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}:@var{packing_format}".
109 @var{sample_format} specifies the sample format, and can be a string or
110 the corresponding numeric value defined in @file{libavutil/samplefmt.h}.
112 @var{channel_layout} specifies the channel layout, and can be a string
113 or the corresponding number value defined in @file{libavutil/audioconvert.h}.
115 @var{packing_format} specifies the type of packing in output, can be one
116 of "planar" or "packed", or the corresponding numeric values "0" or "1".
118 The special parameter "auto", signifies that the filter will
119 automatically select the output format depending on the output filter.
121 Some examples follow.
125 Convert input to unsigned 8-bit, stereo, packed:
127 aconvert=u8:stereo:packed
131 Convert input to unsigned 8-bit, automatically select out channel layout
134 aconvert=u8:auto:auto
140 Convert the input audio to one of the specified formats. The framework will
141 negotiate the most appropriate format to minimize conversions.
143 The filter accepts three lists of formats, separated by ":", in the form:
144 "@var{sample_formats}:@var{channel_layouts}:@var{packing_formats}".
146 Elements in each list are separated by "," which has to be escaped in the
147 filtergraph specification.
149 The special parameter "all", in place of a list of elements, signifies all
152 Some examples follow:
154 aformat=u8\\,s16:mono:packed
156 aformat=s16:mono\\,stereo:all
161 Merge two audio streams into a single multi-channel stream.
163 This filter does not need any argument.
165 If the channel layouts of the inputs are disjoint, and therefore compatible,
166 the channel layout of the output will be set accordingly and the channels
167 will be reordered as necessary. If the channel layouts of the inputs are not
168 disjoint, the output will have all the channels of the first input then all
169 the channels of the second input, in that order, and the channel layout of
170 the output will be the default value corresponding to the total number of
173 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
174 is FC+BL+BR, then the output will be in 5.1, with the channels in the
175 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
176 first input, b1 is the first channel of the second input).
178 On the other hand, if both input are in stereo, the output channels will be
179 in the default order: a1, a2, b1, b2, and the channel layout will be
180 arbitrarily set to 4.0, which may or may not be the expected value.
182 Both inputs must have the same sample rate, format and packing.
184 If inputs do not have the same duration, the output will stop with the
187 Example: merge two mono files into a stereo stream:
189 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
194 Pass the audio source unchanged to the output.
198 Resample the input audio to the specified sample rate.
200 The filter accepts exactly one parameter, the output sample rate. If not
201 specified then the filter will automatically convert between its input
202 and output sample rates.
204 For example, to resample the input audio to 44100Hz:
211 Show a line containing various information for each input audio frame.
212 The input audio is not modified.
214 The shown line contains a sequence of key/value pairs of the form
215 @var{key}:@var{value}.
217 A description of each shown parameter follows:
221 sequential number of the input frame, starting from 0
224 presentation TimeStamp of the input frame, expressed as a number of
225 time base units. The time base unit depends on the filter input pad, and
226 is usually 1/@var{sample_rate}.
229 presentation TimeStamp of the input frame, expressed as a number of
233 position of the frame in the input stream, -1 if this information in
234 unavailable and/or meaningless (for example in case of synthetic audio)
240 channel layout description
243 number of samples (per each channel) contained in the filtered frame
246 sample rate for the audio frame
249 if the packing format is planar, 0 if packed
252 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
255 Adler-32 checksum (printed in hexadecimal) for each input frame plane,
256 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
262 Pass on the input audio to two outputs. Both outputs are identical to
267 [in] asplit[out0], showaudio[out1]
270 will create two separate outputs from the same input, one cropped and
275 Forward two audio streams and control the order the buffers are forwarded.
277 The argument to the filter is an expression deciding which stream should be
278 forwarded next: if the result is negative, the first stream is forwarded; if
279 the result is positive or zero, the second stream is forwarded. It can use
280 the following variables:
284 number of buffers forwarded so far on each stream
286 number of samples forwarded so far on each stream
288 current timestamp of each stream
291 The default value is @code{t1-t2}, which means to always forward the stream
292 that has a smaller timestamp.
294 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
295 input, while avoiding too much of a desynchronization:
297 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
298 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
304 Make audio easier to listen to on headphones.
306 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
307 so that when listened to on headphones the stereo image is moved from
308 inside your head (standard for headphones) to outside and in front of
309 the listener (standard for speakers).
315 Mix channels with specific gain levels. The filter accepts the output
316 channel layout followed by a set of channels definitions.
318 This filter is also designed to remap efficiently the channels of an audio
321 The filter accepts parameters of the form:
322 "@var{l}:@var{outdef}:@var{outdef}:..."
326 output channel layout or number of channels
329 output channel specification, of the form:
330 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
333 output channel to define, either a channel name (FL, FR, etc.) or a channel
334 number (c0, c1, etc.)
337 multiplicative coefficient for the channel, 1 leaving the volume unchanged
340 input channel to use, see out_name for details; it is not possible to mix
341 named and numbered input channels
344 If the `=' in a channel specification is replaced by `<', then the gains for
345 that specification will be renormalized so that the total is 1, thus
346 avoiding clipping noise.
348 @subsection Mixing examples
350 For example, if you want to down-mix from stereo to mono, but with a bigger
351 factor for the left channel:
353 pan=1:c0=0.9*c0+0.1*c1
356 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
359 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
362 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
363 that should be preferred (see "-ac" option) unless you have very specific
366 @subsection Remapping examples
368 The channel remapping will be effective if, and only if:
371 @item gain coefficients are zeroes or ones,
372 @item only one input per channel output,
373 @item the number of output channels is supported by libswresample (16 at the
375 @c if SWR_CH_MAX changes, fix the line above.
378 If all these conditions are satisfied, the filter will notify the user ("Pure
379 channel mapping detected"), and use an optimized and lossless method to do the
382 For example, if you have a 5.1 source and want a stereo audio stream by
383 dropping the extra channels:
385 pan="stereo: c0=FL : c1=FR"
388 Given the same source, you can also switch front left and front right channels
389 and keep the input channel layout:
391 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
394 If the input is a stereo audio stream, you can mute the front left channel (and
395 still keep the stereo channel layout) with:
400 Still with a stereo audio stream input, you can copy the right channel in both
401 front left and right:
403 pan="stereo: c0=FR : c1=FR"
406 @section silencedetect
408 Detect silence in an audio stream.
410 This filter logs a message when it detects that the input audio volume is less
411 or equal to a noise tolerance value for a duration greater or equal to the
412 minimum detected noise duration.
414 The printed times and duration are expressed in seconds.
418 Set silence duration until notification (default is 2 seconds).
421 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
422 specified value) or amplitude ratio. Default is -60dB, or 0.001.
425 Detect 5 seconds of silence with -50dB noise tolerance:
427 silencedetect=n=-50dB:d=5
430 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
431 tolerance in @file{silence.mp3}:
433 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
438 Adjust the input audio volume.
440 The filter accepts exactly one parameter @var{vol}, which expresses
441 how the audio volume will be increased or decreased.
443 Output values are clipped to the maximum value.
445 If @var{vol} is expressed as a decimal number, the output audio
446 volume is given by the relation:
448 @var{output_volume} = @var{vol} * @var{input_volume}
451 If @var{vol} is expressed as a decimal number followed by the string
452 "dB", the value represents the requested change in decibels of the
453 input audio power, and the output audio volume is given by the
456 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
459 Otherwise @var{vol} is considered an expression and its evaluated
460 value is used for computing the output audio volume according to the
463 Default value for @var{vol} is 1.0.
469 Half the input audio volume:
474 The above example is equivalent to:
480 Decrease input audio power by 12 decibels:
486 @c man end AUDIO FILTERS
488 @chapter Audio Sources
489 @c man begin AUDIO SOURCES
491 Below is a description of the currently available audio sources.
495 Buffer audio frames, and make them available to the filter chain.
497 This source is mainly intended for a programmatic use, in particular
498 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
500 It accepts the following mandatory parameters:
501 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
506 The sample rate of the incoming audio buffers.
509 The sample format of the incoming audio buffers.
510 Either a sample format name or its corresponging integer representation from
511 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
514 The channel layout of the incoming audio buffers.
515 Either a channel layout name from channel_layout_map in
516 @file{libavutil/audioconvert.c} or its corresponding integer representation
517 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
520 Either "packed" or "planar", or their integer representation: 0 or 1
527 abuffer=44100:s16:stereo:planar
530 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
531 Since the sample format with name "s16" corresponds to the number
532 1 and the "stereo" channel layout corresponds to the value 3, this is
540 Generate an audio signal specified by an expression.
542 This source accepts in input one or more expressions (one for each
543 channel), which are evaluated and used to generate a corresponding
546 It accepts the syntax: @var{exprs}[::@var{options}].
547 @var{exprs} is a list of expressions separated by ":", one for each
548 separate channel. The output channel layout depends on the number of
549 provided expressions, up to 8 channels are supported.
551 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
554 The description of the accepted options follows.
559 Set the minimum duration of the sourced audio. See the function
560 @code{av_parse_time()} for the accepted format.
561 Note that the resulting duration may be greater than the specified
562 duration, as the generated audio is always cut at the end of a
565 If not specified, or the expressed duration is negative, the audio is
566 supposed to be generated forever.
569 Set the number of samples per channel per each output frame,
573 Specify the sample rate, default to 44100.
576 Each expression in @var{exprs} can contain the following constants:
580 number of the evaluated sample, starting from 0
583 time of the evaluated sample expressed in seconds, starting from 0
602 Generate a sin signal with frequency of 440 Hz, set sample rate to
605 aevalsrc="sin(440*2*PI*t)::s=8000"
609 Generate white noise:
611 aevalsrc="-2+random(0)"
615 Generate an amplitude modulated signal:
617 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
621 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
623 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
630 Read an audio stream from a movie container.
632 It accepts the syntax: @var{movie_name}[:@var{options}] where
633 @var{movie_name} is the name of the resource to read (not necessarily
634 a file but also a device or a stream accessed through some protocol),
635 and @var{options} is an optional sequence of @var{key}=@var{value}
636 pairs, separated by ":".
638 The description of the accepted options follows.
643 Specify the format assumed for the movie to read, and can be either
644 the name of a container or an input device. If not specified the
645 format is guessed from @var{movie_name} or by probing.
648 Specify the seek point in seconds, the frames will be output
649 starting from this seek point, the parameter is evaluated with
650 @code{av_strtod} so the numerical value may be suffixed by an IS
651 postfix. Default value is "0".
653 @item stream_index, si
654 Specify the index of the audio stream to read. If the value is -1,
655 the best suited audio stream will be automatically selected. Default
662 Null audio source, return unprocessed audio frames. It is mainly useful
663 as a template and to be employed in analysis / debugging tools, or as
664 the source for filters which ignore the input data (for example the sox
667 It accepts an optional sequence of @var{key}=@var{value} pairs,
670 The description of the accepted options follows.
675 Specify the sample rate, and defaults to 44100.
677 @item channel_layout, cl
679 Specify the channel layout, and can be either an integer or a string
680 representing a channel layout. The default value of @var{channel_layout}
683 Check the channel_layout_map definition in
684 @file{libavcodec/audioconvert.c} for the mapping between strings and
685 channel layout values.
688 Set the number of samples per requested frames.
692 Follow some examples:
694 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
695 anullsrc=r=48000:cl=4
698 anullsrc=r=48000:cl=mono
701 @c man end AUDIO SOURCES
704 @c man begin AUDIO SINKS
706 Below is a description of the currently available audio sinks.
710 Buffer audio frames, and make them available to the end of filter chain.
712 This sink is mainly intended for programmatic use, in particular
713 through the interface defined in @file{libavfilter/buffersink.h}.
715 It requires a pointer to an AVABufferSinkContext structure, which
716 defines the incoming buffers' formats, to be passed as the opaque
717 parameter to @code{avfilter_init_filter} for initialization.
721 Null audio sink, do absolutely nothing with the input audio. It is
722 mainly useful as a template and to be employed in analysis / debugging
725 @c man end AUDIO SINKS
727 @chapter Video Filters
728 @c man begin VIDEO FILTERS
730 When you configure your FFmpeg build, you can disable any of the
731 existing filters using @code{--disable-filters}.
732 The configure output will show the video filters included in your
735 Below is a description of the currently available video filters.
739 Draw ASS (Advanced Substation Alpha) subtitles on top of input video
740 using the libass library.
742 To enable compilation of this filter you need to configure FFmpeg with
743 @code{--enable-libass}.
745 This filter accepts in input the name of the ass file to render.
747 For example, to render the file @file{sub.ass} on top of the input
748 video, use the command:
755 Detect frames that are (almost) completely black. Can be useful to
756 detect chapter transitions or commercials. Output lines consist of
757 the frame number of the detected frame, the percentage of blackness,
758 the position in the file if known or -1 and the timestamp in seconds.
760 In order to display the output lines, you need to set the loglevel at
761 least to the AV_LOG_INFO value.
763 The filter accepts the syntax:
765 blackframe[=@var{amount}:[@var{threshold}]]
768 @var{amount} is the percentage of the pixels that have to be below the
769 threshold, and defaults to 98.
771 @var{threshold} is the threshold below which a pixel value is
772 considered black, and defaults to 32.
776 Apply boxblur algorithm to the input video.
778 This filter accepts the parameters:
779 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
781 Chroma and alpha parameters are optional, if not specified they default
782 to the corresponding values set for @var{luma_radius} and
785 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
786 the radius in pixels of the box used for blurring the corresponding
787 input plane. They are expressions, and can contain the following
791 the input width and height in pixels
794 the input chroma image width and height in pixels
797 horizontal and vertical chroma subsample values. For example for the
798 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
801 The radius must be a non-negative number, and must not be greater than
802 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
803 and of @code{min(cw,ch)/2} for the chroma planes.
805 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
806 how many times the boxblur filter is applied to the corresponding
809 Some examples follow:
814 Apply a boxblur filter with luma, chroma, and alpha radius
821 Set luma radius to 2, alpha and chroma radius to 0
827 Set luma and chroma radius to a fraction of the video dimension
829 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
836 Copy the input source unchanged to the output. Mainly useful for
841 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
843 The parameters are expressions containing the following constants:
847 the computed values for @var{x} and @var{y}. They are evaluated for
851 the input width and height
854 same as @var{in_w} and @var{in_h}
857 the output (cropped) width and height
860 same as @var{out_w} and @var{out_h}
863 same as @var{iw} / @var{ih}
866 input sample aspect ratio
869 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
872 horizontal and vertical chroma subsample values. For example for the
873 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
876 the number of input frame, starting from 0
879 the position in the file of the input frame, NAN if unknown
882 timestamp expressed in seconds, NAN if the input timestamp is unknown
886 The @var{out_w} and @var{out_h} parameters specify the expressions for
887 the width and height of the output (cropped) video. They are
888 evaluated just at the configuration of the filter.
890 The default value of @var{out_w} is "in_w", and the default value of
891 @var{out_h} is "in_h".
893 The expression for @var{out_w} may depend on the value of @var{out_h},
894 and the expression for @var{out_h} may depend on @var{out_w}, but they
895 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
896 evaluated after @var{out_w} and @var{out_h}.
898 The @var{x} and @var{y} parameters specify the expressions for the
899 position of the top-left corner of the output (non-cropped) area. They
900 are evaluated for each frame. If the evaluated value is not valid, it
901 is approximated to the nearest valid value.
903 The default value of @var{x} is "(in_w-out_w)/2", and the default
904 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
905 the center of the input image.
907 The expression for @var{x} may depend on @var{y}, and the expression
908 for @var{y} may depend on @var{x}.
910 Follow some examples:
912 # crop the central input area with size 100x100
915 # crop the central input area with size 2/3 of the input video
916 "crop=2/3*in_w:2/3*in_h"
918 # crop the input video central square
921 # delimit the rectangle with the top-left corner placed at position
922 # 100:100 and the right-bottom corner corresponding to the right-bottom
923 # corner of the input image.
924 crop=in_w-100:in_h-100:100:100
926 # crop 10 pixels from the left and right borders, and 20 pixels from
927 # the top and bottom borders
928 "crop=in_w-2*10:in_h-2*20"
930 # keep only the bottom right quarter of the input image
931 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
933 # crop height for getting Greek harmony
934 "crop=in_w:1/PHI*in_w"
937 "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)"
939 # erratic camera effect depending on timestamp
940 "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)"
942 # set x depending on the value of y
943 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
948 Auto-detect crop size.
950 Calculate necessary cropping parameters and prints the recommended
951 parameters through the logging system. The detected dimensions
952 correspond to the non-black area of the input video.
954 It accepts the syntax:
956 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
962 Threshold, which can be optionally specified from nothing (0) to
963 everything (255), defaults to 24.
966 Value which the width/height should be divisible by, defaults to
967 16. The offset is automatically adjusted to center the video. Use 2 to
968 get only even dimensions (needed for 4:2:2 video). 16 is best when
969 encoding to most video codecs.
972 Counter that determines after how many frames cropdetect will reset
973 the previously detected largest video area and start over to detect
974 the current optimal crop area. Defaults to 0.
976 This can be useful when channel logos distort the video area. 0
977 indicates never reset and return the largest area encountered during
983 Suppress a TV station logo by a simple interpolation of the surrounding
984 pixels. Just set a rectangle covering the logo and watch it disappear
985 (and sometimes something even uglier appear - your mileage may vary).
987 The filter accepts parameters as a string of the form
988 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
989 @var{key}=@var{value} pairs, separated by ":".
991 The description of the accepted parameters follows.
996 Specify the top left corner coordinates of the logo. They must be
1000 Specify the width and height of the logo to clear. They must be
1004 Specify the thickness of the fuzzy edge of the rectangle (added to
1005 @var{w} and @var{h}). The default value is 4.
1008 When set to 1, a green rectangle is drawn on the screen to simplify
1009 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1010 @var{band} is set to 4. The default value is 0.
1014 Some examples follow.
1019 Set a rectangle covering the area with top left corner coordinates 0,0
1020 and size 100x77, setting a band of size 10:
1022 delogo=0:0:100:77:10
1026 As the previous example, but use named options:
1028 delogo=x=0:y=0:w=100:h=77:band=10
1035 Attempt to fix small changes in horizontal and/or vertical shift. This
1036 filter helps remove camera shake from hand-holding a camera, bumping a
1037 tripod, moving on a vehicle, etc.
1039 The filter accepts parameters as a string of the form
1040 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1042 A description of the accepted parameters follows.
1047 Specify a rectangular area where to limit the search for motion
1049 If desired the search for motion vectors can be limited to a
1050 rectangular area of the frame defined by its top left corner, width
1051 and height. These parameters have the same meaning as the drawbox
1052 filter which can be used to visualise the position of the bounding
1055 This is useful when simultaneous movement of subjects within the frame
1056 might be confused for camera motion by the motion vector search.
1058 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1059 then the full frame is used. This allows later options to be set
1060 without specifying the bounding box for the motion vector search.
1062 Default - search the whole frame.
1065 Specify the maximum extent of movement in x and y directions in the
1066 range 0-64 pixels. Default 16.
1069 Specify how to generate pixels to fill blanks at the edge of the
1070 frame. An integer from 0 to 3 as follows:
1073 Fill zeroes at blank locations
1075 Original image at blank locations
1077 Extruded edge value at blank locations
1079 Mirrored edge at blank locations
1082 The default setting is mirror edge at blank locations.
1085 Specify the blocksize to use for motion search. Range 4-128 pixels,
1089 Specify the contrast threshold for blocks. Only blocks with more than
1090 the specified contrast (difference between darkest and lightest
1091 pixels) will be considered. Range 1-255, default 125.
1094 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1095 search. Default - exhaustive search.
1098 If set then a detailed log of the motion search is written to the
1105 Draw a colored box on the input image.
1107 It accepts the syntax:
1109 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
1115 Specify the top left corner coordinates of the box. Default to 0.
1118 Specify the width and height of the box, if 0 they are interpreted as
1119 the input width and height. Default to 0.
1122 Specify the color of the box to write, it can be the name of a color
1123 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1126 Follow some examples:
1128 # draw a black box around the edge of the input image
1131 # draw a box with color red and an opacity of 50%
1132 drawbox=10:20:200:60:red@@0.5"
1137 Draw text string or text from specified file on top of video using the
1138 libfreetype library.
1140 To enable compilation of this filter you need to configure FFmpeg with
1141 @code{--enable-libfreetype}.
1143 The filter also recognizes strftime() sequences in the provided text
1144 and expands them accordingly. Check the documentation of strftime().
1146 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1149 The description of the accepted parameters follows.
1154 The font file to be used for drawing text. Path must be included.
1155 This parameter is mandatory.
1158 The text string to be drawn. The text must be a sequence of UTF-8
1160 This parameter is mandatory if no file is specified with the parameter
1164 A text file containing text to be drawn. The text must be a sequence
1165 of UTF-8 encoded characters.
1167 This parameter is mandatory if no text string is specified with the
1168 parameter @var{text}.
1170 If both text and textfile are specified, an error is thrown.
1173 The expressions which specify the offsets where text will be drawn
1174 within the video frame. They are relative to the top/left border of the
1177 The default value of @var{x} and @var{y} is "0".
1179 See below for the list of accepted constants.
1182 The font size to be used for drawing text.
1183 The default value of @var{fontsize} is 16.
1186 The color to be used for drawing fonts.
1187 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1188 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1189 The default value of @var{fontcolor} is "black".
1192 The color to be used for drawing box around text.
1193 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1194 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1195 The default value of @var{boxcolor} is "white".
1198 Used to draw a box around text using background color.
1199 Value should be either 1 (enable) or 0 (disable).
1200 The default value of @var{box} is 0.
1202 @item shadowx, shadowy
1203 The x and y offsets for the text shadow position with respect to the
1204 position of the text. They can be either positive or negative
1205 values. Default value for both is "0".
1208 The color to be used for drawing a shadow behind the drawn text. It
1209 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1210 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1211 The default value of @var{shadowcolor} is "black".
1214 Flags to be used for loading the fonts.
1216 The flags map the corresponding flags supported by libfreetype, and are
1217 a combination of the following values:
1224 @item vertical_layout
1225 @item force_autohint
1228 @item ignore_global_advance_width
1230 @item ignore_transform
1237 Default value is "render".
1239 For more information consult the documentation for the FT_LOAD_*
1243 The size in number of spaces to use for rendering the tab.
1247 The parameters for @var{x} and @var{y} are expressions containing the
1248 following constants:
1252 the input width and height
1255 the width of the rendered text
1258 the height of the rendered text
1261 the height of each text line
1264 input sample aspect ratio
1267 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1270 horizontal and vertical chroma subsample values. For example for the
1271 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1274 maximum glyph width, that is the maximum width for all the glyphs
1275 contained in the rendered text
1278 maximum glyph height, that is the maximum height for all the glyphs
1279 contained in the rendered text, it is equivalent to @var{ascent} -
1282 @item max_glyph_a, ascent
1284 the maximum distance from the baseline to the highest/upper grid
1285 coordinate used to place a glyph outline point, for all the rendered
1287 It is a positive value, due to the grid's orientation with the Y axis
1290 @item max_glyph_d, descent
1291 the maximum distance from the baseline to the lowest grid coordinate
1292 used to place a glyph outline point, for all the rendered glyphs.
1293 This is a negative value, due to the grid's orientation, with the Y axis
1297 the number of input frame, starting from 0
1300 timestamp expressed in seconds, NAN if the input timestamp is unknown
1303 initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
1304 with or without text parameter. @var{rate} option must be specified.
1307 frame rate (timecode only)
1310 Some examples follow.
1315 Draw "Test Text" with font FreeSerif, using the default values for the
1316 optional parameters.
1319 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1323 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1324 and y=50 (counting from the top-left corner of the screen), text is
1325 yellow with a red box around it. Both the text and the box have an
1329 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1330 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1333 Note that the double quotes are not necessary if spaces are not used
1334 within the parameter list.
1337 Show the text at the center of the video frame:
1339 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1343 Show a text line sliding from right to left in the last row of the video
1344 frame. The file @file{LONG_LINE} is assumed to contain a single line
1347 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1351 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1353 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1357 Draw a single green letter "g", at the center of the input video.
1358 The glyph baseline is placed at half screen height.
1360 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1365 For more information about libfreetype, check:
1366 @url{http://www.freetype.org/}.
1370 Apply fade-in/out effect to input video.
1372 It accepts the parameters:
1373 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1375 @var{type} specifies if the effect type, can be either "in" for
1376 fade-in, or "out" for a fade-out effect.
1378 @var{start_frame} specifies the number of the start frame for starting
1379 to apply the fade effect.
1381 @var{nb_frames} specifies the number of frames for which the fade
1382 effect has to last. At the end of the fade-in effect the output video
1383 will have the same intensity as the input video, at the end of the
1384 fade-out transition the output video will be completely black.
1386 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1387 separated by ":". The description of the accepted options follows.
1394 @item start_frame, s
1395 See @var{start_frame}.
1398 See @var{nb_frames}.
1401 If set to 1, fade only alpha channel, if one exists on the input.
1405 A few usage examples follow, usable too as test scenarios.
1407 # fade in first 30 frames of video
1410 # fade out last 45 frames of a 200-frame video
1413 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1414 fade=in:0:25, fade=out:975:25
1416 # make first 5 frames black, then fade in from frame 5-24
1419 # fade in alpha over first 25 frames of video
1420 fade=in:0:25:alpha=1
1425 Transform the field order of the input video.
1427 It accepts one parameter which specifies the required field order that
1428 the input interlaced video will be transformed to. The parameter can
1429 assume one of the following values:
1433 output bottom field first
1435 output top field first
1438 Default value is "tff".
1440 Transformation is achieved by shifting the picture content up or down
1441 by one line, and filling the remaining line with appropriate picture content.
1442 This method is consistent with most broadcast field order converters.
1444 If the input video is not flagged as being interlaced, or it is already
1445 flagged as being of the required output field order then this filter does
1446 not alter the incoming video.
1448 This filter is very useful when converting to or from PAL DV material,
1449 which is bottom field first.
1453 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1458 Buffer input images and send them when they are requested.
1460 This filter is mainly useful when auto-inserted by the libavfilter
1463 The filter does not take parameters.
1467 Convert the input video to one of the specified pixel formats.
1468 Libavfilter will try to pick one that is supported for the input to
1471 The filter accepts a list of pixel format names, separated by ":",
1472 for example "yuv420p:monow:rgb24".
1474 Some examples follow:
1476 # convert the input video to the format "yuv420p"
1479 # convert the input video to any of the formats in the list
1480 format=yuv420p:yuv444p:yuv410p
1486 Apply a frei0r effect to the input video.
1488 To enable compilation of this filter you need to install the frei0r
1489 header and configure FFmpeg with @code{--enable-frei0r}.
1491 The filter supports the syntax:
1493 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1496 @var{filter_name} is the name to the frei0r effect to load. If the
1497 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1498 is searched in each one of the directories specified by the colon
1499 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1500 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1501 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1503 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1504 for the frei0r effect.
1506 A frei0r effect parameter can be a boolean (whose values are specified
1507 with "y" and "n"), a double, a color (specified by the syntax
1508 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1509 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1510 description), a position (specified by the syntax @var{X}/@var{Y},
1511 @var{X} and @var{Y} being float numbers) and a string.
1513 The number and kind of parameters depend on the loaded effect. If an
1514 effect parameter is not specified the default value is set.
1516 Some examples follow:
1518 # apply the distort0r effect, set the first two double parameters
1519 frei0r=distort0r:0.5:0.01
1521 # apply the colordistance effect, takes a color as first parameter
1522 frei0r=colordistance:0.2/0.3/0.4
1523 frei0r=colordistance:violet
1524 frei0r=colordistance:0x112233
1526 # apply the perspective effect, specify the top left and top right
1528 frei0r=perspective:0.2/0.2:0.8/0.2
1531 For more information see:
1532 @url{http://piksel.org/frei0r}
1536 Fix the banding artifacts that are sometimes introduced into nearly flat
1537 regions by truncation to 8bit color depth.
1538 Interpolate the gradients that should go where the bands are, and
1541 This filter is designed for playback only. Do not use it prior to
1542 lossy compression, because compression tends to lose the dither and
1543 bring back the bands.
1545 The filter takes two optional parameters, separated by ':':
1546 @var{strength}:@var{radius}
1548 @var{strength} is the maximum amount by which the filter will change
1549 any one pixel. Also the threshold for detecting nearly flat
1550 regions. Acceptable values range from .51 to 255, default value is
1551 1.2, out-of-range values will be clipped to the valid range.
1553 @var{radius} is the neighborhood to fit the gradient to. A larger
1554 radius makes for smoother gradients, but also prevents the filter from
1555 modifying the pixels near detailed regions. Acceptable values are
1556 8-32, default value is 16, out-of-range values will be clipped to the
1560 # default parameters
1569 Flip the input video horizontally.
1571 For example to horizontally flip the input video with @command{ffmpeg}:
1573 ffmpeg -i in.avi -vf "hflip" out.avi
1578 High precision/quality 3d denoise filter. This filter aims to reduce
1579 image noise producing smooth images and making still images really
1580 still. It should enhance compressibility.
1582 It accepts the following optional parameters:
1583 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1587 a non-negative float number which specifies spatial luma strength,
1590 @item chroma_spatial
1591 a non-negative float number which specifies spatial chroma strength,
1592 defaults to 3.0*@var{luma_spatial}/4.0
1595 a float number which specifies luma temporal strength, defaults to
1596 6.0*@var{luma_spatial}/4.0
1599 a float number which specifies chroma temporal strength, defaults to
1600 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1603 @section lut, lutrgb, lutyuv
1605 Compute a look-up table for binding each pixel component input value
1606 to an output value, and apply it to input video.
1608 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1609 to an RGB input video.
1611 These filters accept in input a ":"-separated list of options, which
1612 specify the expressions used for computing the lookup table for the
1613 corresponding pixel component values.
1615 The @var{lut} filter requires either YUV or RGB pixel formats in
1616 input, and accepts the options:
1619 first pixel component
1621 second pixel component
1623 third pixel component
1625 fourth pixel component, corresponds to the alpha component
1628 The exact component associated to each option depends on the format in
1631 The @var{lutrgb} filter requires RGB pixel formats in input, and
1632 accepts the options:
1644 The @var{lutyuv} filter requires YUV pixel formats in input, and
1645 accepts the options:
1648 Y/luminance component
1657 The expressions can contain the following constants and functions:
1661 the input width and height
1664 input value for the pixel component
1667 the input value clipped in the @var{minval}-@var{maxval} range
1670 maximum value for the pixel component
1673 minimum value for the pixel component
1676 the negated value for the pixel component value clipped in the
1677 @var{minval}-@var{maxval} range , it corresponds to the expression
1678 "maxval-clipval+minval"
1681 the computed value in @var{val} clipped in the
1682 @var{minval}-@var{maxval} range
1684 @item gammaval(gamma)
1685 the computed gamma correction value of the pixel component value
1686 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1688 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1692 All expressions default to "val".
1694 Some examples follow:
1696 # negate input video
1697 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1698 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1700 # the above is the same as
1701 lutrgb="r=negval:g=negval:b=negval"
1702 lutyuv="y=negval:u=negval:v=negval"
1707 # remove chroma components, turns the video into a graytone image
1708 lutyuv="u=128:v=128"
1710 # apply a luma burning effect
1713 # remove green and blue components
1716 # set a constant alpha channel value on input
1717 format=rgba,lutrgb=a="maxval-minval/2"
1719 # correct luminance gamma by a 0.5 factor
1720 lutyuv=y=gammaval(0.5)
1725 Apply an MPlayer filter to the input video.
1727 This filter provides a wrapper around most of the filters of
1730 This wrapper is considered experimental. Some of the wrapped filters
1731 may not work properly and we may drop support for them, as they will
1732 be implemented natively into FFmpeg. Thus you should avoid
1733 depending on them when writing portable scripts.
1735 The filters accepts the parameters:
1736 @var{filter_name}[:=]@var{filter_params}
1738 @var{filter_name} is the name of a supported MPlayer filter,
1739 @var{filter_params} is a string containing the parameters accepted by
1742 The list of the currently supported filters follows:
1796 The parameter syntax and behavior for the listed filters are the same
1797 of the corresponding MPlayer filters. For detailed instructions check
1798 the "VIDEO FILTERS" section in the MPlayer manual.
1800 Some examples follow:
1802 # remove a logo by interpolating the surrounding pixels
1803 mp=delogo=200:200:80:20:1
1805 # adjust gamma, brightness, contrast
1808 # tweak hue and saturation
1812 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1818 This filter accepts an integer in input, if non-zero it negates the
1819 alpha component (if available). The default value in input is 0.
1823 Force libavfilter not to use any of the specified pixel formats for the
1824 input to the next filter.
1826 The filter accepts a list of pixel format names, separated by ":",
1827 for example "yuv420p:monow:rgb24".
1829 Some examples follow:
1831 # force libavfilter to use a format different from "yuv420p" for the
1832 # input to the vflip filter
1833 noformat=yuv420p,vflip
1835 # convert the input video to any of the formats not contained in the list
1836 noformat=yuv420p:yuv444p:yuv410p
1841 Pass the video source unchanged to the output.
1845 Apply video transform using libopencv.
1847 To enable this filter install libopencv library and headers and
1848 configure FFmpeg with @code{--enable-libopencv}.
1850 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1852 @var{filter_name} is the name of the libopencv filter to apply.
1854 @var{filter_params} specifies the parameters to pass to the libopencv
1855 filter. If not specified the default values are assumed.
1857 Refer to the official libopencv documentation for more precise
1859 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1861 Follows the list of supported libopencv filters.
1866 Dilate an image by using a specific structuring element.
1867 This filter corresponds to the libopencv function @code{cvDilate}.
1869 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1871 @var{struct_el} represents a structuring element, and has the syntax:
1872 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1874 @var{cols} and @var{rows} represent the number of columns and rows of
1875 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1876 point, and @var{shape} the shape for the structuring element, and
1877 can be one of the values "rect", "cross", "ellipse", "custom".
1879 If the value for @var{shape} is "custom", it must be followed by a
1880 string of the form "=@var{filename}". The file with name
1881 @var{filename} is assumed to represent a binary image, with each
1882 printable character corresponding to a bright pixel. When a custom
1883 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1884 or columns and rows of the read file are assumed instead.
1886 The default value for @var{struct_el} is "3x3+0x0/rect".
1888 @var{nb_iterations} specifies the number of times the transform is
1889 applied to the image, and defaults to 1.
1891 Follow some example:
1893 # use the default values
1896 # dilate using a structuring element with a 5x5 cross, iterate two times
1897 ocv=dilate=5x5+2x2/cross:2
1899 # read the shape from the file diamond.shape, iterate two times
1900 # the file diamond.shape may contain a pattern of characters like this:
1906 # the specified cols and rows are ignored (but not the anchor point coordinates)
1907 ocv=0x0+2x2/custom=diamond.shape:2
1912 Erode an image by using a specific structuring element.
1913 This filter corresponds to the libopencv function @code{cvErode}.
1915 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1916 with the same syntax and semantics as the @ref{dilate} filter.
1920 Smooth the input video.
1922 The filter takes the following parameters:
1923 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1925 @var{type} is the type of smooth filter to apply, and can be one of
1926 the following values: "blur", "blur_no_scale", "median", "gaussian",
1927 "bilateral". The default value is "gaussian".
1929 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1930 parameters whose meanings depend on smooth type. @var{param1} and
1931 @var{param2} accept integer positive values or 0, @var{param3} and
1932 @var{param4} accept float values.
1934 The default value for @var{param1} is 3, the default value for the
1935 other parameters is 0.
1937 These parameters correspond to the parameters assigned to the
1938 libopencv function @code{cvSmooth}.
1943 Overlay one video on top of another.
1945 It takes two inputs and one output, the first input is the "main"
1946 video on which the second input is overlayed.
1948 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
1950 @var{x} is the x coordinate of the overlayed video on the main video,
1951 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
1952 the following parameters:
1955 @item main_w, main_h
1956 main input width and height
1959 same as @var{main_w} and @var{main_h}
1961 @item overlay_w, overlay_h
1962 overlay input width and height
1965 same as @var{overlay_w} and @var{overlay_h}
1968 @var{options} is an optional list of @var{key}=@var{value} pairs,
1971 The description of the accepted options follows.
1975 If set to 1, force the filter to accept inputs in the RGB
1976 color space. Default value is 0.
1979 Be aware that frames are taken from each input video in timestamp
1980 order, hence, if their initial timestamps differ, it is a a good idea
1981 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1982 have them begin in the same zero timestamp, as it does the example for
1983 the @var{movie} filter.
1985 Follow some examples:
1987 # draw the overlay at 10 pixels from the bottom right
1988 # corner of the main video.
1989 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1991 # insert a transparent PNG logo in the bottom left corner of the input
1992 movie=logo.png [logo];
1993 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1995 # insert 2 different transparent PNG logos (second logo on bottom
1997 movie=logo1.png [logo1];
1998 movie=logo2.png [logo2];
1999 [in][logo1] overlay=10:H-h-10 [in+logo1];
2000 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
2002 # add a transparent color layer on top of the main video,
2003 # WxH specifies the size of the main input to the overlay filter
2004 color=red@.3:WxH [over]; [in][over] overlay [out]
2007 You can chain together more overlays but the efficiency of such
2008 approach is yet to be tested.
2012 Add paddings to the input image, and places the original input at the
2013 given coordinates @var{x}, @var{y}.
2015 It accepts the following parameters:
2016 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
2018 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
2019 expressions containing the following constants:
2023 the input video width and height
2026 same as @var{in_w} and @var{in_h}
2029 the output width and height, that is the size of the padded area as
2030 specified by the @var{width} and @var{height} expressions
2033 same as @var{out_w} and @var{out_h}
2036 x and y offsets as specified by the @var{x} and @var{y}
2037 expressions, or NAN if not yet specified
2040 same as @var{iw} / @var{ih}
2043 input sample aspect ratio
2046 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2049 horizontal and vertical chroma subsample values. For example for the
2050 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2053 Follows the description of the accepted parameters.
2058 Specify the size of the output image with the paddings added. If the
2059 value for @var{width} or @var{height} is 0, the corresponding input size
2060 is used for the output.
2062 The @var{width} expression can reference the value set by the
2063 @var{height} expression, and vice versa.
2065 The default value of @var{width} and @var{height} is 0.
2069 Specify the offsets where to place the input image in the padded area
2070 with respect to the top/left border of the output image.
2072 The @var{x} expression can reference the value set by the @var{y}
2073 expression, and vice versa.
2075 The default value of @var{x} and @var{y} is 0.
2079 Specify the color of the padded area, it can be the name of a color
2080 (case insensitive match) or a 0xRRGGBB[AA] sequence.
2082 The default value of @var{color} is "black".
2086 Some examples follow:
2089 # Add paddings with color "violet" to the input video. Output video
2090 # size is 640x480, the top-left corner of the input video is placed at
2092 pad=640:480:0:40:violet
2094 # pad the input to get an output with dimensions increased bt 3/2,
2095 # and put the input video at the center of the padded area
2096 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2098 # pad the input to get a squared output with size equal to the maximum
2099 # value between the input width and height, and put the input video at
2100 # the center of the padded area
2101 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2103 # pad the input to get a final w/h ratio of 16:9
2104 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2106 # for anamorphic video, in order to set the output display aspect ratio,
2107 # it is necessary to use sar in the expression, according to the relation:
2108 # (ih * X / ih) * sar = output_dar
2109 # X = output_dar / sar
2110 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
2112 # double output size and put the input video in the bottom-right
2113 # corner of the output padded area
2114 pad="2*iw:2*ih:ow-iw:oh-ih"
2117 @section pixdesctest
2119 Pixel format descriptor test filter, mainly useful for internal
2120 testing. The output video should be equal to the input video.
2124 format=monow, pixdesctest
2127 can be used to test the monowhite pixel format descriptor definition.
2131 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
2133 The parameters @var{width} and @var{height} are expressions containing
2134 the following constants:
2138 the input width and height
2141 same as @var{in_w} and @var{in_h}
2144 the output (cropped) width and height
2147 same as @var{out_w} and @var{out_h}
2150 same as @var{iw} / @var{ih}
2153 input sample aspect ratio
2156 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2159 horizontal and vertical chroma subsample values. For example for the
2160 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2163 If the input image format is different from the format requested by
2164 the next filter, the scale filter will convert the input to the
2167 If the value for @var{width} or @var{height} is 0, the respective input
2168 size is used for the output.
2170 If the value for @var{width} or @var{height} is -1, the scale filter will
2171 use, for the respective output size, a value that maintains the aspect
2172 ratio of the input image.
2174 The default value of @var{width} and @var{height} is 0.
2176 Valid values for the optional parameter @var{interl} are:
2180 force interlaced aware scaling
2183 select interlaced aware scaling depending on whether the source frames
2184 are flagged as interlaced or not
2187 Some examples follow:
2189 # scale the input video to a size of 200x100.
2192 # scale the input to 2x
2194 # the above is the same as
2197 # scale the input to half size
2200 # increase the width, and set the height to the same size
2203 # seek for Greek harmony
2207 # increase the height, and set the width to 3/2 of the height
2210 # increase the size, but make the size a multiple of the chroma
2211 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2213 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2214 scale='min(500\, iw*3/2):-1'
2218 Select frames to pass in output.
2220 It accepts in input an expression, which is evaluated for each input
2221 frame. If the expression is evaluated to a non-zero value, the frame
2222 is selected and passed to the output, otherwise it is discarded.
2224 The expression can contain the following constants:
2228 the sequential number of the filtered frame, starting from 0
2231 the sequential number of the selected frame, starting from 0
2233 @item prev_selected_n
2234 the sequential number of the last selected frame, NAN if undefined
2237 timebase of the input timestamps
2240 the PTS (Presentation TimeStamp) of the filtered video frame,
2241 expressed in @var{TB} units, NAN if undefined
2244 the PTS (Presentation TimeStamp) of the filtered video frame,
2245 expressed in seconds, NAN if undefined
2248 the PTS of the previously filtered video frame, NAN if undefined
2250 @item prev_selected_pts
2251 the PTS of the last previously filtered video frame, NAN if undefined
2253 @item prev_selected_t
2254 the PTS of the last previously selected video frame, NAN if undefined
2257 the PTS of the first video frame in the video, NAN if undefined
2260 the time of the first video frame in the video, NAN if undefined
2263 the type of the filtered frame, can assume one of the following
2275 @item interlace_type
2276 the frame interlace type, can assume one of the following values:
2279 the frame is progressive (not interlaced)
2281 the frame is top-field-first
2283 the frame is bottom-field-first
2287 1 if the filtered frame is a key-frame, 0 otherwise
2290 the position in the file of the filtered frame, -1 if the information
2291 is not available (e.g. for synthetic video)
2294 The default value of the select expression is "1".
2296 Some examples follow:
2299 # select all frames in input
2302 # the above is the same as:
2308 # select only I-frames
2309 select='eq(pict_type\,I)'
2311 # select one frame every 100
2312 select='not(mod(n\,100))'
2314 # select only frames contained in the 10-20 time interval
2315 select='gte(t\,10)*lte(t\,20)'
2317 # select only I frames contained in the 10-20 time interval
2318 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2320 # select frames with a minimum distance of 10 seconds
2321 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2327 Set the Display Aspect Ratio for the filter output video.
2329 This is done by changing the specified Sample (aka Pixel) Aspect
2330 Ratio, according to the following equation:
2331 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2333 Keep in mind that this filter does not modify the pixel dimensions of
2334 the video frame. Also the display aspect ratio set by this filter may
2335 be changed by later filters in the filterchain, e.g. in case of
2336 scaling or if another "setdar" or a "setsar" filter is applied.
2338 The filter accepts a parameter string which represents the wanted
2339 display aspect ratio.
2340 The parameter can be a floating point number string, or an expression
2341 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2342 numerator and denominator of the aspect ratio.
2343 If the parameter is not specified, it is assumed the value "0:1".
2345 For example to change the display aspect ratio to 16:9, specify:
2348 # the above is equivalent to
2352 See also the @ref{setsar} filter documentation.
2356 Change the PTS (presentation timestamp) of the input video frames.
2358 Accept in input an expression evaluated through the eval API, which
2359 can contain the following constants:
2363 the presentation timestamp in input
2366 the count of the input frame, starting from 0.
2369 the PTS of the first video frame
2372 tell if the current frame is interlaced
2375 original position in the file of the frame, or undefined if undefined
2376 for the current frame
2386 Some examples follow:
2389 # start counting PTS from zero
2401 # fixed rate 25 fps with some jitter
2402 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2408 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2410 Note that as a consequence of the application of this filter, the
2411 output display aspect ratio will change according to the following
2413 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2415 Keep in mind that the sample aspect ratio set by this filter may be
2416 changed by later filters in the filterchain, e.g. if another "setsar"
2417 or a "setdar" filter is applied.
2419 The filter accepts a parameter string which represents the wanted
2420 sample aspect ratio.
2421 The parameter can be a floating point number string, or an expression
2422 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2423 numerator and denominator of the aspect ratio.
2424 If the parameter is not specified, it is assumed the value "0:1".
2426 For example to change the sample aspect ratio to 10:11, specify:
2433 Set the timebase to use for the output frames timestamps.
2434 It is mainly useful for testing timebase configuration.
2436 It accepts in input an arithmetic expression representing a rational.
2437 The expression can contain the constants "AVTB" (the
2438 default timebase), and "intb" (the input timebase).
2440 The default value for the input is "intb".
2442 Follow some examples.
2445 # set the timebase to 1/25
2448 # set the timebase to 1/10
2451 #set the timebase to 1001/1000
2454 #set the timebase to 2*intb
2457 #set the default timebase value
2463 Show a line containing various information for each input video frame.
2464 The input video is not modified.
2466 The shown line contains a sequence of key/value pairs of the form
2467 @var{key}:@var{value}.
2469 A description of each shown parameter follows:
2473 sequential number of the input frame, starting from 0
2476 Presentation TimeStamp of the input frame, expressed as a number of
2477 time base units. The time base unit depends on the filter input pad.
2480 Presentation TimeStamp of the input frame, expressed as a number of
2484 position of the frame in the input stream, -1 if this information in
2485 unavailable and/or meaningless (for example in case of synthetic video)
2491 sample aspect ratio of the input frame, expressed in the form
2495 size of the input frame, expressed in the form
2496 @var{width}x@var{height}
2499 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2500 for bottom field first)
2503 1 if the frame is a key frame, 0 otherwise
2506 picture type of the input frame ("I" for an I-frame, "P" for a
2507 P-frame, "B" for a B-frame, "?" for unknown type).
2508 Check also the documentation of the @code{AVPictureType} enum and of
2509 the @code{av_get_picture_type_char} function defined in
2510 @file{libavutil/avutil.h}.
2513 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2515 @item plane_checksum
2516 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2517 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2522 Pass the images of input video on to next video filter as multiple
2526 ffmpeg -i in.avi -vf "slicify=32" out.avi
2529 The filter accepts the slice height as parameter. If the parameter is
2530 not specified it will use the default value of 16.
2532 Adding this in the beginning of filter chains should make filtering
2533 faster due to better use of the memory cache.
2537 Pass on the input video to two outputs. Both outputs are identical to
2542 [in] split [splitout1][splitout2];
2543 [splitout1] crop=100:100:0:0 [cropout];
2544 [splitout2] pad=200:200:100:100 [padout];
2547 will create two separate outputs from the same input, one cropped and
2551 Select the most representative frame in a given sequence of consecutive frames.
2553 It accepts as argument the frames batch size to analyze (default @var{N}=100);
2554 in a set of @var{N} frames, the filter will pick one of them, and then handle
2555 the next batch of @var{N} frames until the end.
2557 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
2558 value will result in a higher memory usage, so a high value is not recommended.
2560 The following example extract one picture each 50 frames:
2565 Complete example of a thumbnail creation with @command{ffmpeg}:
2567 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
2572 Perform various types of temporal field interlacing.
2574 Frames are counted starting from 1, so the first input frame is
2577 This filter accepts a single parameter specifying the mode. Available
2582 Move odd frames into the upper field, even into the lower field,
2583 generating a double height frame at half framerate.
2586 Only output even frames, odd frames are dropped, generating a frame with
2587 unchanged height at half framerate.
2590 Only output odd frames, even frames are dropped, generating a frame with
2591 unchanged height at half framerate.
2594 Expand each frame to full height, but pad alternate lines with black,
2595 generating a frame with double height at the same input framerate.
2598 Interleave the upper field from odd frames with the lower field from
2599 even frames, generating a frame with unchanged height at half framerate.
2602 Interleave the lower field from odd frames with the upper field from
2603 even frames, generating a frame with unchanged height at half framerate.
2610 Transpose rows with columns in the input video and optionally flip it.
2612 It accepts a parameter representing an integer, which can assume the
2617 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2625 Rotate by 90 degrees clockwise, that is:
2633 Rotate by 90 degrees counterclockwise, that is:
2641 Rotate by 90 degrees clockwise and vertically flip, that is:
2651 Sharpen or blur the input video.
2653 It accepts the following parameters:
2654 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2656 Negative values for the amount will blur the input video, while positive
2657 values will sharpen. All parameters are optional and default to the
2658 equivalent of the string '5:5:1.0:5:5:0.0'.
2663 Set the luma matrix horizontal size. It can be an integer between 3
2664 and 13, default value is 5.
2667 Set the luma matrix vertical size. It can be an integer between 3
2668 and 13, default value is 5.
2671 Set the luma effect strength. It can be a float number between -2.0
2672 and 5.0, default value is 1.0.
2674 @item chroma_msize_x
2675 Set the chroma matrix horizontal size. It can be an integer between 3
2676 and 13, default value is 5.
2678 @item chroma_msize_y
2679 Set the chroma matrix vertical size. It can be an integer between 3
2680 and 13, default value is 5.
2683 Set the chroma effect strength. It can be a float number between -2.0
2684 and 5.0, default value is 0.0.
2689 # Strong luma sharpen effect parameters
2692 # Strong blur of both luma and chroma parameters
2693 unsharp=7:7:-2:7:7:-2
2695 # Use the default values with @command{ffmpeg}
2696 ffmpeg -i in.avi -vf "unsharp" out.mp4
2701 Flip the input video vertically.
2704 ffmpeg -i in.avi -vf "vflip" out.avi
2709 Deinterlace the input video ("yadif" means "yet another deinterlacing
2712 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2714 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2719 output 1 frame for each frame
2721 output 1 frame for each field
2723 like 0 but skips spatial interlacing check
2725 like 1 but skips spatial interlacing check
2730 @var{parity} specifies the picture field parity assumed for the input
2731 interlaced video, accepts one of the following values:
2735 assume top field first
2737 assume bottom field first
2739 enable automatic detection
2742 Default value is -1.
2743 If interlacing is unknown or decoder does not export this information,
2744 top field first will be assumed.
2746 @var{auto} specifies if deinterlacer should trust the interlaced flag
2747 and only deinterlace frames marked as interlaced
2751 deinterlace all frames
2753 only deinterlace frames marked as interlaced
2758 @c man end VIDEO FILTERS
2760 @chapter Video Sources
2761 @c man begin VIDEO SOURCES
2763 Below is a description of the currently available video sources.
2767 Buffer video frames, and make them available to the filter chain.
2769 This source is mainly intended for a programmatic use, in particular
2770 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2772 It accepts the following parameters:
2773 @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}
2775 All the parameters but @var{scale_params} need to be explicitly
2778 Follows the list of the accepted parameters.
2783 Specify the width and height of the buffered video frames.
2785 @item pix_fmt_string
2786 A string representing the pixel format of the buffered video frames.
2787 It may be a number corresponding to a pixel format, or a pixel format
2790 @item timebase_num, timebase_den
2791 Specify numerator and denomitor of the timebase assumed by the
2792 timestamps of the buffered frames.
2794 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2795 Specify numerator and denominator of the sample aspect ratio assumed
2796 by the video frames.
2799 Specify the optional parameters to be used for the scale filter which
2800 is automatically inserted when an input change is detected in the
2801 input size or format.
2806 buffer=320:240:yuv410p:1:24:1:1
2809 will instruct the source to accept video frames with size 320x240 and
2810 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2811 square pixels (1:1 sample aspect ratio).
2812 Since the pixel format with name "yuv410p" corresponds to the number 6
2813 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2814 this example corresponds to:
2816 buffer=320:240:6:1:24:1:1
2821 Create a pattern generated by an elementary cellular automaton.
2823 The initial state of the cellular automaton can be defined through the
2824 @option{filename}, and @option{pattern} options. If such options are
2825 not specified an initial state is created randomly.
2827 At each new frame a new row in the video is filled with the result of
2828 the cellular automaton next generation. The behavior when the whole
2829 frame is filled is defined by the @option{scroll} option.
2831 This source accepts a list of options in the form of
2832 @var{key}=@var{value} pairs separated by ":". A description of the
2833 accepted options follows.
2837 Read the initial cellular automaton state, i.e. the starting row, from
2839 In the file, each non-whitespace character is considered an alive
2840 cell, a newline will terminate the row, and further characters in the
2841 file will be ignored.
2844 Read the initial cellular automaton state, i.e. the starting row, from
2845 the specified string.
2847 Each non-whitespace character in the string is considered an alive
2848 cell, a newline will terminate the row, and further characters in the
2849 string will be ignored.
2852 Set the video rate, that is the number of frames generated per second.
2855 @item random_fill_ratio, ratio
2856 Set the random fill ratio for the initial cellular automaton row. It
2857 is a floating point number value ranging from 0 to 1, defaults to
2860 This option is ignored when a file or a pattern is specified.
2862 @item random_seed, seed
2863 Set the seed for filling randomly the initial row, must be an integer
2864 included between 0 and UINT32_MAX. If not specified, or if explicitly
2865 set to -1, the filter will try to use a good random seed on a best
2869 Set the cellular automaton rule, it is a number ranging from 0 to 255.
2870 Default value is 110.
2873 Set the size of the output video.
2875 If @option{filename} or @option{pattern} is specified, the size is set
2876 by default to the width of the specified initial state row, and the
2877 height is set to @var{width} * PHI.
2879 If @option{size} is set, it must contain the width of the specified
2880 pattern string, and the specified pattern will be centered in the
2883 If a filename or a pattern string is not specified, the size value
2884 defaults to "320x518" (used for a randomly generated initial state).
2887 If set to 1, scroll the output upward when all the rows in the output
2888 have been already filled. If set to 0, the new generated row will be
2889 written over the top row just after the bottom row is filled.
2892 @item start_full, full
2893 If set to 1, completely fill the output with generated rows before
2894 outputting the first frame.
2895 This is the default behavior, for disabling set the value to 0.
2898 If set to 1, stitch the left and right row edges together.
2899 This is the default behavior, for disabling set the value to 0.
2902 @subsection Examples
2906 Read the initial state from @file{pattern}, and specify an output of
2909 cellauto=f=pattern:s=200x400
2913 Generate a random initial row with a width of 200 cells, with a fill
2916 cellauto=ratio=2/3:s=200x200
2920 Create a pattern generated by rule 18 starting by a single alive cell
2921 centered on an initial row with width 100:
2923 cellauto=p=@@:s=100x400:full=0:rule=18
2927 Specify a more elaborated initial pattern:
2929 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
2936 Provide an uniformly colored input.
2938 It accepts the following parameters:
2939 @var{color}:@var{frame_size}:@var{frame_rate}
2941 Follows the description of the accepted parameters.
2946 Specify the color of the source. It can be the name of a color (case
2947 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2948 alpha specifier. The default value is "black".
2951 Specify the size of the sourced video, it may be a string of the form
2952 @var{width}x@var{height}, or the name of a size abbreviation. The
2953 default value is "320x240".
2956 Specify the frame rate of the sourced video, as the number of frames
2957 generated per second. It has to be a string in the format
2958 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2959 number or a valid video frame rate abbreviation. The default value is
2964 For example the following graph description will generate a red source
2965 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2966 frames per second, which will be overlayed over the source connected
2967 to the pad with identifier "in".
2970 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2975 Read a video stream from a movie container.
2977 It accepts the syntax: @var{movie_name}[:@var{options}] where
2978 @var{movie_name} is the name of the resource to read (not necessarily
2979 a file but also a device or a stream accessed through some protocol),
2980 and @var{options} is an optional sequence of @var{key}=@var{value}
2981 pairs, separated by ":".
2983 The description of the accepted options follows.
2987 @item format_name, f
2988 Specifies the format assumed for the movie to read, and can be either
2989 the name of a container or an input device. If not specified the
2990 format is guessed from @var{movie_name} or by probing.
2992 @item seek_point, sp
2993 Specifies the seek point in seconds, the frames will be output
2994 starting from this seek point, the parameter is evaluated with
2995 @code{av_strtod} so the numerical value may be suffixed by an IS
2996 postfix. Default value is "0".
2998 @item stream_index, si
2999 Specifies the index of the video stream to read. If the value is -1,
3000 the best suited video stream will be automatically selected. Default
3005 This filter allows to overlay a second video on top of main input of
3006 a filtergraph as shown in this graph:
3008 input -----------> deltapts0 --> overlay --> output
3011 movie --> scale--> deltapts1 -------+
3014 Some examples follow:
3016 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
3017 # on top of the input labelled as "in".
3018 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3019 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3021 # read from a video4linux2 device, and overlay it on top of the input
3023 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3024 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3030 Generate various test patterns, as generated by the MPlayer test filter.
3032 The size of the generated video is fixed, and is 256x256.
3033 This source is useful in particular for testing encoding features.
3035 This source accepts an optional sequence of @var{key}=@var{value} pairs,
3036 separated by ":". The description of the accepted options follows.
3041 Specify the frame rate of the sourced video, as the number of frames
3042 generated per second. It has to be a string in the format
3043 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3044 number or a valid video frame rate abbreviation. The default value is
3048 Set the video duration of the sourced video. The accepted syntax is:
3050 [-]HH[:MM[:SS[.m...]]]
3053 See also the function @code{av_parse_time()}.
3055 If not specified, or the expressed duration is negative, the video is
3056 supposed to be generated forever.
3060 Set the number or the name of the test to perform. Supported tests are:
3075 Default value is "all", which will cycle through the list of all tests.
3078 For example the following:
3083 will generate a "dc_luma" test pattern.
3087 Provide a frei0r source.
3089 To enable compilation of this filter you need to install the frei0r
3090 header and configure FFmpeg with @code{--enable-frei0r}.
3092 The source supports the syntax:
3094 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
3097 @var{size} is the size of the video to generate, may be a string of the
3098 form @var{width}x@var{height} or a frame size abbreviation.
3099 @var{rate} is the rate of the video to generate, may be a string of
3100 the form @var{num}/@var{den} or a frame rate abbreviation.
3101 @var{src_name} is the name to the frei0r source to load. For more
3102 information regarding frei0r and how to set the parameters read the
3103 section @ref{frei0r} in the description of the video filters.
3105 Some examples follow:
3107 # generate a frei0r partik0l source with size 200x200 and frame rate 10
3108 # which is overlayed on the overlay filter main input
3109 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
3114 Generate a life pattern.
3116 This source is based on a generalization of John Conway's life game.
3118 The sourced input represents a life grid, each pixel represents a cell
3119 which can be in one of two possible states, alive or dead. Every cell
3120 interacts with its eight neighbours, which are the cells that are
3121 horizontally, vertically, or diagonally adjacent.
3123 At each interaction the grid evolves according to the adopted rule,
3124 which specifies the number of neighbor alive cells which will make a
3125 cell stay alive or born. The @option{rule} option allows to specify
3128 This source accepts a list of options in the form of
3129 @var{key}=@var{value} pairs separated by ":". A description of the
3130 accepted options follows.
3134 Set the file from which to read the initial grid state. In the file,
3135 each non-whitespace character is considered an alive cell, and newline
3136 is used to delimit the end of each row.
3138 If this option is not specified, the initial grid is generated
3142 Set the video rate, that is the number of frames generated per second.
3145 @item random_fill_ratio, ratio
3146 Set the random fill ratio for the initial random grid. It is a
3147 floating point number value ranging from 0 to 1, defaults to 1/PHI.
3148 It is ignored when a file is specified.
3150 @item random_seed, seed
3151 Set the seed for filling the initial random grid, must be an integer
3152 included between 0 and UINT32_MAX. If not specified, or if explicitly
3153 set to -1, the filter will try to use a good random seed on a best
3159 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
3160 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
3161 @var{NS} specifies the number of alive neighbor cells which make a
3162 live cell stay alive, and @var{NB} the number of alive neighbor cells
3163 which make a dead cell to become alive (i.e. to "born").
3164 "s" and "b" can be used in place of "S" and "B", respectively.
3166 Alternatively a rule can be specified by an 18-bits integer. The 9
3167 high order bits are used to encode the next cell state if it is alive
3168 for each number of neighbor alive cells, the low order bits specify
3169 the rule for "borning" new cells. Higher order bits encode for an
3170 higher number of neighbor cells.
3171 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
3172 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
3174 Default value is "S23/B3", which is the original Conway's game of life
3175 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
3176 cells, and will born a new cell if there are three alive cells around
3180 Set the size of the output video.
3182 If @option{filename} is specified, the size is set by default to the
3183 same size of the input file. If @option{size} is set, it must contain
3184 the size specified in the input file, and the initial grid defined in
3185 that file is centered in the larger resulting area.
3187 If a filename is not specified, the size value defaults to "320x240"
3188 (used for a randomly generated initial grid).
3191 If set to 1, stitch the left and right grid edges together, and the
3192 top and bottom edges also. Defaults to 1.
3195 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
3196 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
3197 value from 0 to 255.
3200 Set the color of living (or new born) cells.
3203 Set the color of dead cells. If @option{mold} is set, this is the first color
3204 used to represent a dead cell.
3207 Set mold color, for definitely dead and moldy cells.
3210 @subsection Examples
3214 Read a grid from @file{pattern}, and center it on a grid of size
3217 life=f=pattern:s=300x300
3221 Generate a random grid of size 200x200, with a fill ratio of 2/3:
3223 life=ratio=2/3:s=200x200
3227 Specify a custom rule for evolving a randomly generated grid:
3233 Full example with slow death effect (mold) using @command{ffplay}:
3235 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
3239 @section nullsrc, rgbtestsrc, testsrc
3241 The @code{nullsrc} source returns unprocessed video frames. It is
3242 mainly useful to be employed in analysis / debugging tools, or as the
3243 source for filters which ignore the input data.
3245 The @code{rgbtestsrc} source generates an RGB test pattern useful for
3246 detecting RGB vs BGR issues. You should see a red, green and blue
3247 stripe from top to bottom.
3249 The @code{testsrc} source generates a test video pattern, showing a
3250 color pattern, a scrolling gradient and a timestamp. This is mainly
3251 intended for testing purposes.
3253 These sources accept an optional sequence of @var{key}=@var{value} pairs,
3254 separated by ":". The description of the accepted options follows.
3259 Specify the size of the sourced video, it may be a string of the form
3260 @var{width}x@var{height}, or the name of a size abbreviation. The
3261 default value is "320x240".
3264 Specify the frame rate of the sourced video, as the number of frames
3265 generated per second. It has to be a string in the format
3266 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3267 number or a valid video frame rate abbreviation. The default value is
3271 Set the sample aspect ratio of the sourced video.
3274 Set the video duration of the sourced video. The accepted syntax is:
3276 [-]HH[:MM[:SS[.m...]]]
3279 See also the function @code{av_parse_time()}.
3281 If not specified, or the expressed duration is negative, the video is
3282 supposed to be generated forever.
3285 Set the number of decimals to show in the timestamp, only used in the
3286 @code{testsrc} source.
3288 The displayed timestamp value will correspond to the original
3289 timestamp value multiplied by the power of 10 of the specified
3290 value. Default value is 0.
3293 For example the following:
3295 testsrc=duration=5.3:size=qcif:rate=10
3298 will generate a video with a duration of 5.3 seconds, with size
3299 176x144 and a frame rate of 10 frames per second.
3301 If the input content is to be ignored, @code{nullsrc} can be used. The
3302 following command generates noise in the luminance plane by employing
3303 the @code{mp=geq} filter:
3305 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
3308 @c man end VIDEO SOURCES
3310 @chapter Video Sinks
3311 @c man begin VIDEO SINKS
3313 Below is a description of the currently available video sinks.
3317 Buffer video frames, and make them available to the end of the filter
3320 This sink is mainly intended for a programmatic use, in particular
3321 through the interface defined in @file{libavfilter/buffersink.h}.
3323 It does not require a string parameter in input, but you need to
3324 specify a pointer to a list of supported pixel formats terminated by
3325 -1 in the opaque parameter provided to @code{avfilter_init_filter}
3326 when initializing this sink.
3330 Null video sink, do absolutely nothing with the input video. It is
3331 mainly useful as a template and to be employed in analysis / debugging
3334 @c man end VIDEO SINKS