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/avfiltergraph.h}.
26 A filterchain consists of a sequence of connected filters, each one
27 connected to the previous one in the sequence. A filterchain is
28 represented by a list of ","-separated filter descriptions.
30 A filtergraph consists of a sequence of filterchains. A sequence of
31 filterchains is represented by a list of ";"-separated filterchain
34 A filter is represented by a string of the form:
35 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
37 @var{filter_name} is the name of the filter class of which the
38 described filter is an instance of, and has to be the name of one of
39 the filter classes registered in the program.
40 The name of the filter class is optionally followed by a string
43 @var{arguments} is a string which contains the parameters used to
44 initialize the filter instance, and are described in the filter
47 The list of arguments can be quoted using the character "'" as initial
48 and ending mark, and the character '\' for escaping the characters
49 within the quoted text; otherwise the argument string is considered
50 terminated when the next special character (belonging to the set
51 "[]=;,") is encountered.
53 The name and arguments of the filter are optionally preceded and
54 followed by a list of link labels.
55 A link label allows to name a link and associate it to a filter output
56 or input pad. The preceding labels @var{in_link_1}
57 ... @var{in_link_N}, are associated to the filter input pads,
58 the following labels @var{out_link_1} ... @var{out_link_M}, are
59 associated to the output pads.
61 When two link labels with the same name are found in the
62 filtergraph, a link between the corresponding input and output pad is
65 If an output pad is not labelled, it is linked by default to the first
66 unlabelled input pad of the next filter in the filterchain.
67 For example in the filterchain:
69 nullsrc, split[L1], [L2]overlay, nullsink
71 the split filter instance has two output pads, and the overlay filter
72 instance two input pads. The first output pad of split is labelled
73 "L1", the first input pad of overlay is labelled "L2", and the second
74 output pad of split is linked to the second input pad of overlay,
75 which are both unlabelled.
77 In a complete filterchain all the unlabelled filter input and output
78 pads must be connected. A filtergraph is considered valid if all the
79 filter input and output pads of all the filterchains are connected.
81 Libavfilter will automatically insert scale filters where format
82 conversion is required. It is possible to specify swscale flags
83 for those automatically inserted scalers by prepending
84 @code{sws_flags=@var{flags};}
85 to the filtergraph description.
87 Follows a BNF description for the filtergraph syntax:
89 @var{NAME} ::= sequence of alphanumeric characters and '_'
90 @var{LINKLABEL} ::= "[" @var{NAME} "]"
91 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
92 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
93 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
94 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
95 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
98 @c man end FILTERGRAPH DESCRIPTION
100 @chapter Audio Filters
101 @c man begin AUDIO FILTERS
103 When you configure your Libav build, you can disable any of the
104 existing filters using --disable-filters.
105 The configure output will show the audio filters included in your
108 Below is a description of the currently available audio filters.
112 Convert the input audio to one of the specified formats. The framework will
113 negotiate the most appropriate format to minimize conversions.
115 The filter accepts the following named parameters:
119 A comma-separated list of requested sample formats.
122 A comma-separated list of requested sample rates.
124 @item channel_layouts
125 A comma-separated list of requested channel layouts.
129 If a parameter is omitted, all values are allowed.
131 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
133 aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo
138 Mixes multiple audio inputs into a single output.
142 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
144 will mix 3 input audio streams to a single output with the same duration as the
145 first input and a dropout transition time of 3 seconds.
147 The filter accepts the following named parameters:
151 Number of inputs. If unspecified, it defaults to 2.
154 How to determine the end-of-stream.
158 Duration of longest input. (default)
161 Duration of shortest input.
164 Duration of first input.
168 @item dropout_transition
169 Transition time, in seconds, for volume renormalization when an input
170 stream ends. The default value is 2 seconds.
176 Pass the audio source unchanged to the output.
180 Split input audio into several identical outputs.
182 The filter accepts a single parameter which specifies the number of outputs. If
183 unspecified, it defaults to 2.
187 avconv -i INPUT -filter_complex asplit=5 OUTPUT
189 will create 5 copies of the input audio.
192 Synchronize audio data with timestamps by squeezing/stretching it and/or
193 dropping samples/adding silence when needed.
195 The filter accepts the following named parameters:
199 Enable stretching/squeezing the data to make it match the timestamps.
202 Minimum difference between timestamps and audio data (in seconds) to trigger
203 adding/dropping samples.
206 Maximum compensation in samples per second.
210 @section channelsplit
211 Split each channel in input audio stream into a separate output stream.
213 This filter accepts the following named parameters:
216 Channel layout of the input stream. Default is "stereo".
219 For example, assuming a stereo input MP3 file
221 avconv -i in.mp3 -filter_complex channelsplit out.mkv
223 will create an output Matroska file with two audio streams, one containing only
224 the left channel and the other the right channel.
226 To split a 5.1 WAV file into per-channel files
228 avconv -i in.wav -filter_complex
229 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
230 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
231 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
236 Remap input channels to new locations.
238 This filter accepts the following named parameters:
241 Channel layout of the output stream.
244 Map channels from input to output. The argument is a comma-separated list of
245 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
246 @var{in_channel} form. @var{in_channel} can be either the name of the input
247 channel (e.g. FL for front left) or its index in the input channel layout.
248 @var{out_channel} is the name of the output channel or its index in the output
249 channel layout. If @var{out_channel} is not given then it is implicitly an
250 index, starting with zero and increasing by one for each mapping.
253 If no mapping is present, the filter will implicitly map input channels to
254 output channels preserving index.
256 For example, assuming a 5.1+downmix input MOV file
258 avconv -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
260 will create an output WAV file tagged as stereo from the downmix channels of
263 To fix a 5.1 WAV improperly encoded in AAC's native channel order
265 avconv -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
269 Join multiple input streams into one multi-channel stream.
271 The filter accepts the following named parameters:
275 Number of input streams. Defaults to 2.
278 Desired output channel layout. Defaults to stereo.
281 Map channels from inputs to output. The argument is a comma-separated list of
282 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
283 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
284 can be either the name of the input channel (e.g. FR for front left) or its
285 index in the specified input stream. @var{out_channel} is the name of the output
289 The filter will attempt to guess the mappings when those are not specified
290 explicitly. It does so by first trying to find an unused matching input channel
291 and if that fails it picks the first unused input channel.
293 E.g. to join 3 inputs (with properly set channel layouts)
295 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
298 To build a 5.1 output from 6 single-channel streams:
300 avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
301 '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'
306 Convert the audio sample format, sample rate and channel layout. This filter is
307 not meant to be used directly, it is inserted automatically by libavfilter
308 whenever conversion is needed. Use the @var{aformat} filter to force a specific
311 @c man end AUDIO FILTERS
313 @chapter Audio Sources
314 @c man begin AUDIO SOURCES
316 Below is a description of the currently available audio sources.
320 Null audio source, never return audio frames. It is mainly useful as a
321 template and to be employed in analysis / debugging tools.
323 It accepts as optional parameter a string of the form
324 @var{sample_rate}:@var{channel_layout}.
326 @var{sample_rate} specify the sample rate, and defaults to 44100.
328 @var{channel_layout} specify the channel layout, and can be either an
329 integer or a string representing a channel layout. The default value
330 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
332 Check the channel_layout_map definition in
333 @file{libavcodec/audioconvert.c} for the mapping between strings and
334 channel layout values.
336 Follow some examples:
338 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
346 Buffer audio frames, and make them available to the filter chain.
348 This source is not intended to be part of user-supplied graph descriptions but
349 for insertion by calling programs through the interface defined in
350 @file{libavfilter/buffersrc.h}.
352 It accepts the following named parameters:
356 Timebase which will be used for timestamps of submitted frames. It must be
357 either a floating-point number or in @var{numerator}/@var{denominator} form.
363 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
366 Channel layout of the audio data, in the form that can be accepted by
367 @code{av_get_channel_layout()}.
370 All the parameters need to be explicitly defined.
372 @c man end AUDIO SOURCES
375 @c man begin AUDIO SINKS
377 Below is a description of the currently available audio sinks.
381 Null audio sink, do absolutely nothing with the input audio. It is
382 mainly useful as a template and to be employed in analysis / debugging
386 This sink is intended for programmatic use. Frames that arrive on this sink can
387 be retrieved by the calling program using the interface defined in
388 @file{libavfilter/buffersink.h}.
390 This filter accepts no parameters.
392 @c man end AUDIO SINKS
394 @chapter Video Filters
395 @c man begin VIDEO FILTERS
397 When you configure your Libav build, you can disable any of the
398 existing filters using --disable-filters.
399 The configure output will show the video filters included in your
402 Below is a description of the currently available video filters.
406 Detect frames that are (almost) completely black. Can be useful to
407 detect chapter transitions or commercials. Output lines consist of
408 the frame number of the detected frame, the percentage of blackness,
409 the position in the file if known or -1 and the timestamp in seconds.
411 In order to display the output lines, you need to set the loglevel at
412 least to the AV_LOG_INFO value.
414 The filter accepts the syntax:
416 blackframe[=@var{amount}:[@var{threshold}]]
419 @var{amount} is the percentage of the pixels that have to be below the
420 threshold, and defaults to 98.
422 @var{threshold} is the threshold below which a pixel value is
423 considered black, and defaults to 32.
427 Apply boxblur algorithm to the input video.
429 This filter accepts the parameters:
430 @var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
432 Chroma and alpha parameters are optional, if not specified they default
433 to the corresponding values set for @var{luma_radius} and
436 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
437 the radius in pixels of the box used for blurring the corresponding
438 input plane. They are expressions, and can contain the following
442 the input width and height in pixels
445 the input chroma image width and height in pixels
448 horizontal and vertical chroma subsample values. For example for the
449 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
452 The radius must be a non-negative number, and must not be greater than
453 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
454 and of @code{min(cw,ch)/2} for the chroma planes.
456 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
457 how many times the boxblur filter is applied to the corresponding
460 Some examples follow:
465 Apply a boxblur filter with luma, chroma, and alpha radius
472 Set luma radius to 2, alpha and chroma radius to 0
478 Set luma and chroma radius to a fraction of the video dimension
480 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
487 Copy the input source unchanged to the output. Mainly useful for
492 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
494 The parameters are expressions containing the following constants:
498 the corresponding mathematical approximated values for e
499 (euler number), pi (greek PI), PHI (golden ratio)
502 the computed values for @var{x} and @var{y}. They are evaluated for
506 the input width and height
509 same as @var{in_w} and @var{in_h}
512 the output (cropped) width and height
515 same as @var{out_w} and @var{out_h}
518 the number of input frame, starting from 0
521 the position in the file of the input frame, NAN if unknown
524 timestamp expressed in seconds, NAN if the input timestamp is unknown
528 The @var{out_w} and @var{out_h} parameters specify the expressions for
529 the width and height of the output (cropped) video. They are
530 evaluated just at the configuration of the filter.
532 The default value of @var{out_w} is "in_w", and the default value of
533 @var{out_h} is "in_h".
535 The expression for @var{out_w} may depend on the value of @var{out_h},
536 and the expression for @var{out_h} may depend on @var{out_w}, but they
537 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
538 evaluated after @var{out_w} and @var{out_h}.
540 The @var{x} and @var{y} parameters specify the expressions for the
541 position of the top-left corner of the output (non-cropped) area. They
542 are evaluated for each frame. If the evaluated value is not valid, it
543 is approximated to the nearest valid value.
545 The default value of @var{x} is "(in_w-out_w)/2", and the default
546 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
547 the center of the input image.
549 The expression for @var{x} may depend on @var{y}, and the expression
550 for @var{y} may depend on @var{x}.
552 Follow some examples:
554 # crop the central input area with size 100x100
557 # crop the central input area with size 2/3 of the input video
558 "crop=2/3*in_w:2/3*in_h"
560 # crop the input video central square
563 # delimit the rectangle with the top-left corner placed at position
564 # 100:100 and the right-bottom corner corresponding to the right-bottom
565 # corner of the input image.
566 crop=in_w-100:in_h-100:100:100
568 # crop 10 pixels from the left and right borders, and 20 pixels from
569 # the top and bottom borders
570 "crop=in_w-2*10:in_h-2*20"
572 # keep only the bottom right quarter of the input image
573 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
575 # crop height for getting Greek harmony
576 "crop=in_w:1/PHI*in_w"
579 "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)"
581 # erratic camera effect depending on timestamp
582 "crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
584 # set x depending on the value of y
585 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
590 Auto-detect crop size.
592 Calculate necessary cropping parameters and prints the recommended
593 parameters through the logging system. The detected dimensions
594 correspond to the non-black area of the input video.
596 It accepts the syntax:
598 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
604 Threshold, which can be optionally specified from nothing (0) to
605 everything (255), defaults to 24.
608 Value which the width/height should be divisible by, defaults to
609 16. The offset is automatically adjusted to center the video. Use 2 to
610 get only even dimensions (needed for 4:2:2 video). 16 is best when
611 encoding to most video codecs.
614 Counter that determines after how many frames cropdetect will reset
615 the previously detected largest video area and start over to detect
616 the current optimal crop area. Defaults to 0.
618 This can be useful when channel logos distort the video area. 0
619 indicates never reset and return the largest area encountered during
625 Suppress a TV station logo by a simple interpolation of the surrounding
626 pixels. Just set a rectangle covering the logo and watch it disappear
627 (and sometimes something even uglier appear - your mileage may vary).
629 The filter accepts parameters as a string of the form
630 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
631 @var{key}=@var{value} pairs, separated by ":".
633 The description of the accepted parameters follows.
638 Specify the top left corner coordinates of the logo. They must be
642 Specify the width and height of the logo to clear. They must be
646 Specify the thickness of the fuzzy edge of the rectangle (added to
647 @var{w} and @var{h}). The default value is 4.
650 When set to 1, a green rectangle is drawn on the screen to simplify
651 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
652 @var{band} is set to 4. The default value is 0.
656 Some examples follow.
661 Set a rectangle covering the area with top left corner coordinates 0,0
662 and size 100x77, setting a band of size 10:
668 As the previous example, but use named options:
670 delogo=x=0:y=0:w=100:h=77:band=10
677 Draw a colored box on the input image.
679 It accepts the syntax:
681 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
687 Specify the top left corner coordinates of the box. Default to 0.
690 Specify the width and height of the box, if 0 they are interpreted as
691 the input width and height. Default to 0.
694 Specify the color of the box to write, it can be the name of a color
695 (case insensitive match) or a 0xRRGGBB[AA] sequence.
698 Follow some examples:
700 # draw a black box around the edge of the input image
703 # draw a box with color red and an opacity of 50%
704 drawbox=10:20:200:60:red@@0.5"
709 Draw text string or text from specified file on top of video using the
712 To enable compilation of this filter you need to configure Libav with
713 @code{--enable-libfreetype}.
715 The filter also recognizes strftime() sequences in the provided text
716 and expands them accordingly. Check the documentation of strftime().
718 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
721 The description of the accepted parameters follows.
726 The font file to be used for drawing text. Path must be included.
727 This parameter is mandatory.
730 The text string to be drawn. The text must be a sequence of UTF-8
732 This parameter is mandatory if no file is specified with the parameter
736 A text file containing text to be drawn. The text must be a sequence
737 of UTF-8 encoded characters.
739 This parameter is mandatory if no text string is specified with the
740 parameter @var{text}.
742 If both text and textfile are specified, an error is thrown.
745 The offsets where text will be drawn within the video frame.
746 Relative to the top/left border of the output image.
747 They accept expressions similar to the @ref{overlay} filter:
751 the computed values for @var{x} and @var{y}. They are evaluated for
755 main input width and height
758 same as @var{main_w} and @var{main_h}
761 rendered text width and height
764 same as @var{text_w} and @var{text_h}
767 the number of frames processed, starting from 0
770 timestamp expressed in seconds, NAN if the input timestamp is unknown
774 The default value of @var{x} and @var{y} is 0.
777 The font size to be used for drawing text.
778 The default value of @var{fontsize} is 16.
781 The color to be used for drawing fonts.
782 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
783 (e.g. "0xff000033"), possibly followed by an alpha specifier.
784 The default value of @var{fontcolor} is "black".
787 The color to be used for drawing box around text.
788 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
789 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
790 The default value of @var{boxcolor} is "white".
793 Used to draw a box around text using background color.
794 Value should be either 1 (enable) or 0 (disable).
795 The default value of @var{box} is 0.
797 @item shadowx, shadowy
798 The x and y offsets for the text shadow position with respect to the
799 position of the text. They can be either positive or negative
800 values. Default value for both is "0".
803 The color to be used for drawing a shadow behind the drawn text. It
804 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
805 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
806 The default value of @var{shadowcolor} is "black".
809 Flags to be used for loading the fonts.
811 The flags map the corresponding flags supported by libfreetype, and are
812 a combination of the following values:
819 @item vertical_layout
823 @item ignore_global_advance_width
825 @item ignore_transform
832 Default value is "render".
834 For more information consult the documentation for the FT_LOAD_*
838 The size in number of spaces to use for rendering the tab.
842 If true, check and fix text coords to avoid clipping.
845 For example the command:
847 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
850 will draw "Test Text" with font FreeSerif, using the default values
851 for the optional parameters.
855 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
856 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
859 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
860 and y=50 (counting from the top-left corner of the screen), text is
861 yellow with a red box around it. Both the text and the box have an
864 Note that the double quotes are not necessary if spaces are not used
865 within the parameter list.
867 For more information about libfreetype, check:
868 @url{http://www.freetype.org/}.
872 Apply fade-in/out effect to input video.
874 It accepts the parameters:
875 @var{type}:@var{start_frame}:@var{nb_frames}
877 @var{type} specifies if the effect type, can be either "in" for
878 fade-in, or "out" for a fade-out effect.
880 @var{start_frame} specifies the number of the start frame for starting
881 to apply the fade effect.
883 @var{nb_frames} specifies the number of frames for which the fade
884 effect has to last. At the end of the fade-in effect the output video
885 will have the same intensity as the input video, at the end of the
886 fade-out transition the output video will be completely black.
888 A few usage examples follow, usable too as test scenarios.
890 # fade in first 30 frames of video
893 # fade out last 45 frames of a 200-frame video
896 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
897 fade=in:0:25, fade=out:975:25
899 # make first 5 frames black, then fade in from frame 5-24
905 Transform the field order of the input video.
907 It accepts one parameter which specifies the required field order that
908 the input interlaced video will be transformed to. The parameter can
909 assume one of the following values:
913 output bottom field first
915 output top field first
918 Default value is "tff".
920 Transformation is achieved by shifting the picture content up or down
921 by one line, and filling the remaining line with appropriate picture content.
922 This method is consistent with most broadcast field order converters.
924 If the input video is not flagged as being interlaced, or it is already
925 flagged as being of the required output field order then this filter does
926 not alter the incoming video.
928 This filter is very useful when converting to or from PAL DV material,
929 which is bottom field first.
933 ./avconv -i in.vob -vf "fieldorder=bff" out.dv
938 Buffer input images and send them when they are requested.
940 This filter is mainly useful when auto-inserted by the libavfilter
943 The filter does not take parameters.
947 Convert the input video to one of the specified pixel formats.
948 Libavfilter will try to pick one that is supported for the input to
951 The filter accepts a list of pixel format names, separated by ":",
952 for example "yuv420p:monow:rgb24".
954 Some examples follow:
956 # convert the input video to the format "yuv420p"
959 # convert the input video to any of the formats in the list
960 format=yuv420p:yuv444p:yuv410p
965 Convert the video to specified constant framerate by duplicating or dropping
968 This filter accepts the following named parameters:
972 Desired output framerate.
979 Apply a frei0r effect to the input video.
981 To enable compilation of this filter you need to install the frei0r
982 header and configure Libav with --enable-frei0r.
984 The filter supports the syntax:
986 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
989 @var{filter_name} is the name to the frei0r effect to load. If the
990 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
991 is searched in each one of the directories specified by the colon
992 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
993 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
994 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
996 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
997 for the frei0r effect.
999 A frei0r effect parameter can be a boolean (whose values are specified
1000 with "y" and "n"), a double, a color (specified by the syntax
1001 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1002 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1003 description), a position (specified by the syntax @var{X}/@var{Y},
1004 @var{X} and @var{Y} being float numbers) and a string.
1006 The number and kind of parameters depend on the loaded effect. If an
1007 effect parameter is not specified the default value is set.
1009 Some examples follow:
1011 # apply the distort0r effect, set the first two double parameters
1012 frei0r=distort0r:0.5:0.01
1014 # apply the colordistance effect, takes a color as first parameter
1015 frei0r=colordistance:0.2/0.3/0.4
1016 frei0r=colordistance:violet
1017 frei0r=colordistance:0x112233
1019 # apply the perspective effect, specify the top left and top right
1021 frei0r=perspective:0.2/0.2:0.8/0.2
1024 For more information see:
1025 @url{http://piksel.org/frei0r}
1029 Fix the banding artifacts that are sometimes introduced into nearly flat
1030 regions by truncation to 8bit colordepth.
1031 Interpolate the gradients that should go where the bands are, and
1034 This filter is designed for playback only. Do not use it prior to
1035 lossy compression, because compression tends to lose the dither and
1036 bring back the bands.
1038 The filter takes two optional parameters, separated by ':':
1039 @var{strength}:@var{radius}
1041 @var{strength} is the maximum amount by which the filter will change
1042 any one pixel. Also the threshold for detecting nearly flat
1043 regions. Acceptable values range from .51 to 255, default value is
1044 1.2, out-of-range values will be clipped to the valid range.
1046 @var{radius} is the neighborhood to fit the gradient to. A larger
1047 radius makes for smoother gradients, but also prevents the filter from
1048 modifying the pixels near detailed regions. Acceptable values are
1049 8-32, default value is 16, out-of-range values will be clipped to the
1053 # default parameters
1062 Flip the input video horizontally.
1064 For example to horizontally flip the input video with @command{avconv}:
1066 avconv -i in.avi -vf "hflip" out.avi
1071 High precision/quality 3d denoise filter. This filter aims to reduce
1072 image noise producing smooth images and making still images really
1073 still. It should enhance compressibility.
1075 It accepts the following optional parameters:
1076 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1080 a non-negative float number which specifies spatial luma strength,
1083 @item chroma_spatial
1084 a non-negative float number which specifies spatial chroma strength,
1085 defaults to 3.0*@var{luma_spatial}/4.0
1088 a float number which specifies luma temporal strength, defaults to
1089 6.0*@var{luma_spatial}/4.0
1092 a float number which specifies chroma temporal strength, defaults to
1093 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1096 @section lut, lutrgb, lutyuv
1098 Compute a look-up table for binding each pixel component input value
1099 to an output value, and apply it to input video.
1101 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1102 to an RGB input video.
1104 These filters accept in input a ":"-separated list of options, which
1105 specify the expressions used for computing the lookup table for the
1106 corresponding pixel component values.
1108 The @var{lut} filter requires either YUV or RGB pixel formats in
1109 input, and accepts the options:
1111 @var{c0} (first pixel component)
1112 @var{c1} (second pixel component)
1113 @var{c2} (third pixel component)
1114 @var{c3} (fourth pixel component, corresponds to the alpha component)
1117 The exact component associated to each option depends on the format in
1120 The @var{lutrgb} filter requires RGB pixel formats in input, and
1121 accepts the options:
1123 @var{r} (red component)
1124 @var{g} (green component)
1125 @var{b} (blue component)
1126 @var{a} (alpha component)
1129 The @var{lutyuv} filter requires YUV pixel formats in input, and
1130 accepts the options:
1132 @var{y} (Y/luminance component)
1133 @var{u} (U/Cb component)
1134 @var{v} (V/Cr component)
1135 @var{a} (alpha component)
1138 The expressions can contain the following constants and functions:
1142 the corresponding mathematical approximated values for e
1143 (euler number), pi (greek PI), PHI (golden ratio)
1146 the input width and height
1149 input value for the pixel component
1152 the input value clipped in the @var{minval}-@var{maxval} range
1155 maximum value for the pixel component
1158 minimum value for the pixel component
1161 the negated value for the pixel component value clipped in the
1162 @var{minval}-@var{maxval} range , it corresponds to the expression
1163 "maxval-clipval+minval"
1166 the computed value in @var{val} clipped in the
1167 @var{minval}-@var{maxval} range
1169 @item gammaval(gamma)
1170 the computed gamma correction value of the pixel component value
1171 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1173 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1177 All expressions default to "val".
1179 Some examples follow:
1181 # negate input video
1182 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1183 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1185 # the above is the same as
1186 lutrgb="r=negval:g=negval:b=negval"
1187 lutyuv="y=negval:u=negval:v=negval"
1192 # remove chroma components, turns the video into a graytone image
1193 lutyuv="u=128:v=128"
1195 # apply a luma burning effect
1198 # remove green and blue components
1201 # set a constant alpha channel value on input
1202 format=rgba,lutrgb=a="maxval-minval/2"
1204 # correct luminance gamma by a 0.5 factor
1205 lutyuv=y=gammaval(0.5)
1212 This filter accepts an integer in input, if non-zero it negates the
1213 alpha component (if available). The default value in input is 0.
1215 Force libavfilter not to use any of the specified pixel formats for the
1216 input to the next filter.
1218 The filter accepts a list of pixel format names, separated by ":",
1219 for example "yuv420p:monow:rgb24".
1221 Some examples follow:
1223 # force libavfilter to use a format different from "yuv420p" for the
1224 # input to the vflip filter
1225 noformat=yuv420p,vflip
1227 # convert the input video to any of the formats not contained in the list
1228 noformat=yuv420p:yuv444p:yuv410p
1233 Pass the video source unchanged to the output.
1237 Apply video transform using libopencv.
1239 To enable this filter install libopencv library and headers and
1240 configure Libav with --enable-libopencv.
1242 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1244 @var{filter_name} is the name of the libopencv filter to apply.
1246 @var{filter_params} specifies the parameters to pass to the libopencv
1247 filter. If not specified the default values are assumed.
1249 Refer to the official libopencv documentation for more precise
1251 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1253 Follows the list of supported libopencv filters.
1258 Dilate an image by using a specific structuring element.
1259 This filter corresponds to the libopencv function @code{cvDilate}.
1261 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1263 @var{struct_el} represents a structuring element, and has the syntax:
1264 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1266 @var{cols} and @var{rows} represent the number of columns and rows of
1267 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1268 point, and @var{shape} the shape for the structuring element, and
1269 can be one of the values "rect", "cross", "ellipse", "custom".
1271 If the value for @var{shape} is "custom", it must be followed by a
1272 string of the form "=@var{filename}". The file with name
1273 @var{filename} is assumed to represent a binary image, with each
1274 printable character corresponding to a bright pixel. When a custom
1275 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1276 or columns and rows of the read file are assumed instead.
1278 The default value for @var{struct_el} is "3x3+0x0/rect".
1280 @var{nb_iterations} specifies the number of times the transform is
1281 applied to the image, and defaults to 1.
1283 Follow some example:
1285 # use the default values
1288 # dilate using a structuring element with a 5x5 cross, iterate two times
1289 ocv=dilate=5x5+2x2/cross:2
1291 # read the shape from the file diamond.shape, iterate two times
1292 # the file diamond.shape may contain a pattern of characters like this:
1298 # the specified cols and rows are ignored (but not the anchor point coordinates)
1299 ocv=0x0+2x2/custom=diamond.shape:2
1304 Erode an image by using a specific structuring element.
1305 This filter corresponds to the libopencv function @code{cvErode}.
1307 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1308 with the same syntax and semantics as the @ref{dilate} filter.
1312 Smooth the input video.
1314 The filter takes the following parameters:
1315 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1317 @var{type} is the type of smooth filter to apply, and can be one of
1318 the following values: "blur", "blur_no_scale", "median", "gaussian",
1319 "bilateral". The default value is "gaussian".
1321 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1322 parameters whose meanings depend on smooth type. @var{param1} and
1323 @var{param2} accept integer positive values or 0, @var{param3} and
1324 @var{param4} accept float values.
1326 The default value for @var{param1} is 3, the default value for the
1327 other parameters is 0.
1329 These parameters correspond to the parameters assigned to the
1330 libopencv function @code{cvSmooth}.
1335 Overlay one video on top of another.
1337 It takes two inputs and one output, the first input is the "main"
1338 video on which the second input is overlayed.
1340 It accepts the parameters: @var{x}:@var{y}.
1342 @var{x} is the x coordinate of the overlayed video on the main video,
1343 @var{y} is the y coordinate. The parameters are expressions containing
1344 the following parameters:
1347 @item main_w, main_h
1348 main input width and height
1351 same as @var{main_w} and @var{main_h}
1353 @item overlay_w, overlay_h
1354 overlay input width and height
1357 same as @var{overlay_w} and @var{overlay_h}
1360 Be aware that frames are taken from each input video in timestamp
1361 order, hence, if their initial timestamps differ, it is a a good idea
1362 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1363 have them begin in the same zero timestamp, as it does the example for
1364 the @var{movie} filter.
1366 Follow some examples:
1368 # draw the overlay at 10 pixels from the bottom right
1369 # corner of the main video.
1370 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1372 # insert a transparent PNG logo in the bottom left corner of the input
1373 avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
1375 # insert 2 different transparent PNG logos (second logo on bottom
1377 avconv -i input -i logo1 -i logo2 -filter_complex
1378 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
1380 # add a transparent color layer on top of the main video,
1381 # WxH specifies the size of the main input to the overlay filter
1382 color=red@.3:WxH [over]; [in][over] overlay [out]
1385 You can chain together more overlays but the efficiency of such
1386 approach is yet to be tested.
1390 Add paddings to the input image, and places the original input at the
1391 given coordinates @var{x}, @var{y}.
1393 It accepts the following parameters:
1394 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1396 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1397 expressions containing the following constants:
1401 the corresponding mathematical approximated values for e
1402 (euler number), pi (greek PI), phi (golden ratio)
1405 the input video width and height
1408 same as @var{in_w} and @var{in_h}
1411 the output width and height, that is the size of the padded area as
1412 specified by the @var{width} and @var{height} expressions
1415 same as @var{out_w} and @var{out_h}
1418 x and y offsets as specified by the @var{x} and @var{y}
1419 expressions, or NAN if not yet specified
1422 input display aspect ratio, same as @var{iw} / @var{ih}
1425 horizontal and vertical chroma subsample values. For example for the
1426 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1429 Follows the description of the accepted parameters.
1434 Specify the size of the output image with the paddings added. If the
1435 value for @var{width} or @var{height} is 0, the corresponding input size
1436 is used for the output.
1438 The @var{width} expression can reference the value set by the
1439 @var{height} expression, and vice versa.
1441 The default value of @var{width} and @var{height} is 0.
1445 Specify the offsets where to place the input image in the padded area
1446 with respect to the top/left border of the output image.
1448 The @var{x} expression can reference the value set by the @var{y}
1449 expression, and vice versa.
1451 The default value of @var{x} and @var{y} is 0.
1455 Specify the color of the padded area, it can be the name of a color
1456 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1458 The default value of @var{color} is "black".
1462 Some examples follow:
1465 # Add paddings with color "violet" to the input video. Output video
1466 # size is 640x480, the top-left corner of the input video is placed at
1468 pad=640:480:0:40:violet
1470 # pad the input to get an output with dimensions increased bt 3/2,
1471 # and put the input video at the center of the padded area
1472 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1474 # pad the input to get a squared output with size equal to the maximum
1475 # value between the input width and height, and put the input video at
1476 # the center of the padded area
1477 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1479 # pad the input to get a final w/h ratio of 16:9
1480 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1482 # double output size and put the input video in the bottom-right
1483 # corner of the output padded area
1484 pad="2*iw:2*ih:ow-iw:oh-ih"
1487 @section pixdesctest
1489 Pixel format descriptor test filter, mainly useful for internal
1490 testing. The output video should be equal to the input video.
1494 format=monow, pixdesctest
1497 can be used to test the monowhite pixel format descriptor definition.
1501 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1503 The parameters @var{width} and @var{height} are expressions containing
1504 the following constants:
1508 the corresponding mathematical approximated values for e
1509 (euler number), pi (greek PI), phi (golden ratio)
1512 the input width and height
1515 same as @var{in_w} and @var{in_h}
1518 the output (cropped) width and height
1521 same as @var{out_w} and @var{out_h}
1524 input display aspect ratio, same as @var{iw} / @var{ih}
1527 input sample aspect ratio
1530 horizontal and vertical chroma subsample values. For example for the
1531 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1534 If the input image format is different from the format requested by
1535 the next filter, the scale filter will convert the input to the
1538 If the value for @var{width} or @var{height} is 0, the respective input
1539 size is used for the output.
1541 If the value for @var{width} or @var{height} is -1, the scale filter will
1542 use, for the respective output size, a value that maintains the aspect
1543 ratio of the input image.
1545 The default value of @var{width} and @var{height} is 0.
1547 Some examples follow:
1549 # scale the input video to a size of 200x100.
1552 # scale the input to 2x
1554 # the above is the same as
1557 # scale the input to half size
1560 # increase the width, and set the height to the same size
1563 # seek for Greek harmony
1567 # increase the height, and set the width to 3/2 of the height
1570 # increase the size, but make the size a multiple of the chroma
1571 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1573 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1574 scale='min(500\, iw*3/2):-1'
1578 Select frames to pass in output.
1580 It accepts in input an expression, which is evaluated for each input
1581 frame. If the expression is evaluated to a non-zero value, the frame
1582 is selected and passed to the output, otherwise it is discarded.
1584 The expression can contain the following constants:
1597 the sequential number of the filtered frame, starting from 0
1600 the sequential number of the selected frame, starting from 0
1602 @item prev_selected_n
1603 the sequential number of the last selected frame, NAN if undefined
1606 timebase of the input timestamps
1609 the PTS (Presentation TimeStamp) of the filtered video frame,
1610 expressed in @var{TB} units, NAN if undefined
1613 the PTS (Presentation TimeStamp) of the filtered video frame,
1614 expressed in seconds, NAN if undefined
1617 the PTS of the previously filtered video frame, NAN if undefined
1619 @item prev_selected_pts
1620 the PTS of the last previously filtered video frame, NAN if undefined
1622 @item prev_selected_t
1623 the PTS of the last previously selected video frame, NAN if undefined
1626 the PTS of the first video frame in the video, NAN if undefined
1629 the time of the first video frame in the video, NAN if undefined
1632 the type of the filtered frame, can assume one of the following
1644 @item interlace_type
1645 the frame interlace type, can assume one of the following values:
1648 the frame is progressive (not interlaced)
1650 the frame is top-field-first
1652 the frame is bottom-field-first
1656 1 if the filtered frame is a key-frame, 0 otherwise
1659 the position in the file of the filtered frame, -1 if the information
1660 is not available (e.g. for synthetic video)
1663 The default value of the select expression is "1".
1665 Some examples follow:
1668 # select all frames in input
1671 # the above is the same as:
1677 # select only I-frames
1678 select='eq(pict_type\,I)'
1680 # select one frame every 100
1681 select='not(mod(n\,100))'
1683 # select only frames contained in the 10-20 time interval
1684 select='gte(t\,10)*lte(t\,20)'
1686 # select only I frames contained in the 10-20 time interval
1687 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1689 # select frames with a minimum distance of 10 seconds
1690 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1696 Set the Display Aspect Ratio for the filter output video.
1698 This is done by changing the specified Sample (aka Pixel) Aspect
1699 Ratio, according to the following equation:
1700 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1702 Keep in mind that this filter does not modify the pixel dimensions of
1703 the video frame. Also the display aspect ratio set by this filter may
1704 be changed by later filters in the filterchain, e.g. in case of
1705 scaling or if another "setdar" or a "setsar" filter is applied.
1707 The filter accepts a parameter string which represents the wanted
1708 display aspect ratio.
1709 The parameter can be a floating point number string, or an expression
1710 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1711 numerator and denominator of the aspect ratio.
1712 If the parameter is not specified, it is assumed the value "0:1".
1714 For example to change the display aspect ratio to 16:9, specify:
1717 # the above is equivalent to
1721 See also the @ref{setsar} filter documentation.
1725 Change the PTS (presentation timestamp) of the input video frames.
1727 Accept in input an expression evaluated through the eval API, which
1728 can contain the following constants:
1732 the presentation timestamp in input
1744 the count of the input frame, starting from 0.
1747 the PTS of the first video frame
1750 tell if the current frame is interlaced
1753 original position in the file of the frame, or undefined if undefined
1754 for the current frame
1764 Some examples follow:
1767 # start counting PTS from zero
1779 # fixed rate 25 fps with some jitter
1780 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1786 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1788 Note that as a consequence of the application of this filter, the
1789 output display aspect ratio will change according to the following
1791 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1793 Keep in mind that the sample aspect ratio set by this filter may be
1794 changed by later filters in the filterchain, e.g. if another "setsar"
1795 or a "setdar" filter is applied.
1797 The filter accepts a parameter string which represents the wanted
1798 sample aspect ratio.
1799 The parameter can be a floating point number string, or an expression
1800 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1801 numerator and denominator of the aspect ratio.
1802 If the parameter is not specified, it is assumed the value "0:1".
1804 For example to change the sample aspect ratio to 10:11, specify:
1811 Set the timebase to use for the output frames timestamps.
1812 It is mainly useful for testing timebase configuration.
1814 It accepts in input an arithmetic expression representing a rational.
1815 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1816 default timebase), and "intb" (the input timebase).
1818 The default value for the input is "intb".
1820 Follow some examples.
1823 # set the timebase to 1/25
1826 # set the timebase to 1/10
1829 #set the timebase to 1001/1000
1832 #set the timebase to 2*intb
1835 #set the default timebase value
1841 Show a line containing various information for each input video frame.
1842 The input video is not modified.
1844 The shown line contains a sequence of key/value pairs of the form
1845 @var{key}:@var{value}.
1847 A description of each shown parameter follows:
1851 sequential number of the input frame, starting from 0
1854 Presentation TimeStamp of the input frame, expressed as a number of
1855 time base units. The time base unit depends on the filter input pad.
1858 Presentation TimeStamp of the input frame, expressed as a number of
1862 position of the frame in the input stream, -1 if this information in
1863 unavailable and/or meaningless (for example in case of synthetic video)
1869 sample aspect ratio of the input frame, expressed in the form
1873 size of the input frame, expressed in the form
1874 @var{width}x@var{height}
1877 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1878 for bottom field first)
1881 1 if the frame is a key frame, 0 otherwise
1884 picture type of the input frame ("I" for an I-frame, "P" for a
1885 P-frame, "B" for a B-frame, "?" for unknown type).
1886 Check also the documentation of the @code{AVPictureType} enum and of
1887 the @code{av_get_picture_type_char} function defined in
1888 @file{libavutil/avutil.h}.
1891 Adler-32 checksum of all the planes of the input frame
1893 @item plane_checksum
1894 Adler-32 checksum of each plane of the input frame, expressed in the form
1895 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1900 Pass the images of input video on to next video filter as multiple
1904 ./avconv -i in.avi -vf "slicify=32" out.avi
1907 The filter accepts the slice height as parameter. If the parameter is
1908 not specified it will use the default value of 16.
1910 Adding this in the beginning of filter chains should make filtering
1911 faster due to better use of the memory cache.
1915 Split input video into several identical outputs.
1917 The filter accepts a single parameter which specifies the number of outputs. If
1918 unspecified, it defaults to 2.
1922 avconv -i INPUT -filter_complex split=5 OUTPUT
1924 will create 5 copies of the input video.
1928 Transpose rows with columns in the input video and optionally flip it.
1930 It accepts a parameter representing an integer, which can assume the
1935 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1943 Rotate by 90 degrees clockwise, that is:
1951 Rotate by 90 degrees counterclockwise, that is:
1959 Rotate by 90 degrees clockwise and vertically flip, that is:
1969 Sharpen or blur the input video.
1971 It accepts the following parameters:
1972 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1974 Negative values for the amount will blur the input video, while positive
1975 values will sharpen. All parameters are optional and default to the
1976 equivalent of the string '5:5:1.0:5:5:0.0'.
1981 Set the luma matrix horizontal size. It can be an integer between 3
1982 and 13, default value is 5.
1985 Set the luma matrix vertical size. It can be an integer between 3
1986 and 13, default value is 5.
1989 Set the luma effect strength. It can be a float number between -2.0
1990 and 5.0, default value is 1.0.
1992 @item chroma_msize_x
1993 Set the chroma matrix horizontal size. It can be an integer between 3
1994 and 13, default value is 5.
1996 @item chroma_msize_y
1997 Set the chroma matrix vertical size. It can be an integer between 3
1998 and 13, default value is 5.
2001 Set the chroma effect strength. It can be a float number between -2.0
2002 and 5.0, default value is 0.0.
2007 # Strong luma sharpen effect parameters
2010 # Strong blur of both luma and chroma parameters
2011 unsharp=7:7:-2:7:7:-2
2013 # Use the default values with @command{avconv}
2014 ./avconv -i in.avi -vf "unsharp" out.mp4
2019 Flip the input video vertically.
2022 ./avconv -i in.avi -vf "vflip" out.avi
2027 Deinterlace the input video ("yadif" means "yet another deinterlacing
2030 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2032 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2037 output 1 frame for each frame
2039 output 1 frame for each field
2041 like 0 but skips spatial interlacing check
2043 like 1 but skips spatial interlacing check
2048 @var{parity} specifies the picture field parity assumed for the input
2049 interlaced video, accepts one of the following values:
2053 assume top field first
2055 assume bottom field first
2057 enable automatic detection
2060 Default value is -1.
2061 If interlacing is unknown or decoder does not export this information,
2062 top field first will be assumed.
2064 @var{auto} specifies if deinterlacer should trust the interlaced flag
2065 and only deinterlace frames marked as interlaced
2069 deinterlace all frames
2071 only deinterlace frames marked as interlaced
2076 @c man end VIDEO FILTERS
2078 @chapter Video Sources
2079 @c man begin VIDEO SOURCES
2081 Below is a description of the currently available video sources.
2085 Buffer video frames, and make them available to the filter chain.
2087 This source is mainly intended for a programmatic use, in particular
2088 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2090 It accepts the following parameters:
2091 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
2093 All the parameters need to be explicitly defined.
2095 Follows the list of the accepted parameters.
2100 Specify the width and height of the buffered video frames.
2102 @item pix_fmt_string
2103 A string representing the pixel format of the buffered video frames.
2104 It may be a number corresponding to a pixel format, or a pixel format
2107 @item timebase_num, timebase_den
2108 Specify numerator and denomitor of the timebase assumed by the
2109 timestamps of the buffered frames.
2111 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2112 Specify numerator and denominator of the sample aspect ratio assumed
2113 by the video frames.
2118 buffer=320:240:yuv410p:1:24:1:1
2121 will instruct the source to accept video frames with size 320x240 and
2122 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2123 square pixels (1:1 sample aspect ratio).
2124 Since the pixel format with name "yuv410p" corresponds to the number 6
2125 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2126 this example corresponds to:
2128 buffer=320:240:6:1:24
2133 Provide an uniformly colored input.
2135 It accepts the following parameters:
2136 @var{color}:@var{frame_size}:@var{frame_rate}
2138 Follows the description of the accepted parameters.
2143 Specify the color of the source. It can be the name of a color (case
2144 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2145 alpha specifier. The default value is "black".
2148 Specify the size of the sourced video, it may be a string of the form
2149 @var{width}x@var{height}, or the name of a size abbreviation. The
2150 default value is "320x240".
2153 Specify the frame rate of the sourced video, as the number of frames
2154 generated per second. It has to be a string in the format
2155 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2156 number or a valid video frame rate abbreviation. The default value is
2161 For example the following graph description will generate a red source
2162 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2163 frames per second, which will be overlayed over the source connected
2164 to the pad with identifier "in".
2167 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2172 Read a video stream from a movie container.
2174 It accepts the syntax: @var{movie_name}[:@var{options}] where
2175 @var{movie_name} is the name of the resource to read (not necessarily
2176 a file but also a device or a stream accessed through some protocol),
2177 and @var{options} is an optional sequence of @var{key}=@var{value}
2178 pairs, separated by ":".
2180 The description of the accepted options follows.
2184 @item format_name, f
2185 Specifies the format assumed for the movie to read, and can be either
2186 the name of a container or an input device. If not specified the
2187 format is guessed from @var{movie_name} or by probing.
2189 @item seek_point, sp
2190 Specifies the seek point in seconds, the frames will be output
2191 starting from this seek point, the parameter is evaluated with
2192 @code{av_strtod} so the numerical value may be suffixed by an IS
2193 postfix. Default value is "0".
2195 @item stream_index, si
2196 Specifies the index of the video stream to read. If the value is -1,
2197 the best suited video stream will be automatically selected. Default
2202 This filter allows to overlay a second video on top of main input of
2203 a filtergraph as shown in this graph:
2205 input -----------> deltapts0 --> overlay --> output
2208 movie --> scale--> deltapts1 -------+
2211 Some examples follow:
2213 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2214 # on top of the input labelled as "in".
2215 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2216 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2218 # read from a video4linux2 device, and overlay it on top of the input
2220 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2221 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2227 Null video source, never return images. It is mainly useful as a
2228 template and to be employed in analysis / debugging tools.
2230 It accepts as optional parameter a string of the form
2231 @var{width}:@var{height}:@var{timebase}.
2233 @var{width} and @var{height} specify the size of the configured
2234 source. The default values of @var{width} and @var{height} are
2235 respectively 352 and 288 (corresponding to the CIF size format).
2237 @var{timebase} specifies an arithmetic expression representing a
2238 timebase. The expression can contain the constants "PI", "E", "PHI",
2239 "AVTB" (the default timebase), and defaults to the value "AVTB".
2243 Provide a frei0r source.
2245 To enable compilation of this filter you need to install the frei0r
2246 header and configure Libav with --enable-frei0r.
2248 The source supports the syntax:
2250 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2253 @var{size} is the size of the video to generate, may be a string of the
2254 form @var{width}x@var{height} or a frame size abbreviation.
2255 @var{rate} is the rate of the video to generate, may be a string of
2256 the form @var{num}/@var{den} or a frame rate abbreviation.
2257 @var{src_name} is the name to the frei0r source to load. For more
2258 information regarding frei0r and how to set the parameters read the
2259 section @ref{frei0r} in the description of the video filters.
2261 Some examples follow:
2263 # generate a frei0r partik0l source with size 200x200 and framerate 10
2264 # which is overlayed on the overlay filter main input
2265 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2268 @section rgbtestsrc, testsrc
2270 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2271 detecting RGB vs BGR issues. You should see a red, green and blue
2272 stripe from top to bottom.
2274 The @code{testsrc} source generates a test video pattern, showing a
2275 color pattern, a scrolling gradient and a timestamp. This is mainly
2276 intended for testing purposes.
2278 Both sources accept an optional sequence of @var{key}=@var{value} pairs,
2279 separated by ":". The description of the accepted options follows.
2284 Specify the size of the sourced video, it may be a string of the form
2285 @var{width}x@var{height}, or the name of a size abbreviation. The
2286 default value is "320x240".
2289 Specify the frame rate of the sourced video, as the number of frames
2290 generated per second. It has to be a string in the format
2291 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2292 number or a valid video frame rate abbreviation. The default value is
2296 Set the sample aspect ratio of the sourced video.
2299 Set the video duration of the sourced video. The accepted syntax is:
2301 [-]HH[:MM[:SS[.m...]]]
2304 See also the function @code{av_parse_time()}.
2306 If not specified, or the expressed duration is negative, the video is
2307 supposed to be generated forever.
2310 For example the following:
2312 testsrc=duration=5.3:size=qcif:rate=10
2315 will generate a video with a duration of 5.3 seconds, with size
2316 176x144 and a framerate of 10 frames per second.
2318 @c man end VIDEO SOURCES
2320 @chapter Video Sinks
2321 @c man begin VIDEO SINKS
2323 Below is a description of the currently available video sinks.
2327 Buffer video frames, and make them available to the end of the filter
2330 This sink is intended for a programmatic use through the interface defined in
2331 @file{libavfilter/buffersink.h}.
2335 Null video sink, do absolutely nothing with the input video. It is
2336 mainly useful as a template and to be employed in analysis / debugging
2339 @c man end VIDEO SINKS