1 @chapter Filtergraph description
2 @c man begin FILTERGRAPH DESCRIPTION
4 A filtergraph is a directed graph of connected filters. It can contain
5 cycles, and there can be multiple links between a pair of
6 filters. Each link has one input pad on one side connecting it to one
7 filter from which it takes its input, and one output pad on the other
8 side connecting it to the one filter accepting its output.
10 Each filter in a filtergraph is an instance of a filter class
11 registered in the application, which defines the features and the
12 number of input and output pads of the filter.
14 A filter with no input pads is called a "source", a filter with no
15 output pads is called a "sink".
17 @section Filtergraph syntax
19 A filtergraph can be represented using a textual representation, which
20 is recognized by the @code{-vf} option of the ff*
21 tools, and by the @code{avfilter_graph_parse()} function defined in
22 @file{libavfilter/avfiltergraph.h}.
24 A filterchain consists of a sequence of connected filters, each one
25 connected to the previous one in the sequence. A filterchain is
26 represented by a list of ","-separated filter descriptions.
28 A filtergraph consists of a sequence of filterchains. A sequence of
29 filterchains is represented by a list of ";"-separated filterchain
32 A filter is represented by a string of the form:
33 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
35 @var{filter_name} is the name of the filter class of which the
36 described filter is an instance of, and has to be the name of one of
37 the filter classes registered in the program.
38 The name of the filter class is optionally followed by a string
41 @var{arguments} is a string which contains the parameters used to
42 initialize the filter instance, and are described in the filter
45 The list of arguments can be quoted using the character "'" as initial
46 and ending mark, and the character '\' for escaping the characters
47 within the quoted text; otherwise the argument string is considered
48 terminated when the next special character (belonging to the set
49 "[]=;,") is encountered.
51 The name and arguments of the filter are optionally preceded and
52 followed by a list of link labels.
53 A link label allows to name a link and associate it to a filter output
54 or input pad. The preceding labels @var{in_link_1}
55 ... @var{in_link_N}, are associated to the filter input pads,
56 the following labels @var{out_link_1} ... @var{out_link_M}, are
57 associated to the output pads.
59 When two link labels with the same name are found in the
60 filtergraph, a link between the corresponding input and output pad is
63 If an output pad is not labelled, it is linked by default to the first
64 unlabelled input pad of the next filter in the filterchain.
65 For example in the filterchain:
67 nullsrc, split[L1], [L2]overlay, nullsink
69 the split filter instance has two output pads, and the overlay filter
70 instance two input pads. The first output pad of split is labelled
71 "L1", the first input pad of overlay is labelled "L2", and the second
72 output pad of split is linked to the second input pad of overlay,
73 which are both unlabelled.
75 In a complete filterchain all the unlabelled filter input and output
76 pads must be connected. A filtergraph is considered valid if all the
77 filter input and output pads of all the filterchains are connected.
79 Follows a BNF description for the filtergraph syntax:
81 @var{NAME} ::= sequence of alphanumeric characters and '_'
82 @var{LINKLABEL} ::= "[" @var{NAME} "]"
83 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
84 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
85 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
86 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
87 @var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
90 @c man end FILTERGRAPH DESCRIPTION
92 @chapter Audio Filters
93 @c man begin AUDIO FILTERS
95 When you configure your FFmpeg build, you can disable any of the
96 existing filters using @code{--disable-filters}.
97 The configure output will show the audio filters included in your
100 Below is a description of the currently available audio filters.
104 Convert the input audio format to the specified formats.
106 The filter accepts a string of the form:
107 "@var{sample_format}:@var{channel_layout}".
109 @var{sample_format} specifies the sample format, and can be a string or the
110 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
111 suffix for a planar sample format.
113 @var{channel_layout} specifies the channel layout, and can be a string
114 or the corresponding number value defined in @file{libavutil/audioconvert.h}.
116 The special parameter "auto", signifies that the filter will
117 automatically select the output format depending on the output filter.
119 Some examples follow.
123 Convert input to float, planar, stereo:
129 Convert input to unsigned 8-bit, automatically select out channel layout:
137 Convert the input audio to one of the specified formats. The framework will
138 negotiate the most appropriate format to minimize conversions.
140 The filter accepts three lists of formats, separated by ":", in the form:
141 "@var{sample_formats}:@var{channel_layouts}:@var{packing_formats}".
143 Elements in each list are separated by "," which has to be escaped in the
144 filtergraph specification.
146 The special parameter "all", in place of a list of elements, signifies all
149 Some examples follow:
151 aformat=u8\\,s16:mono:packed
153 aformat=s16:mono\\,stereo:all
158 Merge two audio streams into a single multi-channel stream.
160 This filter does not need any argument.
162 If the channel layouts of the inputs are disjoint, and therefore compatible,
163 the channel layout of the output will be set accordingly and the channels
164 will be reordered as necessary. If the channel layouts of the inputs are not
165 disjoint, the output will have all the channels of the first input then all
166 the channels of the second input, in that order, and the channel layout of
167 the output will be the default value corresponding to the total number of
170 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
171 is FC+BL+BR, then the output will be in 5.1, with the channels in the
172 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
173 first input, b1 is the first channel of the second input).
175 On the other hand, if both input are in stereo, the output channels will be
176 in the default order: a1, a2, b1, b2, and the channel layout will be
177 arbitrarily set to 4.0, which may or may not be the expected value.
179 Both inputs must have the same sample rate, format and packing.
181 If inputs do not have the same duration, the output will stop with the
184 Example: merge two mono files into a stereo stream:
186 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
189 If you need to do multiple merges (for instance multiple mono audio streams in
190 a single video media), you can do:
193 amovie=input.mkv:si=0 [a0];
194 amovie=input.mkv:si=1 [a1];
195 amovie=input.mkv:si=2 [a2];
196 amovie=input.mkv:si=3 [a3];
197 amovie=input.mkv:si=4 [a4];
198 amovie=input.mkv:si=5 [a5];
199 [a0][a1] amerge [x0];
200 [x0][a2] amerge [x1];
201 [x1][a3] amerge [x2];
202 [x2][a4] amerge [x3];
203 [x3][a5] amerge" -c:a pcm_s16le output.mkv
208 Pass the audio source unchanged to the output.
212 Resample the input audio to the specified sample rate.
214 The filter accepts exactly one parameter, the output sample rate. If not
215 specified then the filter will automatically convert between its input
216 and output sample rates.
218 For example, to resample the input audio to 44100Hz:
225 Show a line containing various information for each input audio frame.
226 The input audio is not modified.
228 The shown line contains a sequence of key/value pairs of the form
229 @var{key}:@var{value}.
231 A description of each shown parameter follows:
235 sequential number of the input frame, starting from 0
238 presentation TimeStamp of the input frame, expressed as a number of
239 time base units. The time base unit depends on the filter input pad, and
240 is usually 1/@var{sample_rate}.
243 presentation TimeStamp of the input frame, expressed as a number of
247 position of the frame in the input stream, -1 if this information in
248 unavailable and/or meaningless (for example in case of synthetic audio)
254 channel layout description
257 number of samples (per each channel) contained in the filtered frame
260 sample rate for the audio frame
263 if the packing format is planar, 0 if packed
266 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
269 Adler-32 checksum (printed in hexadecimal) for each input frame plane,
270 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
276 Pass on the input audio to two outputs. Both outputs are identical to
281 [in] asplit[out0], showaudio[out1]
284 will create two separate outputs from the same input, one cropped and
289 Forward two audio streams and control the order the buffers are forwarded.
291 The argument to the filter is an expression deciding which stream should be
292 forwarded next: if the result is negative, the first stream is forwarded; if
293 the result is positive or zero, the second stream is forwarded. It can use
294 the following variables:
298 number of buffers forwarded so far on each stream
300 number of samples forwarded so far on each stream
302 current timestamp of each stream
305 The default value is @code{t1-t2}, which means to always forward the stream
306 that has a smaller timestamp.
308 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
309 input, while avoiding too much of a desynchronization:
311 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
312 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
318 Make audio easier to listen to on headphones.
320 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
321 so that when listened to on headphones the stereo image is moved from
322 inside your head (standard for headphones) to outside and in front of
323 the listener (standard for speakers).
329 Mix channels with specific gain levels. The filter accepts the output
330 channel layout followed by a set of channels definitions.
332 This filter is also designed to remap efficiently the channels of an audio
335 The filter accepts parameters of the form:
336 "@var{l}:@var{outdef}:@var{outdef}:..."
340 output channel layout or number of channels
343 output channel specification, of the form:
344 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
347 output channel to define, either a channel name (FL, FR, etc.) or a channel
348 number (c0, c1, etc.)
351 multiplicative coefficient for the channel, 1 leaving the volume unchanged
354 input channel to use, see out_name for details; it is not possible to mix
355 named and numbered input channels
358 If the `=' in a channel specification is replaced by `<', then the gains for
359 that specification will be renormalized so that the total is 1, thus
360 avoiding clipping noise.
362 @subsection Mixing examples
364 For example, if you want to down-mix from stereo to mono, but with a bigger
365 factor for the left channel:
367 pan=1:c0=0.9*c0+0.1*c1
370 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
373 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
376 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
377 that should be preferred (see "-ac" option) unless you have very specific
380 @subsection Remapping examples
382 The channel remapping will be effective if, and only if:
385 @item gain coefficients are zeroes or ones,
386 @item only one input per channel output,
389 If all these conditions are satisfied, the filter will notify the user ("Pure
390 channel mapping detected"), and use an optimized and lossless method to do the
393 For example, if you have a 5.1 source and want a stereo audio stream by
394 dropping the extra channels:
396 pan="stereo: c0=FL : c1=FR"
399 Given the same source, you can also switch front left and front right channels
400 and keep the input channel layout:
402 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
405 If the input is a stereo audio stream, you can mute the front left channel (and
406 still keep the stereo channel layout) with:
411 Still with a stereo audio stream input, you can copy the right channel in both
412 front left and right:
414 pan="stereo: c0=FR : c1=FR"
417 @section silencedetect
419 Detect silence in an audio stream.
421 This filter logs a message when it detects that the input audio volume is less
422 or equal to a noise tolerance value for a duration greater or equal to the
423 minimum detected noise duration.
425 The printed times and duration are expressed in seconds.
429 Set silence duration until notification (default is 2 seconds).
432 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
433 specified value) or amplitude ratio. Default is -60dB, or 0.001.
436 Detect 5 seconds of silence with -50dB noise tolerance:
438 silencedetect=n=-50dB:d=5
441 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
442 tolerance in @file{silence.mp3}:
444 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
449 Adjust the input audio volume.
451 The filter accepts exactly one parameter @var{vol}, which expresses
452 how the audio volume will be increased or decreased.
454 Output values are clipped to the maximum value.
456 If @var{vol} is expressed as a decimal number, the output audio
457 volume is given by the relation:
459 @var{output_volume} = @var{vol} * @var{input_volume}
462 If @var{vol} is expressed as a decimal number followed by the string
463 "dB", the value represents the requested change in decibels of the
464 input audio power, and the output audio volume is given by the
467 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
470 Otherwise @var{vol} is considered an expression and its evaluated
471 value is used for computing the output audio volume according to the
474 Default value for @var{vol} is 1.0.
480 Half the input audio volume:
485 The above example is equivalent to:
491 Decrease input audio power by 12 decibels:
497 @c man end AUDIO FILTERS
499 @chapter Audio Sources
500 @c man begin AUDIO SOURCES
502 Below is a description of the currently available audio sources.
506 Buffer audio frames, and make them available to the filter chain.
508 This source is mainly intended for a programmatic use, in particular
509 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
511 It accepts the following mandatory parameters:
512 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
517 The sample rate of the incoming audio buffers.
520 The sample format of the incoming audio buffers.
521 Either a sample format name or its corresponging integer representation from
522 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
525 The channel layout of the incoming audio buffers.
526 Either a channel layout name from channel_layout_map in
527 @file{libavutil/audioconvert.c} or its corresponding integer representation
528 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
531 Either "packed" or "planar", or their integer representation: 0 or 1
538 abuffer=44100:s16:stereo:planar
541 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
542 Since the sample format with name "s16" corresponds to the number
543 1 and the "stereo" channel layout corresponds to the value 0x3, this is
546 abuffer=44100:1:0x3:1
551 Generate an audio signal specified by an expression.
553 This source accepts in input one or more expressions (one for each
554 channel), which are evaluated and used to generate a corresponding
557 It accepts the syntax: @var{exprs}[::@var{options}].
558 @var{exprs} is a list of expressions separated by ":", one for each
559 separate channel. The output channel layout depends on the number of
560 provided expressions, up to 8 channels are supported.
562 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
565 The description of the accepted options follows.
570 Set the minimum duration of the sourced audio. See the function
571 @code{av_parse_time()} for the accepted format.
572 Note that the resulting duration may be greater than the specified
573 duration, as the generated audio is always cut at the end of a
576 If not specified, or the expressed duration is negative, the audio is
577 supposed to be generated forever.
580 Set the number of samples per channel per each output frame,
584 Specify the sample rate, default to 44100.
587 Each expression in @var{exprs} can contain the following constants:
591 number of the evaluated sample, starting from 0
594 time of the evaluated sample expressed in seconds, starting from 0
613 Generate a sin signal with frequency of 440 Hz, set sample rate to
616 aevalsrc="sin(440*2*PI*t)::s=8000"
620 Generate white noise:
622 aevalsrc="-2+random(0)"
626 Generate an amplitude modulated signal:
628 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
632 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
634 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
641 Read an audio stream from a movie container.
643 It accepts the syntax: @var{movie_name}[:@var{options}] where
644 @var{movie_name} is the name of the resource to read (not necessarily
645 a file but also a device or a stream accessed through some protocol),
646 and @var{options} is an optional sequence of @var{key}=@var{value}
647 pairs, separated by ":".
649 The description of the accepted options follows.
654 Specify the format assumed for the movie to read, and can be either
655 the name of a container or an input device. If not specified the
656 format is guessed from @var{movie_name} or by probing.
659 Specify the seek point in seconds, the frames will be output
660 starting from this seek point, the parameter is evaluated with
661 @code{av_strtod} so the numerical value may be suffixed by an IS
662 postfix. Default value is "0".
664 @item stream_index, si
665 Specify the index of the audio stream to read. If the value is -1,
666 the best suited audio stream will be automatically selected. Default
673 Null audio source, return unprocessed audio frames. It is mainly useful
674 as a template and to be employed in analysis / debugging tools, or as
675 the source for filters which ignore the input data (for example the sox
678 It accepts an optional sequence of @var{key}=@var{value} pairs,
681 The description of the accepted options follows.
686 Specify the sample rate, and defaults to 44100.
688 @item channel_layout, cl
690 Specify the channel layout, and can be either an integer or a string
691 representing a channel layout. The default value of @var{channel_layout}
694 Check the channel_layout_map definition in
695 @file{libavcodec/audioconvert.c} for the mapping between strings and
696 channel layout values.
699 Set the number of samples per requested frames.
703 Follow some examples:
705 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
706 anullsrc=r=48000:cl=4
709 anullsrc=r=48000:cl=mono
712 @c man end AUDIO SOURCES
715 @c man begin AUDIO SINKS
717 Below is a description of the currently available audio sinks.
721 Buffer audio frames, and make them available to the end of filter chain.
723 This sink is mainly intended for programmatic use, in particular
724 through the interface defined in @file{libavfilter/buffersink.h}.
726 It requires a pointer to an AVABufferSinkContext structure, which
727 defines the incoming buffers' formats, to be passed as the opaque
728 parameter to @code{avfilter_init_filter} for initialization.
732 Null audio sink, do absolutely nothing with the input audio. It is
733 mainly useful as a template and to be employed in analysis / debugging
736 @c man end AUDIO SINKS
738 @chapter Video Filters
739 @c man begin VIDEO FILTERS
741 When you configure your FFmpeg build, you can disable any of the
742 existing filters using @code{--disable-filters}.
743 The configure output will show the video filters included in your
746 Below is a description of the currently available video filters.
750 Draw ASS (Advanced Substation Alpha) subtitles on top of input video
751 using the libass library.
753 To enable compilation of this filter you need to configure FFmpeg with
754 @code{--enable-libass}.
756 This filter accepts the syntax: @var{ass_filename}[:@var{options}],
757 where @var{ass_filename} is the filename of the ASS file to read, and
758 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
761 A description of the accepted options follows.
765 Specifies the display aspect ratio adopted for rendering the
766 subtitles. Default value is "1.0".
769 For example, to render the file @file{sub.ass} on top of the input
770 video, use the command:
777 Compute the bounding box for the non-black pixels in the input frame
780 This filter computes the bounding box containing all the pixels with a
781 luminance value greater than the minimum allowed value.
782 The parameters describing the bounding box are printed on the filter
787 Detect video intervals that are (almost) completely black. Can be
788 useful to detect chapter transitions, commercials, or invalid
789 recordings. Output lines contains the time for the start, end and
790 duration of the detected black interval expressed in seconds.
792 In order to display the output lines, you need to set the loglevel at
793 least to the AV_LOG_INFO value.
795 This filter accepts a list of options in the form of
796 @var{key}=@var{value} pairs separated by ":". A description of the
797 accepted options follows.
800 @item black_min_duration, d
801 Set the minimum detected black duration expressed in seconds. It must
802 be a non-negative floating point number.
804 Default value is 2.0.
806 @item picture_black_ratio_th, pic_th
807 Set the threshold for considering a picture "black".
808 Express the minimum value for the ratio:
810 @var{nb_black_pixels} / @var{nb_pixels}
813 for which a picture is considered black.
814 Default value is 0.98.
816 @item pixel_black_th, pix_th
817 Set the threshold for considering a pixel "black".
819 The threshold expresses the maximum pixel luminance value for which a
820 pixel is considered "black". The provided value is scaled according to
821 the following equation:
823 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
826 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
827 the input video format, the range is [0-255] for YUV full-range
828 formats and [16-235] for YUV non full-range formats.
830 Default value is 0.10.
833 The following example sets the maximum pixel threshold to the minimum
834 value, and detects only black intervals of 2 or more seconds:
836 blackdetect=d=2:pix_th=0.00
841 Detect frames that are (almost) completely black. Can be useful to
842 detect chapter transitions or commercials. Output lines consist of
843 the frame number of the detected frame, the percentage of blackness,
844 the position in the file if known or -1 and the timestamp in seconds.
846 In order to display the output lines, you need to set the loglevel at
847 least to the AV_LOG_INFO value.
849 The filter accepts the syntax:
851 blackframe[=@var{amount}:[@var{threshold}]]
854 @var{amount} is the percentage of the pixels that have to be below the
855 threshold, and defaults to 98.
857 @var{threshold} is the threshold below which a pixel value is
858 considered black, and defaults to 32.
862 Apply boxblur algorithm to the input video.
864 This filter accepts the parameters:
865 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
867 Chroma and alpha parameters are optional, if not specified they default
868 to the corresponding values set for @var{luma_radius} and
871 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
872 the radius in pixels of the box used for blurring the corresponding
873 input plane. They are expressions, and can contain the following
877 the input width and height in pixels
880 the input chroma image width and height in pixels
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 radius must be a non-negative number, and must not be greater than
888 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
889 and of @code{min(cw,ch)/2} for the chroma planes.
891 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
892 how many times the boxblur filter is applied to the corresponding
895 Some examples follow:
900 Apply a boxblur filter with luma, chroma, and alpha radius
907 Set luma radius to 2, alpha and chroma radius to 0
913 Set luma and chroma radius to a fraction of the video dimension
915 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
922 Copy the input source unchanged to the output. Mainly useful for
927 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
929 The @var{keep_aspect} parameter is optional, if specified and set to a
930 non-zero value will force the output display aspect ratio to be the
931 same of the input, by changing the output sample aspect ratio.
933 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
934 expressions containing the following constants:
938 the computed values for @var{x} and @var{y}. They are evaluated for
942 the input width and height
945 same as @var{in_w} and @var{in_h}
948 the output (cropped) width and height
951 same as @var{out_w} and @var{out_h}
954 same as @var{iw} / @var{ih}
957 input sample aspect ratio
960 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
963 horizontal and vertical chroma subsample values. For example for the
964 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
967 the number of input frame, starting from 0
970 the position in the file of the input frame, NAN if unknown
973 timestamp expressed in seconds, NAN if the input timestamp is unknown
977 The @var{out_w} and @var{out_h} parameters specify the expressions for
978 the width and height of the output (cropped) video. They are
979 evaluated just at the configuration of the filter.
981 The default value of @var{out_w} is "in_w", and the default value of
982 @var{out_h} is "in_h".
984 The expression for @var{out_w} may depend on the value of @var{out_h},
985 and the expression for @var{out_h} may depend on @var{out_w}, but they
986 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
987 evaluated after @var{out_w} and @var{out_h}.
989 The @var{x} and @var{y} parameters specify the expressions for the
990 position of the top-left corner of the output (non-cropped) area. They
991 are evaluated for each frame. If the evaluated value is not valid, it
992 is approximated to the nearest valid value.
994 The default value of @var{x} is "(in_w-out_w)/2", and the default
995 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
996 the center of the input image.
998 The expression for @var{x} may depend on @var{y}, and the expression
999 for @var{y} may depend on @var{x}.
1001 Follow some examples:
1003 # crop the central input area with size 100x100
1006 # crop the central input area with size 2/3 of the input video
1007 "crop=2/3*in_w:2/3*in_h"
1009 # crop the input video central square
1012 # delimit the rectangle with the top-left corner placed at position
1013 # 100:100 and the right-bottom corner corresponding to the right-bottom
1014 # corner of the input image.
1015 crop=in_w-100:in_h-100:100:100
1017 # crop 10 pixels from the left and right borders, and 20 pixels from
1018 # the top and bottom borders
1019 "crop=in_w-2*10:in_h-2*20"
1021 # keep only the bottom right quarter of the input image
1022 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1024 # crop height for getting Greek harmony
1025 "crop=in_w:1/PHI*in_w"
1028 "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)"
1030 # erratic camera effect depending on timestamp
1031 "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)"
1033 # set x depending on the value of y
1034 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1039 Auto-detect crop size.
1041 Calculate necessary cropping parameters and prints the recommended
1042 parameters through the logging system. The detected dimensions
1043 correspond to the non-black area of the input video.
1045 It accepts the syntax:
1047 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1053 Threshold, which can be optionally specified from nothing (0) to
1054 everything (255), defaults to 24.
1057 Value which the width/height should be divisible by, defaults to
1058 16. The offset is automatically adjusted to center the video. Use 2 to
1059 get only even dimensions (needed for 4:2:2 video). 16 is best when
1060 encoding to most video codecs.
1063 Counter that determines after how many frames cropdetect will reset
1064 the previously detected largest video area and start over to detect
1065 the current optimal crop area. Defaults to 0.
1067 This can be useful when channel logos distort the video area. 0
1068 indicates never reset and return the largest area encountered during
1074 Suppress a TV station logo by a simple interpolation of the surrounding
1075 pixels. Just set a rectangle covering the logo and watch it disappear
1076 (and sometimes something even uglier appear - your mileage may vary).
1078 The filter accepts parameters as a string of the form
1079 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1080 @var{key}=@var{value} pairs, separated by ":".
1082 The description of the accepted parameters follows.
1087 Specify the top left corner coordinates of the logo. They must be
1091 Specify the width and height of the logo to clear. They must be
1095 Specify the thickness of the fuzzy edge of the rectangle (added to
1096 @var{w} and @var{h}). The default value is 4.
1099 When set to 1, a green rectangle is drawn on the screen to simplify
1100 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1101 @var{band} is set to 4. The default value is 0.
1105 Some examples follow.
1110 Set a rectangle covering the area with top left corner coordinates 0,0
1111 and size 100x77, setting a band of size 10:
1113 delogo=0:0:100:77:10
1117 As the previous example, but use named options:
1119 delogo=x=0:y=0:w=100:h=77:band=10
1126 Attempt to fix small changes in horizontal and/or vertical shift. This
1127 filter helps remove camera shake from hand-holding a camera, bumping a
1128 tripod, moving on a vehicle, etc.
1130 The filter accepts parameters as a string of the form
1131 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1133 A description of the accepted parameters follows.
1138 Specify a rectangular area where to limit the search for motion
1140 If desired the search for motion vectors can be limited to a
1141 rectangular area of the frame defined by its top left corner, width
1142 and height. These parameters have the same meaning as the drawbox
1143 filter which can be used to visualise the position of the bounding
1146 This is useful when simultaneous movement of subjects within the frame
1147 might be confused for camera motion by the motion vector search.
1149 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1150 then the full frame is used. This allows later options to be set
1151 without specifying the bounding box for the motion vector search.
1153 Default - search the whole frame.
1156 Specify the maximum extent of movement in x and y directions in the
1157 range 0-64 pixels. Default 16.
1160 Specify how to generate pixels to fill blanks at the edge of the
1161 frame. An integer from 0 to 3 as follows:
1164 Fill zeroes at blank locations
1166 Original image at blank locations
1168 Extruded edge value at blank locations
1170 Mirrored edge at blank locations
1173 The default setting is mirror edge at blank locations.
1176 Specify the blocksize to use for motion search. Range 4-128 pixels,
1180 Specify the contrast threshold for blocks. Only blocks with more than
1181 the specified contrast (difference between darkest and lightest
1182 pixels) will be considered. Range 1-255, default 125.
1185 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1186 search. Default - exhaustive search.
1189 If set then a detailed log of the motion search is written to the
1196 Draw a colored box on the input image.
1198 It accepts the syntax:
1200 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
1206 Specify the top left corner coordinates of the box. Default to 0.
1209 Specify the width and height of the box, if 0 they are interpreted as
1210 the input width and height. Default to 0.
1213 Specify the color of the box to write, it can be the name of a color
1214 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1217 Follow some examples:
1219 # draw a black box around the edge of the input image
1222 # draw a box with color red and an opacity of 50%
1223 drawbox=10:20:200:60:red@@0.5"
1228 Draw text string or text from specified file on top of video using the
1229 libfreetype library.
1231 To enable compilation of this filter you need to configure FFmpeg with
1232 @code{--enable-libfreetype}.
1234 The filter also recognizes strftime() sequences in the provided text
1235 and expands them accordingly. Check the documentation of strftime().
1237 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1240 The description of the accepted parameters follows.
1245 The font file to be used for drawing text. Path must be included.
1246 This parameter is mandatory.
1249 The text string to be drawn. The text must be a sequence of UTF-8
1251 This parameter is mandatory if no file is specified with the parameter
1255 A text file containing text to be drawn. The text must be a sequence
1256 of UTF-8 encoded characters.
1258 This parameter is mandatory if no text string is specified with the
1259 parameter @var{text}.
1261 If both text and textfile are specified, an error is thrown.
1264 The expressions which specify the offsets where text will be drawn
1265 within the video frame. They are relative to the top/left border of the
1268 The default value of @var{x} and @var{y} is "0".
1270 See below for the list of accepted constants.
1273 The font size to be used for drawing text.
1274 The default value of @var{fontsize} is 16.
1277 The color to be used for drawing fonts.
1278 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1279 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1280 The default value of @var{fontcolor} is "black".
1283 The color to be used for drawing box around text.
1284 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1285 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1286 The default value of @var{boxcolor} is "white".
1289 Used to draw a box around text using background color.
1290 Value should be either 1 (enable) or 0 (disable).
1291 The default value of @var{box} is 0.
1293 @item shadowx, shadowy
1294 The x and y offsets for the text shadow position with respect to the
1295 position of the text. They can be either positive or negative
1296 values. Default value for both is "0".
1299 The color to be used for drawing a shadow behind the drawn text. It
1300 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1301 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1302 The default value of @var{shadowcolor} is "black".
1305 Flags to be used for loading the fonts.
1307 The flags map the corresponding flags supported by libfreetype, and are
1308 a combination of the following values:
1315 @item vertical_layout
1316 @item force_autohint
1319 @item ignore_global_advance_width
1321 @item ignore_transform
1328 Default value is "render".
1330 For more information consult the documentation for the FT_LOAD_*
1334 The size in number of spaces to use for rendering the tab.
1338 If true, check and fix text coords to avoid clipping.
1341 The parameters for @var{x} and @var{y} are expressions containing the
1342 following constants:
1346 the input width and height
1349 the width of the rendered text
1352 the height of the rendered text
1355 the height of each text line
1358 input sample aspect ratio
1361 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1364 horizontal and vertical chroma subsample values. For example for the
1365 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1368 maximum glyph width, that is the maximum width for all the glyphs
1369 contained in the rendered text
1372 maximum glyph height, that is the maximum height for all the glyphs
1373 contained in the rendered text, it is equivalent to @var{ascent} -
1376 @item max_glyph_a, ascent
1378 the maximum distance from the baseline to the highest/upper grid
1379 coordinate used to place a glyph outline point, for all the rendered
1381 It is a positive value, due to the grid's orientation with the Y axis
1384 @item max_glyph_d, descent
1385 the maximum distance from the baseline to the lowest grid coordinate
1386 used to place a glyph outline point, for all the rendered glyphs.
1387 This is a negative value, due to the grid's orientation, with the Y axis
1391 the number of input frame, starting from 0
1394 timestamp expressed in seconds, NAN if the input timestamp is unknown
1397 initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
1398 with or without text parameter. @var{rate} option must be specified.
1401 frame rate (timecode only)
1404 Some examples follow.
1409 Draw "Test Text" with font FreeSerif, using the default values for the
1410 optional parameters.
1413 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1417 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1418 and y=50 (counting from the top-left corner of the screen), text is
1419 yellow with a red box around it. Both the text and the box have an
1423 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1424 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1427 Note that the double quotes are not necessary if spaces are not used
1428 within the parameter list.
1431 Show the text at the center of the video frame:
1433 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1437 Show a text line sliding from right to left in the last row of the video
1438 frame. The file @file{LONG_LINE} is assumed to contain a single line
1441 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1445 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1447 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1451 Draw a single green letter "g", at the center of the input video.
1452 The glyph baseline is placed at half screen height.
1454 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1459 For more information about libfreetype, check:
1460 @url{http://www.freetype.org/}.
1464 Apply fade-in/out effect to input video.
1466 It accepts the parameters:
1467 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1469 @var{type} specifies if the effect type, can be either "in" for
1470 fade-in, or "out" for a fade-out effect.
1472 @var{start_frame} specifies the number of the start frame for starting
1473 to apply the fade effect.
1475 @var{nb_frames} specifies the number of frames for which the fade
1476 effect has to last. At the end of the fade-in effect the output video
1477 will have the same intensity as the input video, at the end of the
1478 fade-out transition the output video will be completely black.
1480 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1481 separated by ":". The description of the accepted options follows.
1488 @item start_frame, s
1489 See @var{start_frame}.
1492 See @var{nb_frames}.
1495 If set to 1, fade only alpha channel, if one exists on the input.
1499 A few usage examples follow, usable too as test scenarios.
1501 # fade in first 30 frames of video
1504 # fade out last 45 frames of a 200-frame video
1507 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1508 fade=in:0:25, fade=out:975:25
1510 # make first 5 frames black, then fade in from frame 5-24
1513 # fade in alpha over first 25 frames of video
1514 fade=in:0:25:alpha=1
1519 Transform the field order of the input video.
1521 It accepts one parameter which specifies the required field order that
1522 the input interlaced video will be transformed to. The parameter can
1523 assume one of the following values:
1527 output bottom field first
1529 output top field first
1532 Default value is "tff".
1534 Transformation is achieved by shifting the picture content up or down
1535 by one line, and filling the remaining line with appropriate picture content.
1536 This method is consistent with most broadcast field order converters.
1538 If the input video is not flagged as being interlaced, or it is already
1539 flagged as being of the required output field order then this filter does
1540 not alter the incoming video.
1542 This filter is very useful when converting to or from PAL DV material,
1543 which is bottom field first.
1547 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1552 Buffer input images and send them when they are requested.
1554 This filter is mainly useful when auto-inserted by the libavfilter
1557 The filter does not take parameters.
1561 Convert the input video to one of the specified pixel formats.
1562 Libavfilter will try to pick one that is supported for the input to
1565 The filter accepts a list of pixel format names, separated by ":",
1566 for example "yuv420p:monow:rgb24".
1568 Some examples follow:
1570 # convert the input video to the format "yuv420p"
1573 # convert the input video to any of the formats in the list
1574 format=yuv420p:yuv444p:yuv410p
1580 Apply a frei0r effect to the input video.
1582 To enable compilation of this filter you need to install the frei0r
1583 header and configure FFmpeg with @code{--enable-frei0r}.
1585 The filter supports the syntax:
1587 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1590 @var{filter_name} is the name to the frei0r effect to load. If the
1591 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1592 is searched in each one of the directories specified by the colon
1593 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1594 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1595 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1597 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1598 for the frei0r effect.
1600 A frei0r effect parameter can be a boolean (whose values are specified
1601 with "y" and "n"), a double, a color (specified by the syntax
1602 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1603 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1604 description), a position (specified by the syntax @var{X}/@var{Y},
1605 @var{X} and @var{Y} being float numbers) and a string.
1607 The number and kind of parameters depend on the loaded effect. If an
1608 effect parameter is not specified the default value is set.
1610 Some examples follow:
1612 # apply the distort0r effect, set the first two double parameters
1613 frei0r=distort0r:0.5:0.01
1615 # apply the colordistance effect, takes a color as first parameter
1616 frei0r=colordistance:0.2/0.3/0.4
1617 frei0r=colordistance:violet
1618 frei0r=colordistance:0x112233
1620 # apply the perspective effect, specify the top left and top right
1622 frei0r=perspective:0.2/0.2:0.8/0.2
1625 For more information see:
1626 @url{http://piksel.org/frei0r}
1630 Fix the banding artifacts that are sometimes introduced into nearly flat
1631 regions by truncation to 8bit color depth.
1632 Interpolate the gradients that should go where the bands are, and
1635 This filter is designed for playback only. Do not use it prior to
1636 lossy compression, because compression tends to lose the dither and
1637 bring back the bands.
1639 The filter takes two optional parameters, separated by ':':
1640 @var{strength}:@var{radius}
1642 @var{strength} is the maximum amount by which the filter will change
1643 any one pixel. Also the threshold for detecting nearly flat
1644 regions. Acceptable values range from .51 to 255, default value is
1645 1.2, out-of-range values will be clipped to the valid range.
1647 @var{radius} is the neighborhood to fit the gradient to. A larger
1648 radius makes for smoother gradients, but also prevents the filter from
1649 modifying the pixels near detailed regions. Acceptable values are
1650 8-32, default value is 16, out-of-range values will be clipped to the
1654 # default parameters
1663 Flip the input video horizontally.
1665 For example to horizontally flip the input video with @command{ffmpeg}:
1667 ffmpeg -i in.avi -vf "hflip" out.avi
1672 High precision/quality 3d denoise filter. This filter aims to reduce
1673 image noise producing smooth images and making still images really
1674 still. It should enhance compressibility.
1676 It accepts the following optional parameters:
1677 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1681 a non-negative float number which specifies spatial luma strength,
1684 @item chroma_spatial
1685 a non-negative float number which specifies spatial chroma strength,
1686 defaults to 3.0*@var{luma_spatial}/4.0
1689 a float number which specifies luma temporal strength, defaults to
1690 6.0*@var{luma_spatial}/4.0
1693 a float number which specifies chroma temporal strength, defaults to
1694 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1697 @section lut, lutrgb, lutyuv
1699 Compute a look-up table for binding each pixel component input value
1700 to an output value, and apply it to input video.
1702 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1703 to an RGB input video.
1705 These filters accept in input a ":"-separated list of options, which
1706 specify the expressions used for computing the lookup table for the
1707 corresponding pixel component values.
1709 The @var{lut} filter requires either YUV or RGB pixel formats in
1710 input, and accepts the options:
1713 first pixel component
1715 second pixel component
1717 third pixel component
1719 fourth pixel component, corresponds to the alpha component
1722 The exact component associated to each option depends on the format in
1725 The @var{lutrgb} filter requires RGB pixel formats in input, and
1726 accepts the options:
1738 The @var{lutyuv} filter requires YUV pixel formats in input, and
1739 accepts the options:
1742 Y/luminance component
1751 The expressions can contain the following constants and functions:
1755 the input width and height
1758 input value for the pixel component
1761 the input value clipped in the @var{minval}-@var{maxval} range
1764 maximum value for the pixel component
1767 minimum value for the pixel component
1770 the negated value for the pixel component value clipped in the
1771 @var{minval}-@var{maxval} range , it corresponds to the expression
1772 "maxval-clipval+minval"
1775 the computed value in @var{val} clipped in the
1776 @var{minval}-@var{maxval} range
1778 @item gammaval(gamma)
1779 the computed gamma correction value of the pixel component value
1780 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1782 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1786 All expressions default to "val".
1788 Some examples follow:
1790 # negate input video
1791 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1792 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1794 # the above is the same as
1795 lutrgb="r=negval:g=negval:b=negval"
1796 lutyuv="y=negval:u=negval:v=negval"
1801 # remove chroma components, turns the video into a graytone image
1802 lutyuv="u=128:v=128"
1804 # apply a luma burning effect
1807 # remove green and blue components
1810 # set a constant alpha channel value on input
1811 format=rgba,lutrgb=a="maxval-minval/2"
1813 # correct luminance gamma by a 0.5 factor
1814 lutyuv=y=gammaval(0.5)
1819 Apply an MPlayer filter to the input video.
1821 This filter provides a wrapper around most of the filters of
1824 This wrapper is considered experimental. Some of the wrapped filters
1825 may not work properly and we may drop support for them, as they will
1826 be implemented natively into FFmpeg. Thus you should avoid
1827 depending on them when writing portable scripts.
1829 The filters accepts the parameters:
1830 @var{filter_name}[:=]@var{filter_params}
1832 @var{filter_name} is the name of a supported MPlayer filter,
1833 @var{filter_params} is a string containing the parameters accepted by
1836 The list of the currently supported filters follows:
1889 The parameter syntax and behavior for the listed filters are the same
1890 of the corresponding MPlayer filters. For detailed instructions check
1891 the "VIDEO FILTERS" section in the MPlayer manual.
1893 Some examples follow:
1895 # remove a logo by interpolating the surrounding pixels
1896 mp=delogo=200:200:80:20:1
1898 # adjust gamma, brightness, contrast
1901 # tweak hue and saturation
1905 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1911 This filter accepts an integer in input, if non-zero it negates the
1912 alpha component (if available). The default value in input is 0.
1916 Force libavfilter not to use any of the specified pixel formats for the
1917 input to the next filter.
1919 The filter accepts a list of pixel format names, separated by ":",
1920 for example "yuv420p:monow:rgb24".
1922 Some examples follow:
1924 # force libavfilter to use a format different from "yuv420p" for the
1925 # input to the vflip filter
1926 noformat=yuv420p,vflip
1928 # convert the input video to any of the formats not contained in the list
1929 noformat=yuv420p:yuv444p:yuv410p
1934 Pass the video source unchanged to the output.
1938 Apply video transform using libopencv.
1940 To enable this filter install libopencv library and headers and
1941 configure FFmpeg with @code{--enable-libopencv}.
1943 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1945 @var{filter_name} is the name of the libopencv filter to apply.
1947 @var{filter_params} specifies the parameters to pass to the libopencv
1948 filter. If not specified the default values are assumed.
1950 Refer to the official libopencv documentation for more precise
1952 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1954 Follows the list of supported libopencv filters.
1959 Dilate an image by using a specific structuring element.
1960 This filter corresponds to the libopencv function @code{cvDilate}.
1962 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1964 @var{struct_el} represents a structuring element, and has the syntax:
1965 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1967 @var{cols} and @var{rows} represent the number of columns and rows of
1968 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1969 point, and @var{shape} the shape for the structuring element, and
1970 can be one of the values "rect", "cross", "ellipse", "custom".
1972 If the value for @var{shape} is "custom", it must be followed by a
1973 string of the form "=@var{filename}". The file with name
1974 @var{filename} is assumed to represent a binary image, with each
1975 printable character corresponding to a bright pixel. When a custom
1976 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1977 or columns and rows of the read file are assumed instead.
1979 The default value for @var{struct_el} is "3x3+0x0/rect".
1981 @var{nb_iterations} specifies the number of times the transform is
1982 applied to the image, and defaults to 1.
1984 Follow some example:
1986 # use the default values
1989 # dilate using a structuring element with a 5x5 cross, iterate two times
1990 ocv=dilate=5x5+2x2/cross:2
1992 # read the shape from the file diamond.shape, iterate two times
1993 # the file diamond.shape may contain a pattern of characters like this:
1999 # the specified cols and rows are ignored (but not the anchor point coordinates)
2000 ocv=0x0+2x2/custom=diamond.shape:2
2005 Erode an image by using a specific structuring element.
2006 This filter corresponds to the libopencv function @code{cvErode}.
2008 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
2009 with the same syntax and semantics as the @ref{dilate} filter.
2013 Smooth the input video.
2015 The filter takes the following parameters:
2016 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
2018 @var{type} is the type of smooth filter to apply, and can be one of
2019 the following values: "blur", "blur_no_scale", "median", "gaussian",
2020 "bilateral". The default value is "gaussian".
2022 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
2023 parameters whose meanings depend on smooth type. @var{param1} and
2024 @var{param2} accept integer positive values or 0, @var{param3} and
2025 @var{param4} accept float values.
2027 The default value for @var{param1} is 3, the default value for the
2028 other parameters is 0.
2030 These parameters correspond to the parameters assigned to the
2031 libopencv function @code{cvSmooth}.
2036 Overlay one video on top of another.
2038 It takes two inputs and one output, the first input is the "main"
2039 video on which the second input is overlayed.
2041 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
2043 @var{x} is the x coordinate of the overlayed video on the main video,
2044 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
2045 the following parameters:
2048 @item main_w, main_h
2049 main input width and height
2052 same as @var{main_w} and @var{main_h}
2054 @item overlay_w, overlay_h
2055 overlay input width and height
2058 same as @var{overlay_w} and @var{overlay_h}
2061 @var{options} is an optional list of @var{key}=@var{value} pairs,
2064 The description of the accepted options follows.
2068 If set to 1, force the filter to accept inputs in the RGB
2069 color space. Default value is 0.
2072 Be aware that frames are taken from each input video in timestamp
2073 order, hence, if their initial timestamps differ, it is a a good idea
2074 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
2075 have them begin in the same zero timestamp, as it does the example for
2076 the @var{movie} filter.
2078 Follow some examples:
2080 # draw the overlay at 10 pixels from the bottom right
2081 # corner of the main video.
2082 overlay=main_w-overlay_w-10:main_h-overlay_h-10
2084 # insert a transparent PNG logo in the bottom left corner of the input
2085 movie=logo.png [logo];
2086 [in][logo] overlay=10:main_h-overlay_h-10 [out]
2088 # insert 2 different transparent PNG logos (second logo on bottom
2090 movie=logo1.png [logo1];
2091 movie=logo2.png [logo2];
2092 [in][logo1] overlay=10:H-h-10 [in+logo1];
2093 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
2095 # add a transparent color layer on top of the main video,
2096 # WxH specifies the size of the main input to the overlay filter
2097 color=red@.3:WxH [over]; [in][over] overlay [out]
2100 You can chain together more overlays but the efficiency of such
2101 approach is yet to be tested.
2105 Add paddings to the input image, and places the original input at the
2106 given coordinates @var{x}, @var{y}.
2108 It accepts the following parameters:
2109 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
2111 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
2112 expressions containing the following constants:
2116 the input video width and height
2119 same as @var{in_w} and @var{in_h}
2122 the output width and height, that is the size of the padded area as
2123 specified by the @var{width} and @var{height} expressions
2126 same as @var{out_w} and @var{out_h}
2129 x and y offsets as specified by the @var{x} and @var{y}
2130 expressions, or NAN if not yet specified
2133 same as @var{iw} / @var{ih}
2136 input sample aspect ratio
2139 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2142 horizontal and vertical chroma subsample values. For example for the
2143 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2146 Follows the description of the accepted parameters.
2151 Specify the size of the output image with the paddings added. If the
2152 value for @var{width} or @var{height} is 0, the corresponding input size
2153 is used for the output.
2155 The @var{width} expression can reference the value set by the
2156 @var{height} expression, and vice versa.
2158 The default value of @var{width} and @var{height} is 0.
2162 Specify the offsets where to place the input image in the padded area
2163 with respect to the top/left border of the output image.
2165 The @var{x} expression can reference the value set by the @var{y}
2166 expression, and vice versa.
2168 The default value of @var{x} and @var{y} is 0.
2172 Specify the color of the padded area, it can be the name of a color
2173 (case insensitive match) or a 0xRRGGBB[AA] sequence.
2175 The default value of @var{color} is "black".
2179 Some examples follow:
2182 # Add paddings with color "violet" to the input video. Output video
2183 # size is 640x480, the top-left corner of the input video is placed at
2185 pad=640:480:0:40:violet
2187 # pad the input to get an output with dimensions increased bt 3/2,
2188 # and put the input video at the center of the padded area
2189 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2191 # pad the input to get a squared output with size equal to the maximum
2192 # value between the input width and height, and put the input video at
2193 # the center of the padded area
2194 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2196 # pad the input to get a final w/h ratio of 16:9
2197 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2199 # for anamorphic video, in order to set the output display aspect ratio,
2200 # it is necessary to use sar in the expression, according to the relation:
2201 # (ih * X / ih) * sar = output_dar
2202 # X = output_dar / sar
2203 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
2205 # double output size and put the input video in the bottom-right
2206 # corner of the output padded area
2207 pad="2*iw:2*ih:ow-iw:oh-ih"
2210 @section pixdesctest
2212 Pixel format descriptor test filter, mainly useful for internal
2213 testing. The output video should be equal to the input video.
2217 format=monow, pixdesctest
2220 can be used to test the monowhite pixel format descriptor definition.
2224 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
2226 The scale filter forces the output display aspect ratio to be the same
2227 of the input, by changing the output sample aspect ratio.
2229 The parameters @var{width} and @var{height} are expressions containing
2230 the following constants:
2234 the input width and height
2237 same as @var{in_w} and @var{in_h}
2240 the output (cropped) width and height
2243 same as @var{out_w} and @var{out_h}
2246 same as @var{iw} / @var{ih}
2249 input sample aspect ratio
2252 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2255 horizontal and vertical chroma subsample values. For example for the
2256 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2259 If the input image format is different from the format requested by
2260 the next filter, the scale filter will convert the input to the
2263 If the value for @var{width} or @var{height} is 0, the respective input
2264 size is used for the output.
2266 If the value for @var{width} or @var{height} is -1, the scale filter will
2267 use, for the respective output size, a value that maintains the aspect
2268 ratio of the input image.
2270 The default value of @var{width} and @var{height} is 0.
2272 Valid values for the optional parameter @var{interl} are:
2276 force interlaced aware scaling
2279 select interlaced aware scaling depending on whether the source frames
2280 are flagged as interlaced or not
2283 Some examples follow:
2285 # scale the input video to a size of 200x100.
2288 # scale the input to 2x
2290 # the above is the same as
2293 # scale the input to half size
2296 # increase the width, and set the height to the same size
2299 # seek for Greek harmony
2303 # increase the height, and set the width to 3/2 of the height
2306 # increase the size, but make the size a multiple of the chroma
2307 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2309 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2310 scale='min(500\, iw*3/2):-1'
2314 Select frames to pass in output.
2316 It accepts in input an expression, which is evaluated for each input
2317 frame. If the expression is evaluated to a non-zero value, the frame
2318 is selected and passed to the output, otherwise it is discarded.
2320 The expression can contain the following constants:
2324 the sequential number of the filtered frame, starting from 0
2327 the sequential number of the selected frame, starting from 0
2329 @item prev_selected_n
2330 the sequential number of the last selected frame, NAN if undefined
2333 timebase of the input timestamps
2336 the PTS (Presentation TimeStamp) of the filtered video frame,
2337 expressed in @var{TB} units, NAN if undefined
2340 the PTS (Presentation TimeStamp) of the filtered video frame,
2341 expressed in seconds, NAN if undefined
2344 the PTS of the previously filtered video frame, NAN if undefined
2346 @item prev_selected_pts
2347 the PTS of the last previously filtered video frame, NAN if undefined
2349 @item prev_selected_t
2350 the PTS of the last previously selected video frame, NAN if undefined
2353 the PTS of the first video frame in the video, NAN if undefined
2356 the time of the first video frame in the video, NAN if undefined
2359 the type of the filtered frame, can assume one of the following
2371 @item interlace_type
2372 the frame interlace type, can assume one of the following values:
2375 the frame is progressive (not interlaced)
2377 the frame is top-field-first
2379 the frame is bottom-field-first
2383 1 if the filtered frame is a key-frame, 0 otherwise
2386 the position in the file of the filtered frame, -1 if the information
2387 is not available (e.g. for synthetic video)
2390 The default value of the select expression is "1".
2392 Some examples follow:
2395 # select all frames in input
2398 # the above is the same as:
2404 # select only I-frames
2405 select='eq(pict_type\,I)'
2407 # select one frame every 100
2408 select='not(mod(n\,100))'
2410 # select only frames contained in the 10-20 time interval
2411 select='gte(t\,10)*lte(t\,20)'
2413 # select only I frames contained in the 10-20 time interval
2414 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2416 # select frames with a minimum distance of 10 seconds
2417 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2420 @section setdar, setsar
2422 The @code{setdar} filter sets the Display Aspect Ratio for the filter
2425 This is done by changing the specified Sample (aka Pixel) Aspect
2426 Ratio, according to the following equation:
2428 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
2431 Keep in mind that the @code{setdar} filter does not modify the pixel
2432 dimensions of the video frame. Also the display aspect ratio set by
2433 this filter may be changed by later filters in the filterchain,
2434 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
2437 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
2438 the filter output video.
2440 Note that as a consequence of the application of this filter, the
2441 output display aspect ratio will change according to the equation
2444 Keep in mind that the sample aspect ratio set by the @code{setsar}
2445 filter may be changed by later filters in the filterchain, e.g. if
2446 another "setsar" or a "setdar" filter is applied.
2448 The @code{setdar} and @code{setsar} filters accept a parameter string
2449 which represents the wanted aspect ratio. The parameter can
2450 be a floating point number string, an expression, or a string of the form
2451 @var{num}:@var{den}, where @var{num} and @var{den} are the numerator
2452 and denominator of the aspect ratio. If the parameter is not
2453 specified, it is assumed the value "0:1".
2455 For example to change the display aspect ratio to 16:9, specify:
2460 The example above is equivalent to:
2465 To change the sample aspect ratio to 10:11, specify:
2472 Force field for the output video frame.
2474 The @code{setfield} filter marks the interlace type field for the
2475 output frames. It does not change the input frame, but only sets the
2476 corresponding property, which affects how the frame is treated by
2477 followig filters (e.g. @code{fieldorder} or @code{yadif}).
2479 It accepts a parameter representing an integer or a string, which can
2480 assume the following values:
2483 Keep the same field property.
2486 Mark the frame as bottom-field-first.
2489 Mark the frame as top-field-first.
2494 Change the PTS (presentation timestamp) of the input video frames.
2496 Accept in input an expression evaluated through the eval API, which
2497 can contain the following constants:
2501 the presentation timestamp in input
2504 the count of the input frame, starting from 0.
2507 the PTS of the first video frame
2510 tell if the current frame is interlaced
2513 original position in the file of the frame, or undefined if undefined
2514 for the current frame
2524 Some examples follow:
2527 # start counting PTS from zero
2539 # fixed rate 25 fps with some jitter
2540 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2545 Set the timebase to use for the output frames timestamps.
2546 It is mainly useful for testing timebase configuration.
2548 It accepts in input an arithmetic expression representing a rational.
2549 The expression can contain the constants "AVTB" (the
2550 default timebase), and "intb" (the input timebase).
2552 The default value for the input is "intb".
2554 Follow some examples.
2557 # set the timebase to 1/25
2560 # set the timebase to 1/10
2563 #set the timebase to 1001/1000
2566 #set the timebase to 2*intb
2569 #set the default timebase value
2575 Show a line containing various information for each input video frame.
2576 The input video is not modified.
2578 The shown line contains a sequence of key/value pairs of the form
2579 @var{key}:@var{value}.
2581 A description of each shown parameter follows:
2585 sequential number of the input frame, starting from 0
2588 Presentation TimeStamp of the input frame, expressed as a number of
2589 time base units. The time base unit depends on the filter input pad.
2592 Presentation TimeStamp of the input frame, expressed as a number of
2596 position of the frame in the input stream, -1 if this information in
2597 unavailable and/or meaningless (for example in case of synthetic video)
2603 sample aspect ratio of the input frame, expressed in the form
2607 size of the input frame, expressed in the form
2608 @var{width}x@var{height}
2611 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2612 for bottom field first)
2615 1 if the frame is a key frame, 0 otherwise
2618 picture type of the input frame ("I" for an I-frame, "P" for a
2619 P-frame, "B" for a B-frame, "?" for unknown type).
2620 Check also the documentation of the @code{AVPictureType} enum and of
2621 the @code{av_get_picture_type_char} function defined in
2622 @file{libavutil/avutil.h}.
2625 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2627 @item plane_checksum
2628 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2629 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2634 Pass the images of input video on to next video filter as multiple
2638 ffmpeg -i in.avi -vf "slicify=32" out.avi
2641 The filter accepts the slice height as parameter. If the parameter is
2642 not specified it will use the default value of 16.
2644 Adding this in the beginning of filter chains should make filtering
2645 faster due to better use of the memory cache.
2649 Pass on the input video to two outputs. Both outputs are identical to
2654 [in] split [splitout1][splitout2];
2655 [splitout1] crop=100:100:0:0 [cropout];
2656 [splitout2] pad=200:200:100:100 [padout];
2659 will create two separate outputs from the same input, one cropped and
2666 Select the most representative frame in a given sequence of consecutive frames.
2668 It accepts as argument the frames batch size to analyze (default @var{N}=100);
2669 in a set of @var{N} frames, the filter will pick one of them, and then handle
2670 the next batch of @var{N} frames until the end.
2672 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
2673 value will result in a higher memory usage, so a high value is not recommended.
2675 The following example extract one picture each 50 frames:
2680 Complete example of a thumbnail creation with @command{ffmpeg}:
2682 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
2687 Tile several successive frames together.
2689 It accepts as argument the tile size (i.e. the number of lines and columns)
2690 in the form "@var{w}x@var{h}".
2692 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
2695 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
2697 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
2698 duplicating each output frame to accomodate the originally detected frame
2703 Perform various types of temporal field interlacing.
2705 Frames are counted starting from 1, so the first input frame is
2708 This filter accepts a single parameter specifying the mode. Available
2713 Move odd frames into the upper field, even into the lower field,
2714 generating a double height frame at half framerate.
2717 Only output even frames, odd frames are dropped, generating a frame with
2718 unchanged height at half framerate.
2721 Only output odd frames, even frames are dropped, generating a frame with
2722 unchanged height at half framerate.
2725 Expand each frame to full height, but pad alternate lines with black,
2726 generating a frame with double height at the same input framerate.
2729 Interleave the upper field from odd frames with the lower field from
2730 even frames, generating a frame with unchanged height at half framerate.
2733 Interleave the lower field from odd frames with the upper field from
2734 even frames, generating a frame with unchanged height at half framerate.
2741 Transpose rows with columns in the input video and optionally flip it.
2743 It accepts a parameter representing an integer, which can assume the
2748 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2756 Rotate by 90 degrees clockwise, that is:
2764 Rotate by 90 degrees counterclockwise, that is:
2772 Rotate by 90 degrees clockwise and vertically flip, that is:
2782 Sharpen or blur the input video.
2784 It accepts the following parameters:
2785 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2787 Negative values for the amount will blur the input video, while positive
2788 values will sharpen. All parameters are optional and default to the
2789 equivalent of the string '5:5:1.0:5:5:0.0'.
2794 Set the luma matrix horizontal size. It can be an integer between 3
2795 and 13, default value is 5.
2798 Set the luma matrix vertical size. It can be an integer between 3
2799 and 13, default value is 5.
2802 Set the luma effect strength. It can be a float number between -2.0
2803 and 5.0, default value is 1.0.
2805 @item chroma_msize_x
2806 Set the chroma matrix horizontal size. It can be an integer between 3
2807 and 13, default value is 5.
2809 @item chroma_msize_y
2810 Set the chroma matrix vertical size. It can be an integer between 3
2811 and 13, default value is 5.
2814 Set the chroma effect strength. It can be a float number between -2.0
2815 and 5.0, default value is 0.0.
2820 # Strong luma sharpen effect parameters
2823 # Strong blur of both luma and chroma parameters
2824 unsharp=7:7:-2:7:7:-2
2826 # Use the default values with @command{ffmpeg}
2827 ffmpeg -i in.avi -vf "unsharp" out.mp4
2832 Flip the input video vertically.
2835 ffmpeg -i in.avi -vf "vflip" out.avi
2840 Deinterlace the input video ("yadif" means "yet another deinterlacing
2843 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2845 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2850 output 1 frame for each frame
2852 output 1 frame for each field
2854 like 0 but skips spatial interlacing check
2856 like 1 but skips spatial interlacing check
2861 @var{parity} specifies the picture field parity assumed for the input
2862 interlaced video, accepts one of the following values:
2866 assume top field first
2868 assume bottom field first
2870 enable automatic detection
2873 Default value is -1.
2874 If interlacing is unknown or decoder does not export this information,
2875 top field first will be assumed.
2877 @var{auto} specifies if deinterlacer should trust the interlaced flag
2878 and only deinterlace frames marked as interlaced
2882 deinterlace all frames
2884 only deinterlace frames marked as interlaced
2889 @c man end VIDEO FILTERS
2891 @chapter Video Sources
2892 @c man begin VIDEO SOURCES
2894 Below is a description of the currently available video sources.
2898 Buffer video frames, and make them available to the filter chain.
2900 This source is mainly intended for a programmatic use, in particular
2901 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2903 It accepts the following parameters:
2904 @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}
2906 All the parameters but @var{scale_params} need to be explicitly
2909 Follows the list of the accepted parameters.
2914 Specify the width and height of the buffered video frames.
2916 @item pix_fmt_string
2917 A string representing the pixel format of the buffered video frames.
2918 It may be a number corresponding to a pixel format, or a pixel format
2921 @item timebase_num, timebase_den
2922 Specify numerator and denomitor of the timebase assumed by the
2923 timestamps of the buffered frames.
2925 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2926 Specify numerator and denominator of the sample aspect ratio assumed
2927 by the video frames.
2930 Specify the optional parameters to be used for the scale filter which
2931 is automatically inserted when an input change is detected in the
2932 input size or format.
2937 buffer=320:240:yuv410p:1:24:1:1
2940 will instruct the source to accept video frames with size 320x240 and
2941 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2942 square pixels (1:1 sample aspect ratio).
2943 Since the pixel format with name "yuv410p" corresponds to the number 6
2944 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2945 this example corresponds to:
2947 buffer=320:240:6:1:24:1:1
2952 Create a pattern generated by an elementary cellular automaton.
2954 The initial state of the cellular automaton can be defined through the
2955 @option{filename}, and @option{pattern} options. If such options are
2956 not specified an initial state is created randomly.
2958 At each new frame a new row in the video is filled with the result of
2959 the cellular automaton next generation. The behavior when the whole
2960 frame is filled is defined by the @option{scroll} option.
2962 This source accepts a list of options in the form of
2963 @var{key}=@var{value} pairs separated by ":". A description of the
2964 accepted options follows.
2968 Read the initial cellular automaton state, i.e. the starting row, from
2970 In the file, each non-whitespace character is considered an alive
2971 cell, a newline will terminate the row, and further characters in the
2972 file will be ignored.
2975 Read the initial cellular automaton state, i.e. the starting row, from
2976 the specified string.
2978 Each non-whitespace character in the string is considered an alive
2979 cell, a newline will terminate the row, and further characters in the
2980 string will be ignored.
2983 Set the video rate, that is the number of frames generated per second.
2986 @item random_fill_ratio, ratio
2987 Set the random fill ratio for the initial cellular automaton row. It
2988 is a floating point number value ranging from 0 to 1, defaults to
2991 This option is ignored when a file or a pattern is specified.
2993 @item random_seed, seed
2994 Set the seed for filling randomly the initial row, must be an integer
2995 included between 0 and UINT32_MAX. If not specified, or if explicitly
2996 set to -1, the filter will try to use a good random seed on a best
3000 Set the cellular automaton rule, it is a number ranging from 0 to 255.
3001 Default value is 110.
3004 Set the size of the output video.
3006 If @option{filename} or @option{pattern} is specified, the size is set
3007 by default to the width of the specified initial state row, and the
3008 height is set to @var{width} * PHI.
3010 If @option{size} is set, it must contain the width of the specified
3011 pattern string, and the specified pattern will be centered in the
3014 If a filename or a pattern string is not specified, the size value
3015 defaults to "320x518" (used for a randomly generated initial state).
3018 If set to 1, scroll the output upward when all the rows in the output
3019 have been already filled. If set to 0, the new generated row will be
3020 written over the top row just after the bottom row is filled.
3023 @item start_full, full
3024 If set to 1, completely fill the output with generated rows before
3025 outputting the first frame.
3026 This is the default behavior, for disabling set the value to 0.
3029 If set to 1, stitch the left and right row edges together.
3030 This is the default behavior, for disabling set the value to 0.
3033 @subsection Examples
3037 Read the initial state from @file{pattern}, and specify an output of
3040 cellauto=f=pattern:s=200x400
3044 Generate a random initial row with a width of 200 cells, with a fill
3047 cellauto=ratio=2/3:s=200x200
3051 Create a pattern generated by rule 18 starting by a single alive cell
3052 centered on an initial row with width 100:
3054 cellauto=p=@@:s=100x400:full=0:rule=18
3058 Specify a more elaborated initial pattern:
3060 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
3067 Provide an uniformly colored input.
3069 It accepts the following parameters:
3070 @var{color}:@var{frame_size}:@var{frame_rate}
3072 Follows the description of the accepted parameters.
3077 Specify the color of the source. It can be the name of a color (case
3078 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
3079 alpha specifier. The default value is "black".
3082 Specify the size of the sourced video, it may be a string of the form
3083 @var{width}x@var{height}, or the name of a size abbreviation. The
3084 default value is "320x240".
3087 Specify the frame rate of the sourced video, as the number of frames
3088 generated per second. It has to be a string in the format
3089 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3090 number or a valid video frame rate abbreviation. The default value is
3095 For example the following graph description will generate a red source
3096 with an opacity of 0.2, with size "qcif" and a frame rate of 10
3097 frames per second, which will be overlayed over the source connected
3098 to the pad with identifier "in".
3101 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
3106 Read a video stream from a movie container.
3108 It accepts the syntax: @var{movie_name}[:@var{options}] where
3109 @var{movie_name} is the name of the resource to read (not necessarily
3110 a file but also a device or a stream accessed through some protocol),
3111 and @var{options} is an optional sequence of @var{key}=@var{value}
3112 pairs, separated by ":".
3114 The description of the accepted options follows.
3118 @item format_name, f
3119 Specifies the format assumed for the movie to read, and can be either
3120 the name of a container or an input device. If not specified the
3121 format is guessed from @var{movie_name} or by probing.
3123 @item seek_point, sp
3124 Specifies the seek point in seconds, the frames will be output
3125 starting from this seek point, the parameter is evaluated with
3126 @code{av_strtod} so the numerical value may be suffixed by an IS
3127 postfix. Default value is "0".
3129 @item stream_index, si
3130 Specifies the index of the video stream to read. If the value is -1,
3131 the best suited video stream will be automatically selected. Default
3135 Specifies how many times to read the video stream in sequence.
3136 If the value is less than 1, the stream will be read again and again.
3137 Default value is "1".
3139 Note that when the movie is looped the source timestamps are not
3140 changed, so it will generate non monotonically increasing timestamps.
3143 This filter allows to overlay a second video on top of main input of
3144 a filtergraph as shown in this graph:
3146 input -----------> deltapts0 --> overlay --> output
3149 movie --> scale--> deltapts1 -------+
3152 Some examples follow:
3154 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
3155 # on top of the input labelled as "in".
3156 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3157 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3159 # read from a video4linux2 device, and overlay it on top of the input
3161 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3162 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3168 Generate various test patterns, as generated by the MPlayer test filter.
3170 The size of the generated video is fixed, and is 256x256.
3171 This source is useful in particular for testing encoding features.
3173 This source accepts an optional sequence of @var{key}=@var{value} pairs,
3174 separated by ":". The description of the accepted options follows.
3179 Specify the frame rate of the sourced video, as the number of frames
3180 generated per second. It has to be a string in the format
3181 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3182 number or a valid video frame rate abbreviation. The default value is
3186 Set the video duration of the sourced video. The accepted syntax is:
3188 [-]HH[:MM[:SS[.m...]]]
3191 See also the function @code{av_parse_time()}.
3193 If not specified, or the expressed duration is negative, the video is
3194 supposed to be generated forever.
3198 Set the number or the name of the test to perform. Supported tests are:
3213 Default value is "all", which will cycle through the list of all tests.
3216 For example the following:
3221 will generate a "dc_luma" test pattern.
3225 Provide a frei0r source.
3227 To enable compilation of this filter you need to install the frei0r
3228 header and configure FFmpeg with @code{--enable-frei0r}.
3230 The source supports the syntax:
3232 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
3235 @var{size} is the size of the video to generate, may be a string of the
3236 form @var{width}x@var{height} or a frame size abbreviation.
3237 @var{rate} is the rate of the video to generate, may be a string of
3238 the form @var{num}/@var{den} or a frame rate abbreviation.
3239 @var{src_name} is the name to the frei0r source to load. For more
3240 information regarding frei0r and how to set the parameters read the
3241 section @ref{frei0r} in the description of the video filters.
3243 Some examples follow:
3245 # generate a frei0r partik0l source with size 200x200 and frame rate 10
3246 # which is overlayed on the overlay filter main input
3247 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
3252 Generate a life pattern.
3254 This source is based on a generalization of John Conway's life game.
3256 The sourced input represents a life grid, each pixel represents a cell
3257 which can be in one of two possible states, alive or dead. Every cell
3258 interacts with its eight neighbours, which are the cells that are
3259 horizontally, vertically, or diagonally adjacent.
3261 At each interaction the grid evolves according to the adopted rule,
3262 which specifies the number of neighbor alive cells which will make a
3263 cell stay alive or born. The @option{rule} option allows to specify
3266 This source accepts a list of options in the form of
3267 @var{key}=@var{value} pairs separated by ":". A description of the
3268 accepted options follows.
3272 Set the file from which to read the initial grid state. In the file,
3273 each non-whitespace character is considered an alive cell, and newline
3274 is used to delimit the end of each row.
3276 If this option is not specified, the initial grid is generated
3280 Set the video rate, that is the number of frames generated per second.
3283 @item random_fill_ratio, ratio
3284 Set the random fill ratio for the initial random grid. It is a
3285 floating point number value ranging from 0 to 1, defaults to 1/PHI.
3286 It is ignored when a file is specified.
3288 @item random_seed, seed
3289 Set the seed for filling the initial random grid, must be an integer
3290 included between 0 and UINT32_MAX. If not specified, or if explicitly
3291 set to -1, the filter will try to use a good random seed on a best
3297 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
3298 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
3299 @var{NS} specifies the number of alive neighbor cells which make a
3300 live cell stay alive, and @var{NB} the number of alive neighbor cells
3301 which make a dead cell to become alive (i.e. to "born").
3302 "s" and "b" can be used in place of "S" and "B", respectively.
3304 Alternatively a rule can be specified by an 18-bits integer. The 9
3305 high order bits are used to encode the next cell state if it is alive
3306 for each number of neighbor alive cells, the low order bits specify
3307 the rule for "borning" new cells. Higher order bits encode for an
3308 higher number of neighbor cells.
3309 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
3310 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
3312 Default value is "S23/B3", which is the original Conway's game of life
3313 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
3314 cells, and will born a new cell if there are three alive cells around
3318 Set the size of the output video.
3320 If @option{filename} is specified, the size is set by default to the
3321 same size of the input file. If @option{size} is set, it must contain
3322 the size specified in the input file, and the initial grid defined in
3323 that file is centered in the larger resulting area.
3325 If a filename is not specified, the size value defaults to "320x240"
3326 (used for a randomly generated initial grid).
3329 If set to 1, stitch the left and right grid edges together, and the
3330 top and bottom edges also. Defaults to 1.
3333 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
3334 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
3335 value from 0 to 255.
3338 Set the color of living (or new born) cells.
3341 Set the color of dead cells. If @option{mold} is set, this is the first color
3342 used to represent a dead cell.
3345 Set mold color, for definitely dead and moldy cells.
3348 @subsection Examples
3352 Read a grid from @file{pattern}, and center it on a grid of size
3355 life=f=pattern:s=300x300
3359 Generate a random grid of size 200x200, with a fill ratio of 2/3:
3361 life=ratio=2/3:s=200x200
3365 Specify a custom rule for evolving a randomly generated grid:
3371 Full example with slow death effect (mold) using @command{ffplay}:
3373 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
3377 @section nullsrc, rgbtestsrc, testsrc
3379 The @code{nullsrc} source returns unprocessed video frames. It is
3380 mainly useful to be employed in analysis / debugging tools, or as the
3381 source for filters which ignore the input data.
3383 The @code{rgbtestsrc} source generates an RGB test pattern useful for
3384 detecting RGB vs BGR issues. You should see a red, green and blue
3385 stripe from top to bottom.
3387 The @code{testsrc} source generates a test video pattern, showing a
3388 color pattern, a scrolling gradient and a timestamp. This is mainly
3389 intended for testing purposes.
3391 These sources accept an optional sequence of @var{key}=@var{value} pairs,
3392 separated by ":". The description of the accepted options follows.
3397 Specify the size of the sourced video, it may be a string of the form
3398 @var{width}x@var{height}, or the name of a size abbreviation. The
3399 default value is "320x240".
3402 Specify the frame rate of the sourced video, as the number of frames
3403 generated per second. It has to be a string in the format
3404 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3405 number or a valid video frame rate abbreviation. The default value is
3409 Set the sample aspect ratio of the sourced video.
3412 Set the video duration of the sourced video. The accepted syntax is:
3414 [-]HH[:MM[:SS[.m...]]]
3417 See also the function @code{av_parse_time()}.
3419 If not specified, or the expressed duration is negative, the video is
3420 supposed to be generated forever.
3423 Set the number of decimals to show in the timestamp, only used in the
3424 @code{testsrc} source.
3426 The displayed timestamp value will correspond to the original
3427 timestamp value multiplied by the power of 10 of the specified
3428 value. Default value is 0.
3431 For example the following:
3433 testsrc=duration=5.3:size=qcif:rate=10
3436 will generate a video with a duration of 5.3 seconds, with size
3437 176x144 and a frame rate of 10 frames per second.
3439 If the input content is to be ignored, @code{nullsrc} can be used. The
3440 following command generates noise in the luminance plane by employing
3441 the @code{mp=geq} filter:
3443 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
3446 @c man end VIDEO SOURCES
3448 @chapter Video Sinks
3449 @c man begin VIDEO SINKS
3451 Below is a description of the currently available video sinks.
3455 Buffer video frames, and make them available to the end of the filter
3458 This sink is mainly intended for a programmatic use, in particular
3459 through the interface defined in @file{libavfilter/buffersink.h}.
3461 It does not require a string parameter in input, but you need to
3462 specify a pointer to a list of supported pixel formats terminated by
3463 -1 in the opaque parameter provided to @code{avfilter_init_filter}
3464 when initializing this sink.
3468 Null video sink, do absolutely nothing with the input video. It is
3469 mainly useful as a template and to be employed in analysis / debugging
3472 @c man end VIDEO SINKS