1 @chapter Filtergraph description
2 @c man begin FILTERGRAPH DESCRIPTION
4 A filtergraph is a directed graph of connected filters. It can contain
5 cycles, and there can be multiple links between a pair of
6 filters. Each link has one input pad on one side connecting it to one
7 filter from which it takes its input, and one output pad on the other
8 side connecting it to the one filter accepting its output.
10 Each filter in a filtergraph is an instance of a filter class
11 registered in the application, which defines the features and the
12 number of input and output pads of the filter.
14 A filter with no input pads is called a "source", a filter with no
15 output pads is called a "sink".
17 @anchor{Filtergraph syntax}
18 @section Filtergraph syntax
20 A filtergraph can be represented using a textual representation, which is
21 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
22 options in @command{avconv} and @option{-vf} in @command{avplay}, and by the
23 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
24 @file{libavfilter/avfilter.h}.
26 A filterchain consists of a sequence of connected filters, each one
27 connected to the previous one in the sequence. A filterchain is
28 represented by a list of ","-separated filter descriptions.
30 A filtergraph consists of a sequence of filterchains. A sequence of
31 filterchains is represented by a list of ";"-separated filterchain
34 A filter is represented by a string of the form:
35 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
37 @var{filter_name} is the name of the filter class of which the
38 described filter is an instance of, and has to be the name of one of
39 the filter classes registered in the program.
40 The name of the filter class is optionally followed by a string
43 @var{arguments} is a string which contains the parameters used to
44 initialize the filter instance. It may have one of the two allowed forms:
48 A ':'-separated list of @var{key=value} pairs.
51 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
52 the option names in the order they are declared. E.g. the @code{fade} filter
53 declares three options in this order -- @option{type}, @option{start_frame} and
54 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
55 @var{in} is assigned to the option @option{type}, @var{0} to
56 @option{start_frame} and @var{30} to @option{nb_frames}.
60 If the option value itself is a list of items (e.g. the @code{format} filter
61 takes a list of pixel formats), the items in the list are usually separated by
64 The list of arguments can be quoted using the character "'" as initial
65 and ending mark, and the character '\' for escaping the characters
66 within the quoted text; otherwise the argument string is considered
67 terminated when the next special character (belonging to the set
68 "[]=;,") is encountered.
70 The name and arguments of the filter are optionally preceded and
71 followed by a list of link labels.
72 A link label allows to name a link and associate it to a filter output
73 or input pad. The preceding labels @var{in_link_1}
74 ... @var{in_link_N}, are associated to the filter input pads,
75 the following labels @var{out_link_1} ... @var{out_link_M}, are
76 associated to the output pads.
78 When two link labels with the same name are found in the
79 filtergraph, a link between the corresponding input and output pad is
82 If an output pad is not labelled, it is linked by default to the first
83 unlabelled input pad of the next filter in the filterchain.
84 For example in the filterchain:
86 nullsrc, split[L1], [L2]overlay, nullsink
88 the split filter instance has two output pads, and the overlay filter
89 instance two input pads. The first output pad of split is labelled
90 "L1", the first input pad of overlay is labelled "L2", and the second
91 output pad of split is linked to the second input pad of overlay,
92 which are both unlabelled.
94 In a complete filterchain all the unlabelled filter input and output
95 pads must be connected. A filtergraph is considered valid if all the
96 filter input and output pads of all the filterchains are connected.
98 Libavfilter will automatically insert scale filters where format
99 conversion is required. It is possible to specify swscale flags
100 for those automatically inserted scalers by prepending
101 @code{sws_flags=@var{flags};}
102 to the filtergraph description.
104 Follows a BNF description for the filtergraph syntax:
106 @var{NAME} ::= sequence of alphanumeric characters and '_'
107 @var{LINKLABEL} ::= "[" @var{NAME} "]"
108 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
109 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
110 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
111 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
112 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
115 @c man end FILTERGRAPH DESCRIPTION
117 @chapter Audio Filters
118 @c man begin AUDIO FILTERS
120 When you configure your Libav build, you can disable any of the
121 existing filters using --disable-filters.
122 The configure output will show the audio filters included in your
125 Below is a description of the currently available audio filters.
129 Convert the input audio to one of the specified formats. The framework will
130 negotiate the most appropriate format to minimize conversions.
132 The filter accepts the following named parameters:
136 A '|'-separated list of requested sample formats.
139 A '|'-separated list of requested sample rates.
141 @item channel_layouts
142 A '|'-separated list of requested channel layouts.
146 If a parameter is omitted, all values are allowed.
148 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
150 aformat=sample_fmts=u8|s16:channel_layouts=stereo
155 Mixes multiple audio inputs into a single output.
159 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
161 will mix 3 input audio streams to a single output with the same duration as the
162 first input and a dropout transition time of 3 seconds.
164 The filter accepts the following named parameters:
168 Number of inputs. If unspecified, it defaults to 2.
171 How to determine the end-of-stream.
175 Duration of longest input. (default)
178 Duration of shortest input.
181 Duration of first input.
185 @item dropout_transition
186 Transition time, in seconds, for volume renormalization when an input
187 stream ends. The default value is 2 seconds.
193 Pass the audio source unchanged to the output.
197 Change the PTS (presentation timestamp) of the input audio frames.
199 This filter accepts the following options:
204 The expression which is evaluated for each frame to construct its timestamp.
208 The expression is evaluated through the eval API and can contain the following
213 the presentation timestamp in input
225 Number of the audio samples pass through the filter so far, starting at 0.
228 Number of the audio samples in the current frame.
234 the PTS of the first frame
243 wallclock (RTC) time in microseconds
246 wallclock (RTC) time at the start of the movie in microseconds
250 Some examples follow:
253 # start counting PTS from zero
254 asetpts=expr=PTS-STARTPTS
256 #generate timestamps by counting samples
259 # generate timestamps from a "live source" and rebase onto the current timebase
260 asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
266 Show a line containing various information for each input audio frame.
267 The input audio is not modified.
269 The shown line contains a sequence of key/value pairs of the form
270 @var{key}:@var{value}.
272 A description of each shown parameter follows:
276 sequential number of the input frame, starting from 0
279 Presentation timestamp of the input frame, in time base units; the time base
280 depends on the filter input pad, and is usually 1/@var{sample_rate}.
283 presentation timestamp of the input frame in seconds
292 sample rate for the audio frame
295 number of samples (per channel) in the frame
298 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
299 the data is treated as if all the planes were concatenated.
301 @item plane_checksums
302 A list of Adler-32 checksums for each data plane.
307 Split input audio into several identical outputs.
309 The filter accepts a single parameter which specifies the number of outputs. If
310 unspecified, it defaults to 2.
314 avconv -i INPUT -filter_complex asplit=5 OUTPUT
316 will create 5 copies of the input audio.
319 Synchronize audio data with timestamps by squeezing/stretching it and/or
320 dropping samples/adding silence when needed.
322 The filter accepts the following named parameters:
326 Enable stretching/squeezing the data to make it match the timestamps. Disabled
327 by default. When disabled, time gaps are covered with silence.
330 Minimum difference between timestamps and audio data (in seconds) to trigger
331 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
332 this filter, try setting this parameter to 0.
335 Maximum compensation in samples per second. Relevant only with compensate=1.
339 Assume the first pts should be this value. The time base is 1 / sample rate.
340 This allows for padding/trimming at the start of stream. By default, no
341 assumption is made about the first frame's expected pts, so no padding or
342 trimming is done. For example, this could be set to 0 to pad the beginning with
343 silence if an audio stream starts after the video stream or to trim any samples
344 with a negative pts due to encoder delay.
349 Trim the input so that the output contains one continuous subpart of the input.
351 This filter accepts the following options:
354 Timestamp (in seconds) of the start of the kept section. I.e. the audio sample
355 with the timestamp @var{start} will be the first sample in the output.
358 Timestamp (in seconds) of the first audio sample that will be dropped. I.e. the
359 audio sample immediately preceding the one with the timestamp @var{end} will be
360 the last sample in the output.
363 Same as @var{start}, except this option sets the start timestamp in samples
367 Same as @var{end}, except this option sets the end timestamp in samples instead
371 Maximum duration of the output in seconds.
374 Number of the first sample that should be passed to output.
377 Number of the first sample that should be dropped.
380 Note that the first two sets of the start/end options and the @option{duration}
381 option look at the frame timestamp, while the _sample options simply count the
382 samples that pass through the filter. So start/end_pts and start/end_sample will
383 give different results when the timestamps are wrong, inexact or do not start at
384 zero. Also note that this filter does not modify the timestamps. If you wish
385 that the output timestamps start at zero, insert the asetpts filter after the
388 If multiple start or end options are set, this filter tries to be greedy and
389 keep all samples that match at least one of the specified constraints. To keep
390 only the part that matches all the constraints at once, chain multiple atrim
393 The defaults are such that all the input is kept. So it is possible to set e.g.
394 just the end values to keep everything before the specified time.
399 drop everything except the second minute of input
401 avconv -i INPUT -af atrim=60:120
405 keep only the first 1000 samples
407 avconv -i INPUT -af atrim=end_sample=1000
412 @section channelsplit
413 Split each channel in input audio stream into a separate output stream.
415 This filter accepts the following named parameters:
418 Channel layout of the input stream. Default is "stereo".
421 For example, assuming a stereo input MP3 file
423 avconv -i in.mp3 -filter_complex channelsplit out.mkv
425 will create an output Matroska file with two audio streams, one containing only
426 the left channel and the other the right channel.
428 To split a 5.1 WAV file into per-channel files
430 avconv -i in.wav -filter_complex
431 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
432 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
433 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
438 Remap input channels to new locations.
440 This filter accepts the following named parameters:
443 Channel layout of the output stream.
446 Map channels from input to output. The argument is a '|'-separated list of
447 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
448 @var{in_channel} form. @var{in_channel} can be either the name of the input
449 channel (e.g. FL for front left) or its index in the input channel layout.
450 @var{out_channel} is the name of the output channel or its index in the output
451 channel layout. If @var{out_channel} is not given then it is implicitly an
452 index, starting with zero and increasing by one for each mapping.
455 If no mapping is present, the filter will implicitly map input channels to
456 output channels preserving index.
458 For example, assuming a 5.1+downmix input MOV file
460 avconv -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
462 will create an output WAV file tagged as stereo from the downmix channels of
465 To fix a 5.1 WAV improperly encoded in AAC's native channel order
467 avconv -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
471 Join multiple input streams into one multi-channel stream.
473 The filter accepts the following named parameters:
477 Number of input streams. Defaults to 2.
480 Desired output channel layout. Defaults to stereo.
483 Map channels from inputs to output. The argument is a '|'-separated list of
484 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
485 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
486 can be either the name of the input channel (e.g. FL for front left) or its
487 index in the specified input stream. @var{out_channel} is the name of the output
491 The filter will attempt to guess the mappings when those are not specified
492 explicitly. It does so by first trying to find an unused matching input channel
493 and if that fails it picks the first unused input channel.
495 E.g. to join 3 inputs (with properly set channel layouts)
497 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
500 To build a 5.1 output from 6 single-channel streams:
502 avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
503 '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'
508 Convert the audio sample format, sample rate and channel layout. This filter is
509 not meant to be used directly, it is inserted automatically by libavfilter
510 whenever conversion is needed. Use the @var{aformat} filter to force a specific
515 Adjust the input audio volume.
517 The filter accepts the following named parameters:
521 Expresses how the audio volume will be increased or decreased.
523 Output values are clipped to the maximum value.
525 The output audio volume is given by the relation:
527 @var{output_volume} = @var{volume} * @var{input_volume}
530 Default value for @var{volume} is 1.0.
533 Mathematical precision.
535 This determines which input sample formats will be allowed, which affects the
536 precision of the volume scaling.
540 8-bit fixed-point; limits input sample format to U8, S16, and S32.
542 32-bit floating-point; limits input sample format to FLT. (default)
544 64-bit floating-point; limits input sample format to DBL.
552 Halve the input audio volume:
556 volume=volume=-6.0206dB
560 Increase input audio power by 6 decibels using fixed-point precision:
562 volume=volume=6dB:precision=fixed
566 @c man end AUDIO FILTERS
568 @chapter Audio Sources
569 @c man begin AUDIO SOURCES
571 Below is a description of the currently available audio sources.
575 Null audio source, never return audio frames. It is mainly useful as a
576 template and to be employed in analysis / debugging tools.
578 It accepts as optional parameter a string of the form
579 @var{sample_rate}:@var{channel_layout}.
581 @var{sample_rate} specify the sample rate, and defaults to 44100.
583 @var{channel_layout} specify the channel layout, and can be either an
584 integer or a string representing a channel layout. The default value
585 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
587 Check the channel_layout_map definition in
588 @file{libavutil/channel_layout.c} for the mapping between strings and
589 channel layout values.
591 Follow some examples:
593 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
601 Buffer audio frames, and make them available to the filter chain.
603 This source is not intended to be part of user-supplied graph descriptions but
604 for insertion by calling programs through the interface defined in
605 @file{libavfilter/buffersrc.h}.
607 It accepts the following named parameters:
611 Timebase which will be used for timestamps of submitted frames. It must be
612 either a floating-point number or in @var{numerator}/@var{denominator} form.
618 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
621 Channel layout of the audio data, in the form that can be accepted by
622 @code{av_get_channel_layout()}.
625 All the parameters need to be explicitly defined.
627 @c man end AUDIO SOURCES
630 @c man begin AUDIO SINKS
632 Below is a description of the currently available audio sinks.
636 Null audio sink, do absolutely nothing with the input audio. It is
637 mainly useful as a template and to be employed in analysis / debugging
641 This sink is intended for programmatic use. Frames that arrive on this sink can
642 be retrieved by the calling program using the interface defined in
643 @file{libavfilter/buffersink.h}.
645 This filter accepts no parameters.
647 @c man end AUDIO SINKS
649 @chapter Video Filters
650 @c man begin VIDEO FILTERS
652 When you configure your Libav build, you can disable any of the
653 existing filters using --disable-filters.
654 The configure output will show the video filters included in your
657 Below is a description of the currently available video filters.
661 Detect frames that are (almost) completely black. Can be useful to
662 detect chapter transitions or commercials. Output lines consist of
663 the frame number of the detected frame, the percentage of blackness,
664 the position in the file if known or -1 and the timestamp in seconds.
666 In order to display the output lines, you need to set the loglevel at
667 least to the AV_LOG_INFO value.
669 The filter accepts the following options:
674 The percentage of the pixels that have to be below the threshold, defaults to
678 Threshold below which a pixel value is considered black, defaults to 32.
684 Apply boxblur algorithm to the input video.
686 This filter accepts the following options:
699 Chroma and alpha parameters are optional, if not specified they default
700 to the corresponding values set for @var{luma_radius} and
703 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
704 the radius in pixels of the box used for blurring the corresponding
705 input plane. They are expressions, and can contain the following
709 the input width and height in pixels
712 the input chroma image width and height in pixels
715 horizontal and vertical chroma subsample values. For example for the
716 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
719 The radius must be a non-negative number, and must not be greater than
720 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
721 and of @code{min(cw,ch)/2} for the chroma planes.
723 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
724 how many times the boxblur filter is applied to the corresponding
727 Some examples follow:
732 Apply a boxblur filter with luma, chroma, and alpha radius
735 boxblur=luma_radius=2:luma_power=1
739 Set luma radius to 2, alpha and chroma radius to 0
745 Set luma and chroma radius to a fraction of the video dimension
747 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
754 Copy the input source unchanged to the output. Mainly useful for
759 Crop the input video to given dimensions.
761 This filter accepts the following options:
766 Width of the output video.
769 Height of the output video.
772 Horizontal position, in the input video, of the left edge of the output video.
775 Vertical position, in the input video, of the top edge of the output video.
779 The parameters are expressions containing the following constants:
783 the corresponding mathematical approximated values for e
784 (euler number), pi (greek PI), PHI (golden ratio)
787 the computed values for @var{x} and @var{y}. They are evaluated for
791 the input width and height
794 same as @var{in_w} and @var{in_h}
797 the output (cropped) width and height
800 same as @var{out_w} and @var{out_h}
803 the number of input frame, starting from 0
806 timestamp expressed in seconds, NAN if the input timestamp is unknown
810 The @var{out_w} and @var{out_h} parameters specify the expressions for
811 the width and height of the output (cropped) video. They are
812 evaluated just at the configuration of the filter.
814 The default value of @var{out_w} is "in_w", and the default value of
815 @var{out_h} is "in_h".
817 The expression for @var{out_w} may depend on the value of @var{out_h},
818 and the expression for @var{out_h} may depend on @var{out_w}, but they
819 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
820 evaluated after @var{out_w} and @var{out_h}.
822 The @var{x} and @var{y} parameters specify the expressions for the
823 position of the top-left corner of the output (non-cropped) area. They
824 are evaluated for each frame. If the evaluated value is not valid, it
825 is approximated to the nearest valid value.
827 The default value of @var{x} is "(in_w-out_w)/2", and the default
828 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
829 the center of the input image.
831 The expression for @var{x} may depend on @var{y}, and the expression
832 for @var{y} may depend on @var{x}.
834 Follow some examples:
836 # crop the central input area with size 100x100
837 crop=out_w=100:out_h=100
839 # crop the central input area with size 2/3 of the input video
840 "crop=out_w=2/3*in_w:out_h=2/3*in_h"
842 # crop the input video central square
845 # delimit the rectangle with the top-left corner placed at position
846 # 100:100 and the right-bottom corner corresponding to the right-bottom
847 # corner of the input image.
848 crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
850 # crop 10 pixels from the left and right borders, and 20 pixels from
851 # the top and bottom borders
852 "crop=out_w=in_w-2*10:out_h=in_h-2*20"
854 # keep only the bottom right quarter of the input image
855 "crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
857 # crop height for getting Greek harmony
858 "crop=out_w=in_w:out_h=1/PHI*in_w"
861 "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)"
863 # erratic camera effect depending on timestamp
864 "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)"
866 # set x depending on the value of y
867 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
872 Auto-detect crop size.
874 Calculate necessary cropping parameters and prints the recommended
875 parameters through the logging system. The detected dimensions
876 correspond to the non-black area of the input video.
878 This filter accepts the following options:
883 Threshold, which can be optionally specified from nothing (0) to
884 everything (255), defaults to 24.
887 Value which the width/height should be divisible by, defaults to
888 16. The offset is automatically adjusted to center the video. Use 2 to
889 get only even dimensions (needed for 4:2:2 video). 16 is best when
890 encoding to most video codecs.
893 Counter that determines after how many frames cropdetect will reset
894 the previously detected largest video area and start over to detect
895 the current optimal crop area. Defaults to 0.
897 This can be useful when channel logos distort the video area. 0
898 indicates never reset and return the largest area encountered during
904 Suppress a TV station logo by a simple interpolation of the surrounding
905 pixels. Just set a rectangle covering the logo and watch it disappear
906 (and sometimes something even uglier appear - your mileage may vary).
908 This filter accepts the following options:
912 Specify the top left corner coordinates of the logo. They must be
916 Specify the width and height of the logo to clear. They must be
920 Specify the thickness of the fuzzy edge of the rectangle (added to
921 @var{w} and @var{h}). The default value is 4.
924 When set to 1, a green rectangle is drawn on the screen to simplify
925 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
926 @var{band} is set to 4. The default value is 0.
930 Some examples follow.
935 Set a rectangle covering the area with top left corner coordinates 0,0
936 and size 100x77, setting a band of size 10:
938 delogo=x=0:y=0:w=100:h=77:band=10
945 Draw a colored box on the input image.
947 This filter accepts the following options:
952 Specify the top left corner coordinates of the box. Default to 0.
955 Specify the width and height of the box, if 0 they are interpreted as
956 the input width and height. Default to 0.
959 Specify the color of the box to write, it can be the name of a color
960 (case insensitive match) or a 0xRRGGBB[AA] sequence.
963 Follow some examples:
965 # draw a black box around the edge of the input image
968 # draw a box with color red and an opacity of 50%
969 drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
974 Draw text string or text from specified file on top of video using the
977 To enable compilation of this filter you need to configure Libav with
978 @code{--enable-libfreetype}.
980 The filter also recognizes strftime() sequences in the provided text
981 and expands them accordingly. Check the documentation of strftime().
983 The description of the accepted parameters follows.
988 The font file to be used for drawing text. Path must be included.
989 This parameter is mandatory.
992 The text string to be drawn. The text must be a sequence of UTF-8
994 This parameter is mandatory if no file is specified with the parameter
998 A text file containing text to be drawn. The text must be a sequence
999 of UTF-8 encoded characters.
1001 This parameter is mandatory if no text string is specified with the
1002 parameter @var{text}.
1004 If both text and textfile are specified, an error is thrown.
1007 The offsets where text will be drawn within the video frame.
1008 Relative to the top/left border of the output image.
1009 They accept expressions similar to the @ref{overlay} filter:
1013 the computed values for @var{x} and @var{y}. They are evaluated for
1016 @item main_w, main_h
1017 main input width and height
1020 same as @var{main_w} and @var{main_h}
1022 @item text_w, text_h
1023 rendered text width and height
1026 same as @var{text_w} and @var{text_h}
1029 the number of frames processed, starting from 0
1032 timestamp expressed in seconds, NAN if the input timestamp is unknown
1036 The default value of @var{x} and @var{y} is 0.
1039 The font size to be used for drawing text.
1040 The default value of @var{fontsize} is 16.
1043 The color to be used for drawing fonts.
1044 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1045 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1046 The default value of @var{fontcolor} is "black".
1049 The color to be used for drawing box around text.
1050 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1051 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1052 The default value of @var{boxcolor} is "white".
1055 Used to draw a box around text using background color.
1056 Value should be either 1 (enable) or 0 (disable).
1057 The default value of @var{box} is 0.
1059 @item shadowx, shadowy
1060 The x and y offsets for the text shadow position with respect to the
1061 position of the text. They can be either positive or negative
1062 values. Default value for both is "0".
1065 The color to be used for drawing a shadow behind the drawn text. It
1066 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1067 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1068 The default value of @var{shadowcolor} is "black".
1071 Flags to be used for loading the fonts.
1073 The flags map the corresponding flags supported by libfreetype, and are
1074 a combination of the following values:
1081 @item vertical_layout
1082 @item force_autohint
1085 @item ignore_global_advance_width
1087 @item ignore_transform
1094 Default value is "render".
1096 For more information consult the documentation for the FT_LOAD_*
1100 The size in number of spaces to use for rendering the tab.
1104 If true, check and fix text coords to avoid clipping.
1107 For example the command:
1109 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1112 will draw "Test Text" with font FreeSerif, using the default values
1113 for the optional parameters.
1117 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1118 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1121 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
1122 and y=50 (counting from the top-left corner of the screen), text is
1123 yellow with a red box around it. Both the text and the box have an
1126 Note that the double quotes are not necessary if spaces are not used
1127 within the parameter list.
1129 For more information about libfreetype, check:
1130 @url{http://www.freetype.org/}.
1134 Apply fade-in/out effect to input video.
1136 This filter accepts the following options:
1141 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
1145 The number of the start frame for starting to apply the fade effect.
1148 The number of frames for which the fade effect has to last. At the end of the
1149 fade-in effect the output video will have the same intensity as the input video,
1150 at the end of the fade-out transition the output video will be completely black.
1154 A few usage examples follow, usable too as test scenarios.
1156 # fade in first 30 frames of video
1157 fade=type=in:nb_frames=30
1159 # fade out last 45 frames of a 200-frame video
1160 fade=type=out:start_frame=155:nb_frames=45
1162 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1163 fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
1165 # make first 5 frames black, then fade in from frame 5-24
1166 fade=type=in:start_frame=5:nb_frames=20
1171 Transform the field order of the input video.
1173 This filter accepts the following options:
1178 Output field order. Valid values are @var{tff} for top field first or @var{bff}
1179 for bottom field first.
1182 Default value is "tff".
1184 Transformation is achieved by shifting the picture content up or down
1185 by one line, and filling the remaining line with appropriate picture content.
1186 This method is consistent with most broadcast field order converters.
1188 If the input video is not flagged as being interlaced, or it is already
1189 flagged as being of the required output field order then this filter does
1190 not alter the incoming video.
1192 This filter is very useful when converting to or from PAL DV material,
1193 which is bottom field first.
1197 ./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
1202 Buffer input images and send them when they are requested.
1204 This filter is mainly useful when auto-inserted by the libavfilter
1207 The filter does not take parameters.
1211 Convert the input video to one of the specified pixel formats.
1212 Libavfilter will try to pick one that is supported for the input to
1215 This filter accepts the following parameters:
1219 A '|'-separated list of pixel format names, for example
1220 "pix_fmts=yuv420p|monow|rgb24".
1224 Some examples follow:
1226 # convert the input video to the format "yuv420p"
1227 format=pix_fmts=yuv420p
1229 # convert the input video to any of the formats in the list
1230 format=pix_fmts=yuv420p|yuv444p|yuv410p
1235 Convert the video to specified constant framerate by duplicating or dropping
1236 frames as necessary.
1238 This filter accepts the following named parameters:
1242 Desired output framerate.
1249 Apply a frei0r effect to the input video.
1251 To enable compilation of this filter you need to install the frei0r
1252 header and configure Libav with --enable-frei0r.
1254 This filter accepts the following options:
1259 The name to the frei0r effect to load. If the environment variable
1260 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
1261 directories specified by the colon separated list in @env{FREIOR_PATH},
1262 otherwise in the standard frei0r paths, which are in this order:
1263 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
1264 @file{/usr/lib/frei0r-1/}.
1267 A '|'-separated list of parameters to pass to the frei0r effect.
1271 A frei0r effect parameter can be a boolean (whose values are specified
1272 with "y" and "n"), a double, a color (specified by the syntax
1273 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1274 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1275 description), a position (specified by the syntax @var{X}/@var{Y},
1276 @var{X} and @var{Y} being float numbers) and a string.
1278 The number and kind of parameters depend on the loaded effect. If an
1279 effect parameter is not specified the default value is set.
1281 Some examples follow:
1283 # apply the distort0r effect, set the first two double parameters
1284 frei0r=filter_name=distort0r:filter_params=0.5|0.01
1286 # apply the colordistance effect, takes a color as first parameter
1287 frei0r=colordistance:0.2/0.3/0.4
1288 frei0r=colordistance:violet
1289 frei0r=colordistance:0x112233
1291 # apply the perspective effect, specify the top left and top right
1293 frei0r=perspective:0.2/0.2|0.8/0.2
1296 For more information see:
1297 @url{http://piksel.org/frei0r}
1301 Fix the banding artifacts that are sometimes introduced into nearly flat
1302 regions by truncation to 8bit colordepth.
1303 Interpolate the gradients that should go where the bands are, and
1306 This filter is designed for playback only. Do not use it prior to
1307 lossy compression, because compression tends to lose the dither and
1308 bring back the bands.
1310 This filter accepts the following options:
1315 The maximum amount by which the filter will change any one pixel. Also the
1316 threshold for detecting nearly flat regions. Acceptable values range from .51 to
1317 64, default value is 1.2, out-of-range values will be clipped to the valid
1321 The neighborhood to fit the gradient to. A larger radius makes for smoother
1322 gradients, but also prevents the filter from modifying the pixels near detailed
1323 regions. Acceptable values are 8-32, default value is 16, out-of-range values
1324 will be clipped to the valid range.
1329 # default parameters
1330 gradfun=strength=1.2:radius=16
1338 Flip the input video horizontally.
1340 For example to horizontally flip the input video with @command{avconv}:
1342 avconv -i in.avi -vf "hflip" out.avi
1347 High precision/quality 3d denoise filter. This filter aims to reduce
1348 image noise producing smooth images and making still images really
1349 still. It should enhance compressibility.
1351 It accepts the following optional parameters:
1355 a non-negative float number which specifies spatial luma strength,
1358 @item chroma_spatial
1359 a non-negative float number which specifies spatial chroma strength,
1360 defaults to 3.0*@var{luma_spatial}/4.0
1363 a float number which specifies luma temporal strength, defaults to
1364 6.0*@var{luma_spatial}/4.0
1367 a float number which specifies chroma temporal strength, defaults to
1368 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1373 Simple interlacing filter from progressive contents. This interleaves upper (or
1374 lower) lines from odd frames with lower (or upper) lines from even frames,
1375 halving the frame rate and preserving image height.
1378 Original Original New Frame
1379 Frame 'j' Frame 'j+1' (tff)
1380 ========== =========== ==================
1381 Line 0 --------------------> Frame 'j' Line 0
1382 Line 1 Line 1 ----> Frame 'j+1' Line 1
1383 Line 2 ---------------------> Frame 'j' Line 2
1384 Line 3 Line 3 ----> Frame 'j+1' Line 3
1386 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
1389 It accepts the following optional parameters:
1393 determines whether the interlaced frame is taken from the even (tff - default)
1394 or odd (bff) lines of the progressive frame.
1397 Enable (default) or disable the vertical lowpass filter to avoid twitter
1398 interlacing and reduce moire patterns.
1401 @section lut, lutrgb, lutyuv
1403 Compute a look-up table for binding each pixel component input value
1404 to an output value, and apply it to input video.
1406 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1407 to an RGB input video.
1409 These filters accept the following options:
1411 @item @var{c0} (first pixel component)
1412 @item @var{c1} (second pixel component)
1413 @item @var{c2} (third pixel component)
1414 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
1416 @item @var{r} (red component)
1417 @item @var{g} (green component)
1418 @item @var{b} (blue component)
1419 @item @var{a} (alpha component)
1421 @item @var{y} (Y/luminance component)
1422 @item @var{u} (U/Cb component)
1423 @item @var{v} (V/Cr component)
1426 Each of them specifies the expression to use for computing the lookup table for
1427 the corresponding pixel component values.
1429 The exact component associated to each of the @var{c*} options depends on the
1432 The @var{lut} filter requires either YUV or RGB pixel formats in input,
1433 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
1435 The expressions can contain the following constants and functions:
1439 the corresponding mathematical approximated values for e
1440 (euler number), pi (greek PI), PHI (golden ratio)
1443 the input width and height
1446 input value for the pixel component
1449 the input value clipped in the @var{minval}-@var{maxval} range
1452 maximum value for the pixel component
1455 minimum value for the pixel component
1458 the negated value for the pixel component value clipped in the
1459 @var{minval}-@var{maxval} range , it corresponds to the expression
1460 "maxval-clipval+minval"
1463 the computed value in @var{val} clipped in the
1464 @var{minval}-@var{maxval} range
1466 @item gammaval(gamma)
1467 the computed gamma correction value of the pixel component value
1468 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1470 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1474 All expressions default to "val".
1476 Some examples follow:
1478 # negate input video
1479 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1480 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1482 # the above is the same as
1483 lutrgb="r=negval:g=negval:b=negval"
1484 lutyuv="y=negval:u=negval:v=negval"
1489 # remove chroma components, turns the video into a graytone image
1490 lutyuv="u=128:v=128"
1492 # apply a luma burning effect
1495 # remove green and blue components
1498 # set a constant alpha channel value on input
1499 format=rgba,lutrgb=a="maxval-minval/2"
1501 # correct luminance gamma by a 0.5 factor
1502 lutyuv=y=gammaval(0.5)
1509 This filter accepts an integer in input, if non-zero it negates the
1510 alpha component (if available). The default value in input is 0.
1514 Force libavfilter not to use any of the specified pixel formats for the
1515 input to the next filter.
1517 This filter accepts the following parameters:
1521 A '|'-separated list of pixel format names, for example
1522 "pix_fmts=yuv420p|monow|rgb24".
1526 Some examples follow:
1528 # force libavfilter to use a format different from "yuv420p" for the
1529 # input to the vflip filter
1530 noformat=pix_fmts=yuv420p,vflip
1532 # convert the input video to any of the formats not contained in the list
1533 noformat=yuv420p|yuv444p|yuv410p
1538 Pass the video source unchanged to the output.
1542 Apply video transform using libopencv.
1544 To enable this filter install libopencv library and headers and
1545 configure Libav with --enable-libopencv.
1547 This filter accepts the following parameters:
1552 The name of the libopencv filter to apply.
1555 The parameters to pass to the libopencv filter. If not specified the default
1560 Refer to the official libopencv documentation for more precise
1562 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1564 Follows the list of supported libopencv filters.
1569 Dilate an image by using a specific structuring element.
1570 This filter corresponds to the libopencv function @code{cvDilate}.
1572 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
1574 @var{struct_el} represents a structuring element, and has the syntax:
1575 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1577 @var{cols} and @var{rows} represent the number of columns and rows of
1578 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1579 point, and @var{shape} the shape for the structuring element, and
1580 can be one of the values "rect", "cross", "ellipse", "custom".
1582 If the value for @var{shape} is "custom", it must be followed by a
1583 string of the form "=@var{filename}". The file with name
1584 @var{filename} is assumed to represent a binary image, with each
1585 printable character corresponding to a bright pixel. When a custom
1586 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1587 or columns and rows of the read file are assumed instead.
1589 The default value for @var{struct_el} is "3x3+0x0/rect".
1591 @var{nb_iterations} specifies the number of times the transform is
1592 applied to the image, and defaults to 1.
1594 Follow some example:
1596 # use the default values
1599 # dilate using a structuring element with a 5x5 cross, iterate two times
1600 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
1602 # read the shape from the file diamond.shape, iterate two times
1603 # the file diamond.shape may contain a pattern of characters like this:
1609 # the specified cols and rows are ignored (but not the anchor point coordinates)
1610 ocv=dilate:0x0+2x2/custom=diamond.shape|2
1615 Erode an image by using a specific structuring element.
1616 This filter corresponds to the libopencv function @code{cvErode}.
1618 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1619 with the same syntax and semantics as the @ref{dilate} filter.
1623 Smooth the input video.
1625 The filter takes the following parameters:
1626 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
1628 @var{type} is the type of smooth filter to apply, and can be one of
1629 the following values: "blur", "blur_no_scale", "median", "gaussian",
1630 "bilateral". The default value is "gaussian".
1632 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1633 parameters whose meanings depend on smooth type. @var{param1} and
1634 @var{param2} accept integer positive values or 0, @var{param3} and
1635 @var{param4} accept float values.
1637 The default value for @var{param1} is 3, the default value for the
1638 other parameters is 0.
1640 These parameters correspond to the parameters assigned to the
1641 libopencv function @code{cvSmooth}.
1646 Overlay one video on top of another.
1648 It takes two inputs and one output, the first input is the "main"
1649 video on which the second input is overlayed.
1651 This filter accepts the following parameters:
1656 The horizontal position of the left edge of the overlaid video on the main video.
1659 The vertical position of the top edge of the overlaid video on the main video.
1663 The parameters are expressions containing the following parameters:
1666 @item main_w, main_h
1667 main input width and height
1670 same as @var{main_w} and @var{main_h}
1672 @item overlay_w, overlay_h
1673 overlay input width and height
1676 same as @var{overlay_w} and @var{overlay_h}
1679 Be aware that frames are taken from each input video in timestamp
1680 order, hence, if their initial timestamps differ, it is a a good idea
1681 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1682 have them begin in the same zero timestamp, as it does the example for
1683 the @var{movie} filter.
1685 Follow some examples:
1687 # draw the overlay at 10 pixels from the bottom right
1688 # corner of the main video.
1689 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
1691 # insert a transparent PNG logo in the bottom left corner of the input
1692 avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
1694 # insert 2 different transparent PNG logos (second logo on bottom
1696 avconv -i input -i logo1 -i logo2 -filter_complex
1697 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
1699 # add a transparent color layer on top of the main video,
1700 # WxH specifies the size of the main input to the overlay filter
1701 color=red@.3:WxH [over]; [in][over] overlay [out]
1704 You can chain together more overlays but the efficiency of such
1705 approach is yet to be tested.
1709 Add paddings to the input image, and places the original input at the
1710 given coordinates @var{x}, @var{y}.
1712 This filter accepts the following parameters:
1717 Specify the size of the output image with the paddings added. If the
1718 value for @var{width} or @var{height} is 0, the corresponding input size
1719 is used for the output.
1721 The @var{width} expression can reference the value set by the
1722 @var{height} expression, and vice versa.
1724 The default value of @var{width} and @var{height} is 0.
1728 Specify the offsets where to place the input image in the padded area
1729 with respect to the top/left border of the output image.
1731 The @var{x} expression can reference the value set by the @var{y}
1732 expression, and vice versa.
1734 The default value of @var{x} and @var{y} is 0.
1738 Specify the color of the padded area, it can be the name of a color
1739 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1741 The default value of @var{color} is "black".
1745 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1746 expressions containing the following constants:
1750 the corresponding mathematical approximated values for e
1751 (euler number), pi (greek PI), phi (golden ratio)
1754 the input video width and height
1757 same as @var{in_w} and @var{in_h}
1760 the output width and height, that is the size of the padded area as
1761 specified by the @var{width} and @var{height} expressions
1764 same as @var{out_w} and @var{out_h}
1767 x and y offsets as specified by the @var{x} and @var{y}
1768 expressions, or NAN if not yet specified
1771 input display aspect ratio, same as @var{iw} / @var{ih}
1774 horizontal and vertical chroma subsample values. For example for the
1775 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1778 Some examples follow:
1781 # Add paddings with color "violet" to the input video. Output video
1782 # size is 640x480, the top-left corner of the input video is placed at
1784 pad=width=640:height=480:x=0:y=40:color=violet
1786 # pad the input to get an output with dimensions increased bt 3/2,
1787 # and put the input video at the center of the padded area
1788 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1790 # pad the input to get a squared output with size equal to the maximum
1791 # value between the input width and height, and put the input video at
1792 # the center of the padded area
1793 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1795 # pad the input to get a final w/h ratio of 16:9
1796 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1798 # double output size and put the input video in the bottom-right
1799 # corner of the output padded area
1800 pad="2*iw:2*ih:ow-iw:oh-ih"
1803 @section pixdesctest
1805 Pixel format descriptor test filter, mainly useful for internal
1806 testing. The output video should be equal to the input video.
1810 format=monow, pixdesctest
1813 can be used to test the monowhite pixel format descriptor definition.
1817 Scale the input video and/or convert the image format.
1819 This filter accepts the following options:
1827 Output video height.
1831 The parameters @var{w} and @var{h} are expressions containing
1832 the following constants:
1836 the corresponding mathematical approximated values for e
1837 (euler number), pi (greek PI), phi (golden ratio)
1840 the input width and height
1843 same as @var{in_w} and @var{in_h}
1846 the output (cropped) width and height
1849 same as @var{out_w} and @var{out_h}
1852 input display aspect ratio, same as @var{iw} / @var{ih}
1855 input sample aspect ratio
1858 horizontal and vertical chroma subsample values. For example for the
1859 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1862 If the input image format is different from the format requested by
1863 the next filter, the scale filter will convert the input to the
1866 If the value for @var{w} or @var{h} is 0, the respective input
1867 size is used for the output.
1869 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
1870 respective output size, a value that maintains the aspect ratio of the input
1873 The default value of @var{w} and @var{h} is 0.
1875 Some examples follow:
1877 # scale the input video to a size of 200x100.
1880 # scale the input to 2x
1882 # the above is the same as
1885 # scale the input to half size
1888 # increase the width, and set the height to the same size
1891 # seek for Greek harmony
1895 # increase the height, and set the width to 3/2 of the height
1896 scale=w=3/2*oh:h=3/5*ih
1898 # increase the size, but make the size a multiple of the chroma
1899 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1901 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1902 scale=w='min(500\, iw*3/2):h=-1'
1906 Select frames to pass in output.
1908 This filter accepts the following options:
1913 An expression, which is evaluated for each input frame. If the expression is
1914 evaluated to a non-zero value, the frame is selected and passed to the output,
1915 otherwise it is discarded.
1919 The expression can contain the following constants:
1932 the sequential number of the filtered frame, starting from 0
1935 the sequential number of the selected frame, starting from 0
1937 @item prev_selected_n
1938 the sequential number of the last selected frame, NAN if undefined
1941 timebase of the input timestamps
1944 the PTS (Presentation TimeStamp) of the filtered video frame,
1945 expressed in @var{TB} units, NAN if undefined
1948 the PTS (Presentation TimeStamp) of the filtered video frame,
1949 expressed in seconds, NAN if undefined
1952 the PTS of the previously filtered video frame, NAN if undefined
1954 @item prev_selected_pts
1955 the PTS of the last previously filtered video frame, NAN if undefined
1957 @item prev_selected_t
1958 the PTS of the last previously selected video frame, NAN if undefined
1961 the PTS of the first video frame in the video, NAN if undefined
1964 the time of the first video frame in the video, NAN if undefined
1967 the type of the filtered frame, can assume one of the following
1979 @item interlace_type
1980 the frame interlace type, can assume one of the following values:
1983 the frame is progressive (not interlaced)
1985 the frame is top-field-first
1987 the frame is bottom-field-first
1991 1 if the filtered frame is a key-frame, 0 otherwise
1995 The default value of the select expression is "1".
1997 Some examples follow:
2000 # select all frames in input
2003 # the above is the same as:
2009 # select only I-frames
2010 select='expr=eq(pict_type\,I)'
2012 # select one frame every 100
2013 select='not(mod(n\,100))'
2015 # select only frames contained in the 10-20 time interval
2016 select='gte(t\,10)*lte(t\,20)'
2018 # select only I frames contained in the 10-20 time interval
2019 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2021 # select frames with a minimum distance of 10 seconds
2022 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2028 Set the Display Aspect Ratio for the filter output video.
2030 This is done by changing the specified Sample (aka Pixel) Aspect
2031 Ratio, according to the following equation:
2032 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2034 Keep in mind that this filter does not modify the pixel dimensions of
2035 the video frame. Also the display aspect ratio set by this filter may
2036 be changed by later filters in the filterchain, e.g. in case of
2037 scaling or if another "setdar" or a "setsar" filter is applied.
2039 This filter accepts the following options:
2044 Output display aspect ratio, as a rational or a decimal number.
2048 For example to change the display aspect ratio to 16:9, specify:
2051 # the above is equivalent to
2055 See also the @ref{setsar} filter documentation.
2059 Change the PTS (presentation timestamp) of the input video frames.
2061 This filter accepts the following options:
2066 The expression which is evaluated for each frame to construct its timestamp.
2070 The expression is evaluated through the eval API and can contain the following
2075 the presentation timestamp in input
2087 the count of the input frame, starting from 0.
2090 the PTS of the first video frame
2093 tell if the current frame is interlaced
2102 wallclock (RTC) time in microseconds
2105 wallclock (RTC) time at the start of the movie in microseconds
2109 Some examples follow:
2112 # start counting PTS from zero
2113 setpts=expr=PTS-STARTPTS
2124 # fixed rate 25 fps with some jitter
2125 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2127 # generate timestamps from a "live source" and rebase onto the current timebase
2128 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
2134 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2136 Note that as a consequence of the application of this filter, the
2137 output display aspect ratio will change according to the following
2139 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2141 Keep in mind that the sample aspect ratio set by this filter may be
2142 changed by later filters in the filterchain, e.g. if another "setsar"
2143 or a "setdar" filter is applied.
2145 This filter accepts the following options:
2150 Output sample aspect ratio, as a rational or decimal number.
2154 For example to change the sample aspect ratio to 10:11, specify:
2161 Set the timebase to use for the output frames timestamps.
2162 It is mainly useful for testing timebase configuration.
2164 This filter accepts the following options:
2169 The expression which is evaluated into the output timebase.
2173 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
2174 default timebase), and "intb" (the input timebase).
2176 The default value for the input is "intb".
2178 Follow some examples.
2181 # set the timebase to 1/25
2184 # set the timebase to 1/10
2187 #set the timebase to 1001/1000
2190 #set the timebase to 2*intb
2193 #set the default timebase value
2199 Show a line containing various information for each input video frame.
2200 The input video is not modified.
2202 The shown line contains a sequence of key/value pairs of the form
2203 @var{key}:@var{value}.
2205 A description of each shown parameter follows:
2209 sequential number of the input frame, starting from 0
2212 Presentation TimeStamp of the input frame, expressed as a number of
2213 time base units. The time base unit depends on the filter input pad.
2216 Presentation TimeStamp of the input frame, expressed as a number of
2220 position of the frame in the input stream, -1 if this information in
2221 unavailable and/or meaningless (for example in case of synthetic video)
2227 sample aspect ratio of the input frame, expressed in the form
2231 size of the input frame, expressed in the form
2232 @var{width}x@var{height}
2235 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2236 for bottom field first)
2239 1 if the frame is a key frame, 0 otherwise
2242 picture type of the input frame ("I" for an I-frame, "P" for a
2243 P-frame, "B" for a B-frame, "?" for unknown type).
2244 Check also the documentation of the @code{AVPictureType} enum and of
2245 the @code{av_get_picture_type_char} function defined in
2246 @file{libavutil/avutil.h}.
2249 Adler-32 checksum of all the planes of the input frame
2251 @item plane_checksum
2252 Adler-32 checksum of each plane of the input frame, expressed in the form
2253 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2258 Split input video into several identical outputs.
2260 The filter accepts a single parameter which specifies the number of outputs. If
2261 unspecified, it defaults to 2.
2265 avconv -i INPUT -filter_complex split=5 OUTPUT
2267 will create 5 copies of the input video.
2271 Transpose rows with columns in the input video and optionally flip it.
2273 This filter accepts the following options:
2278 The direction of the transpose.
2282 The direction can assume the following values:
2286 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2294 Rotate by 90 degrees clockwise, that is:
2302 Rotate by 90 degrees counterclockwise, that is:
2310 Rotate by 90 degrees clockwise and vertically flip, that is:
2319 Trim the input so that the output contains one continuous subpart of the input.
2321 This filter accepts the following options:
2324 Timestamp (in seconds) of the start of the kept section. I.e. the frame with the
2325 timestamp @var{start} will be the first frame in the output.
2328 Timestamp (in seconds) of the first frame that will be dropped. I.e. the frame
2329 immediately preceding the one with the timestamp @var{end} will be the last
2330 frame in the output.
2333 Same as @var{start}, except this option sets the start timestamp in timebase
2334 units instead of seconds.
2337 Same as @var{end}, except this option sets the end timestamp in timebase units
2341 Maximum duration of the output in seconds.
2344 Number of the first frame that should be passed to output.
2347 Number of the first frame that should be dropped.
2350 Note that the first two sets of the start/end options and the @option{duration}
2351 option look at the frame timestamp, while the _frame variants simply count the
2352 frames that pass through the filter. Also note that this filter does not modify
2353 the timestamps. If you wish that the output timestamps start at zero, insert a
2354 setpts filter after the trim filter.
2356 If multiple start or end options are set, this filter tries to be greedy and
2357 keep all the frames that match at least one of the specified constraints. To keep
2358 only the part that matches all the constraints at once, chain multiple trim
2361 The defaults are such that all the input is kept. So it is possible to set e.g.
2362 just the end values to keep everything before the specified time.
2367 drop everything except the second minute of input
2369 avconv -i INPUT -vf trim=60:120
2373 keep only the first second
2375 avconv -i INPUT -vf trim=duration=1
2381 Sharpen or blur the input video.
2383 It accepts the following parameters:
2388 Set the luma matrix horizontal size. It can be an integer between 3
2389 and 13, default value is 5.
2392 Set the luma matrix vertical size. It can be an integer between 3
2393 and 13, default value is 5.
2396 Set the luma effect strength. It can be a float number between -2.0
2397 and 5.0, default value is 1.0.
2399 @item chroma_msize_x
2400 Set the chroma matrix horizontal size. It can be an integer between 3
2401 and 13, default value is 5.
2403 @item chroma_msize_y
2404 Set the chroma matrix vertical size. It can be an integer between 3
2405 and 13, default value is 5.
2408 Set the chroma effect strength. It can be a float number between -2.0
2409 and 5.0, default value is 0.0.
2413 Negative values for the amount will blur the input video, while positive
2414 values will sharpen. All parameters are optional and default to the
2415 equivalent of the string '5:5:1.0:5:5:0.0'.
2418 # Strong luma sharpen effect parameters
2419 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
2421 # Strong blur of both luma and chroma parameters
2422 unsharp=7:7:-2:7:7:-2
2424 # Use the default values with @command{avconv}
2425 ./avconv -i in.avi -vf "unsharp" out.mp4
2430 Flip the input video vertically.
2433 ./avconv -i in.avi -vf "vflip" out.avi
2438 Deinterlace the input video ("yadif" means "yet another deinterlacing
2441 This filter accepts the following options:
2446 The interlacing mode to adopt, accepts one of the following values:
2450 output 1 frame for each frame
2452 output 1 frame for each field
2454 like 0 but skips spatial interlacing check
2456 like 1 but skips spatial interlacing check
2462 The picture field parity assumed for the input interlaced video, accepts one of
2463 the following values:
2467 assume top field first
2469 assume bottom field first
2471 enable automatic detection
2474 Default value is -1.
2475 If interlacing is unknown or decoder does not export this information,
2476 top field first will be assumed.
2479 Whether deinterlacer should trust the interlaced flag and only deinterlace
2480 frames marked as interlaced
2484 deinterlace all frames
2486 only deinterlace frames marked as interlaced
2493 @c man end VIDEO FILTERS
2495 @chapter Video Sources
2496 @c man begin VIDEO SOURCES
2498 Below is a description of the currently available video sources.
2502 Buffer video frames, and make them available to the filter chain.
2504 This source is mainly intended for a programmatic use, in particular
2505 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2507 This filter accepts the following parameters:
2518 Name of the input video pixel format.
2521 The time base used for input timestamps.
2524 Sample (pixel) aspect ratio of the input video.
2530 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
2533 will instruct the source to accept video frames with size 320x240 and
2534 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2535 square pixels (1:1 sample aspect ratio).
2539 Provide an uniformly colored input.
2541 It accepts the following parameters:
2546 Specify the color of the source. It can be the name of a color (case
2547 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2548 alpha specifier. The default value is "black".
2551 Specify the size of the sourced video, it may be a string of the form
2552 @var{width}x@var{height}, or the name of a size abbreviation. The
2553 default value is "320x240".
2556 Specify the frame rate of the sourced video, as the number of frames
2557 generated per second. It has to be a string in the format
2558 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2559 number or a valid video frame rate abbreviation. The default value is
2564 For example the following graph description will generate a red source
2565 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2566 frames per second, which will be overlayed over the source connected
2567 to the pad with identifier "in".
2570 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2575 Read a video stream from a movie container.
2577 Note that this source is a hack that bypasses the standard input path. It can be
2578 useful in applications that do not support arbitrary filter graphs, but its use
2579 is discouraged in those that do. Specifically in @command{avconv} this filter
2580 should never be used, the @option{-filter_complex} option fully replaces it.
2582 This filter accepts the following options:
2587 The name of the resource to read (not necessarily a file but also a device or a
2588 stream accessed through some protocol).
2590 @item format_name, f
2591 Specifies the format assumed for the movie to read, and can be either
2592 the name of a container or an input device. If not specified the
2593 format is guessed from @var{movie_name} or by probing.
2595 @item seek_point, sp
2596 Specifies the seek point in seconds, the frames will be output
2597 starting from this seek point, the parameter is evaluated with
2598 @code{av_strtod} so the numerical value may be suffixed by an IS
2599 postfix. Default value is "0".
2601 @item stream_index, si
2602 Specifies the index of the video stream to read. If the value is -1,
2603 the best suited video stream will be automatically selected. Default
2608 This filter allows to overlay a second video on top of main input of
2609 a filtergraph as shown in this graph:
2611 input -----------> deltapts0 --> overlay --> output
2614 movie --> scale--> deltapts1 -------+
2617 Some examples follow:
2619 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2620 # on top of the input labelled as "in".
2621 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2622 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2624 # read from a video4linux2 device, and overlay it on top of the input
2626 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2627 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2633 Null video source, never return images. It is mainly useful as a
2634 template and to be employed in analysis / debugging tools.
2636 It accepts as optional parameter a string of the form
2637 @var{width}:@var{height}:@var{timebase}.
2639 @var{width} and @var{height} specify the size of the configured
2640 source. The default values of @var{width} and @var{height} are
2641 respectively 352 and 288 (corresponding to the CIF size format).
2643 @var{timebase} specifies an arithmetic expression representing a
2644 timebase. The expression can contain the constants "PI", "E", "PHI",
2645 "AVTB" (the default timebase), and defaults to the value "AVTB".
2649 Provide a frei0r source.
2651 To enable compilation of this filter you need to install the frei0r
2652 header and configure Libav with --enable-frei0r.
2654 This source accepts the following options:
2659 The size of the video to generate, may be a string of the form
2660 @var{width}x@var{height} or a frame size abbreviation.
2663 Framerate of the generated video, may be a string of the form
2664 @var{num}/@var{den} or a frame rate abbreviation.
2667 The name to the frei0r source to load. For more information regarding frei0r and
2668 how to set the parameters read the section @ref{frei0r} in the description of
2672 A '|'-separated list of parameters to pass to the frei0r source.
2676 Some examples follow:
2678 # generate a frei0r partik0l source with size 200x200 and framerate 10
2679 # which is overlayed on the overlay filter main input
2680 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
2683 @section rgbtestsrc, testsrc
2685 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2686 detecting RGB vs BGR issues. You should see a red, green and blue
2687 stripe from top to bottom.
2689 The @code{testsrc} source generates a test video pattern, showing a
2690 color pattern, a scrolling gradient and a timestamp. This is mainly
2691 intended for testing purposes.
2693 The sources accept the following options:
2698 Specify the size of the sourced video, it may be a string of the form
2699 @var{width}x@var{height}, or the name of a size abbreviation. The
2700 default value is "320x240".
2703 Specify the frame rate of the sourced video, as the number of frames
2704 generated per second. It has to be a string in the format
2705 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2706 number or a valid video frame rate abbreviation. The default value is
2710 Set the sample aspect ratio of the sourced video.
2713 Set the video duration of the sourced video. The accepted syntax is:
2715 [-]HH[:MM[:SS[.m...]]]
2718 See also the function @code{av_parse_time()}.
2720 If not specified, or the expressed duration is negative, the video is
2721 supposed to be generated forever.
2724 For example the following:
2726 testsrc=duration=5.3:size=qcif:rate=10
2729 will generate a video with a duration of 5.3 seconds, with size
2730 176x144 and a framerate of 10 frames per second.
2732 @c man end VIDEO SOURCES
2734 @chapter Video Sinks
2735 @c man begin VIDEO SINKS
2737 Below is a description of the currently available video sinks.
2741 Buffer video frames, and make them available to the end of the filter
2744 This sink is intended for a programmatic use through the interface defined in
2745 @file{libavfilter/buffersink.h}.
2749 Null video sink, do absolutely nothing with the input video. It is
2750 mainly useful as a template and to be employed in analysis / debugging
2753 @c man end VIDEO SINKS