1 @chapter Filtergraph description
2 @c man begin FILTERGRAPH DESCRIPTION
4 A filtergraph is a directed graph of connected filters. It can contain
5 cycles, and there can be multiple links between a pair of
6 filters. Each link has one input pad on one side connecting it to one
7 filter from which it takes its input, and one output pad on the other
8 side connecting it to the one filter accepting its output.
10 Each filter in a filtergraph is an instance of a filter class
11 registered in the application, which defines the features and the
12 number of input and output pads of the filter.
14 A filter with no input pads is called a "source", a filter with no
15 output pads is called a "sink".
17 @section Filtergraph syntax
19 A filtergraph can be represented using a textual representation, which
20 is recognized by the @code{-vf} option of the ff*
21 tools, and by the @code{avfilter_graph_parse()} function defined in
22 @file{libavfilter/avfiltergraph.h}.
24 A filterchain consists of a sequence of connected filters, each one
25 connected to the previous one in the sequence. A filterchain is
26 represented by a list of ","-separated filter descriptions.
28 A filtergraph consists of a sequence of filterchains. A sequence of
29 filterchains is represented by a list of ";"-separated filterchain
32 A filter is represented by a string of the form:
33 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
35 @var{filter_name} is the name of the filter class of which the
36 described filter is an instance of, and has to be the name of one of
37 the filter classes registered in the program.
38 The name of the filter class is optionally followed by a string
41 @var{arguments} is a string which contains the parameters used to
42 initialize the filter instance, and are described in the filter
45 The list of arguments can be quoted using the character "'" as initial
46 and ending mark, and the character '\' for escaping the characters
47 within the quoted text; otherwise the argument string is considered
48 terminated when the next special character (belonging to the set
49 "[]=;,") is encountered.
51 The name and arguments of the filter are optionally preceded and
52 followed by a list of link labels.
53 A link label allows to name a link and associate it to a filter output
54 or input pad. The preceding labels @var{in_link_1}
55 ... @var{in_link_N}, are associated to the filter input pads,
56 the following labels @var{out_link_1} ... @var{out_link_M}, are
57 associated to the output pads.
59 When two link labels with the same name are found in the
60 filtergraph, a link between the corresponding input and output pad is
63 If an output pad is not labelled, it is linked by default to the first
64 unlabelled input pad of the next filter in the filterchain.
65 For example in the filterchain:
67 nullsrc, split[L1], [L2]overlay, nullsink
69 the split filter instance has two output pads, and the overlay filter
70 instance two input pads. The first output pad of split is labelled
71 "L1", the first input pad of overlay is labelled "L2", and the second
72 output pad of split is linked to the second input pad of overlay,
73 which are both unlabelled.
75 In a complete filterchain all the unlabelled filter input and output
76 pads must be connected. A filtergraph is considered valid if all the
77 filter input and output pads of all the filterchains are connected.
79 Follows a BNF description for the filtergraph syntax:
81 @var{NAME} ::= sequence of alphanumeric characters and '_'
82 @var{LINKLABEL} ::= "[" @var{NAME} "]"
83 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
84 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
85 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
86 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
87 @var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
90 @c man end FILTERGRAPH DESCRIPTION
92 @chapter Audio Filters
93 @c man begin AUDIO FILTERS
95 When you configure your FFmpeg build, you can disable any of the
96 existing filters using @code{--disable-filters}.
97 The configure output will show the audio filters included in your
100 Below is a description of the currently available audio filters.
104 Convert the input audio format to the specified formats.
106 The filter accepts a string of the form:
107 "@var{sample_format}:@var{channel_layout}".
109 @var{sample_format} specifies the sample format, and can be a string or the
110 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
111 suffix for a planar sample format.
113 @var{channel_layout} specifies the channel layout, and can be a string
114 or the corresponding number value defined in @file{libavutil/audioconvert.h}.
116 The special parameter "auto", signifies that the filter will
117 automatically select the output format depending on the output filter.
119 Some examples follow.
123 Convert input to float, planar, stereo:
129 Convert input to unsigned 8-bit, automatically select out channel layout:
137 Convert the input audio to one of the specified formats. The framework will
138 negotiate the most appropriate format to minimize conversions.
140 The filter accepts three lists of formats, separated by ":", in the form:
141 "@var{sample_formats}:@var{channel_layouts}:@var{packing_formats}".
143 Elements in each list are separated by "," which has to be escaped in the
144 filtergraph specification.
146 The special parameter "all", in place of a list of elements, signifies all
149 Some examples follow:
151 aformat=u8\\,s16:mono:packed
153 aformat=s16:mono\\,stereo:all
158 Merge two audio streams into a single multi-channel stream.
160 This filter does not need any argument.
162 If the channel layouts of the inputs are disjoint, and therefore compatible,
163 the channel layout of the output will be set accordingly and the channels
164 will be reordered as necessary. If the channel layouts of the inputs are not
165 disjoint, the output will have all the channels of the first input then all
166 the channels of the second input, in that order, and the channel layout of
167 the output will be the default value corresponding to the total number of
170 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
171 is FC+BL+BR, then the output will be in 5.1, with the channels in the
172 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
173 first input, b1 is the first channel of the second input).
175 On the other hand, if both input are in stereo, the output channels will be
176 in the default order: a1, a2, b1, b2, and the channel layout will be
177 arbitrarily set to 4.0, which may or may not be the expected value.
179 Both inputs must have the same sample rate, format and packing.
181 If inputs do not have the same duration, the output will stop with the
184 Example: merge two mono files into a stereo stream:
186 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
189 If you need to do multiple merges (for instance multiple mono audio streams in
190 a single video media), you can do:
193 amovie=input.mkv:si=0 [a0];
194 amovie=input.mkv:si=1 [a1];
195 amovie=input.mkv:si=2 [a2];
196 amovie=input.mkv:si=3 [a3];
197 amovie=input.mkv:si=4 [a4];
198 amovie=input.mkv:si=5 [a5];
199 [a0][a1] amerge [x0];
200 [x0][a2] amerge [x1];
201 [x1][a3] amerge [x2];
202 [x2][a4] amerge [x3];
203 [x3][a5] amerge" -c:a pcm_s16le output.mkv
208 Pass the audio source unchanged to the output.
212 Resample the input audio to the specified sample rate.
214 The filter accepts exactly one parameter, the output sample rate. If not
215 specified then the filter will automatically convert between its input
216 and output sample rates.
218 For example, to resample the input audio to 44100Hz:
225 Show a line containing various information for each input audio frame.
226 The input audio is not modified.
228 The shown line contains a sequence of key/value pairs of the form
229 @var{key}:@var{value}.
231 A description of each shown parameter follows:
235 sequential number of the input frame, starting from 0
238 presentation TimeStamp of the input frame, expressed as a number of
239 time base units. The time base unit depends on the filter input pad, and
240 is usually 1/@var{sample_rate}.
243 presentation TimeStamp of the input frame, expressed as a number of
247 position of the frame in the input stream, -1 if this information in
248 unavailable and/or meaningless (for example in case of synthetic audio)
254 channel layout description
257 number of samples (per each channel) contained in the filtered frame
260 sample rate for the audio frame
263 if the packing format is planar, 0 if packed
266 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
269 Adler-32 checksum (printed in hexadecimal) for each input frame plane,
270 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
276 Pass on the input audio to two outputs. Both outputs are identical to
281 [in] asplit[out0], showaudio[out1]
284 will create two separate outputs from the same input, one cropped and
289 Forward two audio streams and control the order the buffers are forwarded.
291 The argument to the filter is an expression deciding which stream should be
292 forwarded next: if the result is negative, the first stream is forwarded; if
293 the result is positive or zero, the second stream is forwarded. It can use
294 the following variables:
298 number of buffers forwarded so far on each stream
300 number of samples forwarded so far on each stream
302 current timestamp of each stream
305 The default value is @code{t1-t2}, which means to always forward the stream
306 that has a smaller timestamp.
308 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
309 input, while avoiding too much of a desynchronization:
311 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
312 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
318 Make audio easier to listen to on headphones.
320 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
321 so that when listened to on headphones the stereo image is moved from
322 inside your head (standard for headphones) to outside and in front of
323 the listener (standard for speakers).
329 Mix channels with specific gain levels. The filter accepts the output
330 channel layout followed by a set of channels definitions.
332 This filter is also designed to remap efficiently the channels of an audio
335 The filter accepts parameters of the form:
336 "@var{l}:@var{outdef}:@var{outdef}:..."
340 output channel layout or number of channels
343 output channel specification, of the form:
344 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
347 output channel to define, either a channel name (FL, FR, etc.) or a channel
348 number (c0, c1, etc.)
351 multiplicative coefficient for the channel, 1 leaving the volume unchanged
354 input channel to use, see out_name for details; it is not possible to mix
355 named and numbered input channels
358 If the `=' in a channel specification is replaced by `<', then the gains for
359 that specification will be renormalized so that the total is 1, thus
360 avoiding clipping noise.
362 @subsection Mixing examples
364 For example, if you want to down-mix from stereo to mono, but with a bigger
365 factor for the left channel:
367 pan=1:c0=0.9*c0+0.1*c1
370 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
373 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
376 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
377 that should be preferred (see "-ac" option) unless you have very specific
380 @subsection Remapping examples
382 The channel remapping will be effective if, and only if:
385 @item gain coefficients are zeroes or ones,
386 @item only one input per channel output,
389 If all these conditions are satisfied, the filter will notify the user ("Pure
390 channel mapping detected"), and use an optimized and lossless method to do the
393 For example, if you have a 5.1 source and want a stereo audio stream by
394 dropping the extra channels:
396 pan="stereo: c0=FL : c1=FR"
399 Given the same source, you can also switch front left and front right channels
400 and keep the input channel layout:
402 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
405 If the input is a stereo audio stream, you can mute the front left channel (and
406 still keep the stereo channel layout) with:
411 Still with a stereo audio stream input, you can copy the right channel in both
412 front left and right:
414 pan="stereo: c0=FR : c1=FR"
417 @section silencedetect
419 Detect silence in an audio stream.
421 This filter logs a message when it detects that the input audio volume is less
422 or equal to a noise tolerance value for a duration greater or equal to the
423 minimum detected noise duration.
425 The printed times and duration are expressed in seconds.
429 Set silence duration until notification (default is 2 seconds).
432 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
433 specified value) or amplitude ratio. Default is -60dB, or 0.001.
436 Detect 5 seconds of silence with -50dB noise tolerance:
438 silencedetect=n=-50dB:d=5
441 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
442 tolerance in @file{silence.mp3}:
444 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
449 Adjust the input audio volume.
451 The filter accepts exactly one parameter @var{vol}, which expresses
452 how the audio volume will be increased or decreased.
454 Output values are clipped to the maximum value.
456 If @var{vol} is expressed as a decimal number, the output audio
457 volume is given by the relation:
459 @var{output_volume} = @var{vol} * @var{input_volume}
462 If @var{vol} is expressed as a decimal number followed by the string
463 "dB", the value represents the requested change in decibels of the
464 input audio power, and the output audio volume is given by the
467 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
470 Otherwise @var{vol} is considered an expression and its evaluated
471 value is used for computing the output audio volume according to the
474 Default value for @var{vol} is 1.0.
480 Half the input audio volume:
485 The above example is equivalent to:
491 Decrease input audio power by 12 decibels:
497 @c man end AUDIO FILTERS
499 @chapter Audio Sources
500 @c man begin AUDIO SOURCES
502 Below is a description of the currently available audio sources.
506 Buffer audio frames, and make them available to the filter chain.
508 This source is mainly intended for a programmatic use, in particular
509 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
511 It accepts the following mandatory parameters:
512 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
517 The sample rate of the incoming audio buffers.
520 The sample format of the incoming audio buffers.
521 Either a sample format name or its corresponging integer representation from
522 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
525 The channel layout of the incoming audio buffers.
526 Either a channel layout name from channel_layout_map in
527 @file{libavutil/audioconvert.c} or its corresponding integer representation
528 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
531 Either "packed" or "planar", or their integer representation: 0 or 1
538 abuffer=44100:s16:stereo:planar
541 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
542 Since the sample format with name "s16" corresponds to the number
543 1 and the "stereo" channel layout corresponds to the value 0x3, this is
546 abuffer=44100:1:0x3:1
551 Generate an audio signal specified by an expression.
553 This source accepts in input one or more expressions (one for each
554 channel), which are evaluated and used to generate a corresponding
557 It accepts the syntax: @var{exprs}[::@var{options}].
558 @var{exprs} is a list of expressions separated by ":", one for each
559 separate channel. The output channel layout depends on the number of
560 provided expressions, up to 8 channels are supported.
562 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
565 The description of the accepted options follows.
570 Set the minimum duration of the sourced audio. See the function
571 @code{av_parse_time()} for the accepted format.
572 Note that the resulting duration may be greater than the specified
573 duration, as the generated audio is always cut at the end of a
576 If not specified, or the expressed duration is negative, the audio is
577 supposed to be generated forever.
580 Set the number of samples per channel per each output frame,
584 Specify the sample rate, default to 44100.
587 Each expression in @var{exprs} can contain the following constants:
591 number of the evaluated sample, starting from 0
594 time of the evaluated sample expressed in seconds, starting from 0
613 Generate a sin signal with frequency of 440 Hz, set sample rate to
616 aevalsrc="sin(440*2*PI*t)::s=8000"
620 Generate white noise:
622 aevalsrc="-2+random(0)"
626 Generate an amplitude modulated signal:
628 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
632 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
634 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
641 Read an audio stream from a movie container.
643 It accepts the syntax: @var{movie_name}[:@var{options}] where
644 @var{movie_name} is the name of the resource to read (not necessarily
645 a file but also a device or a stream accessed through some protocol),
646 and @var{options} is an optional sequence of @var{key}=@var{value}
647 pairs, separated by ":".
649 The description of the accepted options follows.
654 Specify the format assumed for the movie to read, and can be either
655 the name of a container or an input device. If not specified the
656 format is guessed from @var{movie_name} or by probing.
659 Specify the seek point in seconds, the frames will be output
660 starting from this seek point, the parameter is evaluated with
661 @code{av_strtod} so the numerical value may be suffixed by an IS
662 postfix. Default value is "0".
664 @item stream_index, si
665 Specify the index of the audio stream to read. If the value is -1,
666 the best suited audio stream will be automatically selected. Default
673 Null audio source, return unprocessed audio frames. It is mainly useful
674 as a template and to be employed in analysis / debugging tools, or as
675 the source for filters which ignore the input data (for example the sox
678 It accepts an optional sequence of @var{key}=@var{value} pairs,
681 The description of the accepted options follows.
686 Specify the sample rate, and defaults to 44100.
688 @item channel_layout, cl
690 Specify the channel layout, and can be either an integer or a string
691 representing a channel layout. The default value of @var{channel_layout}
694 Check the channel_layout_map definition in
695 @file{libavcodec/audioconvert.c} for the mapping between strings and
696 channel layout values.
699 Set the number of samples per requested frames.
703 Follow some examples:
705 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
706 anullsrc=r=48000:cl=4
709 anullsrc=r=48000:cl=mono
712 @c man end AUDIO SOURCES
715 @c man begin AUDIO SINKS
717 Below is a description of the currently available audio sinks.
721 Buffer audio frames, and make them available to the end of filter chain.
723 This sink is mainly intended for programmatic use, in particular
724 through the interface defined in @file{libavfilter/buffersink.h}.
726 It requires a pointer to an AVABufferSinkContext structure, which
727 defines the incoming buffers' formats, to be passed as the opaque
728 parameter to @code{avfilter_init_filter} for initialization.
732 Null audio sink, do absolutely nothing with the input audio. It is
733 mainly useful as a template and to be employed in analysis / debugging
736 @c man end AUDIO SINKS
738 @chapter Video Filters
739 @c man begin VIDEO FILTERS
741 When you configure your FFmpeg build, you can disable any of the
742 existing filters using @code{--disable-filters}.
743 The configure output will show the video filters included in your
746 Below is a description of the currently available video filters.
750 Draw ASS (Advanced Substation Alpha) subtitles on top of input video
751 using the libass library.
753 To enable compilation of this filter you need to configure FFmpeg with
754 @code{--enable-libass}.
756 This filter accepts the syntax: @var{ass_filename}[:@var{options}],
757 where @var{ass_filename} is the filename of the ASS file to read, and
758 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
761 A description of the accepted options follows.
765 Specifies the size of the original video, the video for which the ASS file
766 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
767 necessary to correctly scale the fonts if the aspect ratio has been changed.
770 For example, to render the file @file{sub.ass} on top of the input
771 video, use the command:
778 Compute the bounding box for the non-black pixels in the input frame
781 This filter computes the bounding box containing all the pixels with a
782 luminance value greater than the minimum allowed value.
783 The parameters describing the bounding box are printed on the filter
788 Detect video intervals that are (almost) completely black. Can be
789 useful to detect chapter transitions, commercials, or invalid
790 recordings. Output lines contains the time for the start, end and
791 duration of the detected black interval expressed in seconds.
793 In order to display the output lines, you need to set the loglevel at
794 least to the AV_LOG_INFO value.
796 This filter accepts a list of options in the form of
797 @var{key}=@var{value} pairs separated by ":". A description of the
798 accepted options follows.
801 @item black_min_duration, d
802 Set the minimum detected black duration expressed in seconds. It must
803 be a non-negative floating point number.
805 Default value is 2.0.
807 @item picture_black_ratio_th, pic_th
808 Set the threshold for considering a picture "black".
809 Express the minimum value for the ratio:
811 @var{nb_black_pixels} / @var{nb_pixels}
814 for which a picture is considered black.
815 Default value is 0.98.
817 @item pixel_black_th, pix_th
818 Set the threshold for considering a pixel "black".
820 The threshold expresses the maximum pixel luminance value for which a
821 pixel is considered "black". The provided value is scaled according to
822 the following equation:
824 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
827 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
828 the input video format, the range is [0-255] for YUV full-range
829 formats and [16-235] for YUV non full-range formats.
831 Default value is 0.10.
834 The following example sets the maximum pixel threshold to the minimum
835 value, and detects only black intervals of 2 or more seconds:
837 blackdetect=d=2:pix_th=0.00
842 Detect frames that are (almost) completely black. Can be useful to
843 detect chapter transitions or commercials. Output lines consist of
844 the frame number of the detected frame, the percentage of blackness,
845 the position in the file if known or -1 and the timestamp in seconds.
847 In order to display the output lines, you need to set the loglevel at
848 least to the AV_LOG_INFO value.
850 The filter accepts the syntax:
852 blackframe[=@var{amount}:[@var{threshold}]]
855 @var{amount} is the percentage of the pixels that have to be below the
856 threshold, and defaults to 98.
858 @var{threshold} is the threshold below which a pixel value is
859 considered black, and defaults to 32.
863 Apply boxblur algorithm to the input video.
865 This filter accepts the parameters:
866 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
868 Chroma and alpha parameters are optional, if not specified they default
869 to the corresponding values set for @var{luma_radius} and
872 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
873 the radius in pixels of the box used for blurring the corresponding
874 input plane. They are expressions, and can contain the following
878 the input width and height in pixels
881 the input chroma image width and height in pixels
884 horizontal and vertical chroma subsample values. For example for the
885 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
888 The radius must be a non-negative number, and must not be greater than
889 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
890 and of @code{min(cw,ch)/2} for the chroma planes.
892 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
893 how many times the boxblur filter is applied to the corresponding
896 Some examples follow:
901 Apply a boxblur filter with luma, chroma, and alpha radius
908 Set luma radius to 2, alpha and chroma radius to 0
914 Set luma and chroma radius to a fraction of the video dimension
916 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
923 The colormatrix filter allows conversion between any of the following color
924 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
927 The syntax of the parameters is @var{source}:@var{destination}:
930 colormatrix=bt601:smpte240m
935 Copy the input source unchanged to the output. Mainly useful for
940 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
942 The @var{keep_aspect} parameter is optional, if specified and set to a
943 non-zero value will force the output display aspect ratio to be the
944 same of the input, by changing the output sample aspect ratio.
946 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
947 expressions containing the following constants:
951 the computed values for @var{x} and @var{y}. They are evaluated for
955 the input width and height
958 same as @var{in_w} and @var{in_h}
961 the output (cropped) width and height
964 same as @var{out_w} and @var{out_h}
967 same as @var{iw} / @var{ih}
970 input sample aspect ratio
973 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
976 horizontal and vertical chroma subsample values. For example for the
977 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
980 the number of input frame, starting from 0
983 the position in the file of the input frame, NAN if unknown
986 timestamp expressed in seconds, NAN if the input timestamp is unknown
990 The @var{out_w} and @var{out_h} parameters specify the expressions for
991 the width and height of the output (cropped) video. They are
992 evaluated just at the configuration of the filter.
994 The default value of @var{out_w} is "in_w", and the default value of
995 @var{out_h} is "in_h".
997 The expression for @var{out_w} may depend on the value of @var{out_h},
998 and the expression for @var{out_h} may depend on @var{out_w}, but they
999 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1000 evaluated after @var{out_w} and @var{out_h}.
1002 The @var{x} and @var{y} parameters specify the expressions for the
1003 position of the top-left corner of the output (non-cropped) area. They
1004 are evaluated for each frame. If the evaluated value is not valid, it
1005 is approximated to the nearest valid value.
1007 The default value of @var{x} is "(in_w-out_w)/2", and the default
1008 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
1009 the center of the input image.
1011 The expression for @var{x} may depend on @var{y}, and the expression
1012 for @var{y} may depend on @var{x}.
1014 Follow some examples:
1016 # crop the central input area with size 100x100
1019 # crop the central input area with size 2/3 of the input video
1020 "crop=2/3*in_w:2/3*in_h"
1022 # crop the input video central square
1025 # delimit the rectangle with the top-left corner placed at position
1026 # 100:100 and the right-bottom corner corresponding to the right-bottom
1027 # corner of the input image.
1028 crop=in_w-100:in_h-100:100:100
1030 # crop 10 pixels from the left and right borders, and 20 pixels from
1031 # the top and bottom borders
1032 "crop=in_w-2*10:in_h-2*20"
1034 # keep only the bottom right quarter of the input image
1035 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1037 # crop height for getting Greek harmony
1038 "crop=in_w:1/PHI*in_w"
1041 "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)"
1043 # erratic camera effect depending on timestamp
1044 "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)"
1046 # set x depending on the value of y
1047 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1052 Auto-detect crop size.
1054 Calculate necessary cropping parameters and prints the recommended
1055 parameters through the logging system. The detected dimensions
1056 correspond to the non-black area of the input video.
1058 It accepts the syntax:
1060 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1066 Threshold, which can be optionally specified from nothing (0) to
1067 everything (255), defaults to 24.
1070 Value which the width/height should be divisible by, defaults to
1071 16. The offset is automatically adjusted to center the video. Use 2 to
1072 get only even dimensions (needed for 4:2:2 video). 16 is best when
1073 encoding to most video codecs.
1076 Counter that determines after how many frames cropdetect will reset
1077 the previously detected largest video area and start over to detect
1078 the current optimal crop area. Defaults to 0.
1080 This can be useful when channel logos distort the video area. 0
1081 indicates never reset and return the largest area encountered during
1087 Suppress a TV station logo by a simple interpolation of the surrounding
1088 pixels. Just set a rectangle covering the logo and watch it disappear
1089 (and sometimes something even uglier appear - your mileage may vary).
1091 The filter accepts parameters as a string of the form
1092 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1093 @var{key}=@var{value} pairs, separated by ":".
1095 The description of the accepted parameters follows.
1100 Specify the top left corner coordinates of the logo. They must be
1104 Specify the width and height of the logo to clear. They must be
1108 Specify the thickness of the fuzzy edge of the rectangle (added to
1109 @var{w} and @var{h}). The default value is 4.
1112 When set to 1, a green rectangle is drawn on the screen to simplify
1113 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1114 @var{band} is set to 4. The default value is 0.
1118 Some examples follow.
1123 Set a rectangle covering the area with top left corner coordinates 0,0
1124 and size 100x77, setting a band of size 10:
1126 delogo=0:0:100:77:10
1130 As the previous example, but use named options:
1132 delogo=x=0:y=0:w=100:h=77:band=10
1139 Attempt to fix small changes in horizontal and/or vertical shift. This
1140 filter helps remove camera shake from hand-holding a camera, bumping a
1141 tripod, moving on a vehicle, etc.
1143 The filter accepts parameters as a string of the form
1144 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1146 A description of the accepted parameters follows.
1151 Specify a rectangular area where to limit the search for motion
1153 If desired the search for motion vectors can be limited to a
1154 rectangular area of the frame defined by its top left corner, width
1155 and height. These parameters have the same meaning as the drawbox
1156 filter which can be used to visualise the position of the bounding
1159 This is useful when simultaneous movement of subjects within the frame
1160 might be confused for camera motion by the motion vector search.
1162 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1163 then the full frame is used. This allows later options to be set
1164 without specifying the bounding box for the motion vector search.
1166 Default - search the whole frame.
1169 Specify the maximum extent of movement in x and y directions in the
1170 range 0-64 pixels. Default 16.
1173 Specify how to generate pixels to fill blanks at the edge of the
1174 frame. An integer from 0 to 3 as follows:
1177 Fill zeroes at blank locations
1179 Original image at blank locations
1181 Extruded edge value at blank locations
1183 Mirrored edge at blank locations
1186 The default setting is mirror edge at blank locations.
1189 Specify the blocksize to use for motion search. Range 4-128 pixels,
1193 Specify the contrast threshold for blocks. Only blocks with more than
1194 the specified contrast (difference between darkest and lightest
1195 pixels) will be considered. Range 1-255, default 125.
1198 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1199 search. Default - exhaustive search.
1202 If set then a detailed log of the motion search is written to the
1209 Draw a colored box on the input image.
1211 It accepts the syntax:
1213 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
1219 Specify the top left corner coordinates of the box. Default to 0.
1222 Specify the width and height of the box, if 0 they are interpreted as
1223 the input width and height. Default to 0.
1226 Specify the color of the box to write, it can be the name of a color
1227 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1230 Follow some examples:
1232 # draw a black box around the edge of the input image
1235 # draw a box with color red and an opacity of 50%
1236 drawbox=10:20:200:60:red@@0.5"
1241 Draw text string or text from specified file on top of video using the
1242 libfreetype library.
1244 To enable compilation of this filter you need to configure FFmpeg with
1245 @code{--enable-libfreetype}.
1247 The filter also recognizes strftime() sequences in the provided text
1248 and expands them accordingly. Check the documentation of strftime().
1250 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1253 The description of the accepted parameters follows.
1258 The font file to be used for drawing text. Path must be included.
1259 This parameter is mandatory.
1262 The text string to be drawn. The text must be a sequence of UTF-8
1264 This parameter is mandatory if no file is specified with the parameter
1268 A text file containing text to be drawn. The text must be a sequence
1269 of UTF-8 encoded characters.
1271 This parameter is mandatory if no text string is specified with the
1272 parameter @var{text}.
1274 If both text and textfile are specified, an error is thrown.
1277 The expressions which specify the offsets where text will be drawn
1278 within the video frame. They are relative to the top/left border of the
1281 The default value of @var{x} and @var{y} is "0".
1283 See below for the list of accepted constants.
1286 The font size to be used for drawing text.
1287 The default value of @var{fontsize} is 16.
1290 The color to be used for drawing fonts.
1291 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1292 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1293 The default value of @var{fontcolor} is "black".
1296 The color to be used for drawing box around text.
1297 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1298 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1299 The default value of @var{boxcolor} is "white".
1302 Used to draw a box around text using background color.
1303 Value should be either 1 (enable) or 0 (disable).
1304 The default value of @var{box} is 0.
1306 @item shadowx, shadowy
1307 The x and y offsets for the text shadow position with respect to the
1308 position of the text. They can be either positive or negative
1309 values. Default value for both is "0".
1312 The color to be used for drawing a shadow behind the drawn text. It
1313 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1314 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1315 The default value of @var{shadowcolor} is "black".
1318 Flags to be used for loading the fonts.
1320 The flags map the corresponding flags supported by libfreetype, and are
1321 a combination of the following values:
1328 @item vertical_layout
1329 @item force_autohint
1332 @item ignore_global_advance_width
1334 @item ignore_transform
1341 Default value is "render".
1343 For more information consult the documentation for the FT_LOAD_*
1347 The size in number of spaces to use for rendering the tab.
1351 If true, check and fix text coords to avoid clipping.
1354 The parameters for @var{x} and @var{y} are expressions containing the
1355 following constants:
1359 the input width and height
1362 the width of the rendered text
1365 the height of the rendered text
1368 the height of each text line
1371 input sample aspect ratio
1374 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1377 horizontal and vertical chroma subsample values. For example for the
1378 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1381 maximum glyph width, that is the maximum width for all the glyphs
1382 contained in the rendered text
1385 maximum glyph height, that is the maximum height for all the glyphs
1386 contained in the rendered text, it is equivalent to @var{ascent} -
1389 @item max_glyph_a, ascent
1391 the maximum distance from the baseline to the highest/upper grid
1392 coordinate used to place a glyph outline point, for all the rendered
1394 It is a positive value, due to the grid's orientation with the Y axis
1397 @item max_glyph_d, descent
1398 the maximum distance from the baseline to the lowest grid coordinate
1399 used to place a glyph outline point, for all the rendered glyphs.
1400 This is a negative value, due to the grid's orientation, with the Y axis
1404 the number of input frame, starting from 0
1407 timestamp expressed in seconds, NAN if the input timestamp is unknown
1410 initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
1411 with or without text parameter. @var{rate} option must be specified.
1414 frame rate (timecode only)
1417 If libavfilter was built with @code{--enable-fontconfig}, then
1418 @option{fontfile} can be a fontconfig pattern or omitted.
1420 Some examples follow.
1425 Draw "Test Text" with font FreeSerif, using the default values for the
1426 optional parameters.
1429 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1433 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1434 and y=50 (counting from the top-left corner of the screen), text is
1435 yellow with a red box around it. Both the text and the box have an
1439 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1440 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1443 Note that the double quotes are not necessary if spaces are not used
1444 within the parameter list.
1447 Show the text at the center of the video frame:
1449 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1453 Show a text line sliding from right to left in the last row of the video
1454 frame. The file @file{LONG_LINE} is assumed to contain a single line
1457 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1461 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1463 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1467 Draw a single green letter "g", at the center of the input video.
1468 The glyph baseline is placed at half screen height.
1470 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1474 Use fontconfig to set the font. Note that the colons need to be escaped.
1476 drawtext='fontfile=Linux Libertine O-40\\:style=Semibold:text=FFmpeg'
1481 For more information about libfreetype, check:
1482 @url{http://www.freetype.org/}.
1484 For more information about fontconfig, check:
1485 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
1489 Apply fade-in/out effect to input video.
1491 It accepts the parameters:
1492 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1494 @var{type} specifies if the effect type, can be either "in" for
1495 fade-in, or "out" for a fade-out effect.
1497 @var{start_frame} specifies the number of the start frame for starting
1498 to apply the fade effect.
1500 @var{nb_frames} specifies the number of frames for which the fade
1501 effect has to last. At the end of the fade-in effect the output video
1502 will have the same intensity as the input video, at the end of the
1503 fade-out transition the output video will be completely black.
1505 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1506 separated by ":". The description of the accepted options follows.
1513 @item start_frame, s
1514 See @var{start_frame}.
1517 See @var{nb_frames}.
1520 If set to 1, fade only alpha channel, if one exists on the input.
1524 A few usage examples follow, usable too as test scenarios.
1526 # fade in first 30 frames of video
1529 # fade out last 45 frames of a 200-frame video
1532 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1533 fade=in:0:25, fade=out:975:25
1535 # make first 5 frames black, then fade in from frame 5-24
1538 # fade in alpha over first 25 frames of video
1539 fade=in:0:25:alpha=1
1544 Transform the field order of the input video.
1546 It accepts one parameter which specifies the required field order that
1547 the input interlaced video will be transformed to. The parameter can
1548 assume one of the following values:
1552 output bottom field first
1554 output top field first
1557 Default value is "tff".
1559 Transformation is achieved by shifting the picture content up or down
1560 by one line, and filling the remaining line with appropriate picture content.
1561 This method is consistent with most broadcast field order converters.
1563 If the input video is not flagged as being interlaced, or it is already
1564 flagged as being of the required output field order then this filter does
1565 not alter the incoming video.
1567 This filter is very useful when converting to or from PAL DV material,
1568 which is bottom field first.
1572 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1577 Buffer input images and send them when they are requested.
1579 This filter is mainly useful when auto-inserted by the libavfilter
1582 The filter does not take parameters.
1586 Convert the input video to one of the specified pixel formats.
1587 Libavfilter will try to pick one that is supported for the input to
1590 The filter accepts a list of pixel format names, separated by ":",
1591 for example "yuv420p:monow:rgb24".
1593 Some examples follow:
1595 # convert the input video to the format "yuv420p"
1598 # convert the input video to any of the formats in the list
1599 format=yuv420p:yuv444p:yuv410p
1605 Apply a frei0r effect to the input video.
1607 To enable compilation of this filter you need to install the frei0r
1608 header and configure FFmpeg with @code{--enable-frei0r}.
1610 The filter supports the syntax:
1612 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1615 @var{filter_name} is the name to the frei0r effect to load. If the
1616 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1617 is searched in each one of the directories specified by the colon
1618 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1619 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1620 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1622 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1623 for the frei0r effect.
1625 A frei0r effect parameter can be a boolean (whose values are specified
1626 with "y" and "n"), a double, a color (specified by the syntax
1627 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1628 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1629 description), a position (specified by the syntax @var{X}/@var{Y},
1630 @var{X} and @var{Y} being float numbers) and a string.
1632 The number and kind of parameters depend on the loaded effect. If an
1633 effect parameter is not specified the default value is set.
1635 Some examples follow:
1637 # apply the distort0r effect, set the first two double parameters
1638 frei0r=distort0r:0.5:0.01
1640 # apply the colordistance effect, takes a color as first parameter
1641 frei0r=colordistance:0.2/0.3/0.4
1642 frei0r=colordistance:violet
1643 frei0r=colordistance:0x112233
1645 # apply the perspective effect, specify the top left and top right
1647 frei0r=perspective:0.2/0.2:0.8/0.2
1650 For more information see:
1651 @url{http://piksel.org/frei0r}
1655 Fix the banding artifacts that are sometimes introduced into nearly flat
1656 regions by truncation to 8bit color depth.
1657 Interpolate the gradients that should go where the bands are, and
1660 This filter is designed for playback only. Do not use it prior to
1661 lossy compression, because compression tends to lose the dither and
1662 bring back the bands.
1664 The filter takes two optional parameters, separated by ':':
1665 @var{strength}:@var{radius}
1667 @var{strength} is the maximum amount by which the filter will change
1668 any one pixel. Also the threshold for detecting nearly flat
1669 regions. Acceptable values range from .51 to 255, default value is
1670 1.2, out-of-range values will be clipped to the valid range.
1672 @var{radius} is the neighborhood to fit the gradient to. A larger
1673 radius makes for smoother gradients, but also prevents the filter from
1674 modifying the pixels near detailed regions. Acceptable values are
1675 8-32, default value is 16, out-of-range values will be clipped to the
1679 # default parameters
1688 Flip the input video horizontally.
1690 For example to horizontally flip the input video with @command{ffmpeg}:
1692 ffmpeg -i in.avi -vf "hflip" out.avi
1697 High precision/quality 3d denoise filter. This filter aims to reduce
1698 image noise producing smooth images and making still images really
1699 still. It should enhance compressibility.
1701 It accepts the following optional parameters:
1702 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1706 a non-negative float number which specifies spatial luma strength,
1709 @item chroma_spatial
1710 a non-negative float number which specifies spatial chroma strength,
1711 defaults to 3.0*@var{luma_spatial}/4.0
1714 a float number which specifies luma temporal strength, defaults to
1715 6.0*@var{luma_spatial}/4.0
1718 a float number which specifies chroma temporal strength, defaults to
1719 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1724 Interlaceing detect filter. This filter tries to detect if the input is
1725 interlaced or progressive. Top or bottom field first.
1727 @section lut, lutrgb, lutyuv
1729 Compute a look-up table for binding each pixel component input value
1730 to an output value, and apply it to input video.
1732 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1733 to an RGB input video.
1735 These filters accept in input a ":"-separated list of options, which
1736 specify the expressions used for computing the lookup table for the
1737 corresponding pixel component values.
1739 The @var{lut} filter requires either YUV or RGB pixel formats in
1740 input, and accepts the options:
1743 first pixel component
1745 second pixel component
1747 third pixel component
1749 fourth pixel component, corresponds to the alpha component
1752 The exact component associated to each option depends on the format in
1755 The @var{lutrgb} filter requires RGB pixel formats in input, and
1756 accepts the options:
1768 The @var{lutyuv} filter requires YUV pixel formats in input, and
1769 accepts the options:
1772 Y/luminance component
1781 The expressions can contain the following constants and functions:
1785 the input width and height
1788 input value for the pixel component
1791 the input value clipped in the @var{minval}-@var{maxval} range
1794 maximum value for the pixel component
1797 minimum value for the pixel component
1800 the negated value for the pixel component value clipped in the
1801 @var{minval}-@var{maxval} range , it corresponds to the expression
1802 "maxval-clipval+minval"
1805 the computed value in @var{val} clipped in the
1806 @var{minval}-@var{maxval} range
1808 @item gammaval(gamma)
1809 the computed gamma correction value of the pixel component value
1810 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1812 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1816 All expressions default to "val".
1818 Some examples follow:
1820 # negate input video
1821 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1822 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1824 # the above is the same as
1825 lutrgb="r=negval:g=negval:b=negval"
1826 lutyuv="y=negval:u=negval:v=negval"
1831 # remove chroma components, turns the video into a graytone image
1832 lutyuv="u=128:v=128"
1834 # apply a luma burning effect
1837 # remove green and blue components
1840 # set a constant alpha channel value on input
1841 format=rgba,lutrgb=a="maxval-minval/2"
1843 # correct luminance gamma by a 0.5 factor
1844 lutyuv=y=gammaval(0.5)
1849 Apply an MPlayer filter to the input video.
1851 This filter provides a wrapper around most of the filters of
1854 This wrapper is considered experimental. Some of the wrapped filters
1855 may not work properly and we may drop support for them, as they will
1856 be implemented natively into FFmpeg. Thus you should avoid
1857 depending on them when writing portable scripts.
1859 The filters accepts the parameters:
1860 @var{filter_name}[:=]@var{filter_params}
1862 @var{filter_name} is the name of a supported MPlayer filter,
1863 @var{filter_params} is a string containing the parameters accepted by
1866 The list of the currently supported filters follows:
1918 The parameter syntax and behavior for the listed filters are the same
1919 of the corresponding MPlayer filters. For detailed instructions check
1920 the "VIDEO FILTERS" section in the MPlayer manual.
1922 Some examples follow:
1924 # adjust gamma, brightness, contrast
1927 # tweak hue and saturation
1931 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1937 This filter accepts an integer in input, if non-zero it negates the
1938 alpha component (if available). The default value in input is 0.
1942 Force libavfilter not to use any of the specified pixel formats for the
1943 input to the next filter.
1945 The filter accepts a list of pixel format names, separated by ":",
1946 for example "yuv420p:monow:rgb24".
1948 Some examples follow:
1950 # force libavfilter to use a format different from "yuv420p" for the
1951 # input to the vflip filter
1952 noformat=yuv420p,vflip
1954 # convert the input video to any of the formats not contained in the list
1955 noformat=yuv420p:yuv444p:yuv410p
1960 Pass the video source unchanged to the output.
1964 Apply video transform using libopencv.
1966 To enable this filter install libopencv library and headers and
1967 configure FFmpeg with @code{--enable-libopencv}.
1969 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1971 @var{filter_name} is the name of the libopencv filter to apply.
1973 @var{filter_params} specifies the parameters to pass to the libopencv
1974 filter. If not specified the default values are assumed.
1976 Refer to the official libopencv documentation for more precise
1978 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1980 Follows the list of supported libopencv filters.
1985 Dilate an image by using a specific structuring element.
1986 This filter corresponds to the libopencv function @code{cvDilate}.
1988 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1990 @var{struct_el} represents a structuring element, and has the syntax:
1991 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1993 @var{cols} and @var{rows} represent the number of columns and rows of
1994 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1995 point, and @var{shape} the shape for the structuring element, and
1996 can be one of the values "rect", "cross", "ellipse", "custom".
1998 If the value for @var{shape} is "custom", it must be followed by a
1999 string of the form "=@var{filename}". The file with name
2000 @var{filename} is assumed to represent a binary image, with each
2001 printable character corresponding to a bright pixel. When a custom
2002 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
2003 or columns and rows of the read file are assumed instead.
2005 The default value for @var{struct_el} is "3x3+0x0/rect".
2007 @var{nb_iterations} specifies the number of times the transform is
2008 applied to the image, and defaults to 1.
2010 Follow some example:
2012 # use the default values
2015 # dilate using a structuring element with a 5x5 cross, iterate two times
2016 ocv=dilate=5x5+2x2/cross:2
2018 # read the shape from the file diamond.shape, iterate two times
2019 # the file diamond.shape may contain a pattern of characters like this:
2025 # the specified cols and rows are ignored (but not the anchor point coordinates)
2026 ocv=0x0+2x2/custom=diamond.shape:2
2031 Erode an image by using a specific structuring element.
2032 This filter corresponds to the libopencv function @code{cvErode}.
2034 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
2035 with the same syntax and semantics as the @ref{dilate} filter.
2039 Smooth the input video.
2041 The filter takes the following parameters:
2042 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
2044 @var{type} is the type of smooth filter to apply, and can be one of
2045 the following values: "blur", "blur_no_scale", "median", "gaussian",
2046 "bilateral". The default value is "gaussian".
2048 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
2049 parameters whose meanings depend on smooth type. @var{param1} and
2050 @var{param2} accept integer positive values or 0, @var{param3} and
2051 @var{param4} accept float values.
2053 The default value for @var{param1} is 3, the default value for the
2054 other parameters is 0.
2056 These parameters correspond to the parameters assigned to the
2057 libopencv function @code{cvSmooth}.
2062 Overlay one video on top of another.
2064 It takes two inputs and one output, the first input is the "main"
2065 video on which the second input is overlayed.
2067 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
2069 @var{x} is the x coordinate of the overlayed video on the main video,
2070 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
2071 the following parameters:
2074 @item main_w, main_h
2075 main input width and height
2078 same as @var{main_w} and @var{main_h}
2080 @item overlay_w, overlay_h
2081 overlay input width and height
2084 same as @var{overlay_w} and @var{overlay_h}
2087 @var{options} is an optional list of @var{key}=@var{value} pairs,
2090 The description of the accepted options follows.
2094 If set to 1, force the filter to accept inputs in the RGB
2095 color space. Default value is 0.
2098 Be aware that frames are taken from each input video in timestamp
2099 order, hence, if their initial timestamps differ, it is a a good idea
2100 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
2101 have them begin in the same zero timestamp, as it does the example for
2102 the @var{movie} filter.
2104 Follow some examples:
2106 # draw the overlay at 10 pixels from the bottom right
2107 # corner of the main video.
2108 overlay=main_w-overlay_w-10:main_h-overlay_h-10
2110 # insert a transparent PNG logo in the bottom left corner of the input
2111 movie=logo.png [logo];
2112 [in][logo] overlay=10:main_h-overlay_h-10 [out]
2114 # insert 2 different transparent PNG logos (second logo on bottom
2116 movie=logo1.png [logo1];
2117 movie=logo2.png [logo2];
2118 [in][logo1] overlay=10:H-h-10 [in+logo1];
2119 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
2121 # add a transparent color layer on top of the main video,
2122 # WxH specifies the size of the main input to the overlay filter
2123 color=red@.3:WxH [over]; [in][over] overlay [out]
2126 You can chain together more overlays but the efficiency of such
2127 approach is yet to be tested.
2131 Add paddings to the input image, and places the original input at the
2132 given coordinates @var{x}, @var{y}.
2134 It accepts the following parameters:
2135 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
2137 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
2138 expressions containing the following constants:
2142 the input video width and height
2145 same as @var{in_w} and @var{in_h}
2148 the output width and height, that is the size of the padded area as
2149 specified by the @var{width} and @var{height} expressions
2152 same as @var{out_w} and @var{out_h}
2155 x and y offsets as specified by the @var{x} and @var{y}
2156 expressions, or NAN if not yet specified
2159 same as @var{iw} / @var{ih}
2162 input sample aspect ratio
2165 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2168 horizontal and vertical chroma subsample values. For example for the
2169 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2172 Follows the description of the accepted parameters.
2177 Specify the size of the output image with the paddings added. If the
2178 value for @var{width} or @var{height} is 0, the corresponding input size
2179 is used for the output.
2181 The @var{width} expression can reference the value set by the
2182 @var{height} expression, and vice versa.
2184 The default value of @var{width} and @var{height} is 0.
2188 Specify the offsets where to place the input image in the padded area
2189 with respect to the top/left border of the output image.
2191 The @var{x} expression can reference the value set by the @var{y}
2192 expression, and vice versa.
2194 The default value of @var{x} and @var{y} is 0.
2198 Specify the color of the padded area, it can be the name of a color
2199 (case insensitive match) or a 0xRRGGBB[AA] sequence.
2201 The default value of @var{color} is "black".
2205 Some examples follow:
2208 # Add paddings with color "violet" to the input video. Output video
2209 # size is 640x480, the top-left corner of the input video is placed at
2211 pad=640:480:0:40:violet
2213 # pad the input to get an output with dimensions increased bt 3/2,
2214 # and put the input video at the center of the padded area
2215 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2217 # pad the input to get a squared output with size equal to the maximum
2218 # value between the input width and height, and put the input video at
2219 # the center of the padded area
2220 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2222 # pad the input to get a final w/h ratio of 16:9
2223 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2225 # for anamorphic video, in order to set the output display aspect ratio,
2226 # it is necessary to use sar in the expression, according to the relation:
2227 # (ih * X / ih) * sar = output_dar
2228 # X = output_dar / sar
2229 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
2231 # double output size and put the input video in the bottom-right
2232 # corner of the output padded area
2233 pad="2*iw:2*ih:ow-iw:oh-ih"
2236 @section pixdesctest
2238 Pixel format descriptor test filter, mainly useful for internal
2239 testing. The output video should be equal to the input video.
2243 format=monow, pixdesctest
2246 can be used to test the monowhite pixel format descriptor definition.
2250 Suppress a TV station logo, using an image file to determine which
2251 pixels comprise the logo. It works by filling in the pixels that
2252 comprise the logo with neighboring pixels.
2254 This filter requires one argument which specifies the filter bitmap
2255 file, which can be any image format supported by libavformat. The
2256 width and height of the image file must match those of the video
2257 stream being processed.
2259 Pixels in the provided bitmap image with a value of zero are not
2260 considered part of the logo, non-zero pixels are considered part of
2261 the logo. If you use white (255) for the logo and black (0) for the
2262 rest, you will be safe. For making the filter bitmap, it is
2263 recommended to take a screen capture of a black frame with the logo
2264 visible, and then using a threshold filter followed by the erode
2265 filter once or twice.
2267 If needed, little splotches can be fixed manually. Remember that if
2268 logo pixels are not covered, the filter quality will be much
2269 reduced. Marking too many pixels as part of the logo does not hurt as
2270 much, but it will increase the amount of blurring needed to cover over
2271 the image and will destroy more information than necessary, and extra
2272 pixels will slow things down on a large logo.
2276 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
2278 The scale filter forces the output display aspect ratio to be the same
2279 of the input, by changing the output sample aspect ratio.
2281 The parameters @var{width} and @var{height} are expressions containing
2282 the following constants:
2286 the input width and height
2289 same as @var{in_w} and @var{in_h}
2292 the output (cropped) width and height
2295 same as @var{out_w} and @var{out_h}
2298 same as @var{iw} / @var{ih}
2301 input sample aspect ratio
2304 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2307 horizontal and vertical chroma subsample values. For example for the
2308 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2311 If the input image format is different from the format requested by
2312 the next filter, the scale filter will convert the input to the
2315 If the value for @var{width} or @var{height} is 0, the respective input
2316 size is used for the output.
2318 If the value for @var{width} or @var{height} is -1, the scale filter will
2319 use, for the respective output size, a value that maintains the aspect
2320 ratio of the input image.
2322 The default value of @var{width} and @var{height} is 0.
2324 Valid values for the optional parameter @var{interl} are:
2328 force interlaced aware scaling
2331 select interlaced aware scaling depending on whether the source frames
2332 are flagged as interlaced or not
2335 Unless @var{interl} is set to one of the above options, interlaced scaling will not be used.
2337 Some examples follow:
2339 # scale the input video to a size of 200x100.
2342 # scale the input to 2x
2344 # the above is the same as
2347 # scale the input to 2x with forced interlaced scaling
2348 scale=2*iw:2*ih:interl=1
2350 # scale the input to half size
2353 # increase the width, and set the height to the same size
2356 # seek for Greek harmony
2360 # increase the height, and set the width to 3/2 of the height
2363 # increase the size, but make the size a multiple of the chroma
2364 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2366 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2367 scale='min(500\, iw*3/2):-1'
2371 Select frames to pass in output.
2373 It accepts in input an expression, which is evaluated for each input
2374 frame. If the expression is evaluated to a non-zero value, the frame
2375 is selected and passed to the output, otherwise it is discarded.
2377 The expression can contain the following constants:
2381 the sequential number of the filtered frame, starting from 0
2384 the sequential number of the selected frame, starting from 0
2386 @item prev_selected_n
2387 the sequential number of the last selected frame, NAN if undefined
2390 timebase of the input timestamps
2393 the PTS (Presentation TimeStamp) of the filtered video frame,
2394 expressed in @var{TB} units, NAN if undefined
2397 the PTS (Presentation TimeStamp) of the filtered video frame,
2398 expressed in seconds, NAN if undefined
2401 the PTS of the previously filtered video frame, NAN if undefined
2403 @item prev_selected_pts
2404 the PTS of the last previously filtered video frame, NAN if undefined
2406 @item prev_selected_t
2407 the PTS of the last previously selected video frame, NAN if undefined
2410 the PTS of the first video frame in the video, NAN if undefined
2413 the time of the first video frame in the video, NAN if undefined
2416 the type of the filtered frame, can assume one of the following
2428 @item interlace_type
2429 the frame interlace type, can assume one of the following values:
2432 the frame is progressive (not interlaced)
2434 the frame is top-field-first
2436 the frame is bottom-field-first
2440 1 if the filtered frame is a key-frame, 0 otherwise
2443 the position in the file of the filtered frame, -1 if the information
2444 is not available (e.g. for synthetic video)
2447 The default value of the select expression is "1".
2449 Some examples follow:
2452 # select all frames in input
2455 # the above is the same as:
2461 # select only I-frames
2462 select='eq(pict_type\,I)'
2464 # select one frame every 100
2465 select='not(mod(n\,100))'
2467 # select only frames contained in the 10-20 time interval
2468 select='gte(t\,10)*lte(t\,20)'
2470 # select only I frames contained in the 10-20 time interval
2471 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2473 # select frames with a minimum distance of 10 seconds
2474 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2477 @section setdar, setsar
2479 The @code{setdar} filter sets the Display Aspect Ratio for the filter
2482 This is done by changing the specified Sample (aka Pixel) Aspect
2483 Ratio, according to the following equation:
2485 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
2488 Keep in mind that the @code{setdar} filter does not modify the pixel
2489 dimensions of the video frame. Also the display aspect ratio set by
2490 this filter may be changed by later filters in the filterchain,
2491 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
2494 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
2495 the filter output video.
2497 Note that as a consequence of the application of this filter, the
2498 output display aspect ratio will change according to the equation
2501 Keep in mind that the sample aspect ratio set by the @code{setsar}
2502 filter may be changed by later filters in the filterchain, e.g. if
2503 another "setsar" or a "setdar" filter is applied.
2505 The @code{setdar} and @code{setsar} filters accept a parameter string
2506 which represents the wanted aspect ratio. The parameter can
2507 be a floating point number string, an expression, or a string of the form
2508 @var{num}:@var{den}, where @var{num} and @var{den} are the numerator
2509 and denominator of the aspect ratio. If the parameter is not
2510 specified, it is assumed the value "0:1".
2512 For example to change the display aspect ratio to 16:9, specify:
2517 The example above is equivalent to:
2522 To change the sample aspect ratio to 10:11, specify:
2529 Force field for the output video frame.
2531 The @code{setfield} filter marks the interlace type field for the
2532 output frames. It does not change the input frame, but only sets the
2533 corresponding property, which affects how the frame is treated by
2534 followig filters (e.g. @code{fieldorder} or @code{yadif}).
2536 It accepts a parameter representing an integer or a string, which can
2537 assume the following values:
2540 Keep the same field property.
2543 Mark the frame as bottom-field-first.
2546 Mark the frame as top-field-first.
2551 Change the PTS (presentation timestamp) of the input video frames.
2553 Accept in input an expression evaluated through the eval API, which
2554 can contain the following constants:
2558 the presentation timestamp in input
2561 the count of the input frame, starting from 0.
2564 the PTS of the first video frame
2567 tell if the current frame is interlaced
2570 original position in the file of the frame, or undefined if undefined
2571 for the current frame
2581 Some examples follow:
2584 # start counting PTS from zero
2596 # fixed rate 25 fps with some jitter
2597 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2602 Set the timebase to use for the output frames timestamps.
2603 It is mainly useful for testing timebase configuration.
2605 It accepts in input an arithmetic expression representing a rational.
2606 The expression can contain the constants "AVTB" (the
2607 default timebase), and "intb" (the input timebase).
2609 The default value for the input is "intb".
2611 Follow some examples.
2614 # set the timebase to 1/25
2617 # set the timebase to 1/10
2620 #set the timebase to 1001/1000
2623 #set the timebase to 2*intb
2626 #set the default timebase value
2632 Show a line containing various information for each input video frame.
2633 The input video is not modified.
2635 The shown line contains a sequence of key/value pairs of the form
2636 @var{key}:@var{value}.
2638 A description of each shown parameter follows:
2642 sequential number of the input frame, starting from 0
2645 Presentation TimeStamp of the input frame, expressed as a number of
2646 time base units. The time base unit depends on the filter input pad.
2649 Presentation TimeStamp of the input frame, expressed as a number of
2653 position of the frame in the input stream, -1 if this information in
2654 unavailable and/or meaningless (for example in case of synthetic video)
2660 sample aspect ratio of the input frame, expressed in the form
2664 size of the input frame, expressed in the form
2665 @var{width}x@var{height}
2668 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2669 for bottom field first)
2672 1 if the frame is a key frame, 0 otherwise
2675 picture type of the input frame ("I" for an I-frame, "P" for a
2676 P-frame, "B" for a B-frame, "?" for unknown type).
2677 Check also the documentation of the @code{AVPictureType} enum and of
2678 the @code{av_get_picture_type_char} function defined in
2679 @file{libavutil/avutil.h}.
2682 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2684 @item plane_checksum
2685 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2686 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2691 Pass the images of input video on to next video filter as multiple
2695 ffmpeg -i in.avi -vf "slicify=32" out.avi
2698 The filter accepts the slice height as parameter. If the parameter is
2699 not specified it will use the default value of 16.
2701 Adding this in the beginning of filter chains should make filtering
2702 faster due to better use of the memory cache.
2706 Pass on the input video to two outputs. Both outputs are identical to
2711 [in] split [splitout1][splitout2];
2712 [splitout1] crop=100:100:0:0 [cropout];
2713 [splitout2] pad=200:200:100:100 [padout];
2716 will create two separate outputs from the same input, one cropped and
2723 Select the most representative frame in a given sequence of consecutive frames.
2725 It accepts as argument the frames batch size to analyze (default @var{N}=100);
2726 in a set of @var{N} frames, the filter will pick one of them, and then handle
2727 the next batch of @var{N} frames until the end.
2729 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
2730 value will result in a higher memory usage, so a high value is not recommended.
2732 The following example extract one picture each 50 frames:
2737 Complete example of a thumbnail creation with @command{ffmpeg}:
2739 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
2744 Tile several successive frames together.
2746 It accepts as argument the tile size (i.e. the number of lines and columns)
2747 in the form "@var{w}x@var{h}".
2749 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
2752 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
2754 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
2755 duplicating each output frame to accomodate the originally detected frame
2760 Perform various types of temporal field interlacing.
2762 Frames are counted starting from 1, so the first input frame is
2765 This filter accepts a single parameter specifying the mode. Available
2770 Move odd frames into the upper field, even into the lower field,
2771 generating a double height frame at half framerate.
2774 Only output even frames, odd frames are dropped, generating a frame with
2775 unchanged height at half framerate.
2778 Only output odd frames, even frames are dropped, generating a frame with
2779 unchanged height at half framerate.
2782 Expand each frame to full height, but pad alternate lines with black,
2783 generating a frame with double height at the same input framerate.
2786 Interleave the upper field from odd frames with the lower field from
2787 even frames, generating a frame with unchanged height at half framerate.
2790 Interleave the lower field from odd frames with the upper field from
2791 even frames, generating a frame with unchanged height at half framerate.
2798 Transpose rows with columns in the input video and optionally flip it.
2800 It accepts a parameter representing an integer, which can assume the
2805 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2813 Rotate by 90 degrees clockwise, that is:
2821 Rotate by 90 degrees counterclockwise, that is:
2829 Rotate by 90 degrees clockwise and vertically flip, that is:
2839 Sharpen or blur the input video.
2841 It accepts the following parameters:
2842 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2844 Negative values for the amount will blur the input video, while positive
2845 values will sharpen. All parameters are optional and default to the
2846 equivalent of the string '5:5:1.0:5:5:0.0'.
2851 Set the luma matrix horizontal size. It can be an integer between 3
2852 and 13, default value is 5.
2855 Set the luma matrix vertical size. It can be an integer between 3
2856 and 13, default value is 5.
2859 Set the luma effect strength. It can be a float number between -2.0
2860 and 5.0, default value is 1.0.
2862 @item chroma_msize_x
2863 Set the chroma matrix horizontal size. It can be an integer between 3
2864 and 13, default value is 5.
2866 @item chroma_msize_y
2867 Set the chroma matrix vertical size. It can be an integer between 3
2868 and 13, default value is 5.
2871 Set the chroma effect strength. It can be a float number between -2.0
2872 and 5.0, default value is 0.0.
2877 # Strong luma sharpen effect parameters
2880 # Strong blur of both luma and chroma parameters
2881 unsharp=7:7:-2:7:7:-2
2883 # Use the default values with @command{ffmpeg}
2884 ffmpeg -i in.avi -vf "unsharp" out.mp4
2889 Flip the input video vertically.
2892 ffmpeg -i in.avi -vf "vflip" out.avi
2897 Deinterlace the input video ("yadif" means "yet another deinterlacing
2900 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2902 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2907 output 1 frame for each frame
2909 output 1 frame for each field
2911 like 0 but skips spatial interlacing check
2913 like 1 but skips spatial interlacing check
2918 @var{parity} specifies the picture field parity assumed for the input
2919 interlaced video, accepts one of the following values:
2923 assume top field first
2925 assume bottom field first
2927 enable automatic detection
2930 Default value is -1.
2931 If interlacing is unknown or decoder does not export this information,
2932 top field first will be assumed.
2934 @var{auto} specifies if deinterlacer should trust the interlaced flag
2935 and only deinterlace frames marked as interlaced
2939 deinterlace all frames
2941 only deinterlace frames marked as interlaced
2946 @c man end VIDEO FILTERS
2948 @chapter Video Sources
2949 @c man begin VIDEO SOURCES
2951 Below is a description of the currently available video sources.
2955 Buffer video frames, and make them available to the filter chain.
2957 This source is mainly intended for a programmatic use, in particular
2958 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2960 It accepts the following parameters:
2961 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}:@var{scale_params}
2963 All the parameters but @var{scale_params} need to be explicitly
2966 Follows the list of the accepted parameters.
2971 Specify the width and height of the buffered video frames.
2973 @item pix_fmt_string
2974 A string representing the pixel format of the buffered video frames.
2975 It may be a number corresponding to a pixel format, or a pixel format
2978 @item timebase_num, timebase_den
2979 Specify numerator and denomitor of the timebase assumed by the
2980 timestamps of the buffered frames.
2982 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2983 Specify numerator and denominator of the sample aspect ratio assumed
2984 by the video frames.
2987 Specify the optional parameters to be used for the scale filter which
2988 is automatically inserted when an input change is detected in the
2989 input size or format.
2994 buffer=320:240:yuv410p:1:24:1:1
2997 will instruct the source to accept video frames with size 320x240 and
2998 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2999 square pixels (1:1 sample aspect ratio).
3000 Since the pixel format with name "yuv410p" corresponds to the number 6
3001 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
3002 this example corresponds to:
3004 buffer=320:240:6:1:24:1:1
3009 Create a pattern generated by an elementary cellular automaton.
3011 The initial state of the cellular automaton can be defined through the
3012 @option{filename}, and @option{pattern} options. If such options are
3013 not specified an initial state is created randomly.
3015 At each new frame a new row in the video is filled with the result of
3016 the cellular automaton next generation. The behavior when the whole
3017 frame is filled is defined by the @option{scroll} option.
3019 This source accepts a list of options in the form of
3020 @var{key}=@var{value} pairs separated by ":". A description of the
3021 accepted options follows.
3025 Read the initial cellular automaton state, i.e. the starting row, from
3027 In the file, each non-whitespace character is considered an alive
3028 cell, a newline will terminate the row, and further characters in the
3029 file will be ignored.
3032 Read the initial cellular automaton state, i.e. the starting row, from
3033 the specified string.
3035 Each non-whitespace character in the string is considered an alive
3036 cell, a newline will terminate the row, and further characters in the
3037 string will be ignored.
3040 Set the video rate, that is the number of frames generated per second.
3043 @item random_fill_ratio, ratio
3044 Set the random fill ratio for the initial cellular automaton row. It
3045 is a floating point number value ranging from 0 to 1, defaults to
3048 This option is ignored when a file or a pattern is specified.
3050 @item random_seed, seed
3051 Set the seed for filling randomly the initial row, must be an integer
3052 included between 0 and UINT32_MAX. If not specified, or if explicitly
3053 set to -1, the filter will try to use a good random seed on a best
3057 Set the cellular automaton rule, it is a number ranging from 0 to 255.
3058 Default value is 110.
3061 Set the size of the output video.
3063 If @option{filename} or @option{pattern} is specified, the size is set
3064 by default to the width of the specified initial state row, and the
3065 height is set to @var{width} * PHI.
3067 If @option{size} is set, it must contain the width of the specified
3068 pattern string, and the specified pattern will be centered in the
3071 If a filename or a pattern string is not specified, the size value
3072 defaults to "320x518" (used for a randomly generated initial state).
3075 If set to 1, scroll the output upward when all the rows in the output
3076 have been already filled. If set to 0, the new generated row will be
3077 written over the top row just after the bottom row is filled.
3080 @item start_full, full
3081 If set to 1, completely fill the output with generated rows before
3082 outputting the first frame.
3083 This is the default behavior, for disabling set the value to 0.
3086 If set to 1, stitch the left and right row edges together.
3087 This is the default behavior, for disabling set the value to 0.
3090 @subsection Examples
3094 Read the initial state from @file{pattern}, and specify an output of
3097 cellauto=f=pattern:s=200x400
3101 Generate a random initial row with a width of 200 cells, with a fill
3104 cellauto=ratio=2/3:s=200x200
3108 Create a pattern generated by rule 18 starting by a single alive cell
3109 centered on an initial row with width 100:
3111 cellauto=p=@@:s=100x400:full=0:rule=18
3115 Specify a more elaborated initial pattern:
3117 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
3124 Provide an uniformly colored input.
3126 It accepts the following parameters:
3127 @var{color}:@var{frame_size}:@var{frame_rate}
3129 Follows the description of the accepted parameters.
3134 Specify the color of the source. It can be the name of a color (case
3135 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
3136 alpha specifier. The default value is "black".
3139 Specify the size of the sourced video, it may be a string of the form
3140 @var{width}x@var{height}, or the name of a size abbreviation. The
3141 default value is "320x240".
3144 Specify the frame rate of the sourced video, as the number of frames
3145 generated per second. It has to be a string in the format
3146 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3147 number or a valid video frame rate abbreviation. The default value is
3152 For example the following graph description will generate a red source
3153 with an opacity of 0.2, with size "qcif" and a frame rate of 10
3154 frames per second, which will be overlayed over the source connected
3155 to the pad with identifier "in".
3158 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
3163 Read a video stream from a movie container.
3165 It accepts the syntax: @var{movie_name}[:@var{options}] where
3166 @var{movie_name} is the name of the resource to read (not necessarily
3167 a file but also a device or a stream accessed through some protocol),
3168 and @var{options} is an optional sequence of @var{key}=@var{value}
3169 pairs, separated by ":".
3171 The description of the accepted options follows.
3175 @item format_name, f
3176 Specifies the format assumed for the movie to read, and can be either
3177 the name of a container or an input device. If not specified the
3178 format is guessed from @var{movie_name} or by probing.
3180 @item seek_point, sp
3181 Specifies the seek point in seconds, the frames will be output
3182 starting from this seek point, the parameter is evaluated with
3183 @code{av_strtod} so the numerical value may be suffixed by an IS
3184 postfix. Default value is "0".
3186 @item stream_index, si
3187 Specifies the index of the video stream to read. If the value is -1,
3188 the best suited video stream will be automatically selected. Default
3192 Specifies how many times to read the video stream in sequence.
3193 If the value is less than 1, the stream will be read again and again.
3194 Default value is "1".
3196 Note that when the movie is looped the source timestamps are not
3197 changed, so it will generate non monotonically increasing timestamps.
3200 This filter allows to overlay a second video on top of main input of
3201 a filtergraph as shown in this graph:
3203 input -----------> deltapts0 --> overlay --> output
3206 movie --> scale--> deltapts1 -------+
3209 Some examples follow:
3211 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
3212 # on top of the input labelled as "in".
3213 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3214 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3216 # read from a video4linux2 device, and overlay it on top of the input
3218 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3219 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3225 Generate various test patterns, as generated by the MPlayer test filter.
3227 The size of the generated video is fixed, and is 256x256.
3228 This source is useful in particular for testing encoding features.
3230 This source accepts an optional sequence of @var{key}=@var{value} pairs,
3231 separated by ":". The description of the accepted options follows.
3236 Specify the frame rate of the sourced video, as the number of frames
3237 generated per second. It has to be a string in the format
3238 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3239 number or a valid video frame rate abbreviation. The default value is
3243 Set the video duration of the sourced video. The accepted syntax is:
3245 [-]HH[:MM[:SS[.m...]]]
3248 See also the function @code{av_parse_time()}.
3250 If not specified, or the expressed duration is negative, the video is
3251 supposed to be generated forever.
3255 Set the number or the name of the test to perform. Supported tests are:
3270 Default value is "all", which will cycle through the list of all tests.
3273 For example the following:
3278 will generate a "dc_luma" test pattern.
3282 Provide a frei0r source.
3284 To enable compilation of this filter you need to install the frei0r
3285 header and configure FFmpeg with @code{--enable-frei0r}.
3287 The source supports the syntax:
3289 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
3292 @var{size} is the size of the video to generate, may be a string of the
3293 form @var{width}x@var{height} or a frame size abbreviation.
3294 @var{rate} is the rate of the video to generate, may be a string of
3295 the form @var{num}/@var{den} or a frame rate abbreviation.
3296 @var{src_name} is the name to the frei0r source to load. For more
3297 information regarding frei0r and how to set the parameters read the
3298 section @ref{frei0r} in the description of the video filters.
3300 Some examples follow:
3302 # generate a frei0r partik0l source with size 200x200 and frame rate 10
3303 # which is overlayed on the overlay filter main input
3304 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
3309 Generate a life pattern.
3311 This source is based on a generalization of John Conway's life game.
3313 The sourced input represents a life grid, each pixel represents a cell
3314 which can be in one of two possible states, alive or dead. Every cell
3315 interacts with its eight neighbours, which are the cells that are
3316 horizontally, vertically, or diagonally adjacent.
3318 At each interaction the grid evolves according to the adopted rule,
3319 which specifies the number of neighbor alive cells which will make a
3320 cell stay alive or born. The @option{rule} option allows to specify
3323 This source accepts a list of options in the form of
3324 @var{key}=@var{value} pairs separated by ":". A description of the
3325 accepted options follows.
3329 Set the file from which to read the initial grid state. In the file,
3330 each non-whitespace character is considered an alive cell, and newline
3331 is used to delimit the end of each row.
3333 If this option is not specified, the initial grid is generated
3337 Set the video rate, that is the number of frames generated per second.
3340 @item random_fill_ratio, ratio
3341 Set the random fill ratio for the initial random grid. It is a
3342 floating point number value ranging from 0 to 1, defaults to 1/PHI.
3343 It is ignored when a file is specified.
3345 @item random_seed, seed
3346 Set the seed for filling the initial random grid, must be an integer
3347 included between 0 and UINT32_MAX. If not specified, or if explicitly
3348 set to -1, the filter will try to use a good random seed on a best
3354 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
3355 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
3356 @var{NS} specifies the number of alive neighbor cells which make a
3357 live cell stay alive, and @var{NB} the number of alive neighbor cells
3358 which make a dead cell to become alive (i.e. to "born").
3359 "s" and "b" can be used in place of "S" and "B", respectively.
3361 Alternatively a rule can be specified by an 18-bits integer. The 9
3362 high order bits are used to encode the next cell state if it is alive
3363 for each number of neighbor alive cells, the low order bits specify
3364 the rule for "borning" new cells. Higher order bits encode for an
3365 higher number of neighbor cells.
3366 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
3367 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
3369 Default value is "S23/B3", which is the original Conway's game of life
3370 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
3371 cells, and will born a new cell if there are three alive cells around
3375 Set the size of the output video.
3377 If @option{filename} is specified, the size is set by default to the
3378 same size of the input file. If @option{size} is set, it must contain
3379 the size specified in the input file, and the initial grid defined in
3380 that file is centered in the larger resulting area.
3382 If a filename is not specified, the size value defaults to "320x240"
3383 (used for a randomly generated initial grid).
3386 If set to 1, stitch the left and right grid edges together, and the
3387 top and bottom edges also. Defaults to 1.
3390 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
3391 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
3392 value from 0 to 255.
3395 Set the color of living (or new born) cells.
3398 Set the color of dead cells. If @option{mold} is set, this is the first color
3399 used to represent a dead cell.
3402 Set mold color, for definitely dead and moldy cells.
3405 @subsection Examples
3409 Read a grid from @file{pattern}, and center it on a grid of size
3412 life=f=pattern:s=300x300
3416 Generate a random grid of size 200x200, with a fill ratio of 2/3:
3418 life=ratio=2/3:s=200x200
3422 Specify a custom rule for evolving a randomly generated grid:
3428 Full example with slow death effect (mold) using @command{ffplay}:
3430 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
3434 @section nullsrc, rgbtestsrc, testsrc
3436 The @code{nullsrc} source returns unprocessed video frames. It is
3437 mainly useful to be employed in analysis / debugging tools, or as the
3438 source for filters which ignore the input data.
3440 The @code{rgbtestsrc} source generates an RGB test pattern useful for
3441 detecting RGB vs BGR issues. You should see a red, green and blue
3442 stripe from top to bottom.
3444 The @code{testsrc} source generates a test video pattern, showing a
3445 color pattern, a scrolling gradient and a timestamp. This is mainly
3446 intended for testing purposes.
3448 These sources accept an optional sequence of @var{key}=@var{value} pairs,
3449 separated by ":". The description of the accepted options follows.
3454 Specify the size of the sourced video, it may be a string of the form
3455 @var{width}x@var{height}, or the name of a size abbreviation. The
3456 default value is "320x240".
3459 Specify the frame rate of the sourced video, as the number of frames
3460 generated per second. It has to be a string in the format
3461 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3462 number or a valid video frame rate abbreviation. The default value is
3466 Set the sample aspect ratio of the sourced video.
3469 Set the video duration of the sourced video. The accepted syntax is:
3471 [-]HH[:MM[:SS[.m...]]]
3474 See also the function @code{av_parse_time()}.
3476 If not specified, or the expressed duration is negative, the video is
3477 supposed to be generated forever.
3480 Set the number of decimals to show in the timestamp, only used in the
3481 @code{testsrc} source.
3483 The displayed timestamp value will correspond to the original
3484 timestamp value multiplied by the power of 10 of the specified
3485 value. Default value is 0.
3488 For example the following:
3490 testsrc=duration=5.3:size=qcif:rate=10
3493 will generate a video with a duration of 5.3 seconds, with size
3494 176x144 and a frame rate of 10 frames per second.
3496 If the input content is to be ignored, @code{nullsrc} can be used. The
3497 following command generates noise in the luminance plane by employing
3498 the @code{mp=geq} filter:
3500 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
3503 @c man end VIDEO SOURCES
3505 @chapter Video Sinks
3506 @c man begin VIDEO SINKS
3508 Below is a description of the currently available video sinks.
3512 Buffer video frames, and make them available to the end of the filter
3515 This sink is mainly intended for a programmatic use, in particular
3516 through the interface defined in @file{libavfilter/buffersink.h}.
3518 It does not require a string parameter in input, but you need to
3519 specify a pointer to a list of supported pixel formats terminated by
3520 -1 in the opaque parameter provided to @code{avfilter_init_filter}
3521 when initializing this sink.
3525 Null video sink, do absolutely nothing with the input video. It is
3526 mainly useful as a template and to be employed in analysis / debugging
3529 @c man end VIDEO SINKS