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 @anchor{Filtergraph syntax}
18 @section Filtergraph syntax
20 A filtergraph can be represented using a textual representation, which is
21 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
22 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
23 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
24 @file{libavfilter/avfiltergraph.h}.
26 A filterchain consists of a sequence of connected filters, each one
27 connected to the previous one in the sequence. A filterchain is
28 represented by a list of ","-separated filter descriptions.
30 A filtergraph consists of a sequence of filterchains. A sequence of
31 filterchains is represented by a list of ";"-separated filterchain
34 A filter is represented by a string of the form:
35 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
37 @var{filter_name} is the name of the filter class of which the
38 described filter is an instance of, and has to be the name of one of
39 the filter classes registered in the program.
40 The name of the filter class is optionally followed by a string
43 @var{arguments} is a string which contains the parameters used to
44 initialize the filter instance, and are described in the filter
47 The list of arguments can be quoted using the character "'" as initial
48 and ending mark, and the character '\' for escaping the characters
49 within the quoted text; otherwise the argument string is considered
50 terminated when the next special character (belonging to the set
51 "[]=;,") is encountered.
53 The name and arguments of the filter are optionally preceded and
54 followed by a list of link labels.
55 A link label allows to name a link and associate it to a filter output
56 or input pad. The preceding labels @var{in_link_1}
57 ... @var{in_link_N}, are associated to the filter input pads,
58 the following labels @var{out_link_1} ... @var{out_link_M}, are
59 associated to the output pads.
61 When two link labels with the same name are found in the
62 filtergraph, a link between the corresponding input and output pad is
65 If an output pad is not labelled, it is linked by default to the first
66 unlabelled input pad of the next filter in the filterchain.
67 For example in the filterchain:
69 nullsrc, split[L1], [L2]overlay, nullsink
71 the split filter instance has two output pads, and the overlay filter
72 instance two input pads. The first output pad of split is labelled
73 "L1", the first input pad of overlay is labelled "L2", and the second
74 output pad of split is linked to the second input pad of overlay,
75 which are both unlabelled.
77 In a complete filterchain all the unlabelled filter input and output
78 pads must be connected. A filtergraph is considered valid if all the
79 filter input and output pads of all the filterchains are connected.
81 Libavfilter will automatically insert scale filters where format
82 conversion is required. It is possible to specify swscale flags
83 for those automatically inserted scalers by prepending
84 @code{sws_flags=@var{flags};}
85 to the filtergraph description.
87 Follows a BNF description for the filtergraph syntax:
89 @var{NAME} ::= sequence of alphanumeric characters and '_'
90 @var{LINKLABEL} ::= "[" @var{NAME} "]"
91 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
92 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
93 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
94 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
95 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
98 @c man end FILTERGRAPH DESCRIPTION
100 @chapter Audio Filters
101 @c man begin AUDIO FILTERS
103 When you configure your FFmpeg build, you can disable any of the
104 existing filters using @code{--disable-filters}.
105 The configure output will show the audio filters included in your
108 Below is a description of the currently available audio filters.
112 Convert the input audio format to the specified formats.
114 The filter accepts a string of the form:
115 "@var{sample_format}:@var{channel_layout}".
117 @var{sample_format} specifies the sample format, and can be a string or the
118 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
119 suffix for a planar sample format.
121 @var{channel_layout} specifies the channel layout, and can be a string
122 or the corresponding number value defined in @file{libavutil/audioconvert.h}.
124 The special parameter "auto", signifies that the filter will
125 automatically select the output format depending on the output filter.
127 Some examples follow.
131 Convert input to float, planar, stereo:
137 Convert input to unsigned 8-bit, automatically select out channel layout:
145 Convert the input audio to one of the specified formats. The framework will
146 negotiate the most appropriate format to minimize conversions.
148 The filter accepts three lists of formats, separated by ":", in the form:
149 "@var{sample_formats}:@var{channel_layouts}:@var{packing_formats}".
151 Elements in each list are separated by "," which has to be escaped in the
152 filtergraph specification.
154 The special parameter "all", in place of a list of elements, signifies all
157 Some examples follow:
159 aformat=u8\\,s16:mono:packed
161 aformat=s16:mono\\,stereo:all
166 Merge two audio streams into a single multi-channel stream.
168 This filter does not need any argument.
170 If the channel layouts of the inputs are disjoint, and therefore compatible,
171 the channel layout of the output will be set accordingly and the channels
172 will be reordered as necessary. If the channel layouts of the inputs are not
173 disjoint, the output will have all the channels of the first input then all
174 the channels of the second input, in that order, and the channel layout of
175 the output will be the default value corresponding to the total number of
178 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
179 is FC+BL+BR, then the output will be in 5.1, with the channels in the
180 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
181 first input, b1 is the first channel of the second input).
183 On the other hand, if both input are in stereo, the output channels will be
184 in the default order: a1, a2, b1, b2, and the channel layout will be
185 arbitrarily set to 4.0, which may or may not be the expected value.
187 Both inputs must have the same sample rate, format and packing.
189 If inputs do not have the same duration, the output will stop with the
192 Example: merge two mono files into a stereo stream:
194 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
197 If you need to do multiple merges (for instance multiple mono audio streams in
198 a single video media), you can do:
201 amovie=input.mkv:si=0 [a0];
202 amovie=input.mkv:si=1 [a1];
203 amovie=input.mkv:si=2 [a2];
204 amovie=input.mkv:si=3 [a3];
205 amovie=input.mkv:si=4 [a4];
206 amovie=input.mkv:si=5 [a5];
207 [a0][a1] amerge [x0];
208 [x0][a2] amerge [x1];
209 [x1][a3] amerge [x2];
210 [x2][a4] amerge [x3];
211 [x3][a5] amerge" -c:a pcm_s16le output.mkv
216 Pass the audio source unchanged to the output.
220 Resample the input audio to the specified sample rate.
222 The filter accepts exactly one parameter, the output sample rate. If not
223 specified then the filter will automatically convert between its input
224 and output sample rates.
226 For example, to resample the input audio to 44100Hz:
233 Show a line containing various information for each input audio frame.
234 The input audio is not modified.
236 The shown line contains a sequence of key/value pairs of the form
237 @var{key}:@var{value}.
239 A description of each shown parameter follows:
243 sequential number of the input frame, starting from 0
246 presentation TimeStamp of the input frame, expressed as a number of
247 time base units. The time base unit depends on the filter input pad, and
248 is usually 1/@var{sample_rate}.
251 presentation TimeStamp of the input frame, expressed as a number of
255 position of the frame in the input stream, -1 if this information in
256 unavailable and/or meaningless (for example in case of synthetic audio)
262 channel layout description
265 number of samples (per each channel) contained in the filtered frame
268 sample rate for the audio frame
271 if the packing format is planar, 0 if packed
274 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
277 Adler-32 checksum (printed in hexadecimal) for each input frame plane,
278 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
284 Pass on the input audio to two outputs. Both outputs are identical to
289 [in] asplit[out0], showaudio[out1]
292 will create two separate outputs from the same input, one cropped and
297 Forward two audio streams and control the order the buffers are forwarded.
299 The argument to the filter is an expression deciding which stream should be
300 forwarded next: if the result is negative, the first stream is forwarded; if
301 the result is positive or zero, the second stream is forwarded. It can use
302 the following variables:
306 number of buffers forwarded so far on each stream
308 number of samples forwarded so far on each stream
310 current timestamp of each stream
313 The default value is @code{t1-t2}, which means to always forward the stream
314 that has a smaller timestamp.
316 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
317 input, while avoiding too much of a desynchronization:
319 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
320 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
326 Make audio easier to listen to on headphones.
328 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
329 so that when listened to on headphones the stereo image is moved from
330 inside your head (standard for headphones) to outside and in front of
331 the listener (standard for speakers).
337 Mix channels with specific gain levels. The filter accepts the output
338 channel layout followed by a set of channels definitions.
340 This filter is also designed to remap efficiently the channels of an audio
343 The filter accepts parameters of the form:
344 "@var{l}:@var{outdef}:@var{outdef}:..."
348 output channel layout or number of channels
351 output channel specification, of the form:
352 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
355 output channel to define, either a channel name (FL, FR, etc.) or a channel
356 number (c0, c1, etc.)
359 multiplicative coefficient for the channel, 1 leaving the volume unchanged
362 input channel to use, see out_name for details; it is not possible to mix
363 named and numbered input channels
366 If the `=' in a channel specification is replaced by `<', then the gains for
367 that specification will be renormalized so that the total is 1, thus
368 avoiding clipping noise.
370 @subsection Mixing examples
372 For example, if you want to down-mix from stereo to mono, but with a bigger
373 factor for the left channel:
375 pan=1:c0=0.9*c0+0.1*c1
378 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
381 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
384 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
385 that should be preferred (see "-ac" option) unless you have very specific
388 @subsection Remapping examples
390 The channel remapping will be effective if, and only if:
393 @item gain coefficients are zeroes or ones,
394 @item only one input per channel output,
397 If all these conditions are satisfied, the filter will notify the user ("Pure
398 channel mapping detected"), and use an optimized and lossless method to do the
401 For example, if you have a 5.1 source and want a stereo audio stream by
402 dropping the extra channels:
404 pan="stereo: c0=FL : c1=FR"
407 Given the same source, you can also switch front left and front right channels
408 and keep the input channel layout:
410 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
413 If the input is a stereo audio stream, you can mute the front left channel (and
414 still keep the stereo channel layout) with:
419 Still with a stereo audio stream input, you can copy the right channel in both
420 front left and right:
422 pan="stereo: c0=FR : c1=FR"
425 @section silencedetect
427 Detect silence in an audio stream.
429 This filter logs a message when it detects that the input audio volume is less
430 or equal to a noise tolerance value for a duration greater or equal to the
431 minimum detected noise duration.
433 The printed times and duration are expressed in seconds.
437 Set silence duration until notification (default is 2 seconds).
440 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
441 specified value) or amplitude ratio. Default is -60dB, or 0.001.
444 Detect 5 seconds of silence with -50dB noise tolerance:
446 silencedetect=n=-50dB:d=5
449 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
450 tolerance in @file{silence.mp3}:
452 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
457 Adjust the input audio volume.
459 The filter accepts exactly one parameter @var{vol}, which expresses
460 how the audio volume will be increased or decreased.
462 Output values are clipped to the maximum value.
464 If @var{vol} is expressed as a decimal number, the output audio
465 volume is given by the relation:
467 @var{output_volume} = @var{vol} * @var{input_volume}
470 If @var{vol} is expressed as a decimal number followed by the string
471 "dB", the value represents the requested change in decibels of the
472 input audio power, and the output audio volume is given by the
475 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
478 Otherwise @var{vol} is considered an expression and its evaluated
479 value is used for computing the output audio volume according to the
482 Default value for @var{vol} is 1.0.
488 Half the input audio volume:
493 The above example is equivalent to:
499 Decrease input audio power by 12 decibels:
505 @c man end AUDIO FILTERS
507 @chapter Audio Sources
508 @c man begin AUDIO SOURCES
510 Below is a description of the currently available audio sources.
514 Buffer audio frames, and make them available to the filter chain.
516 This source is mainly intended for a programmatic use, in particular
517 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
519 It accepts the following mandatory parameters:
520 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
525 The sample rate of the incoming audio buffers.
528 The sample format of the incoming audio buffers.
529 Either a sample format name or its corresponging integer representation from
530 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
533 The channel layout of the incoming audio buffers.
534 Either a channel layout name from channel_layout_map in
535 @file{libavutil/audioconvert.c} or its corresponding integer representation
536 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
539 Either "packed" or "planar", or their integer representation: 0 or 1
546 abuffer=44100:s16:stereo:planar
549 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
550 Since the sample format with name "s16" corresponds to the number
551 1 and the "stereo" channel layout corresponds to the value 0x3, this is
554 abuffer=44100:1:0x3:1
559 Generate an audio signal specified by an expression.
561 This source accepts in input one or more expressions (one for each
562 channel), which are evaluated and used to generate a corresponding
565 It accepts the syntax: @var{exprs}[::@var{options}].
566 @var{exprs} is a list of expressions separated by ":", one for each
567 separate channel. The output channel layout depends on the number of
568 provided expressions, up to 8 channels are supported.
570 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
573 The description of the accepted options follows.
578 Set the minimum duration of the sourced audio. See the function
579 @code{av_parse_time()} for the accepted format.
580 Note that the resulting duration may be greater than the specified
581 duration, as the generated audio is always cut at the end of a
584 If not specified, or the expressed duration is negative, the audio is
585 supposed to be generated forever.
588 Set the number of samples per channel per each output frame,
592 Specify the sample rate, default to 44100.
595 Each expression in @var{exprs} can contain the following constants:
599 number of the evaluated sample, starting from 0
602 time of the evaluated sample expressed in seconds, starting from 0
621 Generate a sin signal with frequency of 440 Hz, set sample rate to
624 aevalsrc="sin(440*2*PI*t)::s=8000"
628 Generate white noise:
630 aevalsrc="-2+random(0)"
634 Generate an amplitude modulated signal:
636 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
640 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
642 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
649 Read an audio stream from a movie container.
651 It accepts the syntax: @var{movie_name}[:@var{options}] where
652 @var{movie_name} is the name of the resource to read (not necessarily
653 a file but also a device or a stream accessed through some protocol),
654 and @var{options} is an optional sequence of @var{key}=@var{value}
655 pairs, separated by ":".
657 The description of the accepted options follows.
662 Specify the format assumed for the movie to read, and can be either
663 the name of a container or an input device. If not specified the
664 format is guessed from @var{movie_name} or by probing.
667 Specify the seek point in seconds, the frames will be output
668 starting from this seek point, the parameter is evaluated with
669 @code{av_strtod} so the numerical value may be suffixed by an IS
670 postfix. Default value is "0".
672 @item stream_index, si
673 Specify the index of the audio stream to read. If the value is -1,
674 the best suited audio stream will be automatically selected. Default
681 Null audio source, return unprocessed audio frames. It is mainly useful
682 as a template and to be employed in analysis / debugging tools, or as
683 the source for filters which ignore the input data (for example the sox
686 It accepts an optional sequence of @var{key}=@var{value} pairs,
689 The description of the accepted options follows.
694 Specify the sample rate, and defaults to 44100.
696 @item channel_layout, cl
698 Specify the channel layout, and can be either an integer or a string
699 representing a channel layout. The default value of @var{channel_layout}
702 Check the channel_layout_map definition in
703 @file{libavcodec/audioconvert.c} for the mapping between strings and
704 channel layout values.
707 Set the number of samples per requested frames.
711 Follow some examples:
713 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
714 anullsrc=r=48000:cl=4
717 anullsrc=r=48000:cl=mono
720 @c man end AUDIO SOURCES
723 @c man begin AUDIO SINKS
725 Below is a description of the currently available audio sinks.
729 Buffer audio frames, and make them available to the end of filter chain.
731 This sink is mainly intended for programmatic use, in particular
732 through the interface defined in @file{libavfilter/buffersink.h}.
734 It requires a pointer to an AVABufferSinkContext structure, which
735 defines the incoming buffers' formats, to be passed as the opaque
736 parameter to @code{avfilter_init_filter} for initialization.
740 Null audio sink, do absolutely nothing with the input audio. It is
741 mainly useful as a template and to be employed in analysis / debugging
744 @c man end AUDIO SINKS
746 @chapter Video Filters
747 @c man begin VIDEO FILTERS
749 When you configure your FFmpeg build, you can disable any of the
750 existing filters using @code{--disable-filters}.
751 The configure output will show the video filters included in your
754 Below is a description of the currently available video filters.
758 Draw ASS (Advanced Substation Alpha) subtitles on top of input video
759 using the libass library.
761 To enable compilation of this filter you need to configure FFmpeg with
762 @code{--enable-libass}.
764 This filter accepts the syntax: @var{ass_filename}[:@var{options}],
765 where @var{ass_filename} is the filename of the ASS file to read, and
766 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
769 A description of the accepted options follows.
773 Specifies the size of the original video, the video for which the ASS file
774 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
775 necessary to correctly scale the fonts if the aspect ratio has been changed.
778 For example, to render the file @file{sub.ass} on top of the input
779 video, use the command:
786 Compute the bounding box for the non-black pixels in the input frame
789 This filter computes the bounding box containing all the pixels with a
790 luminance value greater than the minimum allowed value.
791 The parameters describing the bounding box are printed on the filter
796 Detect video intervals that are (almost) completely black. Can be
797 useful to detect chapter transitions, commercials, or invalid
798 recordings. Output lines contains the time for the start, end and
799 duration of the detected black interval expressed in seconds.
801 In order to display the output lines, you need to set the loglevel at
802 least to the AV_LOG_INFO value.
804 This filter accepts a list of options in the form of
805 @var{key}=@var{value} pairs separated by ":". A description of the
806 accepted options follows.
809 @item black_min_duration, d
810 Set the minimum detected black duration expressed in seconds. It must
811 be a non-negative floating point number.
813 Default value is 2.0.
815 @item picture_black_ratio_th, pic_th
816 Set the threshold for considering a picture "black".
817 Express the minimum value for the ratio:
819 @var{nb_black_pixels} / @var{nb_pixels}
822 for which a picture is considered black.
823 Default value is 0.98.
825 @item pixel_black_th, pix_th
826 Set the threshold for considering a pixel "black".
828 The threshold expresses the maximum pixel luminance value for which a
829 pixel is considered "black". The provided value is scaled according to
830 the following equation:
832 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
835 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
836 the input video format, the range is [0-255] for YUV full-range
837 formats and [16-235] for YUV non full-range formats.
839 Default value is 0.10.
842 The following example sets the maximum pixel threshold to the minimum
843 value, and detects only black intervals of 2 or more seconds:
845 blackdetect=d=2:pix_th=0.00
850 Detect frames that are (almost) completely black. Can be useful to
851 detect chapter transitions or commercials. Output lines consist of
852 the frame number of the detected frame, the percentage of blackness,
853 the position in the file if known or -1 and the timestamp in seconds.
855 In order to display the output lines, you need to set the loglevel at
856 least to the AV_LOG_INFO value.
858 The filter accepts the syntax:
860 blackframe[=@var{amount}:[@var{threshold}]]
863 @var{amount} is the percentage of the pixels that have to be below the
864 threshold, and defaults to 98.
866 @var{threshold} is the threshold below which a pixel value is
867 considered black, and defaults to 32.
871 Apply boxblur algorithm to the input video.
873 This filter accepts the parameters:
874 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
876 Chroma and alpha parameters are optional, if not specified they default
877 to the corresponding values set for @var{luma_radius} and
880 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
881 the radius in pixels of the box used for blurring the corresponding
882 input plane. They are expressions, and can contain the following
886 the input width and height in pixels
889 the input chroma image width and height in pixels
892 horizontal and vertical chroma subsample values. For example for the
893 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
896 The radius must be a non-negative number, and must not be greater than
897 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
898 and of @code{min(cw,ch)/2} for the chroma planes.
900 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
901 how many times the boxblur filter is applied to the corresponding
904 Some examples follow:
909 Apply a boxblur filter with luma, chroma, and alpha radius
916 Set luma radius to 2, alpha and chroma radius to 0
922 Set luma and chroma radius to a fraction of the video dimension
924 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
931 The colormatrix filter allows conversion between any of the following color
932 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
935 The syntax of the parameters is @var{source}:@var{destination}:
938 colormatrix=bt601:smpte240m
943 Copy the input source unchanged to the output. Mainly useful for
948 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
950 The @var{keep_aspect} parameter is optional, if specified and set to a
951 non-zero value will force the output display aspect ratio to be the
952 same of the input, by changing the output sample aspect ratio.
954 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
955 expressions containing the following constants:
959 the computed values for @var{x} and @var{y}. They are evaluated for
963 the input width and height
966 same as @var{in_w} and @var{in_h}
969 the output (cropped) width and height
972 same as @var{out_w} and @var{out_h}
975 same as @var{iw} / @var{ih}
978 input sample aspect ratio
981 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
984 horizontal and vertical chroma subsample values. For example for the
985 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
988 the number of input frame, starting from 0
991 the position in the file of the input frame, NAN if unknown
994 timestamp expressed in seconds, NAN if the input timestamp is unknown
998 The @var{out_w} and @var{out_h} parameters specify the expressions for
999 the width and height of the output (cropped) video. They are
1000 evaluated just at the configuration of the filter.
1002 The default value of @var{out_w} is "in_w", and the default value of
1003 @var{out_h} is "in_h".
1005 The expression for @var{out_w} may depend on the value of @var{out_h},
1006 and the expression for @var{out_h} may depend on @var{out_w}, but they
1007 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1008 evaluated after @var{out_w} and @var{out_h}.
1010 The @var{x} and @var{y} parameters specify the expressions for the
1011 position of the top-left corner of the output (non-cropped) area. They
1012 are evaluated for each frame. If the evaluated value is not valid, it
1013 is approximated to the nearest valid value.
1015 The default value of @var{x} is "(in_w-out_w)/2", and the default
1016 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
1017 the center of the input image.
1019 The expression for @var{x} may depend on @var{y}, and the expression
1020 for @var{y} may depend on @var{x}.
1022 Follow some examples:
1024 # crop the central input area with size 100x100
1027 # crop the central input area with size 2/3 of the input video
1028 "crop=2/3*in_w:2/3*in_h"
1030 # crop the input video central square
1033 # delimit the rectangle with the top-left corner placed at position
1034 # 100:100 and the right-bottom corner corresponding to the right-bottom
1035 # corner of the input image.
1036 crop=in_w-100:in_h-100:100:100
1038 # crop 10 pixels from the left and right borders, and 20 pixels from
1039 # the top and bottom borders
1040 "crop=in_w-2*10:in_h-2*20"
1042 # keep only the bottom right quarter of the input image
1043 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1045 # crop height for getting Greek harmony
1046 "crop=in_w:1/PHI*in_w"
1049 "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)"
1051 # erratic camera effect depending on timestamp
1052 "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)"
1054 # set x depending on the value of y
1055 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1060 Auto-detect crop size.
1062 Calculate necessary cropping parameters and prints the recommended
1063 parameters through the logging system. The detected dimensions
1064 correspond to the non-black area of the input video.
1066 It accepts the syntax:
1068 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1074 Threshold, which can be optionally specified from nothing (0) to
1075 everything (255), defaults to 24.
1078 Value which the width/height should be divisible by, defaults to
1079 16. The offset is automatically adjusted to center the video. Use 2 to
1080 get only even dimensions (needed for 4:2:2 video). 16 is best when
1081 encoding to most video codecs.
1084 Counter that determines after how many frames cropdetect will reset
1085 the previously detected largest video area and start over to detect
1086 the current optimal crop area. Defaults to 0.
1088 This can be useful when channel logos distort the video area. 0
1089 indicates never reset and return the largest area encountered during
1095 Suppress a TV station logo by a simple interpolation of the surrounding
1096 pixels. Just set a rectangle covering the logo and watch it disappear
1097 (and sometimes something even uglier appear - your mileage may vary).
1099 The filter accepts parameters as a string of the form
1100 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1101 @var{key}=@var{value} pairs, separated by ":".
1103 The description of the accepted parameters follows.
1108 Specify the top left corner coordinates of the logo. They must be
1112 Specify the width and height of the logo to clear. They must be
1116 Specify the thickness of the fuzzy edge of the rectangle (added to
1117 @var{w} and @var{h}). The default value is 4.
1120 When set to 1, a green rectangle is drawn on the screen to simplify
1121 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1122 @var{band} is set to 4. The default value is 0.
1126 Some examples follow.
1131 Set a rectangle covering the area with top left corner coordinates 0,0
1132 and size 100x77, setting a band of size 10:
1134 delogo=0:0:100:77:10
1138 As the previous example, but use named options:
1140 delogo=x=0:y=0:w=100:h=77:band=10
1147 Attempt to fix small changes in horizontal and/or vertical shift. This
1148 filter helps remove camera shake from hand-holding a camera, bumping a
1149 tripod, moving on a vehicle, etc.
1151 The filter accepts parameters as a string of the form
1152 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1154 A description of the accepted parameters follows.
1159 Specify a rectangular area where to limit the search for motion
1161 If desired the search for motion vectors can be limited to a
1162 rectangular area of the frame defined by its top left corner, width
1163 and height. These parameters have the same meaning as the drawbox
1164 filter which can be used to visualise the position of the bounding
1167 This is useful when simultaneous movement of subjects within the frame
1168 might be confused for camera motion by the motion vector search.
1170 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1171 then the full frame is used. This allows later options to be set
1172 without specifying the bounding box for the motion vector search.
1174 Default - search the whole frame.
1177 Specify the maximum extent of movement in x and y directions in the
1178 range 0-64 pixels. Default 16.
1181 Specify how to generate pixels to fill blanks at the edge of the
1182 frame. An integer from 0 to 3 as follows:
1185 Fill zeroes at blank locations
1187 Original image at blank locations
1189 Extruded edge value at blank locations
1191 Mirrored edge at blank locations
1194 The default setting is mirror edge at blank locations.
1197 Specify the blocksize to use for motion search. Range 4-128 pixels,
1201 Specify the contrast threshold for blocks. Only blocks with more than
1202 the specified contrast (difference between darkest and lightest
1203 pixels) will be considered. Range 1-255, default 125.
1206 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1207 search. Default - exhaustive search.
1210 If set then a detailed log of the motion search is written to the
1217 Draw a colored box on the input image.
1219 It accepts the syntax:
1221 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
1227 Specify the top left corner coordinates of the box. Default to 0.
1230 Specify the width and height of the box, if 0 they are interpreted as
1231 the input width and height. Default to 0.
1234 Specify the color of the box to write, it can be the name of a color
1235 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1238 Follow some examples:
1240 # draw a black box around the edge of the input image
1243 # draw a box with color red and an opacity of 50%
1244 drawbox=10:20:200:60:red@@0.5"
1249 Draw text string or text from specified file on top of video using the
1250 libfreetype library.
1252 To enable compilation of this filter you need to configure FFmpeg with
1253 @code{--enable-libfreetype}.
1255 The filter also recognizes strftime() sequences in the provided text
1256 and expands them accordingly. Check the documentation of strftime().
1258 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1261 The description of the accepted parameters follows.
1266 The font file to be used for drawing text. Path must be included.
1267 This parameter is mandatory.
1270 The text string to be drawn. The text must be a sequence of UTF-8
1272 This parameter is mandatory if no file is specified with the parameter
1276 A text file containing text to be drawn. The text must be a sequence
1277 of UTF-8 encoded characters.
1279 This parameter is mandatory if no text string is specified with the
1280 parameter @var{text}.
1282 If both text and textfile are specified, an error is thrown.
1285 The expressions which specify the offsets where text will be drawn
1286 within the video frame. They are relative to the top/left border of the
1289 The default value of @var{x} and @var{y} is "0".
1291 See below for the list of accepted constants.
1294 The font size to be used for drawing text.
1295 The default value of @var{fontsize} is 16.
1298 The color to be used for drawing fonts.
1299 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1300 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1301 The default value of @var{fontcolor} is "black".
1304 The color to be used for drawing box around text.
1305 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1306 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1307 The default value of @var{boxcolor} is "white".
1310 Used to draw a box around text using background color.
1311 Value should be either 1 (enable) or 0 (disable).
1312 The default value of @var{box} is 0.
1314 @item shadowx, shadowy
1315 The x and y offsets for the text shadow position with respect to the
1316 position of the text. They can be either positive or negative
1317 values. Default value for both is "0".
1320 The color to be used for drawing a shadow behind the drawn text. It
1321 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1322 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1323 The default value of @var{shadowcolor} is "black".
1326 Flags to be used for loading the fonts.
1328 The flags map the corresponding flags supported by libfreetype, and are
1329 a combination of the following values:
1336 @item vertical_layout
1337 @item force_autohint
1340 @item ignore_global_advance_width
1342 @item ignore_transform
1349 Default value is "render".
1351 For more information consult the documentation for the FT_LOAD_*
1355 The size in number of spaces to use for rendering the tab.
1359 If true, check and fix text coords to avoid clipping.
1362 The parameters for @var{x} and @var{y} are expressions containing the
1363 following constants:
1367 the input width and height
1370 the width of the rendered text
1373 the height of the rendered text
1376 the height of each text line
1379 input sample aspect ratio
1382 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1385 horizontal and vertical chroma subsample values. For example for the
1386 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1389 maximum glyph width, that is the maximum width for all the glyphs
1390 contained in the rendered text
1393 maximum glyph height, that is the maximum height for all the glyphs
1394 contained in the rendered text, it is equivalent to @var{ascent} -
1397 @item max_glyph_a, ascent
1399 the maximum distance from the baseline to the highest/upper grid
1400 coordinate used to place a glyph outline point, for all the rendered
1402 It is a positive value, due to the grid's orientation with the Y axis
1405 @item max_glyph_d, descent
1406 the maximum distance from the baseline to the lowest grid coordinate
1407 used to place a glyph outline point, for all the rendered glyphs.
1408 This is a negative value, due to the grid's orientation, with the Y axis
1412 the number of input frame, starting from 0
1415 timestamp expressed in seconds, NAN if the input timestamp is unknown
1418 initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
1419 with or without text parameter. @var{rate} option must be specified.
1422 frame rate (timecode only)
1425 If libavfilter was built with @code{--enable-fontconfig}, then
1426 @option{fontfile} can be a fontconfig pattern or omitted.
1428 Some examples follow.
1433 Draw "Test Text" with font FreeSerif, using the default values for the
1434 optional parameters.
1437 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1441 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1442 and y=50 (counting from the top-left corner of the screen), text is
1443 yellow with a red box around it. Both the text and the box have an
1447 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1448 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1451 Note that the double quotes are not necessary if spaces are not used
1452 within the parameter list.
1455 Show the text at the center of the video frame:
1457 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1461 Show a text line sliding from right to left in the last row of the video
1462 frame. The file @file{LONG_LINE} is assumed to contain a single line
1465 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1469 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1471 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1475 Draw a single green letter "g", at the center of the input video.
1476 The glyph baseline is placed at half screen height.
1478 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1482 Use fontconfig to set the font. Note that the colons need to be escaped.
1484 drawtext='fontfile=Linux Libertine O-40\\:style=Semibold:text=FFmpeg'
1489 For more information about libfreetype, check:
1490 @url{http://www.freetype.org/}.
1492 For more information about fontconfig, check:
1493 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
1497 Apply fade-in/out effect to input video.
1499 It accepts the parameters:
1500 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1502 @var{type} specifies if the effect type, can be either "in" for
1503 fade-in, or "out" for a fade-out effect.
1505 @var{start_frame} specifies the number of the start frame for starting
1506 to apply the fade effect.
1508 @var{nb_frames} specifies the number of frames for which the fade
1509 effect has to last. At the end of the fade-in effect the output video
1510 will have the same intensity as the input video, at the end of the
1511 fade-out transition the output video will be completely black.
1513 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1514 separated by ":". The description of the accepted options follows.
1521 @item start_frame, s
1522 See @var{start_frame}.
1525 See @var{nb_frames}.
1528 If set to 1, fade only alpha channel, if one exists on the input.
1532 A few usage examples follow, usable too as test scenarios.
1534 # fade in first 30 frames of video
1537 # fade out last 45 frames of a 200-frame video
1540 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1541 fade=in:0:25, fade=out:975:25
1543 # make first 5 frames black, then fade in from frame 5-24
1546 # fade in alpha over first 25 frames of video
1547 fade=in:0:25:alpha=1
1552 Transform the field order of the input video.
1554 It accepts one parameter which specifies the required field order that
1555 the input interlaced video will be transformed to. The parameter can
1556 assume one of the following values:
1560 output bottom field first
1562 output top field first
1565 Default value is "tff".
1567 Transformation is achieved by shifting the picture content up or down
1568 by one line, and filling the remaining line with appropriate picture content.
1569 This method is consistent with most broadcast field order converters.
1571 If the input video is not flagged as being interlaced, or it is already
1572 flagged as being of the required output field order then this filter does
1573 not alter the incoming video.
1575 This filter is very useful when converting to or from PAL DV material,
1576 which is bottom field first.
1580 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1585 Buffer input images and send them when they are requested.
1587 This filter is mainly useful when auto-inserted by the libavfilter
1590 The filter does not take parameters.
1594 Convert the input video to one of the specified pixel formats.
1595 Libavfilter will try to pick one that is supported for the input to
1598 The filter accepts a list of pixel format names, separated by ":",
1599 for example "yuv420p:monow:rgb24".
1601 Some examples follow:
1603 # convert the input video to the format "yuv420p"
1606 # convert the input video to any of the formats in the list
1607 format=yuv420p:yuv444p:yuv410p
1613 Apply a frei0r effect to the input video.
1615 To enable compilation of this filter you need to install the frei0r
1616 header and configure FFmpeg with @code{--enable-frei0r}.
1618 The filter supports the syntax:
1620 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1623 @var{filter_name} is the name to the frei0r effect to load. If the
1624 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1625 is searched in each one of the directories specified by the colon
1626 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1627 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1628 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1630 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1631 for the frei0r effect.
1633 A frei0r effect parameter can be a boolean (whose values are specified
1634 with "y" and "n"), a double, a color (specified by the syntax
1635 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1636 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1637 description), a position (specified by the syntax @var{X}/@var{Y},
1638 @var{X} and @var{Y} being float numbers) and a string.
1640 The number and kind of parameters depend on the loaded effect. If an
1641 effect parameter is not specified the default value is set.
1643 Some examples follow:
1645 # apply the distort0r effect, set the first two double parameters
1646 frei0r=distort0r:0.5:0.01
1648 # apply the colordistance effect, takes a color as first parameter
1649 frei0r=colordistance:0.2/0.3/0.4
1650 frei0r=colordistance:violet
1651 frei0r=colordistance:0x112233
1653 # apply the perspective effect, specify the top left and top right
1655 frei0r=perspective:0.2/0.2:0.8/0.2
1658 For more information see:
1659 @url{http://piksel.org/frei0r}
1663 Fix the banding artifacts that are sometimes introduced into nearly flat
1664 regions by truncation to 8bit color depth.
1665 Interpolate the gradients that should go where the bands are, and
1668 This filter is designed for playback only. Do not use it prior to
1669 lossy compression, because compression tends to lose the dither and
1670 bring back the bands.
1672 The filter takes two optional parameters, separated by ':':
1673 @var{strength}:@var{radius}
1675 @var{strength} is the maximum amount by which the filter will change
1676 any one pixel. Also the threshold for detecting nearly flat
1677 regions. Acceptable values range from .51 to 255, default value is
1678 1.2, out-of-range values will be clipped to the valid range.
1680 @var{radius} is the neighborhood to fit the gradient to. A larger
1681 radius makes for smoother gradients, but also prevents the filter from
1682 modifying the pixels near detailed regions. Acceptable values are
1683 8-32, default value is 16, out-of-range values will be clipped to the
1687 # default parameters
1696 Flip the input video horizontally.
1698 For example to horizontally flip the input video with @command{ffmpeg}:
1700 ffmpeg -i in.avi -vf "hflip" out.avi
1705 High precision/quality 3d denoise filter. This filter aims to reduce
1706 image noise producing smooth images and making still images really
1707 still. It should enhance compressibility.
1709 It accepts the following optional parameters:
1710 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1714 a non-negative float number which specifies spatial luma strength,
1717 @item chroma_spatial
1718 a non-negative float number which specifies spatial chroma strength,
1719 defaults to 3.0*@var{luma_spatial}/4.0
1722 a float number which specifies luma temporal strength, defaults to
1723 6.0*@var{luma_spatial}/4.0
1726 a float number which specifies chroma temporal strength, defaults to
1727 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1732 Interlaceing detect filter. This filter tries to detect if the input is
1733 interlaced or progressive. Top or bottom field first.
1735 @section lut, lutrgb, lutyuv
1737 Compute a look-up table for binding each pixel component input value
1738 to an output value, and apply it to input video.
1740 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1741 to an RGB input video.
1743 These filters accept in input a ":"-separated list of options, which
1744 specify the expressions used for computing the lookup table for the
1745 corresponding pixel component values.
1747 The @var{lut} filter requires either YUV or RGB pixel formats in
1748 input, and accepts the options:
1751 first pixel component
1753 second pixel component
1755 third pixel component
1757 fourth pixel component, corresponds to the alpha component
1760 The exact component associated to each option depends on the format in
1763 The @var{lutrgb} filter requires RGB pixel formats in input, and
1764 accepts the options:
1776 The @var{lutyuv} filter requires YUV pixel formats in input, and
1777 accepts the options:
1780 Y/luminance component
1789 The expressions can contain the following constants and functions:
1793 the input width and height
1796 input value for the pixel component
1799 the input value clipped in the @var{minval}-@var{maxval} range
1802 maximum value for the pixel component
1805 minimum value for the pixel component
1808 the negated value for the pixel component value clipped in the
1809 @var{minval}-@var{maxval} range , it corresponds to the expression
1810 "maxval-clipval+minval"
1813 the computed value in @var{val} clipped in the
1814 @var{minval}-@var{maxval} range
1816 @item gammaval(gamma)
1817 the computed gamma correction value of the pixel component value
1818 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1820 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1824 All expressions default to "val".
1826 Some examples follow:
1828 # negate input video
1829 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1830 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1832 # the above is the same as
1833 lutrgb="r=negval:g=negval:b=negval"
1834 lutyuv="y=negval:u=negval:v=negval"
1839 # remove chroma components, turns the video into a graytone image
1840 lutyuv="u=128:v=128"
1842 # apply a luma burning effect
1845 # remove green and blue components
1848 # set a constant alpha channel value on input
1849 format=rgba,lutrgb=a="maxval-minval/2"
1851 # correct luminance gamma by a 0.5 factor
1852 lutyuv=y=gammaval(0.5)
1857 Apply an MPlayer filter to the input video.
1859 This filter provides a wrapper around most of the filters of
1862 This wrapper is considered experimental. Some of the wrapped filters
1863 may not work properly and we may drop support for them, as they will
1864 be implemented natively into FFmpeg. Thus you should avoid
1865 depending on them when writing portable scripts.
1867 The filters accepts the parameters:
1868 @var{filter_name}[:=]@var{filter_params}
1870 @var{filter_name} is the name of a supported MPlayer filter,
1871 @var{filter_params} is a string containing the parameters accepted by
1874 The list of the currently supported filters follows:
1924 The parameter syntax and behavior for the listed filters are the same
1925 of the corresponding MPlayer filters. For detailed instructions check
1926 the "VIDEO FILTERS" section in the MPlayer manual.
1928 Some examples follow:
1930 # adjust gamma, brightness, contrast
1933 # tweak hue and saturation
1937 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1943 This filter accepts an integer in input, if non-zero it negates the
1944 alpha component (if available). The default value in input is 0.
1948 Force libavfilter not to use any of the specified pixel formats for the
1949 input to the next filter.
1951 The filter accepts a list of pixel format names, separated by ":",
1952 for example "yuv420p:monow:rgb24".
1954 Some examples follow:
1956 # force libavfilter to use a format different from "yuv420p" for the
1957 # input to the vflip filter
1958 noformat=yuv420p,vflip
1960 # convert the input video to any of the formats not contained in the list
1961 noformat=yuv420p:yuv444p:yuv410p
1966 Pass the video source unchanged to the output.
1970 Apply video transform using libopencv.
1972 To enable this filter install libopencv library and headers and
1973 configure FFmpeg with @code{--enable-libopencv}.
1975 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1977 @var{filter_name} is the name of the libopencv filter to apply.
1979 @var{filter_params} specifies the parameters to pass to the libopencv
1980 filter. If not specified the default values are assumed.
1982 Refer to the official libopencv documentation for more precise
1984 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1986 Follows the list of supported libopencv filters.
1991 Dilate an image by using a specific structuring element.
1992 This filter corresponds to the libopencv function @code{cvDilate}.
1994 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1996 @var{struct_el} represents a structuring element, and has the syntax:
1997 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1999 @var{cols} and @var{rows} represent the number of columns and rows of
2000 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
2001 point, and @var{shape} the shape for the structuring element, and
2002 can be one of the values "rect", "cross", "ellipse", "custom".
2004 If the value for @var{shape} is "custom", it must be followed by a
2005 string of the form "=@var{filename}". The file with name
2006 @var{filename} is assumed to represent a binary image, with each
2007 printable character corresponding to a bright pixel. When a custom
2008 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
2009 or columns and rows of the read file are assumed instead.
2011 The default value for @var{struct_el} is "3x3+0x0/rect".
2013 @var{nb_iterations} specifies the number of times the transform is
2014 applied to the image, and defaults to 1.
2016 Follow some example:
2018 # use the default values
2021 # dilate using a structuring element with a 5x5 cross, iterate two times
2022 ocv=dilate=5x5+2x2/cross:2
2024 # read the shape from the file diamond.shape, iterate two times
2025 # the file diamond.shape may contain a pattern of characters like this:
2031 # the specified cols and rows are ignored (but not the anchor point coordinates)
2032 ocv=0x0+2x2/custom=diamond.shape:2
2037 Erode an image by using a specific structuring element.
2038 This filter corresponds to the libopencv function @code{cvErode}.
2040 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
2041 with the same syntax and semantics as the @ref{dilate} filter.
2045 Smooth the input video.
2047 The filter takes the following parameters:
2048 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
2050 @var{type} is the type of smooth filter to apply, and can be one of
2051 the following values: "blur", "blur_no_scale", "median", "gaussian",
2052 "bilateral". The default value is "gaussian".
2054 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
2055 parameters whose meanings depend on smooth type. @var{param1} and
2056 @var{param2} accept integer positive values or 0, @var{param3} and
2057 @var{param4} accept float values.
2059 The default value for @var{param1} is 3, the default value for the
2060 other parameters is 0.
2062 These parameters correspond to the parameters assigned to the
2063 libopencv function @code{cvSmooth}.
2068 Overlay one video on top of another.
2070 It takes two inputs and one output, the first input is the "main"
2071 video on which the second input is overlayed.
2073 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
2075 @var{x} is the x coordinate of the overlayed video on the main video,
2076 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
2077 the following parameters:
2080 @item main_w, main_h
2081 main input width and height
2084 same as @var{main_w} and @var{main_h}
2086 @item overlay_w, overlay_h
2087 overlay input width and height
2090 same as @var{overlay_w} and @var{overlay_h}
2093 @var{options} is an optional list of @var{key}=@var{value} pairs,
2096 The description of the accepted options follows.
2100 If set to 1, force the filter to accept inputs in the RGB
2101 color space. Default value is 0.
2104 Be aware that frames are taken from each input video in timestamp
2105 order, hence, if their initial timestamps differ, it is a a good idea
2106 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
2107 have them begin in the same zero timestamp, as it does the example for
2108 the @var{movie} filter.
2110 Follow some examples:
2112 # draw the overlay at 10 pixels from the bottom right
2113 # corner of the main video.
2114 overlay=main_w-overlay_w-10:main_h-overlay_h-10
2116 # insert a transparent PNG logo in the bottom left corner of the input
2117 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
2119 # insert 2 different transparent PNG logos (second logo on bottom
2121 ffmpeg -i input -i logo1 -i logo2 -filter_complex
2122 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
2124 # add a transparent color layer on top of the main video,
2125 # WxH specifies the size of the main input to the overlay filter
2126 color=red@.3:WxH [over]; [in][over] overlay [out]
2129 You can chain together more overlays but the efficiency of such
2130 approach is yet to be tested.
2134 Add paddings to the input image, and places the original input at the
2135 given coordinates @var{x}, @var{y}.
2137 It accepts the following parameters:
2138 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
2140 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
2141 expressions containing the following constants:
2145 the input video width and height
2148 same as @var{in_w} and @var{in_h}
2151 the output width and height, that is the size of the padded area as
2152 specified by the @var{width} and @var{height} expressions
2155 same as @var{out_w} and @var{out_h}
2158 x and y offsets as specified by the @var{x} and @var{y}
2159 expressions, or NAN if not yet specified
2162 same as @var{iw} / @var{ih}
2165 input sample aspect ratio
2168 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2171 horizontal and vertical chroma subsample values. For example for the
2172 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2175 Follows the description of the accepted parameters.
2180 Specify the size of the output image with the paddings added. If the
2181 value for @var{width} or @var{height} is 0, the corresponding input size
2182 is used for the output.
2184 The @var{width} expression can reference the value set by the
2185 @var{height} expression, and vice versa.
2187 The default value of @var{width} and @var{height} is 0.
2191 Specify the offsets where to place the input image in the padded area
2192 with respect to the top/left border of the output image.
2194 The @var{x} expression can reference the value set by the @var{y}
2195 expression, and vice versa.
2197 The default value of @var{x} and @var{y} is 0.
2201 Specify the color of the padded area, it can be the name of a color
2202 (case insensitive match) or a 0xRRGGBB[AA] sequence.
2204 The default value of @var{color} is "black".
2208 Some examples follow:
2211 # Add paddings with color "violet" to the input video. Output video
2212 # size is 640x480, the top-left corner of the input video is placed at
2214 pad=640:480:0:40:violet
2216 # pad the input to get an output with dimensions increased bt 3/2,
2217 # and put the input video at the center of the padded area
2218 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2220 # pad the input to get a squared output with size equal to the maximum
2221 # value between the input width and height, and put the input video at
2222 # the center of the padded area
2223 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2225 # pad the input to get a final w/h ratio of 16:9
2226 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2228 # for anamorphic video, in order to set the output display aspect ratio,
2229 # it is necessary to use sar in the expression, according to the relation:
2230 # (ih * X / ih) * sar = output_dar
2231 # X = output_dar / sar
2232 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
2234 # double output size and put the input video in the bottom-right
2235 # corner of the output padded area
2236 pad="2*iw:2*ih:ow-iw:oh-ih"
2239 @section pixdesctest
2241 Pixel format descriptor test filter, mainly useful for internal
2242 testing. The output video should be equal to the input video.
2246 format=monow, pixdesctest
2249 can be used to test the monowhite pixel format descriptor definition.
2253 Suppress a TV station logo, using an image file to determine which
2254 pixels comprise the logo. It works by filling in the pixels that
2255 comprise the logo with neighboring pixels.
2257 This filter requires one argument which specifies the filter bitmap
2258 file, which can be any image format supported by libavformat. The
2259 width and height of the image file must match those of the video
2260 stream being processed.
2262 Pixels in the provided bitmap image with a value of zero are not
2263 considered part of the logo, non-zero pixels are considered part of
2264 the logo. If you use white (255) for the logo and black (0) for the
2265 rest, you will be safe. For making the filter bitmap, it is
2266 recommended to take a screen capture of a black frame with the logo
2267 visible, and then using a threshold filter followed by the erode
2268 filter once or twice.
2270 If needed, little splotches can be fixed manually. Remember that if
2271 logo pixels are not covered, the filter quality will be much
2272 reduced. Marking too many pixels as part of the logo does not hurt as
2273 much, but it will increase the amount of blurring needed to cover over
2274 the image and will destroy more information than necessary, and extra
2275 pixels will slow things down on a large logo.
2279 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
2281 The scale filter forces the output display aspect ratio to be the same
2282 of the input, by changing the output sample aspect ratio.
2284 The parameters @var{width} and @var{height} are expressions containing
2285 the following constants:
2289 the input width and height
2292 same as @var{in_w} and @var{in_h}
2295 the output (cropped) width and height
2298 same as @var{out_w} and @var{out_h}
2301 same as @var{iw} / @var{ih}
2304 input sample aspect ratio
2307 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2310 horizontal and vertical chroma subsample values. For example for the
2311 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2314 If the input image format is different from the format requested by
2315 the next filter, the scale filter will convert the input to the
2318 If the value for @var{width} or @var{height} is 0, the respective input
2319 size is used for the output.
2321 If the value for @var{width} or @var{height} is -1, the scale filter will
2322 use, for the respective output size, a value that maintains the aspect
2323 ratio of the input image.
2325 The default value of @var{width} and @var{height} is 0.
2327 Valid values for the optional parameter @var{interl} are:
2331 force interlaced aware scaling
2334 select interlaced aware scaling depending on whether the source frames
2335 are flagged as interlaced or not
2338 Unless @var{interl} is set to one of the above options, interlaced scaling will not be used.
2340 Some examples follow:
2342 # scale the input video to a size of 200x100.
2345 # scale the input to 2x
2347 # the above is the same as
2350 # scale the input to 2x with forced interlaced scaling
2351 scale=2*iw:2*ih:interl=1
2353 # scale the input to half size
2356 # increase the width, and set the height to the same size
2359 # seek for Greek harmony
2363 # increase the height, and set the width to 3/2 of the height
2366 # increase the size, but make the size a multiple of the chroma
2367 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2369 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2370 scale='min(500\, iw*3/2):-1'
2374 Select frames to pass in output.
2376 It accepts in input an expression, which is evaluated for each input
2377 frame. If the expression is evaluated to a non-zero value, the frame
2378 is selected and passed to the output, otherwise it is discarded.
2380 The expression can contain the following constants:
2384 the sequential number of the filtered frame, starting from 0
2387 the sequential number of the selected frame, starting from 0
2389 @item prev_selected_n
2390 the sequential number of the last selected frame, NAN if undefined
2393 timebase of the input timestamps
2396 the PTS (Presentation TimeStamp) of the filtered video frame,
2397 expressed in @var{TB} units, NAN if undefined
2400 the PTS (Presentation TimeStamp) of the filtered video frame,
2401 expressed in seconds, NAN if undefined
2404 the PTS of the previously filtered video frame, NAN if undefined
2406 @item prev_selected_pts
2407 the PTS of the last previously filtered video frame, NAN if undefined
2409 @item prev_selected_t
2410 the PTS of the last previously selected video frame, NAN if undefined
2413 the PTS of the first video frame in the video, NAN if undefined
2416 the time of the first video frame in the video, NAN if undefined
2419 the type of the filtered frame, can assume one of the following
2431 @item interlace_type
2432 the frame interlace type, can assume one of the following values:
2435 the frame is progressive (not interlaced)
2437 the frame is top-field-first
2439 the frame is bottom-field-first
2443 1 if the filtered frame is a key-frame, 0 otherwise
2446 the position in the file of the filtered frame, -1 if the information
2447 is not available (e.g. for synthetic video)
2450 The default value of the select expression is "1".
2452 Some examples follow:
2455 # select all frames in input
2458 # the above is the same as:
2464 # select only I-frames
2465 select='eq(pict_type\,I)'
2467 # select one frame every 100
2468 select='not(mod(n\,100))'
2470 # select only frames contained in the 10-20 time interval
2471 select='gte(t\,10)*lte(t\,20)'
2473 # select only I frames contained in the 10-20 time interval
2474 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2476 # select frames with a minimum distance of 10 seconds
2477 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2480 @section setdar, setsar
2482 The @code{setdar} filter sets the Display Aspect Ratio for the filter
2485 This is done by changing the specified Sample (aka Pixel) Aspect
2486 Ratio, according to the following equation:
2488 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
2491 Keep in mind that the @code{setdar} filter does not modify the pixel
2492 dimensions of the video frame. Also the display aspect ratio set by
2493 this filter may be changed by later filters in the filterchain,
2494 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
2497 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
2498 the filter output video.
2500 Note that as a consequence of the application of this filter, the
2501 output display aspect ratio will change according to the equation
2504 Keep in mind that the sample aspect ratio set by the @code{setsar}
2505 filter may be changed by later filters in the filterchain, e.g. if
2506 another "setsar" or a "setdar" filter is applied.
2508 The @code{setdar} and @code{setsar} filters accept a parameter string
2509 which represents the wanted aspect ratio. The parameter can
2510 be a floating point number string, an expression, or a string of the form
2511 @var{num}:@var{den}, where @var{num} and @var{den} are the numerator
2512 and denominator of the aspect ratio. If the parameter is not
2513 specified, it is assumed the value "0:1".
2515 For example to change the display aspect ratio to 16:9, specify:
2520 The example above is equivalent to:
2525 To change the sample aspect ratio to 10:11, specify:
2532 Force field for the output video frame.
2534 The @code{setfield} filter marks the interlace type field for the
2535 output frames. It does not change the input frame, but only sets the
2536 corresponding property, which affects how the frame is treated by
2537 following filters (e.g. @code{fieldorder} or @code{yadif}).
2539 It accepts a string parameter, which can assume the following values:
2542 Keep the same field property.
2545 Mark the frame as bottom-field-first.
2548 Mark the frame as top-field-first.
2551 Mark the frame as progressive.
2556 Change the PTS (presentation timestamp) of the input video frames.
2558 Accept in input an expression evaluated through the eval API, which
2559 can contain the following constants:
2563 the presentation timestamp in input
2566 the count of the input frame, starting from 0.
2569 the PTS of the first video frame
2572 tell if the current frame is interlaced
2575 original position in the file of the frame, or undefined if undefined
2576 for the current frame
2586 Some examples follow:
2589 # start counting PTS from zero
2601 # fixed rate 25 fps with some jitter
2602 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2607 Set the timebase to use for the output frames timestamps.
2608 It is mainly useful for testing timebase configuration.
2610 It accepts in input an arithmetic expression representing a rational.
2611 The expression can contain the constants "AVTB" (the
2612 default timebase), and "intb" (the input timebase).
2614 The default value for the input is "intb".
2616 Follow some examples.
2619 # set the timebase to 1/25
2622 # set the timebase to 1/10
2625 #set the timebase to 1001/1000
2628 #set the timebase to 2*intb
2631 #set the default timebase value
2637 Show a line containing various information for each input video frame.
2638 The input video is not modified.
2640 The shown line contains a sequence of key/value pairs of the form
2641 @var{key}:@var{value}.
2643 A description of each shown parameter follows:
2647 sequential number of the input frame, starting from 0
2650 Presentation TimeStamp of the input frame, expressed as a number of
2651 time base units. The time base unit depends on the filter input pad.
2654 Presentation TimeStamp of the input frame, expressed as a number of
2658 position of the frame in the input stream, -1 if this information in
2659 unavailable and/or meaningless (for example in case of synthetic video)
2665 sample aspect ratio of the input frame, expressed in the form
2669 size of the input frame, expressed in the form
2670 @var{width}x@var{height}
2673 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2674 for bottom field first)
2677 1 if the frame is a key frame, 0 otherwise
2680 picture type of the input frame ("I" for an I-frame, "P" for a
2681 P-frame, "B" for a B-frame, "?" for unknown type).
2682 Check also the documentation of the @code{AVPictureType} enum and of
2683 the @code{av_get_picture_type_char} function defined in
2684 @file{libavutil/avutil.h}.
2687 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2689 @item plane_checksum
2690 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2691 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2696 Pass the images of input video on to next video filter as multiple
2700 ffmpeg -i in.avi -vf "slicify=32" out.avi
2703 The filter accepts the slice height as parameter. If the parameter is
2704 not specified it will use the default value of 16.
2706 Adding this in the beginning of filter chains should make filtering
2707 faster due to better use of the memory cache.
2711 Pass on the input video to two outputs. Both outputs are identical to
2716 [in] split [splitout1][splitout2];
2717 [splitout1] crop=100:100:0:0 [cropout];
2718 [splitout2] pad=200:200:100:100 [padout];
2721 will create two separate outputs from the same input, one cropped and
2726 Scale the input by 2x and smooth using the Super2xSaI (Scale and
2727 Interpolate) pixel art scaling algorithm.
2729 Useful for enlarging pixel art images without reducing sharpness.
2735 Select the most representative frame in a given sequence of consecutive frames.
2737 It accepts as argument the frames batch size to analyze (default @var{N}=100);
2738 in a set of @var{N} frames, the filter will pick one of them, and then handle
2739 the next batch of @var{N} frames until the end.
2741 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
2742 value will result in a higher memory usage, so a high value is not recommended.
2744 The following example extract one picture each 50 frames:
2749 Complete example of a thumbnail creation with @command{ffmpeg}:
2751 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
2756 Tile several successive frames together.
2758 It accepts as argument the tile size (i.e. the number of lines and columns)
2759 in the form "@var{w}x@var{h}".
2761 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
2764 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
2766 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
2767 duplicating each output frame to accomodate the originally detected frame
2772 Perform various types of temporal field interlacing.
2774 Frames are counted starting from 1, so the first input frame is
2777 This filter accepts a single parameter specifying the mode. Available
2782 Move odd frames into the upper field, even into the lower field,
2783 generating a double height frame at half framerate.
2786 Only output even frames, odd frames are dropped, generating a frame with
2787 unchanged height at half framerate.
2790 Only output odd frames, even frames are dropped, generating a frame with
2791 unchanged height at half framerate.
2794 Expand each frame to full height, but pad alternate lines with black,
2795 generating a frame with double height at the same input framerate.
2798 Interleave the upper field from odd frames with the lower field from
2799 even frames, generating a frame with unchanged height at half framerate.
2802 Interleave the lower field from odd frames with the upper field from
2803 even frames, generating a frame with unchanged height at half framerate.
2810 Transpose rows with columns in the input video and optionally flip it.
2812 It accepts a parameter representing an integer, which can assume the
2817 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2825 Rotate by 90 degrees clockwise, that is:
2833 Rotate by 90 degrees counterclockwise, that is:
2841 Rotate by 90 degrees clockwise and vertically flip, that is:
2851 Sharpen or blur the input video.
2853 It accepts the following parameters:
2854 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2856 Negative values for the amount will blur the input video, while positive
2857 values will sharpen. All parameters are optional and default to the
2858 equivalent of the string '5:5:1.0:5:5:0.0'.
2863 Set the luma matrix horizontal size. It can be an integer between 3
2864 and 13, default value is 5.
2867 Set the luma matrix vertical size. It can be an integer between 3
2868 and 13, default value is 5.
2871 Set the luma effect strength. It can be a float number between -2.0
2872 and 5.0, default value is 1.0.
2874 @item chroma_msize_x
2875 Set the chroma matrix horizontal size. It can be an integer between 3
2876 and 13, default value is 5.
2878 @item chroma_msize_y
2879 Set the chroma matrix vertical size. It can be an integer between 3
2880 and 13, default value is 5.
2883 Set the chroma effect strength. It can be a float number between -2.0
2884 and 5.0, default value is 0.0.
2889 # Strong luma sharpen effect parameters
2892 # Strong blur of both luma and chroma parameters
2893 unsharp=7:7:-2:7:7:-2
2895 # Use the default values with @command{ffmpeg}
2896 ffmpeg -i in.avi -vf "unsharp" out.mp4
2901 Flip the input video vertically.
2904 ffmpeg -i in.avi -vf "vflip" out.avi
2909 Deinterlace the input video ("yadif" means "yet another deinterlacing
2912 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2914 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2919 output 1 frame for each frame
2921 output 1 frame for each field
2923 like 0 but skips spatial interlacing check
2925 like 1 but skips spatial interlacing check
2930 @var{parity} specifies the picture field parity assumed for the input
2931 interlaced video, accepts one of the following values:
2935 assume top field first
2937 assume bottom field first
2939 enable automatic detection
2942 Default value is -1.
2943 If interlacing is unknown or decoder does not export this information,
2944 top field first will be assumed.
2946 @var{auto} specifies if deinterlacer should trust the interlaced flag
2947 and only deinterlace frames marked as interlaced
2951 deinterlace all frames
2953 only deinterlace frames marked as interlaced
2958 @c man end VIDEO FILTERS
2960 @chapter Video Sources
2961 @c man begin VIDEO SOURCES
2963 Below is a description of the currently available video sources.
2967 Buffer video frames, and make them available to the filter chain.
2969 This source is mainly intended for a programmatic use, in particular
2970 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2972 It accepts the following parameters:
2973 @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}
2975 All the parameters but @var{scale_params} need to be explicitly
2978 Follows the list of the accepted parameters.
2983 Specify the width and height of the buffered video frames.
2985 @item pix_fmt_string
2986 A string representing the pixel format of the buffered video frames.
2987 It may be a number corresponding to a pixel format, or a pixel format
2990 @item timebase_num, timebase_den
2991 Specify numerator and denomitor of the timebase assumed by the
2992 timestamps of the buffered frames.
2994 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2995 Specify numerator and denominator of the sample aspect ratio assumed
2996 by the video frames.
2999 Specify the optional parameters to be used for the scale filter which
3000 is automatically inserted when an input change is detected in the
3001 input size or format.
3006 buffer=320:240:yuv410p:1:24:1:1
3009 will instruct the source to accept video frames with size 320x240 and
3010 with format "yuv410p", assuming 1/24 as the timestamps timebase and
3011 square pixels (1:1 sample aspect ratio).
3012 Since the pixel format with name "yuv410p" corresponds to the number 6
3013 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
3014 this example corresponds to:
3016 buffer=320:240:6:1:24:1:1
3021 Create a pattern generated by an elementary cellular automaton.
3023 The initial state of the cellular automaton can be defined through the
3024 @option{filename}, and @option{pattern} options. If such options are
3025 not specified an initial state is created randomly.
3027 At each new frame a new row in the video is filled with the result of
3028 the cellular automaton next generation. The behavior when the whole
3029 frame is filled is defined by the @option{scroll} option.
3031 This source accepts a list of options in the form of
3032 @var{key}=@var{value} pairs separated by ":". A description of the
3033 accepted options follows.
3037 Read the initial cellular automaton state, i.e. the starting row, from
3039 In the file, each non-whitespace character is considered an alive
3040 cell, a newline will terminate the row, and further characters in the
3041 file will be ignored.
3044 Read the initial cellular automaton state, i.e. the starting row, from
3045 the specified string.
3047 Each non-whitespace character in the string is considered an alive
3048 cell, a newline will terminate the row, and further characters in the
3049 string will be ignored.
3052 Set the video rate, that is the number of frames generated per second.
3055 @item random_fill_ratio, ratio
3056 Set the random fill ratio for the initial cellular automaton row. It
3057 is a floating point number value ranging from 0 to 1, defaults to
3060 This option is ignored when a file or a pattern is specified.
3062 @item random_seed, seed
3063 Set the seed for filling randomly the initial row, must be an integer
3064 included between 0 and UINT32_MAX. If not specified, or if explicitly
3065 set to -1, the filter will try to use a good random seed on a best
3069 Set the cellular automaton rule, it is a number ranging from 0 to 255.
3070 Default value is 110.
3073 Set the size of the output video.
3075 If @option{filename} or @option{pattern} is specified, the size is set
3076 by default to the width of the specified initial state row, and the
3077 height is set to @var{width} * PHI.
3079 If @option{size} is set, it must contain the width of the specified
3080 pattern string, and the specified pattern will be centered in the
3083 If a filename or a pattern string is not specified, the size value
3084 defaults to "320x518" (used for a randomly generated initial state).
3087 If set to 1, scroll the output upward when all the rows in the output
3088 have been already filled. If set to 0, the new generated row will be
3089 written over the top row just after the bottom row is filled.
3092 @item start_full, full
3093 If set to 1, completely fill the output with generated rows before
3094 outputting the first frame.
3095 This is the default behavior, for disabling set the value to 0.
3098 If set to 1, stitch the left and right row edges together.
3099 This is the default behavior, for disabling set the value to 0.
3102 @subsection Examples
3106 Read the initial state from @file{pattern}, and specify an output of
3109 cellauto=f=pattern:s=200x400
3113 Generate a random initial row with a width of 200 cells, with a fill
3116 cellauto=ratio=2/3:s=200x200
3120 Create a pattern generated by rule 18 starting by a single alive cell
3121 centered on an initial row with width 100:
3123 cellauto=p=@@:s=100x400:full=0:rule=18
3127 Specify a more elaborated initial pattern:
3129 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
3136 Provide an uniformly colored input.
3138 It accepts the following parameters:
3139 @var{color}:@var{frame_size}:@var{frame_rate}
3141 Follows the description of the accepted parameters.
3146 Specify the color of the source. It can be the name of a color (case
3147 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
3148 alpha specifier. The default value is "black".
3151 Specify the size of the sourced video, it may be a string of the form
3152 @var{width}x@var{height}, or the name of a size abbreviation. The
3153 default value is "320x240".
3156 Specify the frame rate of the sourced video, as the number of frames
3157 generated per second. It has to be a string in the format
3158 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3159 number or a valid video frame rate abbreviation. The default value is
3164 For example the following graph description will generate a red source
3165 with an opacity of 0.2, with size "qcif" and a frame rate of 10
3166 frames per second, which will be overlayed over the source connected
3167 to the pad with identifier "in".
3170 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
3175 Read a video stream from a movie container.
3177 It accepts the syntax: @var{movie_name}[:@var{options}] where
3178 @var{movie_name} is the name of the resource to read (not necessarily
3179 a file but also a device or a stream accessed through some protocol),
3180 and @var{options} is an optional sequence of @var{key}=@var{value}
3181 pairs, separated by ":".
3183 The description of the accepted options follows.
3187 @item format_name, f
3188 Specifies the format assumed for the movie to read, and can be either
3189 the name of a container or an input device. If not specified the
3190 format is guessed from @var{movie_name} or by probing.
3192 @item seek_point, sp
3193 Specifies the seek point in seconds, the frames will be output
3194 starting from this seek point, the parameter is evaluated with
3195 @code{av_strtod} so the numerical value may be suffixed by an IS
3196 postfix. Default value is "0".
3198 @item stream_index, si
3199 Specifies the index of the video stream to read. If the value is -1,
3200 the best suited video stream will be automatically selected. Default
3204 Specifies how many times to read the video stream in sequence.
3205 If the value is less than 1, the stream will be read again and again.
3206 Default value is "1".
3208 Note that when the movie is looped the source timestamps are not
3209 changed, so it will generate non monotonically increasing timestamps.
3212 This filter allows to overlay a second video on top of main input of
3213 a filtergraph as shown in this graph:
3215 input -----------> deltapts0 --> overlay --> output
3218 movie --> scale--> deltapts1 -------+
3221 Some examples follow:
3223 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
3224 # on top of the input labelled as "in".
3225 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3226 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3228 # read from a video4linux2 device, and overlay it on top of the input
3230 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
3231 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
3237 Generate various test patterns, as generated by the MPlayer test filter.
3239 The size of the generated video is fixed, and is 256x256.
3240 This source is useful in particular for testing encoding features.
3242 This source accepts an optional sequence of @var{key}=@var{value} pairs,
3243 separated by ":". The description of the accepted options follows.
3248 Specify the frame rate of the sourced video, as the number of frames
3249 generated per second. It has to be a string in the format
3250 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3251 number or a valid video frame rate abbreviation. The default value is
3255 Set the video duration of the sourced video. The accepted syntax is:
3257 [-]HH[:MM[:SS[.m...]]]
3260 See also the function @code{av_parse_time()}.
3262 If not specified, or the expressed duration is negative, the video is
3263 supposed to be generated forever.
3267 Set the number or the name of the test to perform. Supported tests are:
3282 Default value is "all", which will cycle through the list of all tests.
3285 For example the following:
3290 will generate a "dc_luma" test pattern.
3294 Provide a frei0r source.
3296 To enable compilation of this filter you need to install the frei0r
3297 header and configure FFmpeg with @code{--enable-frei0r}.
3299 The source supports the syntax:
3301 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
3304 @var{size} is the size of the video to generate, may be a string of the
3305 form @var{width}x@var{height} or a frame size abbreviation.
3306 @var{rate} is the rate of the video to generate, may be a string of
3307 the form @var{num}/@var{den} or a frame rate abbreviation.
3308 @var{src_name} is the name to the frei0r source to load. For more
3309 information regarding frei0r and how to set the parameters read the
3310 section @ref{frei0r} in the description of the video filters.
3312 Some examples follow:
3314 # generate a frei0r partik0l source with size 200x200 and frame rate 10
3315 # which is overlayed on the overlay filter main input
3316 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
3321 Generate a life pattern.
3323 This source is based on a generalization of John Conway's life game.
3325 The sourced input represents a life grid, each pixel represents a cell
3326 which can be in one of two possible states, alive or dead. Every cell
3327 interacts with its eight neighbours, which are the cells that are
3328 horizontally, vertically, or diagonally adjacent.
3330 At each interaction the grid evolves according to the adopted rule,
3331 which specifies the number of neighbor alive cells which will make a
3332 cell stay alive or born. The @option{rule} option allows to specify
3335 This source accepts a list of options in the form of
3336 @var{key}=@var{value} pairs separated by ":". A description of the
3337 accepted options follows.
3341 Set the file from which to read the initial grid state. In the file,
3342 each non-whitespace character is considered an alive cell, and newline
3343 is used to delimit the end of each row.
3345 If this option is not specified, the initial grid is generated
3349 Set the video rate, that is the number of frames generated per second.
3352 @item random_fill_ratio, ratio
3353 Set the random fill ratio for the initial random grid. It is a
3354 floating point number value ranging from 0 to 1, defaults to 1/PHI.
3355 It is ignored when a file is specified.
3357 @item random_seed, seed
3358 Set the seed for filling the initial random grid, must be an integer
3359 included between 0 and UINT32_MAX. If not specified, or if explicitly
3360 set to -1, the filter will try to use a good random seed on a best
3366 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
3367 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
3368 @var{NS} specifies the number of alive neighbor cells which make a
3369 live cell stay alive, and @var{NB} the number of alive neighbor cells
3370 which make a dead cell to become alive (i.e. to "born").
3371 "s" and "b" can be used in place of "S" and "B", respectively.
3373 Alternatively a rule can be specified by an 18-bits integer. The 9
3374 high order bits are used to encode the next cell state if it is alive
3375 for each number of neighbor alive cells, the low order bits specify
3376 the rule for "borning" new cells. Higher order bits encode for an
3377 higher number of neighbor cells.
3378 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
3379 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
3381 Default value is "S23/B3", which is the original Conway's game of life
3382 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
3383 cells, and will born a new cell if there are three alive cells around
3387 Set the size of the output video.
3389 If @option{filename} is specified, the size is set by default to the
3390 same size of the input file. If @option{size} is set, it must contain
3391 the size specified in the input file, and the initial grid defined in
3392 that file is centered in the larger resulting area.
3394 If a filename is not specified, the size value defaults to "320x240"
3395 (used for a randomly generated initial grid).
3398 If set to 1, stitch the left and right grid edges together, and the
3399 top and bottom edges also. Defaults to 1.
3402 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
3403 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
3404 value from 0 to 255.
3407 Set the color of living (or new born) cells.
3410 Set the color of dead cells. If @option{mold} is set, this is the first color
3411 used to represent a dead cell.
3414 Set mold color, for definitely dead and moldy cells.
3417 @subsection Examples
3421 Read a grid from @file{pattern}, and center it on a grid of size
3424 life=f=pattern:s=300x300
3428 Generate a random grid of size 200x200, with a fill ratio of 2/3:
3430 life=ratio=2/3:s=200x200
3434 Specify a custom rule for evolving a randomly generated grid:
3440 Full example with slow death effect (mold) using @command{ffplay}:
3442 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
3446 @section nullsrc, rgbtestsrc, testsrc
3448 The @code{nullsrc} source returns unprocessed video frames. It is
3449 mainly useful to be employed in analysis / debugging tools, or as the
3450 source for filters which ignore the input data.
3452 The @code{rgbtestsrc} source generates an RGB test pattern useful for
3453 detecting RGB vs BGR issues. You should see a red, green and blue
3454 stripe from top to bottom.
3456 The @code{testsrc} source generates a test video pattern, showing a
3457 color pattern, a scrolling gradient and a timestamp. This is mainly
3458 intended for testing purposes.
3460 These sources accept an optional sequence of @var{key}=@var{value} pairs,
3461 separated by ":". The description of the accepted options follows.
3466 Specify the size of the sourced video, it may be a string of the form
3467 @var{width}x@var{height}, or the name of a size abbreviation. The
3468 default value is "320x240".
3471 Specify the frame rate of the sourced video, as the number of frames
3472 generated per second. It has to be a string in the format
3473 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3474 number or a valid video frame rate abbreviation. The default value is
3478 Set the sample aspect ratio of the sourced video.
3481 Set the video duration of the sourced video. The accepted syntax is:
3483 [-]HH[:MM[:SS[.m...]]]
3486 See also the function @code{av_parse_time()}.
3488 If not specified, or the expressed duration is negative, the video is
3489 supposed to be generated forever.
3492 Set the number of decimals to show in the timestamp, only used in the
3493 @code{testsrc} source.
3495 The displayed timestamp value will correspond to the original
3496 timestamp value multiplied by the power of 10 of the specified
3497 value. Default value is 0.
3500 For example the following:
3502 testsrc=duration=5.3:size=qcif:rate=10
3505 will generate a video with a duration of 5.3 seconds, with size
3506 176x144 and a frame rate of 10 frames per second.
3508 If the input content is to be ignored, @code{nullsrc} can be used. The
3509 following command generates noise in the luminance plane by employing
3510 the @code{mp=geq} filter:
3512 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
3515 @c man end VIDEO SOURCES
3517 @chapter Video Sinks
3518 @c man begin VIDEO SINKS
3520 Below is a description of the currently available video sinks.
3524 Buffer video frames, and make them available to the end of the filter
3527 This sink is mainly intended for a programmatic use, in particular
3528 through the interface defined in @file{libavfilter/buffersink.h}.
3530 It does not require a string parameter in input, but you need to
3531 specify a pointer to a list of supported pixel formats terminated by
3532 -1 in the opaque parameter provided to @code{avfilter_init_filter}
3533 when initializing this sink.
3537 Null video sink, do absolutely nothing with the input video. It is
3538 mainly useful as a template and to be employed in analysis / debugging
3541 @c man end VIDEO SINKS