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 in input the name of the ass file to render.
758 For example, to render the file @file{sub.ass} on top of the input
759 video, use the command:
766 Detect frames that are (almost) completely black. Can be useful to
767 detect chapter transitions or commercials. Output lines consist of
768 the frame number of the detected frame, the percentage of blackness,
769 the position in the file if known or -1 and the timestamp in seconds.
771 In order to display the output lines, you need to set the loglevel at
772 least to the AV_LOG_INFO value.
774 The filter accepts the syntax:
776 blackframe[=@var{amount}:[@var{threshold}]]
779 @var{amount} is the percentage of the pixels that have to be below the
780 threshold, and defaults to 98.
782 @var{threshold} is the threshold below which a pixel value is
783 considered black, and defaults to 32.
787 Apply boxblur algorithm to the input video.
789 This filter accepts the parameters:
790 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
792 Chroma and alpha parameters are optional, if not specified they default
793 to the corresponding values set for @var{luma_radius} and
796 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
797 the radius in pixels of the box used for blurring the corresponding
798 input plane. They are expressions, and can contain the following
802 the input width and height in pixels
805 the input chroma image width and height in pixels
808 horizontal and vertical chroma subsample values. For example for the
809 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
812 The radius must be a non-negative number, and must not be greater than
813 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
814 and of @code{min(cw,ch)/2} for the chroma planes.
816 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
817 how many times the boxblur filter is applied to the corresponding
820 Some examples follow:
825 Apply a boxblur filter with luma, chroma, and alpha radius
832 Set luma radius to 2, alpha and chroma radius to 0
838 Set luma and chroma radius to a fraction of the video dimension
840 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
847 Copy the input source unchanged to the output. Mainly useful for
852 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
854 The parameters are expressions containing the following constants:
858 the computed values for @var{x} and @var{y}. They are evaluated for
862 the input width and height
865 same as @var{in_w} and @var{in_h}
868 the output (cropped) width and height
871 same as @var{out_w} and @var{out_h}
874 same as @var{iw} / @var{ih}
877 input sample aspect ratio
880 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
883 horizontal and vertical chroma subsample values. For example for the
884 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
887 the number of input frame, starting from 0
890 the position in the file of the input frame, NAN if unknown
893 timestamp expressed in seconds, NAN if the input timestamp is unknown
897 The @var{out_w} and @var{out_h} parameters specify the expressions for
898 the width and height of the output (cropped) video. They are
899 evaluated just at the configuration of the filter.
901 The default value of @var{out_w} is "in_w", and the default value of
902 @var{out_h} is "in_h".
904 The expression for @var{out_w} may depend on the value of @var{out_h},
905 and the expression for @var{out_h} may depend on @var{out_w}, but they
906 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
907 evaluated after @var{out_w} and @var{out_h}.
909 The @var{x} and @var{y} parameters specify the expressions for the
910 position of the top-left corner of the output (non-cropped) area. They
911 are evaluated for each frame. If the evaluated value is not valid, it
912 is approximated to the nearest valid value.
914 The default value of @var{x} is "(in_w-out_w)/2", and the default
915 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
916 the center of the input image.
918 The expression for @var{x} may depend on @var{y}, and the expression
919 for @var{y} may depend on @var{x}.
921 Follow some examples:
923 # crop the central input area with size 100x100
926 # crop the central input area with size 2/3 of the input video
927 "crop=2/3*in_w:2/3*in_h"
929 # crop the input video central square
932 # delimit the rectangle with the top-left corner placed at position
933 # 100:100 and the right-bottom corner corresponding to the right-bottom
934 # corner of the input image.
935 crop=in_w-100:in_h-100:100:100
937 # crop 10 pixels from the left and right borders, and 20 pixels from
938 # the top and bottom borders
939 "crop=in_w-2*10:in_h-2*20"
941 # keep only the bottom right quarter of the input image
942 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
944 # crop height for getting Greek harmony
945 "crop=in_w:1/PHI*in_w"
948 "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)"
950 # erratic camera effect depending on timestamp
951 "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)"
953 # set x depending on the value of y
954 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
959 Auto-detect crop size.
961 Calculate necessary cropping parameters and prints the recommended
962 parameters through the logging system. The detected dimensions
963 correspond to the non-black area of the input video.
965 It accepts the syntax:
967 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
973 Threshold, which can be optionally specified from nothing (0) to
974 everything (255), defaults to 24.
977 Value which the width/height should be divisible by, defaults to
978 16. The offset is automatically adjusted to center the video. Use 2 to
979 get only even dimensions (needed for 4:2:2 video). 16 is best when
980 encoding to most video codecs.
983 Counter that determines after how many frames cropdetect will reset
984 the previously detected largest video area and start over to detect
985 the current optimal crop area. Defaults to 0.
987 This can be useful when channel logos distort the video area. 0
988 indicates never reset and return the largest area encountered during
994 Suppress a TV station logo by a simple interpolation of the surrounding
995 pixels. Just set a rectangle covering the logo and watch it disappear
996 (and sometimes something even uglier appear - your mileage may vary).
998 The filter accepts parameters as a string of the form
999 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1000 @var{key}=@var{value} pairs, separated by ":".
1002 The description of the accepted parameters follows.
1007 Specify the top left corner coordinates of the logo. They must be
1011 Specify the width and height of the logo to clear. They must be
1015 Specify the thickness of the fuzzy edge of the rectangle (added to
1016 @var{w} and @var{h}). The default value is 4.
1019 When set to 1, a green rectangle is drawn on the screen to simplify
1020 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1021 @var{band} is set to 4. The default value is 0.
1025 Some examples follow.
1030 Set a rectangle covering the area with top left corner coordinates 0,0
1031 and size 100x77, setting a band of size 10:
1033 delogo=0:0:100:77:10
1037 As the previous example, but use named options:
1039 delogo=x=0:y=0:w=100:h=77:band=10
1046 Attempt to fix small changes in horizontal and/or vertical shift. This
1047 filter helps remove camera shake from hand-holding a camera, bumping a
1048 tripod, moving on a vehicle, etc.
1050 The filter accepts parameters as a string of the form
1051 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1053 A description of the accepted parameters follows.
1058 Specify a rectangular area where to limit the search for motion
1060 If desired the search for motion vectors can be limited to a
1061 rectangular area of the frame defined by its top left corner, width
1062 and height. These parameters have the same meaning as the drawbox
1063 filter which can be used to visualise the position of the bounding
1066 This is useful when simultaneous movement of subjects within the frame
1067 might be confused for camera motion by the motion vector search.
1069 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1070 then the full frame is used. This allows later options to be set
1071 without specifying the bounding box for the motion vector search.
1073 Default - search the whole frame.
1076 Specify the maximum extent of movement in x and y directions in the
1077 range 0-64 pixels. Default 16.
1080 Specify how to generate pixels to fill blanks at the edge of the
1081 frame. An integer from 0 to 3 as follows:
1084 Fill zeroes at blank locations
1086 Original image at blank locations
1088 Extruded edge value at blank locations
1090 Mirrored edge at blank locations
1093 The default setting is mirror edge at blank locations.
1096 Specify the blocksize to use for motion search. Range 4-128 pixels,
1100 Specify the contrast threshold for blocks. Only blocks with more than
1101 the specified contrast (difference between darkest and lightest
1102 pixels) will be considered. Range 1-255, default 125.
1105 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1106 search. Default - exhaustive search.
1109 If set then a detailed log of the motion search is written to the
1116 Draw a colored box on the input image.
1118 It accepts the syntax:
1120 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
1126 Specify the top left corner coordinates of the box. Default to 0.
1129 Specify the width and height of the box, if 0 they are interpreted as
1130 the input width and height. Default to 0.
1133 Specify the color of the box to write, it can be the name of a color
1134 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1137 Follow some examples:
1139 # draw a black box around the edge of the input image
1142 # draw a box with color red and an opacity of 50%
1143 drawbox=10:20:200:60:red@@0.5"
1148 Draw text string or text from specified file on top of video using the
1149 libfreetype library.
1151 To enable compilation of this filter you need to configure FFmpeg with
1152 @code{--enable-libfreetype}.
1154 The filter also recognizes strftime() sequences in the provided text
1155 and expands them accordingly. Check the documentation of strftime().
1157 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1160 The description of the accepted parameters follows.
1165 The font file to be used for drawing text. Path must be included.
1166 This parameter is mandatory.
1169 The text string to be drawn. The text must be a sequence of UTF-8
1171 This parameter is mandatory if no file is specified with the parameter
1175 A text file containing text to be drawn. The text must be a sequence
1176 of UTF-8 encoded characters.
1178 This parameter is mandatory if no text string is specified with the
1179 parameter @var{text}.
1181 If both text and textfile are specified, an error is thrown.
1184 The expressions which specify the offsets where text will be drawn
1185 within the video frame. They are relative to the top/left border of the
1188 The default value of @var{x} and @var{y} is "0".
1190 See below for the list of accepted constants.
1193 The font size to be used for drawing text.
1194 The default value of @var{fontsize} is 16.
1197 The color to be used for drawing fonts.
1198 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1199 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1200 The default value of @var{fontcolor} is "black".
1203 The color to be used for drawing box around text.
1204 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1205 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1206 The default value of @var{boxcolor} is "white".
1209 Used to draw a box around text using background color.
1210 Value should be either 1 (enable) or 0 (disable).
1211 The default value of @var{box} is 0.
1213 @item shadowx, shadowy
1214 The x and y offsets for the text shadow position with respect to the
1215 position of the text. They can be either positive or negative
1216 values. Default value for both is "0".
1219 The color to be used for drawing a shadow behind the drawn text. It
1220 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1221 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1222 The default value of @var{shadowcolor} is "black".
1225 Flags to be used for loading the fonts.
1227 The flags map the corresponding flags supported by libfreetype, and are
1228 a combination of the following values:
1235 @item vertical_layout
1236 @item force_autohint
1239 @item ignore_global_advance_width
1241 @item ignore_transform
1248 Default value is "render".
1250 For more information consult the documentation for the FT_LOAD_*
1254 The size in number of spaces to use for rendering the tab.
1258 If true, check and fix text coords to avoid clipping.
1261 The parameters for @var{x} and @var{y} are expressions containing the
1262 following constants:
1266 the input width and height
1269 the width of the rendered text
1272 the height of the rendered text
1275 the height of each text line
1278 input sample aspect ratio
1281 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1284 horizontal and vertical chroma subsample values. For example for the
1285 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1288 maximum glyph width, that is the maximum width for all the glyphs
1289 contained in the rendered text
1292 maximum glyph height, that is the maximum height for all the glyphs
1293 contained in the rendered text, it is equivalent to @var{ascent} -
1296 @item max_glyph_a, ascent
1298 the maximum distance from the baseline to the highest/upper grid
1299 coordinate used to place a glyph outline point, for all the rendered
1301 It is a positive value, due to the grid's orientation with the Y axis
1304 @item max_glyph_d, descent
1305 the maximum distance from the baseline to the lowest grid coordinate
1306 used to place a glyph outline point, for all the rendered glyphs.
1307 This is a negative value, due to the grid's orientation, with the Y axis
1311 the number of input frame, starting from 0
1314 timestamp expressed in seconds, NAN if the input timestamp is unknown
1317 initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
1318 with or without text parameter. @var{rate} option must be specified.
1321 frame rate (timecode only)
1324 Some examples follow.
1329 Draw "Test Text" with font FreeSerif, using the default values for the
1330 optional parameters.
1333 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1337 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1338 and y=50 (counting from the top-left corner of the screen), text is
1339 yellow with a red box around it. Both the text and the box have an
1343 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1344 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1347 Note that the double quotes are not necessary if spaces are not used
1348 within the parameter list.
1351 Show the text at the center of the video frame:
1353 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1357 Show a text line sliding from right to left in the last row of the video
1358 frame. The file @file{LONG_LINE} is assumed to contain a single line
1361 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1365 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1367 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1371 Draw a single green letter "g", at the center of the input video.
1372 The glyph baseline is placed at half screen height.
1374 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1379 For more information about libfreetype, check:
1380 @url{http://www.freetype.org/}.
1384 Apply fade-in/out effect to input video.
1386 It accepts the parameters:
1387 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1389 @var{type} specifies if the effect type, can be either "in" for
1390 fade-in, or "out" for a fade-out effect.
1392 @var{start_frame} specifies the number of the start frame for starting
1393 to apply the fade effect.
1395 @var{nb_frames} specifies the number of frames for which the fade
1396 effect has to last. At the end of the fade-in effect the output video
1397 will have the same intensity as the input video, at the end of the
1398 fade-out transition the output video will be completely black.
1400 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1401 separated by ":". The description of the accepted options follows.
1408 @item start_frame, s
1409 See @var{start_frame}.
1412 See @var{nb_frames}.
1415 If set to 1, fade only alpha channel, if one exists on the input.
1419 A few usage examples follow, usable too as test scenarios.
1421 # fade in first 30 frames of video
1424 # fade out last 45 frames of a 200-frame video
1427 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1428 fade=in:0:25, fade=out:975:25
1430 # make first 5 frames black, then fade in from frame 5-24
1433 # fade in alpha over first 25 frames of video
1434 fade=in:0:25:alpha=1
1439 Transform the field order of the input video.
1441 It accepts one parameter which specifies the required field order that
1442 the input interlaced video will be transformed to. The parameter can
1443 assume one of the following values:
1447 output bottom field first
1449 output top field first
1452 Default value is "tff".
1454 Transformation is achieved by shifting the picture content up or down
1455 by one line, and filling the remaining line with appropriate picture content.
1456 This method is consistent with most broadcast field order converters.
1458 If the input video is not flagged as being interlaced, or it is already
1459 flagged as being of the required output field order then this filter does
1460 not alter the incoming video.
1462 This filter is very useful when converting to or from PAL DV material,
1463 which is bottom field first.
1467 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1472 Buffer input images and send them when they are requested.
1474 This filter is mainly useful when auto-inserted by the libavfilter
1477 The filter does not take parameters.
1481 Convert the input video to one of the specified pixel formats.
1482 Libavfilter will try to pick one that is supported for the input to
1485 The filter accepts a list of pixel format names, separated by ":",
1486 for example "yuv420p:monow:rgb24".
1488 Some examples follow:
1490 # convert the input video to the format "yuv420p"
1493 # convert the input video to any of the formats in the list
1494 format=yuv420p:yuv444p:yuv410p
1500 Apply a frei0r effect to the input video.
1502 To enable compilation of this filter you need to install the frei0r
1503 header and configure FFmpeg with @code{--enable-frei0r}.
1505 The filter supports the syntax:
1507 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1510 @var{filter_name} is the name to the frei0r effect to load. If the
1511 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1512 is searched in each one of the directories specified by the colon
1513 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1514 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1515 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1517 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1518 for the frei0r effect.
1520 A frei0r effect parameter can be a boolean (whose values are specified
1521 with "y" and "n"), a double, a color (specified by the syntax
1522 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1523 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1524 description), a position (specified by the syntax @var{X}/@var{Y},
1525 @var{X} and @var{Y} being float numbers) and a string.
1527 The number and kind of parameters depend on the loaded effect. If an
1528 effect parameter is not specified the default value is set.
1530 Some examples follow:
1532 # apply the distort0r effect, set the first two double parameters
1533 frei0r=distort0r:0.5:0.01
1535 # apply the colordistance effect, takes a color as first parameter
1536 frei0r=colordistance:0.2/0.3/0.4
1537 frei0r=colordistance:violet
1538 frei0r=colordistance:0x112233
1540 # apply the perspective effect, specify the top left and top right
1542 frei0r=perspective:0.2/0.2:0.8/0.2
1545 For more information see:
1546 @url{http://piksel.org/frei0r}
1550 Fix the banding artifacts that are sometimes introduced into nearly flat
1551 regions by truncation to 8bit color depth.
1552 Interpolate the gradients that should go where the bands are, and
1555 This filter is designed for playback only. Do not use it prior to
1556 lossy compression, because compression tends to lose the dither and
1557 bring back the bands.
1559 The filter takes two optional parameters, separated by ':':
1560 @var{strength}:@var{radius}
1562 @var{strength} is the maximum amount by which the filter will change
1563 any one pixel. Also the threshold for detecting nearly flat
1564 regions. Acceptable values range from .51 to 255, default value is
1565 1.2, out-of-range values will be clipped to the valid range.
1567 @var{radius} is the neighborhood to fit the gradient to. A larger
1568 radius makes for smoother gradients, but also prevents the filter from
1569 modifying the pixels near detailed regions. Acceptable values are
1570 8-32, default value is 16, out-of-range values will be clipped to the
1574 # default parameters
1583 Flip the input video horizontally.
1585 For example to horizontally flip the input video with @command{ffmpeg}:
1587 ffmpeg -i in.avi -vf "hflip" out.avi
1592 High precision/quality 3d denoise filter. This filter aims to reduce
1593 image noise producing smooth images and making still images really
1594 still. It should enhance compressibility.
1596 It accepts the following optional parameters:
1597 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1601 a non-negative float number which specifies spatial luma strength,
1604 @item chroma_spatial
1605 a non-negative float number which specifies spatial chroma strength,
1606 defaults to 3.0*@var{luma_spatial}/4.0
1609 a float number which specifies luma temporal strength, defaults to
1610 6.0*@var{luma_spatial}/4.0
1613 a float number which specifies chroma temporal strength, defaults to
1614 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1617 @section lut, lutrgb, lutyuv
1619 Compute a look-up table for binding each pixel component input value
1620 to an output value, and apply it to input video.
1622 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1623 to an RGB input video.
1625 These filters accept in input a ":"-separated list of options, which
1626 specify the expressions used for computing the lookup table for the
1627 corresponding pixel component values.
1629 The @var{lut} filter requires either YUV or RGB pixel formats in
1630 input, and accepts the options:
1633 first pixel component
1635 second pixel component
1637 third pixel component
1639 fourth pixel component, corresponds to the alpha component
1642 The exact component associated to each option depends on the format in
1645 The @var{lutrgb} filter requires RGB pixel formats in input, and
1646 accepts the options:
1658 The @var{lutyuv} filter requires YUV pixel formats in input, and
1659 accepts the options:
1662 Y/luminance component
1671 The expressions can contain the following constants and functions:
1675 the input width and height
1678 input value for the pixel component
1681 the input value clipped in the @var{minval}-@var{maxval} range
1684 maximum value for the pixel component
1687 minimum value for the pixel component
1690 the negated value for the pixel component value clipped in the
1691 @var{minval}-@var{maxval} range , it corresponds to the expression
1692 "maxval-clipval+minval"
1695 the computed value in @var{val} clipped in the
1696 @var{minval}-@var{maxval} range
1698 @item gammaval(gamma)
1699 the computed gamma correction value of the pixel component value
1700 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1702 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1706 All expressions default to "val".
1708 Some examples follow:
1710 # negate input video
1711 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1712 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1714 # the above is the same as
1715 lutrgb="r=negval:g=negval:b=negval"
1716 lutyuv="y=negval:u=negval:v=negval"
1721 # remove chroma components, turns the video into a graytone image
1722 lutyuv="u=128:v=128"
1724 # apply a luma burning effect
1727 # remove green and blue components
1730 # set a constant alpha channel value on input
1731 format=rgba,lutrgb=a="maxval-minval/2"
1733 # correct luminance gamma by a 0.5 factor
1734 lutyuv=y=gammaval(0.5)
1739 Apply an MPlayer filter to the input video.
1741 This filter provides a wrapper around most of the filters of
1744 This wrapper is considered experimental. Some of the wrapped filters
1745 may not work properly and we may drop support for them, as they will
1746 be implemented natively into FFmpeg. Thus you should avoid
1747 depending on them when writing portable scripts.
1749 The filters accepts the parameters:
1750 @var{filter_name}[:=]@var{filter_params}
1752 @var{filter_name} is the name of a supported MPlayer filter,
1753 @var{filter_params} is a string containing the parameters accepted by
1756 The list of the currently supported filters follows:
1810 The parameter syntax and behavior for the listed filters are the same
1811 of the corresponding MPlayer filters. For detailed instructions check
1812 the "VIDEO FILTERS" section in the MPlayer manual.
1814 Some examples follow:
1816 # remove a logo by interpolating the surrounding pixels
1817 mp=delogo=200:200:80:20:1
1819 # adjust gamma, brightness, contrast
1822 # tweak hue and saturation
1826 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1832 This filter accepts an integer in input, if non-zero it negates the
1833 alpha component (if available). The default value in input is 0.
1837 Force libavfilter not to use any of the specified pixel formats for the
1838 input to the next filter.
1840 The filter accepts a list of pixel format names, separated by ":",
1841 for example "yuv420p:monow:rgb24".
1843 Some examples follow:
1845 # force libavfilter to use a format different from "yuv420p" for the
1846 # input to the vflip filter
1847 noformat=yuv420p,vflip
1849 # convert the input video to any of the formats not contained in the list
1850 noformat=yuv420p:yuv444p:yuv410p
1855 Pass the video source unchanged to the output.
1859 Apply video transform using libopencv.
1861 To enable this filter install libopencv library and headers and
1862 configure FFmpeg with @code{--enable-libopencv}.
1864 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1866 @var{filter_name} is the name of the libopencv filter to apply.
1868 @var{filter_params} specifies the parameters to pass to the libopencv
1869 filter. If not specified the default values are assumed.
1871 Refer to the official libopencv documentation for more precise
1873 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1875 Follows the list of supported libopencv filters.
1880 Dilate an image by using a specific structuring element.
1881 This filter corresponds to the libopencv function @code{cvDilate}.
1883 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1885 @var{struct_el} represents a structuring element, and has the syntax:
1886 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1888 @var{cols} and @var{rows} represent the number of columns and rows of
1889 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1890 point, and @var{shape} the shape for the structuring element, and
1891 can be one of the values "rect", "cross", "ellipse", "custom".
1893 If the value for @var{shape} is "custom", it must be followed by a
1894 string of the form "=@var{filename}". The file with name
1895 @var{filename} is assumed to represent a binary image, with each
1896 printable character corresponding to a bright pixel. When a custom
1897 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1898 or columns and rows of the read file are assumed instead.
1900 The default value for @var{struct_el} is "3x3+0x0/rect".
1902 @var{nb_iterations} specifies the number of times the transform is
1903 applied to the image, and defaults to 1.
1905 Follow some example:
1907 # use the default values
1910 # dilate using a structuring element with a 5x5 cross, iterate two times
1911 ocv=dilate=5x5+2x2/cross:2
1913 # read the shape from the file diamond.shape, iterate two times
1914 # the file diamond.shape may contain a pattern of characters like this:
1920 # the specified cols and rows are ignored (but not the anchor point coordinates)
1921 ocv=0x0+2x2/custom=diamond.shape:2
1926 Erode an image by using a specific structuring element.
1927 This filter corresponds to the libopencv function @code{cvErode}.
1929 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1930 with the same syntax and semantics as the @ref{dilate} filter.
1934 Smooth the input video.
1936 The filter takes the following parameters:
1937 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1939 @var{type} is the type of smooth filter to apply, and can be one of
1940 the following values: "blur", "blur_no_scale", "median", "gaussian",
1941 "bilateral". The default value is "gaussian".
1943 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1944 parameters whose meanings depend on smooth type. @var{param1} and
1945 @var{param2} accept integer positive values or 0, @var{param3} and
1946 @var{param4} accept float values.
1948 The default value for @var{param1} is 3, the default value for the
1949 other parameters is 0.
1951 These parameters correspond to the parameters assigned to the
1952 libopencv function @code{cvSmooth}.
1957 Overlay one video on top of another.
1959 It takes two inputs and one output, the first input is the "main"
1960 video on which the second input is overlayed.
1962 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
1964 @var{x} is the x coordinate of the overlayed video on the main video,
1965 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
1966 the following parameters:
1969 @item main_w, main_h
1970 main input width and height
1973 same as @var{main_w} and @var{main_h}
1975 @item overlay_w, overlay_h
1976 overlay input width and height
1979 same as @var{overlay_w} and @var{overlay_h}
1982 @var{options} is an optional list of @var{key}=@var{value} pairs,
1985 The description of the accepted options follows.
1989 If set to 1, force the filter to accept inputs in the RGB
1990 color space. Default value is 0.
1993 Be aware that frames are taken from each input video in timestamp
1994 order, hence, if their initial timestamps differ, it is a a good idea
1995 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1996 have them begin in the same zero timestamp, as it does the example for
1997 the @var{movie} filter.
1999 Follow some examples:
2001 # draw the overlay at 10 pixels from the bottom right
2002 # corner of the main video.
2003 overlay=main_w-overlay_w-10:main_h-overlay_h-10
2005 # insert a transparent PNG logo in the bottom left corner of the input
2006 movie=logo.png [logo];
2007 [in][logo] overlay=10:main_h-overlay_h-10 [out]
2009 # insert 2 different transparent PNG logos (second logo on bottom
2011 movie=logo1.png [logo1];
2012 movie=logo2.png [logo2];
2013 [in][logo1] overlay=10:H-h-10 [in+logo1];
2014 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
2016 # add a transparent color layer on top of the main video,
2017 # WxH specifies the size of the main input to the overlay filter
2018 color=red@.3:WxH [over]; [in][over] overlay [out]
2021 You can chain together more overlays but the efficiency of such
2022 approach is yet to be tested.
2026 Add paddings to the input image, and places the original input at the
2027 given coordinates @var{x}, @var{y}.
2029 It accepts the following parameters:
2030 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
2032 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
2033 expressions containing the following constants:
2037 the input video width and height
2040 same as @var{in_w} and @var{in_h}
2043 the output width and height, that is the size of the padded area as
2044 specified by the @var{width} and @var{height} expressions
2047 same as @var{out_w} and @var{out_h}
2050 x and y offsets as specified by the @var{x} and @var{y}
2051 expressions, or NAN if not yet specified
2054 same as @var{iw} / @var{ih}
2057 input sample aspect ratio
2060 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2063 horizontal and vertical chroma subsample values. For example for the
2064 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2067 Follows the description of the accepted parameters.
2072 Specify the size of the output image with the paddings added. If the
2073 value for @var{width} or @var{height} is 0, the corresponding input size
2074 is used for the output.
2076 The @var{width} expression can reference the value set by the
2077 @var{height} expression, and vice versa.
2079 The default value of @var{width} and @var{height} is 0.
2083 Specify the offsets where to place the input image in the padded area
2084 with respect to the top/left border of the output image.
2086 The @var{x} expression can reference the value set by the @var{y}
2087 expression, and vice versa.
2089 The default value of @var{x} and @var{y} is 0.
2093 Specify the color of the padded area, it can be the name of a color
2094 (case insensitive match) or a 0xRRGGBB[AA] sequence.
2096 The default value of @var{color} is "black".
2100 Some examples follow:
2103 # Add paddings with color "violet" to the input video. Output video
2104 # size is 640x480, the top-left corner of the input video is placed at
2106 pad=640:480:0:40:violet
2108 # pad the input to get an output with dimensions increased bt 3/2,
2109 # and put the input video at the center of the padded area
2110 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2112 # pad the input to get a squared output with size equal to the maximum
2113 # value between the input width and height, and put the input video at
2114 # the center of the padded area
2115 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2117 # pad the input to get a final w/h ratio of 16:9
2118 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2120 # for anamorphic video, in order to set the output display aspect ratio,
2121 # it is necessary to use sar in the expression, according to the relation:
2122 # (ih * X / ih) * sar = output_dar
2123 # X = output_dar / sar
2124 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
2126 # double output size and put the input video in the bottom-right
2127 # corner of the output padded area
2128 pad="2*iw:2*ih:ow-iw:oh-ih"
2131 @section pixdesctest
2133 Pixel format descriptor test filter, mainly useful for internal
2134 testing. The output video should be equal to the input video.
2138 format=monow, pixdesctest
2141 can be used to test the monowhite pixel format descriptor definition.
2145 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
2147 The parameters @var{width} and @var{height} are expressions containing
2148 the following constants:
2152 the input width and height
2155 same as @var{in_w} and @var{in_h}
2158 the output (cropped) width and height
2161 same as @var{out_w} and @var{out_h}
2164 same as @var{iw} / @var{ih}
2167 input sample aspect ratio
2170 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2173 horizontal and vertical chroma subsample values. For example for the
2174 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2177 If the input image format is different from the format requested by
2178 the next filter, the scale filter will convert the input to the
2181 If the value for @var{width} or @var{height} is 0, the respective input
2182 size is used for the output.
2184 If the value for @var{width} or @var{height} is -1, the scale filter will
2185 use, for the respective output size, a value that maintains the aspect
2186 ratio of the input image.
2188 The default value of @var{width} and @var{height} is 0.
2190 Valid values for the optional parameter @var{interl} are:
2194 force interlaced aware scaling
2197 select interlaced aware scaling depending on whether the source frames
2198 are flagged as interlaced or not
2201 Some examples follow:
2203 # scale the input video to a size of 200x100.
2206 # scale the input to 2x
2208 # the above is the same as
2211 # scale the input to half size
2214 # increase the width, and set the height to the same size
2217 # seek for Greek harmony
2221 # increase the height, and set the width to 3/2 of the height
2224 # increase the size, but make the size a multiple of the chroma
2225 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2227 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2228 scale='min(500\, iw*3/2):-1'
2232 Select frames to pass in output.
2234 It accepts in input an expression, which is evaluated for each input
2235 frame. If the expression is evaluated to a non-zero value, the frame
2236 is selected and passed to the output, otherwise it is discarded.
2238 The expression can contain the following constants:
2242 the sequential number of the filtered frame, starting from 0
2245 the sequential number of the selected frame, starting from 0
2247 @item prev_selected_n
2248 the sequential number of the last selected frame, NAN if undefined
2251 timebase of the input timestamps
2254 the PTS (Presentation TimeStamp) of the filtered video frame,
2255 expressed in @var{TB} units, NAN if undefined
2258 the PTS (Presentation TimeStamp) of the filtered video frame,
2259 expressed in seconds, NAN if undefined
2262 the PTS of the previously filtered video frame, NAN if undefined
2264 @item prev_selected_pts
2265 the PTS of the last previously filtered video frame, NAN if undefined
2267 @item prev_selected_t
2268 the PTS of the last previously selected video frame, NAN if undefined
2271 the PTS of the first video frame in the video, NAN if undefined
2274 the time of the first video frame in the video, NAN if undefined
2277 the type of the filtered frame, can assume one of the following
2289 @item interlace_type
2290 the frame interlace type, can assume one of the following values:
2293 the frame is progressive (not interlaced)
2295 the frame is top-field-first
2297 the frame is bottom-field-first
2301 1 if the filtered frame is a key-frame, 0 otherwise
2304 the position in the file of the filtered frame, -1 if the information
2305 is not available (e.g. for synthetic video)
2308 The default value of the select expression is "1".
2310 Some examples follow:
2313 # select all frames in input
2316 # the above is the same as:
2322 # select only I-frames
2323 select='eq(pict_type\,I)'
2325 # select one frame every 100
2326 select='not(mod(n\,100))'
2328 # select only frames contained in the 10-20 time interval
2329 select='gte(t\,10)*lte(t\,20)'
2331 # select only I frames contained in the 10-20 time interval
2332 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2334 # select frames with a minimum distance of 10 seconds
2335 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2338 @section setdar, setsar
2340 The @code{setdar} filter sets the Display Aspect Ratio for the filter
2343 This is done by changing the specified Sample (aka Pixel) Aspect
2344 Ratio, according to the following equation:
2346 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
2349 Keep in mind that the @code{setdar} filter does not modify the pixel
2350 dimensions of the video frame. Also the display aspect ratio set by
2351 this filter may be changed by later filters in the filterchain,
2352 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
2355 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
2356 the filter output video.
2358 Note that as a consequence of the application of this filter, the
2359 output display aspect ratio will change according to the equation
2362 Keep in mind that the sample aspect ratio set by the @code{setsar}
2363 filter may be changed by later filters in the filterchain, e.g. if
2364 another "setsar" or a "setdar" filter is applied.
2366 The @code{setdar} and @code{setsar} filters accept a parameter string
2367 which represents the wanted aspect ratio. The parameter can
2368 be a floating point number string, an expression, or a string of the form
2369 @var{num}:@var{den}, where @var{num} and @var{den} are the numerator
2370 and denominator of the aspect ratio. If the parameter is not
2371 specified, it is assumed the value "0:1".
2373 For example to change the display aspect ratio to 16:9, specify:
2378 The example above is equivalent to:
2383 To change the sample aspect ratio to 10:11, specify:
2390 Force field for the output video frame.
2392 The @code{setfield} filter marks the interlace type field for the
2393 output frames. It does not change the input frame, but only sets the
2394 corresponding property, which affects how the frame is treated by
2395 followig filters (e.g. @code{fieldorder} or @code{yadif}).
2397 It accepts a parameter representing an integer or a string, which can
2398 assume the following values:
2401 Keep the same field property.
2404 Mark the frame as bottom-field-first.
2407 Mark the frame as top-field-first.
2412 Change the PTS (presentation timestamp) of the input video frames.
2414 Accept in input an expression evaluated through the eval API, which
2415 can contain the following constants:
2419 the presentation timestamp in input
2422 the count of the input frame, starting from 0.
2425 the PTS of the first video frame
2428 tell if the current frame is interlaced
2431 original position in the file of the frame, or undefined if undefined
2432 for the current frame
2442 Some examples follow:
2445 # start counting PTS from zero
2457 # fixed rate 25 fps with some jitter
2458 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2463 Set the timebase to use for the output frames timestamps.
2464 It is mainly useful for testing timebase configuration.
2466 It accepts in input an arithmetic expression representing a rational.
2467 The expression can contain the constants "AVTB" (the
2468 default timebase), and "intb" (the input timebase).
2470 The default value for the input is "intb".
2472 Follow some examples.
2475 # set the timebase to 1/25
2478 # set the timebase to 1/10
2481 #set the timebase to 1001/1000
2484 #set the timebase to 2*intb
2487 #set the default timebase value
2493 Show a line containing various information for each input video frame.
2494 The input video is not modified.
2496 The shown line contains a sequence of key/value pairs of the form
2497 @var{key}:@var{value}.
2499 A description of each shown parameter follows:
2503 sequential number of the input frame, starting from 0
2506 Presentation TimeStamp of the input frame, expressed as a number of
2507 time base units. The time base unit depends on the filter input pad.
2510 Presentation TimeStamp of the input frame, expressed as a number of
2514 position of the frame in the input stream, -1 if this information in
2515 unavailable and/or meaningless (for example in case of synthetic video)
2521 sample aspect ratio of the input frame, expressed in the form
2525 size of the input frame, expressed in the form
2526 @var{width}x@var{height}
2529 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2530 for bottom field first)
2533 1 if the frame is a key frame, 0 otherwise
2536 picture type of the input frame ("I" for an I-frame, "P" for a
2537 P-frame, "B" for a B-frame, "?" for unknown type).
2538 Check also the documentation of the @code{AVPictureType} enum and of
2539 the @code{av_get_picture_type_char} function defined in
2540 @file{libavutil/avutil.h}.
2543 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2545 @item plane_checksum
2546 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2547 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2552 Pass the images of input video on to next video filter as multiple
2556 ffmpeg -i in.avi -vf "slicify=32" out.avi
2559 The filter accepts the slice height as parameter. If the parameter is
2560 not specified it will use the default value of 16.
2562 Adding this in the beginning of filter chains should make filtering
2563 faster due to better use of the memory cache.
2567 Pass on the input video to two outputs. Both outputs are identical to
2572 [in] split [splitout1][splitout2];
2573 [splitout1] crop=100:100:0:0 [cropout];
2574 [splitout2] pad=200:200:100:100 [padout];
2577 will create two separate outputs from the same input, one cropped and
2581 Select the most representative frame in a given sequence of consecutive frames.
2583 It accepts as argument the frames batch size to analyze (default @var{N}=100);
2584 in a set of @var{N} frames, the filter will pick one of them, and then handle
2585 the next batch of @var{N} frames until the end.
2587 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
2588 value will result in a higher memory usage, so a high value is not recommended.
2590 The following example extract one picture each 50 frames:
2595 Complete example of a thumbnail creation with @command{ffmpeg}:
2597 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
2602 Perform various types of temporal field interlacing.
2604 Frames are counted starting from 1, so the first input frame is
2607 This filter accepts a single parameter specifying the mode. Available
2612 Move odd frames into the upper field, even into the lower field,
2613 generating a double height frame at half framerate.
2616 Only output even frames, odd frames are dropped, generating a frame with
2617 unchanged height at half framerate.
2620 Only output odd frames, even frames are dropped, generating a frame with
2621 unchanged height at half framerate.
2624 Expand each frame to full height, but pad alternate lines with black,
2625 generating a frame with double height at the same input framerate.
2628 Interleave the upper field from odd frames with the lower field from
2629 even frames, generating a frame with unchanged height at half framerate.
2632 Interleave the lower field from odd frames with the upper field from
2633 even frames, generating a frame with unchanged height at half framerate.
2640 Transpose rows with columns in the input video and optionally flip it.
2642 It accepts a parameter representing an integer, which can assume the
2647 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2655 Rotate by 90 degrees clockwise, that is:
2663 Rotate by 90 degrees counterclockwise, that is:
2671 Rotate by 90 degrees clockwise and vertically flip, that is:
2681 Sharpen or blur the input video.
2683 It accepts the following parameters:
2684 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2686 Negative values for the amount will blur the input video, while positive
2687 values will sharpen. All parameters are optional and default to the
2688 equivalent of the string '5:5:1.0:5:5:0.0'.
2693 Set the luma matrix horizontal size. It can be an integer between 3
2694 and 13, default value is 5.
2697 Set the luma matrix vertical size. It can be an integer between 3
2698 and 13, default value is 5.
2701 Set the luma effect strength. It can be a float number between -2.0
2702 and 5.0, default value is 1.0.
2704 @item chroma_msize_x
2705 Set the chroma matrix horizontal size. It can be an integer between 3
2706 and 13, default value is 5.
2708 @item chroma_msize_y
2709 Set the chroma matrix vertical size. It can be an integer between 3
2710 and 13, default value is 5.
2713 Set the chroma effect strength. It can be a float number between -2.0
2714 and 5.0, default value is 0.0.
2719 # Strong luma sharpen effect parameters
2722 # Strong blur of both luma and chroma parameters
2723 unsharp=7:7:-2:7:7:-2
2725 # Use the default values with @command{ffmpeg}
2726 ffmpeg -i in.avi -vf "unsharp" out.mp4
2731 Flip the input video vertically.
2734 ffmpeg -i in.avi -vf "vflip" out.avi
2739 Deinterlace the input video ("yadif" means "yet another deinterlacing
2742 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2744 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2749 output 1 frame for each frame
2751 output 1 frame for each field
2753 like 0 but skips spatial interlacing check
2755 like 1 but skips spatial interlacing check
2760 @var{parity} specifies the picture field parity assumed for the input
2761 interlaced video, accepts one of the following values:
2765 assume top field first
2767 assume bottom field first
2769 enable automatic detection
2772 Default value is -1.
2773 If interlacing is unknown or decoder does not export this information,
2774 top field first will be assumed.
2776 @var{auto} specifies if deinterlacer should trust the interlaced flag
2777 and only deinterlace frames marked as interlaced
2781 deinterlace all frames
2783 only deinterlace frames marked as interlaced
2788 @c man end VIDEO FILTERS
2790 @chapter Video Sources
2791 @c man begin VIDEO SOURCES
2793 Below is a description of the currently available video sources.
2797 Buffer video frames, and make them available to the filter chain.
2799 This source is mainly intended for a programmatic use, in particular
2800 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2802 It accepts the following parameters:
2803 @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}
2805 All the parameters but @var{scale_params} need to be explicitly
2808 Follows the list of the accepted parameters.
2813 Specify the width and height of the buffered video frames.
2815 @item pix_fmt_string
2816 A string representing the pixel format of the buffered video frames.
2817 It may be a number corresponding to a pixel format, or a pixel format
2820 @item timebase_num, timebase_den
2821 Specify numerator and denomitor of the timebase assumed by the
2822 timestamps of the buffered frames.
2824 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2825 Specify numerator and denominator of the sample aspect ratio assumed
2826 by the video frames.
2829 Specify the optional parameters to be used for the scale filter which
2830 is automatically inserted when an input change is detected in the
2831 input size or format.
2836 buffer=320:240:yuv410p:1:24:1:1
2839 will instruct the source to accept video frames with size 320x240 and
2840 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2841 square pixels (1:1 sample aspect ratio).
2842 Since the pixel format with name "yuv410p" corresponds to the number 6
2843 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2844 this example corresponds to:
2846 buffer=320:240:6:1:24:1:1
2851 Create a pattern generated by an elementary cellular automaton.
2853 The initial state of the cellular automaton can be defined through the
2854 @option{filename}, and @option{pattern} options. If such options are
2855 not specified an initial state is created randomly.
2857 At each new frame a new row in the video is filled with the result of
2858 the cellular automaton next generation. The behavior when the whole
2859 frame is filled is defined by the @option{scroll} option.
2861 This source accepts a list of options in the form of
2862 @var{key}=@var{value} pairs separated by ":". A description of the
2863 accepted options follows.
2867 Read the initial cellular automaton state, i.e. the starting row, from
2869 In the file, each non-whitespace character is considered an alive
2870 cell, a newline will terminate the row, and further characters in the
2871 file will be ignored.
2874 Read the initial cellular automaton state, i.e. the starting row, from
2875 the specified string.
2877 Each non-whitespace character in the string is considered an alive
2878 cell, a newline will terminate the row, and further characters in the
2879 string will be ignored.
2882 Set the video rate, that is the number of frames generated per second.
2885 @item random_fill_ratio, ratio
2886 Set the random fill ratio for the initial cellular automaton row. It
2887 is a floating point number value ranging from 0 to 1, defaults to
2890 This option is ignored when a file or a pattern is specified.
2892 @item random_seed, seed
2893 Set the seed for filling randomly the initial row, must be an integer
2894 included between 0 and UINT32_MAX. If not specified, or if explicitly
2895 set to -1, the filter will try to use a good random seed on a best
2899 Set the cellular automaton rule, it is a number ranging from 0 to 255.
2900 Default value is 110.
2903 Set the size of the output video.
2905 If @option{filename} or @option{pattern} is specified, the size is set
2906 by default to the width of the specified initial state row, and the
2907 height is set to @var{width} * PHI.
2909 If @option{size} is set, it must contain the width of the specified
2910 pattern string, and the specified pattern will be centered in the
2913 If a filename or a pattern string is not specified, the size value
2914 defaults to "320x518" (used for a randomly generated initial state).
2917 If set to 1, scroll the output upward when all the rows in the output
2918 have been already filled. If set to 0, the new generated row will be
2919 written over the top row just after the bottom row is filled.
2922 @item start_full, full
2923 If set to 1, completely fill the output with generated rows before
2924 outputting the first frame.
2925 This is the default behavior, for disabling set the value to 0.
2928 If set to 1, stitch the left and right row edges together.
2929 This is the default behavior, for disabling set the value to 0.
2932 @subsection Examples
2936 Read the initial state from @file{pattern}, and specify an output of
2939 cellauto=f=pattern:s=200x400
2943 Generate a random initial row with a width of 200 cells, with a fill
2946 cellauto=ratio=2/3:s=200x200
2950 Create a pattern generated by rule 18 starting by a single alive cell
2951 centered on an initial row with width 100:
2953 cellauto=p=@@:s=100x400:full=0:rule=18
2957 Specify a more elaborated initial pattern:
2959 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
2966 Provide an uniformly colored input.
2968 It accepts the following parameters:
2969 @var{color}:@var{frame_size}:@var{frame_rate}
2971 Follows the description of the accepted parameters.
2976 Specify the color of the source. It can be the name of a color (case
2977 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2978 alpha specifier. The default value is "black".
2981 Specify the size of the sourced video, it may be a string of the form
2982 @var{width}x@var{height}, or the name of a size abbreviation. The
2983 default value is "320x240".
2986 Specify the frame rate of the sourced video, as the number of frames
2987 generated per second. It has to be a string in the format
2988 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2989 number or a valid video frame rate abbreviation. The default value is
2994 For example the following graph description will generate a red source
2995 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2996 frames per second, which will be overlayed over the source connected
2997 to the pad with identifier "in".
3000 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
3005 Read a video stream from a movie container.
3007 It accepts the syntax: @var{movie_name}[:@var{options}] where
3008 @var{movie_name} is the name of the resource to read (not necessarily
3009 a file but also a device or a stream accessed through some protocol),
3010 and @var{options} is an optional sequence of @var{key}=@var{value}
3011 pairs, separated by ":".
3013 The description of the accepted options follows.
3017 @item format_name, f
3018 Specifies the format assumed for the movie to read, and can be either
3019 the name of a container or an input device. If not specified the
3020 format is guessed from @var{movie_name} or by probing.
3022 @item seek_point, sp
3023 Specifies the seek point in seconds, the frames will be output
3024 starting from this seek point, the parameter is evaluated with
3025 @code{av_strtod} so the numerical value may be suffixed by an IS
3026 postfix. Default value is "0".
3028 @item stream_index, si
3029 Specifies the index of the video stream to read. If the value is -1,
3030 the best suited video stream will be automatically selected. Default
3035 This filter allows to overlay a second video on top of main input of
3036 a filtergraph as shown in this graph:
3038 input -----------> deltapts0 --> overlay --> output
3041 movie --> scale--> deltapts1 -------+
3044 Some examples follow:
3046 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
3047 # on top of the input labelled as "in".
3048 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3049 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3051 # read from a video4linux2 device, and overlay it on top of the input
3053 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3054 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3060 Generate various test patterns, as generated by the MPlayer test filter.
3062 The size of the generated video is fixed, and is 256x256.
3063 This source is useful in particular for testing encoding features.
3065 This source accepts an optional sequence of @var{key}=@var{value} pairs,
3066 separated by ":". The description of the accepted options follows.
3071 Specify the frame rate of the sourced video, as the number of frames
3072 generated per second. It has to be a string in the format
3073 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3074 number or a valid video frame rate abbreviation. The default value is
3078 Set the video duration of the sourced video. The accepted syntax is:
3080 [-]HH[:MM[:SS[.m...]]]
3083 See also the function @code{av_parse_time()}.
3085 If not specified, or the expressed duration is negative, the video is
3086 supposed to be generated forever.
3090 Set the number or the name of the test to perform. Supported tests are:
3105 Default value is "all", which will cycle through the list of all tests.
3108 For example the following:
3113 will generate a "dc_luma" test pattern.
3117 Provide a frei0r source.
3119 To enable compilation of this filter you need to install the frei0r
3120 header and configure FFmpeg with @code{--enable-frei0r}.
3122 The source supports the syntax:
3124 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
3127 @var{size} is the size of the video to generate, may be a string of the
3128 form @var{width}x@var{height} or a frame size abbreviation.
3129 @var{rate} is the rate of the video to generate, may be a string of
3130 the form @var{num}/@var{den} or a frame rate abbreviation.
3131 @var{src_name} is the name to the frei0r source to load. For more
3132 information regarding frei0r and how to set the parameters read the
3133 section @ref{frei0r} in the description of the video filters.
3135 Some examples follow:
3137 # generate a frei0r partik0l source with size 200x200 and frame rate 10
3138 # which is overlayed on the overlay filter main input
3139 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
3144 Generate a life pattern.
3146 This source is based on a generalization of John Conway's life game.
3148 The sourced input represents a life grid, each pixel represents a cell
3149 which can be in one of two possible states, alive or dead. Every cell
3150 interacts with its eight neighbours, which are the cells that are
3151 horizontally, vertically, or diagonally adjacent.
3153 At each interaction the grid evolves according to the adopted rule,
3154 which specifies the number of neighbor alive cells which will make a
3155 cell stay alive or born. The @option{rule} option allows to specify
3158 This source accepts a list of options in the form of
3159 @var{key}=@var{value} pairs separated by ":". A description of the
3160 accepted options follows.
3164 Set the file from which to read the initial grid state. In the file,
3165 each non-whitespace character is considered an alive cell, and newline
3166 is used to delimit the end of each row.
3168 If this option is not specified, the initial grid is generated
3172 Set the video rate, that is the number of frames generated per second.
3175 @item random_fill_ratio, ratio
3176 Set the random fill ratio for the initial random grid. It is a
3177 floating point number value ranging from 0 to 1, defaults to 1/PHI.
3178 It is ignored when a file is specified.
3180 @item random_seed, seed
3181 Set the seed for filling the initial random grid, must be an integer
3182 included between 0 and UINT32_MAX. If not specified, or if explicitly
3183 set to -1, the filter will try to use a good random seed on a best
3189 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
3190 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
3191 @var{NS} specifies the number of alive neighbor cells which make a
3192 live cell stay alive, and @var{NB} the number of alive neighbor cells
3193 which make a dead cell to become alive (i.e. to "born").
3194 "s" and "b" can be used in place of "S" and "B", respectively.
3196 Alternatively a rule can be specified by an 18-bits integer. The 9
3197 high order bits are used to encode the next cell state if it is alive
3198 for each number of neighbor alive cells, the low order bits specify
3199 the rule for "borning" new cells. Higher order bits encode for an
3200 higher number of neighbor cells.
3201 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
3202 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
3204 Default value is "S23/B3", which is the original Conway's game of life
3205 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
3206 cells, and will born a new cell if there are three alive cells around
3210 Set the size of the output video.
3212 If @option{filename} is specified, the size is set by default to the
3213 same size of the input file. If @option{size} is set, it must contain
3214 the size specified in the input file, and the initial grid defined in
3215 that file is centered in the larger resulting area.
3217 If a filename is not specified, the size value defaults to "320x240"
3218 (used for a randomly generated initial grid).
3221 If set to 1, stitch the left and right grid edges together, and the
3222 top and bottom edges also. Defaults to 1.
3225 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
3226 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
3227 value from 0 to 255.
3230 Set the color of living (or new born) cells.
3233 Set the color of dead cells. If @option{mold} is set, this is the first color
3234 used to represent a dead cell.
3237 Set mold color, for definitely dead and moldy cells.
3240 @subsection Examples
3244 Read a grid from @file{pattern}, and center it on a grid of size
3247 life=f=pattern:s=300x300
3251 Generate a random grid of size 200x200, with a fill ratio of 2/3:
3253 life=ratio=2/3:s=200x200
3257 Specify a custom rule for evolving a randomly generated grid:
3263 Full example with slow death effect (mold) using @command{ffplay}:
3265 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
3269 @section nullsrc, rgbtestsrc, testsrc
3271 The @code{nullsrc} source returns unprocessed video frames. It is
3272 mainly useful to be employed in analysis / debugging tools, or as the
3273 source for filters which ignore the input data.
3275 The @code{rgbtestsrc} source generates an RGB test pattern useful for
3276 detecting RGB vs BGR issues. You should see a red, green and blue
3277 stripe from top to bottom.
3279 The @code{testsrc} source generates a test video pattern, showing a
3280 color pattern, a scrolling gradient and a timestamp. This is mainly
3281 intended for testing purposes.
3283 These sources accept an optional sequence of @var{key}=@var{value} pairs,
3284 separated by ":". The description of the accepted options follows.
3289 Specify the size of the sourced video, it may be a string of the form
3290 @var{width}x@var{height}, or the name of a size abbreviation. The
3291 default value is "320x240".
3294 Specify the frame rate of the sourced video, as the number of frames
3295 generated per second. It has to be a string in the format
3296 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3297 number or a valid video frame rate abbreviation. The default value is
3301 Set the sample aspect ratio of the sourced video.
3304 Set the video duration of the sourced video. The accepted syntax is:
3306 [-]HH[:MM[:SS[.m...]]]
3309 See also the function @code{av_parse_time()}.
3311 If not specified, or the expressed duration is negative, the video is
3312 supposed to be generated forever.
3315 Set the number of decimals to show in the timestamp, only used in the
3316 @code{testsrc} source.
3318 The displayed timestamp value will correspond to the original
3319 timestamp value multiplied by the power of 10 of the specified
3320 value. Default value is 0.
3323 For example the following:
3325 testsrc=duration=5.3:size=qcif:rate=10
3328 will generate a video with a duration of 5.3 seconds, with size
3329 176x144 and a frame rate of 10 frames per second.
3331 If the input content is to be ignored, @code{nullsrc} can be used. The
3332 following command generates noise in the luminance plane by employing
3333 the @code{mp=geq} filter:
3335 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
3338 @c man end VIDEO SOURCES
3340 @chapter Video Sinks
3341 @c man begin VIDEO SINKS
3343 Below is a description of the currently available video sinks.
3347 Buffer video frames, and make them available to the end of the filter
3350 This sink is mainly intended for a programmatic use, in particular
3351 through the interface defined in @file{libavfilter/buffersink.h}.
3353 It does not require a string parameter in input, but you need to
3354 specify a pointer to a list of supported pixel formats terminated by
3355 -1 in the opaque parameter provided to @code{avfilter_init_filter}
3356 when initializing this sink.
3360 Null video sink, do absolutely nothing with the input video. It is
3361 mainly useful as a template and to be employed in analysis / debugging
3364 @c man end VIDEO SINKS