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.
685 Halve the input audio volume:
689 volume=volume=-6.0206dB
693 Increase input audio power by 6 decibels using fixed-point precision:
695 volume=volume=6dB:precision=fixed
699 @c man end AUDIO FILTERS
701 @chapter Audio Sources
702 @c man begin AUDIO SOURCES
704 Below is a description of the currently available audio sources.
708 The null audio source; it never returns audio frames. It is mainly useful as a
709 template and for use in analysis / debugging tools.
711 It accepts, as an optional parameter, a string of the form
712 @var{sample_rate}:@var{channel_layout}.
714 @var{sample_rate} specifies the sample rate, and defaults to 44100.
716 @var{channel_layout} specifies the channel layout, and can be either an
717 integer or a string representing a channel layout. The default value
718 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
720 Check the channel_layout_map definition in
721 @file{libavutil/channel_layout.c} for the mapping between strings and
722 channel layout values.
726 # Set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO
734 Buffer audio frames, and make them available to the filter chain.
736 This source is not intended to be part of user-supplied graph descriptions; it
737 is for insertion by calling programs, through the interface defined in
738 @file{libavfilter/buffersrc.h}.
740 It accepts the following parameters:
744 The timebase which will be used for timestamps of submitted frames. It must be
745 either a floating-point number or in @var{numerator}/@var{denominator} form.
748 The audio sample rate.
751 The name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
754 The channel layout of the audio data, in the form that can be accepted by
755 @code{av_get_channel_layout()}.
758 All the parameters need to be explicitly defined.
760 @c man end AUDIO SOURCES
763 @c man begin AUDIO SINKS
765 Below is a description of the currently available audio sinks.
769 Null audio sink; do absolutely nothing with the input audio. It is
770 mainly useful as a template and for use in analysis / debugging
774 This sink is intended for programmatic use. Frames that arrive on this sink can
775 be retrieved by the calling program, using the interface defined in
776 @file{libavfilter/buffersink.h}.
778 It does not accept any parameters.
780 @c man end AUDIO SINKS
782 @chapter Video Filters
783 @c man begin VIDEO FILTERS
785 When you configure your Libav build, you can disable any of the
786 existing filters using --disable-filters.
787 The configure output will show the video filters included in your
790 Below is a description of the currently available video filters.
794 Detect frames that are (almost) completely black. Can be useful to
795 detect chapter transitions or commercials. Output lines consist of
796 the frame number of the detected frame, the percentage of blackness,
797 the position in the file if known or -1 and the timestamp in seconds.
799 In order to display the output lines, you need to set the loglevel at
800 least to the AV_LOG_INFO value.
802 It accepts the following parameters:
807 The percentage of the pixels that have to be below the threshold; it defaults to
811 The threshold below which a pixel value is considered black; it defaults to 32.
817 Apply a boxblur algorithm to the input video.
819 It accepts the following parameters:
832 The chroma and alpha parameters are optional. If not specified, they default
833 to the corresponding values set for @var{luma_radius} and
836 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
837 the radius in pixels of the box used for blurring the corresponding
838 input plane. They are expressions, and can contain the following
842 The input width and height in pixels.
845 The input chroma image width and height in pixels.
848 The horizontal and vertical chroma subsample values. For example, for the
849 pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1.
852 The radius must be a non-negative number, and must not be greater than
853 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
854 and of @code{min(cw,ch)/2} for the chroma planes.
856 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
857 how many times the boxblur filter is applied to the corresponding
865 Apply a boxblur filter with the luma, chroma, and alpha radii
868 boxblur=luma_radius=2:luma_power=1
872 Set the luma radius to 2, and alpha and chroma radius to 0:
878 Set the luma and chroma radii to a fraction of the video dimension:
880 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
887 Copy the input source unchanged to the output. This is mainly useful for
892 Crop the input video to given dimensions.
894 It accepts the following parameters:
899 The width of the output video.
902 The height of the output video.
905 The horizontal position, in the input video, of the left edge of the output
909 The vertical position, in the input video, of the top edge of the output video.
913 The parameters are expressions containing the following constants:
917 These are approximated values for the mathematical constants e
918 (Euler's number), pi (Greek pi), and phi (the golden ratio).
921 The computed values for @var{x} and @var{y}. They are evaluated for
925 The input width and height.
928 These are the same as @var{in_w} and @var{in_h}.
931 The output (cropped) width and height.
934 These are the same as @var{out_w} and @var{out_h}.
937 The number of the input frame, starting from 0.
940 The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
944 The @var{out_w} and @var{out_h} parameters specify the expressions for
945 the width and height of the output (cropped) video. They are only
946 evaluated during the configuration of the filter.
948 The default value of @var{out_w} is "in_w", and the default value of
949 @var{out_h} is "in_h".
951 The expression for @var{out_w} may depend on the value of @var{out_h},
952 and the expression for @var{out_h} may depend on @var{out_w}, but they
953 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
954 evaluated after @var{out_w} and @var{out_h}.
956 The @var{x} and @var{y} parameters specify the expressions for the
957 position of the top-left corner of the output (non-cropped) area. They
958 are evaluated for each frame. If the evaluated value is not valid, it
959 is approximated to the nearest valid value.
961 The default value of @var{x} is "(in_w-out_w)/2", and the default
962 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
963 the center of the input image.
965 The expression for @var{x} may depend on @var{y}, and the expression
966 for @var{y} may depend on @var{x}.
970 # Crop the central input area with size 100x100
971 crop=out_w=100:out_h=100
973 # Crop the central input area with size 2/3 of the input video
974 "crop=out_w=2/3*in_w:out_h=2/3*in_h"
976 # Crop the input video central square
979 # Delimit the rectangle with the top-left corner placed at position
980 # 100:100 and the right-bottom corner corresponding to the right-bottom
981 # corner of the input image
982 crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
984 # Crop 10 pixels from the left and right borders, and 20 pixels from
985 # the top and bottom borders
986 "crop=out_w=in_w-2*10:out_h=in_h-2*20"
988 # Keep only the bottom right quarter of the input image
989 "crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
991 # Crop height for getting Greek harmony
992 "crop=out_w=in_w:out_h=1/PHI*in_w"
995 "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)"
997 # Erratic camera effect depending on timestamp
998 "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)"
1000 # Set x depending on the value of y
1001 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1006 Auto-detect the crop size.
1008 It calculates the necessary cropping parameters and prints the
1009 recommended parameters via the logging system. The detected dimensions
1010 correspond to the non-black area of the input video.
1012 It accepts the following parameters:
1017 The threshold, an optional parameter between nothing (0) and
1018 everything (255). It defaults to 24.
1021 The value which the width/height should be divisible by. It defaults to
1022 16. The offset is automatically adjusted to center the video. Use 2 to
1023 get only even dimensions (needed for 4:2:2 video). 16 is best when
1024 encoding to most video codecs.
1027 A counter that determines how many frames cropdetect will reset
1028 the previously detected largest video area after. It will then start over
1029 and detect the current optimal crop area. It defaults to 0.
1031 This can be useful when channel logos distort the video area. 0
1032 indicates 'never reset', and returns the largest area encountered during
1038 Suppress a TV station logo by a simple interpolation of the surrounding
1039 pixels. Just set a rectangle covering the logo and watch it disappear
1040 (and sometimes something even uglier appear - your mileage may vary).
1042 It accepts the following parameters:
1046 Specify the top left corner coordinates of the logo. They must be
1050 Specify the width and height of the logo to clear. They must be
1054 Specify the thickness of the fuzzy edge of the rectangle (added to
1055 @var{w} and @var{h}). The default value is 4.
1058 When set to 1, a green rectangle is drawn on the screen to simplify
1059 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1060 @var{band} is set to 4. The default value is 0.
1069 Set a rectangle covering the area with top left corner coordinates 0,0
1070 and size 100x77, and a band of size 10:
1072 delogo=x=0:y=0:w=100:h=77:band=10
1079 Draw a colored box on the input image.
1081 It accepts the following parameters:
1086 Specify the top left corner coordinates of the box. It defaults to 0.
1089 Specify the width and height of the box; if 0 they are interpreted as
1090 the input width and height. It defaults to 0.
1093 Specify the color of the box to write. It can be the name of a color
1094 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1099 # Draw a black box around the edge of the input image
1102 # Draw a box with color red and an opacity of 50%
1103 drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
1108 Draw a text string or text from a specified file on top of a video, using the
1109 libfreetype library.
1111 To enable compilation of this filter, you need to configure Libav with
1112 @code{--enable-libfreetype}.
1114 The filter also recognizes strftime() sequences in the provided text
1115 and expands them accordingly. Check the documentation of strftime().
1117 It accepts the following parameters:
1122 The font file to be used for drawing text. The path must be included.
1123 This parameter is mandatory.
1126 The text string to be drawn. The text must be a sequence of UTF-8
1128 This parameter is mandatory if no file is specified with the parameter
1132 A text file containing text to be drawn. The text must be a sequence
1133 of UTF-8 encoded characters.
1135 This parameter is mandatory if no text string is specified with the
1136 parameter @var{text}.
1138 If both text and textfile are specified, an error is thrown.
1141 The offsets where text will be drawn within the video frame.
1142 It is relative to the top/left border of the output image.
1143 They accept expressions similar to the @ref{overlay} filter:
1147 The computed values for @var{x} and @var{y}. They are evaluated for
1150 @item main_w, main_h
1151 The main input width and height.
1154 These are the same as @var{main_w} and @var{main_h}.
1156 @item text_w, text_h
1157 The rendered text's width and height.
1160 These are the same as @var{text_w} and @var{text_h}.
1163 The number of frames processed, starting from 0.
1166 The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
1170 The default value of @var{x} and @var{y} is 0.
1173 The font size to be used for drawing text.
1174 The default value of @var{fontsize} is 16.
1177 The color to be used for drawing fonts.
1178 It is either a string (e.g. "red"), or in 0xRRGGBB[AA] format
1179 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1180 The default value of @var{fontcolor} is "black".
1183 The color to be used for drawing box around text.
1184 It is either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1185 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1186 The default value of @var{boxcolor} is "white".
1189 Used to draw a box around text using the background color.
1190 The value must be either 1 (enable) or 0 (disable).
1191 The default value of @var{box} is 0.
1193 @item shadowx, shadowy
1194 The x and y offsets for the text shadow position with respect to the
1195 position of the text. They can be either positive or negative
1196 values. The default value for both is "0".
1199 The color to be used for drawing a shadow behind the drawn text. It
1200 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1201 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1202 The default value of @var{shadowcolor} is "black".
1205 The flags to be used for loading the fonts.
1207 The flags map the corresponding flags supported by libfreetype, and are
1208 a combination of the following values:
1215 @item vertical_layout
1216 @item force_autohint
1219 @item ignore_global_advance_width
1221 @item ignore_transform
1228 Default value is "render".
1230 For more information consult the documentation for the FT_LOAD_*
1234 The size in number of spaces to use for rendering the tab.
1238 If true, check and fix text coords to avoid clipping.
1241 For example the command:
1243 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1246 will draw "Test Text" with font FreeSerif, using the default values
1247 for the optional parameters.
1251 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1252 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1255 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
1256 and y=50 (counting from the top-left corner of the screen), text is
1257 yellow with a red box around it. Both the text and the box have an
1260 Note that the double quotes are not necessary if spaces are not used
1261 within the parameter list.
1263 For more information about libfreetype, check:
1264 @url{http://www.freetype.org/}.
1268 Apply a fade-in/out effect to the input video.
1270 It accepts the following parameters:
1275 The effect type can be either "in" for a fade-in, or "out" for a fade-out
1279 The number of the frame to start applying the fade effect at.
1282 The number of frames that the fade effect lasts. At the end of the
1283 fade-in effect, the output video will have the same intensity as the input video.
1284 At the end of the fade-out transition, the output video will be completely black.
1290 # Fade in the first 30 frames of video
1291 fade=type=in:nb_frames=30
1293 # Fade out the last 45 frames of a 200-frame video
1294 fade=type=out:start_frame=155:nb_frames=45
1296 # Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video
1297 fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
1299 # Make the first 5 frames black, then fade in from frame 5-24
1300 fade=type=in:start_frame=5:nb_frames=20
1305 Transform the field order of the input video.
1307 It accepts the following parameters:
1312 The output field order. Valid values are @var{tff} for top field first or @var{bff}
1313 for bottom field first.
1316 The default value is "tff".
1318 The transformation is done by shifting the picture content up or down
1319 by one line, and filling the remaining line with appropriate picture content.
1320 This method is consistent with most broadcast field order converters.
1322 If the input video is not flagged as being interlaced, or it is already
1323 flagged as being of the required output field order, then this filter does
1324 not alter the incoming video.
1326 It is very useful when converting to or from PAL DV material,
1327 which is bottom field first.
1331 ./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
1336 Buffer input images and send them when they are requested.
1338 It is mainly useful when auto-inserted by the libavfilter
1341 It does not take parameters.
1345 Convert the input video to one of the specified pixel formats.
1346 Libavfilter will try to pick one that is suitable as input to
1349 It accepts the following parameters:
1353 A '|'-separated list of pixel format names, such as
1354 "pix_fmts=yuv420p|monow|rgb24".
1360 # Convert the input video to the "yuv420p" format
1361 format=pix_fmts=yuv420p
1363 # Convert the input video to any of the formats in the list
1364 format=pix_fmts=yuv420p|yuv444p|yuv410p
1370 Convert the video to specified constant framerate by duplicating or dropping
1371 frames as necessary.
1373 It accepts the following parameters:
1377 The desired output framerate.
1380 Assume the first PTS should be the given value, in seconds. This allows for
1381 padding/trimming at the start of stream. By default, no assumption is made
1382 about the first frame's expected PTS, so no padding or trimming is done.
1383 For example, this could be set to 0 to pad the beginning with duplicates of
1384 the first frame if a video stream starts after the audio stream or to trim any
1385 frames with a negative PTS.
1391 Pack two different video streams into a stereoscopic video, setting proper
1392 metadata on supported codecs. The two views should have the same size and
1393 framerate and processing will stop when the shorter video ends. Please note
1394 that you may conveniently adjust view properties with the @ref{scale} and
1397 It accepts the following parameters:
1401 The desired packing format. Supported values are:
1406 The views are next to each other (default).
1409 The views are on top of each other.
1412 The views are packed by line.
1415 The views are packed by column.
1418 The views are temporally interleaved.
1427 # Convert left and right views into a frame-sequential video
1428 avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
1430 # Convert views into a side-by-side video with the same output resolution as the input
1431 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
1437 Apply a frei0r effect to the input video.
1439 To enable the compilation of this filter, you need to install the frei0r
1440 header and configure Libav with --enable-frei0r.
1442 It accepts the following parameters:
1447 The name of the frei0r effect to load. If the environment variable
1448 @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the
1449 directories specified by the colon-separated list in @env{FREIOR_PATH}.
1450 Otherwise, the standard frei0r paths are searched, in this order:
1451 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
1452 @file{/usr/lib/frei0r-1/}.
1455 A '|'-separated list of parameters to pass to the frei0r effect.
1459 A frei0r effect parameter can be a boolean (its value is either
1460 "y" or "n"), a double, a color (specified as
1461 @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point
1462 numbers between 0.0 and 1.0, inclusive) or by an @code{av_parse_color()} color
1463 description), a position (specified as @var{X}/@var{Y}, where
1464 @var{X} and @var{Y} are floating point numbers) and/or a string.
1466 The number and types of parameters depend on the loaded effect. If an
1467 effect parameter is not specified, the default value is set.
1471 # Apply the distort0r effect, setting the first two double parameters
1472 frei0r=filter_name=distort0r:filter_params=0.5|0.01
1474 # Apply the colordistance effect, taking a color as the first parameter
1475 frei0r=colordistance:0.2/0.3/0.4
1476 frei0r=colordistance:violet
1477 frei0r=colordistance:0x112233
1479 # Apply the perspective effect, specifying the top left and top right
1481 frei0r=perspective:0.2/0.2|0.8/0.2
1484 For more information, see
1485 @url{http://piksel.org/frei0r}
1489 Fix the banding artifacts that are sometimes introduced into nearly flat
1490 regions by truncation to 8bit colordepth.
1491 Interpolate the gradients that should go where the bands are, and
1494 It is designed for playback only. Do not use it prior to
1495 lossy compression, because compression tends to lose the dither and
1496 bring back the bands.
1498 It accepts the following parameters:
1503 The maximum amount by which the filter will change any one pixel. This is also
1504 the threshold for detecting nearly flat regions. Acceptable values range from
1505 .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the
1509 The neighborhood to fit the gradient to. A larger radius makes for smoother
1510 gradients, but also prevents the filter from modifying the pixels near detailed
1511 regions. Acceptable values are 8-32; the default value is 16. Out-of-range
1512 values will be clipped to the valid range.
1517 # Default parameters
1518 gradfun=strength=1.2:radius=16
1520 # Omitting the radius
1526 Flip the input video horizontally.
1528 For example, to horizontally flip the input video with @command{avconv}:
1530 avconv -i in.avi -vf "hflip" out.avi
1535 This is a high precision/quality 3d denoise filter. It aims to reduce
1536 image noise, producing smooth images and making still images really
1537 still. It should enhance compressibility.
1539 It accepts the following optional parameters:
1543 A non-negative floating point number which specifies spatial luma strength.
1546 @item chroma_spatial
1547 A non-negative floating point number which specifies spatial chroma strength.
1548 It defaults to 3.0*@var{luma_spatial}/4.0.
1551 A floating point number which specifies luma temporal strength. It defaults to
1552 6.0*@var{luma_spatial}/4.0.
1555 A floating point number which specifies chroma temporal strength. It defaults to
1556 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
1561 Simple interlacing filter from progressive contents. This interleaves upper (or
1562 lower) lines from odd frames with lower (or upper) lines from even frames,
1563 halving the frame rate and preserving image height. A vertical lowpass filter
1564 is always applied in order to avoid twitter effects and reduce moiré patterns.
1567 Original Original New Frame
1568 Frame 'j' Frame 'j+1' (tff)
1569 ========== =========== ==================
1570 Line 0 --------------------> Frame 'j' Line 0
1571 Line 1 Line 1 ----> Frame 'j+1' Line 1
1572 Line 2 ---------------------> Frame 'j' Line 2
1573 Line 3 Line 3 ----> Frame 'j+1' Line 3
1575 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
1578 It accepts the following optional parameters:
1582 This determines whether the interlaced frame is taken from the even
1583 (tff - default) or odd (bff) lines of the progressive frame.
1586 @section lut, lutrgb, lutyuv
1588 Compute a look-up table for binding each pixel component input value
1589 to an output value, and apply it to the input video.
1591 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1592 to an RGB input video.
1594 These filters accept the following parameters:
1596 @item @var{c0} (first pixel component)
1597 @item @var{c1} (second pixel component)
1598 @item @var{c2} (third pixel component)
1599 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
1601 @item @var{r} (red component)
1602 @item @var{g} (green component)
1603 @item @var{b} (blue component)
1604 @item @var{a} (alpha component)
1606 @item @var{y} (Y/luminance component)
1607 @item @var{u} (U/Cb component)
1608 @item @var{v} (V/Cr component)
1611 Each of them specifies the expression to use for computing the lookup table for
1612 the corresponding pixel component values.
1614 The exact component associated to each of the @var{c*} options depends on the
1617 The @var{lut} filter requires either YUV or RGB pixel formats in input,
1618 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
1620 The expressions can contain the following constants and functions:
1624 These are approximated values for the mathematical constants e
1625 (Euler's number), pi (Greek pi), and phi (the golden ratio).
1628 The input width and height.
1631 The input value for the pixel component.
1634 The input value, clipped to the @var{minval}-@var{maxval} range.
1637 The maximum value for the pixel component.
1640 The minimum value for the pixel component.
1643 The negated value for the pixel component value, clipped to the
1644 @var{minval}-@var{maxval} range; it corresponds to the expression
1645 "maxval-clipval+minval".
1648 The computed value in @var{val}, clipped to the
1649 @var{minval}-@var{maxval} range.
1651 @item gammaval(gamma)
1652 The computed gamma correction value of the pixel component value,
1653 clipped to the @var{minval}-@var{maxval} range. It corresponds to the
1655 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1659 All expressions default to "val".
1663 # Negate input video
1664 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1665 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1667 # The above is the same as
1668 lutrgb="r=negval:g=negval:b=negval"
1669 lutyuv="y=negval:u=negval:v=negval"
1674 # Remove chroma components, turning the video into a graytone image
1675 lutyuv="u=128:v=128"
1677 # Apply a luma burning effect
1680 # Remove green and blue components
1683 # Set a constant alpha channel value on input
1684 format=rgba,lutrgb=a="maxval-minval/2"
1686 # Correct luminance gamma by a factor of 0.5
1687 lutyuv=y=gammaval(0.5)
1694 It accepts an integer in input; if non-zero it negates the
1695 alpha component (if available). The default value in input is 0.
1699 Force libavfilter not to use any of the specified pixel formats for the
1700 input to the next filter.
1702 It accepts the following parameters:
1706 A '|'-separated list of pixel format names, such as
1707 apix_fmts=yuv420p|monow|rgb24".
1713 # Force libavfilter to use a format different from "yuv420p" for the
1714 # input to the vflip filter
1715 noformat=pix_fmts=yuv420p,vflip
1717 # Convert the input video to any of the formats not contained in the list
1718 noformat=yuv420p|yuv444p|yuv410p
1723 Pass the video source unchanged to the output.
1727 Apply a video transform using libopencv.
1729 To enable this filter, install the libopencv library and headers and
1730 configure Libav with --enable-libopencv.
1732 It accepts the following parameters:
1737 The name of the libopencv filter to apply.
1740 The parameters to pass to the libopencv filter. If not specified, the default
1745 Refer to the official libopencv documentation for more precise
1747 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1749 Several libopencv filters are supported; see the following subsections.
1754 Dilate an image by using a specific structuring element.
1755 It corresponds to the libopencv function @code{cvDilate}.
1757 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
1759 @var{struct_el} represents a structuring element, and has the syntax:
1760 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1762 @var{cols} and @var{rows} represent the number of columns and rows of
1763 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1764 point, and @var{shape} the shape for the structuring element. @var{shape}
1765 must be "rect", "cross", "ellipse", or "custom".
1767 If the value for @var{shape} is "custom", it must be followed by a
1768 string of the form "=@var{filename}". The file with name
1769 @var{filename} is assumed to represent a binary image, with each
1770 printable character corresponding to a bright pixel. When a custom
1771 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1772 or columns and rows of the read file are assumed instead.
1774 The default value for @var{struct_el} is "3x3+0x0/rect".
1776 @var{nb_iterations} specifies the number of times the transform is
1777 applied to the image, and defaults to 1.
1781 # Use the default values
1784 # Dilate using a structuring element with a 5x5 cross, iterating two times
1785 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
1787 # Read the shape from the file diamond.shape, iterating two times.
1788 # The file diamond.shape may contain a pattern of characters like this
1794 # The specified columns and rows are ignored
1795 # but the anchor point coordinates are not
1796 ocv=dilate:0x0+2x2/custom=diamond.shape|2
1801 Erode an image by using a specific structuring element.
1802 It corresponds to the libopencv function @code{cvErode}.
1804 It accepts the parameters: @var{struct_el}:@var{nb_iterations},
1805 with the same syntax and semantics as the @ref{dilate} filter.
1809 Smooth the input video.
1811 The filter takes the following parameters:
1812 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
1814 @var{type} is the type of smooth filter to apply, and must be one of
1815 the following values: "blur", "blur_no_scale", "median", "gaussian",
1816 or "bilateral". The default value is "gaussian".
1818 The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4}
1819 depend on the smooth type. @var{param1} and
1820 @var{param2} accept integer positive values or 0. @var{param3} and
1821 @var{param4} accept floating point values.
1823 The default value for @var{param1} is 3. The default value for the
1824 other parameters is 0.
1826 These parameters correspond to the parameters assigned to the
1827 libopencv function @code{cvSmooth}.
1832 Overlay one video on top of another.
1834 It takes two inputs and has one output. The first input is the "main"
1835 video on which the second input is overlayed.
1837 It accepts the following parameters:
1842 The horizontal position of the left edge of the overlaid video on the main video.
1845 The vertical position of the top edge of the overlaid video on the main video.
1849 The parameters are expressions containing the following parameters:
1852 @item main_w, main_h
1853 The main input width and height.
1856 These are the same as @var{main_w} and @var{main_h}.
1858 @item overlay_w, overlay_h
1859 The overlay input width and height.
1862 These are the same as @var{overlay_w} and @var{overlay_h}.
1865 The action to take when EOF is encountered on the secondary input; it accepts
1866 one of the following values:
1870 Repeat the last frame (the default).
1874 Pass the main input through.
1879 Be aware that frames are taken from each input video in timestamp
1880 order, hence, if their initial timestamps differ, it is a a good idea
1881 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1882 have them begin in the same zero timestamp, as the example for
1883 the @var{movie} filter does.
1887 # Draw the overlay at 10 pixels from the bottom right
1888 # corner of the main video
1889 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
1891 # Insert a transparent PNG logo in the bottom left corner of the input
1892 avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
1894 # Insert 2 different transparent PNG logos (second logo on bottom
1896 avconv -i input -i logo1 -i logo2 -filter_complex
1897 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
1899 # Add a transparent color layer on top of the main video;
1900 # WxH specifies the size of the main input to the overlay filter
1901 color=red@.3:WxH [over]; [in][over] overlay [out]
1903 # Mask 10-20 seconds of a video by applying the delogo filter to a section
1904 avconv -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
1905 -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]'
1909 You can chain together more overlays but the efficiency of such
1910 approach is yet to be tested.
1914 Add paddings to the input image, and place the original input at the
1915 provided @var{x}, @var{y} coordinates.
1917 It accepts the following parameters:
1922 Specify the size of the output image with the paddings added. If the
1923 value for @var{width} or @var{height} is 0, the corresponding input size
1924 is used for the output.
1926 The @var{width} expression can reference the value set by the
1927 @var{height} expression, and vice versa.
1929 The default value of @var{width} and @var{height} is 0.
1933 Specify the offsets to place the input image at within the padded area,
1934 with respect to the top/left border of the output image.
1936 The @var{x} expression can reference the value set by the @var{y}
1937 expression, and vice versa.
1939 The default value of @var{x} and @var{y} is 0.
1943 Specify the color of the padded area. It can be the name of a color
1944 (case insensitive match) or an 0xRRGGBB[AA] sequence.
1946 The default value of @var{color} is "black".
1950 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1951 expressions containing the following constants:
1955 These are approximated values for the mathematical constants e
1956 (Euler's number), pi (Greek pi), and phi (the golden ratio).
1959 The input video width and height.
1962 These are the same as @var{in_w} and @var{in_h}.
1965 The output width and height (the size of the padded area), as
1966 specified by the @var{width} and @var{height} expressions.
1969 These are the same as @var{out_w} and @var{out_h}.
1972 The x and y offsets as specified by the @var{x} and @var{y}
1973 expressions, or NAN if not yet specified.
1976 The input display aspect ratio, same as @var{iw} / @var{ih}.
1979 The horizontal and vertical chroma subsample values. For example for the
1980 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1986 # Add paddings with the color "violet" to the input video. The output video
1987 # size is 640x480, and the top-left corner of the input video is placed at
1989 pad=width=640:height=480:x=0:y=40:color=violet
1991 # Pad the input to get an output with dimensions increased by 3/2,
1992 # and put the input video at the center of the padded area
1993 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1995 # Pad the input to get a squared output with size equal to the maximum
1996 # value between the input width and height, and put the input video at
1997 # the center of the padded area
1998 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2000 # Pad the input to get a final w/h ratio of 16:9
2001 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2003 # Double the output size and put the input video in the bottom-right
2004 # corner of the output padded area
2005 pad="2*iw:2*ih:ow-iw:oh-ih"
2008 @section pixdesctest
2010 Pixel format descriptor test filter, mainly useful for internal
2011 testing. The output video should be equal to the input video.
2015 format=monow, pixdesctest
2018 can be used to test the monowhite pixel format descriptor definition.
2023 Scale the input video and/or convert the image format.
2025 It accepts the following parameters:
2030 The output video width.
2033 The output video height.
2037 The parameters @var{w} and @var{h} are expressions containing
2038 the following constants:
2042 These are approximated values for the mathematical constants e
2043 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2046 The input width and height.
2049 These are the same as @var{in_w} and @var{in_h}.
2052 The output (cropped) width and height.
2055 These are the same as @var{out_w} and @var{out_h}.
2058 This is the same as @var{iw} / @var{ih}.
2061 input sample aspect ratio
2064 The input display aspect ratio; it is the same as
2065 (@var{iw} / @var{ih}) * @var{sar}.
2068 The horizontal and vertical chroma subsample values. For example, for the
2069 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2072 If the input image format is different from the format requested by
2073 the next filter, the scale filter will convert the input to the
2076 If the value for @var{w} or @var{h} is 0, the respective input
2077 size is used for the output.
2079 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
2080 respective output size, a value that maintains the aspect ratio of the input
2083 The default value of @var{w} and @var{h} is 0.
2087 # Scale the input video to a size of 200x100
2090 # Scale the input to 2x
2092 # The above is the same as
2095 # Scale the input to half the original size
2098 # Increase the width, and set the height to the same size
2101 # Seek Greek harmony
2105 # Increase the height, and set the width to 3/2 of the height
2106 scale=w=3/2*oh:h=3/5*ih
2108 # Increase the size, making the size a multiple of the chroma
2109 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2111 # Increase the width to a maximum of 500 pixels,
2112 # keeping the same aspect ratio as the input
2113 scale=w='min(500\, iw*3/2):h=-1'
2117 Select frames to pass in output.
2119 It accepts the following parameters:
2124 An expression, which is evaluated for each input frame. If the expression is
2125 evaluated to a non-zero value, the frame is selected and passed to the output,
2126 otherwise it is discarded.
2130 The expression can contain the following constants:
2134 These are approximated values for the mathematical constants e
2135 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2138 The (sequential) number of the filtered frame, starting from 0.
2141 The (sequential) number of the selected frame, starting from 0.
2143 @item prev_selected_n
2144 The sequential number of the last selected frame. It's NAN if undefined.
2147 The timebase of the input timestamps.
2150 The PTS (Presentation TimeStamp) of the filtered video frame,
2151 expressed in @var{TB} units. It's NAN if undefined.
2154 The PTS of the filtered video frame,
2155 expressed in seconds. It's NAN if undefined.
2158 The PTS of the previously filtered video frame. It's NAN if undefined.
2160 @item prev_selected_pts
2161 The PTS of the last previously filtered video frame. It's NAN if undefined.
2163 @item prev_selected_t
2164 The PTS of the last previously selected video frame. It's NAN if undefined.
2167 The PTS of the first video frame in the video. It's NAN if undefined.
2170 The time of the first video frame in the video. It's NAN if undefined.
2173 The type of the filtered frame. It can assume one of the following
2185 @item interlace_type
2186 The frame interlace type. It can assume one of the following values:
2189 The frame is progressive (not interlaced).
2191 The frame is top-field-first.
2193 The frame is bottom-field-first.
2197 This is 1 if the filtered frame is a key-frame, 0 otherwise.
2201 The default value of the select expression is "1".
2206 # Select all the frames in input
2209 # The above is the same as
2215 # Select only I-frames
2216 select='expr=eq(pict_type\,I)'
2218 # Select one frame per 100
2219 select='not(mod(n\,100))'
2221 # Select only frames contained in the 10-20 time interval
2222 select='gte(t\,10)*lte(t\,20)'
2224 # Select only I frames contained in the 10-20 time interval
2225 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2227 # Select frames with a minimum distance of 10 seconds
2228 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2234 Set the Display Aspect Ratio for the filter output video.
2236 This is done by changing the specified Sample (aka Pixel) Aspect
2237 Ratio, according to the following equation:
2238 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2240 Keep in mind that this filter does not modify the pixel dimensions of
2241 the video frame. Also, the display aspect ratio set by this filter may
2242 be changed by later filters in the filterchain, e.g. in case of
2243 scaling or if another "setdar" or a "setsar" filter is applied.
2245 It accepts the following parameters:
2250 The output display aspect ratio.
2254 The parameter @var{dar} is an expression containing
2255 the following constants:
2259 These are approximated values for the mathematical constants e
2260 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2263 The input width and height.
2266 This is the same as @var{w} / @var{h}.
2269 The input sample aspect ratio.
2272 The input display aspect ratio. It is the same as
2273 (@var{w} / @var{h}) * @var{sar}.
2276 The horizontal and vertical chroma subsample values. For example, for the
2277 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2280 To change the display aspect ratio to 16:9, specify:
2283 # The above is equivalent to
2287 Also see the the @ref{setsar} filter documentation.
2291 Change the PTS (presentation timestamp) of the input video frames.
2293 It accepts the following parameters:
2298 The expression which is evaluated for each frame to construct its timestamp.
2302 The expression is evaluated through the eval API and can contain the following
2307 The presentation timestamp in input.
2310 These are approximated values for the mathematical constants e
2311 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2314 The count of the input frame, starting from 0.
2317 The PTS of the first video frame.
2320 State whether the current frame is interlaced.
2323 The previous input PTS.
2326 The previous output PTS.
2329 The wallclock (RTC) time in microseconds.
2332 The wallclock (RTC) time at the start of the movie in microseconds.
2335 The timebase of the input timestamps.
2342 # Start counting the PTS from zero
2343 setpts=expr=PTS-STARTPTS
2354 # Fixed rate 25 fps with some jitter
2355 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2357 # Generate timestamps from a "live source" and rebase onto the current timebase
2358 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
2364 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2366 Note that as a consequence of the application of this filter, the
2367 output display aspect ratio will change according to the following
2369 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2371 Keep in mind that the sample aspect ratio set by this filter may be
2372 changed by later filters in the filterchain, e.g. if another "setsar"
2373 or a "setdar" filter is applied.
2375 It accepts the following parameters:
2380 The output sample aspect ratio.
2384 The parameter @var{sar} is an expression containing
2385 the following constants:
2389 These are approximated values for the mathematical constants e
2390 (Euler's number), pi (Greek pi), and phi (the golden ratio).
2393 The input width and height.
2396 These are the same as @var{w} / @var{h}.
2399 The input sample aspect ratio.
2402 The input display aspect ratio. It is the same as
2403 (@var{w} / @var{h}) * @var{sar}.
2406 Horizontal and vertical chroma subsample values. For example, for the
2407 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2410 To change the sample aspect ratio to 10:11, specify:
2417 Set the timebase to use for the output frames timestamps.
2418 It is mainly useful for testing timebase configuration.
2420 It accepts the following parameters:
2425 The expression which is evaluated into the output timebase.
2429 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
2430 default timebase), and "intb" (the input timebase).
2432 The default value for the input is "intb".
2437 # Set the timebase to 1/25
2440 # Set the timebase to 1/10
2443 # Set the timebase to 1001/1000
2446 #Set the timebase to 2*intb
2449 #Set the default timebase value
2455 Show a line containing various information for each input video frame.
2456 The input video is not modified.
2458 The shown line contains a sequence of key/value pairs of the form
2459 @var{key}:@var{value}.
2461 It accepts the following parameters:
2465 The (sequential) number of the input frame, starting from 0.
2468 The Presentation TimeStamp of the input frame, expressed as a number of
2469 time base units. The time base unit depends on the filter input pad.
2472 The Presentation TimeStamp of the input frame, expressed as a number of
2476 The position of the frame in the input stream, or -1 if this information is
2477 unavailable and/or meaningless (for example in case of synthetic video).
2480 The pixel format name.
2483 The sample aspect ratio of the input frame, expressed in the form
2484 @var{num}/@var{den}.
2487 The size of the input frame, expressed in the form
2488 @var{width}x@var{height}.
2491 The type of interlaced mode ("P" for "progressive", "T" for top field first, "B"
2492 for bottom field first).
2495 This is 1 if the frame is a key frame, 0 otherwise.
2498 The picture type of the input frame ("I" for an I-frame, "P" for a
2499 P-frame, "B" for a B-frame, or "?" for an unknown type).
2500 Also refer to the documentation of the @code{AVPictureType} enum and of
2501 the @code{av_get_picture_type_char} function defined in
2502 @file{libavutil/avutil.h}.
2505 The Adler-32 checksum of all the planes of the input frame.
2507 @item plane_checksum
2508 The Adler-32 checksum of each plane of the input frame, expressed in the form
2509 "[@var{c0} @var{c1} @var{c2} @var{c3}]".
2512 @section shuffleplanes
2514 Reorder and/or duplicate video planes.
2516 It accepts the following parameters:
2521 The index of the input plane to be used as the first output plane.
2524 The index of the input plane to be used as the second output plane.
2527 The index of the input plane to be used as the third output plane.
2530 The index of the input plane to be used as the fourth output plane.
2534 The first plane has the index 0. The default is to keep the input unchanged.
2536 Swap the second and third planes of the input:
2538 avconv -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
2543 Split input video into several identical outputs.
2545 It accepts a single parameter, which specifies the number of outputs. If
2546 unspecified, it defaults to 2.
2548 Create 5 copies of the input video:
2550 avconv -i INPUT -filter_complex split=5 OUTPUT
2555 Transpose rows with columns in the input video and optionally flip it.
2557 It accepts the following parameters:
2562 The direction of the transpose.
2566 The direction can assume the following values:
2570 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2578 Rotate by 90 degrees clockwise, that is:
2586 Rotate by 90 degrees counterclockwise, that is:
2594 Rotate by 90 degrees clockwise and vertically flip, that is:
2603 Trim the input so that the output contains one continuous subpart of the input.
2605 It accepts the following parameters:
2608 The timestamp (in seconds) of the start of the kept section. The frame with the
2609 timestamp @var{start} will be the first frame in the output.
2612 The timestamp (in seconds) of the first frame that will be dropped. The frame
2613 immediately preceding the one with the timestamp @var{end} will be the last
2614 frame in the output.
2617 This is the same as @var{start}, except this option sets the start timestamp
2618 in timebase units instead of seconds.
2621 This is the same as @var{end}, except this option sets the end timestamp
2622 in timebase units instead of seconds.
2625 The maximum duration of the output in seconds.
2628 The number of the first frame that should be passed to the output.
2631 The number of the first frame that should be dropped.
2634 Note that the first two sets of the start/end options and the @option{duration}
2635 option look at the frame timestamp, while the _frame variants simply count the
2636 frames that pass through the filter. Also note that this filter does not modify
2637 the timestamps. If you wish for the output timestamps to start at zero, insert a
2638 setpts filter after the trim filter.
2640 If multiple start or end options are set, this filter tries to be greedy and
2641 keep all the frames that match at least one of the specified constraints. To keep
2642 only the part that matches all the constraints at once, chain multiple trim
2645 The defaults are such that all the input is kept. So it is possible to set e.g.
2646 just the end values to keep everything before the specified time.
2651 Drop everything except the second minute of input:
2653 avconv -i INPUT -vf trim=60:120
2657 Keep only the first second:
2659 avconv -i INPUT -vf trim=duration=1
2665 Sharpen or blur the input video.
2667 It accepts the following parameters:
2672 Set the luma matrix horizontal size. It must be an integer between 3
2673 and 13. The default value is 5.
2676 Set the luma matrix vertical size. It must be an integer between 3
2677 and 13. The default value is 5.
2680 Set the luma effect strength. It must be a floating point number between -2.0
2681 and 5.0. The default value is 1.0.
2683 @item chroma_msize_x
2684 Set the chroma matrix horizontal size. It must be an integer between 3
2685 and 13. The default value is 5.
2687 @item chroma_msize_y
2688 Set the chroma matrix vertical size. It must be an integer between 3
2689 and 13. The default value is 5.
2692 Set the chroma effect strength. It must be a floating point number between -2.0
2693 and 5.0. The default value is 0.0.
2697 Negative values for the amount will blur the input video, while positive
2698 values will sharpen. All parameters are optional and default to the
2699 equivalent of the string '5:5:1.0:5:5:0.0'.
2702 # Strong luma sharpen effect parameters
2703 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
2705 # A strong blur of both luma and chroma parameters
2706 unsharp=7:7:-2:7:7:-2
2708 # Use the default values with @command{avconv}
2709 ./avconv -i in.avi -vf "unsharp" out.mp4
2714 Flip the input video vertically.
2717 ./avconv -i in.avi -vf "vflip" out.avi
2722 Deinterlace the input video ("yadif" means "yet another deinterlacing
2725 It accepts the following parameters:
2730 The interlacing mode to adopt. It accepts one of the following values:
2734 Output one frame for each frame.
2736 Output one frame for each field.
2738 Like 0, but it skips the spatial interlacing check.
2740 Like 1, but it skips the spatial interlacing check.
2743 The default value is 0.
2746 The picture field parity assumed for the input interlaced video. It accepts one
2747 of the following values:
2751 Assume the top field is first.
2753 Assume the bottom field is first.
2755 Enable automatic detection of field parity.
2758 The default value is -1.
2759 If the interlacing is unknown or the decoder does not export this information,
2760 top field first will be assumed.
2763 Whether the deinterlacer should trust the interlaced flag and only deinterlace
2764 frames marked as interlaced.
2768 Deinterlace all frames.
2770 Only deinterlace frames marked as interlaced.
2773 The default value is 0.
2777 @c man end VIDEO FILTERS
2779 @chapter Video Sources
2780 @c man begin VIDEO SOURCES
2782 Below is a description of the currently available video sources.
2786 Buffer video frames, and make them available to the filter chain.
2788 This source is mainly intended for a programmatic use, in particular
2789 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2791 It accepts the following parameters:
2796 The input video width.
2799 The input video height.
2802 The name of the input video pixel format.
2805 The time base used for input timestamps.
2808 The sample (pixel) aspect ratio of the input video.
2814 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
2817 will instruct the source to accept video frames with size 320x240 and
2818 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2819 square pixels (1:1 sample aspect ratio).
2823 Provide an uniformly colored input.
2825 It accepts the following parameters:
2830 Specify the color of the source. It can be the name of a color (case
2831 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2832 alpha specifier. The default value is "black".
2835 Specify the size of the sourced video, it may be a string of the form
2836 @var{width}x@var{height}, or the name of a size abbreviation. The
2837 default value is "320x240".
2840 Specify the frame rate of the sourced video, as the number of frames
2841 generated per second. It has to be a string in the format
2842 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
2843 number or a valid video frame rate abbreviation. The default value is
2848 The following graph description will generate a red source
2849 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2850 frames per second, which will be overlayed over the source connected
2851 to the pad with identifier "in":
2854 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2859 Read a video stream from a movie container.
2861 Note that this source is a hack that bypasses the standard input path. It can be
2862 useful in applications that do not support arbitrary filter graphs, but its use
2863 is discouraged in those that do. It should never be used with
2864 @command{avconv}; the @option{-filter_complex} option fully replaces it.
2866 It accepts the following parameters:
2871 The name of the resource to read (not necessarily a file; it can also be a
2872 device or a stream accessed through some protocol).
2874 @item format_name, f
2875 Specifies the format assumed for the movie to read, and can be either
2876 the name of a container or an input device. If not specified, the
2877 format is guessed from @var{movie_name} or by probing.
2879 @item seek_point, sp
2880 Specifies the seek point in seconds. The frames will be output
2881 starting from this seek point. The parameter is evaluated with
2882 @code{av_strtod}, so the numerical value may be suffixed by an IS
2883 postfix. The default value is "0".
2885 @item stream_index, si
2886 Specifies the index of the video stream to read. If the value is -1,
2887 the most suitable video stream will be automatically selected. The default
2892 It allows overlaying a second video on top of the main input of
2893 a filtergraph, as shown in this graph:
2895 input -----------> deltapts0 --> overlay --> output
2898 movie --> scale--> deltapts1 -------+
2903 # Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it
2904 # on top of the input labelled "in"
2905 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2906 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2908 # Read from a video4linux2 device, and overlay it on top of the input
2910 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2911 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2917 Null video source: never return images. It is mainly useful as a
2918 template and to be employed in analysis / debugging tools.
2920 It accepts a string of the form
2921 @var{width}:@var{height}:@var{timebase} as an optional parameter.
2923 @var{width} and @var{height} specify the size of the configured
2924 source. The default values of @var{width} and @var{height} are
2925 respectively 352 and 288 (corresponding to the CIF size format).
2927 @var{timebase} specifies an arithmetic expression representing a
2928 timebase. The expression can contain the constants "PI", "E", "PHI", and
2929 "AVTB" (the default timebase), and defaults to the value "AVTB".
2933 Provide a frei0r source.
2935 To enable compilation of this filter you need to install the frei0r
2936 header and configure Libav with --enable-frei0r.
2938 This source accepts the following parameters:
2943 The size of the video to generate. It may be a string of the form
2944 @var{width}x@var{height} or a frame size abbreviation.
2947 The framerate of the generated video. It may be a string of the form
2948 @var{num}/@var{den} or a frame rate abbreviation.
2951 The name to the frei0r source to load. For more information regarding frei0r and
2952 how to set the parameters, read the @ref{frei0r} section in the video filters
2956 A '|'-separated list of parameters to pass to the frei0r source.
2962 # Generate a frei0r partik0l source with size 200x200 and framerate 10
2963 # which is overlayed on the overlay filter main input
2964 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
2967 @section rgbtestsrc, testsrc
2969 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2970 detecting RGB vs BGR issues. You should see a red, green and blue
2971 stripe from top to bottom.
2973 The @code{testsrc} source generates a test video pattern, showing a
2974 color pattern, a scrolling gradient and a timestamp. This is mainly
2975 intended for testing purposes.
2977 The sources accept the following parameters:
2982 Specify the size of the sourced video, it may be a string of the form
2983 @var{width}x@var{height}, or the name of a size abbreviation. The
2984 default value is "320x240".
2987 Specify the frame rate of the sourced video, as the number of frames
2988 generated per second. It has to be a string in the format
2989 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point
2990 number or a valid video frame rate abbreviation. The default value is
2994 Set the sample aspect ratio of the sourced video.
2997 Set the video duration of the sourced video. The accepted syntax is:
2999 [-]HH[:MM[:SS[.m...]]]
3002 Also see the the @code{av_parse_time()} function.
3004 If not specified, or the expressed duration is negative, the video is
3005 supposed to be generated forever.
3008 For example the following:
3010 testsrc=duration=5.3:size=qcif:rate=10
3013 will generate a video with a duration of 5.3 seconds, with size
3014 176x144 and a framerate of 10 frames per second.
3016 @c man end VIDEO SOURCES
3018 @chapter Video Sinks
3019 @c man begin VIDEO SINKS
3021 Below is a description of the currently available video sinks.
3025 Buffer video frames, and make them available to the end of the filter
3028 This sink is intended for programmatic use through the interface defined in
3029 @file{libavfilter/buffersink.h}.
3033 Null video sink: do absolutely nothing with the input video. It is
3034 mainly useful as a template and for use in analysis / debugging
3037 @c man end VIDEO SINKS