1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
13 input --> split ---------------------> overlay --> output
16 +-----> crop --> vflip -------+
19 This filtergraph splits the input stream in two streams, sends one
20 stream through the crop filter and the vflip filter before merging it
21 back with the other stream by overlaying it on top. You can use the
22 following command to achieve this:
25 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
28 The result will be that in output the top half of the video is mirrored
31 Filters in the same linear chain are separated by commas, and distinct
32 linear chains of filters are separated by semicolons. In our example,
33 @var{crop,vflip} are in one linear chain, @var{split} and
34 @var{overlay} are separately in another. The points where the linear
35 chains join are labelled by names enclosed in square brackets. In the
36 example, the split filter generates two outputs that are associated to
37 the labels @var{[main]} and @var{[tmp]}.
39 The stream sent to the second output of @var{split}, labelled as
40 @var{[tmp]}, is processed through the @var{crop} filter, which crops
41 away the lower half part of the video, and then vertically flipped. The
42 @var{overlay} filter takes in input the first unchanged output of the
43 split filter (which was labelled as @var{[main]}), and overlay on its
44 lower half the output generated by the @var{crop,vflip} filterchain.
46 Some filters take in input a list of parameters: they are specified
47 after the filter name and an equal sign, and are separated from each other
50 There exist so-called @var{source filters} that do not have an
51 audio/video input, and @var{sink filters} that will not have audio/video
54 @c man end FILTERING INTRODUCTION
57 @c man begin GRAPH2DOT
59 The @file{graph2dot} program included in the FFmpeg @file{tools}
60 directory can be used to parse a filtergraph description and issue a
61 corresponding textual representation in the dot language.
68 to see how to use @file{graph2dot}.
70 You can then pass the dot description to the @file{dot} program (from
71 the graphviz suite of programs) and obtain a graphical representation
74 For example the sequence of commands:
76 echo @var{GRAPH_DESCRIPTION} | \
77 tools/graph2dot -o graph.tmp && \
78 dot -Tpng graph.tmp -o graph.png && \
82 can be used to create and display an image representing the graph
83 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
84 a complete self-contained graph, with its inputs and outputs explicitly defined.
85 For example if your command line is of the form:
87 ffmpeg -i infile -vf scale=640:360 outfile
89 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
91 nullsrc,scale=640:360,nullsink
93 you may also need to set the @var{nullsrc} parameters and add a @var{format}
94 filter in order to simulate a specific input file.
98 @chapter Filtergraph description
99 @c man begin FILTERGRAPH DESCRIPTION
101 A filtergraph is a directed graph of connected filters. It can contain
102 cycles, and there can be multiple links between a pair of
103 filters. Each link has one input pad on one side connecting it to one
104 filter from which it takes its input, and one output pad on the other
105 side connecting it to the one filter accepting its output.
107 Each filter in a filtergraph is an instance of a filter class
108 registered in the application, which defines the features and the
109 number of input and output pads of the filter.
111 A filter with no input pads is called a "source", a filter with no
112 output pads is called a "sink".
114 @anchor{Filtergraph syntax}
115 @section Filtergraph syntax
117 A filtergraph can be represented using a textual representation, which is
118 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
119 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
120 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
121 @file{libavfilter/avfilter.h}.
123 A filterchain consists of a sequence of connected filters, each one
124 connected to the previous one in the sequence. A filterchain is
125 represented by a list of ","-separated filter descriptions.
127 A filtergraph consists of a sequence of filterchains. A sequence of
128 filterchains is represented by a list of ";"-separated filterchain
131 A filter is represented by a string of the form:
132 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
134 @var{filter_name} is the name of the filter class of which the
135 described filter is an instance of, and has to be the name of one of
136 the filter classes registered in the program.
137 The name of the filter class is optionally followed by a string
140 @var{arguments} is a string which contains the parameters used to
141 initialize the filter instance. It may have one of the following forms:
145 A ':'-separated list of @var{key=value} pairs.
148 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
149 the option names in the order they are declared. E.g. the @code{fade} filter
150 declares three options in this order -- @option{type}, @option{start_frame} and
151 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
152 @var{in} is assigned to the option @option{type}, @var{0} to
153 @option{start_frame} and @var{30} to @option{nb_frames}.
156 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
157 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
158 follow the same constraints order of the previous point. The following
159 @var{key=value} pairs can be set in any preferred order.
163 If the option value itself is a list of items (e.g. the @code{format} filter
164 takes a list of pixel formats), the items in the list are usually separated by
167 The list of arguments can be quoted using the character "'" as initial
168 and ending mark, and the character '\' for escaping the characters
169 within the quoted text; otherwise the argument string is considered
170 terminated when the next special character (belonging to the set
171 "[]=;,") is encountered.
173 The name and arguments of the filter are optionally preceded and
174 followed by a list of link labels.
175 A link label allows to name a link and associate it to a filter output
176 or input pad. The preceding labels @var{in_link_1}
177 ... @var{in_link_N}, are associated to the filter input pads,
178 the following labels @var{out_link_1} ... @var{out_link_M}, are
179 associated to the output pads.
181 When two link labels with the same name are found in the
182 filtergraph, a link between the corresponding input and output pad is
185 If an output pad is not labelled, it is linked by default to the first
186 unlabelled input pad of the next filter in the filterchain.
187 For example in the filterchain:
189 nullsrc, split[L1], [L2]overlay, nullsink
191 the split filter instance has two output pads, and the overlay filter
192 instance two input pads. The first output pad of split is labelled
193 "L1", the first input pad of overlay is labelled "L2", and the second
194 output pad of split is linked to the second input pad of overlay,
195 which are both unlabelled.
197 In a complete filterchain all the unlabelled filter input and output
198 pads must be connected. A filtergraph is considered valid if all the
199 filter input and output pads of all the filterchains are connected.
201 Libavfilter will automatically insert scale filters where format
202 conversion is required. It is possible to specify swscale flags
203 for those automatically inserted scalers by prepending
204 @code{sws_flags=@var{flags};}
205 to the filtergraph description.
207 Follows a BNF description for the filtergraph syntax:
209 @var{NAME} ::= sequence of alphanumeric characters and '_'
210 @var{LINKLABEL} ::= "[" @var{NAME} "]"
211 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
212 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
213 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
214 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
215 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
218 @section Notes on filtergraph escaping
220 Some filter arguments require the use of special characters, typically
221 @code{:} to separate key=value pairs in a named options list. In this
222 case the user should perform a first level escaping when specifying
223 the filter arguments. For example, consider the following literal
224 string to be embedded in the @ref{drawtext} filter arguments:
226 this is a 'string': may contain one, or more, special characters
229 Since @code{:} is special for the filter arguments syntax, it needs to
230 be escaped, so you get:
232 text=this is a \'string\'\: may contain one, or more, special characters
235 A second level of escaping is required when embedding the filter
236 arguments in a filtergraph description, in order to escape all the
237 filtergraph special characters. Thus the example above becomes:
239 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
242 Finally an additional level of escaping may be needed when writing the
243 filtergraph description in a shell command, which depends on the
244 escaping rules of the adopted shell. For example, assuming that
245 @code{\} is special and needs to be escaped with another @code{\}, the
246 previous string will finally result in:
248 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
251 Sometimes, it might be more convenient to employ quoting in place of
252 escaping. For example the string:
254 Caesar: tu quoque, Brute, fili mi
257 Can be quoted in the filter arguments as:
259 text='Caesar: tu quoque, Brute, fili mi'
262 And finally inserted in a filtergraph like:
264 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
267 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
268 for more information about the escaping and quoting rules adopted by
271 @chapter Timeline editing
273 Some filters support a generic @option{enable} option. For the filters
274 supporting timeline editing, this option can be set to an expression which is
275 evaluated before sending a frame to the filter. If the evaluation is non-zero,
276 the filter will be enabled, otherwise the frame will be sent unchanged to the
277 next filter in the filtergraph.
279 The expression accepts the following values:
282 timestamp expressed in seconds, NAN if the input timestamp is unknown
285 sequential number of the input frame, starting from 0
288 the position in the file of the input frame, NAN if unknown
291 Additionally, these filters support an @option{enable} command that can be used
292 to re-define the expression.
294 Like any other filtering option, the @option{enable} option follows the same
297 For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3
298 minutes, and a @ref{curves} filter starting at 3 seconds:
300 smartblur = enable='between(t,10,3*60)',
301 curves = enable='gte(t,3)' : preset=cross_process
304 @c man end FILTERGRAPH DESCRIPTION
306 @chapter Audio Filters
307 @c man begin AUDIO FILTERS
309 When you configure your FFmpeg build, you can disable any of the
310 existing filters using @code{--disable-filters}.
311 The configure output will show the audio filters included in your
314 Below is a description of the currently available audio filters.
318 Convert the input audio format to the specified formats.
320 @emph{This filter is deprecated. Use @ref{aformat} instead.}
322 The filter accepts a string of the form:
323 "@var{sample_format}:@var{channel_layout}".
325 @var{sample_format} specifies the sample format, and can be a string or the
326 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
327 suffix for a planar sample format.
329 @var{channel_layout} specifies the channel layout, and can be a string
330 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
332 The special parameter "auto", signifies that the filter will
333 automatically select the output format depending on the output filter.
339 Convert input to float, planar, stereo:
345 Convert input to unsigned 8-bit, automatically select out channel layout:
353 Delay one or more audio channels.
355 Samples in delayed channel are filled with silence.
357 The filter accepts the following option:
361 Set list of delays in milliseconds for each channel separated by '|'.
362 At least one delay greater than 0 should be provided.
363 Unused delays will be silently ignored. If number of given delays is
364 smaller than number of channels all remaining channels will not be delayed.
371 Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
372 the second channel (and any other channels that may be present) unchanged.
380 Apply echoing to the input audio.
382 Echoes are reflected sound and can occur naturally amongst mountains
383 (and sometimes large buildings) when talking or shouting; digital echo
384 effects emulate this behaviour and are often used to help fill out the
385 sound of a single instrument or vocal. The time difference between the
386 original signal and the reflection is the @code{delay}, and the
387 loudness of the reflected signal is the @code{decay}.
388 Multiple echoes can have different delays and decays.
390 A description of the accepted parameters follows.
394 Set input gain of reflected signal. Default is @code{0.6}.
397 Set output gain of reflected signal. Default is @code{0.3}.
400 Set list of time intervals in milliseconds between original signal and reflections
401 separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}.
402 Default is @code{1000}.
405 Set list of loudnesses of reflected signals separated by '|'.
406 Allowed range for each @code{decay} is @code{(0 - 1.0]}.
407 Default is @code{0.5}.
414 Make it sound as if there are twice as many instruments as are actually playing:
416 aecho=0.8:0.88:60:0.4
420 If delay is very short, then it sound like a (metallic) robot playing music:
426 A longer delay will sound like an open air concert in the mountains:
428 aecho=0.8:0.9:1000:0.3
432 Same as above but with one more mountain:
434 aecho=0.8:0.9:1000|1800:0.3|0.25
440 Apply fade-in/out effect to input audio.
442 A description of the accepted parameters follows.
446 Specify the effect type, can be either @code{in} for fade-in, or
447 @code{out} for a fade-out effect. Default is @code{in}.
449 @item start_sample, ss
450 Specify the number of the start sample for starting to apply the fade
451 effect. Default is 0.
454 Specify the number of samples for which the fade effect has to last. At
455 the end of the fade-in effect the output audio will have the same
456 volume as the input audio, at the end of the fade-out transition
457 the output audio will be silence. Default is 44100.
460 Specify time for starting to apply the fade effect. Default is 0.
461 The accepted syntax is:
463 [-]HH[:MM[:SS[.m...]]]
466 See also the function @code{av_parse_time()}.
467 If set this option is used instead of @var{start_sample} one.
470 Specify the duration for which the fade effect has to last. Default is 0.
471 The accepted syntax is:
473 [-]HH[:MM[:SS[.m...]]]
476 See also the function @code{av_parse_time()}.
477 At the end of the fade-in effect the output audio will have the same
478 volume as the input audio, at the end of the fade-out transition
479 the output audio will be silence.
480 If set this option is used instead of @var{nb_samples} one.
483 Set curve for fade transition.
485 It accepts the following values:
488 select triangular, linear slope (default)
490 select quarter of sine wave
492 select half of sine wave
494 select exponential sine wave
498 select inverted parabola
514 Fade in first 15 seconds of audio:
520 Fade out last 25 seconds of a 900 seconds audio:
522 afade=t=out:st=875:d=25
529 Set output format constraints for the input audio. The framework will
530 negotiate the most appropriate format to minimize conversions.
532 The filter accepts the following named parameters:
536 A '|'-separated list of requested sample formats.
539 A '|'-separated list of requested sample rates.
541 @item channel_layouts
542 A '|'-separated list of requested channel layouts.
546 If a parameter is omitted, all values are allowed.
548 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
550 aformat=sample_fmts=u8|s16:channel_layouts=stereo
555 Apply a two-pole all-pass filter with central frequency (in Hz)
556 @var{frequency}, and filter-width @var{width}.
557 An all-pass filter changes the audio's frequency to phase relationship
558 without changing its frequency to amplitude relationship.
560 The filter accepts the following options:
567 Set method to specify band-width of filter.
580 Specify the band-width of a filter in width_type units.
585 Merge two or more audio streams into a single multi-channel stream.
587 The filter accepts the following options:
592 Set the number of inputs. Default is 2.
596 If the channel layouts of the inputs are disjoint, and therefore compatible,
597 the channel layout of the output will be set accordingly and the channels
598 will be reordered as necessary. If the channel layouts of the inputs are not
599 disjoint, the output will have all the channels of the first input then all
600 the channels of the second input, in that order, and the channel layout of
601 the output will be the default value corresponding to the total number of
604 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
605 is FC+BL+BR, then the output will be in 5.1, with the channels in the
606 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
607 first input, b1 is the first channel of the second input).
609 On the other hand, if both input are in stereo, the output channels will be
610 in the default order: a1, a2, b1, b2, and the channel layout will be
611 arbitrarily set to 4.0, which may or may not be the expected value.
613 All inputs must have the same sample rate, and format.
615 If inputs do not have the same duration, the output will stop with the
622 Merge two mono files into a stereo stream:
624 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
628 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
630 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
636 Mixes multiple audio inputs into a single output.
640 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
642 will mix 3 input audio streams to a single output with the same duration as the
643 first input and a dropout transition time of 3 seconds.
645 The filter accepts the following named parameters:
649 Number of inputs. If unspecified, it defaults to 2.
652 How to determine the end-of-stream.
656 Duration of longest input. (default)
659 Duration of shortest input.
662 Duration of first input.
666 @item dropout_transition
667 Transition time, in seconds, for volume renormalization when an input
668 stream ends. The default value is 2 seconds.
674 Pass the audio source unchanged to the output.
678 Pad the end of a audio stream with silence, this can be used together with
679 -shortest to extend audio streams to the same length as the video stream.
682 Add a phasing effect to the input audio.
684 A phaser filter creates series of peaks and troughs in the frequency spectrum.
685 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
687 A description of the accepted parameters follows.
691 Set input gain. Default is 0.4.
694 Set output gain. Default is 0.74
697 Set delay in milliseconds. Default is 3.0.
700 Set decay. Default is 0.4.
703 Set modulation speed in Hz. Default is 0.5.
706 Set modulation type. Default is triangular.
708 It accepts the following values:
718 Resample the input audio to the specified parameters, using the
719 libswresample library. If none are specified then the filter will
720 automatically convert between its input and output.
722 This filter is also able to stretch/squeeze the audio data to make it match
723 the timestamps or to inject silence / cut out audio to make it match the
724 timestamps, do a combination of both or do neither.
726 The filter accepts the syntax
727 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
728 expresses a sample rate and @var{resampler_options} is a list of
729 @var{key}=@var{value} pairs, separated by ":". See the
730 ffmpeg-resampler manual for the complete list of supported options.
736 Resample the input audio to 44100Hz:
742 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
743 samples per second compensation:
749 @section asetnsamples
751 Set the number of samples per each output audio frame.
753 The last output packet may contain a different number of samples, as
754 the filter will flush all the remaining samples when the input audio
757 The filter accepts the following options:
761 @item nb_out_samples, n
762 Set the number of frames per each output audio frame. The number is
763 intended as the number of samples @emph{per each channel}.
764 Default value is 1024.
767 If set to 1, the filter will pad the last audio frame with zeroes, so
768 that the last frame will contain the same number of samples as the
769 previous ones. Default value is 1.
772 For example, to set the number of per-frame samples to 1234 and
773 disable padding for the last frame, use:
775 asetnsamples=n=1234:p=0
780 Set the sample rate without altering the PCM data.
781 This will result in a change of speed and pitch.
783 The filter accepts the following options:
787 Set the output sample rate. Default is 44100 Hz.
792 Show a line containing various information for each input audio frame.
793 The input audio is not modified.
795 The shown line contains a sequence of key/value pairs of the form
796 @var{key}:@var{value}.
798 A description of each shown parameter follows:
802 sequential number of the input frame, starting from 0
805 Presentation timestamp of the input frame, in time base units; the time base
806 depends on the filter input pad, and is usually 1/@var{sample_rate}.
809 presentation timestamp of the input frame in seconds
812 position of the frame in the input stream, -1 if this information in
813 unavailable and/or meaningless (for example in case of synthetic audio)
822 sample rate for the audio frame
825 number of samples (per channel) in the frame
828 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
829 the data is treated as if all the planes were concatenated.
831 @item plane_checksums
832 A list of Adler-32 checksums for each data plane.
837 Display time domain statistical information about the audio channels.
838 Statistics are calculated and displayed for each audio channel and,
839 where applicable, an overall figure is also given.
841 The filter accepts the following option:
844 Short window length in seconds, used for peak and trough RMS measurement.
845 Default is @code{0.05} (50 miliseconds). Allowed range is @code{[0.1 - 10]}.
848 A description of each shown parameter follows:
852 Mean amplitude displacement from zero.
855 Minimal sample level.
858 Maximal sample level.
862 Standard peak and RMS level measured in dBFS.
866 Peak and trough values for RMS level measured over a short window.
869 Standard ratio of peak to RMS level (note: not in dB).
872 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
873 (i.e. either @var{Min level} or @var{Max level}).
876 Number of occasions (not the number of samples) that the signal attained either
877 @var{Min level} or @var{Max level}.
882 Forward two audio streams and control the order the buffers are forwarded.
884 The filter accepts the following options:
888 Set the expression deciding which stream should be
889 forwarded next: if the result is negative, the first stream is forwarded; if
890 the result is positive or zero, the second stream is forwarded. It can use
891 the following variables:
895 number of buffers forwarded so far on each stream
897 number of samples forwarded so far on each stream
899 current timestamp of each stream
902 The default value is @code{t1-t2}, which means to always forward the stream
903 that has a smaller timestamp.
908 Stress-test @code{amerge} by randomly sending buffers on the wrong
909 input, while avoiding too much of a desynchronization:
911 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
912 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
918 Synchronize audio data with timestamps by squeezing/stretching it and/or
919 dropping samples/adding silence when needed.
921 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
923 The filter accepts the following named parameters:
927 Enable stretching/squeezing the data to make it match the timestamps. Disabled
928 by default. When disabled, time gaps are covered with silence.
931 Minimum difference between timestamps and audio data (in seconds) to trigger
932 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
933 this filter, try setting this parameter to 0.
936 Maximum compensation in samples per second. Relevant only with compensate=1.
940 Assume the first pts should be this value. The time base is 1 / sample rate.
941 This allows for padding/trimming at the start of stream. By default, no
942 assumption is made about the first frame's expected pts, so no padding or
943 trimming is done. For example, this could be set to 0 to pad the beginning with
944 silence if an audio stream starts after the video stream or to trim any samples
945 with a negative pts due to encoder delay.
953 The filter accepts exactly one parameter, the audio tempo. If not
954 specified then the filter will assume nominal 1.0 tempo. Tempo must
955 be in the [0.5, 2.0] range.
961 Slow down audio to 80% tempo:
967 To speed up audio to 125% tempo:
975 Trim the input so that the output contains one continuous subpart of the input.
977 This filter accepts the following options:
980 Specify time of the start of the kept section, i.e. the audio sample
981 with the timestamp @var{start} will be the first sample in the output.
984 Specify time of the first audio sample that will be dropped, i.e. the
985 audio sample immediately preceding the one with the timestamp @var{end} will be
986 the last sample in the output.
989 Same as @var{start}, except this option sets the start timestamp in samples
993 Same as @var{end}, except this option sets the end timestamp in samples instead
997 Specify maximum duration of the output.
1000 Number of the first sample that should be passed to output.
1003 Number of the first sample that should be dropped.
1006 @option{start}, @option{end}, @option{duration} are expressed as time
1007 duration specifications, check the "Time duration" section in the
1008 ffmpeg-utils manual.
1010 Note that the first two sets of the start/end options and the @option{duration}
1011 option look at the frame timestamp, while the _sample options simply count the
1012 samples that pass through the filter. So start/end_pts and start/end_sample will
1013 give different results when the timestamps are wrong, inexact or do not start at
1014 zero. Also note that this filter does not modify the timestamps. If you wish
1015 that the output timestamps start at zero, insert the asetpts filter after the
1018 If multiple start or end options are set, this filter tries to be greedy and
1019 keep all samples that match at least one of the specified constraints. To keep
1020 only the part that matches all the constraints at once, chain multiple atrim
1023 The defaults are such that all the input is kept. So it is possible to set e.g.
1024 just the end values to keep everything before the specified time.
1029 drop everything except the second minute of input
1031 ffmpeg -i INPUT -af atrim=60:120
1035 keep only the first 1000 samples
1037 ffmpeg -i INPUT -af atrim=end_sample=1000
1044 Apply a two-pole Butterworth band-pass filter with central
1045 frequency @var{frequency}, and (3dB-point) band-width width.
1046 The @var{csg} option selects a constant skirt gain (peak gain = Q)
1047 instead of the default: constant 0dB peak gain.
1048 The filter roll off at 6dB per octave (20dB per decade).
1050 The filter accepts the following options:
1054 Set the filter's central frequency. Default is @code{3000}.
1057 Constant skirt gain if set to 1. Defaults to 0.
1060 Set method to specify band-width of filter.
1073 Specify the band-width of a filter in width_type units.
1078 Apply a two-pole Butterworth band-reject filter with central
1079 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
1080 The filter roll off at 6dB per octave (20dB per decade).
1082 The filter accepts the following options:
1086 Set the filter's central frequency. Default is @code{3000}.
1089 Set method to specify band-width of filter.
1102 Specify the band-width of a filter in width_type units.
1107 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1108 shelving filter with a response similar to that of a standard
1109 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1111 The filter accepts the following options:
1115 Give the gain at 0 Hz. Its useful range is about -20
1116 (for a large cut) to +20 (for a large boost).
1117 Beware of clipping when using a positive gain.
1120 Set the filter's central frequency and so can be used
1121 to extend or reduce the frequency range to be boosted or cut.
1122 The default value is @code{100} Hz.
1125 Set method to specify band-width of filter.
1138 Determine how steep is the filter's shelf transition.
1143 Apply a biquad IIR filter with the given coefficients.
1144 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1145 are the numerator and denominator coefficients respectively.
1149 Remap input channels to new locations.
1151 This filter accepts the following named parameters:
1153 @item channel_layout
1154 Channel layout of the output stream.
1157 Map channels from input to output. The argument is a '|'-separated list of
1158 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1159 @var{in_channel} form. @var{in_channel} can be either the name of the input
1160 channel (e.g. FL for front left) or its index in the input channel layout.
1161 @var{out_channel} is the name of the output channel or its index in the output
1162 channel layout. If @var{out_channel} is not given then it is implicitly an
1163 index, starting with zero and increasing by one for each mapping.
1166 If no mapping is present, the filter will implicitly map input channels to
1167 output channels preserving index.
1169 For example, assuming a 5.1+downmix input MOV file
1171 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1173 will create an output WAV file tagged as stereo from the downmix channels of
1176 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1178 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1181 @section channelsplit
1183 Split each channel in input audio stream into a separate output stream.
1185 This filter accepts the following named parameters:
1187 @item channel_layout
1188 Channel layout of the input stream. Default is "stereo".
1191 For example, assuming a stereo input MP3 file
1193 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1195 will create an output Matroska file with two audio streams, one containing only
1196 the left channel and the other the right channel.
1198 To split a 5.1 WAV file into per-channel files
1200 ffmpeg -i in.wav -filter_complex
1201 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1202 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1203 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1209 Compress or expand audio dynamic range.
1211 A description of the accepted options follows.
1216 Set list of times in seconds for each channel over which the instantaneous
1217 level of the input signal is averaged to determine its volume.
1218 @option{attacks} refers to increase of volume and @option{decays} refers
1219 to decrease of volume.
1220 For most situations, the attack time (response to the audio getting louder)
1221 should be shorter than the decay time because the human ear is more sensitive
1222 to sudden loud audio than sudden soft audio.
1223 Typical value for attack is @code{0.3} seconds and for decay @code{0.8}
1227 Set list of points for transfer function, specified in dB relative to maximum
1228 possible signal amplitude.
1229 Each key points list need to be defined using the following syntax:
1230 @code{x0/y0 x1/y1 x2/y2 ...}.
1232 The input values must be in strictly increasing order but the transfer
1233 function does not have to be monotonically rising.
1234 The point @code{0/0} is assumed but may be overridden (by @code{0/out-dBn}).
1235 Typical values for the transfer function are @code{-70/-70 -60/-20}.
1238 Set amount for which the points at where adjacent line segments on the
1239 transfer function meet will be rounded. Defaults is @code{0.01}.
1242 Set additional gain in dB to be applied at all points on the transfer function
1243 and allows easy adjustment of the overall gain.
1244 Default is @code{0}.
1247 Set initial volume in dB to be assumed for each channel when filtering starts.
1248 This permits the user to supply a nominal level initially, so that,
1249 for example, a very large gain is not applied to initial signal levels before
1250 the companding has begun to operate. A typical value for audio which is
1251 initially quiet is -90 dB. Default is @code{0}.
1254 Set delay in seconds. Default is @code{0}. The input audio
1255 is analysed immediately, but audio is delayed before being fed to the
1256 volume adjuster. Specifying a delay approximately equal to the attack/decay
1257 times allows the filter to effectively operate in predictive rather than
1261 @subsection Examples
1264 Make music with both quiet and loud passages suitable for listening
1265 in a noisy environment:
1267 compand=.3 .3:1 1:-90/-60 -60/-40 -40/-30 -20/-20:6:0:-90:0.2
1271 Noise-gate for when the noise is at a lower level than the signal:
1273 compand=.1 .1:.2 .2:-900/-900 -50.1/-900 -50/-50:.01:0:-90:.1
1277 Here is another noise-gate, this time for when the noise is at a higher level
1278 than the signal (making it, in some ways, similar to squelch):
1280 compand=.1 .1:.1 .1:-45.1/-45.1 -45/-900 0/-900:.01:45:-90:.1
1286 Make audio easier to listen to on headphones.
1288 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1289 so that when listened to on headphones the stereo image is moved from
1290 inside your head (standard for headphones) to outside and in front of
1291 the listener (standard for speakers).
1297 Apply a two-pole peaking equalisation (EQ) filter. With this
1298 filter, the signal-level at and around a selected frequency can
1299 be increased or decreased, whilst (unlike bandpass and bandreject
1300 filters) that at all other frequencies is unchanged.
1302 In order to produce complex equalisation curves, this filter can
1303 be given several times, each with a different central frequency.
1305 The filter accepts the following options:
1309 Set the filter's central frequency in Hz.
1312 Set method to specify band-width of filter.
1325 Specify the band-width of a filter in width_type units.
1328 Set the required gain or attenuation in dB.
1329 Beware of clipping when using a positive gain.
1334 Apply a high-pass filter with 3dB point frequency.
1335 The filter can be either single-pole, or double-pole (the default).
1336 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1338 The filter accepts the following options:
1342 Set frequency in Hz. Default is 3000.
1345 Set number of poles. Default is 2.
1348 Set method to specify band-width of filter.
1361 Specify the band-width of a filter in width_type units.
1362 Applies only to double-pole filter.
1363 The default is 0.707q and gives a Butterworth response.
1368 Join multiple input streams into one multi-channel stream.
1370 The filter accepts the following named parameters:
1374 Number of input streams. Defaults to 2.
1376 @item channel_layout
1377 Desired output channel layout. Defaults to stereo.
1380 Map channels from inputs to output. The argument is a '|'-separated list of
1381 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1382 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1383 can be either the name of the input channel (e.g. FL for front left) or its
1384 index in the specified input stream. @var{out_channel} is the name of the output
1388 The filter will attempt to guess the mappings when those are not specified
1389 explicitly. It does so by first trying to find an unused matching input channel
1390 and if that fails it picks the first unused input channel.
1392 E.g. to join 3 inputs (with properly set channel layouts)
1394 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1397 To build a 5.1 output from 6 single-channel streams:
1399 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1400 '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'
1406 Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
1408 To enable compilation of this filter you need to configure FFmpeg with
1409 @code{--enable-ladspa}.
1413 Specifies the name of LADSPA plugin library to load. If the environment
1414 variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in
1415 each one of the directories specified by the colon separated list in
1416 @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in
1417 this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/},
1418 @file{/usr/lib/ladspa/}.
1421 Specifies the plugin within the library. Some libraries contain only
1422 one plugin, but others contain many of them. If this is not set filter
1423 will list all available plugins within the specified library.
1426 Set the '|' separated list of controls which are zero or more floating point
1427 values that determine the behavior of the loaded plugin (for example delay,
1429 Controls need to be defined using the following syntax:
1430 c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where
1431 @var{valuei} is the value set on the @var{i}-th control.
1432 If @option{controls} is set to @code{help}, all available controls and
1433 their valid ranges are printed.
1435 @item sample_rate, s
1436 Specify the sample rate, default to 44100. Only used if plugin have
1440 Set the number of samples per channel per each output frame, default
1441 is 1024. Only used if plugin have zero inputs.
1444 Set the minimum duration of the sourced audio. See the function
1445 @code{av_parse_time()} for the accepted format, also check the "Time duration"
1446 section in the ffmpeg-utils manual.
1447 Note that the resulting duration may be greater than the specified duration,
1448 as the generated audio is always cut at the end of a complete frame.
1449 If not specified, or the expressed duration is negative, the audio is
1450 supposed to be generated forever.
1451 Only used if plugin have zero inputs.
1455 @subsection Examples
1459 List all available plugins within amp (LADSPA example plugin) library:
1465 List all available controls and their valid ranges for @code{vcf_notch}
1466 plugin from @code{VCF} library:
1468 ladspa=f=vcf:p=vcf_notch:c=help
1472 Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT)
1475 ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
1479 Add reverberation to the audio using TAP-plugins
1480 (Tom's Audio Processing plugins):
1482 ladspa=file=tap_reverb:tap_reverb
1486 Generate white noise, with 0.2 amplitude:
1488 ladspa=file=cmt:noise_source_white:c=c0=.2
1492 Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the
1493 @code{C* Audio Plugin Suite} (CAPS) library:
1495 ladspa=file=caps:Click:c=c1=20'
1499 Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect:
1501 ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
1507 Apply a low-pass filter with 3dB point frequency.
1508 The filter can be either single-pole or double-pole (the default).
1509 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1511 The filter accepts the following options:
1515 Set frequency in Hz. Default is 500.
1518 Set number of poles. Default is 2.
1521 Set method to specify band-width of filter.
1534 Specify the band-width of a filter in width_type units.
1535 Applies only to double-pole filter.
1536 The default is 0.707q and gives a Butterworth response.
1541 Mix channels with specific gain levels. The filter accepts the output
1542 channel layout followed by a set of channels definitions.
1544 This filter is also designed to remap efficiently the channels of an audio
1547 The filter accepts parameters of the form:
1548 "@var{l}:@var{outdef}:@var{outdef}:..."
1552 output channel layout or number of channels
1555 output channel specification, of the form:
1556 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1559 output channel to define, either a channel name (FL, FR, etc.) or a channel
1560 number (c0, c1, etc.)
1563 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1566 input channel to use, see out_name for details; it is not possible to mix
1567 named and numbered input channels
1570 If the `=' in a channel specification is replaced by `<', then the gains for
1571 that specification will be renormalized so that the total is 1, thus
1572 avoiding clipping noise.
1574 @subsection Mixing examples
1576 For example, if you want to down-mix from stereo to mono, but with a bigger
1577 factor for the left channel:
1579 pan=1:c0=0.9*c0+0.1*c1
1582 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1583 7-channels surround:
1585 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1588 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1589 that should be preferred (see "-ac" option) unless you have very specific
1592 @subsection Remapping examples
1594 The channel remapping will be effective if, and only if:
1597 @item gain coefficients are zeroes or ones,
1598 @item only one input per channel output,
1601 If all these conditions are satisfied, the filter will notify the user ("Pure
1602 channel mapping detected"), and use an optimized and lossless method to do the
1605 For example, if you have a 5.1 source and want a stereo audio stream by
1606 dropping the extra channels:
1608 pan="stereo: c0=FL : c1=FR"
1611 Given the same source, you can also switch front left and front right channels
1612 and keep the input channel layout:
1614 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1617 If the input is a stereo audio stream, you can mute the front left channel (and
1618 still keep the stereo channel layout) with:
1623 Still with a stereo audio stream input, you can copy the right channel in both
1624 front left and right:
1626 pan="stereo: c0=FR : c1=FR"
1631 Convert the audio sample format, sample rate and channel layout. This filter is
1632 not meant to be used directly.
1634 @section silencedetect
1636 Detect silence in an audio stream.
1638 This filter logs a message when it detects that the input audio volume is less
1639 or equal to a noise tolerance value for a duration greater or equal to the
1640 minimum detected noise duration.
1642 The printed times and duration are expressed in seconds.
1644 The filter accepts the following options:
1648 Set silence duration until notification (default is 2 seconds).
1651 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1652 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1655 @subsection Examples
1659 Detect 5 seconds of silence with -50dB noise tolerance:
1661 silencedetect=n=-50dB:d=5
1665 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1666 tolerance in @file{silence.mp3}:
1668 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
1674 Boost or cut treble (upper) frequencies of the audio using a two-pole
1675 shelving filter with a response similar to that of a standard
1676 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1678 The filter accepts the following options:
1682 Give the gain at whichever is the lower of ~22 kHz and the
1683 Nyquist frequency. Its useful range is about -20 (for a large cut)
1684 to +20 (for a large boost). Beware of clipping when using a positive gain.
1687 Set the filter's central frequency and so can be used
1688 to extend or reduce the frequency range to be boosted or cut.
1689 The default value is @code{3000} Hz.
1692 Set method to specify band-width of filter.
1705 Determine how steep is the filter's shelf transition.
1710 Adjust the input audio volume.
1712 The filter accepts the following options:
1717 Expresses how the audio volume will be increased or decreased.
1719 Output values are clipped to the maximum value.
1721 The output audio volume is given by the relation:
1723 @var{output_volume} = @var{volume} * @var{input_volume}
1726 Default value for @var{volume} is 1.0.
1729 Set the mathematical precision.
1731 This determines which input sample formats will be allowed, which affects the
1732 precision of the volume scaling.
1736 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1738 32-bit floating-point; limits input sample format to FLT. (default)
1740 64-bit floating-point; limits input sample format to DBL.
1744 @subsection Examples
1748 Halve the input audio volume:
1752 volume=volume=-6.0206dB
1755 In all the above example the named key for @option{volume} can be
1756 omitted, for example like in:
1762 Increase input audio power by 6 decibels using fixed-point precision:
1764 volume=volume=6dB:precision=fixed
1768 @section volumedetect
1770 Detect the volume of the input video.
1772 The filter has no parameters. The input is not modified. Statistics about
1773 the volume will be printed in the log when the input stream end is reached.
1775 In particular it will show the mean volume (root mean square), maximum
1776 volume (on a per-sample basis), and the beginning of a histogram of the
1777 registered volume values (from the maximum value to a cumulated 1/1000 of
1780 All volumes are in decibels relative to the maximum PCM value.
1782 @subsection Examples
1784 Here is an excerpt of the output:
1786 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1787 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1788 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1789 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1790 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1791 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1792 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1793 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1794 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1800 The mean square energy is approximately -27 dB, or 10^-2.7.
1802 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1804 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1807 In other words, raising the volume by +4 dB does not cause any clipping,
1808 raising it by +5 dB causes clipping for 6 samples, etc.
1810 @c man end AUDIO FILTERS
1812 @chapter Audio Sources
1813 @c man begin AUDIO SOURCES
1815 Below is a description of the currently available audio sources.
1819 Buffer audio frames, and make them available to the filter chain.
1821 This source is mainly intended for a programmatic use, in particular
1822 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1824 It accepts the following named parameters:
1829 Timebase which will be used for timestamps of submitted frames. It must be
1830 either a floating-point number or in @var{numerator}/@var{denominator} form.
1833 The sample rate of the incoming audio buffers.
1836 The sample format of the incoming audio buffers.
1837 Either a sample format name or its corresponging integer representation from
1838 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1840 @item channel_layout
1841 The channel layout of the incoming audio buffers.
1842 Either a channel layout name from channel_layout_map in
1843 @file{libavutil/channel_layout.c} or its corresponding integer representation
1844 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1847 The number of channels of the incoming audio buffers.
1848 If both @var{channels} and @var{channel_layout} are specified, then they
1853 @subsection Examples
1856 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1859 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1860 Since the sample format with name "s16p" corresponds to the number
1861 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1864 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1869 Generate an audio signal specified by an expression.
1871 This source accepts in input one or more expressions (one for each
1872 channel), which are evaluated and used to generate a corresponding
1875 This source accepts the following options:
1879 Set the '|'-separated expressions list for each separate channel. In case the
1880 @option{channel_layout} option is not specified, the selected channel layout
1881 depends on the number of provided expressions.
1883 @item channel_layout, c
1884 Set the channel layout. The number of channels in the specified layout
1885 must be equal to the number of specified expressions.
1888 Set the minimum duration of the sourced audio. See the function
1889 @code{av_parse_time()} for the accepted format.
1890 Note that the resulting duration may be greater than the specified
1891 duration, as the generated audio is always cut at the end of a
1894 If not specified, or the expressed duration is negative, the audio is
1895 supposed to be generated forever.
1898 Set the number of samples per channel per each output frame,
1901 @item sample_rate, s
1902 Specify the sample rate, default to 44100.
1905 Each expression in @var{exprs} can contain the following constants:
1909 number of the evaluated sample, starting from 0
1912 time of the evaluated sample expressed in seconds, starting from 0
1919 @subsection Examples
1929 Generate a sin signal with frequency of 440 Hz, set sample rate to
1932 aevalsrc="sin(440*2*PI*t):s=8000"
1936 Generate a two channels signal, specify the channel layout (Front
1937 Center + Back Center) explicitly:
1939 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
1943 Generate white noise:
1945 aevalsrc="-2+random(0)"
1949 Generate an amplitude modulated signal:
1951 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1955 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1957 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
1964 Null audio source, return unprocessed audio frames. It is mainly useful
1965 as a template and to be employed in analysis / debugging tools, or as
1966 the source for filters which ignore the input data (for example the sox
1969 This source accepts the following options:
1973 @item channel_layout, cl
1975 Specify the channel layout, and can be either an integer or a string
1976 representing a channel layout. The default value of @var{channel_layout}
1979 Check the channel_layout_map definition in
1980 @file{libavutil/channel_layout.c} for the mapping between strings and
1981 channel layout values.
1983 @item sample_rate, r
1984 Specify the sample rate, and defaults to 44100.
1987 Set the number of samples per requested frames.
1991 @subsection Examples
1995 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1997 anullsrc=r=48000:cl=4
2001 Do the same operation with a more obvious syntax:
2003 anullsrc=r=48000:cl=mono
2007 All the parameters need to be explicitly defined.
2011 Synthesize a voice utterance using the libflite library.
2013 To enable compilation of this filter you need to configure FFmpeg with
2014 @code{--enable-libflite}.
2016 Note that the flite library is not thread-safe.
2018 The filter accepts the following options:
2023 If set to 1, list the names of the available voices and exit
2024 immediately. Default value is 0.
2027 Set the maximum number of samples per frame. Default value is 512.
2030 Set the filename containing the text to speak.
2033 Set the text to speak.
2036 Set the voice to use for the speech synthesis. Default value is
2037 @code{kal}. See also the @var{list_voices} option.
2040 @subsection Examples
2044 Read from file @file{speech.txt}, and synthetize the text using the
2045 standard flite voice:
2047 flite=textfile=speech.txt
2051 Read the specified text selecting the @code{slt} voice:
2053 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2057 Input text to ffmpeg:
2059 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
2063 Make @file{ffplay} speak the specified text, using @code{flite} and
2064 the @code{lavfi} device:
2066 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
2070 For more information about libflite, check:
2071 @url{http://www.speech.cs.cmu.edu/flite/}
2075 Generate an audio signal made of a sine wave with amplitude 1/8.
2077 The audio signal is bit-exact.
2079 The filter accepts the following options:
2084 Set the carrier frequency. Default is 440 Hz.
2086 @item beep_factor, b
2087 Enable a periodic beep every second with frequency @var{beep_factor} times
2088 the carrier frequency. Default is 0, meaning the beep is disabled.
2090 @item sample_rate, r
2091 Specify the sample rate, default is 44100.
2094 Specify the duration of the generated audio stream.
2096 @item samples_per_frame
2097 Set the number of samples per output frame, default is 1024.
2100 @subsection Examples
2105 Generate a simple 440 Hz sine wave:
2111 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
2115 sine=frequency=220:beep_factor=4:duration=5
2120 @c man end AUDIO SOURCES
2122 @chapter Audio Sinks
2123 @c man begin AUDIO SINKS
2125 Below is a description of the currently available audio sinks.
2127 @section abuffersink
2129 Buffer audio frames, and make them available to the end of filter chain.
2131 This sink is mainly intended for programmatic use, in particular
2132 through the interface defined in @file{libavfilter/buffersink.h}
2133 or the options system.
2135 It accepts a pointer to an AVABufferSinkContext structure, which
2136 defines the incoming buffers' formats, to be passed as the opaque
2137 parameter to @code{avfilter_init_filter} for initialization.
2141 Null audio sink, do absolutely nothing with the input audio. It is
2142 mainly useful as a template and to be employed in analysis / debugging
2145 @c man end AUDIO SINKS
2147 @chapter Video Filters
2148 @c man begin VIDEO FILTERS
2150 When you configure your FFmpeg build, you can disable any of the
2151 existing filters using @code{--disable-filters}.
2152 The configure output will show the video filters included in your
2155 Below is a description of the currently available video filters.
2157 @section alphaextract
2159 Extract the alpha component from the input as a grayscale video. This
2160 is especially useful with the @var{alphamerge} filter.
2164 Add or replace the alpha component of the primary input with the
2165 grayscale value of a second input. This is intended for use with
2166 @var{alphaextract} to allow the transmission or storage of frame
2167 sequences that have alpha in a format that doesn't support an alpha
2170 For example, to reconstruct full frames from a normal YUV-encoded video
2171 and a separate video created with @var{alphaextract}, you might use:
2173 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
2176 Since this filter is designed for reconstruction, it operates on frame
2177 sequences without considering timestamps, and terminates when either
2178 input reaches end of stream. This will cause problems if your encoding
2179 pipeline drops frames. If you're trying to apply an image as an
2180 overlay to a video stream, consider the @var{overlay} filter instead.
2184 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
2185 and libavformat to work. On the other hand, it is limited to ASS (Advanced
2186 Substation Alpha) subtitles files.
2190 Compute the bounding box for the non-black pixels in the input frame
2193 This filter computes the bounding box containing all the pixels with a
2194 luminance value greater than the minimum allowed value.
2195 The parameters describing the bounding box are printed on the filter
2198 The filter accepts the following option:
2202 Set the minimal luminance value. Default is @code{16}.
2205 @section blackdetect
2207 Detect video intervals that are (almost) completely black. Can be
2208 useful to detect chapter transitions, commercials, or invalid
2209 recordings. Output lines contains the time for the start, end and
2210 duration of the detected black interval expressed in seconds.
2212 In order to display the output lines, you need to set the loglevel at
2213 least to the AV_LOG_INFO value.
2215 The filter accepts the following options:
2218 @item black_min_duration, d
2219 Set the minimum detected black duration expressed in seconds. It must
2220 be a non-negative floating point number.
2222 Default value is 2.0.
2224 @item picture_black_ratio_th, pic_th
2225 Set the threshold for considering a picture "black".
2226 Express the minimum value for the ratio:
2228 @var{nb_black_pixels} / @var{nb_pixels}
2231 for which a picture is considered black.
2232 Default value is 0.98.
2234 @item pixel_black_th, pix_th
2235 Set the threshold for considering a pixel "black".
2237 The threshold expresses the maximum pixel luminance value for which a
2238 pixel is considered "black". The provided value is scaled according to
2239 the following equation:
2241 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
2244 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
2245 the input video format, the range is [0-255] for YUV full-range
2246 formats and [16-235] for YUV non full-range formats.
2248 Default value is 0.10.
2251 The following example sets the maximum pixel threshold to the minimum
2252 value, and detects only black intervals of 2 or more seconds:
2254 blackdetect=d=2:pix_th=0.00
2259 Detect frames that are (almost) completely black. Can be useful to
2260 detect chapter transitions or commercials. Output lines consist of
2261 the frame number of the detected frame, the percentage of blackness,
2262 the position in the file if known or -1 and the timestamp in seconds.
2264 In order to display the output lines, you need to set the loglevel at
2265 least to the AV_LOG_INFO value.
2267 The filter accepts the following options:
2272 Set the percentage of the pixels that have to be below the threshold, defaults
2275 @item threshold, thresh
2276 Set the threshold below which a pixel value is considered black, defaults to
2283 Blend two video frames into each other.
2285 It takes two input streams and outputs one stream, the first input is the
2286 "top" layer and second input is "bottom" layer.
2287 Output terminates when shortest input terminates.
2289 A description of the accepted options follows.
2297 Set blend mode for specific pixel component or all pixel components in case
2298 of @var{all_mode}. Default value is @code{normal}.
2300 Available values for component modes are:
2333 Set blend opacity for specific pixel component or all pixel components in case
2334 of @var{all_opacity}. Only used in combination with pixel component blend modes.
2341 Set blend expression for specific pixel component or all pixel components in case
2342 of @var{all_expr}. Note that related mode options will be ignored if those are set.
2344 The expressions can use the following variables:
2348 The sequential number of the filtered frame, starting from @code{0}.
2352 the coordinates of the current sample
2356 the width and height of currently filtered plane
2360 Width and height scale depending on the currently filtered plane. It is the
2361 ratio between the corresponding luma plane number of pixels and the current
2362 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2363 @code{0.5,0.5} for chroma planes.
2366 Time of the current frame, expressed in seconds.
2369 Value of pixel component at current location for first video frame (top layer).
2372 Value of pixel component at current location for second video frame (bottom layer).
2376 Force termination when the shortest input terminates. Default is @code{0}.
2378 Continue applying the last bottom frame after the end of the stream. A value of
2379 @code{0} disable the filter after the last frame of the bottom layer is reached.
2380 Default is @code{1}.
2383 @subsection Examples
2387 Apply transition from bottom layer to top layer in first 10 seconds:
2389 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2393 Apply 1x1 checkerboard effect:
2395 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2401 Apply boxblur algorithm to the input video.
2403 The filter accepts the following options:
2407 @item luma_radius, lr
2408 @item luma_power, lp
2409 @item chroma_radius, cr
2410 @item chroma_power, cp
2411 @item alpha_radius, ar
2412 @item alpha_power, ap
2416 A description of the accepted options follows.
2419 @item luma_radius, lr
2420 @item chroma_radius, cr
2421 @item alpha_radius, ar
2422 Set an expression for the box radius in pixels used for blurring the
2423 corresponding input plane.
2425 The radius value must be a non-negative number, and must not be
2426 greater than the value of the expression @code{min(w,h)/2} for the
2427 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2430 Default value for @option{luma_radius} is "2". If not specified,
2431 @option{chroma_radius} and @option{alpha_radius} default to the
2432 corresponding value set for @option{luma_radius}.
2434 The expressions can contain the following constants:
2438 the input width and height in pixels
2442 the input chroma image width and height in pixels
2446 horizontal and vertical chroma subsample values. For example for the
2447 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2450 @item luma_power, lp
2451 @item chroma_power, cp
2452 @item alpha_power, ap
2453 Specify how many times the boxblur filter is applied to the
2454 corresponding plane.
2456 Default value for @option{luma_power} is 2. If not specified,
2457 @option{chroma_power} and @option{alpha_power} default to the
2458 corresponding value set for @option{luma_power}.
2460 A value of 0 will disable the effect.
2463 @subsection Examples
2467 Apply a boxblur filter with luma, chroma, and alpha radius
2470 boxblur=luma_radius=2:luma_power=1
2475 Set luma radius to 2, alpha and chroma radius to 0:
2477 boxblur=2:1:cr=0:ar=0
2481 Set luma and chroma radius to a fraction of the video dimension:
2483 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2487 @section colorbalance
2488 Modify intensity of primary colors (red, green and blue) of input frames.
2490 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
2491 regions for the red-cyan, green-magenta or blue-yellow balance.
2493 A positive adjustment value shifts the balance towards the primary color, a negative
2494 value towards the complementary color.
2496 The filter accepts the following options:
2502 Adjust red, green and blue shadows (darkest pixels).
2507 Adjust red, green and blue midtones (medium pixels).
2512 Adjust red, green and blue highlights (brightest pixels).
2514 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
2517 @subsection Examples
2521 Add red color cast to shadows:
2527 @section colorchannelmixer
2529 Adjust video input frames by re-mixing color channels.
2531 This filter modifies a color channel by adding the values associated to
2532 the other channels of the same pixels. For example if the value to
2533 modify is red, the output value will be:
2535 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
2538 The filter accepts the following options:
2545 Adjust contribution of input red, green, blue and alpha channels for output red channel.
2546 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
2552 Adjust contribution of input red, green, blue and alpha channels for output green channel.
2553 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
2559 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
2560 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
2566 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
2567 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
2569 Allowed ranges for options are @code{[-2.0, 2.0]}.
2572 @subsection Examples
2576 Convert source to grayscale:
2578 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
2581 Simulate sepia tones:
2583 colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
2587 @section colormatrix
2589 Convert color matrix.
2591 The filter accepts the following options:
2596 Specify the source and destination color matrix. Both values must be
2599 The accepted values are:
2615 For example to convert from BT.601 to SMPTE-240M, use the command:
2617 colormatrix=bt601:smpte240m
2622 Copy the input source unchanged to the output. Mainly useful for
2627 Crop the input video to given dimensions.
2629 The filter accepts the following options:
2633 Width of the output video. It defaults to @code{iw}.
2634 This expression is evaluated only once during the filter
2638 Height of the output video. It defaults to @code{ih}.
2639 This expression is evaluated only once during the filter
2643 Horizontal position, in the input video, of the left edge of the output video.
2644 It defaults to @code{(in_w-out_w)/2}.
2645 This expression is evaluated per-frame.
2648 Vertical position, in the input video, of the top edge of the output video.
2649 It defaults to @code{(in_h-out_h)/2}.
2650 This expression is evaluated per-frame.
2653 If set to 1 will force the output display aspect ratio
2654 to be the same of the input, by changing the output sample aspect
2655 ratio. It defaults to 0.
2658 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2659 expressions containing the following constants:
2664 the computed values for @var{x} and @var{y}. They are evaluated for
2669 the input width and height
2673 same as @var{in_w} and @var{in_h}
2677 the output (cropped) width and height
2681 same as @var{out_w} and @var{out_h}
2684 same as @var{iw} / @var{ih}
2687 input sample aspect ratio
2690 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2694 horizontal and vertical chroma subsample values. For example for the
2695 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2698 the number of input frame, starting from 0
2701 the position in the file of the input frame, NAN if unknown
2704 timestamp expressed in seconds, NAN if the input timestamp is unknown
2708 The expression for @var{out_w} may depend on the value of @var{out_h},
2709 and the expression for @var{out_h} may depend on @var{out_w}, but they
2710 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2711 evaluated after @var{out_w} and @var{out_h}.
2713 The @var{x} and @var{y} parameters specify the expressions for the
2714 position of the top-left corner of the output (non-cropped) area. They
2715 are evaluated for each frame. If the evaluated value is not valid, it
2716 is approximated to the nearest valid value.
2718 The expression for @var{x} may depend on @var{y}, and the expression
2719 for @var{y} may depend on @var{x}.
2721 @subsection Examples
2725 Crop area with size 100x100 at position (12,34).
2730 Using named options, the example above becomes:
2732 crop=w=100:h=100:x=12:y=34
2736 Crop the central input area with size 100x100:
2742 Crop the central input area with size 2/3 of the input video:
2744 crop=2/3*in_w:2/3*in_h
2748 Crop the input video central square:
2755 Delimit the rectangle with the top-left corner placed at position
2756 100:100 and the right-bottom corner corresponding to the right-bottom
2757 corner of the input image:
2759 crop=in_w-100:in_h-100:100:100
2763 Crop 10 pixels from the left and right borders, and 20 pixels from
2764 the top and bottom borders
2766 crop=in_w-2*10:in_h-2*20
2770 Keep only the bottom right quarter of the input image:
2772 crop=in_w/2:in_h/2:in_w/2:in_h/2
2776 Crop height for getting Greek harmony:
2778 crop=in_w:1/PHI*in_w
2782 Appply trembling effect:
2784 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)
2788 Apply erratic camera effect depending on timestamp:
2790 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)"
2794 Set x depending on the value of y:
2796 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2802 Auto-detect crop size.
2804 Calculate necessary cropping parameters and prints the recommended
2805 parameters through the logging system. The detected dimensions
2806 correspond to the non-black area of the input video.
2808 The filter accepts the following options:
2813 Set higher black value threshold, which can be optionally specified
2814 from nothing (0) to everything (255). An intensity value greater
2815 to the set value is considered non-black. Default value is 24.
2818 Set the value for which the width/height should be divisible by. The
2819 offset is automatically adjusted to center the video. Use 2 to get
2820 only even dimensions (needed for 4:2:2 video). 16 is best when
2821 encoding to most video codecs. Default value is 16.
2823 @item reset_count, reset
2824 Set the counter that determines after how many frames cropdetect will
2825 reset the previously detected largest video area and start over to
2826 detect the current optimal crop area. Default value is 0.
2828 This can be useful when channel logos distort the video area. 0
2829 indicates never reset and return the largest area encountered during
2836 Apply color adjustments using curves.
2838 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2839 component (red, green and blue) has its values defined by @var{N} key points
2840 tied from each other using a smooth curve. The x-axis represents the pixel
2841 values from the input frame, and the y-axis the new pixel values to be set for
2844 By default, a component curve is defined by the two points @var{(0;0)} and
2845 @var{(1;1)}. This creates a straight line where each original pixel value is
2846 "adjusted" to its own value, which means no change to the image.
2848 The filter allows you to redefine these two points and add some more. A new
2849 curve (using a natural cubic spline interpolation) will be define to pass
2850 smoothly through all these new coordinates. The new defined points needs to be
2851 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2852 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2853 the vector spaces, the values will be clipped accordingly.
2855 If there is no key point defined in @code{x=0}, the filter will automatically
2856 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2857 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2859 The filter accepts the following options:
2863 Select one of the available color presets. This option can be used in addition
2864 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2865 options takes priority on the preset values.
2866 Available presets are:
2869 @item color_negative
2872 @item increase_contrast
2874 @item linear_contrast
2875 @item medium_contrast
2877 @item strong_contrast
2880 Default is @code{none}.
2882 Set the master key points. These points will define a second pass mapping. It
2883 is sometimes called a "luminance" or "value" mapping. It can be used with
2884 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
2885 post-processing LUT.
2887 Set the key points for the red component.
2889 Set the key points for the green component.
2891 Set the key points for the blue component.
2893 Set the key points for all components (not including master).
2894 Can be used in addition to the other key points component
2895 options. In this case, the unset component(s) will fallback on this
2896 @option{all} setting.
2898 Specify a Photoshop curves file (@code{.asv}) to import the settings from.
2901 To avoid some filtergraph syntax conflicts, each key points list need to be
2902 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2904 @subsection Examples
2908 Increase slightly the middle level of blue:
2910 curves=blue='0.5/0.58'
2916 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2918 Here we obtain the following coordinates for each components:
2921 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2923 @code{(0;0) (0.50;0.48) (1;1)}
2925 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2929 The previous example can also be achieved with the associated built-in preset:
2931 curves=preset=vintage
2941 Use a Photoshop preset and redefine the points of the green component:
2943 curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53'
2949 Denoise frames using 2D DCT (frequency domain filtering).
2951 This filter is not designed for real time and can be extremely slow.
2953 The filter accepts the following options:
2957 Set the noise sigma constant.
2959 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
2960 coefficient (absolute value) below this threshold with be dropped.
2962 If you need a more advanced filtering, see @option{expr}.
2964 Default is @code{0}.
2967 Set number overlapping pixels for each block. Each block is of size
2968 @code{16x16}. Since the filter can be slow, you may want to reduce this value,
2969 at the cost of a less effective filter and the risk of various artefacts.
2971 If the overlapping value doesn't allow to process the whole input width or
2972 height, a warning will be displayed and according borders won't be denoised.
2974 Default value is @code{15}.
2977 Set the coefficient factor expression.
2979 For each coefficient of a DCT block, this expression will be evaluated as a
2980 multiplier value for the coefficient.
2982 If this is option is set, the @option{sigma} option will be ignored.
2984 The absolute value of the coefficient can be accessed through the @var{c}
2988 @subsection Examples
2990 Apply a denoise with a @option{sigma} of @code{4.5}:
2995 The same operation can be achieved using the expression system:
2997 dctdnoiz=e='gte(c, 4.5*3)'
3003 Drop duplicated frames at regular intervals.
3005 The filter accepts the following options:
3009 Set the number of frames from which one will be dropped. Setting this to
3010 @var{N} means one frame in every batch of @var{N} frames will be dropped.
3011 Default is @code{5}.
3014 Set the threshold for duplicate detection. If the difference metric for a frame
3015 is less than or equal to this value, then it is declared as duplicate. Default
3019 Set scene change threshold. Default is @code{15}.
3023 Set the size of the x and y-axis blocks used during metric calculations.
3024 Larger blocks give better noise suppression, but also give worse detection of
3025 small movements. Must be a power of two. Default is @code{32}.
3028 Mark main input as a pre-processed input and activate clean source input
3029 stream. This allows the input to be pre-processed with various filters to help
3030 the metrics calculation while keeping the frame selection lossless. When set to
3031 @code{1}, the first stream is for the pre-processed input, and the second
3032 stream is the clean source from where the kept frames are chosen. Default is
3036 Set whether or not chroma is considered in the metric calculations. Default is
3042 Suppress a TV station logo by a simple interpolation of the surrounding
3043 pixels. Just set a rectangle covering the logo and watch it disappear
3044 (and sometimes something even uglier appear - your mileage may vary).
3046 This filter accepts the following options:
3051 Specify the top left corner coordinates of the logo. They must be
3056 Specify the width and height of the logo to clear. They must be
3060 Specify the thickness of the fuzzy edge of the rectangle (added to
3061 @var{w} and @var{h}). The default value is 4.
3064 When set to 1, a green rectangle is drawn on the screen to simplify
3065 finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters.
3066 The default value is 0.
3068 The rectangle is drawn on the outermost pixels which will be (partly)
3069 replaced with interpolated values. The values of the next pixels
3070 immediately outside this rectangle in each direction will be used to
3071 compute the interpolated pixel values inside the rectangle.
3075 @subsection Examples
3079 Set a rectangle covering the area with top left corner coordinates 0,0
3080 and size 100x77, setting a band of size 10:
3082 delogo=x=0:y=0:w=100:h=77:band=10
3089 Attempt to fix small changes in horizontal and/or vertical shift. This
3090 filter helps remove camera shake from hand-holding a camera, bumping a
3091 tripod, moving on a vehicle, etc.
3093 The filter accepts the following options:
3101 Specify a rectangular area where to limit the search for motion
3103 If desired the search for motion vectors can be limited to a
3104 rectangular area of the frame defined by its top left corner, width
3105 and height. These parameters have the same meaning as the drawbox
3106 filter which can be used to visualise the position of the bounding
3109 This is useful when simultaneous movement of subjects within the frame
3110 might be confused for camera motion by the motion vector search.
3112 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
3113 then the full frame is used. This allows later options to be set
3114 without specifying the bounding box for the motion vector search.
3116 Default - search the whole frame.
3120 Specify the maximum extent of movement in x and y directions in the
3121 range 0-64 pixels. Default 16.
3124 Specify how to generate pixels to fill blanks at the edge of the
3125 frame. Available values are:
3128 Fill zeroes at blank locations
3130 Original image at blank locations
3132 Extruded edge value at blank locations
3134 Mirrored edge at blank locations
3136 Default value is @samp{mirror}.
3139 Specify the blocksize to use for motion search. Range 4-128 pixels,
3143 Specify the contrast threshold for blocks. Only blocks with more than
3144 the specified contrast (difference between darkest and lightest
3145 pixels) will be considered. Range 1-255, default 125.
3148 Specify the search strategy. Available values are:
3151 Set exhaustive search
3153 Set less exhaustive search.
3155 Default value is @samp{exhaustive}.
3158 If set then a detailed log of the motion search is written to the
3162 If set to 1, specify using OpenCL capabilities, only available if
3163 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
3169 Draw a colored box on the input image.
3171 This filter accepts the following options:
3176 The expressions which specify the top left corner coordinates of the box. Default to 0.
3180 The expressions which specify the width and height of the box, if 0 they are interpreted as
3181 the input width and height. Default to 0.
3184 Specify the color of the box to write, it can be the name of a color
3185 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
3186 value @code{invert} is used, the box edge color is the same as the
3187 video with inverted luma.
3190 The expression which sets the thickness of the box edge. Default value is @code{3}.
3192 See below for the list of accepted constants.
3195 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3196 following constants:
3200 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3204 horizontal and vertical chroma subsample values. For example for the
3205 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3209 The input width and height.
3212 The input sample aspect ratio.
3216 The x and y offset coordinates where the box is drawn.
3220 The width and height of the drawn box.
3223 The thickness of the drawn box.
3225 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3226 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3230 @subsection Examples
3234 Draw a black box around the edge of the input image:
3240 Draw a box with color red and an opacity of 50%:
3242 drawbox=10:20:200:60:red@@0.5
3245 The previous example can be specified as:
3247 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
3251 Fill the box with pink color:
3253 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
3257 Draw a 2-pixel red 2.40:1 mask:
3259 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
3265 Draw a grid on the input image.
3267 This filter accepts the following options:
3272 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
3276 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
3277 input width and height, respectively, minus @code{thickness}, so image gets
3278 framed. Default to 0.
3281 Specify the color of the grid, it can be the name of a color
3282 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
3283 value @code{invert} is used, the grid color is the same as the
3284 video with inverted luma.
3285 Note that you can append opacity value (in range of 0.0 - 1.0)
3286 to color name after @@ sign.
3289 The expression which sets the thickness of the grid line. Default value is @code{1}.
3291 See below for the list of accepted constants.
3294 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3295 following constants:
3299 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3303 horizontal and vertical chroma subsample values. For example for the
3304 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3308 The input grid cell width and height.
3311 The input sample aspect ratio.
3315 The x and y coordinates of some point of grid intersection (meant to configure offset).
3319 The width and height of the drawn cell.
3322 The thickness of the drawn cell.
3324 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3325 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3329 @subsection Examples
3333 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
3335 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
3339 Draw a white 3x3 grid with an opacity of 50%:
3341 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
3348 Draw text string or text from specified file on top of video using the
3349 libfreetype library.
3351 To enable compilation of this filter you need to configure FFmpeg with
3352 @code{--enable-libfreetype}.
3356 The description of the accepted parameters follows.
3361 Used to draw a box around text using background color.
3362 Value should be either 1 (enable) or 0 (disable).
3363 The default value of @var{box} is 0.
3366 The color to be used for drawing box around text.
3367 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
3368 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
3369 The default value of @var{boxcolor} is "white".
3372 Select how the @var{text} is expanded. Can be either @code{none},
3373 @code{strftime} (deprecated) or
3374 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
3378 If true, check and fix text coords to avoid clipping.
3381 The color to be used for drawing fonts.
3382 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
3383 (e.g. "0xff000033"), possibly followed by an alpha specifier.
3384 The default value of @var{fontcolor} is "black".
3387 The font file to be used for drawing text. Path must be included.
3388 This parameter is mandatory.
3391 The font size to be used for drawing text.
3392 The default value of @var{fontsize} is 16.
3395 Flags to be used for loading the fonts.
3397 The flags map the corresponding flags supported by libfreetype, and are
3398 a combination of the following values:
3405 @item vertical_layout
3406 @item force_autohint
3409 @item ignore_global_advance_width
3411 @item ignore_transform
3417 Default value is "render".
3419 For more information consult the documentation for the FT_LOAD_*
3423 The color to be used for drawing a shadow behind the drawn text. It
3424 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
3425 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
3426 The default value of @var{shadowcolor} is "black".
3430 The x and y offsets for the text shadow position with respect to the
3431 position of the text. They can be either positive or negative
3432 values. Default value for both is "0".
3435 The starting frame number for the n/frame_num variable. The default value
3439 The size in number of spaces to use for rendering the tab.
3443 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
3444 format. It can be used with or without text parameter. @var{timecode_rate}
3445 option must be specified.
3447 @item timecode_rate, rate, r
3448 Set the timecode frame rate (timecode only).
3451 The text string to be drawn. The text must be a sequence of UTF-8
3453 This parameter is mandatory if no file is specified with the parameter
3457 A text file containing text to be drawn. The text must be a sequence
3458 of UTF-8 encoded characters.
3460 This parameter is mandatory if no text string is specified with the
3461 parameter @var{text}.
3463 If both @var{text} and @var{textfile} are specified, an error is thrown.
3466 If set to 1, the @var{textfile} will be reloaded before each frame.
3467 Be sure to update it atomically, or it may be read partially, or even fail.
3471 The expressions which specify the offsets where text will be drawn
3472 within the video frame. They are relative to the top/left border of the
3475 The default value of @var{x} and @var{y} is "0".
3477 See below for the list of accepted constants and functions.
3480 The parameters for @var{x} and @var{y} are expressions containing the
3481 following constants and functions:
3485 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
3489 horizontal and vertical chroma subsample values. For example for the
3490 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3493 the height of each text line
3501 @item max_glyph_a, ascent
3502 the maximum distance from the baseline to the highest/upper grid
3503 coordinate used to place a glyph outline point, for all the rendered
3505 It is a positive value, due to the grid's orientation with the Y axis
3508 @item max_glyph_d, descent
3509 the maximum distance from the baseline to the lowest grid coordinate
3510 used to place a glyph outline point, for all the rendered glyphs.
3511 This is a negative value, due to the grid's orientation, with the Y axis
3515 maximum glyph height, that is the maximum height for all the glyphs
3516 contained in the rendered text, it is equivalent to @var{ascent} -
3520 maximum glyph width, that is the maximum width for all the glyphs
3521 contained in the rendered text
3524 the number of input frame, starting from 0
3526 @item rand(min, max)
3527 return a random number included between @var{min} and @var{max}
3530 input sample aspect ratio
3533 timestamp expressed in seconds, NAN if the input timestamp is unknown
3536 the height of the rendered text
3539 the width of the rendered text
3543 the x and y offset coordinates where the text is drawn.
3545 These parameters allow the @var{x} and @var{y} expressions to refer
3546 each other, so you can for example specify @code{y=x/dar}.
3549 If libavfilter was built with @code{--enable-fontconfig}, then
3550 @option{fontfile} can be a fontconfig pattern or omitted.
3552 @anchor{drawtext_expansion}
3553 @subsection Text expansion
3555 If @option{expansion} is set to @code{strftime},
3556 the filter recognizes strftime() sequences in the provided text and
3557 expands them accordingly. Check the documentation of strftime(). This
3558 feature is deprecated.
3560 If @option{expansion} is set to @code{none}, the text is printed verbatim.
3562 If @option{expansion} is set to @code{normal} (which is the default),
3563 the following expansion mechanism is used.
3565 The backslash character '\', followed by any character, always expands to
3566 the second character.
3568 Sequence of the form @code{%@{...@}} are expanded. The text between the
3569 braces is a function name, possibly followed by arguments separated by ':'.
3570 If the arguments contain special characters or delimiters (':' or '@}'),
3571 they should be escaped.
3573 Note that they probably must also be escaped as the value for the
3574 @option{text} option in the filter argument string and as the filter
3575 argument in the filtergraph description, and possibly also for the shell,
3576 that makes up to four levels of escaping; using a text file avoids these
3579 The following functions are available:
3584 The expression evaluation result.
3586 It must take one argument specifying the expression to be evaluated,
3587 which accepts the same constants and functions as the @var{x} and
3588 @var{y} values. Note that not all constants should be used, for
3589 example the text size is not known when evaluating the expression, so
3590 the constants @var{text_w} and @var{text_h} will have an undefined
3594 The time at which the filter is running, expressed in UTC.
3595 It can accept an argument: a strftime() format string.
3598 The time at which the filter is running, expressed in the local time zone.
3599 It can accept an argument: a strftime() format string.
3602 Frame metadata. It must take one argument specifying metadata key.
3605 The frame number, starting from 0.
3608 A 1 character description of the current picture type.
3611 The timestamp of the current frame, in seconds, with microsecond accuracy.
3615 @subsection Examples
3619 Draw "Test Text" with font FreeSerif, using the default values for the
3620 optional parameters.
3623 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
3627 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
3628 and y=50 (counting from the top-left corner of the screen), text is
3629 yellow with a red box around it. Both the text and the box have an
3633 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
3634 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
3637 Note that the double quotes are not necessary if spaces are not used
3638 within the parameter list.
3641 Show the text at the center of the video frame:
3643 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
3647 Show a text line sliding from right to left in the last row of the video
3648 frame. The file @file{LONG_LINE} is assumed to contain a single line
3651 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3655 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3657 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3661 Draw a single green letter "g", at the center of the input video.
3662 The glyph baseline is placed at half screen height.
3664 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3668 Show text for 1 second every 3 seconds:
3670 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
3674 Use fontconfig to set the font. Note that the colons need to be escaped.
3676 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3680 Print the date of a real-time encoding (see strftime(3)):
3682 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3687 For more information about libfreetype, check:
3688 @url{http://www.freetype.org/}.
3690 For more information about fontconfig, check:
3691 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3695 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3697 The filter accepts the following options:
3702 Set low and high threshold values used by the Canny thresholding
3705 The high threshold selects the "strong" edge pixels, which are then
3706 connected through 8-connectivity with the "weak" edge pixels selected
3707 by the low threshold.
3709 @var{low} and @var{high} threshold values must be choosen in the range
3710 [0,1], and @var{low} should be lesser or equal to @var{high}.
3712 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3718 edgedetect=low=0.1:high=0.4
3721 @section extractplanes
3723 Extract color channel components from input video stream into
3724 separate grayscale video streams.
3726 The filter accepts the following option:
3730 Set plane(s) to extract.
3732 Available values for planes are:
3743 Choosing planes not available in the input will result in an error.
3744 That means you cannot select @code{r}, @code{g}, @code{b} planes
3745 with @code{y}, @code{u}, @code{v} planes at same time.
3748 @subsection Examples
3752 Extract luma, u and v color channel component from input video frame
3753 into 3 grayscale outputs:
3755 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
3761 Apply fade-in/out effect to input video.
3763 This filter accepts the following options:
3767 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3769 Default is @code{in}.
3771 @item start_frame, s
3772 Specify the number of the start frame for starting to apply the fade
3773 effect. Default is 0.
3776 The number of frames for which the fade effect has to last. At the end of the
3777 fade-in effect the output video will have the same intensity as the input video,
3778 at the end of the fade-out transition the output video will be completely black.
3782 If set to 1, fade only alpha channel, if one exists on the input.
3785 @item start_time, st
3786 Specify the timestamp (in seconds) of the frame to start to apply the fade
3787 effect. If both start_frame and start_time are specified, the fade will start at
3788 whichever comes last. Default is 0.
3791 The number of seconds for which the fade effect has to last. At the end of the
3792 fade-in effect the output video will have the same intensity as the input video,
3793 at the end of the fade-out transition the output video will be completely black.
3794 If both duration and nb_frames are specified, duration is used. Default is 0.
3797 @subsection Examples
3801 Fade in first 30 frames of video:
3806 The command above is equivalent to:
3812 Fade out last 45 frames of a 200-frame video:
3815 fade=type=out:start_frame=155:nb_frames=45
3819 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3821 fade=in:0:25, fade=out:975:25
3825 Make first 5 frames black, then fade in from frame 5-24:
3831 Fade in alpha over first 25 frames of video:
3833 fade=in:0:25:alpha=1
3837 Make first 5.5 seconds black, then fade in for 0.5 seconds:
3839 fade=t=in:st=5.5:d=0.5
3846 Extract a single field from an interlaced image using stride
3847 arithmetic to avoid wasting CPU time. The output frames are marked as
3850 The filter accepts the following options:
3854 Specify whether to extract the top (if the value is @code{0} or
3855 @code{top}) or the bottom field (if the value is @code{1} or
3861 Field matching filter for inverse telecine. It is meant to reconstruct the
3862 progressive frames from a telecined stream. The filter does not drop duplicated
3863 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
3864 followed by a decimation filter such as @ref{decimate} in the filtergraph.
3866 The separation of the field matching and the decimation is notably motivated by
3867 the possibility of inserting a de-interlacing filter fallback between the two.
3868 If the source has mixed telecined and real interlaced content,
3869 @code{fieldmatch} will not be able to match fields for the interlaced parts.
3870 But these remaining combed frames will be marked as interlaced, and thus can be
3871 de-interlaced by a later filter such as @ref{yadif} before decimation.
3873 In addition to the various configuration options, @code{fieldmatch} can take an
3874 optional second stream, activated through the @option{ppsrc} option. If
3875 enabled, the frames reconstruction will be based on the fields and frames from
3876 this second stream. This allows the first input to be pre-processed in order to
3877 help the various algorithms of the filter, while keeping the output lossless
3878 (assuming the fields are matched properly). Typically, a field-aware denoiser,
3879 or brightness/contrast adjustments can help.
3881 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
3882 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
3883 which @code{fieldmatch} is based on. While the semantic and usage are very
3884 close, some behaviour and options names can differ.
3886 The filter accepts the following options:
3890 Specify the assumed field order of the input stream. Available values are:
3894 Auto detect parity (use FFmpeg's internal parity value).
3896 Assume bottom field first.
3898 Assume top field first.
3901 Note that it is sometimes recommended not to trust the parity announced by the
3904 Default value is @var{auto}.
3907 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
3908 sense that it won't risk creating jerkiness due to duplicate frames when
3909 possible, but if there are bad edits or blended fields it will end up
3910 outputting combed frames when a good match might actually exist. On the other
3911 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
3912 but will almost always find a good frame if there is one. The other values are
3913 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
3914 jerkiness and creating duplicate frames versus finding good matches in sections
3915 with bad edits, orphaned fields, blended fields, etc.
3917 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
3919 Available values are:
3923 2-way matching (p/c)
3925 2-way matching, and trying 3rd match if still combed (p/c + n)
3927 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
3929 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
3930 still combed (p/c + n + u/b)
3932 3-way matching (p/c/n)
3934 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
3935 detected as combed (p/c/n + u/b)
3938 The parenthesis at the end indicate the matches that would be used for that
3939 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
3942 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
3945 Default value is @var{pc_n}.
3948 Mark the main input stream as a pre-processed input, and enable the secondary
3949 input stream as the clean source to pick the fields from. See the filter
3950 introduction for more details. It is similar to the @option{clip2} feature from
3953 Default value is @code{0} (disabled).
3956 Set the field to match from. It is recommended to set this to the same value as
3957 @option{order} unless you experience matching failures with that setting. In
3958 certain circumstances changing the field that is used to match from can have a
3959 large impact on matching performance. Available values are:
3963 Automatic (same value as @option{order}).
3965 Match from the bottom field.
3967 Match from the top field.
3970 Default value is @var{auto}.
3973 Set whether or not chroma is included during the match comparisons. In most
3974 cases it is recommended to leave this enabled. You should set this to @code{0}
3975 only if your clip has bad chroma problems such as heavy rainbowing or other
3976 artifacts. Setting this to @code{0} could also be used to speed things up at
3977 the cost of some accuracy.
3979 Default value is @code{1}.
3983 These define an exclusion band which excludes the lines between @option{y0} and
3984 @option{y1} from being included in the field matching decision. An exclusion
3985 band can be used to ignore subtitles, a logo, or other things that may
3986 interfere with the matching. @option{y0} sets the starting scan line and
3987 @option{y1} sets the ending line; all lines in between @option{y0} and
3988 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
3989 @option{y0} and @option{y1} to the same value will disable the feature.
3990 @option{y0} and @option{y1} defaults to @code{0}.
3993 Set the scene change detection threshold as a percentage of maximum change on
3994 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
3995 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
3996 @option{scthresh} is @code{[0.0, 100.0]}.
3998 Default value is @code{12.0}.
4001 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
4002 account the combed scores of matches when deciding what match to use as the
4003 final match. Available values are:
4007 No final matching based on combed scores.
4009 Combed scores are only used when a scene change is detected.
4011 Use combed scores all the time.
4014 Default is @var{sc}.
4017 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
4018 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
4019 Available values are:
4023 No forced calculation.
4025 Force p/c/n calculations.
4027 Force p/c/n/u/b calculations.
4030 Default value is @var{none}.
4033 This is the area combing threshold used for combed frame detection. This
4034 essentially controls how "strong" or "visible" combing must be to be detected.
4035 Larger values mean combing must be more visible and smaller values mean combing
4036 can be less visible or strong and still be detected. Valid settings are from
4037 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
4038 be detected as combed). This is basically a pixel difference value. A good
4039 range is @code{[8, 12]}.
4041 Default value is @code{9}.
4044 Sets whether or not chroma is considered in the combed frame decision. Only
4045 disable this if your source has chroma problems (rainbowing, etc.) that are
4046 causing problems for the combed frame detection with chroma enabled. Actually,
4047 using @option{chroma}=@var{0} is usually more reliable, except for the case
4048 where there is chroma only combing in the source.
4050 Default value is @code{0}.
4054 Respectively set the x-axis and y-axis size of the window used during combed
4055 frame detection. This has to do with the size of the area in which
4056 @option{combpel} pixels are required to be detected as combed for a frame to be
4057 declared combed. See the @option{combpel} parameter description for more info.
4058 Possible values are any number that is a power of 2 starting at 4 and going up
4061 Default value is @code{16}.
4064 The number of combed pixels inside any of the @option{blocky} by
4065 @option{blockx} size blocks on the frame for the frame to be detected as
4066 combed. While @option{cthresh} controls how "visible" the combing must be, this
4067 setting controls "how much" combing there must be in any localized area (a
4068 window defined by the @option{blockx} and @option{blocky} settings) on the
4069 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
4070 which point no frames will ever be detected as combed). This setting is known
4071 as @option{MI} in TFM/VFM vocabulary.
4073 Default value is @code{80}.
4076 @anchor{p/c/n/u/b meaning}
4077 @subsection p/c/n/u/b meaning
4079 @subsubsection p/c/n
4081 We assume the following telecined stream:
4084 Top fields: 1 2 2 3 4
4085 Bottom fields: 1 2 3 4 4
4088 The numbers correspond to the progressive frame the fields relate to. Here, the
4089 first two frames are progressive, the 3rd and 4th are combed, and so on.
4091 When @code{fieldmatch} is configured to run a matching from bottom
4092 (@option{field}=@var{bottom}) this is how this input stream get transformed:
4097 B 1 2 3 4 4 <-- matching reference
4106 As a result of the field matching, we can see that some frames get duplicated.
4107 To perform a complete inverse telecine, you need to rely on a decimation filter
4108 after this operation. See for instance the @ref{decimate} filter.
4110 The same operation now matching from top fields (@option{field}=@var{top})
4115 T 1 2 2 3 4 <-- matching reference
4125 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
4126 basically, they refer to the frame and field of the opposite parity:
4129 @item @var{p} matches the field of the opposite parity in the previous frame
4130 @item @var{c} matches the field of the opposite parity in the current frame
4131 @item @var{n} matches the field of the opposite parity in the next frame
4136 The @var{u} and @var{b} matching are a bit special in the sense that they match
4137 from the opposite parity flag. In the following examples, we assume that we are
4138 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
4139 'x' is placed above and below each matched fields.
4141 With bottom matching (@option{field}=@var{bottom}):
4146 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4147 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4155 With top matching (@option{field}=@var{top}):
4160 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
4161 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
4169 @subsection Examples
4171 Simple IVTC of a top field first telecined stream:
4173 fieldmatch=order=tff:combmatch=none, decimate
4176 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
4178 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
4183 Transform the field order of the input video.
4185 This filter accepts the following options:
4190 Output field order. Valid values are @var{tff} for top field first or @var{bff}
4191 for bottom field first.
4194 Default value is @samp{tff}.
4196 Transformation is achieved by shifting the picture content up or down
4197 by one line, and filling the remaining line with appropriate picture content.
4198 This method is consistent with most broadcast field order converters.
4200 If the input video is not flagged as being interlaced, or it is already
4201 flagged as being of the required output field order then this filter does
4202 not alter the incoming video.
4204 This filter is very useful when converting to or from PAL DV material,
4205 which is bottom field first.
4209 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
4214 Buffer input images and send them when they are requested.
4216 This filter is mainly useful when auto-inserted by the libavfilter
4219 The filter does not take parameters.
4224 Convert the input video to one of the specified pixel formats.
4225 Libavfilter will try to pick one that is supported for the input to
4228 This filter accepts the following parameters:
4232 A '|'-separated list of pixel format names, for example
4233 "pix_fmts=yuv420p|monow|rgb24".
4237 @subsection Examples
4241 Convert the input video to the format @var{yuv420p}
4243 format=pix_fmts=yuv420p
4246 Convert the input video to any of the formats in the list
4248 format=pix_fmts=yuv420p|yuv444p|yuv410p
4254 Convert the video to specified constant frame rate by duplicating or dropping
4255 frames as necessary.
4257 This filter accepts the following named parameters:
4261 Desired output frame rate. The default is @code{25}.
4266 Possible values are:
4269 zero round towards 0
4273 round towards -infinity
4275 round towards +infinity
4279 The default is @code{near}.
4282 Assume the first PTS should be the given value, in seconds. This allows for
4283 padding/trimming at the start of stream. By default, no assumption is made
4284 about the first frame's expected PTS, so no padding or trimming is done.
4285 For example, this could be set to 0 to pad the beginning with duplicates of
4286 the first frame if a video stream starts after the audio stream or to trim any
4287 frames with a negative PTS.
4291 Alternatively, the options can be specified as a flat string:
4292 @var{fps}[:@var{round}].
4294 See also the @ref{setpts} filter.
4296 @subsection Examples
4300 A typical usage in order to set the fps to 25:
4306 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
4308 fps=fps=film:round=near
4314 Select one frame every N-th frame.
4316 This filter accepts the following option:
4319 Select frame after every @code{step} frames.
4320 Allowed values are positive integers higher than 0. Default value is @code{1}.
4326 Apply a frei0r effect to the input video.
4328 To enable compilation of this filter you need to install the frei0r
4329 header and configure FFmpeg with @code{--enable-frei0r}.
4331 This filter accepts the following options:
4336 The name to the frei0r effect to load. If the environment variable
4337 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
4338 directories specified by the colon separated list in @env{FREIOR_PATH},
4339 otherwise in the standard frei0r paths, which are in this order:
4340 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
4341 @file{/usr/lib/frei0r-1/}.
4344 A '|'-separated list of parameters to pass to the frei0r effect.
4348 A frei0r effect parameter can be a boolean (whose values are specified
4349 with "y" and "n"), a double, a color (specified by the syntax
4350 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
4351 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
4352 description), a position (specified by the syntax @var{X}/@var{Y},
4353 @var{X} and @var{Y} being float numbers) and a string.
4355 The number and kind of parameters depend on the loaded effect. If an
4356 effect parameter is not specified the default value is set.
4358 @subsection Examples
4362 Apply the distort0r effect, set the first two double parameters:
4364 frei0r=filter_name=distort0r:filter_params=0.5|0.01
4368 Apply the colordistance effect, take a color as first parameter:
4370 frei0r=colordistance:0.2/0.3/0.4
4371 frei0r=colordistance:violet
4372 frei0r=colordistance:0x112233
4376 Apply the perspective effect, specify the top left and top right image
4379 frei0r=perspective:0.2/0.2|0.8/0.2
4383 For more information see:
4384 @url{http://frei0r.dyne.org}
4388 The filter accepts the following options:
4392 Set the luminance expression.
4394 Set the chrominance blue expression.
4396 Set the chrominance red expression.
4398 Set the alpha expression.
4400 Set the red expression.
4402 Set the green expression.
4404 Set the blue expression.
4407 The colorspace is selected according to the specified options. If one
4408 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
4409 options is specified, the filter will automatically select a YCbCr
4410 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
4411 @option{blue_expr} options is specified, it will select an RGB
4414 If one of the chrominance expression is not defined, it falls back on the other
4415 one. If no alpha expression is specified it will evaluate to opaque value.
4416 If none of chrominance expressions are specified, they will evaluate
4417 to the luminance expression.
4419 The expressions can use the following variables and functions:
4423 The sequential number of the filtered frame, starting from @code{0}.
4427 The coordinates of the current sample.
4431 The width and height of the image.
4435 Width and height scale depending on the currently filtered plane. It is the
4436 ratio between the corresponding luma plane number of pixels and the current
4437 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4438 @code{0.5,0.5} for chroma planes.
4441 Time of the current frame, expressed in seconds.
4444 Return the value of the pixel at location (@var{x},@var{y}) of the current
4448 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
4452 Return the value of the pixel at location (@var{x},@var{y}) of the
4453 blue-difference chroma plane. Return 0 if there is no such plane.
4456 Return the value of the pixel at location (@var{x},@var{y}) of the
4457 red-difference chroma plane. Return 0 if there is no such plane.
4462 Return the value of the pixel at location (@var{x},@var{y}) of the
4463 red/green/blue component. Return 0 if there is no such component.
4466 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
4467 plane. Return 0 if there is no such plane.
4470 For functions, if @var{x} and @var{y} are outside the area, the value will be
4471 automatically clipped to the closer edge.
4473 @subsection Examples
4477 Flip the image horizontally:
4483 Generate a bidimensional sine wave, with angle @code{PI/3} and a
4484 wavelength of 100 pixels:
4486 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
4490 Generate a fancy enigmatic moving light:
4492 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
4496 Generate a quick emboss effect:
4498 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
4502 Modify RGB components depending on pixel position:
4504 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
4510 Fix the banding artifacts that are sometimes introduced into nearly flat
4511 regions by truncation to 8bit color depth.
4512 Interpolate the gradients that should go where the bands are, and
4515 This filter is designed for playback only. Do not use it prior to
4516 lossy compression, because compression tends to lose the dither and
4517 bring back the bands.
4519 This filter accepts the following options:
4524 The maximum amount by which the filter will change any one pixel. Also the
4525 threshold for detecting nearly flat regions. Acceptable values range from .51 to
4526 64, default value is 1.2, out-of-range values will be clipped to the valid
4530 The neighborhood to fit the gradient to. A larger radius makes for smoother
4531 gradients, but also prevents the filter from modifying the pixels near detailed
4532 regions. Acceptable values are 8-32, default value is 16, out-of-range values
4533 will be clipped to the valid range.
4537 Alternatively, the options can be specified as a flat string:
4538 @var{strength}[:@var{radius}]
4540 @subsection Examples
4544 Apply the filter with a @code{3.5} strength and radius of @code{8}:
4550 Specify radius, omitting the strength (which will fall-back to the default
4561 Apply a Hald CLUT to a video stream.
4563 First input is the video stream to process, and second one is the Hald CLUT.
4564 The Hald CLUT input can be a simple picture or a complete video stream.
4566 The filter accepts the following options:
4570 Force termination when the shortest input terminates. Default is @code{0}.
4572 Continue applying the last CLUT after the end of the stream. A value of
4573 @code{0} disable the filter after the last frame of the CLUT is reached.
4574 Default is @code{1}.
4577 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
4578 filters share the same internals).
4580 More information about the Hald CLUT can be found on Eskil Steenberg's website
4581 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
4583 @subsection Workflow examples
4585 @subsubsection Hald CLUT video stream
4587 Generate an identity Hald CLUT stream altered with various effects:
4589 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
4592 Note: make sure you use a lossless codec.
4594 Then use it with @code{haldclut} to apply it on some random stream:
4596 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
4599 The Hald CLUT will be applied to the 10 first seconds (duration of
4600 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
4601 to the remaining frames of the @code{mandelbrot} stream.
4603 @subsubsection Hald CLUT with preview
4605 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
4606 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
4607 biggest possible square starting at the top left of the picture. The remaining
4608 padding pixels (bottom or right) will be ignored. This area can be used to add
4609 a preview of the Hald CLUT.
4611 Typically, the following generated Hald CLUT will be supported by the
4612 @code{haldclut} filter:
4615 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
4616 pad=iw+320 [padded_clut];
4617 smptebars=s=320x256, split [a][b];
4618 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
4619 [main][b] overlay=W-320" -frames:v 1 clut.png
4622 It contains the original and a preview of the effect of the CLUT: SMPTE color
4623 bars are displayed on the right-top, and below the same color bars processed by
4626 Then, the effect of this Hald CLUT can be visualized with:
4628 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
4633 Flip the input video horizontally.
4635 For example to horizontally flip the input video with @command{ffmpeg}:
4637 ffmpeg -i in.avi -vf "hflip" out.avi
4641 This filter applies a global color histogram equalization on a
4644 It can be used to correct video that has a compressed range of pixel
4645 intensities. The filter redistributes the pixel intensities to
4646 equalize their distribution across the intensity range. It may be
4647 viewed as an "automatically adjusting contrast filter". This filter is
4648 useful only for correcting degraded or poorly captured source
4651 The filter accepts the following options:
4655 Determine the amount of equalization to be applied. As the strength
4656 is reduced, the distribution of pixel intensities more-and-more
4657 approaches that of the input frame. The value must be a float number
4658 in the range [0,1] and defaults to 0.200.
4661 Set the maximum intensity that can generated and scale the output
4662 values appropriately. The strength should be set as desired and then
4663 the intensity can be limited if needed to avoid washing-out. The value
4664 must be a float number in the range [0,1] and defaults to 0.210.
4667 Set the antibanding level. If enabled the filter will randomly vary
4668 the luminance of output pixels by a small amount to avoid banding of
4669 the histogram. Possible values are @code{none}, @code{weak} or
4670 @code{strong}. It defaults to @code{none}.
4675 Compute and draw a color distribution histogram for the input video.
4677 The computed histogram is a representation of distribution of color components
4680 The filter accepts the following options:
4686 It accepts the following values:
4689 standard histogram that display color components distribution in an image.
4690 Displays color graph for each color component. Shows distribution
4691 of the Y, U, V, A or G, B, R components, depending on input format,
4692 in current frame. Bellow each graph is color component scale meter.
4695 chroma values in vectorscope, if brighter more such chroma values are
4696 distributed in an image.
4697 Displays chroma values (U/V color placement) in two dimensional graph
4698 (which is called a vectorscope). It can be used to read of the hue and
4699 saturation of the current frame. At a same time it is a histogram.
4700 The whiter a pixel in the vectorscope, the more pixels of the input frame
4701 correspond to that pixel (that is the more pixels have this chroma value).
4702 The V component is displayed on the horizontal (X) axis, with the leftmost
4703 side being V = 0 and the rightmost side being V = 255.
4704 The U component is displayed on the vertical (Y) axis, with the top
4705 representing U = 0 and the bottom representing U = 255.
4707 The position of a white pixel in the graph corresponds to the chroma value
4708 of a pixel of the input clip. So the graph can be used to read of the
4709 hue (color flavor) and the saturation (the dominance of the hue in the color).
4710 As the hue of a color changes, it moves around the square. At the center of
4711 the square, the saturation is zero, which means that the corresponding pixel
4712 has no color. If you increase the amount of a specific color, while leaving
4713 the other colors unchanged, the saturation increases, and you move towards
4714 the edge of the square.
4717 chroma values in vectorscope, similar as @code{color} but actual chroma values
4721 per row/column color component graph. In row mode graph in the left side represents
4722 color component value 0 and right side represents value = 255. In column mode top
4723 side represents color component value = 0 and bottom side represents value = 255.
4725 Default value is @code{levels}.
4728 Set height of level in @code{levels}. Default value is @code{200}.
4729 Allowed range is [50, 2048].
4732 Set height of color scale in @code{levels}. Default value is @code{12}.
4733 Allowed range is [0, 40].
4736 Set step for @code{waveform} mode. Smaller values are useful to find out how much
4737 of same luminance values across input rows/columns are distributed.
4738 Default value is @code{10}. Allowed range is [1, 255].
4741 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
4742 Default is @code{row}.
4745 Set display mode for @code{waveform} and @code{levels}.
4746 It accepts the following values:
4749 Display separate graph for the color components side by side in
4750 @code{row} waveform mode or one below other in @code{column} waveform mode
4751 for @code{waveform} histogram mode. For @code{levels} histogram mode
4752 per color component graphs are placed one bellow other.
4754 This display mode in @code{waveform} histogram mode makes it easy to spot
4755 color casts in the highlights and shadows of an image, by comparing the
4756 contours of the top and the bottom of each waveform.
4757 Since whites, grays, and blacks are characterized by
4758 exactly equal amounts of red, green, and blue, neutral areas of the
4759 picture should display three waveforms of roughly equal width/height.
4760 If not, the correction is easy to make by making adjustments to level the
4764 Presents information that's identical to that in the @code{parade}, except
4765 that the graphs representing color components are superimposed directly
4768 This display mode in @code{waveform} histogram mode can make it easier to spot
4769 the relative differences or similarities in overlapping areas of the color
4770 components that are supposed to be identical, such as neutral whites, grays,
4773 Default is @code{parade}.
4776 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
4777 Default is @code{linear}.
4780 @subsection Examples
4785 Calculate and draw histogram:
4787 ffplay -i input -vf histogram
4795 High precision/quality 3d denoise filter. This filter aims to reduce
4796 image noise producing smooth images and making still images really
4797 still. It should enhance compressibility.
4799 It accepts the following optional parameters:
4803 a non-negative float number which specifies spatial luma strength,
4806 @item chroma_spatial
4807 a non-negative float number which specifies spatial chroma strength,
4808 defaults to 3.0*@var{luma_spatial}/4.0
4811 a float number which specifies luma temporal strength, defaults to
4812 6.0*@var{luma_spatial}/4.0
4815 a float number which specifies chroma temporal strength, defaults to
4816 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
4821 Modify the hue and/or the saturation of the input.
4823 This filter accepts the following options:
4827 Specify the hue angle as a number of degrees. It accepts an expression,
4828 and defaults to "0".
4831 Specify the saturation in the [-10,10] range. It accepts an expression and
4835 Specify the hue angle as a number of radians. It accepts an
4836 expression, and defaults to "0".
4839 Specify the brightness in the [-10,10] range. It accepts an expression and
4843 @option{h} and @option{H} are mutually exclusive, and can't be
4844 specified at the same time.
4846 The @option{b}, @option{h}, @option{H} and @option{s} option values are
4847 expressions containing the following constants:
4851 frame count of the input frame starting from 0
4854 presentation timestamp of the input frame expressed in time base units
4857 frame rate of the input video, NAN if the input frame rate is unknown
4860 timestamp expressed in seconds, NAN if the input timestamp is unknown
4863 time base of the input video
4866 @subsection Examples
4870 Set the hue to 90 degrees and the saturation to 1.0:
4876 Same command but expressing the hue in radians:
4882 Rotate hue and make the saturation swing between 0
4883 and 2 over a period of 1 second:
4885 hue="H=2*PI*t: s=sin(2*PI*t)+1"
4889 Apply a 3 seconds saturation fade-in effect starting at 0:
4894 The general fade-in expression can be written as:
4896 hue="s=min(0\, max((t-START)/DURATION\, 1))"
4900 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
4902 hue="s=max(0\, min(1\, (8-t)/3))"
4905 The general fade-out expression can be written as:
4907 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
4912 @subsection Commands
4914 This filter supports the following commands:
4920 Modify the hue and/or the saturation and/or brightness of the input video.
4921 The command accepts the same syntax of the corresponding option.
4923 If the specified expression is not valid, it is kept at its current
4929 Detect video interlacing type.
4931 This filter tries to detect if the input is interlaced or progressive,
4932 top or bottom field first.
4934 The filter accepts the following options:
4938 Set interlacing threshold.
4940 Set progressive threshold.
4945 Deinterleave or interleave fields.
4947 This filter allows to process interlaced images fields without
4948 deinterlacing them. Deinterleaving splits the input frame into 2
4949 fields (so called half pictures). Odd lines are moved to the top
4950 half of the output image, even lines to the bottom half.
4951 You can process (filter) them independently and then re-interleave them.
4953 The filter accepts the following options:
4957 @item chroma_mode, c
4959 Available values for @var{luma_mode}, @var{chroma_mode} and
4960 @var{alpha_mode} are:
4966 @item deinterleave, d
4967 Deinterleave fields, placing one above the other.
4970 Interleave fields. Reverse the effect of deinterleaving.
4972 Default value is @code{none}.
4975 @item chroma_swap, cs
4976 @item alpha_swap, as
4977 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
4982 Simple interlacing filter from progressive contents. This interleaves upper (or
4983 lower) lines from odd frames with lower (or upper) lines from even frames,
4984 halving the frame rate and preserving image height.
4987 Original Original New Frame
4988 Frame 'j' Frame 'j+1' (tff)
4989 ========== =========== ==================
4990 Line 0 --------------------> Frame 'j' Line 0
4991 Line 1 Line 1 ----> Frame 'j+1' Line 1
4992 Line 2 ---------------------> Frame 'j' Line 2
4993 Line 3 Line 3 ----> Frame 'j+1' Line 3
4995 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
4998 It accepts the following optional parameters:
5002 determines whether the interlaced frame is taken from the even (tff - default)
5003 or odd (bff) lines of the progressive frame.
5006 Enable (default) or disable the vertical lowpass filter to avoid twitter
5007 interlacing and reduce moire patterns.
5012 Deinterlace input video by applying Donald Graft's adaptive kernel
5013 deinterling. Work on interlaced parts of a video to produce
5016 The description of the accepted parameters follows.
5020 Set the threshold which affects the filter's tolerance when
5021 determining if a pixel line must be processed. It must be an integer
5022 in the range [0,255] and defaults to 10. A value of 0 will result in
5023 applying the process on every pixels.
5026 Paint pixels exceeding the threshold value to white if set to 1.
5030 Set the fields order. Swap fields if set to 1, leave fields alone if
5034 Enable additional sharpening if set to 1. Default is 0.
5037 Enable twoway sharpening if set to 1. Default is 0.
5040 @subsection Examples
5044 Apply default values:
5046 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
5050 Enable additional sharpening:
5056 Paint processed pixels in white:
5065 Apply a 3D LUT to an input video.
5067 The filter accepts the following options:
5071 Set the 3D LUT file name.
5073 Currently supported formats:
5085 Select interpolation mode.
5087 Available values are:
5091 Use values from the nearest defined point.
5093 Interpolate values using the 8 points defining a cube.
5095 Interpolate values using a tetrahedron.
5099 @section lut, lutrgb, lutyuv
5101 Compute a look-up table for binding each pixel component input value
5102 to an output value, and apply it to input video.
5104 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
5105 to an RGB input video.
5107 These filters accept the following options:
5110 set first pixel component expression
5112 set second pixel component expression
5114 set third pixel component expression
5116 set fourth pixel component expression, corresponds to the alpha component
5119 set red component expression
5121 set green component expression
5123 set blue component expression
5125 alpha component expression
5128 set Y/luminance component expression
5130 set U/Cb component expression
5132 set V/Cr component expression
5135 Each of them specifies the expression to use for computing the lookup table for
5136 the corresponding pixel component values.
5138 The exact component associated to each of the @var{c*} options depends on the
5141 The @var{lut} filter requires either YUV or RGB pixel formats in input,
5142 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
5144 The expressions can contain the following constants and functions:
5149 the input width and height
5152 input value for the pixel component
5155 the input value clipped in the @var{minval}-@var{maxval} range
5158 maximum value for the pixel component
5161 minimum value for the pixel component
5164 the negated value for the pixel component value clipped in the
5165 @var{minval}-@var{maxval} range , it corresponds to the expression
5166 "maxval-clipval+minval"
5169 the computed value in @var{val} clipped in the
5170 @var{minval}-@var{maxval} range
5172 @item gammaval(gamma)
5173 the computed gamma correction value of the pixel component value
5174 clipped in the @var{minval}-@var{maxval} range, corresponds to the
5176 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
5180 All expressions default to "val".
5182 @subsection Examples
5188 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
5189 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
5192 The above is the same as:
5194 lutrgb="r=negval:g=negval:b=negval"
5195 lutyuv="y=negval:u=negval:v=negval"
5205 Remove chroma components, turns the video into a graytone image:
5207 lutyuv="u=128:v=128"
5211 Apply a luma burning effect:
5217 Remove green and blue components:
5223 Set a constant alpha channel value on input:
5225 format=rgba,lutrgb=a="maxval-minval/2"
5229 Correct luminance gamma by a 0.5 factor:
5231 lutyuv=y=gammaval(0.5)
5235 Discard least significant bits of luma:
5237 lutyuv=y='bitand(val, 128+64+32)'
5243 Apply motion-compensation deinterlacing.
5245 It needs one field per frame as input and must thus be used together
5246 with yadif=1/3 or equivalent.
5248 This filter accepts the following options:
5251 Set the deinterlacing mode.
5253 It accepts one of the following values:
5258 use iterative motion estimation
5260 like @samp{slow}, but use multiple reference frames.
5262 Default value is @samp{fast}.
5265 Set the picture field parity assumed for the input video. It must be
5266 one of the following values:
5270 assume top field first
5272 assume bottom field first
5275 Default value is @samp{bff}.
5278 Set per-block quantization parameter (QP) used by the internal
5281 Higher values should result in a smoother motion vector field but less
5282 optimal individual vectors. Default value is 1.
5287 Apply an MPlayer filter to the input video.
5289 This filter provides a wrapper around some of the filters of
5292 This wrapper is considered experimental. Some of the wrapped filters
5293 may not work properly and we may drop support for them, as they will
5294 be implemented natively into FFmpeg. Thus you should avoid
5295 depending on them when writing portable scripts.
5297 The filter accepts the parameters:
5298 @var{filter_name}[:=]@var{filter_params}
5300 @var{filter_name} is the name of a supported MPlayer filter,
5301 @var{filter_params} is a string containing the parameters accepted by
5304 The list of the currently supported filters follows:
5315 The parameter syntax and behavior for the listed filters are the same
5316 of the corresponding MPlayer filters. For detailed instructions check
5317 the "VIDEO FILTERS" section in the MPlayer manual.
5319 @subsection Examples
5323 Adjust gamma, brightness, contrast:
5329 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
5333 Drop frames that do not differ greatly from the previous frame in
5334 order to reduce frame rate.
5336 The main use of this filter is for very-low-bitrate encoding
5337 (e.g. streaming over dialup modem), but it could in theory be used for
5338 fixing movies that were inverse-telecined incorrectly.
5340 A description of the accepted options follows.
5344 Set the maximum number of consecutive frames which can be dropped (if
5345 positive), or the minimum interval between dropped frames (if
5346 negative). If the value is 0, the frame is dropped unregarding the
5347 number of previous sequentially dropped frames.
5354 Set the dropping threshold values.
5356 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
5357 represent actual pixel value differences, so a threshold of 64
5358 corresponds to 1 unit of difference for each pixel, or the same spread
5359 out differently over the block.
5361 A frame is a candidate for dropping if no 8x8 blocks differ by more
5362 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
5363 meaning the whole image) differ by more than a threshold of @option{lo}.
5365 Default value for @option{hi} is 64*12, default value for @option{lo} is
5366 64*5, and default value for @option{frac} is 0.33.
5374 This filter accepts an integer in input, if non-zero it negates the
5375 alpha component (if available). The default value in input is 0.
5379 Force libavfilter not to use any of the specified pixel formats for the
5380 input to the next filter.
5382 This filter accepts the following parameters:
5386 A '|'-separated list of pixel format names, for example
5387 "pix_fmts=yuv420p|monow|rgb24".
5391 @subsection Examples
5395 Force libavfilter to use a format different from @var{yuv420p} for the
5396 input to the vflip filter:
5398 noformat=pix_fmts=yuv420p,vflip
5402 Convert the input video to any of the formats not contained in the list:
5404 noformat=yuv420p|yuv444p|yuv410p
5410 Add noise on video input frame.
5412 The filter accepts the following options:
5420 Set noise seed for specific pixel component or all pixel components in case
5421 of @var{all_seed}. Default value is @code{123457}.
5423 @item all_strength, alls
5424 @item c0_strength, c0s
5425 @item c1_strength, c1s
5426 @item c2_strength, c2s
5427 @item c3_strength, c3s
5428 Set noise strength for specific pixel component or all pixel components in case
5429 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
5431 @item all_flags, allf
5436 Set pixel component flags or set flags for all components if @var{all_flags}.
5437 Available values for component flags are:
5440 averaged temporal noise (smoother)
5442 mix random noise with a (semi)regular pattern
5444 temporal noise (noise pattern changes between frames)
5446 uniform noise (gaussian otherwise)
5450 @subsection Examples
5452 Add temporal and uniform noise to input video:
5454 noise=alls=20:allf=t+u
5459 Pass the video source unchanged to the output.
5463 Apply video transform using libopencv.
5465 To enable this filter install libopencv library and headers and
5466 configure FFmpeg with @code{--enable-libopencv}.
5468 This filter accepts the following parameters:
5473 The name of the libopencv filter to apply.
5476 The parameters to pass to the libopencv filter. If not specified the default
5481 Refer to the official libopencv documentation for more precise
5483 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
5485 Follows the list of supported libopencv filters.
5490 Dilate an image by using a specific structuring element.
5491 This filter corresponds to the libopencv function @code{cvDilate}.
5493 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
5495 @var{struct_el} represents a structuring element, and has the syntax:
5496 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
5498 @var{cols} and @var{rows} represent the number of columns and rows of
5499 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
5500 point, and @var{shape} the shape for the structuring element, and
5501 can be one of the values "rect", "cross", "ellipse", "custom".
5503 If the value for @var{shape} is "custom", it must be followed by a
5504 string of the form "=@var{filename}". The file with name
5505 @var{filename} is assumed to represent a binary image, with each
5506 printable character corresponding to a bright pixel. When a custom
5507 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
5508 or columns and rows of the read file are assumed instead.
5510 The default value for @var{struct_el} is "3x3+0x0/rect".
5512 @var{nb_iterations} specifies the number of times the transform is
5513 applied to the image, and defaults to 1.
5515 Follow some example:
5517 # use the default values
5520 # dilate using a structuring element with a 5x5 cross, iterate two times
5521 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
5523 # read the shape from the file diamond.shape, iterate two times
5524 # the file diamond.shape may contain a pattern of characters like this:
5530 # the specified cols and rows are ignored (but not the anchor point coordinates)
5531 ocv=dilate:0x0+2x2/custom=diamond.shape|2
5536 Erode an image by using a specific structuring element.
5537 This filter corresponds to the libopencv function @code{cvErode}.
5539 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
5540 with the same syntax and semantics as the @ref{dilate} filter.
5544 Smooth the input video.
5546 The filter takes the following parameters:
5547 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
5549 @var{type} is the type of smooth filter to apply, and can be one of
5550 the following values: "blur", "blur_no_scale", "median", "gaussian",
5551 "bilateral". The default value is "gaussian".
5553 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
5554 parameters whose meanings depend on smooth type. @var{param1} and
5555 @var{param2} accept integer positive values or 0, @var{param3} and
5556 @var{param4} accept float values.
5558 The default value for @var{param1} is 3, the default value for the
5559 other parameters is 0.
5561 These parameters correspond to the parameters assigned to the
5562 libopencv function @code{cvSmooth}.
5567 Overlay one video on top of another.
5569 It takes two inputs and one output, the first input is the "main"
5570 video on which the second input is overlayed.
5572 This filter accepts the following parameters:
5574 A description of the accepted options follows.
5579 Set the expression for the x and y coordinates of the overlayed video
5580 on the main video. Default value is "0" for both expressions. In case
5581 the expression is invalid, it is set to a huge value (meaning that the
5582 overlay will not be displayed within the output visible area).
5585 Set when the expressions for @option{x}, and @option{y} are evaluated.
5587 It accepts the following values:
5590 only evaluate expressions once during the filter initialization or
5591 when a command is processed
5594 evaluate expressions for each incoming frame
5597 Default value is @samp{frame}.
5600 If set to 1, force the output to terminate when the shortest input
5601 terminates. Default value is 0.
5604 Set the format for the output video.
5606 It accepts the following values:
5618 Default value is @samp{yuv420}.
5620 @item rgb @emph{(deprecated)}
5621 If set to 1, force the filter to accept inputs in the RGB
5622 color space. Default value is 0. This option is deprecated, use
5623 @option{format} instead.
5626 If set to 1, force the filter to draw the last overlay frame over the
5627 main input until the end of the stream. A value of 0 disables this
5628 behavior. Default value is 1.
5631 The @option{x}, and @option{y} expressions can contain the following
5637 main input width and height
5641 overlay input width and height
5645 the computed values for @var{x} and @var{y}. They are evaluated for
5650 horizontal and vertical chroma subsample values of the output
5651 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
5655 the number of input frame, starting from 0
5658 the position in the file of the input frame, NAN if unknown
5661 timestamp expressed in seconds, NAN if the input timestamp is unknown
5664 Note that the @var{n}, @var{pos}, @var{t} variables are available only
5665 when evaluation is done @emph{per frame}, and will evaluate to NAN
5666 when @option{eval} is set to @samp{init}.
5668 Be aware that frames are taken from each input video in timestamp
5669 order, hence, if their initial timestamps differ, it is a good idea
5670 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
5671 have them begin in the same zero timestamp, as it does the example for
5672 the @var{movie} filter.
5674 You can chain together more overlays but you should test the
5675 efficiency of such approach.
5677 @subsection Commands
5679 This filter supports the following commands:
5683 Modify the x and y of the overlay input.
5684 The command accepts the same syntax of the corresponding option.
5686 If the specified expression is not valid, it is kept at its current
5690 @subsection Examples
5694 Draw the overlay at 10 pixels from the bottom right corner of the main
5697 overlay=main_w-overlay_w-10:main_h-overlay_h-10
5700 Using named options the example above becomes:
5702 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
5706 Insert a transparent PNG logo in the bottom left corner of the input,
5707 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
5709 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
5713 Insert 2 different transparent PNG logos (second logo on bottom
5714 right corner) using the @command{ffmpeg} tool:
5716 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
5720 Add a transparent color layer on top of the main video, @code{WxH}
5721 must specify the size of the main input to the overlay filter:
5723 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
5727 Play an original video and a filtered version (here with the deshake
5728 filter) side by side using the @command{ffplay} tool:
5730 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
5733 The above command is the same as:
5735 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
5739 Make a sliding overlay appearing from the left to the right top part of the
5740 screen starting since time 2:
5742 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
5746 Compose output by putting two input videos side to side:
5748 ffmpeg -i left.avi -i right.avi -filter_complex "
5749 nullsrc=size=200x100 [background];
5750 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
5751 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
5752 [background][left] overlay=shortest=1 [background+left];
5753 [background+left][right] overlay=shortest=1:x=100 [left+right]
5758 Chain several overlays in cascade:
5760 nullsrc=s=200x200 [bg];
5761 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
5762 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
5763 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
5764 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
5765 [in3] null, [mid2] overlay=100:100 [out0]
5772 Apply Overcomplete Wavelet denoiser.
5774 The filter accepts the following options:
5780 Larger depth values will denoise lower frequency components more, but
5781 slow down filtering.
5783 Must be an int in the range 8-16, default is @code{8}.
5785 @item luma_strength, ls
5788 Must be a double value in the range 0-1000, default is @code{1.0}.
5790 @item chroma_strength, cs
5791 Set chroma strength.
5793 Must be a double value in the range 0-1000, default is @code{1.0}.
5798 Add paddings to the input image, and place the original input at the
5799 given coordinates @var{x}, @var{y}.
5801 This filter accepts the following parameters:
5806 Specify an expression for the size of the output image with the
5807 paddings added. If the value for @var{width} or @var{height} is 0, the
5808 corresponding input size is used for the output.
5810 The @var{width} expression can reference the value set by the
5811 @var{height} expression, and vice versa.
5813 The default value of @var{width} and @var{height} is 0.
5817 Specify an expression for the offsets where to place the input image
5818 in the padded area with respect to the top/left border of the output
5821 The @var{x} expression can reference the value set by the @var{y}
5822 expression, and vice versa.
5824 The default value of @var{x} and @var{y} is 0.
5827 Specify the color of the padded area, it can be the name of a color
5828 (case insensitive match) or a 0xRRGGBB[AA] sequence.
5830 The default value of @var{color} is "black".
5833 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
5834 options are expressions containing the following constants:
5839 the input video width and height
5843 same as @var{in_w} and @var{in_h}
5847 the output width and height, that is the size of the padded area as
5848 specified by the @var{width} and @var{height} expressions
5852 same as @var{out_w} and @var{out_h}
5856 x and y offsets as specified by the @var{x} and @var{y}
5857 expressions, or NAN if not yet specified
5860 same as @var{iw} / @var{ih}
5863 input sample aspect ratio
5866 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
5870 horizontal and vertical chroma subsample values. For example for the
5871 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5874 @subsection Examples
5878 Add paddings with color "violet" to the input video. Output video
5879 size is 640x480, the top-left corner of the input video is placed at
5882 pad=640:480:0:40:violet
5885 The example above is equivalent to the following command:
5887 pad=width=640:height=480:x=0:y=40:color=violet
5891 Pad the input to get an output with dimensions increased by 3/2,
5892 and put the input video at the center of the padded area:
5894 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
5898 Pad the input to get a squared output with size equal to the maximum
5899 value between the input width and height, and put the input video at
5900 the center of the padded area:
5902 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
5906 Pad the input to get a final w/h ratio of 16:9:
5908 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
5912 In case of anamorphic video, in order to set the output display aspect
5913 correctly, it is necessary to use @var{sar} in the expression,
5914 according to the relation:
5916 (ih * X / ih) * sar = output_dar
5917 X = output_dar / sar
5920 Thus the previous example needs to be modified to:
5922 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
5926 Double output size and put the input video in the bottom-right
5927 corner of the output padded area:
5929 pad="2*iw:2*ih:ow-iw:oh-ih"
5933 @section perspective
5935 Correct perspective of video not recorded perpendicular to the screen.
5937 A description of the accepted parameters follows.
5948 Set coordinates expression for top left, top right, bottom left and bottom right corners.
5949 Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
5951 The expressions can use the following variables:
5956 the width and height of video frame.
5960 Set interpolation for perspective correction.
5962 It accepts the following values:
5968 Default value is @samp{linear}.
5973 Delay interlaced video by one field time so that the field order changes.
5975 The intended use is to fix PAL movies that have been captured with the
5976 opposite field order to the film-to-video transfer.
5978 A description of the accepted parameters follows.
5984 It accepts the following values:
5987 Capture field order top-first, transfer bottom-first.
5988 Filter will delay the bottom field.
5991 Capture field order bottom-first, transfer top-first.
5992 Filter will delay the top field.
5995 Capture and transfer with the same field order. This mode only exists
5996 for the documentation of the other options to refer to, but if you
5997 actually select it, the filter will faithfully do nothing.
6000 Capture field order determined automatically by field flags, transfer
6002 Filter selects among @samp{t} and @samp{b} modes on a frame by frame
6003 basis using field flags. If no field information is available,
6004 then this works just like @samp{u}.
6007 Capture unknown or varying, transfer opposite.
6008 Filter selects among @samp{t} and @samp{b} on a frame by frame basis by
6009 analyzing the images and selecting the alternative that produces best
6010 match between the fields.
6013 Capture top-first, transfer unknown or varying.
6014 Filter selects among @samp{t} and @samp{p} using image analysis.
6017 Capture bottom-first, transfer unknown or varying.
6018 Filter selects among @samp{b} and @samp{p} using image analysis.
6021 Capture determined by field flags, transfer unknown or varying.
6022 Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and
6023 image analysis. If no field information is available, then this works just
6024 like @samp{U}. This is the default mode.
6027 Both capture and transfer unknown or varying.
6028 Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only.
6032 @section pixdesctest
6034 Pixel format descriptor test filter, mainly useful for internal
6035 testing. The output video should be equal to the input video.
6039 format=monow, pixdesctest
6042 can be used to test the monowhite pixel format descriptor definition.
6046 Enable the specified chain of postprocessing subfilters using libpostproc. This
6047 library should be automatically selected with a GPL build (@code{--enable-gpl}).
6048 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
6049 Each subfilter and some options have a short and a long name that can be used
6050 interchangeably, i.e. dr/dering are the same.
6052 The filters accept the following options:
6056 Set postprocessing subfilters string.
6059 All subfilters share common options to determine their scope:
6063 Honor the quality commands for this subfilter.
6066 Do chrominance filtering, too (default).
6069 Do luminance filtering only (no chrominance).
6072 Do chrominance filtering only (no luminance).
6075 These options can be appended after the subfilter name, separated by a '|'.
6077 Available subfilters are:
6080 @item hb/hdeblock[|difference[|flatness]]
6081 Horizontal deblocking filter
6084 Difference factor where higher values mean more deblocking (default: @code{32}).
6086 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6089 @item vb/vdeblock[|difference[|flatness]]
6090 Vertical deblocking filter
6093 Difference factor where higher values mean more deblocking (default: @code{32}).
6095 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6098 @item ha/hadeblock[|difference[|flatness]]
6099 Accurate horizontal deblocking filter
6102 Difference factor where higher values mean more deblocking (default: @code{32}).
6104 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6107 @item va/vadeblock[|difference[|flatness]]
6108 Accurate vertical deblocking filter
6111 Difference factor where higher values mean more deblocking (default: @code{32}).
6113 Flatness threshold where lower values mean more deblocking (default: @code{39}).
6117 The horizontal and vertical deblocking filters share the difference and
6118 flatness values so you cannot set different horizontal and vertical
6123 Experimental horizontal deblocking filter
6126 Experimental vertical deblocking filter
6131 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
6134 larger -> stronger filtering
6136 larger -> stronger filtering
6138 larger -> stronger filtering
6141 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
6144 Stretch luminance to @code{0-255}.
6147 @item lb/linblenddeint
6148 Linear blend deinterlacing filter that deinterlaces the given block by
6149 filtering all lines with a @code{(1 2 1)} filter.
6151 @item li/linipoldeint
6152 Linear interpolating deinterlacing filter that deinterlaces the given block by
6153 linearly interpolating every second line.
6155 @item ci/cubicipoldeint
6156 Cubic interpolating deinterlacing filter deinterlaces the given block by
6157 cubically interpolating every second line.
6159 @item md/mediandeint
6160 Median deinterlacing filter that deinterlaces the given block by applying a
6161 median filter to every second line.
6163 @item fd/ffmpegdeint
6164 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
6165 second line with a @code{(-1 4 2 4 -1)} filter.
6168 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
6169 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
6171 @item fq/forceQuant[|quantizer]
6172 Overrides the quantizer table from the input with the constant quantizer you
6180 Default pp filter combination (@code{hb|a,vb|a,dr|a})
6183 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
6186 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
6189 @subsection Examples
6193 Apply horizontal and vertical deblocking, deringing and automatic
6194 brightness/contrast:
6200 Apply default filters without brightness/contrast correction:
6206 Apply default filters and temporal denoiser:
6208 pp=default/tmpnoise|1|2|3
6212 Apply deblocking on luminance only, and switch vertical deblocking on or off
6213 automatically depending on available CPU time:
6221 Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
6222 Ratio) between two input videos.
6224 This filter takes in input two input videos, the first input is
6225 considered the "main" source and is passed unchanged to the
6226 output. The second input is used as a "reference" video for computing
6229 Both video inputs must have the same resolution and pixel format for
6230 this filter to work correctly. Also it assumes that both inputs
6231 have the same number of frames, which are compared one by one.
6233 The obtained average PSNR is printed through the logging system.
6235 The filter stores the accumulated MSE (mean squared error) of each
6236 frame, and at the end of the processing it is averaged across all frames
6237 equally, and the following formula is applied to obtain the PSNR:
6240 PSNR = 10*log10(MAX^2/MSE)
6243 Where MAX is the average of the maximum values of each component of the
6246 The description of the accepted parameters follows.
6250 If specified the filter will use the named file to save the PSNR of
6251 each individual frame.
6254 The file printed if @var{stats_file} is selected, contains a sequence of
6255 key/value pairs of the form @var{key}:@var{value} for each compared
6258 A description of each shown parameter follows:
6262 sequential number of the input frame, starting from 1
6265 Mean Square Error pixel-by-pixel average difference of the compared
6266 frames, averaged over all the image components.
6268 @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
6269 Mean Square Error pixel-by-pixel average difference of the compared
6270 frames for the component specified by the suffix.
6272 @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
6273 Peak Signal to Noise ratio of the compared frames for the component
6274 specified by the suffix.
6279 movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
6280 [main][ref] psnr="stats_file=stats.log" [out]
6283 On this example the input file being processed is compared with the
6284 reference file @file{ref_movie.mpg}. The PSNR of each individual frame
6285 is stored in @file{stats.log}.
6289 Pulldown reversal (inverse telecine) filter, capable of handling mixed
6290 hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
6293 The pullup filter is designed to take advantage of future context in making
6294 its decisions. This filter is stateless in the sense that it does not lock
6295 onto a pattern to follow, but it instead looks forward to the following
6296 fields in order to identify matches and rebuild progressive frames.
6298 To produce content with an even framerate, insert the fps filter after
6299 pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps,
6300 @code{fps=24} for 30fps and the (rare) telecined 25fps input.
6302 The filter accepts the following options:
6309 These options set the amount of "junk" to ignore at the left, right, top, and
6310 bottom of the image, respectively. Left and right are in units of 8 pixels,
6311 while top and bottom are in units of 2 lines.
6312 The default is 8 pixels on each side.
6315 Set the strict breaks. Setting this option to 1 will reduce the chances of
6316 filter generating an occasional mismatched frame, but it may also cause an
6317 excessive number of frames to be dropped during high motion sequences.
6318 Conversely, setting it to -1 will make filter match fields more easily.
6319 This may help processing of video where there is slight blurring between
6320 the fields, but may also cause there to be interlaced frames in the output.
6321 Default value is @code{0}.
6324 Set the metric plane to use. It accepts the following values:
6330 Use chroma blue plane.
6333 Use chroma red plane.
6336 This option may be set to use chroma plane instead of the default luma plane
6337 for doing filter's computations. This may improve accuracy on very clean
6338 source material, but more likely will decrease accuracy, especially if there
6339 is chroma noise (rainbow effect) or any grayscale video.
6340 The main purpose of setting @option{mp} to a chroma plane is to reduce CPU
6341 load and make pullup usable in realtime on slow machines.
6344 For example to inverse telecined NTSC input:
6346 pullup,fps=24000/1001
6351 Suppress a TV station logo, using an image file to determine which
6352 pixels comprise the logo. It works by filling in the pixels that
6353 comprise the logo with neighboring pixels.
6355 The filter accepts the following options:
6359 Set the filter bitmap file, which can be any image format supported by
6360 libavformat. The width and height of the image file must match those of the
6361 video stream being processed.
6364 Pixels in the provided bitmap image with a value of zero are not
6365 considered part of the logo, non-zero pixels are considered part of
6366 the logo. If you use white (255) for the logo and black (0) for the
6367 rest, you will be safe. For making the filter bitmap, it is
6368 recommended to take a screen capture of a black frame with the logo
6369 visible, and then using a threshold filter followed by the erode
6370 filter once or twice.
6372 If needed, little splotches can be fixed manually. Remember that if
6373 logo pixels are not covered, the filter quality will be much
6374 reduced. Marking too many pixels as part of the logo does not hurt as
6375 much, but it will increase the amount of blurring needed to cover over
6376 the image and will destroy more information than necessary, and extra
6377 pixels will slow things down on a large logo.
6381 Rotate video by an arbitrary angle expressed in radians.
6383 The filter accepts the following options:
6385 A description of the optional parameters follows.
6388 Set an expression for the angle by which to rotate the input video
6389 clockwise, expressed as a number of radians. A negative value will
6390 result in a counter-clockwise rotation. By default it is set to "0".
6392 This expression is evaluated for each frame.
6395 Set the output width expression, default value is "iw".
6396 This expression is evaluated just once during configuration.
6399 Set the output height expression, default value is "ih".
6400 This expression is evaluated just once during configuration.
6403 Enable bilinear interpolation if set to 1, a value of 0 disables
6404 it. Default value is 1.
6407 Set the color used to fill the output area not covered by the rotated
6408 image. If the special value "none" is selected then no background is
6409 printed (useful for example if the background is never shown). Default
6413 The expressions for the angle and the output size can contain the
6414 following constants and functions:
6418 sequential number of the input frame, starting from 0. It is always NAN
6419 before the first frame is filtered.
6422 time in seconds of the input frame, it is set to 0 when the filter is
6423 configured. It is always NAN before the first frame is filtered.
6427 horizontal and vertical chroma subsample values. For example for the
6428 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6432 the input video width and heigth
6436 the output width and heigth, that is the size of the padded area as
6437 specified by the @var{width} and @var{height} expressions
6441 the minimal width/height required for completely containing the input
6442 video rotated by @var{a} radians.
6444 These are only available when computing the @option{out_w} and
6445 @option{out_h} expressions.
6448 @subsection Examples
6452 Rotate the input by PI/6 radians clockwise:
6458 Rotate the input by PI/6 radians counter-clockwise:
6464 Apply a constant rotation with period T, starting from an angle of PI/3:
6466 rotate=PI/3+2*PI*t/T
6470 Make the input video rotation oscillating with a period of T
6471 seconds and an amplitude of A radians:
6473 rotate=A*sin(2*PI/T*t)
6477 Rotate the video, output size is choosen so that the whole rotating
6478 input video is always completely contained in the output:
6480 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
6484 Rotate the video, reduce the output size so that no background is ever
6487 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
6491 @subsection Commands
6493 The filter supports the following commands:
6497 Set the angle expression.
6498 The command accepts the same syntax of the corresponding option.
6500 If the specified expression is not valid, it is kept at its current
6506 Apply Shape Adaptive Blur.
6508 The filter accepts the following options:
6511 @item luma_radius, lr
6512 Set luma blur filter strength, must be a value in range 0.1-4.0, default
6513 value is 1.0. A greater value will result in a more blurred image, and
6514 in slower processing.
6516 @item luma_pre_filter_radius, lpfr
6517 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
6520 @item luma_strength, ls
6521 Set luma maximum difference between pixels to still be considered, must
6522 be a value in the 0.1-100.0 range, default value is 1.0.
6524 @item chroma_radius, cr
6525 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
6526 greater value will result in a more blurred image, and in slower
6529 @item chroma_pre_filter_radius, cpfr
6530 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
6532 @item chroma_strength, cs
6533 Set chroma maximum difference between pixels to still be considered,
6534 must be a value in the 0.1-100.0 range.
6537 Each chroma option value, if not explicitly specified, is set to the
6538 corresponding luma option value.
6542 Scale (resize) the input video, using the libswscale library.
6544 The scale filter forces the output display aspect ratio to be the same
6545 of the input, by changing the output sample aspect ratio.
6547 If the input image format is different from the format requested by
6548 the next filter, the scale filter will convert the input to the
6552 The filter accepts the following options:
6557 Set the output video dimension expression. Default value is the input
6560 If the value is 0, the input width is used for the output.
6562 If one of the values is -1, the scale filter will use a value that
6563 maintains the aspect ratio of the input image, calculated from the
6564 other specified dimension. If both of them are -1, the input size is
6567 See below for the list of accepted constants for use in the dimension
6571 Set the interlacing mode. It accepts the following values:
6575 Force interlaced aware scaling.
6578 Do not apply interlaced scaling.
6581 Select interlaced aware scaling depending on whether the source frames
6582 are flagged as interlaced or not.
6585 Default value is @samp{0}.
6588 Set libswscale scaling flags. If not explictly specified the filter
6589 applies a bilinear scaling algorithm.
6592 Set the video size, the value must be a valid abbreviation or in the
6593 form @var{width}x@var{height}.
6595 @item in_color_matrix
6596 @item out_color_matrix
6597 Set in/output YCbCr color space type.
6599 This allows the autodetected value to be overridden as well as allows forcing
6600 a specific value used for the output and encoder.
6602 If not specified, the color space type depends on the pixel format.
6608 Choose automatically.
6611 Format conforming to International Telecommunication Union (ITU)
6612 Recommendation BT.709.
6615 Set color space conforming to the United States Federal Communications
6616 Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
6619 Set color space conforming to:
6623 ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
6626 ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
6629 Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
6634 Set color space conforming to SMPTE ST 240:1999.
6639 Set in/output YCbCr sample range.
6641 This allows the autodetected value to be overridden as well as allows forcing
6642 a specific value used for the output and encoder. If not specified, the
6643 range depends on the pixel format. Possible values:
6647 Choose automatically.
6650 Set full range (0-255 in case of 8-bit luma).
6653 Set "MPEG" range (16-235 in case of 8-bit luma).
6657 Set the dithering algorithm
6661 Choose automatically.
6670 error diffusion dither
6673 @item force_original_aspect_ratio
6674 Enable decreasing or increasing output video width or height if necessary to
6675 keep the original aspect ratio. Possible values:
6679 Scale the video as specified and disable this feature.
6682 The output video dimensions will automatically be decreased if needed.
6685 The output video dimensions will automatically be increased if needed.
6689 One useful instance of this option is that when you know a specific device's
6690 maximum allowed resolution, you can use this to limit the output video to
6691 that, while retaining the aspect ratio. For example, device A allows
6692 1280x720 playback, and your video is 1920x800. Using this option (set it to
6693 decrease) and specifying 1280x720 to the command line makes the output
6696 Please note that this is a different thing than specifying -1 for @option{w}
6697 or @option{h}, you still need to specify the output resolution for this option
6702 The values of the @option{w} and @option{h} options are expressions
6703 containing the following constants:
6708 the input width and height
6712 same as @var{in_w} and @var{in_h}
6716 the output (scaled) width and height
6720 same as @var{out_w} and @var{out_h}
6723 same as @var{iw} / @var{ih}
6726 input sample aspect ratio
6729 input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
6733 horizontal and vertical chroma subsample values. For example for the
6734 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6737 @subsection Examples
6741 Scale the input video to a size of 200x100:
6746 This is equivalent to:
6757 Specify a size abbreviation for the output size:
6762 which can also be written as:
6768 Scale the input to 2x:
6774 The above is the same as:
6780 Scale the input to 2x with forced interlaced scaling:
6782 scale=2*iw:2*ih:interl=1
6786 Scale the input to half size:
6792 Increase the width, and set the height to the same size:
6798 Seek for Greek harmony:
6805 Increase the height, and set the width to 3/2 of the height:
6807 scale=w=3/2*oh:h=3/5*ih
6811 Increase the size, but make the size a multiple of the chroma
6814 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
6818 Increase the width to a maximum of 500 pixels, keep the same input
6821 scale=w='min(500\, iw*3/2):h=-1'
6825 @section separatefields
6827 The @code{separatefields} takes a frame-based video input and splits
6828 each frame into its components fields, producing a new half height clip
6829 with twice the frame rate and twice the frame count.
6831 This filter use field-dominance information in frame to decide which
6832 of each pair of fields to place first in the output.
6833 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
6835 @section setdar, setsar
6837 The @code{setdar} filter sets the Display Aspect Ratio for the filter
6840 This is done by changing the specified Sample (aka Pixel) Aspect
6841 Ratio, according to the following equation:
6843 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
6846 Keep in mind that the @code{setdar} filter does not modify the pixel
6847 dimensions of the video frame. Also the display aspect ratio set by
6848 this filter may be changed by later filters in the filterchain,
6849 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
6852 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
6853 the filter output video.
6855 Note that as a consequence of the application of this filter, the
6856 output display aspect ratio will change according to the equation
6859 Keep in mind that the sample aspect ratio set by the @code{setsar}
6860 filter may be changed by later filters in the filterchain, e.g. if
6861 another "setsar" or a "setdar" filter is applied.
6863 The filters accept the following options:
6866 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
6867 Set the aspect ratio used by the filter.
6869 The parameter can be a floating point number string, an expression, or
6870 a string of the form @var{num}:@var{den}, where @var{num} and
6871 @var{den} are the numerator and denominator of the aspect ratio. If
6872 the parameter is not specified, it is assumed the value "0".
6873 In case the form "@var{num}:@var{den}" is used, the @code{:} character
6877 Set the maximum integer value to use for expressing numerator and
6878 denominator when reducing the expressed aspect ratio to a rational.
6879 Default value is @code{100}.
6883 @subsection Examples
6888 To change the display aspect ratio to 16:9, specify one of the following:
6896 To change the sample aspect ratio to 10:11, specify:
6902 To set a display aspect ratio of 16:9, and specify a maximum integer value of
6903 1000 in the aspect ratio reduction, use the command:
6905 setdar=ratio=16/9:max=1000
6913 Force field for the output video frame.
6915 The @code{setfield} filter marks the interlace type field for the
6916 output frames. It does not change the input frame, but only sets the
6917 corresponding property, which affects how the frame is treated by
6918 following filters (e.g. @code{fieldorder} or @code{yadif}).
6920 The filter accepts the following options:
6925 Available values are:
6929 Keep the same field property.
6932 Mark the frame as bottom-field-first.
6935 Mark the frame as top-field-first.
6938 Mark the frame as progressive.
6944 Show a line containing various information for each input video frame.
6945 The input video is not modified.
6947 The shown line contains a sequence of key/value pairs of the form
6948 @var{key}:@var{value}.
6950 A description of each shown parameter follows:
6954 sequential number of the input frame, starting from 0
6957 Presentation TimeStamp of the input frame, expressed as a number of
6958 time base units. The time base unit depends on the filter input pad.
6961 Presentation TimeStamp of the input frame, expressed as a number of
6965 position of the frame in the input stream, -1 if this information in
6966 unavailable and/or meaningless (for example in case of synthetic video)
6972 sample aspect ratio of the input frame, expressed in the form
6976 size of the input frame, expressed in the form
6977 @var{width}x@var{height}
6980 interlaced mode ("P" for "progressive", "T" for top field first, "B"
6981 for bottom field first)
6984 1 if the frame is a key frame, 0 otherwise
6987 picture type of the input frame ("I" for an I-frame, "P" for a
6988 P-frame, "B" for a B-frame, "?" for unknown type).
6989 Check also the documentation of the @code{AVPictureType} enum and of
6990 the @code{av_get_picture_type_char} function defined in
6991 @file{libavutil/avutil.h}.
6994 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
6996 @item plane_checksum
6997 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
6998 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
7004 Blur the input video without impacting the outlines.
7006 The filter accepts the following options:
7009 @item luma_radius, lr
7010 Set the luma radius. The option value must be a float number in
7011 the range [0.1,5.0] that specifies the variance of the gaussian filter
7012 used to blur the image (slower if larger). Default value is 1.0.
7014 @item luma_strength, ls
7015 Set the luma strength. The option value must be a float number
7016 in the range [-1.0,1.0] that configures the blurring. A value included
7017 in [0.0,1.0] will blur the image whereas a value included in
7018 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7020 @item luma_threshold, lt
7021 Set the luma threshold used as a coefficient to determine
7022 whether a pixel should be blurred or not. The option value must be an
7023 integer in the range [-30,30]. A value of 0 will filter all the image,
7024 a value included in [0,30] will filter flat areas and a value included
7025 in [-30,0] will filter edges. Default value is 0.
7027 @item chroma_radius, cr
7028 Set the chroma radius. The option value must be a float number in
7029 the range [0.1,5.0] that specifies the variance of the gaussian filter
7030 used to blur the image (slower if larger). Default value is 1.0.
7032 @item chroma_strength, cs
7033 Set the chroma strength. The option value must be a float number
7034 in the range [-1.0,1.0] that configures the blurring. A value included
7035 in [0.0,1.0] will blur the image whereas a value included in
7036 [-1.0,0.0] will sharpen the image. Default value is 1.0.
7038 @item chroma_threshold, ct
7039 Set the chroma threshold used as a coefficient to determine
7040 whether a pixel should be blurred or not. The option value must be an
7041 integer in the range [-30,30]. A value of 0 will filter all the image,
7042 a value included in [0,30] will filter flat areas and a value included
7043 in [-30,0] will filter edges. Default value is 0.
7046 If a chroma option is not explicitly set, the corresponding luma value
7051 Convert between different stereoscopic image formats.
7053 The filters accept the following options:
7057 Set stereoscopic image format of input.
7059 Available values for input image formats are:
7062 side by side parallel (left eye left, right eye right)
7065 side by side crosseye (right eye left, left eye right)
7068 side by side parallel with half width resolution
7069 (left eye left, right eye right)
7072 side by side crosseye with half width resolution
7073 (right eye left, left eye right)
7076 above-below (left eye above, right eye below)
7079 above-below (right eye above, left eye below)
7082 above-below with half height resolution
7083 (left eye above, right eye below)
7086 above-below with half height resolution
7087 (right eye above, left eye below)
7090 alternating frames (left eye first, right eye second)
7093 alternating frames (right eye first, left eye second)
7095 Default value is @samp{sbsl}.
7099 Set stereoscopic image format of output.
7101 Available values for output image formats are all the input formats as well as:
7104 anaglyph red/blue gray
7105 (red filter on left eye, blue filter on right eye)
7108 anaglyph red/green gray
7109 (red filter on left eye, green filter on right eye)
7112 anaglyph red/cyan gray
7113 (red filter on left eye, cyan filter on right eye)
7116 anaglyph red/cyan half colored
7117 (red filter on left eye, cyan filter on right eye)
7120 anaglyph red/cyan color
7121 (red filter on left eye, cyan filter on right eye)
7124 anaglyph red/cyan color optimized with the least squares projection of dubois
7125 (red filter on left eye, cyan filter on right eye)
7128 anaglyph green/magenta gray
7129 (green filter on left eye, magenta filter on right eye)
7132 anaglyph green/magenta half colored
7133 (green filter on left eye, magenta filter on right eye)
7136 anaglyph green/magenta colored
7137 (green filter on left eye, magenta filter on right eye)
7140 anaglyph green/magenta color optimized with the least squares projection of dubois
7141 (green filter on left eye, magenta filter on right eye)
7144 anaglyph yellow/blue gray
7145 (yellow filter on left eye, blue filter on right eye)
7148 anaglyph yellow/blue half colored
7149 (yellow filter on left eye, blue filter on right eye)
7152 anaglyph yellow/blue colored
7153 (yellow filter on left eye, blue filter on right eye)
7156 anaglyph yellow/blue color optimized with the least squares projection of dubois
7157 (yellow filter on left eye, blue filter on right eye)
7160 interleaved rows (left eye has top row, right eye starts on next row)
7163 interleaved rows (right eye has top row, left eye starts on next row)
7166 mono output (left eye only)
7169 mono output (right eye only)
7172 Default value is @samp{arcd}.
7175 @subsection Examples
7179 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
7185 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
7193 Apply a simple postprocessing filter that compresses and decompresses the image
7194 at several (or - in the case of @option{quality} level @code{6} - all) shifts
7195 and average the results.
7197 The filter accepts the following options:
7201 Set quality. This option defines the number of levels for averaging. It accepts
7202 an integer in the range 0-6. If set to @code{0}, the filter will have no
7203 effect. A value of @code{6} means the higher quality. For each increment of
7204 that value the speed drops by a factor of approximately 2. Default value is
7208 Force a constant quantization parameter. If not set, the filter will use the QP
7209 from the video stream (if available).
7212 Set thresholding mode. Available modes are:
7216 Set hard thresholding (default).
7218 Set soft thresholding (better de-ringing effect, but likely blurrier).
7222 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
7223 option may cause flicker since the B-Frames have often larger QP. Default is
7224 @code{0} (not enabled).
7230 Draw subtitles on top of input video using the libass library.
7232 To enable compilation of this filter you need to configure FFmpeg with
7233 @code{--enable-libass}. This filter also requires a build with libavcodec and
7234 libavformat to convert the passed subtitles file to ASS (Advanced Substation
7235 Alpha) subtitles format.
7237 The filter accepts the following options:
7241 Set the filename of the subtitle file to read. It must be specified.
7244 Specify the size of the original video, the video for which the ASS file
7245 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
7246 necessary to correctly scale the fonts if the aspect ratio has been changed.
7249 Set subtitles input character encoding. @code{subtitles} filter only. Only
7250 useful if not UTF-8.
7253 If the first key is not specified, it is assumed that the first value
7254 specifies the @option{filename}.
7256 For example, to render the file @file{sub.srt} on top of the input
7257 video, use the command:
7262 which is equivalent to:
7264 subtitles=filename=sub.srt
7269 Scale the input by 2x and smooth using the Super2xSaI (Scale and
7270 Interpolate) pixel art scaling algorithm.
7272 Useful for enlarging pixel art images without reducing sharpness.
7279 Apply telecine process to the video.
7281 This filter accepts the following options:
7290 The default value is @code{top}.
7294 A string of numbers representing the pulldown pattern you wish to apply.
7295 The default value is @code{23}.
7299 Some typical patterns:
7304 24p: 2332 (preferred)
7311 24p: 222222222223 ("Euro pulldown")
7317 Select the most representative frame in a given sequence of consecutive frames.
7319 The filter accepts the following options:
7323 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
7324 will pick one of them, and then handle the next batch of @var{n} frames until
7325 the end. Default is @code{100}.
7328 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
7329 value will result in a higher memory usage, so a high value is not recommended.
7331 @subsection Examples
7335 Extract one picture each 50 frames:
7341 Complete example of a thumbnail creation with @command{ffmpeg}:
7343 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
7349 Tile several successive frames together.
7351 The filter accepts the following options:
7356 Set the grid size (i.e. the number of lines and columns) in the form
7360 Set the maximum number of frames to render in the given area. It must be less
7361 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
7362 the area will be used.
7365 Set the outer border margin in pixels.
7368 Set the inner border thickness (i.e. the number of pixels between frames). For
7369 more advanced padding options (such as having different values for the edges),
7370 refer to the pad video filter.
7373 Specify the color of the unused area, it can be the name of a color
7374 (case insensitive match) or a 0xRRGGBB[AA] sequence.
7375 The default value of @var{color} is "black".
7378 @subsection Examples
7382 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
7384 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
7386 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
7387 duplicating each output frame to accomodate the originally detected frame
7391 Display @code{5} pictures in an area of @code{3x2} frames,
7392 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
7393 mixed flat and named options:
7395 tile=3x2:nb_frames=5:padding=7:margin=2
7401 Perform various types of temporal field interlacing.
7403 Frames are counted starting from 1, so the first input frame is
7406 The filter accepts the following options:
7411 Specify the mode of the interlacing. This option can also be specified
7412 as a value alone. See below for a list of values for this option.
7414 Available values are:
7418 Move odd frames into the upper field, even into the lower field,
7419 generating a double height frame at half frame rate.
7422 Only output even frames, odd frames are dropped, generating a frame with
7423 unchanged height at half frame rate.
7426 Only output odd frames, even frames are dropped, generating a frame with
7427 unchanged height at half frame rate.
7430 Expand each frame to full height, but pad alternate lines with black,
7431 generating a frame with double height at the same input frame rate.
7433 @item interleave_top, 4
7434 Interleave the upper field from odd frames with the lower field from
7435 even frames, generating a frame with unchanged height at half frame rate.
7437 @item interleave_bottom, 5
7438 Interleave the lower field from odd frames with the upper field from
7439 even frames, generating a frame with unchanged height at half frame rate.
7441 @item interlacex2, 6
7442 Double frame rate with unchanged height. Frames are inserted each
7443 containing the second temporal field from the previous input frame and
7444 the first temporal field from the next input frame. This mode relies on
7445 the top_field_first flag. Useful for interlaced video displays with no
7446 field synchronisation.
7449 Numeric values are deprecated but are accepted for backward
7450 compatibility reasons.
7452 Default mode is @code{merge}.
7455 Specify flags influencing the filter process.
7457 Available value for @var{flags} is:
7460 @item low_pass_filter, vlfp
7461 Enable vertical low-pass filtering in the filter.
7462 Vertical low-pass filtering is required when creating an interlaced
7463 destination from a progressive source which contains high-frequency
7464 vertical detail. Filtering will reduce interlace 'twitter' and Moire
7467 Vertical low-pass filtering can only be enabled for @option{mode}
7468 @var{interleave_top} and @var{interleave_bottom}.
7475 Transpose rows with columns in the input video and optionally flip it.
7477 This filter accepts the following options:
7482 Specify the transposition direction.
7484 Can assume the following values:
7486 @item 0, 4, cclock_flip
7487 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
7495 Rotate by 90 degrees clockwise, that is:
7503 Rotate by 90 degrees counterclockwise, that is:
7510 @item 3, 7, clock_flip
7511 Rotate by 90 degrees clockwise and vertically flip, that is:
7519 For values between 4-7, the transposition is only done if the input
7520 video geometry is portrait and not landscape. These values are
7521 deprecated, the @code{passthrough} option should be used instead.
7523 Numerical values are deprecated, and should be dropped in favor of
7527 Do not apply the transposition if the input geometry matches the one
7528 specified by the specified value. It accepts the following values:
7531 Always apply transposition.
7533 Preserve portrait geometry (when @var{height} >= @var{width}).
7535 Preserve landscape geometry (when @var{width} >= @var{height}).
7538 Default value is @code{none}.
7541 For example to rotate by 90 degrees clockwise and preserve portrait
7544 transpose=dir=1:passthrough=portrait
7547 The command above can also be specified as:
7549 transpose=1:portrait
7553 Trim the input so that the output contains one continuous subpart of the input.
7555 This filter accepts the following options:
7558 Specify time of the start of the kept section, i.e. the frame with the
7559 timestamp @var{start} will be the first frame in the output.
7562 Specify time of the first frame that will be dropped, i.e. the frame
7563 immediately preceding the one with the timestamp @var{end} will be the last
7564 frame in the output.
7567 Same as @var{start}, except this option sets the start timestamp in timebase
7568 units instead of seconds.
7571 Same as @var{end}, except this option sets the end timestamp in timebase units
7575 Specify maximum duration of the output.
7578 Number of the first frame that should be passed to output.
7581 Number of the first frame that should be dropped.
7584 @option{start}, @option{end}, @option{duration} are expressed as time
7585 duration specifications, check the "Time duration" section in the
7586 ffmpeg-utils manual.
7588 Note that the first two sets of the start/end options and the @option{duration}
7589 option look at the frame timestamp, while the _frame variants simply count the
7590 frames that pass through the filter. Also note that this filter does not modify
7591 the timestamps. If you wish that the output timestamps start at zero, insert a
7592 setpts filter after the trim filter.
7594 If multiple start or end options are set, this filter tries to be greedy and
7595 keep all the frames that match at least one of the specified constraints. To keep
7596 only the part that matches all the constraints at once, chain multiple trim
7599 The defaults are such that all the input is kept. So it is possible to set e.g.
7600 just the end values to keep everything before the specified time.
7605 drop everything except the second minute of input
7607 ffmpeg -i INPUT -vf trim=60:120
7611 keep only the first second
7613 ffmpeg -i INPUT -vf trim=duration=1
7621 Sharpen or blur the input video.
7623 It accepts the following parameters:
7626 @item luma_msize_x, lx
7627 Set the luma matrix horizontal size. It must be an odd integer between
7628 3 and 63, default value is 5.
7630 @item luma_msize_y, ly
7631 Set the luma matrix vertical size. It must be an odd integer between 3
7632 and 63, default value is 5.
7634 @item luma_amount, la
7635 Set the luma effect strength. It can be a float number, reasonable
7636 values lay between -1.5 and 1.5.
7638 Negative values will blur the input video, while positive values will
7639 sharpen it, a value of zero will disable the effect.
7641 Default value is 1.0.
7643 @item chroma_msize_x, cx
7644 Set the chroma matrix horizontal size. It must be an odd integer
7645 between 3 and 63, default value is 5.
7647 @item chroma_msize_y, cy
7648 Set the chroma matrix vertical size. It must be an odd integer
7649 between 3 and 63, default value is 5.
7651 @item chroma_amount, ca
7652 Set the chroma effect strength. It can be a float number, reasonable
7653 values lay between -1.5 and 1.5.
7655 Negative values will blur the input video, while positive values will
7656 sharpen it, a value of zero will disable the effect.
7658 Default value is 0.0.
7661 If set to 1, specify using OpenCL capabilities, only available if
7662 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
7666 All parameters are optional and default to the equivalent of the
7667 string '5:5:1.0:5:5:0.0'.
7669 @subsection Examples
7673 Apply strong luma sharpen effect:
7675 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
7679 Apply strong blur of both luma and chroma parameters:
7681 unsharp=7:7:-2:7:7:-2
7685 @anchor{vidstabdetect}
7686 @section vidstabdetect
7688 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
7689 @ref{vidstabtransform} for pass 2.
7691 This filter generates a file with relative translation and rotation
7692 transform information about subsequent frames, which is then used by
7693 the @ref{vidstabtransform} filter.
7695 To enable compilation of this filter you need to configure FFmpeg with
7696 @code{--enable-libvidstab}.
7698 This filter accepts the following options:
7702 Set the path to the file used to write the transforms information.
7703 Default value is @file{transforms.trf}.
7706 Set how shaky the video is and how quick the camera is. It accepts an
7707 integer in the range 1-10, a value of 1 means little shakiness, a
7708 value of 10 means strong shakiness. Default value is 5.
7711 Set the accuracy of the detection process. It must be a value in the
7712 range 1-15. A value of 1 means low accuracy, a value of 15 means high
7713 accuracy. Default value is 9.
7716 Set stepsize of the search process. The region around minimum is
7717 scanned with 1 pixel resolution. Default value is 6.
7720 Set minimum contrast. Below this value a local measurement field is
7721 discarded. Must be a floating point value in the range 0-1. Default
7725 Set reference frame number for tripod mode.
7727 If enabled, the motion of the frames is compared to a reference frame
7728 in the filtered stream, identified by the specified number. The idea
7729 is to compensate all movements in a more-or-less static scene and keep
7730 the camera view absolutely still.
7732 If set to 0, it is disabled. The frames are counted starting from 1.
7735 Show fields and transforms in the resulting frames. It accepts an
7736 integer in the range 0-2. Default value is 0, which disables any
7740 @subsection Examples
7750 Analyze strongly shaky movie and put the results in file
7751 @file{mytransforms.trf}:
7753 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
7757 Visualize the result of internal transformations in the resulting
7760 vidstabdetect=show=1
7764 Analyze a video with medium shakiness using @command{ffmpeg}:
7766 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
7770 @anchor{vidstabtransform}
7771 @section vidstabtransform
7773 Video stabilization/deshaking: pass 2 of 2,
7774 see @ref{vidstabdetect} for pass 1.
7776 Read a file with transform information for each frame and
7777 apply/compensate them. Together with the @ref{vidstabdetect}
7778 filter this can be used to deshake videos. See also
7779 @url{http://public.hronopik.de/vid.stab}. It is important to also use
7780 the unsharp filter, see below.
7782 To enable compilation of this filter you need to configure FFmpeg with
7783 @code{--enable-libvidstab}.
7785 This filter accepts the following options:
7790 path to the file used to read the transforms (default: @file{transforms.trf})
7793 number of frames (value*2 + 1) used for lowpass filtering the camera movements
7794 (default: 10). For example a number of 10 means that 21 frames are used
7795 (10 in the past and 10 in the future) to smoothen the motion in the
7796 video. A larger values leads to a smoother video, but limits the
7797 acceleration of the camera (pan/tilt movements).
7800 maximal number of pixels to translate frames (default: -1 no limit)
7803 maximal angle in radians (degree*PI/180) to rotate frames (default: -1
7807 How to deal with borders that may be visible due to movement
7808 compensation. Available values are:
7812 keep image information from previous frame (default)
7814 fill the border black
7820 keep transforms normal (default)
7827 consider transforms as
7832 relative to previous frame (default)
7837 percentage to zoom (default: 0)
7846 if 1 then optimal zoom value is determined (default).
7847 Optimal zoom means no (or only little) border should be visible.
7848 Note that the value given at zoom is added to the one calculated
7852 type of interpolation
7854 Available values are:
7859 linear only horizontal
7861 linear in both directions (default)
7863 cubic in both directions (slow)
7867 virtual tripod mode means that the video is stabilized such that the
7868 camera stays stationary. Use also @code{tripod} option of
7869 @ref{vidstabdetect}.
7874 virtual tripod mode: equivalent to @code{relative=0:smoothing=0}
7879 @subsection Examples
7883 typical call with default default values:
7884 (note the unsharp filter which is always recommended)
7886 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
7890 zoom in a bit more and load transform data from a given file
7892 vidstabtransform=zoom=5:input="mytransforms.trf"
7896 smoothen the video even more
7898 vidstabtransform=smoothing=30
7905 Flip the input video vertically.
7907 For example, to vertically flip a video with @command{ffmpeg}:
7909 ffmpeg -i in.avi -vf "vflip" out.avi
7914 Make or reverse a natural vignetting effect.
7916 The filter accepts the following options:
7920 Set lens angle expression as a number of radians.
7922 The value is clipped in the @code{[0,PI/2]} range.
7924 Default value: @code{"PI/5"}
7928 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
7932 Set forward/backward mode.
7934 Available modes are:
7937 The larger the distance from the central point, the darker the image becomes.
7940 The larger the distance from the central point, the brighter the image becomes.
7941 This can be used to reverse a vignette effect, though there is no automatic
7942 detection to extract the lens @option{angle} and other settings (yet). It can
7943 also be used to create a burning effect.
7946 Default value is @samp{forward}.
7949 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
7951 It accepts the following values:
7954 Evaluate expressions only once during the filter initialization.
7957 Evaluate expressions for each incoming frame. This is way slower than the
7958 @samp{init} mode since it requires all the scalers to be re-computed, but it
7959 allows advanced dynamic expressions.
7962 Default value is @samp{init}.
7965 Set dithering to reduce the circular banding effects. Default is @code{1}
7969 Set vignette aspect. This setting allows to adjust the shape of the vignette.
7970 Setting this value to the SAR of the input will make a rectangular vignetting
7971 following the dimensions of the video.
7973 Default is @code{1/1}.
7976 @subsection Expressions
7978 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
7979 following parameters.
7984 input width and height
7987 the number of input frame, starting from 0
7990 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
7991 @var{TB} units, NAN if undefined
7994 frame rate of the input video, NAN if the input frame rate is unknown
7997 the PTS (Presentation TimeStamp) of the filtered video frame,
7998 expressed in seconds, NAN if undefined
8001 time base of the input video
8005 @subsection Examples
8009 Apply simple strong vignetting effect:
8015 Make a flickering vignetting:
8017 vignette='PI/4+random(1)*PI/50':eval=frame
8024 Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
8025 Deinterlacing Filter").
8027 Based on the process described by Martin Weston for BBC R&D, and
8028 implemented based on the de-interlace algorithm written by Jim
8029 Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
8030 uses filter coefficients calculated by BBC R&D.
8032 There are two sets of filter coefficients, so called "simple":
8033 and "complex". Which set of filter coefficients is used can
8034 be set by passing an optional parameter:
8038 Set the interlacing filter coefficients. Accepts one of the following values:
8042 Simple filter coefficient set.
8044 More-complex filter coefficient set.
8046 Default value is @samp{complex}.
8049 Specify which frames to deinterlace. Accept one of the following values:
8053 Deinterlace all frames,
8055 Only deinterlace frames marked as interlaced.
8058 Default value is @samp{all}.
8064 Deinterlace the input video ("yadif" means "yet another deinterlacing
8067 This filter accepts the following options:
8073 The interlacing mode to adopt, accepts one of the following values:
8077 output 1 frame for each frame
8079 output 1 frame for each field
8080 @item 2, send_frame_nospatial
8081 like @code{send_frame} but skip spatial interlacing check
8082 @item 3, send_field_nospatial
8083 like @code{send_field} but skip spatial interlacing check
8086 Default value is @code{send_frame}.
8089 The picture field parity assumed for the input interlaced video, accepts one of
8090 the following values:
8094 assume top field first
8096 assume bottom field first
8098 enable automatic detection
8101 Default value is @code{auto}.
8102 If interlacing is unknown or decoder does not export this information,
8103 top field first will be assumed.
8106 Specify which frames to deinterlace. Accept one of the following
8111 deinterlace all frames
8113 only deinterlace frames marked as interlaced
8116 Default value is @code{all}.
8119 @c man end VIDEO FILTERS
8121 @chapter Video Sources
8122 @c man begin VIDEO SOURCES
8124 Below is a description of the currently available video sources.
8128 Buffer video frames, and make them available to the filter chain.
8130 This source is mainly intended for a programmatic use, in particular
8131 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
8133 This source accepts the following options:
8138 Specify the size (width and height) of the buffered video frames.
8147 A string representing the pixel format of the buffered video frames.
8148 It may be a number corresponding to a pixel format, or a pixel format
8152 Specify the timebase assumed by the timestamps of the buffered frames.
8155 Specify the frame rate expected for the video stream.
8157 @item pixel_aspect, sar
8158 Specify the sample aspect ratio assumed by the video frames.
8161 Specify the optional parameters to be used for the scale filter which
8162 is automatically inserted when an input change is detected in the
8163 input size or format.
8168 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
8171 will instruct the source to accept video frames with size 320x240 and
8172 with format "yuv410p", assuming 1/24 as the timestamps timebase and
8173 square pixels (1:1 sample aspect ratio).
8174 Since the pixel format with name "yuv410p" corresponds to the number 6
8175 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
8176 this example corresponds to:
8178 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
8181 Alternatively, the options can be specified as a flat string, but this
8182 syntax is deprecated:
8184 @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}]
8188 Create a pattern generated by an elementary cellular automaton.
8190 The initial state of the cellular automaton can be defined through the
8191 @option{filename}, and @option{pattern} options. If such options are
8192 not specified an initial state is created randomly.
8194 At each new frame a new row in the video is filled with the result of
8195 the cellular automaton next generation. The behavior when the whole
8196 frame is filled is defined by the @option{scroll} option.
8198 This source accepts the following options:
8202 Read the initial cellular automaton state, i.e. the starting row, from
8204 In the file, each non-whitespace character is considered an alive
8205 cell, a newline will terminate the row, and further characters in the
8206 file will be ignored.
8209 Read the initial cellular automaton state, i.e. the starting row, from
8210 the specified string.
8212 Each non-whitespace character in the string is considered an alive
8213 cell, a newline will terminate the row, and further characters in the
8214 string will be ignored.
8217 Set the video rate, that is the number of frames generated per second.
8220 @item random_fill_ratio, ratio
8221 Set the random fill ratio for the initial cellular automaton row. It
8222 is a floating point number value ranging from 0 to 1, defaults to
8225 This option is ignored when a file or a pattern is specified.
8227 @item random_seed, seed
8228 Set the seed for filling randomly the initial row, must be an integer
8229 included between 0 and UINT32_MAX. If not specified, or if explicitly
8230 set to -1, the filter will try to use a good random seed on a best
8234 Set the cellular automaton rule, it is a number ranging from 0 to 255.
8235 Default value is 110.
8238 Set the size of the output video.
8240 If @option{filename} or @option{pattern} is specified, the size is set
8241 by default to the width of the specified initial state row, and the
8242 height is set to @var{width} * PHI.
8244 If @option{size} is set, it must contain the width of the specified
8245 pattern string, and the specified pattern will be centered in the
8248 If a filename or a pattern string is not specified, the size value
8249 defaults to "320x518" (used for a randomly generated initial state).
8252 If set to 1, scroll the output upward when all the rows in the output
8253 have been already filled. If set to 0, the new generated row will be
8254 written over the top row just after the bottom row is filled.
8257 @item start_full, full
8258 If set to 1, completely fill the output with generated rows before
8259 outputting the first frame.
8260 This is the default behavior, for disabling set the value to 0.
8263 If set to 1, stitch the left and right row edges together.
8264 This is the default behavior, for disabling set the value to 0.
8267 @subsection Examples
8271 Read the initial state from @file{pattern}, and specify an output of
8274 cellauto=f=pattern:s=200x400
8278 Generate a random initial row with a width of 200 cells, with a fill
8281 cellauto=ratio=2/3:s=200x200
8285 Create a pattern generated by rule 18 starting by a single alive cell
8286 centered on an initial row with width 100:
8288 cellauto=p=@@:s=100x400:full=0:rule=18
8292 Specify a more elaborated initial pattern:
8294 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
8301 Generate a Mandelbrot set fractal, and progressively zoom towards the
8302 point specified with @var{start_x} and @var{start_y}.
8304 This source accepts the following options:
8309 Set the terminal pts value. Default value is 400.
8312 Set the terminal scale value.
8313 Must be a floating point value. Default value is 0.3.
8316 Set the inner coloring mode, that is the algorithm used to draw the
8317 Mandelbrot fractal internal region.
8319 It shall assume one of the following values:
8324 Show time until convergence.
8326 Set color based on point closest to the origin of the iterations.
8331 Default value is @var{mincol}.
8334 Set the bailout value. Default value is 10.0.
8337 Set the maximum of iterations performed by the rendering
8338 algorithm. Default value is 7189.
8341 Set outer coloring mode.
8342 It shall assume one of following values:
8344 @item iteration_count
8345 Set iteration cound mode.
8346 @item normalized_iteration_count
8347 set normalized iteration count mode.
8349 Default value is @var{normalized_iteration_count}.
8352 Set frame rate, expressed as number of frames per second. Default
8356 Set frame size. Default value is "640x480".
8359 Set the initial scale value. Default value is 3.0.
8362 Set the initial x position. Must be a floating point value between
8363 -100 and 100. Default value is -0.743643887037158704752191506114774.
8366 Set the initial y position. Must be a floating point value between
8367 -100 and 100. Default value is -0.131825904205311970493132056385139.
8372 Generate various test patterns, as generated by the MPlayer test filter.
8374 The size of the generated video is fixed, and is 256x256.
8375 This source is useful in particular for testing encoding features.
8377 This source accepts the following options:
8382 Specify the frame rate of the sourced video, as the number of frames
8383 generated per second. It has to be a string in the format
8384 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
8385 number or a valid video frame rate abbreviation. The default value is
8389 Set the video duration of the sourced video. The accepted syntax is:
8394 See also the function @code{av_parse_time()}.
8396 If not specified, or the expressed duration is negative, the video is
8397 supposed to be generated forever.
8401 Set the number or the name of the test to perform. Supported tests are:
8416 Default value is "all", which will cycle through the list of all tests.
8419 For example the following:
8424 will generate a "dc_luma" test pattern.
8428 Provide a frei0r source.
8430 To enable compilation of this filter you need to install the frei0r
8431 header and configure FFmpeg with @code{--enable-frei0r}.
8433 This source accepts the following options:
8438 The size of the video to generate, may be a string of the form
8439 @var{width}x@var{height} or a frame size abbreviation.
8442 Framerate of the generated video, may be a string of the form
8443 @var{num}/@var{den} or a frame rate abbreviation.
8446 The name to the frei0r source to load. For more information regarding frei0r and
8447 how to set the parameters read the section @ref{frei0r} in the description of
8451 A '|'-separated list of parameters to pass to the frei0r source.
8455 For example, to generate a frei0r partik0l source with size 200x200
8456 and frame rate 10 which is overlayed on the overlay filter main input:
8458 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
8463 Generate a life pattern.
8465 This source is based on a generalization of John Conway's life game.
8467 The sourced input represents a life grid, each pixel represents a cell
8468 which can be in one of two possible states, alive or dead. Every cell
8469 interacts with its eight neighbours, which are the cells that are
8470 horizontally, vertically, or diagonally adjacent.
8472 At each interaction the grid evolves according to the adopted rule,
8473 which specifies the number of neighbor alive cells which will make a
8474 cell stay alive or born. The @option{rule} option allows to specify
8477 This source accepts the following options:
8481 Set the file from which to read the initial grid state. In the file,
8482 each non-whitespace character is considered an alive cell, and newline
8483 is used to delimit the end of each row.
8485 If this option is not specified, the initial grid is generated
8489 Set the video rate, that is the number of frames generated per second.
8492 @item random_fill_ratio, ratio
8493 Set the random fill ratio for the initial random grid. It is a
8494 floating point number value ranging from 0 to 1, defaults to 1/PHI.
8495 It is ignored when a file is specified.
8497 @item random_seed, seed
8498 Set the seed for filling the initial random grid, must be an integer
8499 included between 0 and UINT32_MAX. If not specified, or if explicitly
8500 set to -1, the filter will try to use a good random seed on a best
8506 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
8507 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
8508 @var{NS} specifies the number of alive neighbor cells which make a
8509 live cell stay alive, and @var{NB} the number of alive neighbor cells
8510 which make a dead cell to become alive (i.e. to "born").
8511 "s" and "b" can be used in place of "S" and "B", respectively.
8513 Alternatively a rule can be specified by an 18-bits integer. The 9
8514 high order bits are used to encode the next cell state if it is alive
8515 for each number of neighbor alive cells, the low order bits specify
8516 the rule for "borning" new cells. Higher order bits encode for an
8517 higher number of neighbor cells.
8518 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
8519 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
8521 Default value is "S23/B3", which is the original Conway's game of life
8522 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
8523 cells, and will born a new cell if there are three alive cells around
8527 Set the size of the output video.
8529 If @option{filename} is specified, the size is set by default to the
8530 same size of the input file. If @option{size} is set, it must contain
8531 the size specified in the input file, and the initial grid defined in
8532 that file is centered in the larger resulting area.
8534 If a filename is not specified, the size value defaults to "320x240"
8535 (used for a randomly generated initial grid).
8538 If set to 1, stitch the left and right grid edges together, and the
8539 top and bottom edges also. Defaults to 1.
8542 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
8543 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
8544 value from 0 to 255.
8547 Set the color of living (or new born) cells.
8550 Set the color of dead cells. If @option{mold} is set, this is the first color
8551 used to represent a dead cell.
8554 Set mold color, for definitely dead and moldy cells.
8557 @subsection Examples
8561 Read a grid from @file{pattern}, and center it on a grid of size
8564 life=f=pattern:s=300x300
8568 Generate a random grid of size 200x200, with a fill ratio of 2/3:
8570 life=ratio=2/3:s=200x200
8574 Specify a custom rule for evolving a randomly generated grid:
8580 Full example with slow death effect (mold) using @command{ffplay}:
8582 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
8587 @anchor{haldclutsrc}
8591 @anchor{smptehdbars}
8593 @section color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
8595 The @code{color} source provides an uniformly colored input.
8597 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
8598 @ref{haldclut} filter.
8600 The @code{nullsrc} source returns unprocessed video frames. It is
8601 mainly useful to be employed in analysis / debugging tools, or as the
8602 source for filters which ignore the input data.
8604 The @code{rgbtestsrc} source generates an RGB test pattern useful for
8605 detecting RGB vs BGR issues. You should see a red, green and blue
8606 stripe from top to bottom.
8608 The @code{smptebars} source generates a color bars pattern, based on
8609 the SMPTE Engineering Guideline EG 1-1990.
8611 The @code{smptehdbars} source generates a color bars pattern, based on
8612 the SMPTE RP 219-2002.
8614 The @code{testsrc} source generates a test video pattern, showing a
8615 color pattern, a scrolling gradient and a timestamp. This is mainly
8616 intended for testing purposes.
8618 The sources accept the following options:
8623 Specify the color of the source, only available in the @code{color}
8624 source. It can be the name of a color (case insensitive match) or a
8625 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
8626 default value is "black".
8629 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
8630 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
8631 pixels to be used as identity matrix for 3D lookup tables. Each component is
8632 coded on a @code{1/(N*N)} scale.
8635 Specify the size of the sourced video, it may be a string of the form
8636 @var{width}x@var{height}, or the name of a size abbreviation. The
8637 default value is "320x240".
8639 This option is not available with the @code{haldclutsrc} filter.
8642 Specify the frame rate of the sourced video, as the number of frames
8643 generated per second. It has to be a string in the format
8644 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
8645 number or a valid video frame rate abbreviation. The default value is
8649 Set the sample aspect ratio of the sourced video.
8652 Set the video duration of the sourced video. The accepted syntax is:
8654 [-]HH[:MM[:SS[.m...]]]
8657 See also the function @code{av_parse_time()}.
8659 If not specified, or the expressed duration is negative, the video is
8660 supposed to be generated forever.
8663 Set the number of decimals to show in the timestamp, only available in the
8664 @code{testsrc} source.
8666 The displayed timestamp value will correspond to the original
8667 timestamp value multiplied by the power of 10 of the specified
8668 value. Default value is 0.
8671 For example the following:
8673 testsrc=duration=5.3:size=qcif:rate=10
8676 will generate a video with a duration of 5.3 seconds, with size
8677 176x144 and a frame rate of 10 frames per second.
8679 The following graph description will generate a red source
8680 with an opacity of 0.2, with size "qcif" and a frame rate of 10
8683 color=c=red@@0.2:s=qcif:r=10
8686 If the input content is to be ignored, @code{nullsrc} can be used. The
8687 following command generates noise in the luminance plane by employing
8688 the @code{geq} filter:
8690 nullsrc=s=256x256, geq=random(1)*255:128:128
8693 @subsection Commands
8695 The @code{color} source supports the following commands:
8699 Set the color of the created image. Accepts the same syntax of the
8700 corresponding @option{color} option.
8703 @c man end VIDEO SOURCES
8705 @chapter Video Sinks
8706 @c man begin VIDEO SINKS
8708 Below is a description of the currently available video sinks.
8712 Buffer video frames, and make them available to the end of the filter
8715 This sink is mainly intended for a programmatic use, in particular
8716 through the interface defined in @file{libavfilter/buffersink.h}
8717 or the options system.
8719 It accepts a pointer to an AVBufferSinkContext structure, which
8720 defines the incoming buffers' formats, to be passed as the opaque
8721 parameter to @code{avfilter_init_filter} for initialization.
8725 Null video sink, do absolutely nothing with the input video. It is
8726 mainly useful as a template and to be employed in analysis / debugging
8729 @c man end VIDEO SINKS
8731 @chapter Multimedia Filters
8732 @c man begin MULTIMEDIA FILTERS
8734 Below is a description of the currently available multimedia filters.
8736 @section avectorscope
8738 Convert input audio to a video output, representing the audio vector
8741 The filter is used to measure the difference between channels of stereo
8742 audio stream. A monoaural signal, consisting of identical left and right
8743 signal, results in straight vertical line. Any stereo separation is visible
8744 as a deviation from this line, creating a Lissajous figure.
8745 If the straight (or deviation from it) but horizontal line appears this
8746 indicates that the left and right channels are out of phase.
8748 The filter accepts the following options:
8752 Set the vectorscope mode.
8754 Available values are:
8757 Lissajous rotated by 45 degrees.
8760 Same as above but not rotated.
8763 Default value is @samp{lissajous}.
8766 Set the video size for the output. Default value is @code{400x400}.
8769 Set the output frame rate. Default value is @code{25}.
8774 Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}.
8775 Allowed range is @code{[0, 255]}.
8780 Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}.
8781 Allowed range is @code{[0, 255]}.
8784 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
8787 @subsection Examples
8791 Complete example using @command{ffplay}:
8793 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
8794 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
8800 Concatenate audio and video streams, joining them together one after the
8803 The filter works on segments of synchronized video and audio streams. All
8804 segments must have the same number of streams of each type, and that will
8805 also be the number of streams at output.
8807 The filter accepts the following options:
8812 Set the number of segments. Default is 2.
8815 Set the number of output video streams, that is also the number of video
8816 streams in each segment. Default is 1.
8819 Set the number of output audio streams, that is also the number of video
8820 streams in each segment. Default is 0.
8823 Activate unsafe mode: do not fail if segments have a different format.
8827 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
8828 @var{a} audio outputs.
8830 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
8831 segment, in the same order as the outputs, then the inputs for the second
8834 Related streams do not always have exactly the same duration, for various
8835 reasons including codec frame size or sloppy authoring. For that reason,
8836 related synchronized streams (e.g. a video and its audio track) should be
8837 concatenated at once. The concat filter will use the duration of the longest
8838 stream in each segment (except the last one), and if necessary pad shorter
8839 audio streams with silence.
8841 For this filter to work correctly, all segments must start at timestamp 0.
8843 All corresponding streams must have the same parameters in all segments; the
8844 filtering system will automatically select a common pixel format for video
8845 streams, and a common sample format, sample rate and channel layout for
8846 audio streams, but other settings, such as resolution, must be converted
8847 explicitly by the user.
8849 Different frame rates are acceptable but will result in variable frame rate
8850 at output; be sure to configure the output file to handle it.
8852 @subsection Examples
8856 Concatenate an opening, an episode and an ending, all in bilingual version
8857 (video in stream 0, audio in streams 1 and 2):
8859 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
8860 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
8861 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
8862 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
8866 Concatenate two parts, handling audio and video separately, using the
8867 (a)movie sources, and adjusting the resolution:
8869 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
8870 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
8871 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
8873 Note that a desync will happen at the stitch if the audio and video streams
8874 do not have exactly the same duration in the first file.
8880 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
8881 it unchanged. By default, it logs a message at a frequency of 10Hz with the
8882 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
8883 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
8885 The filter also has a video output (see the @var{video} option) with a real
8886 time graph to observe the loudness evolution. The graphic contains the logged
8887 message mentioned above, so it is not printed anymore when this option is set,
8888 unless the verbose logging is set. The main graphing area contains the
8889 short-term loudness (3 seconds of analysis), and the gauge on the right is for
8890 the momentary loudness (400 milliseconds).
8892 More information about the Loudness Recommendation EBU R128 on
8893 @url{http://tech.ebu.ch/loudness}.
8895 The filter accepts the following options:
8900 Activate the video output. The audio stream is passed unchanged whether this
8901 option is set or no. The video stream will be the first output stream if
8902 activated. Default is @code{0}.
8905 Set the video size. This option is for video only. Default and minimum
8906 resolution is @code{640x480}.
8909 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
8910 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
8911 other integer value between this range is allowed.
8914 Set metadata injection. If set to @code{1}, the audio input will be segmented
8915 into 100ms output frames, each of them containing various loudness information
8916 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
8918 Default is @code{0}.
8921 Force the frame logging level.
8923 Available values are:
8926 information logging level
8928 verbose logging level
8931 By default, the logging level is set to @var{info}. If the @option{video} or
8932 the @option{metadata} options are set, it switches to @var{verbose}.
8935 @subsection Examples
8939 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
8941 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
8945 Run an analysis with @command{ffmpeg}:
8947 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
8951 @section interleave, ainterleave
8953 Temporally interleave frames from several inputs.
8955 @code{interleave} works with video inputs, @code{ainterleave} with audio.
8957 These filters read frames from several inputs and send the oldest
8958 queued frame to the output.
8960 Input streams must have a well defined, monotonically increasing frame
8963 In order to submit one frame to output, these filters need to enqueue
8964 at least one frame for each input, so they cannot work in case one
8965 input is not yet terminated and will not receive incoming frames.
8967 For example consider the case when one input is a @code{select} filter
8968 which always drop input frames. The @code{interleave} filter will keep
8969 reading from that input, but it will never be able to send new frames
8970 to output until the input will send an end-of-stream signal.
8972 Also, depending on inputs synchronization, the filters will drop
8973 frames in case one input receives more frames than the other ones, and
8974 the queue is already filled.
8976 These filters accept the following options:
8980 Set the number of different inputs, it is 2 by default.
8983 @subsection Examples
8987 Interleave frames belonging to different streams using @command{ffmpeg}:
8989 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
8993 Add flickering blur effect:
8995 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
8999 @section perms, aperms
9001 Set read/write permissions for the output frames.
9003 These filters are mainly aimed at developers to test direct path in the
9004 following filter in the filtergraph.
9006 The filters accept the following options:
9010 Select the permissions mode.
9012 It accepts the following values:
9015 Do nothing. This is the default.
9017 Set all the output frames read-only.
9019 Set all the output frames directly writable.
9021 Make the frame read-only if writable, and writable if read-only.
9023 Set each output frame read-only or writable randomly.
9027 Set the seed for the @var{random} mode, must be an integer included between
9028 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
9029 @code{-1}, the filter will try to use a good random seed on a best effort
9033 Note: in case of auto-inserted filter between the permission filter and the
9034 following one, the permission might not be received as expected in that
9035 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
9036 perms/aperms filter can avoid this problem.
9038 @section select, aselect
9040 Select frames to pass in output.
9042 This filter accepts the following options:
9047 Set expression, which is evaluated for each input frame.
9049 If the expression is evaluated to zero, the frame is discarded.
9051 If the evaluation result is negative or NaN, the frame is sent to the
9052 first output; otherwise it is sent to the output with index
9053 @code{ceil(val)-1}, assuming that the input index starts from 0.
9055 For example a value of @code{1.2} corresponds to the output with index
9056 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
9059 Set the number of outputs. The output to which to send the selected
9060 frame is based on the result of the evaluation. Default value is 1.
9063 The expression can contain the following constants:
9067 the sequential number of the filtered frame, starting from 0
9070 the sequential number of the selected frame, starting from 0
9072 @item prev_selected_n
9073 the sequential number of the last selected frame, NAN if undefined
9076 timebase of the input timestamps
9079 the PTS (Presentation TimeStamp) of the filtered video frame,
9080 expressed in @var{TB} units, NAN if undefined
9083 the PTS (Presentation TimeStamp) of the filtered video frame,
9084 expressed in seconds, NAN if undefined
9087 the PTS of the previously filtered video frame, NAN if undefined
9089 @item prev_selected_pts
9090 the PTS of the last previously filtered video frame, NAN if undefined
9092 @item prev_selected_t
9093 the PTS of the last previously selected video frame, NAN if undefined
9096 the PTS of the first video frame in the video, NAN if undefined
9099 the time of the first video frame in the video, NAN if undefined
9101 @item pict_type @emph{(video only)}
9102 the type of the filtered frame, can assume one of the following
9114 @item interlace_type @emph{(video only)}
9115 the frame interlace type, can assume one of the following values:
9118 the frame is progressive (not interlaced)
9120 the frame is top-field-first
9122 the frame is bottom-field-first
9125 @item consumed_sample_n @emph{(audio only)}
9126 the number of selected samples before the current frame
9128 @item samples_n @emph{(audio only)}
9129 the number of samples in the current frame
9131 @item sample_rate @emph{(audio only)}
9132 the input sample rate
9135 1 if the filtered frame is a key-frame, 0 otherwise
9138 the position in the file of the filtered frame, -1 if the information
9139 is not available (e.g. for synthetic video)
9141 @item scene @emph{(video only)}
9142 value between 0 and 1 to indicate a new scene; a low value reflects a low
9143 probability for the current frame to introduce a new scene, while a higher
9144 value means the current frame is more likely to be one (see the example below)
9148 The default value of the select expression is "1".
9150 @subsection Examples
9154 Select all frames in input:
9159 The example above is the same as:
9171 Select only I-frames:
9173 select='eq(pict_type\,I)'
9177 Select one frame every 100:
9179 select='not(mod(n\,100))'
9183 Select only frames contained in the 10-20 time interval:
9185 select=between(t\,10\,20)
9189 Select only I frames contained in the 10-20 time interval:
9191 select=between(t\,10\,20)*eq(pict_type\,I)
9195 Select frames with a minimum distance of 10 seconds:
9197 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
9201 Use aselect to select only audio frames with samples number > 100:
9203 aselect='gt(samples_n\,100)'
9207 Create a mosaic of the first scenes:
9209 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
9212 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
9216 Send even and odd frames to separate outputs, and compose them:
9218 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
9222 @section sendcmd, asendcmd
9224 Send commands to filters in the filtergraph.
9226 These filters read commands to be sent to other filters in the
9229 @code{sendcmd} must be inserted between two video filters,
9230 @code{asendcmd} must be inserted between two audio filters, but apart
9231 from that they act the same way.
9233 The specification of commands can be provided in the filter arguments
9234 with the @var{commands} option, or in a file specified by the
9235 @var{filename} option.
9237 These filters accept the following options:
9240 Set the commands to be read and sent to the other filters.
9242 Set the filename of the commands to be read and sent to the other
9246 @subsection Commands syntax
9248 A commands description consists of a sequence of interval
9249 specifications, comprising a list of commands to be executed when a
9250 particular event related to that interval occurs. The occurring event
9251 is typically the current frame time entering or leaving a given time
9254 An interval is specified by the following syntax:
9256 @var{START}[-@var{END}] @var{COMMANDS};
9259 The time interval is specified by the @var{START} and @var{END} times.
9260 @var{END} is optional and defaults to the maximum time.
9262 The current frame time is considered within the specified interval if
9263 it is included in the interval [@var{START}, @var{END}), that is when
9264 the time is greater or equal to @var{START} and is lesser than
9267 @var{COMMANDS} consists of a sequence of one or more command
9268 specifications, separated by ",", relating to that interval. The
9269 syntax of a command specification is given by:
9271 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
9274 @var{FLAGS} is optional and specifies the type of events relating to
9275 the time interval which enable sending the specified command, and must
9276 be a non-null sequence of identifier flags separated by "+" or "|" and
9277 enclosed between "[" and "]".
9279 The following flags are recognized:
9282 The command is sent when the current frame timestamp enters the
9283 specified interval. In other words, the command is sent when the
9284 previous frame timestamp was not in the given interval, and the
9288 The command is sent when the current frame timestamp leaves the
9289 specified interval. In other words, the command is sent when the
9290 previous frame timestamp was in the given interval, and the
9294 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
9297 @var{TARGET} specifies the target of the command, usually the name of
9298 the filter class or a specific filter instance name.
9300 @var{COMMAND} specifies the name of the command for the target filter.
9302 @var{ARG} is optional and specifies the optional list of argument for
9303 the given @var{COMMAND}.
9305 Between one interval specification and another, whitespaces, or
9306 sequences of characters starting with @code{#} until the end of line,
9307 are ignored and can be used to annotate comments.
9309 A simplified BNF description of the commands specification syntax
9312 @var{COMMAND_FLAG} ::= "enter" | "leave"
9313 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
9314 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
9315 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
9316 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
9317 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
9320 @subsection Examples
9324 Specify audio tempo change at second 4:
9326 asendcmd=c='4.0 atempo tempo 1.5',atempo
9330 Specify a list of drawtext and hue commands in a file.
9332 # show text in the interval 5-10
9333 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
9334 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
9336 # desaturate the image in the interval 15-20
9337 15.0-20.0 [enter] hue s 0,
9338 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
9340 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
9342 # apply an exponential saturation fade-out effect, starting from time 25
9343 25 [enter] hue s exp(25-t)
9346 A filtergraph allowing to read and process the above command list
9347 stored in a file @file{test.cmd}, can be specified with:
9349 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
9354 @section setpts, asetpts
9356 Change the PTS (presentation timestamp) of the input frames.
9358 @code{setpts} works on video frames, @code{asetpts} on audio frames.
9360 This filter accepts the following options:
9365 The expression which is evaluated for each frame to construct its timestamp.
9369 The expression is evaluated through the eval API and can contain the following
9374 frame rate, only defined for constant frame-rate video
9377 the presentation timestamp in input
9380 the count of the input frame for video or the number of consumed samples,
9381 not including the current frame for audio, starting from 0.
9383 @item NB_CONSUMED_SAMPLES
9384 the number of consumed samples, not including the current frame (only
9388 the number of samples in the current frame (only audio)
9390 @item SAMPLE_RATE, SR
9394 the PTS of the first frame
9397 the time in seconds of the first frame
9400 tell if the current frame is interlaced
9403 the time in seconds of the current frame
9406 original position in the file of the frame, or undefined if undefined
9407 for the current frame
9413 previous input time in seconds
9419 previous output time in seconds
9422 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
9426 wallclock (RTC) time at the start of the movie in microseconds
9429 timebase of the input timestamps
9433 @subsection Examples
9437 Start counting PTS from zero
9443 Apply fast motion effect:
9449 Apply slow motion effect:
9455 Set fixed rate of 25 frames per second:
9461 Set fixed rate 25 fps with some jitter:
9463 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
9467 Apply an offset of 10 seconds to the input PTS:
9473 Generate timestamps from a "live source" and rebase onto the current timebase:
9475 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
9479 Generate timestamps by counting samples:
9486 @section settb, asettb
9488 Set the timebase to use for the output frames timestamps.
9489 It is mainly useful for testing timebase configuration.
9491 This filter accepts the following options:
9496 The expression which is evaluated into the output timebase.
9500 The value for @option{tb} is an arithmetic expression representing a
9501 rational. The expression can contain the constants "AVTB" (the default
9502 timebase), "intb" (the input timebase) and "sr" (the sample rate,
9503 audio only). Default value is "intb".
9505 @subsection Examples
9509 Set the timebase to 1/25:
9515 Set the timebase to 1/10:
9521 Set the timebase to 1001/1000:
9527 Set the timebase to 2*intb:
9533 Set the default timebase value:
9539 @section showspectrum
9541 Convert input audio to a video output, representing the audio frequency
9544 The filter accepts the following options:
9548 Specify the video size for the output. Default value is @code{640x512}.
9551 Specify if the spectrum should slide along the window. Default value is
9555 Specify display mode.
9557 It accepts the following values:
9560 all channels are displayed in the same row
9562 all channels are displayed in separate rows
9565 Default value is @samp{combined}.
9568 Specify display color mode.
9570 It accepts the following values:
9573 each channel is displayed in a separate color
9575 each channel is is displayed using the same color scheme
9578 Default value is @samp{channel}.
9581 Specify scale used for calculating intensity color values.
9583 It accepts the following values:
9588 square root, default
9595 Default value is @samp{sqrt}.
9598 Set saturation modifier for displayed colors. Negative values provide
9599 alternative color scheme. @code{0} is no saturation at all.
9600 Saturation must be in [-10.0, 10.0] range.
9601 Default value is @code{1}.
9604 The usage is very similar to the showwaves filter; see the examples in that
9607 @subsection Examples
9611 Large window with logarithmic color scaling:
9613 showspectrum=s=1280x480:scale=log
9617 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
9619 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
9620 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
9626 Convert input audio to a video output, representing the samples waves.
9628 The filter accepts the following options:
9632 Specify the video size for the output. Default value is "600x240".
9637 Available values are:
9640 Draw a point for each sample.
9643 Draw a vertical line for each sample.
9646 Default value is @code{point}.
9649 Set the number of samples which are printed on the same column. A
9650 larger value will decrease the frame rate. Must be a positive
9651 integer. This option can be set only if the value for @var{rate}
9652 is not explicitly specified.
9655 Set the (approximate) output frame rate. This is done by setting the
9656 option @var{n}. Default value is "25".
9660 @subsection Examples
9664 Output the input file audio and the corresponding video representation
9667 amovie=a.mp3,asplit[out0],showwaves[out1]
9671 Create a synthetic signal and show it with showwaves, forcing a
9672 frame rate of 30 frames per second:
9674 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
9678 @section split, asplit
9680 Split input into several identical outputs.
9682 @code{asplit} works with audio input, @code{split} with video.
9684 The filter accepts a single parameter which specifies the number of outputs. If
9685 unspecified, it defaults to 2.
9687 @subsection Examples
9691 Create two separate outputs from the same input:
9693 [in] split [out0][out1]
9697 To create 3 or more outputs, you need to specify the number of
9700 [in] asplit=3 [out0][out1][out2]
9704 Create two separate outputs from the same input, one cropped and
9707 [in] split [splitout1][splitout2];
9708 [splitout1] crop=100:100:0:0 [cropout];
9709 [splitout2] pad=200:200:100:100 [padout];
9713 Create 5 copies of the input audio with @command{ffmpeg}:
9715 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
9721 Receive commands sent through a libzmq client, and forward them to
9722 filters in the filtergraph.
9724 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
9725 must be inserted between two video filters, @code{azmq} between two
9728 To enable these filters you need to install the libzmq library and
9729 headers and configure FFmpeg with @code{--enable-libzmq}.
9731 For more information about libzmq see:
9732 @url{http://www.zeromq.org/}
9734 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
9735 receives messages sent through a network interface defined by the
9736 @option{bind_address} option.
9738 The received message must be in the form:
9740 @var{TARGET} @var{COMMAND} [@var{ARG}]
9743 @var{TARGET} specifies the target of the command, usually the name of
9744 the filter class or a specific filter instance name.
9746 @var{COMMAND} specifies the name of the command for the target filter.
9748 @var{ARG} is optional and specifies the optional argument list for the
9749 given @var{COMMAND}.
9751 Upon reception, the message is processed and the corresponding command
9752 is injected into the filtergraph. Depending on the result, the filter
9753 will send a reply to the client, adopting the format:
9755 @var{ERROR_CODE} @var{ERROR_REASON}
9759 @var{MESSAGE} is optional.
9761 @subsection Examples
9763 Look at @file{tools/zmqsend} for an example of a zmq client which can
9764 be used to send commands processed by these filters.
9766 Consider the following filtergraph generated by @command{ffplay}
9768 ffplay -dumpgraph 1 -f lavfi "
9769 color=s=100x100:c=red [l];
9770 color=s=100x100:c=blue [r];
9771 nullsrc=s=200x100, zmq [bg];
9772 [bg][l] overlay [bg+l];
9773 [bg+l][r] overlay=x=100 "
9776 To change the color of the left side of the video, the following
9777 command can be used:
9779 echo Parsed_color_0 c yellow | tools/zmqsend
9782 To change the right side:
9784 echo Parsed_color_1 c pink | tools/zmqsend
9787 @c man end MULTIMEDIA FILTERS
9789 @chapter Multimedia Sources
9790 @c man begin MULTIMEDIA SOURCES
9792 Below is a description of the currently available multimedia sources.
9796 This is the same as @ref{movie} source, except it selects an audio
9802 Read audio and/or video stream(s) from a movie container.
9804 This filter accepts the following options:
9808 The name of the resource to read (not necessarily a file but also a device or a
9809 stream accessed through some protocol).
9811 @item format_name, f
9812 Specifies the format assumed for the movie to read, and can be either
9813 the name of a container or an input device. If not specified the
9814 format is guessed from @var{movie_name} or by probing.
9816 @item seek_point, sp
9817 Specifies the seek point in seconds, the frames will be output
9818 starting from this seek point, the parameter is evaluated with
9819 @code{av_strtod} so the numerical value may be suffixed by an IS
9820 postfix. Default value is "0".
9823 Specifies the streams to read. Several streams can be specified,
9824 separated by "+". The source will then have as many outputs, in the
9825 same order. The syntax is explained in the ``Stream specifiers''
9826 section in the ffmpeg manual. Two special names, "dv" and "da" specify
9827 respectively the default (best suited) video and audio stream. Default
9828 is "dv", or "da" if the filter is called as "amovie".
9830 @item stream_index, si
9831 Specifies the index of the video stream to read. If the value is -1,
9832 the best suited video stream will be automatically selected. Default
9833 value is "-1". Deprecated. If the filter is called "amovie", it will select
9834 audio instead of video.
9837 Specifies how many times to read the stream in sequence.
9838 If the value is less than 1, the stream will be read again and again.
9839 Default value is "1".
9841 Note that when the movie is looped the source timestamps are not
9842 changed, so it will generate non monotonically increasing timestamps.
9845 This filter allows to overlay a second video on top of main input of
9846 a filtergraph as shown in this graph:
9848 input -----------> deltapts0 --> overlay --> output
9851 movie --> scale--> deltapts1 -------+
9854 @subsection Examples
9858 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
9859 on top of the input labelled as "in":
9861 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
9862 [in] setpts=PTS-STARTPTS [main];
9863 [main][over] overlay=16:16 [out]
9867 Read from a video4linux2 device, and overlay it on top of the input
9870 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
9871 [in] setpts=PTS-STARTPTS [main];
9872 [main][over] overlay=16:16 [out]
9876 Read the first video stream and the audio stream with id 0x81 from
9877 dvd.vob; the video is connected to the pad named "video" and the audio is
9878 connected to the pad named "audio":
9880 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
9884 @c man end MULTIMEDIA SOURCES