{2},
12274 @code{7} and @code{1}.
12275 Allowed range is @code{[0, 255]}.
12278 Set color which will be used for drawing median phase. If color is
12279 @code{none} which is default, no median phase value will be drawn.
12282 The filter also exports the frame metadata @code{lavfi.aphasemeter.phase} which
12283 represents mean phase of current audio frame. Value is in range @code{[-1, 1]}.
12284 The @code{-1} means left and right channels are completely out of phase and
12285 @code{1} means channels are in phase.
12287 @section avectorscope
12289 Convert input audio to a video output, representing the audio vector
12292 The filter is used to measure the difference between channels of stereo
12293 audio stream. A monoaural signal, consisting of identical left and right
12294 signal, results in straight vertical line. Any stereo separation is visible
12295 as a deviation from this line, creating a Lissajous figure.
12296 If the straight (or deviation from it) but horizontal line appears this
12297 indicates that the left and right channels are out of phase.
12299 The filter accepts the following options:
12303 Set the vectorscope mode.
12305 Available values are:
12308 Lissajous rotated by 45 degrees.
12311 Same as above but not rotated.
12314 Shape resembling half of circle.
12317 Default value is @samp{lissajous}.
12320 Set the video size for the output. For the syntax of this option, check the
12321 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12322 Default value is @code{400x400}.
12325 Set the output frame rate. Default value is @code{25}.
12331 Specify the red, green, blue and alpha contrast. Default values are @code{40},
12332 @code{160}, @code{80} and @code{255}.
12333 Allowed range is @code{[0, 255]}.
12339 Specify the red, green, blue and alpha fade. Default values are @code{15},
12340 @code{10}, @code{5} and @code{5}.
12341 Allowed range is @code{[0, 255]}.
12344 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
12347 @subsection Examples
12351 Complete example using @command{ffplay}:
12353 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
12354 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
12360 Concatenate audio and video streams, joining them together one after the
12363 The filter works on segments of synchronized video and audio streams. All
12364 segments must have the same number of streams of each type, and that will
12365 also be the number of streams at output.
12367 The filter accepts the following options:
12372 Set the number of segments. Default is 2.
12375 Set the number of output video streams, that is also the number of video
12376 streams in each segment. Default is 1.
12379 Set the number of output audio streams, that is also the number of audio
12380 streams in each segment. Default is 0.
12383 Activate unsafe mode: do not fail if segments have a different format.
12387 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
12388 @var{a} audio outputs.
12390 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
12391 segment, in the same order as the outputs, then the inputs for the second
12394 Related streams do not always have exactly the same duration, for various
12395 reasons including codec frame size or sloppy authoring. For that reason,
12396 related synchronized streams (e.g. a video and its audio track) should be
12397 concatenated at once. The concat filter will use the duration of the longest
12398 stream in each segment (except the last one), and if necessary pad shorter
12399 audio streams with silence.
12401 For this filter to work correctly, all segments must start at timestamp 0.
12403 All corresponding streams must have the same parameters in all segments; the
12404 filtering system will automatically select a common pixel format for video
12405 streams, and a common sample format, sample rate and channel layout for
12406 audio streams, but other settings, such as resolution, must be converted
12407 explicitly by the user.
12409 Different frame rates are acceptable but will result in variable frame rate
12410 at output; be sure to configure the output file to handle it.
12412 @subsection Examples
12416 Concatenate an opening, an episode and an ending, all in bilingual version
12417 (video in stream 0, audio in streams 1 and 2):
12419 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
12420 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
12421 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
12422 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
12426 Concatenate two parts, handling audio and video separately, using the
12427 (a)movie sources, and adjusting the resolution:
12429 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
12430 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
12431 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
12433 Note that a desync will happen at the stitch if the audio and video streams
12434 do not have exactly the same duration in the first file.
12441 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
12442 it unchanged. By default, it logs a message at a frequency of 10Hz with the
12443 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
12444 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
12446 The filter also has a video output (see the @var{video} option) with a real
12447 time graph to observe the loudness evolution. The graphic contains the logged
12448 message mentioned above, so it is not printed anymore when this option is set,
12449 unless the verbose logging is set. The main graphing area contains the
12450 short-term loudness (3 seconds of analysis), and the gauge on the right is for
12451 the momentary loudness (400 milliseconds).
12453 More information about the Loudness Recommendation EBU R128 on
12454 @url{http://tech.ebu.ch/loudness}.
12456 The filter accepts the following options:
12461 Activate the video output. The audio stream is passed unchanged whether this
12462 option is set or no. The video stream will be the first output stream if
12463 activated. Default is @code{0}.
12466 Set the video size. This option is for video only. For the syntax of this
12468 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
12469 Default and minimum resolution is @code{640x480}.
12472 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
12473 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
12474 other integer value between this range is allowed.
12477 Set metadata injection. If set to @code{1}, the audio input will be segmented
12478 into 100ms output frames, each of them containing various loudness information
12479 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
12481 Default is @code{0}.
12484 Force the frame logging level.
12486 Available values are:
12489 information logging level
12491 verbose logging level
12494 By default, the logging level is set to @var{info}. If the @option{video} or
12495 the @option{metadata} options are set, it switches to @var{verbose}.
12500 Available modes can be cumulated (the option is a @code{flag} type). Possible
12504 Disable any peak mode (default).
12506 Enable sample-peak mode.
12508 Simple peak mode looking for the higher sample value. It logs a message
12509 for sample-peak (identified by @code{SPK}).
12511 Enable true-peak mode.
12513 If enabled, the peak lookup is done on an over-sampled version of the input
12514 stream for better peak accuracy. It logs a message for true-peak.
12515 (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}).
12516 This mode requires a build with @code{libswresample}.
12521 @subsection Examples
12525 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
12527 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
12531 Run an analysis with @command{ffmpeg}:
12533 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
12537 @section interleave, ainterleave
12539 Temporally interleave frames from several inputs.
12541 @code{interleave} works with video inputs, @code{ainterleave} with audio.
12543 These filters read frames from several inputs and send the oldest
12544 queued frame to the output.
12546 Input streams must have a well defined, monotonically increasing frame
12549 In order to submit one frame to output, these filters need to enqueue
12550 at least one frame for each input, so they cannot work in case one
12551 input is not yet terminated and will not receive incoming frames.
12553 For example consider the case when one input is a @code{select} filter
12554 which always drop input frames. The @code{interleave} filter will keep
12555 reading from that input, but it will never be able to send new frames
12556 to output until the input will send an end-of-stream signal.
12558 Also, depending on inputs synchronization, the filters will drop
12559 frames in case one input receives more frames than the other ones, and
12560 the queue is already filled.
12562 These filters accept the following options:
12566 Set the number of different inputs, it is 2 by default.
12569 @subsection Examples
12573 Interleave frames belonging to different streams using @command{ffmpeg}:
12575 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
12579 Add flickering blur effect:
12581 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
12585 @section perms, aperms
12587 Set read/write permissions for the output frames.
12589 These filters are mainly aimed at developers to test direct path in the
12590 following filter in the filtergraph.
12592 The filters accept the following options:
12596 Select the permissions mode.
12598 It accepts the following values:
12601 Do nothing. This is the default.
12603 Set all the output frames read-only.
12605 Set all the output frames directly writable.
12607 Make the frame read-only if writable, and writable if read-only.
12609 Set each output frame read-only or writable randomly.
12613 Set the seed for the @var{random} mode, must be an integer included between
12614 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
12615 @code{-1}, the filter will try to use a good random seed on a best effort
12619 Note: in case of auto-inserted filter between the permission filter and the
12620 following one, the permission might not be received as expected in that
12621 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
12622 perms/aperms filter can avoid this problem.
12624 @section select, aselect
12626 Select frames to pass in output.
12628 This filter accepts the following options:
12633 Set expression, which is evaluated for each input frame.
12635 If the expression is evaluated to zero, the frame is discarded.
12637 If the evaluation result is negative or NaN, the frame is sent to the
12638 first output; otherwise it is sent to the output with index
12639 @code{ceil(val)-1}, assuming that the input index starts from 0.
12641 For example a value of @code{1.2} corresponds to the output with index
12642 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
12645 Set the number of outputs. The output to which to send the selected
12646 frame is based on the result of the evaluation. Default value is 1.
12649 The expression can contain the following constants:
12653 The (sequential) number of the filtered frame, starting from 0.
12656 The (sequential) number of the selected frame, starting from 0.
12658 @item prev_selected_n
12659 The sequential number of the last selected frame. It's NAN if undefined.
12662 The timebase of the input timestamps.
12665 The PTS (Presentation TimeStamp) of the filtered video frame,
12666 expressed in @var{TB} units. It's NAN if undefined.
12669 The PTS of the filtered video frame,
12670 expressed in seconds. It's NAN if undefined.
12673 The PTS of the previously filtered video frame. It's NAN if undefined.
12675 @item prev_selected_pts
12676 The PTS of the last previously filtered video frame. It's NAN if undefined.
12678 @item prev_selected_t
12679 The PTS of the last previously selected video frame. It's NAN if undefined.
12682 The PTS of the first video frame in the video. It's NAN if undefined.
12685 The time of the first video frame in the video. It's NAN if undefined.
12687 @item pict_type @emph{(video only)}
12688 The type of the filtered frame. It can assume one of the following
12700 @item interlace_type @emph{(video only)}
12701 The frame interlace type. It can assume one of the following values:
12704 The frame is progressive (not interlaced).
12706 The frame is top-field-first.
12708 The frame is bottom-field-first.
12711 @item consumed_sample_n @emph{(audio only)}
12712 the number of selected samples before the current frame
12714 @item samples_n @emph{(audio only)}
12715 the number of samples in the current frame
12717 @item sample_rate @emph{(audio only)}
12718 the input sample rate
12721 This is 1 if the filtered frame is a key-frame, 0 otherwise.
12724 the position in the file of the filtered frame, -1 if the information
12725 is not available (e.g. for synthetic video)
12727 @item scene @emph{(video only)}
12728 value between 0 and 1 to indicate a new scene; a low value reflects a low
12729 probability for the current frame to introduce a new scene, while a higher
12730 value means the current frame is more likely to be one (see the example below)
12734 The default value of the select expression is "1".
12736 @subsection Examples
12740 Select all frames in input:
12745 The example above is the same as:
12757 Select only I-frames:
12759 select='eq(pict_type\,I)'
12763 Select one frame every 100:
12765 select='not(mod(n\,100))'
12769 Select only frames contained in the 10-20 time interval:
12771 select=between(t\,10\,20)
12775 Select only I frames contained in the 10-20 time interval:
12777 select=between(t\,10\,20)*eq(pict_type\,I)
12781 Select frames with a minimum distance of 10 seconds:
12783 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
12787 Use aselect to select only audio frames with samples number > 100:
12789 aselect='gt(samples_n\,100)'
12793 Create a mosaic of the first scenes:
12795 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
12798 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
12802 Send even and odd frames to separate outputs, and compose them:
12804 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
12808 @section sendcmd, asendcmd
12810 Send commands to filters in the filtergraph.
12812 These filters read commands to be sent to other filters in the
12815 @code{sendcmd} must be inserted between two video filters,
12816 @code{asendcmd} must be inserted between two audio filters, but apart
12817 from that they act the same way.
12819 The specification of commands can be provided in the filter arguments
12820 with the @var{commands} option, or in a file specified by the
12821 @var{filename} option.
12823 These filters accept the following options:
12826 Set the commands to be read and sent to the other filters.
12828 Set the filename of the commands to be read and sent to the other
12832 @subsection Commands syntax
12834 A commands description consists of a sequence of interval
12835 specifications, comprising a list of commands to be executed when a
12836 particular event related to that interval occurs. The occurring event
12837 is typically the current frame time entering or leaving a given time
12840 An interval is specified by the following syntax:
12842 @var{START}[-@var{END}] @var{COMMANDS};
12845 The time interval is specified by the @var{START} and @var{END} times.
12846 @var{END} is optional and defaults to the maximum time.
12848 The current frame time is considered within the specified interval if
12849 it is included in the interval [@var{START}, @var{END}), that is when
12850 the time is greater or equal to @var{START} and is lesser than
12853 @var{COMMANDS} consists of a sequence of one or more command
12854 specifications, separated by ",", relating to that interval. The
12855 syntax of a command specification is given by:
12857 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
12860 @var{FLAGS} is optional and specifies the type of events relating to
12861 the time interval which enable sending the specified command, and must
12862 be a non-null sequence of identifier flags separated by "+" or "|" and
12863 enclosed between "[" and "]".
12865 The following flags are recognized:
12868 The command is sent when the current frame timestamp enters the
12869 specified interval. In other words, the command is sent when the
12870 previous frame timestamp was not in the given interval, and the
12874 The command is sent when the current frame timestamp leaves the
12875 specified interval. In other words, the command is sent when the
12876 previous frame timestamp was in the given interval, and the
12880 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
12883 @var{TARGET} specifies the target of the command, usually the name of
12884 the filter class or a specific filter instance name.
12886 @var{COMMAND} specifies the name of the command for the target filter.
12888 @var{ARG} is optional and specifies the optional list of argument for
12889 the given @var{COMMAND}.
12891 Between one interval specification and another, whitespaces, or
12892 sequences of characters starting with @code{#} until the end of line,
12893 are ignored and can be used to annotate comments.
12895 A simplified BNF description of the commands specification syntax
12898 @var{COMMAND_FLAG} ::= "enter" | "leave"
12899 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
12900 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
12901 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
12902 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
12903 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
12906 @subsection Examples
12910 Specify audio tempo change at second 4:
12912 asendcmd=c='4.0 atempo tempo 1.5',atempo
12916 Specify a list of drawtext and hue commands in a file.
12918 # show text in the interval 5-10
12919 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
12920 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
12922 # desaturate the image in the interval 15-20
12923 15.0-20.0 [enter] hue s 0,
12924 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
12926 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
12928 # apply an exponential saturation fade-out effect, starting from time 25
12929 25 [enter] hue s exp(25-t)
12932 A filtergraph allowing to read and process the above command list
12933 stored in a file @file{test.cmd}, can be specified with:
12935 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
12940 @section setpts, asetpts
12942 Change the PTS (presentation timestamp) of the input frames.
12944 @code{setpts} works on video frames, @code{asetpts} on audio frames.
12946 This filter accepts the following options:
12951 The expression which is evaluated for each frame to construct its timestamp.
12955 The expression is evaluated through the eval API and can contain the following
12960 frame rate, only defined for constant frame-rate video
12963 The presentation timestamp in input
12966 The count of the input frame for video or the number of consumed samples,
12967 not including the current frame for audio, starting from 0.
12969 @item NB_CONSUMED_SAMPLES
12970 The number of consumed samples, not including the current frame (only
12973 @item NB_SAMPLES, S
12974 The number of samples in the current frame (only audio)
12976 @item SAMPLE_RATE, SR
12977 The audio sample rate.
12980 The PTS of the first frame.
12983 the time in seconds of the first frame
12986 State whether the current frame is interlaced.
12989 the time in seconds of the current frame
12992 original position in the file of the frame, or undefined if undefined
12993 for the current frame
12996 The previous input PTS.
12999 previous input time in seconds
13002 The previous output PTS.
13005 previous output time in seconds
13008 The wallclock (RTC) time in microseconds. This is deprecated, use time(0)
13012 The wallclock (RTC) time at the start of the movie in microseconds.
13015 The timebase of the input timestamps.
13019 @subsection Examples
13023 Start counting PTS from zero
13025 setpts=PTS-STARTPTS
13029 Apply fast motion effect:
13035 Apply slow motion effect:
13041 Set fixed rate of 25 frames per second:
13047 Set fixed rate 25 fps with some jitter:
13049 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
13053 Apply an offset of 10 seconds to the input PTS:
13059 Generate timestamps from a "live source" and rebase onto the current timebase:
13061 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
13065 Generate timestamps by counting samples:
13072 @section settb, asettb
13074 Set the timebase to use for the output frames timestamps.
13075 It is mainly useful for testing timebase configuration.
13077 It accepts the following parameters:
13082 The expression which is evaluated into the output timebase.
13086 The value for @option{tb} is an arithmetic expression representing a
13087 rational. The expression can contain the constants "AVTB" (the default
13088 timebase), "intb" (the input timebase) and "sr" (the sample rate,
13089 audio only). Default value is "intb".
13091 @subsection Examples
13095 Set the timebase to 1/25:
13101 Set the timebase to 1/10:
13107 Set the timebase to 1001/1000:
13113 Set the timebase to 2*intb:
13119 Set the default timebase value:
13126 Convert input audio to a video output representing
13127 frequency spectrum logarithmically (using constant Q transform with
13128 Brown-Puckette algorithm), with musical tone scale, from E0 to D#10 (10 octaves).
13130 The filter accepts the following options:
13134 Specify transform volume (multiplier) expression. The expression can contain
13137 @item frequency, freq, f
13138 the frequency where transform is evaluated
13139 @item timeclamp, tc
13140 value of timeclamp option
13144 @item a_weighting(f)
13145 A-weighting of equal loudness
13146 @item b_weighting(f)
13147 B-weighting of equal loudness
13148 @item c_weighting(f)
13149 C-weighting of equal loudness
13151 Default value is @code{16}.
13154 Specify transform length expression. The expression can contain variables:
13156 @item frequency, freq, f
13157 the frequency where transform is evaluated
13158 @item timeclamp, tc
13159 value of timeclamp option
13161 Default value is @code{384/f*tc/(384/f+tc)}.
13164 Specify the transform timeclamp. At low frequency, there is trade-off between
13165 accuracy in time domain and frequency domain. If timeclamp is lower,
13166 event in time domain is represented more accurately (such as fast bass drum),
13167 otherwise event in frequency domain is represented more accurately
13168 (such as bass guitar). Acceptable value is [0.1, 1.0]. Default value is @code{0.17}.
13171 Specify the transform coeffclamp. If coeffclamp is lower, transform is
13172 more accurate, otherwise transform is faster. Acceptable value is [0.1, 10.0].
13173 Default value is @code{1.0}.
13176 Specify gamma. Lower gamma makes the spectrum more contrast, higher gamma
13177 makes the spectrum having more range. Acceptable value is [1.0, 7.0].
13178 Default value is @code{3.0}.
13181 Specify gamma of bargraph. Acceptable value is [1.0, 7.0].
13182 Default value is @code{1.0}.
13185 Specify font file for use with freetype. If not specified, use embedded font.
13188 Specify font color expression. This is arithmetic expression that should return
13189 integer value 0xRRGGBB. The expression can contain variables:
13191 @item frequency, freq, f
13192 the frequency where transform is evaluated
13193 @item timeclamp, tc
13194 value of timeclamp option
13199 midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
13200 @item r(x), g(x), b(x)
13201 red, green, and blue value of intensity x
13203 Default value is @code{st(0, (midi(f)-59.5)/12);
13204 st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));
13205 r(1-ld(1)) + b(ld(1))}
13208 If set to 1 (the default), the video size is 1920x1080 (full HD),
13209 if set to 0, the video size is 960x540. Use this option to make CPU usage lower.
13212 Specify video fps. Default value is @code{25}.
13215 Specify number of transform per frame, so there are fps*count transforms
13216 per second. Note that audio data rate must be divisible by fps*count.
13217 Default value is @code{6}.
13221 @subsection Examples
13225 Playing audio while showing the spectrum:
13227 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
13231 Same as above, but with frame rate 30 fps:
13233 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
13237 Playing at 960x540 and lower CPU usage:
13239 ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fullhd=0:count=3 [out0]'
13243 A1 and its harmonics: A1, A2, (near)E3, A3:
13245 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),
13246 asplit[a][out1]; [a] showcqt [out0]'
13250 Same as above, but with more accuracy in frequency domain (and slower):
13252 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),
13253 asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
13257 B-weighting of equal loudness
13259 volume=16*b_weighting(f)
13265 tlength=100/f*tc/(100/f+tc)
13269 Custom fontcolor, C-note is colored green, others are colored blue
13271 fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))'
13275 Custom gamma, now spectrum is linear to the amplitude.
13284 Convert input audio to video output representing the audio power spectrum.
13285 Audio amplitude is on Y-axis while frequency is on X-axis.
13287 The filter accepts the following options:
13291 Specify size of video. For the syntax of this option, check the
13292 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13293 Default is @code{1024x512}.
13297 This set how each frequency bin will be represented.
13299 It accepts the following values:
13305 Default is @code{bar}.
13308 Set amplitude scale.
13310 It accepts the following values:
13324 Default is @code{log}.
13327 Set frequency scale.
13329 It accepts the following values:
13338 Reverse logarithmic scale.
13340 Default is @code{lin}.
13345 It accepts the following values:
13361 Default is @code{w2048}
13364 Set windowing function.
13366 It accepts the following values:
13383 Default is @code{hanning}.
13386 Set window overlap. In range @code{[0, 1]}. Default is @code{1},
13387 which means optimal overlap for selected window function will be picked.
13390 Set time averaging. Setting this to 0 will display current maximal peaks.
13391 Default is @code{1}, which means time averaging is disabled.
13394 Specify list of colors separated by space or by '|' which will be used to
13395 draw channel frequencies. Unrecognized or missing colors will be replaced
13399 @section showspectrum
13401 Convert input audio to a video output, representing the audio frequency
13404 The filter accepts the following options:
13408 Specify the video size for the output. For the syntax of this option, check the
13409 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13410 Default value is @code{640x512}.
13413 Specify how the spectrum should slide along the window.
13415 It accepts the following values:
13418 the samples start again on the left when they reach the right
13420 the samples scroll from right to left
13422 frames are only produced when the samples reach the right
13425 Default value is @code{replace}.
13428 Specify display mode.
13430 It accepts the following values:
13433 all channels are displayed in the same row
13435 all channels are displayed in separate rows
13438 Default value is @samp{combined}.
13441 Specify display color mode.
13443 It accepts the following values:
13446 each channel is displayed in a separate color
13448 each channel is is displayed using the same color scheme
13451 Default value is @samp{channel}.
13454 Specify scale used for calculating intensity color values.
13456 It accepts the following values:
13461 square root, default
13468 Default value is @samp{sqrt}.
13471 Set saturation modifier for displayed colors. Negative values provide
13472 alternative color scheme. @code{0} is no saturation at all.
13473 Saturation must be in [-10.0, 10.0] range.
13474 Default value is @code{1}.
13477 Set window function.
13479 It accepts the following values:
13482 No samples pre-processing (do not expect this to be faster)
13491 Default value is @code{hann}.
13494 The usage is very similar to the showwaves filter; see the examples in that
13497 @subsection Examples
13501 Large window with logarithmic color scaling:
13503 showspectrum=s=1280x480:scale=log
13507 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
13509 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
13510 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
13514 @section showvolume
13516 Convert input audio volume to a video output.
13518 The filter accepts the following options:
13525 Set border width, allowed range is [0, 5]. Default is 1.
13528 Set channel width, allowed range is [40, 1080]. Default is 400.
13531 Set channel height, allowed range is [1, 100]. Default is 20.
13534 Set fade, allowed range is [1, 255]. Default is 20.
13537 Set volume color expression.
13539 The expression can use the following variables:
13543 Current max volume of channel in dB.
13546 Current channel number, starting from 0.
13550 If set, displays channel names. Default is enabled.
13555 Convert input audio to a video output, representing the samples waves.
13557 The filter accepts the following options:
13561 Specify the video size for the output. For the syntax of this option, check the
13562 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13563 Default value is @code{600x240}.
13568 Available values are:
13571 Draw a point for each sample.
13574 Draw a vertical line for each sample.
13577 Draw a point for each sample and a line between them.
13580 Draw a centered vertical line for each sample.
13583 Default value is @code{point}.
13586 Set the number of samples which are printed on the same column. A
13587 larger value will decrease the frame rate. Must be a positive
13588 integer. This option can be set only if the value for @var{rate}
13589 is not explicitly specified.
13592 Set the (approximate) output frame rate. This is done by setting the
13593 option @var{n}. Default value is "25".
13595 @item split_channels
13596 Set if channels should be drawn separately or overlap. Default value is 0.
13600 @subsection Examples
13604 Output the input file audio and the corresponding video representation
13607 amovie=a.mp3,asplit[out0],showwaves[out1]
13611 Create a synthetic signal and show it with showwaves, forcing a
13612 frame rate of 30 frames per second:
13614 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
13618 @section showwavespic
13620 Convert input audio to a single video frame, representing the samples waves.
13622 The filter accepts the following options:
13626 Specify the video size for the output. For the syntax of this option, check the
13627 @ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
13628 Default value is @code{600x240}.
13630 @item split_channels
13631 Set if channels should be drawn separately or overlap. Default value is 0.
13634 @subsection Examples
13638 Extract a channel split representation of the wave form of a whole audio track
13639 in a 1024x800 picture using @command{ffmpeg}:
13641 ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
13645 @section split, asplit
13647 Split input into several identical outputs.
13649 @code{asplit} works with audio input, @code{split} with video.
13651 The filter accepts a single parameter which specifies the number of outputs. If
13652 unspecified, it defaults to 2.
13654 @subsection Examples
13658 Create two separate outputs from the same input:
13660 [in] split [out0][out1]
13664 To create 3 or more outputs, you need to specify the number of
13667 [in] asplit=3 [out0][out1][out2]
13671 Create two separate outputs from the same input, one cropped and
13674 [in] split [splitout1][splitout2];
13675 [splitout1] crop=100:100:0:0 [cropout];
13676 [splitout2] pad=200:200:100:100 [padout];
13680 Create 5 copies of the input audio with @command{ffmpeg}:
13682 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
13688 Receive commands sent through a libzmq client, and forward them to
13689 filters in the filtergraph.
13691 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
13692 must be inserted between two video filters, @code{azmq} between two
13695 To enable these filters you need to install the libzmq library and
13696 headers and configure FFmpeg with @code{--enable-libzmq}.
13698 For more information about libzmq see:
13699 @url{http://www.zeromq.org/}
13701 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
13702 receives messages sent through a network interface defined by the
13703 @option{bind_address} option.
13705 The received message must be in the form:
13707 @var{TARGET} @var{COMMAND} [@var{ARG}]
13710 @var{TARGET} specifies the target of the command, usually the name of
13711 the filter class or a specific filter instance name.
13713 @var{COMMAND} specifies the name of the command for the target filter.
13715 @var{ARG} is optional and specifies the optional argument list for the
13716 given @var{COMMAND}.
13718 Upon reception, the message is processed and the corresponding command
13719 is injected into the filtergraph. Depending on the result, the filter
13720 will send a reply to the client, adopting the format:
13722 @var{ERROR_CODE} @var{ERROR_REASON}
13726 @var{MESSAGE} is optional.
13728 @subsection Examples
13730 Look at @file{tools/zmqsend} for an example of a zmq client which can
13731 be used to send commands processed by these filters.
13733 Consider the following filtergraph generated by @command{ffplay}
13735 ffplay -dumpgraph 1 -f lavfi "
13736 color=s=100x100:c=red [l];
13737 color=s=100x100:c=blue [r];
13738 nullsrc=s=200x100, zmq [bg];
13739 [bg][l] overlay [bg+l];
13740 [bg+l][r] overlay=x=100 "
13743 To change the color of the left side of the video, the following
13744 command can be used:
13746 echo Parsed_color_0 c yellow | tools/zmqsend
13749 To change the right side:
13751 echo Parsed_color_1 c pink | tools/zmqsend
13754 @c man end MULTIMEDIA FILTERS
13756 @chapter Multimedia Sources
13757 @c man begin MULTIMEDIA SOURCES
13759 Below is a description of the currently available multimedia sources.
13763 This is the same as @ref{movie} source, except it selects an audio
13769 Read audio and/or video stream(s) from a movie container.
13771 It accepts the following parameters:
13775 The name of the resource to read (not necessarily a file; it can also be a
13776 device or a stream accessed through some protocol).
13778 @item format_name, f
13779 Specifies the format assumed for the movie to read, and can be either
13780 the name of a container or an input device. If not specified, the
13781 format is guessed from @var{movie_name} or by probing.
13783 @item seek_point, sp
13784 Specifies the seek point in seconds. The frames will be output
13785 starting from this seek point. The parameter is evaluated with
13786 @code{av_strtod}, so the numerical value may be suffixed by an IS
13787 postfix. The default value is "0".
13790 Specifies the streams to read. Several streams can be specified,
13791 separated by "+". The source will then have as many outputs, in the
13792 same order. The syntax is explained in the ``Stream specifiers''
13793 section in the ffmpeg manual. Two special names, "dv" and "da" specify
13794 respectively the default (best suited) video and audio stream. Default
13795 is "dv", or "da" if the filter is called as "amovie".
13797 @item stream_index, si
13798 Specifies the index of the video stream to read. If the value is -1,
13799 the most suitable video stream will be automatically selected. The default
13800 value is "-1". Deprecated. If the filter is called "amovie", it will select
13801 audio instead of video.
13804 Specifies how many times to read the stream in sequence.
13805 If the value is less than 1, the stream will be read again and again.
13806 Default value is "1".
13808 Note that when the movie is looped the source timestamps are not
13809 changed, so it will generate non monotonically increasing timestamps.
13812 It allows overlaying a second video on top of the main input of
13813 a filtergraph, as shown in this graph:
13815 input -----------> deltapts0 --> overlay --> output
13818 movie --> scale--> deltapts1 -------+
13820 @subsection Examples
13824 Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
13825 on top of the input labelled "in":
13827 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
13828 [in] setpts=PTS-STARTPTS [main];
13829 [main][over] overlay=16:16 [out]
13833 Read from a video4linux2 device, and overlay it on top of the input
13836 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
13837 [in] setpts=PTS-STARTPTS [main];
13838 [main][over] overlay=16:16 [out]
13842 Read the first video stream and the audio stream with id 0x81 from
13843 dvd.vob; the video is connected to the pad named "video" and the audio is
13844 connected to the pad named "audio":
13846 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
13850 @c man end MULTIMEDIA SOURCES