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 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", and a filter with no
15 output pads is called a "sink".
17 @anchor{Filtergraph syntax}
18 @section Filtergraph syntax
20 A filtergraph has 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()} functions 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 two 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 Here is a BNF description of 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 (possibly 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 It accepts the following 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 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 It accepts the following parameters:
168 The number of inputs. If unspecified, it defaults to 2.
171 How to determine the end-of-stream.
175 The duration of the longest input. (default)
178 The duration of the shortest input.
181 The duration of the first input.
185 @item dropout_transition
186 The 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 It accepts the following parameters:
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
216 These are approximated values for the mathematical constants e
217 (Euler's number), pi (Greek pi), and phi (the golden ratio).
220 The number of audio samples passed through the filter so far, starting at 0.
223 The number of audio samples in the current frame.
226 The audio sample rate.
229 The PTS of the first frame.
232 The previous input PTS.
235 The previous output PTS.
238 The wallclock (RTC) time in microseconds.
241 The wallclock (RTC) time at the start of the movie in microseconds.
248 # Start counting PTS from zero
249 asetpts=expr=PTS-STARTPTS
251 # Generate timestamps by counting samples
254 # Generate timestamps from a "live source" and rebase onto the current timebase
255 asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
260 Set the timebase to use for the output frames timestamps.
261 It is mainly useful for testing timebase configuration.
263 This filter accepts the following parameters:
268 The expression which is evaluated into the output timebase.
272 The expression can contain the constants @var{PI}, @var{E}, @var{PHI}, @var{AVTB} (the
273 default timebase), @var{intb} (the input timebase), and @var{sr} (the sample rate,
276 The default value for the input is @var{intb}.
281 # Set the timebase to 1/25:
284 # Set the timebase to 1/10:
287 # Set the timebase to 1001/1000:
290 # Set the timebase to 2*intb:
293 # Set the default timebase value:
296 # Set the timebase to twice the sample rate:
302 Show a line containing various information for each input audio frame.
303 The input audio is not modified.
305 The shown line contains a sequence of key/value pairs of the form
306 @var{key}:@var{value}.
308 It accepts the following parameters:
312 The (sequential) number of the input frame, starting from 0.
315 The presentation timestamp of the input frame, in time base units; the time base
316 depends on the filter input pad, and is usually 1/@var{sample_rate}.
319 The presentation timestamp of the input frame in seconds.
328 The sample rate for the audio frame.
331 The number of samples (per channel) in the frame.
334 The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar
335 audio, the data is treated as if all the planes were concatenated.
337 @item plane_checksums
338 A list of Adler-32 checksums for each data plane.
343 Split input audio into several identical outputs.
345 It accepts a single parameter, which specifies the number of outputs. If
346 unspecified, it defaults to 2.
350 avconv -i INPUT -filter_complex asplit=5 OUTPUT
352 will create 5 copies of the input audio.
355 Synchronize audio data with timestamps by squeezing/stretching it and/or
356 dropping samples/adding silence when needed.
358 It accepts the following parameters:
362 Enable stretching/squeezing the data to make it match the timestamps. Disabled
363 by default. When disabled, time gaps are covered with silence.
366 The minimum difference between timestamps and audio data (in seconds) to trigger
367 adding/dropping samples. The default value is 0.1. If you get an imperfect
368 sync with this filter, try setting this parameter to 0.
371 The maximum compensation in samples per second. Only relevant with compensate=1.
372 The default value is 500.
375 Assume that the first PTS should be this value. The time base is 1 / sample
376 rate. This allows for padding/trimming at the start of the stream. By default,
377 no assumption is made about the first frame's expected PTS, so no padding or
378 trimming is done. For example, this could be set to 0 to pad the beginning with
379 silence if an audio stream starts after the video stream or to trim any samples
380 with a negative PTS due to encoder delay.
385 Trim the input so that the output contains one continuous subpart of the input.
387 It accepts the following parameters:
390 Timestamp (in seconds) of the start of the section to keep. I.e. the audio
391 sample with the timestamp @var{start} will be the first sample in the output.
394 Timestamp (in seconds) of the first audio sample that will be dropped. I.e. the
395 audio sample immediately preceding the one with the timestamp @var{end} will be
396 the last sample in the output.
399 Same as @var{start}, except this option sets the start timestamp in samples
403 Same as @var{end}, except this option sets the end timestamp in samples instead
407 The maximum duration of the output in seconds.
410 The number of the first sample that should be output.
413 The number of the first sample that should be dropped.
416 Note that the first two sets of the start/end options and the @option{duration}
417 option look at the frame timestamp, while the _sample options simply count the
418 samples that pass through the filter. So start/end_pts and start/end_sample will
419 give different results when the timestamps are wrong, inexact or do not start at
420 zero. Also note that this filter does not modify the timestamps. If you wish
421 to have the output timestamps start at zero, insert the asetpts filter after the
424 If multiple start or end options are set, this filter tries to be greedy and
425 keep all samples that match at least one of the specified constraints. To keep
426 only the part that matches all the constraints at once, chain multiple atrim
429 The defaults are such that all the input is kept. So it is possible to set e.g.
430 just the end values to keep everything before the specified time.
435 Drop everything except the second minute of input:
437 avconv -i INPUT -af atrim=60:120
441 Keep only the first 1000 samples:
443 avconv -i INPUT -af atrim=end_sample=1000
448 @section channelsplit
449 Split each channel from an input audio stream into a separate output stream.
451 It accepts the following parameters:
454 The channel layout of the input stream. The default is "stereo".
457 For example, assuming a stereo input MP3 file,
459 avconv -i in.mp3 -filter_complex channelsplit out.mkv
461 will create an output Matroska file with two audio streams, one containing only
462 the left channel and the other the right channel.
464 Split a 5.1 WAV file into per-channel files:
466 avconv -i in.wav -filter_complex
467 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
468 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
469 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
474 Remap input channels to new locations.
476 It accepts the following parameters:
479 The channel layout of the output stream.
482 Map channels from input to output. The argument is a '|'-separated list of
483 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
484 @var{in_channel} form. @var{in_channel} can be either the name of the input
485 channel (e.g. FL for front left) or its index in the input channel layout.
486 @var{out_channel} is the name of the output channel or its index in the output
487 channel layout. If @var{out_channel} is not given then it is implicitly an
488 index, starting with zero and increasing by one for each mapping.
491 If no mapping is present, the filter will implicitly map input channels to
492 output channels, preserving indices.
494 For example, assuming a 5.1+downmix input MOV file,
496 avconv -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
498 will create an output WAV file tagged as stereo from the downmix channels of
501 To fix a 5.1 WAV improperly encoded in AAC's native channel order
503 avconv -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
507 Compress or expand the audio's dynamic range.
509 It accepts the following parameters:
515 A list of times in seconds for each channel over which the instantaneous level
516 of the input signal is averaged to determine its volume. @var{attacks} refers to
517 increase of volume and @var{decays} refers to decrease of volume. For most
518 situations, the attack time (response to the audio getting louder) should be
519 shorter than the decay time, because the human ear is more sensitive to sudden
520 loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
521 a typical value for decay is 0.8 seconds.
524 A list of points for the transfer function, specified in dB relative to the
525 maximum possible signal amplitude. Each key points list must be defined using
526 the following syntax: @code{x0/y0|x1/y1|x2/y2|....}
528 The input values must be in strictly increasing order but the transfer function
529 does not have to be monotonically rising. The point @code{0/0} is assumed but
530 may be overridden (by @code{0/out-dBn}). Typical values for the transfer
531 function are @code{-70/-70|-60/-20}.
534 Set the curve radius in dB for all joints. It defaults to 0.01.
537 Set the additional gain in dB to be applied at all points on the transfer
538 function. This allows for easy adjustment of the overall gain.
542 Set an initial volume, in dB, to be assumed for each channel when filtering
543 starts. This permits the user to supply a nominal level initially, so that, for
544 example, a very large gain is not applied to initial signal levels before the
545 companding has begun to operate. A typical value for audio which is initially
546 quiet is -90 dB. It defaults to 0.
549 Set a delay, in seconds. The input audio is analyzed immediately, but audio is
550 delayed before being fed to the volume adjuster. Specifying a delay
551 approximately equal to the attack/decay times allows the filter to effectively
552 operate in predictive rather than reactive mode. It defaults to 0.
560 Make music with both quiet and loud passages suitable for listening to in a
563 compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
567 A noise gate for when the noise is at a lower level than the signal:
569 compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
573 Here is another noise gate, this time for when the noise is at a higher level
574 than the signal (making it, in some ways, similar to squelch):
576 compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
581 Join multiple input streams into one multi-channel stream.
583 It accepts the following parameters:
587 The number of input streams. It defaults to 2.
590 The desired output channel layout. It defaults to stereo.
593 Map channels from inputs to output. The argument is a '|'-separated list of
594 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
595 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
596 can be either the name of the input channel (e.g. FL for front left) or its
597 index in the specified input stream. @var{out_channel} is the name of the output
601 The filter will attempt to guess the mappings when they are not specified
602 explicitly. It does so by first trying to find an unused matching input channel
603 and if that fails it picks the first unused input channel.
605 Join 3 inputs (with properly set channel layouts):
607 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
610 Build a 5.1 output from 6 single-channel streams:
612 avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
613 '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'
618 Convert the audio sample format, sample rate and channel layout. It is
619 not meant to be used directly; it is inserted automatically by libavfilter
620 whenever conversion is needed. Use the @var{aformat} filter to force a specific
625 Adjust the input audio volume.
627 It accepts the following parameters:
631 This expresses how the audio volume will be increased or decreased.
633 Output values are clipped to the maximum value.
635 The output audio volume is given by the relation:
637 @var{output_volume} = @var{volume} * @var{input_volume}
640 The default value for @var{volume} is 1.0.
643 This parameter represents the mathematical precision.
645 It determines which input sample formats will be allowed, which affects the
646 precision of the volume scaling.
650 8-bit fixed-point; this limits input sample format to U8, S16, and S32.
652 32-bit floating-point; this limits input sample format to FLT. (default)
654 64-bit floating-point; this limits input sample format to DBL.
658 Choose the behaviour on encountering ReplayGain side data in input frames.
662 Remove ReplayGain side data, ignoring its contents (the default).
665 Ignore ReplayGain side data, but leave it in the frame.
668 Prefer the track gain, if present.
671 Prefer the album gain, if present.
674 @item replaygain_preamp
675 Pre-amplification gain in dB to apply to the selected replaygain gain.
677 Default value for @var{replaygain_preamp} is 0.0.
679 @item replaygain_noclip
680 Prevent clipping by limiting the gain applied.
682 Default value for @var{replaygain_noclip} is 1.
690 Halve the input audio volume:
694 volume=volume=-6.0206dB
698 Increase input audio power by 6 decibels using fixed-point precision:
700 volume=volume=6dB:precision=fixed
704 @c man end AUDIO FILTERS
706 @chapter Audio Sources
707 @c man begin AUDIO SOURCES
709 Below is a description of the currently available audio sources.
713 The null audio source; it never returns audio frames. It is mainly useful as a
714 template and for use in analysis / debugging tools.
716 It accepts, as an optional parameter, a string of the form
717 @var{sample_rate}:@var{channel_layout}.
719 @var{sample_rate} specifies the sample rate, and defaults to 44100.
721 @var{channel_layout} specifies the channel layout, and can be either an
722 integer or a string representing a channel layout. The default value
723 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
725 Check the channel_layout_map definition in
726 @file{libavutil/channel_layout.c} for the mapping between strings and
727 channel layout values.
731 # Set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO
739 Buffer audio frames, and make them available to the filter chain.
741 This source is not intended to be part of user-supplied graph descriptions; it
742 is for insertion by calling programs, through the interface defined in
743 @file{libavfilter/buffersrc.h}.
745 It accepts the following parameters:
749 The timebase which will be used for timestamps of submitted frames. It must be
750 either a floating-point number or in @var{numerator}/@var{denominator} form.
753 The audio sample rate.
756 The name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
759 The channel layout of the audio data, in the form that can be accepted by
760 @code{av_get_channel_layout()}.
763 All the parameters need to be explicitly defined.
765 @c man end AUDIO SOURCES
768 @c man begin AUDIO SINKS
770 Below is a description of the currently available audio sinks.
774 Null audio sink; do absolutely nothing with the input audio. It is
775 mainly useful as a template and for use in analysis / debugging
779 This sink is intended for programmatic use. Frames that arrive on this sink can
780 be retrieved by the calling program, using the interface defined in
781 @file{libavfilter/buffersink.h}.
783 It does not accept any parameters.
785 @c man end AUDIO SINKS
787 @chapter Video Filters
788 @c man begin VIDEO FILTERS
790 When you configure your Libav build, you can disable any of the
791 existing filters using --disable-filters.
792 The configure output will show the video filters included in your
795 Below is a description of the currently available video filters.
799 Detect frames that are (almost) completely black. Can be useful to
800 detect chapter transitions or commercials. Output lines consist of
801 the frame number of the detected frame, the percentage of blackness,
802 the position in the file if known or -1 and the timestamp in seconds.
804 In order to display the output lines, you need to set the loglevel at
805 least to the AV_LOG_INFO value.
807 It accepts the following parameters:
812 The percentage of the pixels that have to be below the threshold; it defaults to
816 The threshold below which a pixel value is considered black; it defaults to 32.
822 Apply a boxblur algorithm to the input video.
824 It accepts the following parameters:
837 The chroma and alpha parameters are optional. If not specified, they default
838 to the corresponding values set for @var{luma_radius} and
841 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
842 the radius in pixels of the box used for blurring the corresponding
843 input plane. They are expressions, and can contain the following
847 The input width and height in pixels.
850 The input chroma image width and height in pixels.
853 The horizontal and vertical chroma subsample values. For example, for the
854 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
857 The radius must be a non-negative number, and must not be greater than
858 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
859 and of @code{min(cw,ch)/2} for the chroma planes.
861 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
862 how many times the boxblur filter is applied to the corresponding
870 Apply a boxblur filter with the luma, chroma, and alpha radii
873 boxblur=luma_radius=2:luma_power=1
877 Set the luma radius to 2, and alpha and chroma radius to 0:
883 Set the luma and chroma radii to a fraction of the video dimension:
885 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
892 Copy the input source unchanged to the output. This is mainly useful for
897 Crop the input video to given dimensions.
899 It accepts the following parameters:
904 The width of the output video.
907 The height of the output video.
910 The horizontal position, in the input video, of the left edge of the output
914 The vertical position, in the input video, of the top edge of the output video.
918 The parameters are expressions containing the following constants:
922 These are approximated values for the mathematical constants e
923 (Euler's number), pi (Greek pi), and phi (the golden ratio).
926 The computed values for @var{x} and @var{y}. They are evaluated for
930 The input width and height.
933 These are the same as @var{in_w} and @var{in_h}.
936 The output (cropped) width and height.
939 These are the same as @var{out_w} and @var{out_h}.
942 The number of the input frame, starting from 0.
945 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
949 The @var{out_w} and @var{out_h} parameters specify the expressions for
950 the width and height of the output (cropped) video. They are only
951 evaluated during the configuration of the filter.
953 The default value of @var{out_w} is "in_w", and the default value of
954 @var{out_h} is "in_h".
956 The expression for @var{out_w} may depend on the value of @var{out_h},
957 and the expression for @var{out_h} may depend on @var{out_w}, but they
958 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
959 evaluated after @var{out_w} and @var{out_h}.
961 The @var{x} and @var{y} parameters specify the expressions for the
962 position of the top-left corner of the output (non-cropped) area. They
963 are evaluated for each frame. If the evaluated value is not valid, it
964 is approximated to the nearest valid value.
966 The default value of @var{x} is "(in_w-out_w)/2", and the default
967 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
968 the center of the input image.
970 The expression for @var{x} may depend on @var{y}, and the expression
971 for @var{y} may depend on @var{x}.
975 # Crop the central input area with size 100x100
976 crop=out_w=100:out_h=100
978 # Crop the central input area with size 2/3 of the input video
979 "crop=out_w=2/3*in_w:out_h=2/3*in_h"
981 # Crop the input video central square
984 # Delimit the rectangle with the top-left corner placed at position
985 # 100:100 and the right-bottom corner corresponding to the right-bottom
986 # corner of the input image
987 crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
989 # Crop 10 pixels from the left and right borders, and 20 pixels from
990 # the top and bottom borders
991 "crop=out_w=in_w-2*10:out_h=in_h-2*20"
993 # Keep only the bottom right quarter of the input image
994 "crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
996 # Crop height for getting Greek harmony
997 "crop=out_w=in_w:out_h=1/PHI*in_w"
1000 "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)"
1002 # Erratic camera effect depending on timestamp
1003 "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)"
1005 # Set x depending on the value of y
1006 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1011 Auto-detect the crop size.
1013 It calculates the necessary cropping parameters and prints the
1014 recommended parameters via the logging system. The detected dimensions
1015 correspond to the non-black area of the input video.
1017 It accepts the following parameters:
1022 The threshold, an optional parameter between nothing (0) and
1023 everything (255). It defaults to 24.
1026 The value which the width/height should be divisible by. It defaults to
1027 16. The offset is automatically adjusted to center the video. Use 2 to
1028 get only even dimensions (needed for 4:2:2 video). 16 is best when
1029 encoding to most video codecs.
1032 A counter that determines how many frames cropdetect will reset
1033 the previously detected largest video area after. It will then start over
1034 and detect the current optimal crop area. It defaults to 0.
1036 This can be useful when channel logos distort the video area. 0
1037 indicates 'never reset', and returns the largest area encountered during
1043 Suppress a TV station logo by a simple interpolation of the surrounding
1044 pixels. Just set a rectangle covering the logo and watch it disappear
1045 (and sometimes something even uglier appear - your mileage may vary).
1047 It accepts the following parameters:
1051 Specify the top left corner coordinates of the logo. They must be
1055 Specify the width and height of the logo to clear. They must be
1059 Specify the thickness of the fuzzy edge of the rectangle (added to
1060 @var{w} and @var{h}). The default value is 4.
1063 When set to 1, a green rectangle is drawn on the screen to simplify
1064 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1065 @var{band} is set to 4. The default value is 0.
1074 Set a rectangle covering the area with top left corner coordinates 0,0
1075 and size 100x77, and a band of size 10:
1077 delogo=x=0:y=0:w=100:h=77:band=10
1084 Draw a colored box on the input image.
1086 It accepts the following parameters:
1091 Specify the top left corner coordinates of the box. It defaults to 0.
1094 Specify the width and height of the box; if 0 they are interpreted as
1095 the input width and height. It defaults to 0.
1098 Specify the color of the box to write. It can be the name of a color
1099 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1104 # Draw a black box around the edge of the input image
1107 # Draw a box with color red and an opacity of 50%
1108 drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
1113 Draw a text string or text from a specified file on top of a video, using the
1114 libfreetype library.
1116 To enable compilation of this filter, you need to configure Libav with
1117 @code{--enable-libfreetype}.
1119 The filter also recognizes strftime() sequences in the provided text
1120 and expands them accordingly. Check the documentation of strftime().
1122 It accepts the following parameters:
1127 The font file to be used for drawing text. The path must be included.
1128 This parameter is mandatory.
1131 The text string to be drawn. The text must be a sequence of UTF-8
1133 This parameter is mandatory if no file is specified with the parameter
1137 A text file containing text to be drawn. The text must be a sequence
1138 of UTF-8 encoded characters.
1140 This parameter is mandatory if no text string is specified with the
1141 parameter @var{text}.
1143 If both text and textfile are specified, an error is thrown.
1146 The offsets where text will be drawn within the video frame.
1147 It is relative to the top/left border of the output image.
1148 They accept expressions similar to the @ref{overlay} filter:
1152 The computed values for @var{x} and @var{y}. They are evaluated for
1155 @item main_w, main_h
1156 The main input width and height.
1159 These are the same as @var{main_w} and @var{main_h}.
1161 @item text_w, text_h
1162 The rendered text's width and height.
1165 These are the same as @var{text_w} and @var{text_h}.
1168 The number of frames processed, starting from 0.
1171 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
1175 The default value of @var{x} and @var{y} is 0.
1178 The font size to be used for drawing text.
1179 The default value of @var{fontsize} is 16.
1182 The color to be used for drawing fonts.
1183 It is either a string (e.g. "red"), or in 0xRRGGBB[AA] format
1184 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1185 The default value of @var{fontcolor} is "black".
1188 The color to be used for drawing box around text.
1189 It is either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1190 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1191 The default value of @var{boxcolor} is "white".
1194 Used to draw a box around text using the background color.
1195 The value must be either 1 (enable) or 0 (disable).
1196 The default value of @var{box} is 0.
1198 @item shadowx, shadowy
1199 The x and y offsets for the text shadow position with respect to the
1200 position of the text. They can be either positive or negative
1201 values. The default value for both is "0".
1204 The color to be used for drawing a shadow behind the drawn text. It
1205 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1206 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1207 The default value of @var{shadowcolor} is "black".
1210 The flags to be used for loading the fonts.
1212 The flags map the corresponding flags supported by libfreetype, and are
1213 a combination of the following values:
1220 @item vertical_layout
1221 @item force_autohint
1224 @item ignore_global_advance_width
1226 @item ignore_transform
1233 Default value is "render".
1235 For more information consult the documentation for the FT_LOAD_*
1239 The size in number of spaces to use for rendering the tab.
1243 If true, check and fix text coords to avoid clipping.
1246 For example the command:
1248 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1251 will draw "Test Text" with font FreeSerif, using the default values
1252 for the optional parameters.
1256 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1257 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1260 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
1261 and y=50 (counting from the top-left corner of the screen), text is
1262 yellow with a red box around it. Both the text and the box have an
1265 Note that the double quotes are not necessary if spaces are not used
1266 within the parameter list.
1268 For more information about libfreetype, check:
1269 @url{http://www.freetype.org/}.
1273 Apply a fade-in/out effect to the input video.
1275 It accepts the following parameters:
1280 The effect type can be either "in" for a fade-in, or "out" for a fade-out
1284 The number of the frame to start applying the fade effect at.
1287 The number of frames that the fade effect lasts. At the end of the
1288 fade-in effect, the output video will have the same intensity as the input video.
1289 At the end of the fade-out transition, the output video will be completely black.
1295 # Fade in the first 30 frames of video
1296 fade=type=in:nb_frames=30
1298 # Fade out the last 45 frames of a 200-frame video
1299 fade=type=out:start_frame=155:nb_frames=45
1301 # Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video
1302 fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
1304 # Make the first 5 frames black, then fade in from frame 5-24
1305 fade=type=in:start_frame=5:nb_frames=20
1310 Transform the field order of the input video.
1312 It accepts the following parameters:
1317 The output field order. Valid values are @var{tff} for top field first or @var{bff}
1318 for bottom field first.
1321 The default value is "tff".
1323 The transformation is done by shifting the picture content up or down
1324 by one line, and filling the remaining line with appropriate picture content.
1325 This method is consistent with most broadcast field order converters.
1327 If the input video is not flagged as being interlaced, or it is already
1328 flagged as being of the required output field order, then this filter does
1329 not alter the incoming video.
1331 It is very useful when converting to or from PAL DV material,
1332 which is bottom field first.
1336 ./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
1341 Buffer input images and send them when they are requested.
1343 It is mainly useful when auto-inserted by the libavfilter
1346 It does not take parameters.
1350 Convert the input video to one of the specified pixel formats.
1351 Libavfilter will try to pick one that is suitable as input to
1354 It accepts the following parameters:
1358 A '|'-separated list of pixel format names, such as
1359 "pix_fmts=yuv420p|monow|rgb24".
1365 # Convert the input video to the "yuv420p" format
1366 format=pix_fmts=yuv420p
1368 # Convert the input video to any of the formats in the list
1369 format=pix_fmts=yuv420p|yuv444p|yuv410p
1375 Convert the video to specified constant framerate by duplicating or dropping
1376 frames as necessary.
1378 It accepts the following parameters:
1382 The desired output framerate.
1385 Assume the first PTS should be the given value, in seconds. This allows for
1386 padding/trimming at the start of stream. By default, no assumption is made
1387 about the first frame's expected PTS, so no padding or trimming is done.
1388 For example, this could be set to 0 to pad the beginning with duplicates of
1389 the first frame if a video stream starts after the audio stream or to trim any
1390 frames with a negative PTS.
1396 Pack two different video streams into a stereoscopic video, setting proper
1397 metadata on supported codecs. The two views should have the same size and
1398 framerate and processing will stop when the shorter video ends. Please note
1399 that you may conveniently adjust view properties with the @ref{scale} and
1402 It accepts the following parameters:
1406 The desired packing format. Supported values are:
1411 The views are next to each other (default).
1414 The views are on top of each other.
1417 The views are packed by line.
1420 The views are packed by column.
1423 The views are temporally interleaved.
1432 # Convert left and right views into a frame-sequential video
1433 avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
1435 # Convert views into a side-by-side video with the same output resolution as the input
1436 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
1442 Apply a frei0r effect to the input video.
1444 To enable the compilation of this filter, you need to install the frei0r
1445 header and configure Libav with --enable-frei0r.
1447 It accepts the following parameters:
1452 The name of the frei0r effect to load. If the environment variable
1453 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
1454 directories specified by the colon-separated list in @env{FREIOR_PATH}.
1455 Otherwise, the standard frei0r paths are searched, in this order:
1456 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
1457 @file{/usr/lib/frei0r-1/}.
1460 A '|'-separated list of parameters to pass to the frei0r effect.
1464 A frei0r effect parameter can be a boolean (its value is either
1465 "y" or "n"), a double, a color (specified as
1466 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
1467 numbers between 0.0 and 1.0, inclusive) or by an @code{av_parse_color()} color
1468 description), a position (specified as @var{X}/@var{Y}, where
1469 @var{X} and @var{Y} are floating point numbers) and/or a string.
1471 The number and types of parameters depend on the loaded effect. If an
1472 effect parameter is not specified, the default value is set.
1476 # Apply the distort0r effect, setting the first two double parameters
1477 frei0r=filter_name=distort0r:filter_params=0.5|0.01
1479 # Apply the colordistance effect, taking a color as the first parameter
1480 frei0r=colordistance:0.2/0.3/0.4
1481 frei0r=colordistance:violet
1482 frei0r=colordistance:0x112233
1484 # Apply the perspective effect, specifying the top left and top right
1486 frei0r=perspective:0.2/0.2|0.8/0.2
1489 For more information, see
1490 @url{http://piksel.org/frei0r}
1494 Fix the banding artifacts that are sometimes introduced into nearly flat
1495 regions by truncation to 8bit colordepth.
1496 Interpolate the gradients that should go where the bands are, and
1499 It is designed for playback only. Do not use it prior to
1500 lossy compression, because compression tends to lose the dither and
1501 bring back the bands.
1503 It accepts the following parameters:
1508 The maximum amount by which the filter will change any one pixel. This is also
1509 the threshold for detecting nearly flat regions. Acceptable values range from
1510 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
1514 The neighborhood to fit the gradient to. A larger radius makes for smoother
1515 gradients, but also prevents the filter from modifying the pixels near detailed
1516 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
1517 values will be clipped to the valid range.
1522 # Default parameters
1523 gradfun=strength=1.2:radius=16
1525 # Omitting the radius
1531 Flip the input video horizontally.
1533 For example, to horizontally flip the input video with @command{avconv}:
1535 avconv -i in.avi -vf "hflip" out.avi
1540 This is a high precision/quality 3d denoise filter. It aims to reduce
1541 image noise, producing smooth images and making still images really
1542 still. It should enhance compressibility.
1544 It accepts the following optional parameters:
1548 A non-negative floating point number which specifies spatial luma strength.
1551 @item chroma_spatial
1552 A non-negative floating point number which specifies spatial chroma strength.
1553 It defaults to 3.0*@var{luma_spatial}/4.0.
1556 A floating point number which specifies luma temporal strength. It defaults to
1557 6.0*@var{luma_spatial}/4.0.
1560 A floating point number which specifies chroma temporal strength. It defaults to
1561 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
1566 Simple interlacing filter from progressive contents. This interleaves upper (or
1567 lower) lines from odd frames with lower (or upper) lines from even frames,
1568 halving the frame rate and preserving image height. A vertical lowpass filter
1569 is always applied in order to avoid twitter effects and reduce moiré patterns.
1572 Original Original New Frame
1573 Frame 'j' Frame 'j+1' (tff)
1574 ========== =========== ==================
1575 Line 0 --------------------> Frame 'j' Line 0
1576 Line 1 Line 1 ----> Frame 'j+1' Line 1
1577 Line 2 ---------------------> Frame 'j' Line 2
1578 Line 3 Line 3 ----> Frame 'j+1' Line 3
1580 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
1583 It accepts the following optional parameters:
1587 This determines whether the interlaced frame is taken from the even
1588 (tff - default) or odd (bff) lines of the progressive frame.
1591 @section lut, lutrgb, lutyuv
1593 Compute a look-up table for binding each pixel component input value
1594 to an output value, and apply it to the input video.
1596 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1597 to an RGB input video.
1599 These filters accept the following parameters:
1601 @item @var{c0} (first pixel component)
1602 @item @var{c1} (second pixel component)
1603 @item @var{c2} (third pixel component)
1604 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
1606 @item @var{r} (red component)
1607 @item @var{g} (green component)
1608 @item @var{b} (blue component)
1609 @item @var{a} (alpha component)
1611 @item @var{y} (Y/luminance component)
1612 @item @var{u} (U/Cb component)
1613 @item @var{v} (V/Cr component)
1616 Each of them specifies the expression to use for computing the lookup table for
1617 the corresponding pixel component values.
1619 The exact component associated to each of the @var{c*} options depends on the
1622 The @var{lut} filter requires either YUV or RGB pixel formats in input,
1623 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
1625 The expressions can contain the following constants and functions:
1629 These are approximated values for the mathematical constants e
1630 (Euler's number), pi (Greek pi), and phi (the golden ratio).
1633 The input width and height.
1636 The input value for the pixel component.
1639 The input value, clipped to the @var{minval}-@var{maxval} range.
1642 The maximum value for the pixel component.
1645 The minimum value for the pixel component.
1648 The negated value for the pixel component value, clipped to the
1649 @var{minval}-@var{maxval} range; it corresponds to the expression
1650 "maxval-clipval+minval".
1653 The computed value in @var{val}, clipped to the
1654 @var{minval}-@var{maxval} range.
1656 @item gammaval(gamma)
1657 The computed gamma correction value of the pixel component value,
1658 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
1660 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1664 All expressions default to "val".
1668 # Negate input video
1669 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1670 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1672 # The above is the same as
1673 lutrgb="r=negval:g=negval:b=negval"
1674 lutyuv="y=negval:u=negval:v=negval"
1679 # Remove chroma components, turning the video into a graytone image
1680 lutyuv="u=128:v=128"
1682 # Apply a luma burning effect
1685 # Remove green and blue components
1688 # Set a constant alpha channel value on input
1689 format=rgba,lutrgb=a="maxval-minval/2"
1691 # Correct luminance gamma by a factor of 0.5
1692 lutyuv=y=gammaval(0.5)
1699 It accepts an integer in input; if non-zero it negates the
1700 alpha component (if available). The default value in input is 0.
1704 Force libavfilter not to use any of the specified pixel formats for the
1705 input to the next filter.
1707 It accepts the following parameters:
1711 A '|'-separated list of pixel format names, such as
1712 apix_fmts=yuv420p|monow|rgb24".
1718 # Force libavfilter to use a format different from "yuv420p" for the
1719 # input to the vflip filter
1720 noformat=pix_fmts=yuv420p,vflip
1722 # Convert the input video to any of the formats not contained in the list
1723 noformat=yuv420p|yuv444p|yuv410p
1728 Pass the video source unchanged to the output.
1732 Apply a video transform using libopencv.
1734 To enable this filter, install the libopencv library and headers and
1735 configure Libav with --enable-libopencv.
1737 It accepts the following parameters:
1742 The name of the libopencv filter to apply.
1745 The parameters to pass to the libopencv filter. If not specified, the default
1750 Refer to the official libopencv documentation for more precise
1752 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1754 Several libopencv filters are supported; see the following subsections.
1759 Dilate an image by using a specific structuring element.
1760 It corresponds to the libopencv function @code{cvDilate}.
1762 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
1764 @var{struct_el} represents a structuring element, and has the syntax:
1765 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1767 @var{cols} and @var{rows} represent the number of columns and rows of
1768 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1769 point, and @var{shape} the shape for the structuring element. @var{shape}
1770 must be "rect", "cross", "ellipse", or "custom".
1772 If the value for @var{shape} is "custom", it must be followed by a
1773 string of the form "=@var{filename}". The file with name
1774 @var{filename} is assumed to represent a binary image, with each
1775 printable character corresponding to a bright pixel. When a custom
1776 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1777 or columns and rows of the read file are assumed instead.
1779 The default value for @var{struct_el} is "3x3+0x0/rect".
1781 @var{nb_iterations} specifies the number of times the transform is
1782 applied to the image, and defaults to 1.
1786 # Use the default values
1789 # Dilate using a structuring element with a 5x5 cross, iterating two times
1790 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
1792 # Read the shape from the file diamond.shape, iterating two times.
1793 # The file diamond.shape may contain a pattern of characters like this
1799 # The specified columns and rows are ignored
1800 # but the anchor point coordinates are not
1801 ocv=dilate:0x0+2x2/custom=diamond.shape|2
1806 Erode an image by using a specific structuring element.
1807 It corresponds to the libopencv function @code{cvErode}.
1809 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
1810 with the same syntax and semantics as the @ref{dilate} filter.
1814 Smooth the input video.
1816 The filter takes the following parameters:
1817 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
1819 @var{type} is the type of smooth filter to apply, and must be one of
1820 the following values: "blur", "blur_no_scale", "median", "gaussian",
1821 or "bilateral". The default value is "gaussian".
1823 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
1824 depend on the smooth type. @var{param1} and
1825 @var{param2} accept integer positive values or 0. @var{param3} and
1826 @var{param4} accept floating point values.
1828 The default value for @var{param1} is 3. The default value for the
1829 other parameters is 0.
1831 These parameters correspond to the parameters assigned to the
1832 libopencv function @code{cvSmooth}.
1837 Overlay one video on top of another.
1839 It takes two inputs and has one output. The first input is the "main"
1840 video on which the second input is overlayed.
1842 It accepts the following parameters:
1847 The horizontal position of the left edge of the overlaid video on the main video.
1850 The vertical position of the top edge of the overlaid video on the main video.
1854 The parameters are expressions containing the following parameters:
1857 @item main_w, main_h
1858 The main input width and height.
1861 These are the same as @var{main_w} and @var{main_h}.
1863 @item overlay_w, overlay_h
1864 The overlay input width and height.
1867 These are the same as @var{overlay_w} and @var{overlay_h}.
1870 The action to take when EOF is encountered on the secondary input; it accepts
1871 one of the following values:
1875 Repeat the last frame (the default).
1879 Pass the main input through.
1884 Be aware that frames are taken from each input video in timestamp
1885 order, hence, if their initial timestamps differ, it is a a good idea
1886 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1887 have them begin in the same zero timestamp, as the example for
1888 the @var{movie} filter does.
1892 # Draw the overlay at 10 pixels from the bottom right
1893 # corner of the main video
1894 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
1896 # Insert a transparent PNG logo in the bottom left corner of the input
1897 avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
1899 # Insert 2 different transparent PNG logos (second logo on bottom
1901 avconv -i input -i logo1 -i logo2 -filter_complex
1902 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
1904 # Add a transparent color layer on top of the main video;
1905 # WxH specifies the size of the main input to the overlay filter
1906 color=red@.3:WxH [over]; [in][over] overlay [out]
1908 # Mask 10-20 seconds of a video by applying the delogo filter to a section
1909 avconv -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
1910 -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]'
1914 You can chain together more overlays but the efficiency of such
1915 approach is yet to be tested.
1919 Add paddings to the input image, and place the original input at the
1920 provided @var{x}, @var{y} coordinates.
1922 It accepts the following parameters:
1927 Specify the size of the output image with the paddings added. If the
1928 value for @var{width} or @var{height} is 0, the corresponding input size
1929 is used for the output.
1931 The @var{width} expression can reference the value set by the
1932 @var{height} expression, and vice versa.
1934 The default value of @var{width} and @var{height} is 0.
1938 Specify the offsets to place the input image at within the padded area,
1939 with respect to the top/left border of the output image.
1941 The @var{x} expression can reference the value set by the @var{y}
1942 expression, and vice versa.
1944 The default value of @var{x} and @var{y} is 0.
1948 Specify the color of the padded area. It can be the name of a color
1949 (case insensitive match) or an 0xRRGGBB[AA] sequence.
1951 The default value of @var{color} is "black".
1955 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1956 expressions containing the following constants:
1960 These are approximated values for the mathematical constants e
1961 (Euler's number), pi (Greek pi), and phi (the golden ratio).
1964 The input video width and height.
1967 These are the same as @var{in_w} and @var{in_h}.
1970 The output width and height (the size of the padded area), as
1971 specified by the @var{width} and @var{height} expressions.
1974 These are the same as @var{out_w} and @var{out_h}.
1977 The x and y offsets as specified by the @var{x} and @var{y}
1978 expressions, or NAN if not yet specified.
1981 The input display aspect ratio, same as @var{iw} / @var{ih}.
1984 The horizontal and vertical chroma subsample values. For example for the
1985 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1991 # Add paddings with the color "violet" to the input video. The output video
1992 # size is 640x480, and the top-left corner of the input video is placed at
1994 pad=width=640:height=480:x=0:y=40:color=violet
1996 # Pad the input to get an output with dimensions increased by 3/2,
1997 # and put the input video at the center of the padded area
1998 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2000 # Pad the input to get a squared output with size equal to the maximum
2001 # value between the input width and height, and put the input video at
2002 # the center of the padded area
2003 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2005 # Pad the input to get a final w/h ratio of 16:9
2006 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2008 # Double the output size and put the input video in the bottom-right
2009 # corner of the output padded area
2010 pad="2*iw:2*ih:ow-iw:oh-ih"
2013 @section pixdesctest
2015 Pixel format descriptor test filter, mainly useful for internal
2016 testing. The output video should be equal to the input video.
2020 format=monow, pixdesctest
2023 can be used to test the monowhite pixel format descriptor definition.
2028 Scale the input video and/or convert the image format.
2030 It accepts the following parameters:
2035 The output video width.
2038 The output video height.
2042 The parameters @var{w} and @var{h} are expressions containing
2043 the following constants:
2047 These are approximated values for the mathematical constants e
2048 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2051 The input width and height.
2054 These are the same as @var{in_w} and @var{in_h}.
2057 The output (cropped) width and height.
2060 These are the same as @var{out_w} and @var{out_h}.
2063 This is the same as @var{iw} / @var{ih}.
2066 input sample aspect ratio
2069 The input display aspect ratio; it is the same as
2070 (@var{iw} / @var{ih}) * @var{sar}.
2073 The horizontal and vertical chroma subsample values. For example, for the
2074 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2077 If the input image format is different from the format requested by
2078 the next filter, the scale filter will convert the input to the
2081 If the value for @var{w} or @var{h} is 0, the respective input
2082 size is used for the output.
2084 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
2085 respective output size, a value that maintains the aspect ratio of the input
2088 The default value of @var{w} and @var{h} is 0.
2092 # Scale the input video to a size of 200x100
2095 # Scale the input to 2x
2097 # The above is the same as
2100 # Scale the input to half the original size
2103 # Increase the width, and set the height to the same size
2106 # Seek Greek harmony
2110 # Increase the height, and set the width to 3/2 of the height
2111 scale=w=3/2*oh:h=3/5*ih
2113 # Increase the size, making the size a multiple of the chroma
2114 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2116 # Increase the width to a maximum of 500 pixels,
2117 # keeping the same aspect ratio as the input
2118 scale=w='min(500\, iw*3/2):h=-1'
2122 Select frames to pass in output.
2124 It accepts the following parameters:
2129 An expression, which is evaluated for each input frame. If the expression is
2130 evaluated to a non-zero value, the frame is selected and passed to the output,
2131 otherwise it is discarded.
2135 The expression can contain the following constants:
2139 These are approximated values for the mathematical constants e
2140 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2143 The (sequential) number of the filtered frame, starting from 0.
2146 The (sequential) number of the selected frame, starting from 0.
2148 @item prev_selected_n
2149 The sequential number of the last selected frame. It's NAN if undefined.
2152 The timebase of the input timestamps.
2155 The PTS (Presentation TimeStamp) of the filtered video frame,
2156 expressed in @var{TB} units. It's NAN if undefined.
2159 The PTS of the filtered video frame,
2160 expressed in seconds. It's NAN if undefined.
2163 The PTS of the previously filtered video frame. It's NAN if undefined.
2165 @item prev_selected_pts
2166 The PTS of the last previously filtered video frame. It's NAN if undefined.
2168 @item prev_selected_t
2169 The PTS of the last previously selected video frame. It's NAN if undefined.
2172 The PTS of the first video frame in the video. It's NAN if undefined.
2175 The time of the first video frame in the video. It's NAN if undefined.
2178 The type of the filtered frame. It can assume one of the following
2190 @item interlace_type
2191 The frame interlace type. It can assume one of the following values:
2194 The frame is progressive (not interlaced).
2196 The frame is top-field-first.
2198 The frame is bottom-field-first.
2202 This is 1 if the filtered frame is a key-frame, 0 otherwise.
2206 The default value of the select expression is "1".
2211 # Select all the frames in input
2214 # The above is the same as
2220 # Select only I-frames
2221 select='expr=eq(pict_type\,I)'
2223 # Select one frame per 100
2224 select='not(mod(n\,100))'
2226 # Select only frames contained in the 10-20 time interval
2227 select='gte(t\,10)*lte(t\,20)'
2229 # Select only I frames contained in the 10-20 time interval
2230 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2232 # Select frames with a minimum distance of 10 seconds
2233 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2239 Set the Display Aspect Ratio for the filter output video.
2241 This is done by changing the specified Sample (aka Pixel) Aspect
2242 Ratio, according to the following equation:
2243 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2245 Keep in mind that this filter does not modify the pixel dimensions of
2246 the video frame. Also, the display aspect ratio set by this filter may
2247 be changed by later filters in the filterchain, e.g. in case of
2248 scaling or if another "setdar" or a "setsar" filter is applied.
2250 It accepts the following parameters:
2255 The output display aspect ratio.
2259 The parameter @var{dar} is an expression containing
2260 the following constants:
2264 These are approximated values for the mathematical constants e
2265 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2268 The input width and height.
2271 This is the same as @var{w} / @var{h}.
2274 The input sample aspect ratio.
2277 The input display aspect ratio. It is the same as
2278 (@var{w} / @var{h}) * @var{sar}.
2281 The horizontal and vertical chroma subsample values. For example, for the
2282 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2285 To change the display aspect ratio to 16:9, specify:
2288 # The above is equivalent to
2292 Also see the the @ref{setsar} filter documentation.
2296 Change the PTS (presentation timestamp) of the input video frames.
2298 It accepts the following parameters:
2303 The expression which is evaluated for each frame to construct its timestamp.
2307 The expression is evaluated through the eval API and can contain the following
2312 The presentation timestamp in input.
2315 These are approximated values for the mathematical constants e
2316 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2319 The count of the input frame, starting from 0.
2322 The PTS of the first video frame.
2325 State whether the current frame is interlaced.
2328 The previous input PTS.
2331 The previous output PTS.
2334 The wallclock (RTC) time in microseconds.
2337 The wallclock (RTC) time at the start of the movie in microseconds.
2340 The timebase of the input timestamps.
2347 # Start counting the PTS from zero
2348 setpts=expr=PTS-STARTPTS
2359 # Fixed rate 25 fps with some jitter
2360 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2362 # Generate timestamps from a "live source" and rebase onto the current timebase
2363 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
2369 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2371 Note that as a consequence of the application of this filter, the
2372 output display aspect ratio will change according to the following
2374 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2376 Keep in mind that the sample aspect ratio set by this filter may be
2377 changed by later filters in the filterchain, e.g. if another "setsar"
2378 or a "setdar" filter is applied.
2380 It accepts the following parameters:
2385 The output sample aspect ratio.
2389 The parameter @var{sar} is an expression containing
2390 the following constants:
2394 These are approximated values for the mathematical constants e
2395 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2398 The input width and height.
2401 These are the same as @var{w} / @var{h}.
2404 The input sample aspect ratio.
2407 The input display aspect ratio. It is the same as
2408 (@var{w} / @var{h}) * @var{sar}.
2411 Horizontal and vertical chroma subsample values. For example, for the
2412 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2415 To change the sample aspect ratio to 10:11, specify:
2422 Set the timebase to use for the output frames timestamps.
2423 It is mainly useful for testing timebase configuration.
2425 It accepts the following parameters:
2430 The expression which is evaluated into the output timebase.
2434 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
2435 default timebase), and "intb" (the input timebase).
2437 The default value for the input is "intb".
2442 # Set the timebase to 1/25
2445 # Set the timebase to 1/10
2448 # Set the timebase to 1001/1000
2451 #Set the timebase to 2*intb
2454 #Set the default timebase value
2460 Show a line containing various information for each input video frame.
2461 The input video is not modified.
2463 The shown line contains a sequence of key/value pairs of the form
2464 @var{key}:@var{value}.
2466 It accepts the following parameters:
2470 The (sequential) number of the input frame, starting from 0.
2473 The Presentation TimeStamp of the input frame, expressed as a number of
2474 time base units. The time base unit depends on the filter input pad.
2477 The Presentation TimeStamp of the input frame, expressed as a number of
2481 The position of the frame in the input stream, or -1 if this information is
2482 unavailable and/or meaningless (for example in case of synthetic video).
2485 The pixel format name.
2488 The sample aspect ratio of the input frame, expressed in the form
2489 @var{num}/@var{den}.
2492 The size of the input frame, expressed in the form
2493 @var{width}x@var{height}.
2496 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
2497 for bottom field first).
2500 This is 1 if the frame is a key frame, 0 otherwise.
2503 The picture type of the input frame ("I" for an I-frame, "P" for a
2504 P-frame, "B" for a B-frame, or "?" for an unknown type).
2505 Also refer to the documentation of the @code{AVPictureType} enum and of
2506 the @code{av_get_picture_type_char} function defined in
2507 @file{libavutil/avutil.h}.
2510 The Adler-32 checksum of all the planes of the input frame.
2512 @item plane_checksum
2513 The Adler-32 checksum of each plane of the input frame, expressed in the form
2514 "[@var{c0} @var{c1} @var{c2} @var{c3}]".
2517 @section shuffleplanes
2519 Reorder and/or duplicate video planes.
2521 It accepts the following parameters:
2526 The index of the input plane to be used as the first output plane.
2529 The index of the input plane to be used as the second output plane.
2532 The index of the input plane to be used as the third output plane.
2535 The index of the input plane to be used as the fourth output plane.
2539 The first plane has the index 0. The default is to keep the input unchanged.
2541 Swap the second and third planes of the input:
2543 avconv -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
2548 Split input video into several identical outputs.
2550 It accepts a single parameter, which specifies the number of outputs. If
2551 unspecified, it defaults to 2.
2553 Create 5 copies of the input video:
2555 avconv -i INPUT -filter_complex split=5 OUTPUT
2560 Transpose rows with columns in the input video and optionally flip it.
2562 It accepts the following parameters:
2567 The direction of the transpose.
2571 The direction can assume the following values:
2575 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2583 Rotate by 90 degrees clockwise, that is:
2591 Rotate by 90 degrees counterclockwise, that is:
2599 Rotate by 90 degrees clockwise and vertically flip, that is:
2608 Trim the input so that the output contains one continuous subpart of the input.
2610 It accepts the following parameters:
2613 The timestamp (in seconds) of the start of the kept section. The frame with the
2614 timestamp @var{start} will be the first frame in the output.
2617 The timestamp (in seconds) of the first frame that will be dropped. The frame
2618 immediately preceding the one with the timestamp @var{end} will be the last
2619 frame in the output.
2622 This is the same as @var{start}, except this option sets the start timestamp
2623 in timebase units instead of seconds.
2626 This is the same as @var{end}, except this option sets the end timestamp
2627 in timebase units instead of seconds.
2630 The maximum duration of the output in seconds.
2633 The number of the first frame that should be passed to the output.
2636 The number of the first frame that should be dropped.
2639 Note that the first two sets of the start/end options and the @option{duration}
2640 option look at the frame timestamp, while the _frame variants simply count the
2641 frames that pass through the filter. Also note that this filter does not modify
2642 the timestamps. If you wish for the output timestamps to start at zero, insert a
2643 setpts filter after the trim filter.
2645 If multiple start or end options are set, this filter tries to be greedy and
2646 keep all the frames that match at least one of the specified constraints. To keep
2647 only the part that matches all the constraints at once, chain multiple trim
2650 The defaults are such that all the input is kept. So it is possible to set e.g.
2651 just the end values to keep everything before the specified time.
2656 Drop everything except the second minute of input:
2658 avconv -i INPUT -vf trim=60:120
2662 Keep only the first second:
2664 avconv -i INPUT -vf trim=duration=1
2670 Sharpen or blur the input video.
2672 It accepts the following parameters:
2677 Set the luma matrix horizontal size. It must be an integer between 3
2678 and 13. The default value is 5.
2681 Set the luma matrix vertical size. It must be an integer between 3
2682 and 13. The default value is 5.
2685 Set the luma effect strength. It must be a floating point number between -2.0
2686 and 5.0. The default value is 1.0.
2688 @item chroma_msize_x
2689 Set the chroma matrix horizontal size. It must be an integer between 3
2690 and 13. The default value is 5.
2692 @item chroma_msize_y
2693 Set the chroma matrix vertical size. It must be an integer between 3
2694 and 13. The default value is 5.
2697 Set the chroma effect strength. It must be a floating point number between -2.0
2698 and 5.0. The default value is 0.0.
2702 Negative values for the amount will blur the input video, while positive
2703 values will sharpen. All parameters are optional and default to the
2704 equivalent of the string '5:5:1.0:5:5:0.0'.
2707 # Strong luma sharpen effect parameters
2708 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
2710 # A strong blur of both luma and chroma parameters
2711 unsharp=7:7:-2:7:7:-2
2713 # Use the default values with @command{avconv}
2714 ./avconv -i in.avi -vf "unsharp" out.mp4
2719 Flip the input video vertically.
2722 ./avconv -i in.avi -vf "vflip" out.avi
2727 Deinterlace the input video ("yadif" means "yet another deinterlacing
2730 It accepts the following parameters:
2735 The interlacing mode to adopt. It accepts one of the following values:
2739 Output one frame for each frame.
2741 Output one frame for each field.
2743 Like 0, but it skips the spatial interlacing check.
2745 Like 1, but it skips the spatial interlacing check.
2748 The default value is 0.
2751 The picture field parity assumed for the input interlaced video. It accepts one
2752 of the following values:
2756 Assume the top field is first.
2758 Assume the bottom field is first.
2760 Enable automatic detection of field parity.
2763 The default value is -1.
2764 If the interlacing is unknown or the decoder does not export this information,
2765 top field first will be assumed.
2768 Whether the deinterlacer should trust the interlaced flag and only deinterlace
2769 frames marked as interlaced.
2773 Deinterlace all frames.
2775 Only deinterlace frames marked as interlaced.
2778 The default value is 0.
2782 @c man end VIDEO FILTERS
2784 @chapter Video Sources
2785 @c man begin VIDEO SOURCES
2787 Below is a description of the currently available video sources.
2791 Buffer video frames, and make them available to the filter chain.
2793 This source is mainly intended for a programmatic use, in particular
2794 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2796 It accepts the following parameters:
2801 The input video width.
2804 The input video height.
2807 The name of the input video pixel format.
2810 The time base used for input timestamps.
2813 The sample (pixel) aspect ratio of the input video.
2819 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
2822 will instruct the source to accept video frames with size 320x240 and
2823 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2824 square pixels (1:1 sample aspect ratio).
2828 Provide an uniformly colored input.
2830 It accepts the following parameters:
2835 Specify the color of the source. It can be the name of a color (case
2836 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2837 alpha specifier. The default value is "black".
2840 Specify the size of the sourced video, it may be a string of the form
2841 @var{width}x@var{height}, or the name of a size abbreviation. The
2842 default value is "320x240".
2845 Specify the frame rate of the sourced video, as the number of frames
2846 generated per second. It has to be a string in the format
2847 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
2848 number or a valid video frame rate abbreviation. The default value is
2853 The following graph description will generate a red source
2854 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2855 frames per second, which will be overlayed over the source connected
2856 to the pad with identifier "in":
2859 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2864 Read a video stream from a movie container.
2866 Note that this source is a hack that bypasses the standard input path. It can be
2867 useful in applications that do not support arbitrary filter graphs, but its use
2868 is discouraged in those that do. It should never be used with
2869 @command{avconv}; the @option{-filter_complex} option fully replaces it.
2871 It accepts the following parameters:
2876 The name of the resource to read (not necessarily a file; it can also be a
2877 device or a stream accessed through some protocol).
2879 @item format_name, f
2880 Specifies the format assumed for the movie to read, and can be either
2881 the name of a container or an input device. If not specified, the
2882 format is guessed from @var{movie_name} or by probing.
2884 @item seek_point, sp
2885 Specifies the seek point in seconds. The frames will be output
2886 starting from this seek point. The parameter is evaluated with
2887 @code{av_strtod}, so the numerical value may be suffixed by an IS
2888 postfix. The default value is "0".
2890 @item stream_index, si
2891 Specifies the index of the video stream to read. If the value is -1,
2892 the most suitable video stream will be automatically selected. The default
2897 It allows overlaying a second video on top of the main input of
2898 a filtergraph, as shown in this graph:
2900 input -----------> deltapts0 --> overlay --> output
2903 movie --> scale--> deltapts1 -------+
2908 # Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
2909 # on top of the input labelled "in"
2910 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2911 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2913 # Read from a video4linux2 device, and overlay it on top of the input
2915 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2916 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2922 Null video source: never return images. It is mainly useful as a
2923 template and to be employed in analysis / debugging tools.
2925 It accepts a string of the form
2926 @var{width}:@var{height}:@var{timebase} as an optional parameter.
2928 @var{width} and @var{height} specify the size of the configured
2929 source. The default values of @var{width} and @var{height} are
2930 respectively 352 and 288 (corresponding to the CIF size format).
2932 @var{timebase} specifies an arithmetic expression representing a
2933 timebase. The expression can contain the constants "PI", "E", "PHI", and
2934 "AVTB" (the default timebase), and defaults to the value "AVTB".
2938 Provide a frei0r source.
2940 To enable compilation of this filter you need to install the frei0r
2941 header and configure Libav with --enable-frei0r.
2943 This source accepts the following parameters:
2948 The size of the video to generate. It may be a string of the form
2949 @var{width}x@var{height} or a frame size abbreviation.
2952 The framerate of the generated video. It may be a string of the form
2953 @var{num}/@var{den} or a frame rate abbreviation.
2956 The name to the frei0r source to load. For more information regarding frei0r and
2957 how to set the parameters, read the @ref{frei0r} section in the video filters
2961 A '|'-separated list of parameters to pass to the frei0r source.
2967 # Generate a frei0r partik0l source with size 200x200 and framerate 10
2968 # which is overlayed on the overlay filter main input
2969 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
2972 @section rgbtestsrc, testsrc
2974 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2975 detecting RGB vs BGR issues. You should see a red, green and blue
2976 stripe from top to bottom.
2978 The @code{testsrc} source generates a test video pattern, showing a
2979 color pattern, a scrolling gradient and a timestamp. This is mainly
2980 intended for testing purposes.
2982 The sources accept the following parameters:
2987 Specify the size of the sourced video, it may be a string of the form
2988 @var{width}x@var{height}, or the name of a size abbreviation. The
2989 default value is "320x240".
2992 Specify the frame rate of the sourced video, as the number of frames
2993 generated per second. It has to be a string in the format
2994 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
2995 number or a valid video frame rate abbreviation. The default value is
2999 Set the sample aspect ratio of the sourced video.
3002 Set the video duration of the sourced video. The accepted syntax is:
3004 [-]HH[:MM[:SS[.m...]]]
3007 Also see the the @code{av_parse_time()} function.
3009 If not specified, or the expressed duration is negative, the video is
3010 supposed to be generated forever.
3013 For example the following:
3015 testsrc=duration=5.3:size=qcif:rate=10
3018 will generate a video with a duration of 5.3 seconds, with size
3019 176x144 and a framerate of 10 frames per second.
3021 @c man end VIDEO SOURCES
3023 @chapter Video Sinks
3024 @c man begin VIDEO SINKS
3026 Below is a description of the currently available video sinks.
3030 Buffer video frames, and make them available to the end of the filter
3033 This sink is intended for programmatic use through the interface defined in
3034 @file{libavfilter/buffersink.h}.
3038 Null video sink: do absolutely nothing with the input video. It is
3039 mainly useful as a template and for use in analysis / debugging
3042 @c man end VIDEO SINKS