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{avconv} and @option{-vf} in @command{avplay}, and by the
23 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
24 @file{libavfilter/avfilter.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. It may have one of the two allowed forms:
48 A ':'-separated list of @var{key=value} pairs.
51 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
52 the option names in the order they are declared. E.g. the @code{fade} filter
53 declares three options in this order -- @option{type}, @option{start_frame} and
54 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
55 @var{in} is assigned to the option @option{type}, @var{0} to
56 @option{start_frame} and @var{30} to @option{nb_frames}.
60 If the option value itself is a list of items (e.g. the @code{format} filter
61 takes a list of pixel formats), the items in the list are usually separated by
64 The list of arguments can be quoted using the character "'" as initial
65 and ending mark, and the character '\' for escaping the characters
66 within the quoted text; otherwise the argument string is considered
67 terminated when the next special character (belonging to the set
68 "[]=;,") is encountered.
70 The name and arguments of the filter are optionally preceded and
71 followed by a list of link labels.
72 A link label allows to name a link and associate it to a filter output
73 or input pad. The preceding labels @var{in_link_1}
74 ... @var{in_link_N}, are associated to the filter input pads,
75 the following labels @var{out_link_1} ... @var{out_link_M}, are
76 associated to the output pads.
78 When two link labels with the same name are found in the
79 filtergraph, a link between the corresponding input and output pad is
82 If an output pad is not labelled, it is linked by default to the first
83 unlabelled input pad of the next filter in the filterchain.
84 For example in the filterchain:
86 nullsrc, split[L1], [L2]overlay, nullsink
88 the split filter instance has two output pads, and the overlay filter
89 instance two input pads. The first output pad of split is labelled
90 "L1", the first input pad of overlay is labelled "L2", and the second
91 output pad of split is linked to the second input pad of overlay,
92 which are both unlabelled.
94 In a complete filterchain all the unlabelled filter input and output
95 pads must be connected. A filtergraph is considered valid if all the
96 filter input and output pads of all the filterchains are connected.
98 Libavfilter will automatically insert @ref{scale} filters where format
99 conversion is required. It is possible to specify swscale flags
100 for those automatically inserted scalers by prepending
101 @code{sws_flags=@var{flags};}
102 to the filtergraph description.
104 Follows a BNF description for the filtergraph syntax:
106 @var{NAME} ::= sequence of alphanumeric characters and '_'
107 @var{LINKLABEL} ::= "[" @var{NAME} "]"
108 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
109 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
110 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
111 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
112 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
115 @c man end FILTERGRAPH DESCRIPTION
117 @chapter Audio Filters
118 @c man begin AUDIO FILTERS
120 When you configure your Libav build, you can disable any of the
121 existing filters using --disable-filters.
122 The configure output will show the audio filters included in your
125 Below is a description of the currently available audio filters.
129 Convert the input audio to one of the specified formats. The framework will
130 negotiate the most appropriate format to minimize conversions.
132 The filter accepts the following named parameters:
136 A '|'-separated list of requested sample formats.
139 A '|'-separated list of requested sample rates.
141 @item channel_layouts
142 A '|'-separated list of requested channel layouts.
146 If a parameter is omitted, all values are allowed.
148 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
150 aformat=sample_fmts=u8|s16:channel_layouts=stereo
155 Mixes multiple audio inputs into a single output.
159 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
161 will mix 3 input audio streams to a single output with the same duration as the
162 first input and a dropout transition time of 3 seconds.
164 The filter accepts the following named parameters:
168 Number of inputs. If unspecified, it defaults to 2.
171 How to determine the end-of-stream.
175 Duration of longest input. (default)
178 Duration of shortest input.
181 Duration of first input.
185 @item dropout_transition
186 Transition time, in seconds, for volume renormalization when an input
187 stream ends. The default value is 2 seconds.
193 Pass the audio source unchanged to the output.
197 Change the PTS (presentation timestamp) of the input audio frames.
199 This filter accepts the following options:
204 The expression which is evaluated for each frame to construct its timestamp.
208 The expression is evaluated through the eval API and can contain the following
213 the presentation timestamp in input
225 Number of the audio samples pass through the filter so far, starting at 0.
228 Number of the audio samples in the current frame.
234 the PTS of the first frame
243 wallclock (RTC) time in microseconds
246 wallclock (RTC) time at the start of the movie in microseconds
250 Some examples follow:
253 # start counting PTS from zero
254 asetpts=expr=PTS-STARTPTS
256 #generate timestamps by counting samples
259 # generate timestamps from a "live source" and rebase onto the current timebase
260 asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
266 Show a line containing various information for each input audio frame.
267 The input audio is not modified.
269 The shown line contains a sequence of key/value pairs of the form
270 @var{key}:@var{value}.
272 A description of each shown parameter follows:
276 sequential number of the input frame, starting from 0
279 Presentation timestamp of the input frame, in time base units; the time base
280 depends on the filter input pad, and is usually 1/@var{sample_rate}.
283 presentation timestamp of the input frame in seconds
292 sample rate for the audio frame
295 number of samples (per channel) in the frame
298 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
299 the data is treated as if all the planes were concatenated.
301 @item plane_checksums
302 A list of Adler-32 checksums for each data plane.
307 Split input audio into several identical outputs.
309 The filter accepts a single parameter which specifies the number of outputs. If
310 unspecified, it defaults to 2.
314 avconv -i INPUT -filter_complex asplit=5 OUTPUT
316 will create 5 copies of the input audio.
319 Synchronize audio data with timestamps by squeezing/stretching it and/or
320 dropping samples/adding silence when needed.
322 The filter accepts the following named parameters:
326 Enable stretching/squeezing the data to make it match the timestamps. Disabled
327 by default. When disabled, time gaps are covered with silence.
330 Minimum difference between timestamps and audio data (in seconds) to trigger
331 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
332 this filter, try setting this parameter to 0.
335 Maximum compensation in samples per second. Relevant only with compensate=1.
339 Assume the first pts should be this value. The time base is 1 / sample rate.
340 This allows for padding/trimming at the start of stream. By default, no
341 assumption is made about the first frame's expected pts, so no padding or
342 trimming is done. For example, this could be set to 0 to pad the beginning with
343 silence if an audio stream starts after the video stream or to trim any samples
344 with a negative pts due to encoder delay.
349 Trim the input so that the output contains one continuous subpart of the input.
351 This filter accepts the following options:
354 Timestamp (in seconds) of the start of the kept section. I.e. the audio sample
355 with the timestamp @var{start} will be the first sample in the output.
358 Timestamp (in seconds) of the first audio sample that will be dropped. I.e. the
359 audio sample immediately preceding the one with the timestamp @var{end} will be
360 the last sample in the output.
363 Same as @var{start}, except this option sets the start timestamp in samples
367 Same as @var{end}, except this option sets the end timestamp in samples instead
371 Maximum duration of the output in seconds.
374 Number of the first sample that should be passed to output.
377 Number of the first sample that should be dropped.
380 Note that the first two sets of the start/end options and the @option{duration}
381 option look at the frame timestamp, while the _sample options simply count the
382 samples that pass through the filter. So start/end_pts and start/end_sample will
383 give different results when the timestamps are wrong, inexact or do not start at
384 zero. Also note that this filter does not modify the timestamps. If you wish
385 that the output timestamps start at zero, insert the asetpts filter after the
388 If multiple start or end options are set, this filter tries to be greedy and
389 keep all samples that match at least one of the specified constraints. To keep
390 only the part that matches all the constraints at once, chain multiple atrim
393 The defaults are such that all the input is kept. So it is possible to set e.g.
394 just the end values to keep everything before the specified time.
399 drop everything except the second minute of input
401 avconv -i INPUT -af atrim=60:120
405 keep only the first 1000 samples
407 avconv -i INPUT -af atrim=end_sample=1000
412 @section channelsplit
413 Split each channel in input audio stream into a separate output stream.
415 This filter accepts the following named parameters:
418 Channel layout of the input stream. Default is "stereo".
421 For example, assuming a stereo input MP3 file
423 avconv -i in.mp3 -filter_complex channelsplit out.mkv
425 will create an output Matroska file with two audio streams, one containing only
426 the left channel and the other the right channel.
428 To split a 5.1 WAV file into per-channel files
430 avconv -i in.wav -filter_complex
431 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
432 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
433 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
438 Remap input channels to new locations.
440 This filter accepts the following named parameters:
443 Channel layout of the output stream.
446 Map channels from input to output. The argument is a '|'-separated list of
447 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
448 @var{in_channel} form. @var{in_channel} can be either the name of the input
449 channel (e.g. FL for front left) or its index in the input channel layout.
450 @var{out_channel} is the name of the output channel or its index in the output
451 channel layout. If @var{out_channel} is not given then it is implicitly an
452 index, starting with zero and increasing by one for each mapping.
455 If no mapping is present, the filter will implicitly map input channels to
456 output channels preserving index.
458 For example, assuming a 5.1+downmix input MOV file
460 avconv -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
462 will create an output WAV file tagged as stereo from the downmix channels of
465 To fix a 5.1 WAV improperly encoded in AAC's native channel order
467 avconv -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
471 Compress or expand audio dynamic range.
473 A description of the accepted options follows.
479 Set list of times in seconds for each channel over which the instantaneous level
480 of the input signal is averaged to determine its volume. @var{attacks} refers to
481 increase of volume and @var{decays} refers to decrease of volume. For most
482 situations, the attack time (response to the audio getting louder) should be
483 shorter than the decay time because the human ear is more sensitive to sudden
484 loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
485 a typical value for decay is 0.8 seconds.
488 Set list of points for the transfer function, specified in dB relative to the
489 maximum possible signal amplitude. Each key points list must be defined using
490 the following syntax: @code{x0/y0|x1/y1|x2/y2|....}
492 The input values must be in strictly increasing order but the transfer function
493 does not have to be monotonically rising. The point @code{0/0} is assumed but
494 may be overridden (by @code{0/out-dBn}). Typical values for the transfer
495 function are @code{-70/-70|-60/-20}.
498 Set the curve radius in dB for all joints. Defaults to 0.01.
501 Set additional gain in dB to be applied at all points on the transfer function.
502 This allows easy adjustment of the overall gain. Defaults to 0.
505 Set initial volume in dB to be assumed for each channel when filtering starts.
506 This permits the user to supply a nominal level initially, so that, for
507 example, a very large gain is not applied to initial signal levels before the
508 companding has begun to operate. A typical value for audio which is initially
509 quiet is -90 dB. Defaults to 0.
512 Set delay in seconds. The input audio is analyzed immediately, but audio is
513 delayed before being fed to the volume adjuster. Specifying a delay
514 approximately equal to the attack/decay times allows the filter to effectively
515 operate in predictive rather than reactive mode. Defaults to 0.
523 Make music with both quiet and loud passages suitable for listening in a noisy
526 compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
530 Noise gate for when the noise is at a lower level than the signal:
532 compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
536 Here is another noise gate, this time for when the noise is at a higher level
537 than the signal (making it, in some ways, similar to squelch):
539 compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
544 Join multiple input streams into one multi-channel stream.
546 The filter accepts the following named parameters:
550 Number of input streams. Defaults to 2.
553 Desired output channel layout. Defaults to stereo.
556 Map channels from inputs to output. The argument is a '|'-separated list of
557 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
558 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
559 can be either the name of the input channel (e.g. FL for front left) or its
560 index in the specified input stream. @var{out_channel} is the name of the output
564 The filter will attempt to guess the mappings when those are not specified
565 explicitly. It does so by first trying to find an unused matching input channel
566 and if that fails it picks the first unused input channel.
568 E.g. to join 3 inputs (with properly set channel layouts)
570 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
573 To build a 5.1 output from 6 single-channel streams:
575 avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
576 'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
581 Convert the audio sample format, sample rate and channel layout. This filter is
582 not meant to be used directly, it is inserted automatically by libavfilter
583 whenever conversion is needed. Use the @var{aformat} filter to force a specific
588 Adjust the input audio volume.
590 The filter accepts the following named parameters:
594 Expresses how the audio volume will be increased or decreased.
596 Output values are clipped to the maximum value.
598 The output audio volume is given by the relation:
600 @var{output_volume} = @var{volume} * @var{input_volume}
603 Default value for @var{volume} is 1.0.
606 Mathematical precision.
608 This determines which input sample formats will be allowed, which affects the
609 precision of the volume scaling.
613 8-bit fixed-point; limits input sample format to U8, S16, and S32.
615 32-bit floating-point; limits input sample format to FLT. (default)
617 64-bit floating-point; limits input sample format to DBL.
621 Behaviour on encountering ReplayGain side data in input frames.
625 Remove ReplayGain side data, ignoring its contents (the default).
628 Ignore ReplayGain side data, but leave it in the frame.
631 Prefer track gain, if present.
634 Prefer album gain, if present.
637 @item replaygain_preamp
638 Pre-amplification gain in dB to apply to the selected replaygain gain.
640 Default value for @var{replaygain_preamp} is 0.0.
648 Halve the input audio volume:
652 volume=volume=-6.0206dB
656 Increase input audio power by 6 decibels using fixed-point precision:
658 volume=volume=6dB:precision=fixed
662 @c man end AUDIO FILTERS
664 @chapter Audio Sources
665 @c man begin AUDIO SOURCES
667 Below is a description of the currently available audio sources.
671 Null audio source, never return audio frames. It is mainly useful as a
672 template and to be employed in analysis / debugging tools.
674 It accepts as optional parameter a string of the form
675 @var{sample_rate}:@var{channel_layout}.
677 @var{sample_rate} specify the sample rate, and defaults to 44100.
679 @var{channel_layout} specify the channel layout, and can be either an
680 integer or a string representing a channel layout. The default value
681 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
683 Check the channel_layout_map definition in
684 @file{libavutil/channel_layout.c} for the mapping between strings and
685 channel layout values.
687 Follow some examples:
689 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
697 Buffer audio frames, and make them available to the filter chain.
699 This source is not intended to be part of user-supplied graph descriptions but
700 for insertion by calling programs through the interface defined in
701 @file{libavfilter/buffersrc.h}.
703 It accepts the following named parameters:
707 Timebase which will be used for timestamps of submitted frames. It must be
708 either a floating-point number or in @var{numerator}/@var{denominator} form.
714 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
717 Channel layout of the audio data, in the form that can be accepted by
718 @code{av_get_channel_layout()}.
721 All the parameters need to be explicitly defined.
723 @c man end AUDIO SOURCES
726 @c man begin AUDIO SINKS
728 Below is a description of the currently available audio sinks.
732 Null audio sink, do absolutely nothing with the input audio. It is
733 mainly useful as a template and to be employed in analysis / debugging
737 This sink is intended for programmatic use. Frames that arrive on this sink can
738 be retrieved by the calling program using the interface defined in
739 @file{libavfilter/buffersink.h}.
741 This filter accepts no parameters.
743 @c man end AUDIO SINKS
745 @chapter Video Filters
746 @c man begin VIDEO FILTERS
748 When you configure your Libav build, you can disable any of the
749 existing filters using --disable-filters.
750 The configure output will show the video filters included in your
753 Below is a description of the currently available video filters.
757 Detect frames that are (almost) completely black. Can be useful to
758 detect chapter transitions or commercials. Output lines consist of
759 the frame number of the detected frame, the percentage of blackness,
760 the position in the file if known or -1 and the timestamp in seconds.
762 In order to display the output lines, you need to set the loglevel at
763 least to the AV_LOG_INFO value.
765 The filter accepts the following options:
770 The percentage of the pixels that have to be below the threshold, defaults to
774 Threshold below which a pixel value is considered black, defaults to 32.
780 Apply boxblur algorithm to the input video.
782 This filter accepts the following options:
795 Chroma and alpha parameters are optional, if not specified they default
796 to the corresponding values set for @var{luma_radius} and
799 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
800 the radius in pixels of the box used for blurring the corresponding
801 input plane. They are expressions, and can contain the following
805 the input width and height in pixels
808 the input chroma image width and height in pixels
811 horizontal and vertical chroma subsample values. For example for the
812 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
815 The radius must be a non-negative number, and must not be greater than
816 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
817 and of @code{min(cw,ch)/2} for the chroma planes.
819 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
820 how many times the boxblur filter is applied to the corresponding
823 Some examples follow:
828 Apply a boxblur filter with luma, chroma, and alpha radius
831 boxblur=luma_radius=2:luma_power=1
835 Set luma radius to 2, alpha and chroma radius to 0
841 Set luma and chroma radius to a fraction of the video dimension
843 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
850 Copy the input source unchanged to the output. Mainly useful for
855 Crop the input video to given dimensions.
857 This filter accepts the following options:
862 Width of the output video.
865 Height of the output video.
868 Horizontal position, in the input video, of the left edge of the output video.
871 Vertical position, in the input video, of the top edge of the output video.
875 The parameters are expressions containing the following constants:
879 the corresponding mathematical approximated values for e
880 (euler number), pi (greek PI), PHI (golden ratio)
883 the computed values for @var{x} and @var{y}. They are evaluated for
887 the input width and height
890 same as @var{in_w} and @var{in_h}
893 the output (cropped) width and height
896 same as @var{out_w} and @var{out_h}
899 the number of input frame, starting from 0
902 timestamp expressed in seconds, NAN if the input timestamp is unknown
906 The @var{out_w} and @var{out_h} parameters specify the expressions for
907 the width and height of the output (cropped) video. They are
908 evaluated just at the configuration of the filter.
910 The default value of @var{out_w} is "in_w", and the default value of
911 @var{out_h} is "in_h".
913 The expression for @var{out_w} may depend on the value of @var{out_h},
914 and the expression for @var{out_h} may depend on @var{out_w}, but they
915 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
916 evaluated after @var{out_w} and @var{out_h}.
918 The @var{x} and @var{y} parameters specify the expressions for the
919 position of the top-left corner of the output (non-cropped) area. They
920 are evaluated for each frame. If the evaluated value is not valid, it
921 is approximated to the nearest valid value.
923 The default value of @var{x} is "(in_w-out_w)/2", and the default
924 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
925 the center of the input image.
927 The expression for @var{x} may depend on @var{y}, and the expression
928 for @var{y} may depend on @var{x}.
930 Follow some examples:
932 # crop the central input area with size 100x100
933 crop=out_w=100:out_h=100
935 # crop the central input area with size 2/3 of the input video
936 "crop=out_w=2/3*in_w:out_h=2/3*in_h"
938 # crop the input video central square
941 # delimit the rectangle with the top-left corner placed at position
942 # 100:100 and the right-bottom corner corresponding to the right-bottom
943 # corner of the input image.
944 crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
946 # crop 10 pixels from the left and right borders, and 20 pixels from
947 # the top and bottom borders
948 "crop=out_w=in_w-2*10:out_h=in_h-2*20"
950 # keep only the bottom right quarter of the input image
951 "crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
953 # crop height for getting Greek harmony
954 "crop=out_w=in_w:out_h=1/PHI*in_w"
957 "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)"
959 # erratic camera effect depending on timestamp
960 "crop=out_w=in_w/2:out_h=in_h/2:x=(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):y=(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
962 # set x depending on the value of y
963 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
968 Auto-detect crop size.
970 Calculate necessary cropping parameters and prints the recommended
971 parameters through the logging system. The detected dimensions
972 correspond to the non-black area of the input video.
974 This filter accepts the following options:
979 Threshold, which can be optionally specified from nothing (0) to
980 everything (255), defaults to 24.
983 Value which the width/height should be divisible by, defaults to
984 16. The offset is automatically adjusted to center the video. Use 2 to
985 get only even dimensions (needed for 4:2:2 video). 16 is best when
986 encoding to most video codecs.
989 Counter that determines after how many frames cropdetect will reset
990 the previously detected largest video area and start over to detect
991 the current optimal crop area. Defaults to 0.
993 This can be useful when channel logos distort the video area. 0
994 indicates never reset and return the largest area encountered during
1000 Suppress a TV station logo by a simple interpolation of the surrounding
1001 pixels. Just set a rectangle covering the logo and watch it disappear
1002 (and sometimes something even uglier appear - your mileage may vary).
1004 This filter accepts the following options:
1008 Specify the top left corner coordinates of the logo. They must be
1012 Specify the width and height of the logo to clear. They must be
1016 Specify the thickness of the fuzzy edge of the rectangle (added to
1017 @var{w} and @var{h}). The default value is 4.
1020 When set to 1, a green rectangle is drawn on the screen to simplify
1021 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1022 @var{band} is set to 4. The default value is 0.
1026 Some examples follow.
1031 Set a rectangle covering the area with top left corner coordinates 0,0
1032 and size 100x77, setting a band of size 10:
1034 delogo=x=0:y=0:w=100:h=77:band=10
1041 Draw a colored box on the input image.
1043 This filter accepts the following options:
1048 Specify the top left corner coordinates of the box. Default to 0.
1051 Specify the width and height of the box, if 0 they are interpreted as
1052 the input width and height. Default to 0.
1055 Specify the color of the box to write, it can be the name of a color
1056 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1059 Follow some examples:
1061 # draw a black box around the edge of the input image
1064 # draw a box with color red and an opacity of 50%
1065 drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
1070 Draw text string or text from specified file on top of video using the
1071 libfreetype library.
1073 To enable compilation of this filter you need to configure Libav with
1074 @code{--enable-libfreetype}.
1076 The filter also recognizes strftime() sequences in the provided text
1077 and expands them accordingly. Check the documentation of strftime().
1079 The description of the accepted parameters follows.
1084 The font file to be used for drawing text. Path must be included.
1085 This parameter is mandatory.
1088 The text string to be drawn. The text must be a sequence of UTF-8
1090 This parameter is mandatory if no file is specified with the parameter
1094 A text file containing text to be drawn. The text must be a sequence
1095 of UTF-8 encoded characters.
1097 This parameter is mandatory if no text string is specified with the
1098 parameter @var{text}.
1100 If both text and textfile are specified, an error is thrown.
1103 The offsets where text will be drawn within the video frame.
1104 Relative to the top/left border of the output image.
1105 They accept expressions similar to the @ref{overlay} filter:
1109 the computed values for @var{x} and @var{y}. They are evaluated for
1112 @item main_w, main_h
1113 main input width and height
1116 same as @var{main_w} and @var{main_h}
1118 @item text_w, text_h
1119 rendered text width and height
1122 same as @var{text_w} and @var{text_h}
1125 the number of frames processed, starting from 0
1128 timestamp expressed in seconds, NAN if the input timestamp is unknown
1132 The default value of @var{x} and @var{y} is 0.
1135 The font size to be used for drawing text.
1136 The default value of @var{fontsize} is 16.
1139 The color to be used for drawing fonts.
1140 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1141 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1142 The default value of @var{fontcolor} is "black".
1145 The color to be used for drawing box around text.
1146 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1147 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1148 The default value of @var{boxcolor} is "white".
1151 Used to draw a box around text using background color.
1152 Value should be either 1 (enable) or 0 (disable).
1153 The default value of @var{box} is 0.
1155 @item shadowx, shadowy
1156 The x and y offsets for the text shadow position with respect to the
1157 position of the text. They can be either positive or negative
1158 values. Default value for both is "0".
1161 The color to be used for drawing a shadow behind the drawn text. It
1162 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1163 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1164 The default value of @var{shadowcolor} is "black".
1167 Flags to be used for loading the fonts.
1169 The flags map the corresponding flags supported by libfreetype, and are
1170 a combination of the following values:
1177 @item vertical_layout
1178 @item force_autohint
1181 @item ignore_global_advance_width
1183 @item ignore_transform
1190 Default value is "render".
1192 For more information consult the documentation for the FT_LOAD_*
1196 The size in number of spaces to use for rendering the tab.
1200 If true, check and fix text coords to avoid clipping.
1203 For example the command:
1205 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1208 will draw "Test Text" with font FreeSerif, using the default values
1209 for the optional parameters.
1213 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1214 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1217 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
1218 and y=50 (counting from the top-left corner of the screen), text is
1219 yellow with a red box around it. Both the text and the box have an
1222 Note that the double quotes are not necessary if spaces are not used
1223 within the parameter list.
1225 For more information about libfreetype, check:
1226 @url{http://www.freetype.org/}.
1230 Apply fade-in/out effect to input video.
1232 This filter accepts the following options:
1237 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
1241 The number of the start frame for starting to apply the fade effect.
1244 The number of frames for which the fade effect has to last. At the end of the
1245 fade-in effect the output video will have the same intensity as the input video,
1246 at the end of the fade-out transition the output video will be completely black.
1250 A few usage examples follow, usable too as test scenarios.
1252 # fade in first 30 frames of video
1253 fade=type=in:nb_frames=30
1255 # fade out last 45 frames of a 200-frame video
1256 fade=type=out:start_frame=155:nb_frames=45
1258 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1259 fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
1261 # make first 5 frames black, then fade in from frame 5-24
1262 fade=type=in:start_frame=5:nb_frames=20
1267 Transform the field order of the input video.
1269 This filter accepts the following options:
1274 Output field order. Valid values are @var{tff} for top field first or @var{bff}
1275 for bottom field first.
1278 Default value is "tff".
1280 Transformation is achieved by shifting the picture content up or down
1281 by one line, and filling the remaining line with appropriate picture content.
1282 This method is consistent with most broadcast field order converters.
1284 If the input video is not flagged as being interlaced, or it is already
1285 flagged as being of the required output field order then this filter does
1286 not alter the incoming video.
1288 This filter is very useful when converting to or from PAL DV material,
1289 which is bottom field first.
1293 ./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
1298 Buffer input images and send them when they are requested.
1300 This filter is mainly useful when auto-inserted by the libavfilter
1303 The filter does not take parameters.
1307 Convert the input video to one of the specified pixel formats.
1308 Libavfilter will try to pick one that is supported for the input to
1311 This filter accepts the following parameters:
1315 A '|'-separated list of pixel format names, for example
1316 "pix_fmts=yuv420p|monow|rgb24".
1320 Some examples follow:
1322 # convert the input video to the format "yuv420p"
1323 format=pix_fmts=yuv420p
1325 # convert the input video to any of the formats in the list
1326 format=pix_fmts=yuv420p|yuv444p|yuv410p
1332 Convert the video to specified constant framerate by duplicating or dropping
1333 frames as necessary.
1335 This filter accepts the following named parameters:
1339 Desired output framerate.
1342 Assume the first PTS should be the given value, in seconds. This allows for
1343 padding/trimming at the start of stream. By default, no assumption is made
1344 about the first frame's expected PTS, so no padding or trimming is done.
1345 For example, this could be set to 0 to pad the beginning with duplicates of
1346 the first frame if a video stream starts after the audio stream or to trim any
1347 frames with a negative PTS.
1353 Pack two different video streams into a stereoscopic video, setting proper
1354 metadata on supported codecs. The two views should have the same size and
1355 framerate and processing will stop when the shorter video ends. Please note
1356 that you may conveniently adjust view properties with the @ref{scale} and
1359 This filter accepts the following named parameters:
1363 Desired packing format. Supported values are:
1368 Views are next to each other (default).
1371 Views are on top of each other.
1374 Views are packed by line.
1377 Views are eacked by column.
1380 Views are temporally interleaved.
1386 Some examples follow:
1389 # Convert left and right views into a frame sequential video.
1390 avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
1392 # Convert views into a side-by-side video with the same output resolution as the input.
1393 avconv -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
1399 Apply a frei0r effect to the input video.
1401 To enable compilation of this filter you need to install the frei0r
1402 header and configure Libav with --enable-frei0r.
1404 This filter accepts the following options:
1409 The name to the frei0r effect to load. If the environment variable
1410 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
1411 directories specified by the colon separated list in @env{FREIOR_PATH},
1412 otherwise in the standard frei0r paths, which are in this order:
1413 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
1414 @file{/usr/lib/frei0r-1/}.
1417 A '|'-separated list of parameters to pass to the frei0r effect.
1421 A frei0r effect parameter can be a boolean (whose values are specified
1422 with "y" and "n"), a double, a color (specified by the syntax
1423 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1424 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1425 description), a position (specified by the syntax @var{X}/@var{Y},
1426 @var{X} and @var{Y} being float numbers) and a string.
1428 The number and kind of parameters depend on the loaded effect. If an
1429 effect parameter is not specified the default value is set.
1431 Some examples follow:
1433 # apply the distort0r effect, set the first two double parameters
1434 frei0r=filter_name=distort0r:filter_params=0.5|0.01
1436 # apply the colordistance effect, takes a color as first parameter
1437 frei0r=colordistance:0.2/0.3/0.4
1438 frei0r=colordistance:violet
1439 frei0r=colordistance:0x112233
1441 # apply the perspective effect, specify the top left and top right
1443 frei0r=perspective:0.2/0.2|0.8/0.2
1446 For more information see:
1447 @url{http://piksel.org/frei0r}
1451 Fix the banding artifacts that are sometimes introduced into nearly flat
1452 regions by truncation to 8bit colordepth.
1453 Interpolate the gradients that should go where the bands are, and
1456 This filter is designed for playback only. Do not use it prior to
1457 lossy compression, because compression tends to lose the dither and
1458 bring back the bands.
1460 This filter accepts the following options:
1465 The maximum amount by which the filter will change any one pixel. Also the
1466 threshold for detecting nearly flat regions. Acceptable values range from .51 to
1467 64, default value is 1.2, out-of-range values will be clipped to the valid
1471 The neighborhood to fit the gradient to. A larger radius makes for smoother
1472 gradients, but also prevents the filter from modifying the pixels near detailed
1473 regions. Acceptable values are 8-32, default value is 16, out-of-range values
1474 will be clipped to the valid range.
1479 # default parameters
1480 gradfun=strength=1.2:radius=16
1488 Flip the input video horizontally.
1490 For example to horizontally flip the input video with @command{avconv}:
1492 avconv -i in.avi -vf "hflip" out.avi
1497 High precision/quality 3d denoise filter. This filter aims to reduce
1498 image noise producing smooth images and making still images really
1499 still. It should enhance compressibility.
1501 It accepts the following optional parameters:
1505 a non-negative float number which specifies spatial luma strength,
1508 @item chroma_spatial
1509 a non-negative float number which specifies spatial chroma strength,
1510 defaults to 3.0*@var{luma_spatial}/4.0
1513 a float number which specifies luma temporal strength, defaults to
1514 6.0*@var{luma_spatial}/4.0
1517 a float number which specifies chroma temporal strength, defaults to
1518 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1523 Simple interlacing filter from progressive contents. This interleaves upper (or
1524 lower) lines from odd frames with lower (or upper) lines from even frames,
1525 halving the frame rate and preserving image height. A vertical lowpass filter
1526 is always applied in order to avoid twitter effects and reduce moiré patterns.
1529 Original Original New Frame
1530 Frame 'j' Frame 'j+1' (tff)
1531 ========== =========== ==================
1532 Line 0 --------------------> Frame 'j' Line 0
1533 Line 1 Line 1 ----> Frame 'j+1' Line 1
1534 Line 2 ---------------------> Frame 'j' Line 2
1535 Line 3 Line 3 ----> Frame 'j+1' Line 3
1537 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
1540 It accepts the following optional parameters:
1544 determines whether the interlaced frame is taken from the even (tff - default)
1545 or odd (bff) lines of the progressive frame.
1548 @section lut, lutrgb, lutyuv
1550 Compute a look-up table for binding each pixel component input value
1551 to an output value, and apply it to input video.
1553 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1554 to an RGB input video.
1556 These filters accept the following options:
1558 @item @var{c0} (first pixel component)
1559 @item @var{c1} (second pixel component)
1560 @item @var{c2} (third pixel component)
1561 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
1563 @item @var{r} (red component)
1564 @item @var{g} (green component)
1565 @item @var{b} (blue component)
1566 @item @var{a} (alpha component)
1568 @item @var{y} (Y/luminance component)
1569 @item @var{u} (U/Cb component)
1570 @item @var{v} (V/Cr component)
1573 Each of them specifies the expression to use for computing the lookup table for
1574 the corresponding pixel component values.
1576 The exact component associated to each of the @var{c*} options depends on the
1579 The @var{lut} filter requires either YUV or RGB pixel formats in input,
1580 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
1582 The expressions can contain the following constants and functions:
1586 the corresponding mathematical approximated values for e
1587 (euler number), pi (greek PI), PHI (golden ratio)
1590 the input width and height
1593 input value for the pixel component
1596 the input value clipped in the @var{minval}-@var{maxval} range
1599 maximum value for the pixel component
1602 minimum value for the pixel component
1605 the negated value for the pixel component value clipped in the
1606 @var{minval}-@var{maxval} range , it corresponds to the expression
1607 "maxval-clipval+minval"
1610 the computed value in @var{val} clipped in the
1611 @var{minval}-@var{maxval} range
1613 @item gammaval(gamma)
1614 the computed gamma correction value of the pixel component value
1615 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1617 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1621 All expressions default to "val".
1623 Some examples follow:
1625 # negate input video
1626 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1627 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1629 # the above is the same as
1630 lutrgb="r=negval:g=negval:b=negval"
1631 lutyuv="y=negval:u=negval:v=negval"
1636 # remove chroma components, turns the video into a graytone image
1637 lutyuv="u=128:v=128"
1639 # apply a luma burning effect
1642 # remove green and blue components
1645 # set a constant alpha channel value on input
1646 format=rgba,lutrgb=a="maxval-minval/2"
1648 # correct luminance gamma by a 0.5 factor
1649 lutyuv=y=gammaval(0.5)
1656 This filter accepts an integer in input, if non-zero it negates the
1657 alpha component (if available). The default value in input is 0.
1661 Force libavfilter not to use any of the specified pixel formats for the
1662 input to the next filter.
1664 This filter accepts the following parameters:
1668 A '|'-separated list of pixel format names, for example
1669 "pix_fmts=yuv420p|monow|rgb24".
1673 Some examples follow:
1675 # force libavfilter to use a format different from "yuv420p" for the
1676 # input to the vflip filter
1677 noformat=pix_fmts=yuv420p,vflip
1679 # convert the input video to any of the formats not contained in the list
1680 noformat=yuv420p|yuv444p|yuv410p
1685 Pass the video source unchanged to the output.
1689 Apply video transform using libopencv.
1691 To enable this filter install libopencv library and headers and
1692 configure Libav with --enable-libopencv.
1694 This filter accepts the following parameters:
1699 The name of the libopencv filter to apply.
1702 The parameters to pass to the libopencv filter. If not specified the default
1707 Refer to the official libopencv documentation for more precise
1709 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1711 Follows the list of supported libopencv filters.
1716 Dilate an image by using a specific structuring element.
1717 This filter corresponds to the libopencv function @code{cvDilate}.
1719 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
1721 @var{struct_el} represents a structuring element, and has the syntax:
1722 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1724 @var{cols} and @var{rows} represent the number of columns and rows of
1725 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1726 point, and @var{shape} the shape for the structuring element, and
1727 can be one of the values "rect", "cross", "ellipse", "custom".
1729 If the value for @var{shape} is "custom", it must be followed by a
1730 string of the form "=@var{filename}". The file with name
1731 @var{filename} is assumed to represent a binary image, with each
1732 printable character corresponding to a bright pixel. When a custom
1733 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1734 or columns and rows of the read file are assumed instead.
1736 The default value for @var{struct_el} is "3x3+0x0/rect".
1738 @var{nb_iterations} specifies the number of times the transform is
1739 applied to the image, and defaults to 1.
1741 Follow some example:
1743 # use the default values
1746 # dilate using a structuring element with a 5x5 cross, iterate two times
1747 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
1749 # read the shape from the file diamond.shape, iterate two times
1750 # the file diamond.shape may contain a pattern of characters like this:
1756 # the specified cols and rows are ignored (but not the anchor point coordinates)
1757 ocv=dilate:0x0+2x2/custom=diamond.shape|2
1762 Erode an image by using a specific structuring element.
1763 This filter corresponds to the libopencv function @code{cvErode}.
1765 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1766 with the same syntax and semantics as the @ref{dilate} filter.
1770 Smooth the input video.
1772 The filter takes the following parameters:
1773 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
1775 @var{type} is the type of smooth filter to apply, and can be one of
1776 the following values: "blur", "blur_no_scale", "median", "gaussian",
1777 "bilateral". The default value is "gaussian".
1779 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1780 parameters whose meanings depend on smooth type. @var{param1} and
1781 @var{param2} accept integer positive values or 0, @var{param3} and
1782 @var{param4} accept float values.
1784 The default value for @var{param1} is 3, the default value for the
1785 other parameters is 0.
1787 These parameters correspond to the parameters assigned to the
1788 libopencv function @code{cvSmooth}.
1793 Overlay one video on top of another.
1795 It takes two inputs and one output, the first input is the "main"
1796 video on which the second input is overlayed.
1798 This filter accepts the following parameters:
1803 The horizontal position of the left edge of the overlaid video on the main video.
1806 The vertical position of the top edge of the overlaid video on the main video.
1810 The parameters are expressions containing the following parameters:
1813 @item main_w, main_h
1814 main input width and height
1817 same as @var{main_w} and @var{main_h}
1819 @item overlay_w, overlay_h
1820 overlay input width and height
1823 same as @var{overlay_w} and @var{overlay_h}
1826 The action to take when EOF is encountered on the secondary input, accepts one
1827 of the following values:
1831 repeat the last frame (the default)
1835 pass through the main input
1840 Be aware that frames are taken from each input video in timestamp
1841 order, hence, if their initial timestamps differ, it is a a good idea
1842 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1843 have them begin in the same zero timestamp, as it does the example for
1844 the @var{movie} filter.
1846 Follow some examples:
1848 # draw the overlay at 10 pixels from the bottom right
1849 # corner of the main video.
1850 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
1852 # insert a transparent PNG logo in the bottom left corner of the input
1853 avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
1855 # insert 2 different transparent PNG logos (second logo on bottom
1857 avconv -i input -i logo1 -i logo2 -filter_complex
1858 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
1860 # add a transparent color layer on top of the main video,
1861 # WxH specifies the size of the main input to the overlay filter
1862 color=red@.3:WxH [over]; [in][over] overlay [out]
1864 # mask 10-20 seconds of a video by applying the delogo filter to a section
1865 avconv -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
1866 -vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
1870 You can chain together more overlays but the efficiency of such
1871 approach is yet to be tested.
1875 Add paddings to the input image, and places the original input at the
1876 given coordinates @var{x}, @var{y}.
1878 This filter accepts the following parameters:
1883 Specify the size of the output image with the paddings added. If the
1884 value for @var{width} or @var{height} is 0, the corresponding input size
1885 is used for the output.
1887 The @var{width} expression can reference the value set by the
1888 @var{height} expression, and vice versa.
1890 The default value of @var{width} and @var{height} is 0.
1894 Specify the offsets where to place the input image in the padded area
1895 with respect to the top/left border of the output image.
1897 The @var{x} expression can reference the value set by the @var{y}
1898 expression, and vice versa.
1900 The default value of @var{x} and @var{y} is 0.
1904 Specify the color of the padded area, it can be the name of a color
1905 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1907 The default value of @var{color} is "black".
1911 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1912 expressions containing the following constants:
1916 the corresponding mathematical approximated values for e
1917 (euler number), pi (greek PI), phi (golden ratio)
1920 the input video width and height
1923 same as @var{in_w} and @var{in_h}
1926 the output width and height, that is the size of the padded area as
1927 specified by the @var{width} and @var{height} expressions
1930 same as @var{out_w} and @var{out_h}
1933 x and y offsets as specified by the @var{x} and @var{y}
1934 expressions, or NAN if not yet specified
1937 input display aspect ratio, same as @var{iw} / @var{ih}
1940 horizontal and vertical chroma subsample values. For example for the
1941 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1944 Some examples follow:
1947 # Add paddings with color "violet" to the input video. Output video
1948 # size is 640x480, the top-left corner of the input video is placed at
1950 pad=width=640:height=480:x=0:y=40:color=violet
1952 # pad the input to get an output with dimensions increased bt 3/2,
1953 # and put the input video at the center of the padded area
1954 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1956 # pad the input to get a squared output with size equal to the maximum
1957 # value between the input width and height, and put the input video at
1958 # the center of the padded area
1959 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1961 # pad the input to get a final w/h ratio of 16:9
1962 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1964 # double output size and put the input video in the bottom-right
1965 # corner of the output padded area
1966 pad="2*iw:2*ih:ow-iw:oh-ih"
1969 @section pixdesctest
1971 Pixel format descriptor test filter, mainly useful for internal
1972 testing. The output video should be equal to the input video.
1976 format=monow, pixdesctest
1979 can be used to test the monowhite pixel format descriptor definition.
1984 Scale the input video and/or convert the image format.
1986 This filter accepts the following options:
1994 Output video height.
1998 The parameters @var{w} and @var{h} are expressions containing
1999 the following constants:
2003 the corresponding mathematical approximated values for e
2004 (euler number), pi (greek PI), phi (golden ratio)
2007 the input width and height
2010 same as @var{in_w} and @var{in_h}
2013 the output (cropped) width and height
2016 same as @var{out_w} and @var{out_h}
2019 same as @var{iw} / @var{ih}
2022 input sample aspect ratio
2025 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2028 horizontal and vertical chroma subsample values. For example for the
2029 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2032 If the input image format is different from the format requested by
2033 the next filter, the scale filter will convert the input to the
2036 If the value for @var{w} or @var{h} is 0, the respective input
2037 size is used for the output.
2039 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
2040 respective output size, a value that maintains the aspect ratio of the input
2043 The default value of @var{w} and @var{h} is 0.
2045 Some examples follow:
2047 # scale the input video to a size of 200x100.
2050 # scale the input to 2x
2052 # the above is the same as
2055 # scale the input to half size
2058 # increase the width, and set the height to the same size
2061 # seek for Greek harmony
2065 # increase the height, and set the width to 3/2 of the height
2066 scale=w=3/2*oh:h=3/5*ih
2068 # increase the size, but make the size a multiple of the chroma
2069 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2071 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2072 scale=w='min(500\, iw*3/2):h=-1'
2076 Select frames to pass in output.
2078 This filter accepts the following options:
2083 An expression, which is evaluated for each input frame. If the expression is
2084 evaluated to a non-zero value, the frame is selected and passed to the output,
2085 otherwise it is discarded.
2089 The expression can contain the following constants:
2102 the sequential number of the filtered frame, starting from 0
2105 the sequential number of the selected frame, starting from 0
2107 @item prev_selected_n
2108 the sequential number of the last selected frame, NAN if undefined
2111 timebase of the input timestamps
2114 the PTS (Presentation TimeStamp) of the filtered video frame,
2115 expressed in @var{TB} units, NAN if undefined
2118 the PTS (Presentation TimeStamp) of the filtered video frame,
2119 expressed in seconds, NAN if undefined
2122 the PTS of the previously filtered video frame, NAN if undefined
2124 @item prev_selected_pts
2125 the PTS of the last previously filtered video frame, NAN if undefined
2127 @item prev_selected_t
2128 the PTS of the last previously selected video frame, NAN if undefined
2131 the PTS of the first video frame in the video, NAN if undefined
2134 the time of the first video frame in the video, NAN if undefined
2137 the type of the filtered frame, can assume one of the following
2149 @item interlace_type
2150 the frame interlace type, can assume one of the following values:
2153 the frame is progressive (not interlaced)
2155 the frame is top-field-first
2157 the frame is bottom-field-first
2161 1 if the filtered frame is a key-frame, 0 otherwise
2165 The default value of the select expression is "1".
2167 Some examples follow:
2170 # select all frames in input
2173 # the above is the same as:
2179 # select only I-frames
2180 select='expr=eq(pict_type\,I)'
2182 # select one frame every 100
2183 select='not(mod(n\,100))'
2185 # select only frames contained in the 10-20 time interval
2186 select='gte(t\,10)*lte(t\,20)'
2188 # select only I frames contained in the 10-20 time interval
2189 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2191 # select frames with a minimum distance of 10 seconds
2192 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2198 Set the Display Aspect Ratio for the filter output video.
2200 This is done by changing the specified Sample (aka Pixel) Aspect
2201 Ratio, according to the following equation:
2202 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2204 Keep in mind that this filter does not modify the pixel dimensions of
2205 the video frame. Also the display aspect ratio set by this filter may
2206 be changed by later filters in the filterchain, e.g. in case of
2207 scaling or if another "setdar" or a "setsar" filter is applied.
2209 This filter accepts the following options:
2214 Output display aspect ratio.
2218 The parameter @var{dar} is an expression containing
2219 the following constants:
2223 the corresponding mathematical approximated values for e
2224 (euler number), pi (greek PI), phi (golden ratio)
2227 the input width and height
2230 same as @var{w} / @var{h}
2233 input sample aspect ratio
2236 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2239 horizontal and vertical chroma subsample values. For example for the
2240 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2243 For example to change the display aspect ratio to 16:9, specify:
2246 # the above is equivalent to
2250 See also the @ref{setsar} filter documentation.
2254 Change the PTS (presentation timestamp) of the input video frames.
2256 This filter accepts the following options:
2261 The expression which is evaluated for each frame to construct its timestamp.
2265 The expression is evaluated through the eval API and can contain the following
2270 the presentation timestamp in input
2282 the count of the input frame, starting from 0.
2285 the PTS of the first video frame
2288 tell if the current frame is interlaced
2297 wallclock (RTC) time in microseconds
2300 wallclock (RTC) time at the start of the movie in microseconds
2303 timebase of the input timestamps
2307 Some examples follow:
2310 # start counting PTS from zero
2311 setpts=expr=PTS-STARTPTS
2322 # fixed rate 25 fps with some jitter
2323 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2325 # generate timestamps from a "live source" and rebase onto the current timebase
2326 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
2332 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2334 Note that as a consequence of the application of this filter, the
2335 output display aspect ratio will change according to the following
2337 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2339 Keep in mind that the sample aspect ratio set by this filter may be
2340 changed by later filters in the filterchain, e.g. if another "setsar"
2341 or a "setdar" filter is applied.
2343 This filter accepts the following options:
2348 Output sample aspect ratio.
2352 The parameter @var{sar} is an expression containing
2353 the following constants:
2357 the corresponding mathematical approximated values for e
2358 (euler number), pi (greek PI), phi (golden ratio)
2361 the input width and height
2364 same as @var{w} / @var{h}
2367 input sample aspect ratio
2370 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2373 horizontal and vertical chroma subsample values. For example for the
2374 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2377 For example to change the sample aspect ratio to 10:11, specify:
2384 Set the timebase to use for the output frames timestamps.
2385 It is mainly useful for testing timebase configuration.
2387 This filter accepts the following options:
2392 The expression which is evaluated into the output timebase.
2396 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
2397 default timebase), and "intb" (the input timebase).
2399 The default value for the input is "intb".
2401 Follow some examples.
2404 # set the timebase to 1/25
2407 # set the timebase to 1/10
2410 #set the timebase to 1001/1000
2413 #set the timebase to 2*intb
2416 #set the default timebase value
2422 Show a line containing various information for each input video frame.
2423 The input video is not modified.
2425 The shown line contains a sequence of key/value pairs of the form
2426 @var{key}:@var{value}.
2428 A description of each shown parameter follows:
2432 sequential number of the input frame, starting from 0
2435 Presentation TimeStamp of the input frame, expressed as a number of
2436 time base units. The time base unit depends on the filter input pad.
2439 Presentation TimeStamp of the input frame, expressed as a number of
2443 position of the frame in the input stream, -1 if this information in
2444 unavailable and/or meaningless (for example in case of synthetic video)
2450 sample aspect ratio of the input frame, expressed in the form
2454 size of the input frame, expressed in the form
2455 @var{width}x@var{height}
2458 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2459 for bottom field first)
2462 1 if the frame is a key frame, 0 otherwise
2465 picture type of the input frame ("I" for an I-frame, "P" for a
2466 P-frame, "B" for a B-frame, "?" for unknown type).
2467 Check also the documentation of the @code{AVPictureType} enum and of
2468 the @code{av_get_picture_type_char} function defined in
2469 @file{libavutil/avutil.h}.
2472 Adler-32 checksum of all the planes of the input frame
2474 @item plane_checksum
2475 Adler-32 checksum of each plane of the input frame, expressed in the form
2476 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2479 @section shuffleplanes
2481 Reorder and/or duplicate video planes.
2483 This filter accepts the following options:
2488 The index of the input plane to be used as the first output plane.
2491 The index of the input plane to be used as the second output plane.
2494 The index of the input plane to be used as the third output plane.
2497 The index of the input plane to be used as the fourth output plane.
2501 The first plane has the index 0. The default is to keep the input unchanged.
2505 avconv -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
2507 swaps the second and third planes of the input.
2511 Split input video into several identical outputs.
2513 The filter accepts a single parameter which specifies the number of outputs. If
2514 unspecified, it defaults to 2.
2518 avconv -i INPUT -filter_complex split=5 OUTPUT
2520 will create 5 copies of the input video.
2524 Transpose rows with columns in the input video and optionally flip it.
2526 This filter accepts the following options:
2531 The direction of the transpose.
2535 The direction can assume the following values:
2539 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2547 Rotate by 90 degrees clockwise, that is:
2555 Rotate by 90 degrees counterclockwise, that is:
2563 Rotate by 90 degrees clockwise and vertically flip, that is:
2572 Trim the input so that the output contains one continuous subpart of the input.
2574 This filter accepts the following options:
2577 Timestamp (in seconds) of the start of the kept section. I.e. the frame with the
2578 timestamp @var{start} will be the first frame in the output.
2581 Timestamp (in seconds) of the first frame that will be dropped. I.e. the frame
2582 immediately preceding the one with the timestamp @var{end} will be the last
2583 frame in the output.
2586 Same as @var{start}, except this option sets the start timestamp in timebase
2587 units instead of seconds.
2590 Same as @var{end}, except this option sets the end timestamp in timebase units
2594 Maximum duration of the output in seconds.
2597 Number of the first frame that should be passed to output.
2600 Number of the first frame that should be dropped.
2603 Note that the first two sets of the start/end options and the @option{duration}
2604 option look at the frame timestamp, while the _frame variants simply count the
2605 frames that pass through the filter. Also note that this filter does not modify
2606 the timestamps. If you wish that the output timestamps start at zero, insert a
2607 setpts filter after the trim filter.
2609 If multiple start or end options are set, this filter tries to be greedy and
2610 keep all the frames that match at least one of the specified constraints. To keep
2611 only the part that matches all the constraints at once, chain multiple trim
2614 The defaults are such that all the input is kept. So it is possible to set e.g.
2615 just the end values to keep everything before the specified time.
2620 drop everything except the second minute of input
2622 avconv -i INPUT -vf trim=60:120
2626 keep only the first second
2628 avconv -i INPUT -vf trim=duration=1
2634 Sharpen or blur the input video.
2636 It accepts the following parameters:
2641 Set the luma matrix horizontal size. It can be an integer between 3
2642 and 13, default value is 5.
2645 Set the luma matrix vertical size. It can be an integer between 3
2646 and 13, default value is 5.
2649 Set the luma effect strength. It can be a float number between -2.0
2650 and 5.0, default value is 1.0.
2652 @item chroma_msize_x
2653 Set the chroma matrix horizontal size. It can be an integer between 3
2654 and 13, default value is 5.
2656 @item chroma_msize_y
2657 Set the chroma matrix vertical size. It can be an integer between 3
2658 and 13, default value is 5.
2661 Set the chroma effect strength. It can be a float number between -2.0
2662 and 5.0, default value is 0.0.
2666 Negative values for the amount will blur the input video, while positive
2667 values will sharpen. All parameters are optional and default to the
2668 equivalent of the string '5:5:1.0:5:5:0.0'.
2671 # Strong luma sharpen effect parameters
2672 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
2674 # Strong blur of both luma and chroma parameters
2675 unsharp=7:7:-2:7:7:-2
2677 # Use the default values with @command{avconv}
2678 ./avconv -i in.avi -vf "unsharp" out.mp4
2683 Flip the input video vertically.
2686 ./avconv -i in.avi -vf "vflip" out.avi
2691 Deinterlace the input video ("yadif" means "yet another deinterlacing
2694 This filter accepts the following options:
2699 The interlacing mode to adopt, accepts one of the following values:
2703 output 1 frame for each frame
2705 output 1 frame for each field
2707 like 0 but skips spatial interlacing check
2709 like 1 but skips spatial interlacing check
2715 The picture field parity assumed for the input interlaced video, accepts one of
2716 the following values:
2720 assume top field first
2722 assume bottom field first
2724 enable automatic detection
2727 Default value is -1.
2728 If interlacing is unknown or decoder does not export this information,
2729 top field first will be assumed.
2732 Whether deinterlacer should trust the interlaced flag and only deinterlace
2733 frames marked as interlaced
2737 deinterlace all frames
2739 only deinterlace frames marked as interlaced
2746 @c man end VIDEO FILTERS
2748 @chapter Video Sources
2749 @c man begin VIDEO SOURCES
2751 Below is a description of the currently available video sources.
2755 Buffer video frames, and make them available to the filter chain.
2757 This source is mainly intended for a programmatic use, in particular
2758 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2760 This filter accepts the following parameters:
2771 Name of the input video pixel format.
2774 The time base used for input timestamps.
2777 Sample (pixel) aspect ratio of the input video.
2783 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
2786 will instruct the source to accept video frames with size 320x240 and
2787 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2788 square pixels (1:1 sample aspect ratio).
2792 Provide an uniformly colored input.
2794 It accepts the following parameters:
2799 Specify the color of the source. It can be the name of a color (case
2800 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2801 alpha specifier. The default value is "black".
2804 Specify the size of the sourced video, it may be a string of the form
2805 @var{width}x@var{height}, or the name of a size abbreviation. The
2806 default value is "320x240".
2809 Specify the frame rate of the sourced video, as the number of frames
2810 generated per second. It has to be a string in the format
2811 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2812 number or a valid video frame rate abbreviation. The default value is
2817 For example the following graph description will generate a red source
2818 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2819 frames per second, which will be overlayed over the source connected
2820 to the pad with identifier "in".
2823 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2828 Read a video stream from a movie container.
2830 Note that this source is a hack that bypasses the standard input path. It can be
2831 useful in applications that do not support arbitrary filter graphs, but its use
2832 is discouraged in those that do. Specifically in @command{avconv} this filter
2833 should never be used, the @option{-filter_complex} option fully replaces it.
2835 This filter accepts the following options:
2840 The name of the resource to read (not necessarily a file but also a device or a
2841 stream accessed through some protocol).
2843 @item format_name, f
2844 Specifies the format assumed for the movie to read, and can be either
2845 the name of a container or an input device. If not specified the
2846 format is guessed from @var{movie_name} or by probing.
2848 @item seek_point, sp
2849 Specifies the seek point in seconds, the frames will be output
2850 starting from this seek point, the parameter is evaluated with
2851 @code{av_strtod} so the numerical value may be suffixed by an IS
2852 postfix. Default value is "0".
2854 @item stream_index, si
2855 Specifies the index of the video stream to read. If the value is -1,
2856 the best suited video stream will be automatically selected. Default
2861 This filter allows to overlay a second video on top of main input of
2862 a filtergraph as shown in this graph:
2864 input -----------> deltapts0 --> overlay --> output
2867 movie --> scale--> deltapts1 -------+
2870 Some examples follow:
2872 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2873 # on top of the input labelled as "in".
2874 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2875 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2877 # read from a video4linux2 device, and overlay it on top of the input
2879 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2880 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2886 Null video source, never return images. It is mainly useful as a
2887 template and to be employed in analysis / debugging tools.
2889 It accepts as optional parameter a string of the form
2890 @var{width}:@var{height}:@var{timebase}.
2892 @var{width} and @var{height} specify the size of the configured
2893 source. The default values of @var{width} and @var{height} are
2894 respectively 352 and 288 (corresponding to the CIF size format).
2896 @var{timebase} specifies an arithmetic expression representing a
2897 timebase. The expression can contain the constants "PI", "E", "PHI",
2898 "AVTB" (the default timebase), and defaults to the value "AVTB".
2902 Provide a frei0r source.
2904 To enable compilation of this filter you need to install the frei0r
2905 header and configure Libav with --enable-frei0r.
2907 This source accepts the following options:
2912 The size of the video to generate, may be a string of the form
2913 @var{width}x@var{height} or a frame size abbreviation.
2916 Framerate of the generated video, may be a string of the form
2917 @var{num}/@var{den} or a frame rate abbreviation.
2920 The name to the frei0r source to load. For more information regarding frei0r and
2921 how to set the parameters read the section @ref{frei0r} in the description of
2925 A '|'-separated list of parameters to pass to the frei0r source.
2929 Some examples follow:
2931 # generate a frei0r partik0l source with size 200x200 and framerate 10
2932 # which is overlayed on the overlay filter main input
2933 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
2936 @section rgbtestsrc, testsrc
2938 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2939 detecting RGB vs BGR issues. You should see a red, green and blue
2940 stripe from top to bottom.
2942 The @code{testsrc} source generates a test video pattern, showing a
2943 color pattern, a scrolling gradient and a timestamp. This is mainly
2944 intended for testing purposes.
2946 The sources accept the following options:
2951 Specify the size of the sourced video, it may be a string of the form
2952 @var{width}x@var{height}, or the name of a size abbreviation. The
2953 default value is "320x240".
2956 Specify the frame rate of the sourced video, as the number of frames
2957 generated per second. It has to be a string in the format
2958 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2959 number or a valid video frame rate abbreviation. The default value is
2963 Set the sample aspect ratio of the sourced video.
2966 Set the video duration of the sourced video. The accepted syntax is:
2968 [-]HH[:MM[:SS[.m...]]]
2971 See also the function @code{av_parse_time()}.
2973 If not specified, or the expressed duration is negative, the video is
2974 supposed to be generated forever.
2977 For example the following:
2979 testsrc=duration=5.3:size=qcif:rate=10
2982 will generate a video with a duration of 5.3 seconds, with size
2983 176x144 and a framerate of 10 frames per second.
2985 @c man end VIDEO SOURCES
2987 @chapter Video Sinks
2988 @c man begin VIDEO SINKS
2990 Below is a description of the currently available video sinks.
2994 Buffer video frames, and make them available to the end of the filter
2997 This sink is intended for a programmatic use through the interface defined in
2998 @file{libavfilter/buffersink.h}.
3002 Null video sink, do absolutely nothing with the input video. It is
3003 mainly useful as a template and to be employed in analysis / debugging
3006 @c man end VIDEO SINKS